PLASMA PROTEIN LOSS DURING SURGERY: BENEFICIAL EFFECTS OF ALBUMIN SUBSTITUTION

Plasma protein loss during abdominal surgery is a known phenomenon, but its possible pathophysiological relevance has remained unknown. The present study evaluates the effects of albumin substitution on systemic and local hemodynamics and cellular interactions in the mesenteric microcirculation. Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Plasma protein concentrations, systemic and local hemodynamics were recorded during the follow up period, with or without albumin substitution. Depending on the time course of plasma protein loss in control experiments, 80% of the calculated protein loss was infused dur…

A proton-translocating H+-ATPase is involved in C6 glial pH regulation.

AbstractGlial cells extrude acid equivalents to maintain pHi. Although four mechanisms have been described so far, pHi-control under physiological conditions is still not sufficiently explained. We therefore investigated whether a H+-translocating ATPase is involved in glial pHi homeostasis using an established glial cell line (C6 glioma). In the absence of bicarbonate, the inhibition of H+-ATPases by NEM led to a pHi decrease. The application of a more specific inhibitor (NBD-Cl) showed that the H+-ATPase involved is of the vacuolar type. Inhibition went along with delayed cell swelling. Together with the fact that glial acidification was far more pronounced in Na+-free media, this may ser…

Description of the response of a new multi-parametric brain sensor to physiological and pathophysiological challenges in the cortex of juvenile pigs

AIM Monitoring of intracranial pressure (ICP), local cerebral blood flow (CBF) and oxygen is part of modern intensive critical care medicine. Preclinical evaluation of newly developed catheters that should monitor several parameters simultaneously is reported poorly in the literature. The goal of our study was (1) to evaluate a new multi-parametric sensor in brain tissue and (2) to establish a testing protocol using pathophysiological challenges that target measured parameters of the sensor and autoregulatory boundaries and could be used as preclinical standard protocol in future studies. MATERIAL AND METHODS We describe data from 12 new multi-parametric brain sensors (MPBS) that were impla…

Initiation of high-frequency oscillatory ventilation and its effects upon cerebral circulation in pigs: an experimental study

BACKGROUND: Current practice at high-frequency oscillatory ventilation (HFOV) initiation is a stepwise increase of the constant applied airway pressure to achieve lung recruitment. We hypothesized that HFOV would lead to more adverse cerebral haemodynamics than does pressure controlled ventilation (PCV) in the presence of experimental intracranial hypertension (IH) and acute lung injury (ALI) in pigs with similar mean airway pressure settings. METHODS: In 12 anesthetized pigs (24-27 kg) with IH and ALI, mean airway pressure (P(mean)) was increased (to 20, 25, 30 cm H(2)O every 30 min), either with HFOV or with PCV. The order of the two ventilatory modes (cross-over) was randomized. Mean art…

Vitamin E supplements in standard rodent diets do not affect antioxidant intervention trials in apo-/-mice: failure of vitamin E to inhibit atherogenesis as assessed by histology in aortic arch and innominate/carotid arteries

A New Model of Skull Base Reconstruction following Expanded Endonasal or Transoral Approaches – Long-Term Results in Primates

<i>Objective:</i> The direct endonasal or transoral transclival approaches to the skull base permit effective minimally invasive surgery along the clivus region. Developing consistently effective techniques to prevent cerebrospinal fluid (CSF) leaks and their consequences (infections and healing processes with long and complicated recoveries) remains a major challenge. In this study, we tested over a long period a method of bone reconstruction newly developed by us, which makes use of a specially designed elastic silicone plug that can be employed for bone replacement after minimally invasive skull base surgery without risk of postoperative CSF leaks. After acute testing of plug…

Reperfusionsschock nach okklusion der A. mesenterica superior und akkumulation von leukozyten innerhalb der d�nndarmwand

Der Epithelschaden und die Leukozytenakkumulation in der Wand des Ileums nach Ischamie und Reperfusion wurden experimentell am Schwein untersucht. Die A. mesenterica superior wurde fur 1 h (Gruppe 2; n=9), 2 h (Gruppe 3; n=6) und 3 h (Gruppe 4; n=7) abgeklemmt und 2 h reperfundiert. Die histologische Beurteilung erfolgte an Hamatoxylin-Eosin- und NaphtolAS-D-Chlorazetatesterase-gefarbten Praparaten. Es entwickelte sich ein Reperfusionsschock in Abhangigkeit von der Ischamiedauer. Nach lstundiger Ischamie stabilisierte sich der Blutdruck mit erniedrigten Werten sowie einer Normalisierung des Serumlaktatspiegels und des intramuralen pHi des Dunndarms. Eine Verlangerung der Ischamie auf 2 h (G…

Surgical procedure affects physiological parameters in rat myocardial ischemia: need for mechanical ventilation.

Several surgical approaches are being used to induce myocardial ischemia in rats. The present study investigated two different operative procedures in spontaneously breathing and mechanically ventilated rats under sham conditions. A snare around the left coronary artery (LCA) was achieved without occlusion. Left lateral thoracotomy was performed in spontaneously breathing and mechanically ventilated rats (tidal volume 8 ml/kg) with a respiratory rate of 90 strokes/min at different levels of O2 supplementation (room air and 30, 40, and 90% O2). All animals were observed for 60 min after thoracotomy. Rats operated with exteriorization of the heart through left lateral thoracotomy while breat…

Effect of Torasemide — A New Cl--Transport Inhibitor on Glial Swelling by Lactacidosis and Glutamate

Cytotoxic brain edema, i.e. swelling of glial- and nerve cells is a common result of cerebral ischemia, brain trauma, metabolic disorders, and develops secondarily in vasogenic edema. During ischemia and severe head injury, brain tissue homeostasis is severely changed, and many parameters are simultaneously affected. To dissect and isolate the causal mechanisms leading to swelling of nerve- and glial cells, our laboratory has established an in vitro model [4, 5]. Thereby pathomechanisms can be studied in isolation without interference of epiphenomena taking place in damaged brain tissue under circumstances of cerebral ischemia or trauma. In previous studies the role of acidosis in cell swel…

Low-Frequency Therapeutic Ultrasound with Varied Duty Cycle: Effects on the Ischemic Brain and the Inner Ear

Sonothrombolysis is a promising modality for acute stroke treatment. In vitro data suggest a duty cycle dependence of sonothrombolytic efficacy of low-frequency applications. The aim of our study was to examine its impact on safety issues in a rat model of middle cerebral artery occlusion. Rats were exposed to transcranial 60-kHz ultrasound with varied duty cycles. To determine effects on the inner ear, the acoustic threshold was determined in additional healthy animals (acoustic evoked potentials). A short duty cycle (20%) resulted in significant adverse effects (ischemic volume, hemorrhage, functional outcome), which was not observed in longer duty cycle (80%). Continuous-wave insonation …

Effects of a small acute subdural hematoma following traumatic brain injury on neuromonitoring, brain swelling and histology in pigs.

An acute subdural hematoma (ASDH) induces pathomechanisms which worsen outcome after traumatic brain injury, even after a small hemorrhage. Synergistic effects of a small ASDH on brain damage are poorly understood, and were studied here using neuromonitoring for 10 h in an injury model of controlled cortical impact (CCI) and ASDH. Pigs (n = 32) were assigned to 4 groups: sham, CCI (2.5 m/s), ASDH (2 ml) and CCI + ASDH. Intracranial pressure was significantly increased above sham levels by all injuries with no difference between groups. CCI and ASDH reduced ptiO<sub>2</sub> by a maximum of 36 ± 9 and 26 ± 11%, respectively. The combination caused a 31 ± 11% drop. ASDH alone and i…

Aufnahme und Phototoxizität von Hämatoporphyrinderivat in normalen und malignen Zellen

Die Photodynamische Therapie (PDT) stellt neben der Chemo-, Radio- und chirurgischen Therapie ein neues alternatives Therapiekonzept in der Behandlung von malignen Tumoren dar. Das Prinzip beruht auf der systemischen Applikation (i.v. Injektion) einer photosensibilisierenden Substanz, z.B. Hamatoporphyrinderivat (HPD), und der nachfolgenden Bestrahlung mit Licht geeigneter Wellenlange, z.B. Laserlicht (630 nm). Fur die tumorselektive Wirkung dieser Therapie werden die selektive Aufnahme bzw. vermehrte Speicherung der photoaktiven Substanzen im Tumorgewebe [1] sowie auch eine im Vergleich zum Normalgewebe erhohte Sensibuitat von Tumorgewebe gegenuber der PDT postuliert. Ungeklart ist, ob die…

Neuronal immunoreactivity for mannose-binding lectin after venous occlusion-induced focal cerebral ischemia in rats

Abstract A recent research reveals that complement activation exacerbates cerebral infarction. However, involvement of the lectin pathway, (the third complement activation pathway) in cerebral ischemia is not well studied. In this study, we investigated the appearance of mannose-binding lectin (MBL) in ischemic brain tissue. Male Wistar rats ( n  = 25) were divided into three groups: untreated control, sham, and vein occlusion (VO). Rats in the VO group had two adjacent photochemically occluded cortical veins. Regional cerebral blood flow (rCBF) was measured in the sham and VO groups. Rats were perfusion-fixed at 72 h in the sham group and at 3, 24, and 72 h after inducing ischemia in the V…

Cytotoxic Glial Swelling by Arachidonic Acid

Arachidonic acid (AA, 20:4) is a major constituent of membrane phospholipids in brain tissue. Normally, the free fatty acid is present only in a small amount, but it accumulates under adverse conditions, such as ischemia or brain injury [1,9]. The release of free fatty acid involves activation of phospholipases and breakdown of membrane phospholipids. AA in particular is considered to mediate pathological processes. The polyunsaturated compound is a precursor of prostaglandins, leukotrienes, and oxygen-derived free radicals [11]. In cerebral ischemia concentrations of free AA of up to 0.5 mM/kg have been found in brain tissue [9].

On the Number of Measurements Necessary to Assess Regional Cerebral Blood Flow by Local Laser Doppler Recordings: A Simulation Study with Data from 45 Rabbits

Laser Doppler fluxmetry may improve the monitoring of cortical blood flow in neurosurgical patients. So far, however, the variability of laser Doppler readings found in the cerebral cortex has prevented a consequent usage of the technique in clinical practice. The current report analyzes the regional variability of laser Doppler readings from experimental animals. Typical frequency histograms of observed flow values display non-Gaussian distributions. A simulation technique is used to assess the number of measuring sites required for valid estimates of regional cortical flow. From a total of 990 local flow measurements from 45 rabbits random samples of sizes between 5 and 100 were repeatedl…

Alterations of regional cerebral blood flow and oxygen saturation in a rat sinus-vein thrombosis model.

Background and Purpose The pathophysiology of sinus-vein thrombosis (SVT) in patients and experimental animals is still poorly understood. This study was designed to examine and further elucidate the pathophysiological sequence of events, especially the relationship between local and regional blood flow and hemoglobin oxygen saturation (HbSO 2 ) detected at identical locations. The use of both parameters as outcome indicators should be compared. Methods SVT was induced by ligation of the superior sagittal sinus (SSS) and slow injection of kaolin-cephalin suspension into the SSS in rats. Regional cerebral blood flow (rCBF) was assessed by laser-Doppler flowmetry together with regional HbSO …

The Cerebral Thrombin System Is Activated after Intracerebral Hemorrhage and Contributes to Secondary Lesion Growth and Poor Neurological Outcome in C57Bl/6 Mice

With increasing evidence for the existence of a cerebral thrombin system, coagulation factor IIa (thrombin) is suspected to influence the pathogenesis of secondary injury progression after intracerebral hemorrhage (ICH). We hypothesized that mechanisms associated with local volume expansion after ICH, rather than blood constituents, activate the cerebral thrombin system and are responsible for detrimental neurological outcome. To test this hypothesis, we examine the local thrombin expression after ICH in a C57BL/6N mouse model in the presence and absence of blood constituents. ICH was established using stereotaxic orthotopic injection of utologous blood (

Effects of hypertonic/hyperoncotic treatment after rat cortical vein occlusion*

Objective To examine the effects of hypertonic/hyperoncotic treatment on physiologic variables and regional cerebral blood flow and to test its neuroprotective efficiency in a model of permanent venous ischemia. Design Randomized prospective study. Setting University research institute. Subjects Adult male Wistar rats, weighing 359 +/- 54 g (n = 38). Interventions Rats were subjected to photochemical occlusion of two adjacent cortical veins. A randomized infusion with vehicle (0.9% NaCl), 10% hydroxyethyl starch 200,000 (HES), or 7.5% saline plus 10% hydroxyethyl starch 200,000 (HHES) was started 30 mins after two-vein occlusion. Effects on physiologic variables and regional cerebral blood …

A nonlinear biomechanical model for evaluation of cerebrospinal fluid shunt systems.

In view of complications arising from physical properties of cerebrospinal fluid shunts, a biomechanical model of hydrocephalus was set up to study in vivo parameters that may influence their function. These include: intracranial pressure, compliance and pulses, intrathoracic, intra-abdominal, and subcutaneous pressures, and the effects of siphonage and repeated valve flushing. Each of these factors was studied separately upon shunt implantation in the model. Results of testing of a sample low-pressure valve with antisiphon device conformed with consumer information in regard to valve opening pressure and pressure flow measurements. No customer information, however, was supplied concerning …

Photodynamic therapy within edematous brain tissue: Considerations on sensitizer dose and time point of laser irradiation

Photosensitizer is known to spread with vasogenic edema fluid arising from a cerebral lesion (Neurosurg 33:1075-1082, 1993), which may be essential for sensitizing malignant cells outside the main tumor mass. The present experiments seek to elucidate whether resultant necrosis of perifocal brain tissue after laser irradiation follows a corresponding time pattern and whether damage depends on the photosensitizer dose. Male Wistar rats were anaesthetized with chloralhydrate for venous cannulation, craniotomy and focal cold lesion in order to induce vasogenic edema. Simultaneously, Photofrin II (PF II) was administered at a dose of 5 mg kg-1. The animals were re-anaesthetized after either 4, 1…

Moderate controlled cortical contusion in pigs: effects on multi-parametric neuromonitoring and clinical relevance.

Over the last decade, routine neuromonitoring of ICP and CPP has been extended with new on-line techniques such as microdialysis, tissue oxygen (ptiO(2)), acid-base balance (ptiCO(2), pH) and CBF measurements, which so far have not lead to clear-cut therapy approaches in the neurointensive care unit. This is partially due to the complex pathophysiology following a wide-range of brain injuries, and the lack of suitable animal models allowing simultaneous, clinically relevant neuromonitoring under controlled conditions. Therefore, a controlled cortical impact (CCI) model in large animals (pig) has been developed. After placement of microdialysis, ptiO(2), temperature and ICP catheters, an uni…

On the number of measurement sites required to assess regional cerebral blood flow by laser-Doppler scanning during cerebral ischemia and reperfusion.

The aim of this study was to determine whether the number of measurement sites affected the precision of regional cerebral blood flow (CBF) assessment by Laser-Doppler (LD). A simulation study was applied based on data obtained by scanning the cortex in 25 rats during baseline conditions, 15 min global cerebral ischemia and reperfusion. Random samples were repeatedly collected from 1 to 100 locations and deviations from the median of the entire CBF data pool (800 locations) were determined. Single location CBF measurements missed the true median by 24.8+/-2.2 LD-units (baseline conditions, n=100 simulations, mean+/-SEM), 2.7+/-0.6 LD-units (ischemia), and 31.9+/-2.4 LD-units (30th min reper…

Quantitative Topography of the Hemodynamic-Oxidative Metabolic Interrelation by Multispot Measurement Approach in Rat Ischemia Models

We applied the multispot measurement approach for both laser Doppler (LD) and a microspectrophotometric method to measure local cerebral blood flow (1CBF) and local tissue hemoglobin oxygenation (IHbO2). We demonstrated that the current technology permits in vivo observation, allowing us to establish a close topographical relation between CBF and HbO2. We measured 1CBF by LD flowmetry and tissue HbO2 by a microspectrophotometric method at multiple corresponding locations using a “scanning” technique that employs a computer-controlled micromanipulator. CBF and HbO2 data from predefined locations were correlated to the topographical situation and then arranged in a three-dimensional (3D) imag…

Brain Oedema and Intracranial Pressure in Superior Sagittal Sinus Balloon Occlusion. An Experimental Study in Pigs

About 2/3 of all patients with thrombosis of the superior sagittal sinus (SSS) develop signs of increased ICP and/or brain oedema (BE). The time of onset and the spectrum of symptoms in SSS thrombosis vary extremely. This variability might be caused by differences in pathomechanism like BE and rise of ICP, parameters studied in the present contribution.

Sub-cellular tumor identification and markerless differentiation in the rat brain in vivo by multiphoton microscopy

Objective/Background Aim of the current study was to localize and differentiate between tumor (glioma) and healthy tissue in rat brains on a cellular level. Near-infrared multiphoton microscopy takes advantage of the simultaneous absorption of two or more photons to analyze various materials such as cell and tissue components via the observation of endogenous fluorophores such as NAD(P)H, FAD, porphyrins, melanin, elastin, and collagen, with a very high resolution, without inducing the problems of photo-bleaching on out-of-focus areas. Methods In vitro and in vivo studies on healthy rat brains as well as C6 glioma cell line allografts have been performed. Near-infrared laser pulses (λ = 690…

Inhibition of lactate export by quercetin acidifies rat glial cells in vitro

The relationship between glial lactate release and glial intracellular pH (pH i) regulation is studied using C6 glioma cells and rat astrocytes in vitro, and the lactate transport inhibitors quercetin and a-cyano-4-hydroxycinnamate (CHC). pHi is measured using 2′,7′bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). The results show that lactate release is mediated partly by a specific lactate transport system inhibitable by quercetin (50 mM), but not by CHC (5 mM). Inhibition by quercetin results in a significant 3‐4-fold increase of intracellular lactate and a decrease of intracellular pH to 6.9. A participation of quercetin-inhibitable lactate transport in glial pHi-regulation is suggested…

Pharmacological preconditioning in global cerebral ischemia

Single dose 3-nitropropionic acid (3-NPA) 24 hr before global ischemia improves neuronal survival in both, neocortex and hippocampus (‘chemical preconditioning’). Neuronal survival after transient global ischemia requires new protein synthesis during recovery, especially of those with anti-apoptotic function. Bcl-2-protein is expressed in neurons that survive cerebral ischemia and may parallel the time course of tolerance after ischemic preconditioning. With this study we examined whether differences in bcl-2-protein expression compared to baseline may be involved in the induction of ischemic tolerance using 3-NPA.

Enhanced Interleukin-1β Release and Longevity of Glioma-associated Peripheral Blood Monocytes in Vitro

Interleukin-1 (IL-1) plays a controversial role in the immune response. Besides its activation of immune cells and juvenile central nervous system cells, monocyte-derived IL-1 may be able to stimulate the malignant transformation and proliferation of glial brain tumor cells expressing IL-1 receptors. The aim of this study was to determine the growth pattern and the IL-1 beta release of long-term cultured peripheral blood monocytes of glioma patients. At 6- to 7-day intervals, the vital monocytes, characterized by CD14 immunophenotyping, were counted. By the use of a specific IL-1 beta enzyme-linked immunosorbent assay, the IL-1 beta content of monocyte culture supernatants derived from 13 s…

Resistance of the internal mammary artery to restenosis: a histomorphologic study of various porcine arteries.

<i>Background/Aims:</i> Restenosis after percutaneous transluminal angioplasty (PTA) of the internal mammary artery (IMA) grafts is much less pronounced than in other arteries and venous grafts. The aim of the study was to test whether various arteries respond differently to dilatation. <i>Methods:</i> PTA of the IMA, carotid, renal and circumflex coronary (RCx) arteries was performed in 9 pigs (balloon to artery ratio of 1:1.5). After 8 weeks, angiography was repeated and vessels prepared for histological analysis. Immunohistochemical staining was done to examine proliferative activity (Ki67) and to identify the vasa vasorum of the adventitia (F VIII-RA). <i>R…

Modelling of the Ischemic Penumbra

What happens to the ischemic penumbra – defined as a territory of critically reduced blood flow in the close neighborhood of an ischemic core – determines outcome after stroke. Currently the pathophysiology of the penumbra is studied predominantly in rat models with occlusion of the middle cerebral artery. Here we propose two other rat models with distinct advantages. One produces a large territory of critical flow reduction in the cortex of one hemisphere without presence of an infarct core: this model is suited to study mediator mechanisms that may transform the penumbra into necrotic tissue. It is produced by occluding one carotid artery and in addition reducing arterial pressure to 50mm…

Correlation of cerebral blood flow and MCA flow velocity measured in healthy volunteers during acetazolamide and CO2 stimulation

Abstract The assessment of the cerebrovascular reserve capacity (RC) has become a widely used tool in the management of cerebrovascular disease. Discrepancies become obvious, however, if results obtained with different methods are compared. Aim of the present study, therefore, was to compare blood velocity and cerebral perfusion data in the same group of healthy test persons. In 32 volunteers regional cerebral blood flow (rCBF) was measured with the 133 Xe-inhalation method. F1 as grey matter flow and the initial slope index (ISI) were computed. Simultaneously flow velocity in the middle cerebral artery (V MCA ) was assessed by transcranial Doppler sonography (TCD). Measurements were perfor…

Cerebral protection against ischemia by locomotor activity in gerbils. Underlying mechanisms.

Background and Purpose A previous communication of this laboratory demonstrated reduced mortality and neuronal damage by spontaneous locomotor activity preceding forebrain ischemia in Mongolian gerbils. The present experiments seek to elucidate potential mechanisms of protection by measurement of cerebral blood flow, cerebral tissue conductance as an indicator of ischemic cell swelling, and the cerebral release of eicosanoids. Methods Gerbils were maintained either in conventional cages (nonrunners) or with free access to running wheels (runners) for 2 weeks preceding 15 minutes of forebrain ischemia. During ischemia and 2.5 hours of reperfusion, cerebral tissue conductance was determined …

An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells

Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concent…

Significant correlations between certain spectra of atmospherics and different biological and pathological parameters.

Atmospherics are very short naturally occurring electromagnetic impulses of between 4 and 50 kHz. In this review we summarize our results concerning the correlations between certain spectra of atmospherics and several biological and pathological parameters.

Comparison of the quantitative first pass myocardial perfusion MRI with and without prospective slice tracking: Comparison between breath-hold and free-breathing condition

Physiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion-MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs…

Intrahematomal Ultrasound Enhances RtPA-Fibrinolysis in a Porcine Model of Intracerebral Hemorrhage

Catheter-based ultrasound-thrombolysis has been successfully used in a small clinical trial in order to enhance recombinant tissue plasminogen activator (rtPA)-fibrinolysis, for the treatment of spontaneous intracerebral hemorrhages (ICHs). The aim of this study was to investigate the ultra-early effects of ultrasound on hematoma and the surrounding brain tissue in a porcine ICH-model. To achieve this, 21 pigs with a right frontal ICH were randomly assigned to four groups: (1) drainage (n = 3), (2) drainage + rtPA (n = 6), (3) drainage + ultrasound (n = 6), and (4) drainage + ultrasound + rtPA (n = 6). The hematoma volume assessment was performed using cranial MRI before and after the treat…

Blood constituents trigger brain swelling, tissue death, and reduction of glucose metabolism early after acute subdural hematoma in rats

Outcome from acute subdural hematoma is often worse than would be expected from the pure increase of intracranial volume by bleeding. The aim was to test whether volume-independent pathomechanisms aggravate damage by comparing the effects of blood infusion with those of an inert fluid, paraffin oil, on intracranial pressure (ICP), cerebral perfusion pressure (CPP), local cerebral blood flow (CBF), edema formation, glucose metabolism ([18F]-deoxyglucose, MicroPET), and histological outcome. Rats were injured by subdural infusion of 300 μL venous blood or paraffin. ICP, CPP, and CBF changes, assessed during the first 30 mins after injury, were not different between the injury groups at most …

Inhibition of the myosin light chain kinase prevents hypoxia-induced blood-brain barrier disruption

Increased mortality after stroke is associated with development of brain edema. The aim of the present study was to examine the contribution of endothelial myosin light chain (MLC) phosphorylation to hypoxia-induced blood-brain barrier (BBB) opening. Measurements of trans-endothelial electrical resistance (TEER) were performed to analyse BBB integrity in an in vitro co-culture model (bovine brain microvascular endothelial cells (BEC) and rat astrocytes). Brain fluid content was analysed in rats after stroke induction using a two-vein occlusion model. Dihydroethidium was used to monitor intracellular generation of reactive oxygen species (ROS) in BEC. MLC phosphorylation was detected using i…

Histological Findings in Coil-packed Experimental Aneurysms 3 Months after Embolization

ABSTRACT OBJECTIVE Knowledge regarding tissue reactions within coil-packed aneurysms is poor. The purpose of this study was to analyze histological changes in a chronic experimental bifurcation aneurysm model that might explain the protective effect of Guglielmi detachable coils. METHODS The aneurysms were produced by means of a venous graft pouch at a surgically created bifurcation of the carotid artery in the neck of rabbits. After 3 weeks, embolization with Guglielmi detachable coils was performed in the treatment group but not in the control group (seven rabbits each). At the time of embolization, six of seven treated aneurysms were completely occluded according to radiological criteria…

Glial Swelling and Damage by Arachidonic Acid

Arachidonic acid (AA) is a major constituent of membrane phospholipids in brain tissue. Normally, the free fatty acid is present only in small amounts, but it accumulates under adverse conditions such as ischemia (Kinouchi et al. 1990). The release of free fatty acids involves activation of phospholipases and breakdown of membrane phospholipids. A A in particular is considered to mediate pathological processes. It is a polyunsaturated compound and precursor of prostaglandins, leukotrienes, and oxygen-derived free radicals (Wolfe 1982). In cerebral ischemia concentrations of free AA of up to 0.5mM/kg were found (Kinouchi et al. 1990). But also brain injury and seizures cause increased levels…

Low-frequency ultrasound induces nonenzymatic thrombolysis in vitro.

To evaluate whether ultrasound, applied over a distance of several centimeters and in the absence of thrombolytic agents, may have a thrombolytic effect on blood clots.Low-frequency (20 kHz) continuous wave ultrasound at different intensity levels (0.15-1.2 W/cm2) and exposure times (5, 10, and 20 minutes) was assessed for its potential to induce thrombolysis of fresh human blood clots. The ultrasound effect was also studied in combination with recombinant tissue-type plasminogen activator-mediated thrombolysis. Experiments were carried out in a flow model in degassed sodium phosphate buffer at 37 degrees C at a distance of 3 cm from the ultrasonic probe to the blood clots. Regardless of ul…

An early bolus of hypertonic saline hydroxyethyl starch improves long-term outcome after global cerebral ischemia.

Objective: The beneficial effect of hypertonic saline solutions in the emergency treatment of shock and traumatic brain injury is well described. The present study determines effects of a single bolus of hypertonic saline on long-term survival, neurologic function, and neuronal survival 10 days after global cerebral ischemia. In addition, we evaluated the therapeutic window for hypertonic saline treatment (early vs. delayed application). Design: Laboratory experiment. Setting: University laboratory. Subjects: Male Wistar rats weighing 240‐330 g. Interventions: Rats were submitted to temporal global cerebral ischemia using temporary bilateral carotid occlusion combined with hypobaric hypoten…

Mapping brain activity with flexible graphene micro-transistors

arXiv:1611.05693v1.-- et al.

New method of bone reconstruction designed for skull base surgery

The direct endonasal or transoral transclival approaches to the skull base permit effective, minimally invasive surgery along the clivus. Developing long-term, effective techniques to prevent cerebrospinal fluid (CSF) leaks and their consequences (infection and delayed healing) remains a major challenge. In this study we describe a method of bone reconstruction newly developed by us, which uses a custom designed silicone plug for bone replacement after minimally invasive skull base surgery with a low incidence of postoperative CSF leaks. German Landrace pigs were used to test the efficiency of the new technique. Twelve craniotomies were performed in six pigs using a subtemporal approach and…

Chapter 6: Swelling of C6 glioma cells and astrocytes from glutamate, high K+ concentrations or acidosis

Publisher Summary With impaired energy supply, cell swelling results from the failure of Na+/K+-ATPase according to the pump-leak model of cell volume regulation. In a series of in vitro studies, glial cell volume changes during defined and strictly controlled alterations of the extracellular environment in vitro. Experiments were performed with C6 glioma cells and astrocytes from primary culture. The major advantages of using C6 cells are the rapid availability of large cell numbers necessary for reliable flow cytometric volume measurements, and the homogeneous cell size distribution permitting the detection of even subtle volume changes. The sodium-potassium pump was blocked by the cardia…

Microcirculation after cerebral venous occlusions as assessed by laser Doppler scanning.

✓ Research on cerebral venous circulation disturbances (CVCDs) has been limited partly by the paucity of animal models that produce consistent venous infarction. Occlusion of two adjacent cortical veins in rats by means of a photochemical thrombotic technique provides a minimally invasive, clinically relevant, and reproducible model suited to study the pathophysiology of CVCDs. In this study, the effects of venous occlusion on regional cortical blood flow and the brain damage that ensues were evaluated. Cortical vein occlusion was induced by photoactivation of rose bengal via 100-µm fiberoptic illumination. The cerebral venous flow pattern was examined using fluorescence angiography until 9…

Kinetics of Photofrin II in perifocal brain edema.

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was ind…

Glutamate-containing parenteral nutrition doubles plasma glutamate: A risk factor in neurosurgical patients with blood-brain barrier damage?

OBJECTIVES: Animal studies have shown that the elevation of plasma glutamate levels increase cerebral edema formation whenever the blood-brain barrier is disturbed. Therefore, changes in plasma glutamate levels as influenced by the administration of a glutamate-containing amino acid solution were investigated in neurosurgical patients. DESIGN: Prospective, descriptive study. SETTING: Eight-bed neurosurgical intensive care unit in a university hospital. PATIENTS: Twenty-three neurosurgical patients requiring parenteral nutrition. INTERVENTIONS: Parenteral nutrition was begun 24 hrs after craniotomy. Patients receiving a glutamate-containing amino acid solution (3.75 g/L glutamate) were compa…

Temporal profile of gene induction after venous ischemia accompanied by spreading depression as compared to spreading depression alone

Abstract The occlusion of two adjacent cortical veins is followed by a widespread reduction of rCBF and the occurrence of small infarcts, which become larger if spreading depression (SD) occurs. The model appears to be useful for studying penumbra pathophysiology. Here, the time course of gene expression in the penumbra was compared to those induced by the SD alone. In an experiment involving rats, an occlusion of two cortical veins was induced by i.v. rose bengal and fiberoptic illumination. Ten SDs were induced at 7-min intervals. Changes of the gene expression after 2, 8, 24 and 72 h were analysed for 13 genes by RT-PCR. The housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAP…

Tightness of duraplasty in rabbits: a comparative study.

OBJECTIVE: The purpose of this study was to test, in rabbits, the tightness of seven dural substitution materials commonly used in neurosurgery, i.e., Lyodura (B. Braun Melsungen AG, Melsungen, Germany), Tutoplast dura (Tutogen Medical, Inc., Parsippany, NJ), Tutoplast fascia lata (Tutogen Medical, Inc.), autologous periosteum, Neuropatch (B. Braun Melsungen AG), Dacron (E.I. du Pont de Nemours and Co., Wilmington, DE), and Ethisorb (Ethicon, Inc., Somerville, NJ). METHODS: Duraplasties were performed with sutures alone or were additionally fixed with fibrin glue. Leakage pressures were assessed by infusion of artificial cerebrospinal fluid, containing sodium fluorescein, into the cisterna …

MitoKATP-channel opener protects against neuronal death in rat venous ischemia.

OBJECTIVE: Mitochondrial adenosine triphosphate-dependent potassium (mitoK ATP ) channels are present in the brain, and several reports have shown their neuroprotective, preconditioning effect against an ischemic insult. The role of mitoK ATP channels in the penumbra area has not been studied thoroughly. In a model of venous ischemia, widespread penumbra-like low flow areas are created, which are susceptible to cortical spreading depression. Thus, we studied effects of mitoK ATP channels on infarct size in this model. METHODS: Male Wistar rats were subjected to two-vein occlusion by photochemical thrombosis of two adjacent cortical veins combined with KCI-induced cortical spreading depressi…

Capillary flow and diameter changes during reperfusion after global cerebral ischemia studied by intravital video microscopy.

The reaction of cerebral capillaries to ischemia is unclear. Based on Hossmann's observation of postischemic “delayed hypoperfusion,” we hypothesized that capillary flow is decreased during reperfusion because of increased precapillary flow resistance. To test this hypothesis, we measured cerebral capillary erythrocyte velocity and diameter changes by intravital microscopy in gerbils. A cranial window was prepared over the frontoparietal cortex in 26 gerbils anesthetized with halothane. The animals underwent either a sham operation or fifteen minutes of bilateral carotid artery occlusion causing global cerebral ischemia. Capillary flow velocities were measured by frame-to-frame tracking of…

Temporal and Spatial Evolution of Cortical Blood Flow in the Penumbra of Venous Infarcts

A cortical venous infarction model has been evaluated regarding the temporal and spatial evolution of regional flow reduction. Two cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. After two-vein occlusion, there was a widespread reduction of flow that gradually deteriorated after vein occlusion when regional cortical flow in a 3.5 x 7.0 mm window: after 15 min it had decreased to 57.8% ± 8.0%, and after 75 min it was 34.3% ± 5.4%. Infarct volumes as determined in 10 rats 5 days after two-vein occlusion had an average size of 3.6 ± 0.7 mm3. The data…

Anoxia in vitro does not induce neuronal swelling or death

To improve the understanding of neuronal cell swelling in cerebral ischemia, cell volume regulation, viability, intracellular electrolytes, and lactate production of Neuro-2A neuroblastoma cells were studied using an in vitro model. The volume regulatory capacity of Neuro-2A cells was assessed after incubation in hypo- and hypertonic media. Anoxia was studied alone and together with inhibition of glycolysis by iodoacetate. Reducing the tonicity of the incubation medium to 250, 200, or 150 mosm/l caused immediate swelling followed by a regulatory volume decrease within 20 min, which, however, was not complete. The final cell volume after regulation depended on the tonicity of the medium and …

The Hemodynamic Effects of Ephedrine on the Onset Time of Rocuronium in Pigs

Several studies have found a correlation between the onset time of muscle relaxants, cardiac index, and muscle blood flow. Ephedrine increases these hemodynamic variables and shortens onset time of rocuronium in humans. Our aim in this animal study was to determine the effect of ephedrine on the onset time of rocuronium, cardiac index, and muscle blood flow after administration of thiopental. At predefined measuring points, mean arterial blood pressure and cardiac index were measured invasively and onset time was determined mechanomyographically. Twenty-four pigs were randomly assigned to three groups. Group I received etomidate and subsequently rocuronium (2 x 95% effective dose). Instead …

Cerebral blood flow autoregulation during hypobaric hypotension assessed by laser Doppler scanning.

Hypobaric hypotension was used to reduce systemic blood pressure in rats below the lower threshold of CBF autoregulation to evaluate a new laser Doppler (LD) “scanning” technique. Spontaneously breathing male Wistar Kyoto rats (n = 8) were anesthetized with chloral hydrate and the head fixed in a stereotaxic head holder. A cranial window with intact dura mater was introduced to assess local CBF (lCBF) by LD. One stationary probe served to detect rapid flow changes, whereas the second probe was used to sample lCBF recordings from many cortical locations by means of a stepping motor-controlled micromanipulator to obtain lCBF frequency histograms. Advantages are an improved spatial resolution…

Neuroprotective effect of ceftriaxone on the penumbra in a rat venous ischemia model.

Glutamate transporter-1 (GLT-1) maintains low concentrations of extracellular glutamate by removing glutamate from the extracellular space. It is controversial, however, whether upregulation of GLT-1 is neuroprotective under all ischemic/hypoxic conditions. Recently, a neuroprotective effect of preconditioning with a β-lactam antibiotic ceftriaxone (CTX) that increases expression of GLT-1 has been reported in animal models of focal ischemia. On the other hand, it is said that CTX does not play a neuroprotective role in an in vitro study. Thus, we examined the effect of CTX on ischemic injury in a rat model of two-vein occlusion (2VO). This model mimics venous ischemia during, e.g. tumor sur…

Summary Background. Photodynamic therapy (PDT) has been under dis- cussion as additional treatment option for malignant gliomas. How- ever, damage not only to tumour tissue but also to normal brain has been demonstrated. The mechanisms of this unwanted side eect have not yet been clearly identified. Spreading of photosensitiser with oedema after disruption of the blood-brain-barrier and poten- tial sensitisation of normal tissue has been foundpreviously. The present study investigates the time- and dose-dependency of normal tissue damage to photodynamic therapy using Photofrin II9 after disruption of the blood-brain-barrier. Methods. Male wistar rats anaesthetisedwith chloral hydrate were s…

Caspase-dependent cell death involved in brain damage after acute subdural hematoma in rats

Abstract Traumatic brain injury is associated with acute subdural hematoma (ASDH) that worsens outcome. Although early removal of blood can reduce mortality, patients still die or remain disabled after surgery and additional treatments are needed. The blood mass and extravasated blood induce pathomechanisms such as high intracranial pressure (ICP), ischemia, apoptosis and inflammation which lead to acute as well as delayed cell death. Only little is known about the basis of delayed cell death in this type of injury. Thus, the purpose of the study was to investigate to which extent caspase-dependent intracellular processes are involved in the lesion development after ASDH in rats. A volume o…

Effect of chest compressions only during experimental basic life support on alveolar collapse and recruitment

Summary Aim The importance of ventilatory support during cardiac arrest and basic life support is controversial. This experimental study used dynamic computed tomography (CT) to assess the effects of chest compressions only during cardiopulmonary resuscitation (CCO-CPR) on alveolar recruitment and haemodynamic parameters in porcine model of ventricular fibrillation. Materials and methods Twelve anaesthetized pigs (26±1kg) were randomly assigned to one of the following groups: (1) intermittent positive pressure ventilation (IPPV) both during basic life support and advanced cardiac life support, or (2) CCO during basic life support and IPPV during advanced cardiac life support. Measurements w…

C1-Esterase-Inhibitor Treatment at Early Reperfusion of Hemorrhagic Shock Reduces Mesentery Leukocyte Adhesion and Rolling

Objective: Complement activation probably plays a pathogenic role in multiple organ failure in shock. This study evaluates the effects of C1-esterase-inhibitor treatment on leukocyte-endothelial interaction in the mesenteric microcirculation in hemorrhagic shock. Methods: Rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Volume controlled hemorrhagic shock was provoked by arterial blood withdrawal (2.5 mL/ 100 g body wt. for 60 minutes) followed by a 4-hour reperfusion period. C1-INH (100 IU/kg body wt. i.v.) or 0.9% NaCl i.v. were administered as a bolus at the beginning of reperfusion. Reperfusion time mimic…

C1-esterase inhibitor reduces infarct volume after cortical vein occlusion.

In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood flow (rCBF) decreased after occlusion, and was about 50% of baseline after 2 h. No difference was noted between experimental groups. Mean arterial blood pressure (MABP) and arterial blood gases were likewise unaffected by the treatment. However, administration of C1-INH had significantly reduced infarct volume by 72%, as evaluated after 5 days survival…

In vivo molecular and morphological imaging by real time confocal mini-microscopy

We evaluated a newly developed miniaturized confocal laser microscopy probe for real-time in vivo molecular and morphological imaging of normal, inflammatory, and malignant tissue in rodents. In the rigid mini-microscopy probe (diameter 7 mm), a single line laser delivers an excitation wavelength of 488 nm. Optical slice thickness is 7 μm, lateral resolution 0.7 μm. The range of the z-axis is 0 - 250 μm below the tissue surface. Organ systems were examined in vivo in rodent models of human diseases. FITC-labeled Lycopersion esculentum lectin was injected or selected cell populations stained for molecular targeting. Morphological imaging was performed using fluorescein sodium, FITC-labeled d…

Early-onset tolerance in rat global cerebral ischemia induced by a mitochondrial inhibitor

It was studied whether a subtoxic dose of the mitochondrial neurotoxin, 3-nitropropionic acid (3-NPA), can initiate early-onset tolerance induction for subsequent ischemic injury. Wistar rats were pretreated for 3 h by intraperitoneal 3-NPA (20 mg/kg body weight; n=13) or solvent (n=12). Fifteen minutes global cerebral ischemia was induced by bilateral carotid artery occlusion and hypobaric hypotension. rCBF and tissue hemoglobin oxygen saturation were measured by laser Doppler scanning and a microspectrophotometric method. Ischemic insult and brain temperature were identical in both groups. Body weight and neurological scores recovered in the pretreated group but further deteriorated in th…

Acute Subdural Hematoma in Pigs: Role of Volume on Multiparametric Neuromonitoring and Histology

Traumatic brain injury (TBI) is often complicated by acute subdural hemorrhage (ASDH) with a high mortality rate. The pathophysiological mechanisms behind such an injury type and the contribution of blood to the extent of an injury remain poorly understood. Therefore, the goals of this study were to establish a porcine ASDH model in order to investigate pathomechanisms of ASDH and to compare effects induced by blood or sheer volume. Thus, we infused 2, 5, and 9 mL of blood (up to 15% of intracranial volume), and we compared a 5-mL blood and paraffin oil volume to separate out effects of extravasated blood on brain tissue. An extended neuromonitoring was applied that lasted up to 12 h after …

Erythropoietin neuroprotection is enhanced by direct cortical application following subdural blood evacuation in a rat model of acute subdural hematoma.

Recombinant human erythropoietin (EPO) has been successfully tested as neuroprotectant in brain injury models. The first large clinical trial with stroke patients, however, revealed negative results. Reasons are manifold and may include side-effects such as thrombotic complications or interactions with other medication, EPO concentration, penetration of the blood-brain-barrier and/or route of application. The latter is restricted to systemic application. Here we hypothesize that EPO is neuroprotective in a rat model of acute subdural hemorrhage (ASDH) and that direct cortical application is a feasible route of application in this injury type. The subdural hematoma was surgically evacuated a…

Temporal Profile of Gene Induction After Venous Ischemia and Effects of Spreading Depression

Occlusion of two adjacent cortical veins is followed by a widespread reduction of rCBF and the occurrence of small infarcts, which become larger if spreading depression (SD) occurs. The infarct matures over time with TUNEL-positive cells seen in the penumbra up to 4 days after vein occlusion. Caspase inhibition with zVAD.fmk reduces infarct size. Here, the time course of gene expression in the penumbra is compared to that induced by SD alone.

Spontaneous Cortical Spreading Depression and Intracranial Pressure Following Acute Subdural Hematoma in a Rat

Acute subdural hemorrhage (ASDH) is a frequent and devastating consequence of traumatic brain injury. Tissue damage develops rapidly and makes treatment even more difficult. Management of increased intracranial pressure (ICP) due to extravasated blood volume and brain swelling is often insufficient to control all adverse effects of ASDH. In addition to sheer volume, spontaneously triggered cortical spreading depression (CSD) that leads to cell death following ischemia or trauma may contribute to injury development after ASDH. Therefore, we explored the occurrence of CSD by tissue impedance (IMP) measurement in a rat model subjected to ASDH. IMP and intraventricular and mean arterial pressur…

Swelling, Acidosis, and Irreversible Damage of Glial Cells from Exposure to Arachidonic Acid in vitro

Swelling and damage of C6 glioma cells and of primary cultured astrocytes were analyzed in vitro during incubation with arachidonic acid (AA; 20:4). The cells were suspended in a physiological medium supplemented with AA at concentrations of 0.001–1.0 m M. Cell swelling was quantified by flow cytometry with hydrodynamic focusing. Flow cytometry was also utilized for assessment of cell viability by exclusion of the fluorescent dye propidium iodide and for measurement of the intracellular pH (pHi) by 2′,7′-bis-(2-carboxyethyl)−5(and −6)carboxyfluorescein. Administration of AA caused an immediate dose-dependent swelling of C6 glioma cells, even at a concentration of 0.01 m M. At this level cel…

Occlusion of the pig superior sagittal sinus, bridging and cortical veins: multistep evolution of sinus-vein thrombosis

✓ Cerebral sinus-vein thrombosis may lead to severe hemodynamic changes, elevated intracranial pressure (ICP), and brain edema. It is supposed that progression of the thrombus from the sinus into bridging and cortical veins plays a key role in the development of these pathophysiological changes, but this hypothesis lacks experimental proof. The aim of this study, using a novel animal model of sinus-vein thrombosis, was to evaluate the effects of a standardized occlusion of the superior sagittal sinus and its bridging and cortical veins on hemodynamic alterations, on brain water content, and on ICP in domestic pigs. In 10 animals, the middle third of the superior sagittal sinus was occluded …

Glutamate Enhances Brain Damage from Ischemia and Trauma

The amino acid glutamate is a model agent to demonstrate the significance of neurotoxic mediator compounds in secondary brain damage from trauma, ischemia or other adverse conditions. Intensive research of the role of mediator compounds is clinically worthwile as more specific forms of treatment may emerge for the benefit of afflicted patients. In view of the great number of factors, cytokines, etc., which could play a role, it is mandatory that a mediator function in secondary brain damage is identified according to the stringent requirements established for that purpose. Glutamate has been shown — as is the case for only a few other agents — to meet all the criteria of a mediator of secon…

The objective was to study the effects of a lung recruitment procedure by stepwise increases of mean airway pressure upon organ blood flow and hemodynamics during high-frequency oscillatory ventilation (HFOV) versus pressure-controlled ventilation (PCV) in experimental lung injury. Lung damage was induced by repeated lung lavages in seven anesthetized pigs (23–26 kg). In randomized order, HFOV and PCV were performed with a fixed sequence of mean airway pressure increases (20, 25, and 30 mbar every 30 minutes). The transpulmonary pressure, systemic hemodynamics, intracranial pressure, cerebral perfusion pressure, organ blood flow (fluorescent microspheres), arterial and mixed venous blood ga…

BCL-2 UPREGULATION AFTER 3-NITROPROPIONIC ACID PRECONDITIONING IN WARM RAT LIVER ISCHEMIA

We aimed to determine whether 3-nitropropionic acid (3-NPA) preconditioning protects rat livers against warm ischemia/reperfusion injury. We hypothesized that 3-NPA mediates its protective effects by Bcl-2 upregulation. Brown-Norway rats (200 g) were injected with 3-NPA (10 mg/kg intraperitoneally) 24 h before 90 min of selective warm in situ ischemia. In additional experiments, 30-day survival was studied after 90 min of warm liver ischemia and resection of nonischemic liver tissue. We demonstrate increased mRNA and protein levels of Bcl-2 by real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis in 3-NPA-pretreated rats. All treated animals survived, whereas …

Postischemic application of lipid peroxidation inhibitor U-101033E reduces neuronal damage after global cerebral ischemia in rats.

Background and Purpose —The lipid peroxidation inhibitor U-101033E was examined for effects on cerebral blood flow (CBF), cortical tissue hemoglobin oxygen saturation (HbS o 2 ), and neuronal damage. Methods —Fifteen minutes of global cerebral ischemia was induced by two-vessel occlusion and hypobaric hypotension. Wistar rats (n=25) were randomized to receive vehicle (n=9) or 40 mg/kg U-101033E (n=9) intraperitoneally during 2 hours of reperfusion. A sham group (n=7) had neither ischemia nor therapy. Histology was evaluated 7 days after ischemia. Results —During late hyperperfusion (at 17 minutes), vehicle-treated animals had a higher ( P =0.044) cortical tissue HbS o 2 (72.0±1.4%) than di…

Local Gingival Blood Flow at Healthy and Inflamed Sites Measured by Laser Doppler Flowmetry

This investigation aimed to: 1) develop a method to obtain reproducible laser Doppler flow readings (LDFRs) at the gingiva of the maxillary front teeth; 2) evaluate regional gingival blood flow (GBF) in healthy gingiva by laser Doppler flowmetry; 3) compare hand-held LDFR (H-LDFR) with splint LDFR (S-LDFR); and 4) monitor changes in GBF in experimental gingivitis (EG) and chronic gingivitis (CG).The LDFR, gingival index (GI), and plaque index (PI) were measured at 13 gingival sites (teeth #6 to #11) in 10 healthy volunteers (five males and five females), 23 to 34 years of age, over a period of 12.5 +/- 3.27 days employing a partial-mouth EG model and in 11 patients (three males and eight fe…

Intracoronary application of C1 esterase inhibitor improves cardiac function and reduces myocardial necrosis in an experimental model of ischemia and reperfusion.

Background Myocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events, including complement activation, leukocyte adhesion, and infiltration and release of diverse mediators, probably play important roles. The present study addresses the possibility of reducing reperfusion damage by the application of C1 esterase inhibitor (C1-INH). Methods and Results Cardioprotection by C1-INH 20 IU/kg IC was examined in a pig model with 60 minutes of coronary occlusion, followed by 120 minutes of reperfusion. C1-INH was administered during the first 5 minutes of coronary reperfusion…

Ultrasound-induced blood clot dissolution without a thrombolytic drug is more effective with lower frequencies.

<i>Background and Purpose:</i> Therapeutic ultrasound as stand-alone therapy or in combination with rt-PA has proven to be an effective measure for recanalisation of acute vessel occlusion in different in vitro and in vivo studies. Uncertainty still exists concerning the optimal frequency and intensity with regard to the thrombolytic efficacy of ultrasound. The purpose of this study was a direct comparison of different ultrasound frequencies, when otherwise using identical measurement settings and parameters. <i>Methods:</i> Ultrasound-induced dissolution of fresh human blood clots was studied in a flow system using low-frequency continuous wave ultrasound of 20, 40 …

The neuroprotective effect of lactate is not due to improved glutamate uptake after controlled cortical impact in rats.

For many years lactate was considered to be a waste product of glycolysis. Data are accumulating that suggest that lactate is an important energy substrate for neurons during activation. In severe traumatic brain injury (TBI) glutamate release and ischemic cerebral blood flow (CBF) are major factors for a mismatch between energy demand and supply and for neuronal cell death. Although ATP and behavior could be improved by lactate treatment after TBI, no histological correlate nor any linkage to better astrocytic glutamate uptake or CBF as possible mechanisms have been described. We subjected male rats to a controlled cortical impact (CCI; 5 m/sec, 2.5 mm). To study the effects of lactate tre…

Brain Edema and Intracerebral Necrosis Caused by Transcranial Low-Frequency 20-kHz Ultrasound

Background and Purpose— Ultrasound-accelerated thrombolysis is a promising approach toward acute stroke treatment. In previous in vitro studies, we demonstrated enhanced thrombus destruction induced by 20-kHz ultrasound. However, little is known about biological interactions of low-frequency ultrasound with brain tissue. The aim of this in vivo MRI study was to assess safety aspects of transcranial low-frequency ultrasound in rats. Methods— The cranium of 33 male Wistar rats was sonificated for 20 minutes (20-kHz continuous wave). Power output was varied between 0 and 2.6 W/cm 2 . Tympanal and rectal temperature was monitored. Diffusion-weighted imaging and T2-weighted imaging was performe…

Plastic foil technique attenuates inflammation in mesenteric intravital microscopy.

Abstract Background. Interpretation of intravital microscopic observations is complicated by the “inflammatory”-type response to the trauma inflicted on the tissue by the surgical preparation. The present study evaluates different experimental conditions for prolonged observations of the mesenteric microcirculation in the rat. Methods. The mesentery was exteriorized through a median laparotomy and subjected to an organ bath or a modified plastic foil technique. Hemodynamic, metabolic, respiratory, and microcirculatory data were analyzed. Results. In contrast to the plastic foil technique, which yielded stable baseline values over a 5-h observation period, venular velocity and wall shear rat…

Therapeutic Application of 20-kHz Transcranial Ultrasound in an Embolic Middle Cerebral Artery Occlusion Model in Rats

Background and Purpose— Therapeutic application of diagnostic ultrasound has been shown to improve recanalization rates in patients with acute cerebral vessel occlusion. There is experimental evidence that low-frequency ultrasound may be superior. This study was designed to evaluate the therapeutic efficacy and safety of low-frequency ultrasound in an embolic middle cerebral artery occlusion model in rats. A parameter setting was used that had not previously shown any side effects and interactions with healthy rat brain tissue. Methods— Male Wistar rats were submitted to middle cerebral artery clot embolism and transcranial treatment with 20-kHz continuous-wave ultrasound (0.2 W/cm 2 ), ei…

Anti-Inflammatory Treatment with Standardized Human Serum Protein Solution Reduces Local and Systemic Inflammatory Response after Hemorrhagic Shock

<i>Objective:</i> Reperfusion after hemorrhagic shock leads to local and systemic inflammatory response. This study evaluates the effect of a short-term treatment with standardized human serum protein solution (SPS) on the local and systemic inflammatory response in the mesenteric microcirculation in the rat. <i>Methods:</i> Spontaneously breathing animals underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Volume-controlled hemorrhagic shock was set by arterial blood withdrawal (2.5 ml/100 g body weight for 60 min), followed by reperfusion for 4 h. SPS (n = 10) or saline 0.9% (controls, n = 1…

“Small Volume Resuscitation” as Treatment of Cerebral Blood Flow Disturbances and Increased ICP in Trauma and Ischemia

“Small volume resuscitation” (SVR) is a promising concept for the treatment of shock and trauma patients. SVR utilizes the fast infusion of a small volume of hypertonic saline to mobilize intraendothelial and parenchymal water to expand and restitute intravascular volume. Therefore it seems warranted to also consider SVR for the treatment of disturbances of the cerebral circulation and of increased intracranial pressure (ICP). The current study uses a rabbit model of global cerebral ischemia combined with mild hemorrhage to test SVR. Somatosensory evoked potentials (SEPs) serve as a short-term outcome parameter. The data demonstrate a beneficial effect on ICP, a better reperfusion, and an i…

Electrical Impedance, ICP and Histology in Rats with Sagittal Sinus Occlusion

The diversity of clinical symptoms developing after thrombosis of the cerebral superior sagittal sinus is not well understood [2, 4], This is largely related to our ignorance of the underlying pathophysiology. An improvement in the pathophysiological understanding can be expected by experimental studies. Although animal models are available fot that purpose they are, however, in short supply. A few years ago, our laboratory in collaboration with the department of neurology at the University of Munich made another attempt to establish a reproducible experimental model for the induction of thrombosis of the superior sagittal sinus in rats. In the present studies this model has been used to ev…

Resection of C6 gliomas in rats with the aid of the waterjet technique

While clinically the safety and efficacy of waterjet resection of brain tumors have been shown, evidence that waterjet dissection improves tumor resection radicality in comparison with conventional techniques is still missing. In the present study, resection radicality and tumor-free long-term survival of both techniques were evaluated in a C6-glioma model.Fifty-thousand C6-glioma cells were stereotactically transplanted in the left frontal lobe of 100 male Sprague-Dawley rats. After MRI-scanning for evaluation of tumor extension, microsurgical tumor resection was performed with conventional techniques (n=50) or with the waterjet dissector at pressures of 6bar (n=50). Twenty-five animals of…

Monitoring of cortical blood flow: Clinical relevance of experimental laser Doppler studies

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve …

Cluster analysis of mrna expression levels identifies multiple sequential patterns following focal cerebral ischemia

AIM The purpose of this study is to detect gene expression patterns following focal cerebral ischemia. MATERIAL AND METHODS 25 male Wistar rats were divided into control (n = 8) and ischemic (n = 17) groups. In the ischemic group, slowly progressing focal ischemia was simulated by two-vein occlusion with spreading depression (SD) a cortical microinjection of KCl induced. Ischemic tissue was removed at 2, 8, 24, or 72 h postischemia. Using semiquantitative reverse transcription polymerase chain reaction, we investigated mRNA expression levels of 13 representative genes related to cerebral ischemia. Cluster analysis of the gene expression levels was done. RESULTS In the ischemic group, the ex…

Is a Mask That Covers the Mouth and Nose Free from Undesirable Side Effects in Everyday Use and Free of Potential Hazards?

International journal of environmental research and public health : IJERPH 18(8), 4344 (2021). doi:10.3390/ijerph18084344

Comparative analysis of fibrinolytic properties of Alteplase, Tenecteplase and Urokinase in an in vitro clot model of intracerebral haemorrhage.

Abstract Objective Hematoma lysis with recombinant tissue plasminogen activator (rtPA) has emerged as an alternative therapy for spontaneous intracerebral and intraventricular haemorrhage (ICH and IVH). However, the MISTIE III and CLEAR III trial failed to show significant improvement of favourable outcomes. Besides experimental and clinical trials revealed neurotoxic effects of rtPA. The demand for optimization of fibrinolytic therapy persists. Herein, we used our recently devised clot model of ICH to systematically analyse fibrinolytic properties of rtPA, tenecteplase and urokinase. Methods In vitro clots of human blood (size: 25 ml and 50 ml; age: 1.5 tenecteplase, 24 tenecteplase and 48…

Secondary Growth of a Primary Brain Tissue Necrosis from a Focal Lesion

Traumatic brain injury is associated with the development of secondary brain damage, such as brain edema, intracranial hypertension, and cerebral ischemia [1]. A novel aspect is that a primary necrosis of brain parenchyma evolving from a focal cerebral insult may be subjected to secondary growth. Experiments utilizing different methods of brain injury have consistently confirmed an increase in size of the resulting tissue necrosis within 24 h, amounting to 50% in rats [3, 7, 10] and even 300% in rabbits [11]. It is not clear yet, however, whether the phenomenon reflects a delayed but irreversible primary process which is resistant to treatment or a manifestation of secondary brain damage, t…

Relationship of Cerebral Blood Flow Disturbances with Brain Oedema Formation

Brain oedema is an important factor which compromises maintenance of the cerebral blood flow. Conversely, primary blood flow disturbances are leading to brain oedema. The mechanisms underlying blood flow impairment by brain oedema are associated with an increased regional tissue pressure in proportion to the degree of water accumulation in the parenchyma. The release of vasoactive mediator compounds might be considered in addition. Primary disturbances of the cerebral blood flow, such as focal or global cerebral ischaemia are leading to an increased cerebral water content. A decrease of the cerebral blood flow to ca. 40% of normal or below has been found to result in the development of brai…

Swelling of glial cells in lactacidosis and by glutamate: significance of Cl(-)-transport.

Swelling of glial and nerve cells is characteristic of brain damage in cerebral ischemia or trauma. The therapeutical efficiency of inhibition of Cl(-)-transport by a novel antagonist, the diuretic torasemide, on cytotoxic swelling of glial cells from lactacidosis, or glutamate was analyzed. Lactacidosis and the interstitial accumulation of glutamate are hallmarks of the pathophysiological alterations in ischemic or traumatic brain tissue. C6 glioma cells harvested from culture and suspended in a physiological medium were either exposed to pH 6.2, or 5.0 by lactic acid, or exposed to 1 mM glutamate at normal pH. Cell swelling and viability were quantified by flow cytometry. Lactacidosis of …

Clearance and metabolism of arachidonic acid by C6 glioma cells and astrocytes.

Effects of increased levels of arachidonic acid (AA) were analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in a physiological medium added with arachidonic acid (AA) in a concentration range from 0.01 to 0.5 mM. The concentration profiles of the fatty acid and AA-metabolites were subsequently followed for 90 min. AA was measured by gas chromatography, whereas the AA-metabolites PGF2 alpha and LTB4 by radioimmunoassay (RIA). Following administration of AA at 0.05 or 0.1 mM the medium was completely cleared from the fatty acid within 10 to 15 min. However, when 0.5 mM were added, AA concentrations of 0.36 +/- 0.055 mM were found …

Relation of early Photofrin uptake to photodynamically induced phototoxicity and changes of cell volume in different cell lines.

For efficacy of photodynamic therapy, selective uptake and retention of photoactive substances has been postulated. Therefore, measurements were performed to find out whether the photosensitiser Photofrin® is taken up differently in malignant and non-malignant cells in vitro . In addition, the sensitivity of malignant cells and nonmalignant cells to photodynamic exposure was investigated, by quantifying viability and volume alterations of the cells. Bovine aortic endothelial cells, mouse fibroblasts and amelanotic hamster melanoma cells were suspended in a specially designed incubation chamber under controlled conditions (e.g. pH, p O 2 , p CO 2 and temperature). After establishing constant…

3-NPA induziert Ischämietoleranz der Rattenleber nach warmer Ischämie

Until now little is known about the potential of 3-nitroproprionic acid (3-NPA) to reduce ischemia/ reperfusion injury (IRI) of the rat liver in vivo.

Total mesorectal excision - does the choice of dissection technique have an impact on pelvic autonomic nerve preservation?

Background The aim of this experimental study was to assess the quality of pelvic autonomic nerve preservation of different dissection techniques.

Significant correlations between certain spectra of atmospherics and daily periodic activities of Mongolian gerbils (Meriones unguiculatus L.).

We describe significant correlations between 10 and 28 kHz atmospherics (according to Baumer) and the running activities of ten Mongolian gerbils (Meriones unguiculatus L.) depending on their circadian rhythm over a 42-day period (August/September 1988).

Shunting of the Microcirculation After Mesenteric Ischemia and Reperfusion Is a Function of Ischemia Time and Increases Mortality

Shunting of the microcirculation contributes to the pathology of sepsis and septic shock. The authors address the hypothesis that shunting of the microcirculation occurs after superior mesenteric artery occlusion (SMAO) and reperfusion, and explore functional consequences.Spontaneously breathing animals (rats) (n = 30) underwent SMAO for 0 (controls), 30 (SMAO_30) or 60 min (SMAO_60) followed by reperfusion (4 h) with normal saline. Leukocyte-endothelial interactions in mesenteric venules were quantified in an exteriorized ileal loop using intravital microscopy. Abdominal blood flow was recorded continuously, and arterial blood gases were analyzed at intervals. The above groups were matched…

Sauerstoffmetabolismus und intramuraler pH des Dünndarms bei mesenterialer Ischämie und Verhalten der Mikrozirkulation nach hyperton-hyperonkotischem Volumenersatz

Der akute Verschlus der A.mesenterica superior (AMS) fuhrt zu einer Ischamie des gesamten Dunndarms. Der Kollateralkreislauf kann mit unterschiedlichen Kompen-sationsmechanismen [2, 4] nur eine minimale und unzureichende Blutversorgung aufrechterhalten. Abhangig von der Ischamiedauer entsteht eine Gewebeschadigung. Bei der Reperfusion ischamischer Darmanteile werden zahlreiche vasoaktive Me-diatoren freigesetzt und eine Schocksituation verursacht, die den gesamten Orga-nismus beeintrachtigt und bei eingeschrankter Zirkulation eine Verlangerung der Darmischamie bewirkt. Die Tonometrie hat sich in einigen experimentellen Ver-suchsanordnungen als geeignete minimal-invasive Masnahme zur Abschat…

Does granulocyte-colony stimulating factor stimulate peripheral nerve regeneration? An experimental study on traumatic lesion of the sciatic nerve in rats.

Aim of the study. To analyse the therapeutic potential of granulocyte-colony stimulating factor (G-CSF) treatment using a rat model of traumatic sciatic nerve lesion. Clinical rationale for the study. G-CSF has proven strong neurotrophic properties in various models of ischaemic and traumatic brain injury. Fewer studies exist regarding the influence of G-CSF on posttraumatic peripheral nerve regeneration. Currently, the possibilities of pharmacological prevention or treatment of mechanical nerve injury are limited, and there is an urgent need to find new treatment strategies applicable in clinical situations. Material and methods . A controlled traumatic right sciatic nerve lesion was set u…

The antibiotic erythromycin induces tolerance against transient global cerebral ischemia in rats (pharmacologic preconditioning).

Background Cerebral ischemic tolerance can be induced by a variety of noxious stimuli, but no clinically applicable regimen for preconditioning has been described. Therefore, the authors tested the ability of a pharmacologic preconditioning strategy using the well-known macrolide antibiotic erythromycin to induce tolerance against transient global cerebral ischemia in vivo. They also investigated whether tolerance induction by erythromycin involves transcriptional and translational changes of cerebral B-cell leukemia/lymphoma-2 (bcl-2) expression. Methods Male Wistar rats were treated with erythromycin (25 mg/kg intramuscularly) or vehicle and subjected to 15 min of transient global cerebr…

Early albumin infusion improves global and local hemodynamics and reduces inflammatory response in hemorrhagic shock.

Objective To evaluate the effects of an early, short-term albumin infusion on mesenteric microcirculation and global hemodynamics in hemorrhagic shock. Design A prospective, randomized study. Setting Animal laboratory at a university medical clinic. Subjects Seventeen Sprague-Dawley rats weighing 250–400 g. Interventions The rats underwent median laparotomy and exteriorization of an ileal loop for intravital microscopy of the mesenteric microcirculation. Volume-controlled hemorrhagic shock was provoked by arterial blood withdrawal (2.5 mL/100 g body weight for 60 mins), followed by a 4-hr reperfusion period. Albumin (20%) or 0.9% NaCl was administered intravenously as a continuous infusion …

Laser Doppler Scanning: How Many Measurements are Required to Assess Regional Cerebral Blood Flow?

This study was initiated to determine the optimal number of measuring sites necessary to estimate regional cerebral blood flow (CBF) under pathophysiological conditions.

Plasmavolumenverschiebung und Veränderungen der zentralen Hämodynamik nach Okklusion der A. mesent. sup. und anschließender Reperfusion

Im Schweinemodell wurde die Veranderung des Plasmavolumens bei verschiedenen therapeutischen Ansatzen des Reperfusionsschocks nach 2-stundiger Okklusion der A. mesent. sup. untersucht (keine Therapie, 5–50 μg Dopamin, 40 ml/kg KG isotone Reperfusion in 30 Min., 5 ml/kg KG 7,5% NaCl/10% HAES in 5 Min.). Der Plasmavolumenverlust von >30% in der Kontroll- und Dopamingruppe wurde nur durch die isotone Reperfusion vollstandig ausgeglichen. Die hyperton/hyperonkotische Therapie (-16% PV-Verlust) wies aber ein signifikant verbessertes HZV auf.

Mechanisms of Glial Swelling by Arachidonic Acid

The effect of arachidonic acid (AA, 20:4) was analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in an incubation chamber under continuous control of pH, pO2, and temperature. Cell swelling was quantified by flow cytometry. After a control period, the suspension was added with AA at concentrations of 0.01 to 1.0 mM. Administration of AA induced an immediate, dose dependent swelling in C6 glioma cells or astrocytes. AA-concentrations of 0.01 mM led to an increase of the glial cell volume to 103.0 ± 1.0% of control, 0.1 mM to 110.0 ± 1.5%, and l.0 mM to 118.8 ± 1.5% within 10 min. The swelling response to linoleic acid (18 : 2) was…

Research and Clinical Routine in the next Century,Segregation or Cooperative Networks?

Reading the daily newspaper one gets the impression that German universities and clinical research in particular are in a deep crisis, and that German professors are to be blamed for it. In medicine, additional insufficiencies of the system are obvious, beginning with corruption cases brought up against clinicians and ending with conflicts of interest due to the fact that clinical professors in addition to research and teaching devote much of their time to the special care of private patients. These headlines in the news tend to let us forget that during the last decade grant moneys for research projects stagnated whereas the number of grant applications has increased out of proportion. In …

Critical single proximal left arterial descending coronary artery stenosis to mimic chronic myocardial ischemia: a new model induced by minimal invasive technology.

<i>Background/Aims:</i> The present report examines a new pig model for progressive induction of high-grade stenosis, for the study of chronic myocardial ischemia and the dynamics of collateral vessel growth. <i>Methods:</i> Thirty-nine Landrace pigs were instrumented with a novel experimental stent (GVD stent) in the left anterior descending coronary artery. Eight animals underwent transthoracic echocardiography at rest and under low-dose dobutamine. Seven animals were examined by nuclear PET and SPECT analysis. Epi-, mid- and endocardial fibrosis and the numbers of arterial vessels were examined by histology. <i>Results:</i> Functional analysis showed a…

Continuous intraoperative monitoring of pelvic autonomic nerves as a microtechnological navigation instrument

Spreading Depression Induces Permanent Cell Swelling Under Penumbra Conditions

Background. Spreading depression (SD) is known to go along with temporary breakdown of ion gradients and cell swelling which spontaneously normalizes. Here, the effects of SD at reduced flow conditions as encountered in the ischemic penumbra are examined.

Cerebral blood flow alterations in a rat model of cerebral sinus thrombosis.

Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats. Thrombosis was induced by slow injection of kaolin-cephalin suspension after frontal and caudal ligation of the sagittal sinus in rats. Local cerebral blood flow was measured by laser Doppler flowmetry and correlated with parenchymal damage found 24 hours after i…

Towards a glioma model for surgical technique evaluation in the rat.

Evaluation of new surgical techniques in animal models is frequently challenging. This article describes the pitfalls, peculiarities and the final best applicable model for evaluating surgical techniques for glioma resection.The C6 glioma cell line and the Sprague-Dawley rat strain were selected. Fifty-thousand glioma cells were stereotactically transplanted in the left hemisphere of 137 male adult rats. Evaluation of solid tumour formation, tumour growth and scheduling of surgical resection was performed by MR scanning at 1, 2, and 4 weeks after transplantation and 3 and 6 months after tumour resection. Microsurgical tumour resection was performed with conventional techniques or with the w…

Nitric oxide modulates cerebral blood flow stimulation by acetazolamide in the rat cortex: a laser Doppler scanning study

Abstract The involvement of nitric oxide (NO) in cerebral blood flow (CBF) stimulation by acetazolamide was studied in anaesthetised, mechanically ventilated Wistar rats. CBF was monitored by laser Doppler scanning. Acetazolamide induced a long-lasting significant rCBF-increase. Application of N G -Nitro- l -arginine (L-NNA), an inhibitor of all NO synthetases (NOS), prevented CBF stimulation by acetazolamide. Continuous infusion of the exogenous NO donor SIN-1 (3-morpholinosydnonimine) suppressed L-NNA induced increases of mean arterial blood pressure without effect on rCBF in comparison to baseline. Additional acetazolamide injection then again caused a significant increase of rCBF in spi…

Significance of resting and stimulated cerebral blood flow for predicting the risk of hemodynamic cerebral ischemia in a model of chronic hemodynamic insufficiency.

OBJECTIVE: It has been postulated that patients with a compromised cerebrovascular reserve capacity (RC), defined as cerebral blood flow (CBF) response to acetazolamide (ACZ) (by percent), are at higher risk for ischemic stroke. The value of CBF and RC for predicting the risk of hemodynamically induced impairment of cerebral function is examined. METHODS: Both common carotid arteries were occluded in 22 Wistar-Kyoto rats. Thirty-one days later, mean arterial blood pressure was reduced to 40 mm Hg for 30 minutes. Laser Doppler scanning of CBF at resting conditions and after intraperitoneal administration of ACZ (0.1 mg/g body weight) was performed 30 minutes and 28 days after occlusion as we…

Flow and Pressure during Liver Preservation under ex situ and in situ Perfusion with University of Wisconsin Solution and Histidine-Tryptophan-Ketoglutarate Solution

Effective preservation of liver grafts is the first essential step for successful liver transplantation. Insufficient perfusion leads to ischemic-type biliary lesions after transplantation. Perfusion of the graft can be performed either in situ or ex situ, with gravity flow or pressure-controlled. Mainly University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) solutions are used widespread in clinical liver transplantation. Due to a persistent lack of data, we performed this systematic investigation of in situ and ex situ perfusion of liver grafts with HTK (low-viscous) and UW (high-viscous) solutions at different pressure steps on the perfusion solution (gravity flow, 50, …

Mechanisms of Cell-Volume Regulation in the Central Nervous System

Function and viability of every cell is dependent on the proper control of its shape and volume. In the brain, which is protected by a rigid outer shell, cell-volume regulation is of particular importance, since large volume changes affect cerebral perfusion and, hence, function. Neuronal activation leads to constant changes of the ionic and metabolic composition of the brain’s extracellular space. These changes are buffered by astrocytes on the expense of constant changes in cell volume. Under pathological conditions, the ability of astrocytes to maintain the homeostasis of the brain is overwhelmed and permanent cell swelling, cytotoxic edema, occurs. The current chapter describes the prin…

Dynamic in vivo Imaging of Microvasculature and Perfusion by Miniaturized Confocal Laser Microscopy

<i>Introduction:</i> Microvasculature and associated pathologies mandate dynamic imaging. We evaluated a novel miniaturized confocal laser scanning probe for in vivo visualization of blood vessels, blood flow, cell tracking and perfusion in both healthy rodents and disease models.<i> Methods:</i> The hand-held confocal microscopy system allowed a 500- to 2,400-fold magnification at a dynamically variable imaging depth. Different intravital stains were used alone or in combination for tissue, nuclear, plasma and vascular endothelial cell staining and for blood flow visualization, and targeted staining for individual cell populations. <i>Results:</i> Precis…

Die Leukozytenakkumulation in der Dünndarmwand nach Okklusion der A. mesent. sup. und Therapie des Reper-fusionsschocks mit Dopamin, isotonem und hyperton-hyperonkotischem Volumenersatz

Die Leukozyten sind ein wichtiger Faktor in der Entstehung des Reperfusionsschadens. Der Nachweis der Leukozytenakkumulation erfolgt experimentell durch die Messung der leukozytenspezifischen Myeloperoxidase-Aktivitat in der Mucosa des Darms oder durch die direkte Beurteilung des intravaskularen Leukozytenverhaltens mit der intravitalen Mikroskopie, die vorwiegend an den Mesenterialgefasen durchgefuhrt wird. Neuere Studien zeigten jedoch, das die Leukozytenakkumulation nicht in allen Darmwandschichten identisch ist [1, 4].

Detrimental Effects of 60 kHz Sonothrombolysis in Rats with Middle Cerebral Artery Occlusion

Recent studies have raised concerns about the safety of low frequency ultrasound in transcranial therapeutic application in cerebral ischemia. This study was designed to evaluate safety aspects and potential deleterious effects of low frequency, 60 kHz ultrasound in treatment of experimental middle cerebral artery occlusion (MCAO) in rats. Forty-five male Wistar rats were submitted to either temporary (90 min; groups I and II) or permanent MCAO (groups III and IV) using the suture technique. All animals received recombinant tissue plasminogen activator (rt-PA) starting 90 min after the beginning of occlusion. Groups I and III were additionally treated with 60 kHz ultrasound (time average ac…

Swelling and death of neuronal cells by lactic acid.

Lactacidosis occurring in cerebral ischemia or trauma is a major mechanism of cytotoxic brain edema and brain damage. Respective effects of lactacidosis were currently analyzed in vitro by employment of the murine neuronal cell line, Neuro-2A, in order to obtain a better understanding of specific mechanisms underlying cell swelling and cell death in comparison with glial cells. The cells were suspended in a physiological medium in the presence of lactic acid at increasing concentrations. Levels of acidosis reaching from pH 6.8-5.6 were obtained while other parameters, such as osmolarity and electrolyte concentrations, were maintained in the physiological range. Assessment of cell swelling a…

Electrophysiology and neuronal integrity following systemic arterial hypotension in a rat model of unilateral carotid artery occlusion.

Patients with carotid artery stenosis may be particularly susceptible to hypotension-associated cerebral ischemia and subsequent neurological sequelae. Measuring somatosensory evoked potentials (SEP), electroencephalogram (EEG), direct current (DC) potential, and histology, we compared the temporal evolution of cortical functional perturbations as well as neuronal integrity in a model of unilateral carotid artery occlusion and systemic hypobaric hypotension (HH) at the lower limit of cerebral blood flow autoregulation (50 mm Hg). Serial measurements of EEG power spectra as well as SEP-amplitudes and latencies of N10.3 were performed before, during, and up to 60 min after 30 min-HH (n=7) or …

Control of brain temperature during experimental global ischemia in rats.

Temperature control during experimental ischemia continues to be of major interest. However, if exposure of brain tissue is necessary during the experiment, regional heat loss may occur even when the core temperature is maintained. Furthermore, valid non-invasive brain temperature monitoring is difficult in small rodents. This paper describes a method for both monitoring and maintenance of brain temperature during small animal preparations in a stereotaxic frame. The device used includes an ear-bar thermocouple probe and a small near-infrared radiator. The new equipment permitted to maintain peri-ischemic brain temperature at a desired level while carrying out non-invasive continuous record…

Tolerance-Inducing Dose of 3-Nitropropionic Acid Modulates bcl-2 and bax Balance in the Rat Brain: A Potential Mechanism of Chemical Preconditioning

Many studies have reported ischemia protection using various preconditioning techniques, including single dose 3-nitropropionic acid (3-NPA), a mitochondrial toxin. However, the cellular signal transduction cascades resulting in ischemic tolerance and the mechanisms involved in neuronal survival in the tolerant state still remain unclear. The current study investigated the mRNA and protein expression of the antiapoptotic bcl-2 and the proapoptotic bax, two antagonistic members of the bcl-2 gene family, in response to a single dose of 3-NPA, to global cerebral ischemia–reperfusion, and to the combination of both 3-NPA-pretreatment and subsequent global cerebral ischemia–reperfusion. Brain h…

Effects of a single-dose hypertonic saline hydroxyethyl starch on cerebral blood flow, long-term outcome, neurogenesis, and neuronal survival after cardiac arrest and cardiopulmonary resuscitation in rats*

The beneficial effects of hypertonic saline on neuronal survival and on cerebral blood flow have been shown in several animal models of global and focal brain ischemia. Because of the potential benefits of hypertonic solutions, it is hypothesized that hydroxyethyl starch enhances cerebral blood flow and improves long-term outcome after cardiac arrest and cardiopulmonary resuscitation in an animal model.Laboratory animal study.University animal research laboratory.Fifty-nine male Sprague-Dawley rats.Rats were randomized to receive either 7.2% saline/6% hypertonic saline hydroxyethyl starch (4 mL/kg) or vehicle (NaCl 0.9 %) after 9 mins of asphyxic cardiac arrest and cardiopulmonary resuscita…

Systematic Analysis of Combined Thrombolysis Using Ultrasound and Different Fibrinolytic Drugs in an in Vitro Clot Model of Intracerebral Hemorrhage.

Adequate removal of blood clots by minimally invasive surgery seems to correlate with a better clinical outcome in patients with intracerebral hemorrhages (ICHs). Moreover, neurotoxic effects of recombinant tissue plasminogen activator have been reported. The aim of this study was to improve fibrinolysis using an intra-clot ultrasound application with tenecteplase and urokinase in our established ICH clot model. One hundred thirty clots were produced from 25 or 50 mL of human blood, incubated for different periods and equipped with drainage, through which an ultrasound catheter was placed in 65 treatment clots for 1 h, randomly allocated into three groups: administration of ultrasound, admi…

Transcranial Doppler and Cortical Microcirculation at Increased Intracranial Pressure and during the Cushing Response

The effect of increased intracranial pressure on the flow velocity of the basilar artery was measured with transcranial ultrasonic Doppler in New Zealand White rabbits under alpha-chloralose anesthesia and artificial respiration. Laser Doppler flowmetry served to study changes of the cortical microcirculation. The results confirm a high inverse correlation of the diastolic flow velocity, the pulsatility index, and the resistance index with the cerebral perfusion pressure (CPP). During acute intracranial hypertension, however, these parameters do not show a good correlation with the local cortical blood flow. The absence of a correlation was evident over a wide CPP range down to values of 35…

Mechanisms of arachidonic acid induced glial swelling

Accumulation of arachidonic acid (AA) in the brain during ischaemia may contribute to development of brain oedema. In this study we investigated the effect of selected drugs on AA-induced cytotoxic brain oedema in C6 glioma cells. Suspended C6 glioma cells were preincubated with drugs and AA (0.1 mM) was added. When no drug was administered cell volume increased immediately after the addition of AA with a maximum cell swelling of 13.1+/-1.9% at 15 min (mean +/- S.E. M.). Preincubation of cells with BW 755C, a dual inhibitor of cyclo- and lipoxygenases, showed no reduction in cell swelling from AA, whereas superoxide dismutase, amiloride and the protein kinase inhibitor H-9370 led to a signi…

Ultraschallkontrastmittel Levovist ® steigert den thrombolytischen Effekt von niederfrequentem Ultraschall

Hintergrund: Die therapeutische Anwendung von Ultraschall zur Rekanalisation eines akuten thrombotischen oder embolischen Gefasverschlusses stellt eine vielversprechende Alternative bzw. Erganzung existierender Therapieoptionen dar. Neuere Studien belegen eine thrombolytische Effizienz von Ultraschall in alleiniger Anwendung und in Kombination mit rr-PA. Ziel dieser Studie war es, zu untersuchen, ob sich durch Zugabe des Ultraschallkontrastmittels Levovist® eine Steigerung der ultraschallinduzierten Thrombolyse erreichen lasst.

Induction of Cerebral Ischemic Tolerance by Erythromycin Preconditioning Reprograms the Transcriptional Response to Ischemia and Suppresses Inflammation

Background A single dose of the macrolide antibiotic erythromycin can induce tolerance against cerebral ischemia in vivo (pharmacologic preconditioning). This study identified potential mechanisms of tolerance induction by assessing effects of erythromycin preconditioning on the cerebral transcriptional response to transient global cerebral ischemia. Methods Preconditioned and nonpreconditioned rats were exposed to 15 min of global cerebral ischemia, and changes in cerebral gene expression were identified by complementary DNA expression array and quantified by real-time reverse-transcription polymerase chain reaction. Results Ischemia caused a widespread up-regulation of transcription in n…

Accuracy and stability of temperature probes for intracranial application.

Intracranial temperature measurement may play a pivotal role for prognosis and treatment of neurological and neurosurgical patients. For reliable clinical application, accurate temperature readings are therefore necessary. We present an independent in vitro study investigating the accuracy and stability of three temperature probes. Eight Neurovent-P Temp (RN), eight Licox temperature sensors (LT) and eight Neurotrend sensors (NT) were placed into a water bath. The temperature was increased in 3 degrees C increments from 30 to 42 degrees C before (accuracy test day 0) and after (accuracy test day 5) a long-term stability test run at 37 +/- 0.2 degrees C. The accuracy tests revealed deviation…

Increased Hypoxic Tolerance by Chemical Inhibition of Oxidative Phosphorylation: “Chemical Preconditioning”

A short ischemic episode preceding sustained ischemia is known to increase tolerance against ischemic cell death. We report early-onset long-lasting neuroprotection against in vitro hypoxia by preceding selective chemical inhibition of oxidative phosphorylation: “chemical preconditioning.” The amplitude of CA1population spikes (psap) in hippocampal slices prepared from control animals (control slices) was 31 ± 27% (mean ± SD) upon 45-min recovery from 15-min in vitro hypoxia. In slices prepared from animals treated in vivo with 20 mg/kg 3-nitropropionate (3-np) 1–24 h prior to slice preparation (preconditioned slices), psap improved to 90 ± 15% (p < 0.01). Posthypoxic oxygen free radical…

Comparative analysis of in situ versus ex situ perfusion on micro circulation in liver procurement--an experimental trial in a porcine model.

The Achilles heel of liver transplantation remains the biliary system. The crucial step for liver preservation is effective rinsing and perfusion of the peribiliary plexus (PBP). Due to the physiology of the vascular tree, it seems almost impossible to achieve the necessary physiologic ranges of pressure and flow by the in situ perfusion technique. We investigated the role of additional ex situ perfusion via the hepatic artery in this animal model.Fifteen German Landrace pigs underwent standardized multiorgan procurement. In situ perfusion and additional ex situ perfusion were performed consecutively. Meanwhile the external pressure applied to the perfusion system was increased stepwise. To…

In vitro and in vivo porphyrin accumulation by C6 glioma cells after exposure to 5-aminolevulinic acid

Several malignant tissues synthesize endogenous porphyrins after exposure to 5-aminolevulinic acid (5-ALA). The present experiments have been designed to elucidate whether the C6 glioma cell, a model cell for human malignant glioma, similarly synthesizes porphyrins when exposed to 5-ALA, and whether specific synthesis occurs when C6 cells are inoculated into rat brains to form a tumor. In this situation the blood-brain barrier may interfere with 5-ALA availability, and spreading of porphyrins with edema outside the tumor may occur. Flow cytometry is used to determine the course of cell volume and porphyrin fluorescence intensities in cultured C6 cells which are incubated in 1 mM 5-ALA. For …

Cerebral embolic ischemia in rats: correlation of stroke severity and functional deficit as important outcome parameter.

The embolic MCA occlusion model in rats is used for recanalisation studies in acute stroke. In addition to the determination of lesion size, the assessment of functional outcome may improve the value of this model. Male Wistar rats were submitted to MCA clot embolism or sham surgery. In order to achieve a larger variety of lesion volume, 2 subgroups (each 7 animals) were subjected to differently sized emboli (30 and 40 mm). Follow-up period was 6 days. Outcome assessment consisted of a test battery including parallel bar crossing, observation of behaviour in an open field and an 8-arm maze and a neurological score with ten different sensorimotor and coordinative items. Animals were perfusio…

Biochemische Hirnprotektion

Mechanisms of endothelial cell swelling from lactacidosis studied in vitro

One of the early sequelae of ischemia is an increase of circulating lactic acid that occurs in response to anaerobic metabolism. The purpose of the present study was to investigate whether lactic acidosis can induce endothelial swelling in vitro under closely controlled extracellular conditions. Cell volume of suspended cultured bovine aortic endothelial cells was measured by use of an advanced Coulter technique employing the “pulse area analysis” signal-processing technique (CASY1). The isosmotic reduction of pH from 7.4 to 6.8 had no effect on cell volume. Lowering of pH to 6.6, 6.4, or 6.0, however, led to significant, pH-dependent increases of cell volume. Swelling was more pronounced …

Local Cerebral Blood Flow in a Rat Cortical Vein Occlusion Model

The symptoms following sinus and vein occlusion observed in patients and experimental animals display a considerable variability that so far remains largely unexplained. In a rat cortical vein occlusion model using a photochemical thrombotic technique, we examined changes in the cerebral venous flow pattern by fluorescence angiography and regional cerebral blood flow (rCBF) and cerebral blood volume fraction (CBVF) by a modern laser Doppler “scanning” technique. Brain damage was assessed histologically. Fluorescence angiographic findings fell into two groups: group A, rats with an altered venous flow pattern after occlusion (n = 12), and group B, rats with interruption of blood flow and/or…

Microcirculatory alterations in a mongolian gerbil sinus-vein thrombosis model

Summary Background and purpose. The pathophysiology of sinus-vein thrombosis (SVT) is still controversial in patients and experimental animals, the microcirculatory alterations in particular. This study was designed to develop a new sinus-vein thrombosis model and to further elucidate pathophysiological events such as the relationship between local and regional cerebral blood flow and haemoglobin oxygen saturation (HbSO2), changes of the microvasculature, leukocyte behaviour and brain tissue damage. Methods. In a first experimental series, animals were divided into two groups which resulted from different procedures of inducing SVT. In the SSS middle occlusion group (SMO group), SVT was ind…

Occurrence of Spontaneous Cortical Spreading Depression Is Increased by Blood Constituents and Impairs Neurological Recovery after Subdural Hematoma in Rats.

Acute subdural hemorrhage (ASDH) is common and associated with severe morbidity and mortality. To date, the role of spontaneous cortical spreading depression (sCSD) in exaggerating secondary injury after ASDH, is poorly understood. The present study contains two experimental groups: First, we investigated and characterized the occurrence of sCSD after subdural blood infusion (300 μL) via tissue impedance (IMP) measurement in a rat model. Second, we compared the occurrence and influence of sCSD on lesion growth and neurological deficit in the presence and absence of whole blood constituents. In the first experimental group, three IMP traits could be distinguished after ASDH: no sCSD, recurre…

Implantable Sensors Based on Gold Nanoparticles for Continuous Long-Term Concentration Monitoring in the Body.

Implantable sensors continuously transmit information on vital values or biomarker concentrations in bodily fluids, enabling physicians to survey disease progression and monitor therapeutic success. However, currently available technologies still face difficulties with long-term operation and transferability to different analytes. We show the potential of a generalizable platform based on gold nanoparticles embedded in a hydrogel for long-term implanted biosensing. Using optical imaging and an intelligent sensor/reference-design, we assess the tissue concentration of kanamycin in anesthetized rats by interrogating our implanted sensor noninvasively through the skin. Combining a tissue-integ…

Potent low dose platelet inhibitory effects of clopidogrel and aspirin on coronary thrombus formation in an animal model of acute unstable angina

SummaryApplication of clopidogrel before percutaneous coronary intervention in patients with acute coronary syndrome reduces the risk of cardiac events. Clopidogrel administration before surgery increases bleeding complications after CABG. Therefore, the antithrombotic effect of the low-dose combination of clopidogrel and aspirin was investigated in an in vivo pig model of coronary artery thrombus formation with cyclic flow reductions. The platelet inhibitory effect was determined by platelet aggregation and CFR, according to the methodology described by Folts. CFR were initiated by endothelial damage and placement of a constrictor around the LAD. 30 min after CFR were established, clopidog…

Application of C1-Esterase Inhibitor During Reperfusion of Ischemic Myocardium

Background—Complement activation during reperfusion of ischemic myocardium augments myocardial injury, and complement inhibition with C1-esterase inhibitor (C1-INH) at the time of reperfusion exerts marked cardioprotective effects in experimental studies. Application of C1-INH in newborns, however, was recently reported to have dangerous and even lethal side effects. This study addresses the essential role of dosage in studies using C1-INH.Methods and Results—Cardioprotection by C1-INH was examined in a pig model with 60 minutes of coronary occlusion followed by 120 minutes of reperfusion. C1-INH was administered intravenously 5 to 10 minutes before coronary reperfusion without heparin at a…

Glioblastoma-associated circulating monocytes and the release of epidermal growth factor.

✓ Monocytes/macrophages frequently infiltrate malignant gliomas and play a central role in the tumor-associated immune response as they process tumor antigen and present it to T-lymphocytes. Findings have accumulated that peripheral blood monocytes leaving the cerebral circulation become microglial cells and vice versa and that monocytes/macrophages may stimulate malignant tumor growth by some unknown mechanism. Most malignant gliomas express growth factor receptors, for example epidermal growth factor receptor (EGFR). The aim of this study was to determine whether peripheral blood monocytes of glioma patients release EGF, the appropriate ligand of gliomacell membrane-bound EGFR. Long-term …

A Scanning Technique to Measure Regional Cerebral Blood Flow and Oxyhemoglobin Level

OBJECTIVE: The application of a laser scanning technique to measure regional cerebral blood flow (CBF) and tissue hemoglobin oxygenation (HbO 2 ) using the rat closed cranial window preparation is described. METHODS: Twenty-nine male Wistar rats were used to consecutively measure local CBF by laser Doppler flowmetry and tissue HbO 2 by a microspectrophotometric method at multiple corresponding cortical locations. The scanning technique used a computer-controlled micromanipulator. Data from three experimental models are presented: the whisker stimulation model, the ischemia-reperfusion model, and the sinus-vein thrombosis model. Sequential changes in local CBF and HbO 2 data before, during, …

Effects of hypertonic/hyperoncotic treatment and surgical evacuation after acute subdural hematoma in rats*

Objective: The treatment of acute subdural hematoma (ASDH) consists mainly of surgical evacuation of the hematoma. It is conceivable that early preoperative neuroprotection with hypertonic/hyperoncotic treatment (HHT) can improve survival rates. The present study investigated the benefit of treatment with hypertonic/hyperoncotic solution on functional and histologic outcome as supportive therapy accompanying surgical intervention. Design: Laboratory experiment. Setting: University laboratory. Subjects: Male Sprague-Dawley rats weighing 296–350 g (n = 56). Interventions: ASDH was induced through subdural infusion of 400 μL of autologous venous blood. Thirty minutes after subdural blood infus…

Experimentelle Untersuchungen zum Einsatz verschiedener atrialer Dipolkonfigurationen für die Vorhof-Stimulation mit VDD-Elektroden

Fourier-Analyse der P-Welle bei der VDD-Stimulation. Ein intra-individueller Vergleich verschiedener atrialer Dipolkonfigurationen

Der Frequenzinhalt der wahrgenommenen P-Welle wird bei der VDD-Stimulation sowohl von der Dipollokalisation, als auch von der Dipolkonfiguration beeinflust. Eine Vergroserung der Dipoloberflache resultiert in der Detektion tieferer Frequenzen.

Neuroprotection of S(+) ketamine isomer in global forebrain ischemia

The non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine can block the action of excitotoxic amino acids in the central nervous system. S(+) ketamine has a 2-3 times higher anesthetic potency compared with the ketamine-racemate and also shows a higher neuroprotective efficacy in vitro. To determine the neuroprotective activity of S(+) ketamine compared with its R(-) stereoisomer in vivo, we examined the functional and neurohistological outcome in rats treated 15 min after global forebrain ischemia with S(+) ketamine in different dosages compared with R(-) ketamine. Influence of the treatment on regional cerebral blood flow (rCBF) and cortical oxygen saturation (HbO2) was…

Surgical research and clinical routine in the new century.

The German Research Foundation (DFG) has recentlydenounced the poor state of clinical research in Germany[2]. It is therefore worthwhile to contemplate the currentstate of surgical research with special focus on the futurepossibilities to combine research and clinical routine inuniversity hospitals.Current StateReading the daily newspaper one may get the impres-sion that German universities and clinical research in par-ticular are in a deep crisis, and that German professors areto be blamed for it. In medicine, additional insufficienciesof the system are obvious, with corruption cases broughtup against clinicians and conflicts of interest due to thefact that clinical professors in addition …

In-vitro Untersuchungen zu photodynamisch induzierten Dosis-Wirkungs-Beziehungen

Im Gegensatz zu fruheren Annahmen wurde von Rodgers 1990 in Frage gestellt, das aus der Quantifizierung der Fluoreszenz im Gewebe Aussagen uber die Konzentration des Photosensibilisators noch uber die zu erwartenden photodynami-schen Effekte moglich sind (1).

EndothelinA receptor antagonist BSF-208075 causes immune modulation and neuroprotection after stroke in gerbils.

Leukocytes contribute to the ischemia-reperfusion injury. Recent studies suggested endothelins could be important mediators for leukocyte activation in stroke. We tested if the endothelinA receptor antagonist BSF-208075 (ambrisentan) could reduce an ischemic lesion by modulation of leukocyte-endothelium interactions. Twenty-four gerbils underwent either a sham operation (n=6) or 15 min of bilateral carotid artery occlusion resulting in global cerebral ischemia. Ischemic animals received normal saline (n=6), 5 mg/kg BSF-208075 (n=6) or 30 mg/kg (n=6) administered intravenously at 10 min of reperfusion. Leukocytes rolling or adhering to endothelium were counted by intravital microscopy in par…

C1-ESTERASE INHIBITOR REVERSES FUNCTIONAL CONSEQUENCES OF SUPERIOR MESENTERIC ARTERY ISCHEMIA/REPERFUSION BY LIMITING REPERFUSION INJURY AND RESTORING MICROCIRCULATORY PERFUSION

Activated complement contributes significantly to reperfusion injury after ischemia. This study explores functional consequences of C1-esterase inhibitor (C1-INH) treatment after superior mesenteric artery occlusion (SMAO)/ reperfusion using intravital microscopy. Thirty anesthetized, spontaneously breathing, male Sprague-Dawley rats underwent SMAO for 60 min followed by reperfusion (4 h). C1-esterase inhibitor (100 and 200 IU/kg body weight) or saline (0.9%) was given as a single bolus before reperfusion. Sham-operated animals (n = 10) without SMAO served as controls.Systemichemodynamicsweremonitoredcontinuously,arterial bloodgasesanalyzedintermittently, andleukocyte/ endothelial interacti…

Genomic response of the rat brain to global ischemia and reperfusion

To identify genes that are involved in ischemia response of the brain, we have evaluated changes of gene expression in rat cerebrum after 15 min complete global ischemia, followed by reperfusion for 1 h, 6 h or 24 h. The expression profiles of approximately 30,000 transcripts from three subjects in each group (including sham-operated controls) were monitored employing oligonucleotide microarrays. About 20,000 transcripts were detectable in rat brains. The levels of 576 transcripts (approximately 2.9%) were significantly altered in response to experimental ischemia. 419 transcripts were up- and 157 downregulated; 39 transcripts changed after 1 h reperfusion, 174 after 6 h and 462 after 24 h.…

Glial ion transport and volume control.

K(+)-induced glial swelling results from an intricate interaction of transport and diffusion processes and metabolic stimulation, with many open questions remaining. Our concept of the major mechanisms involved can be summarized as follows: high extracellular K+ causes a burst-like stimulation of Na+/K+ ATPase and, hence, increases the metabolic demands. Lactate is produced; the cell is slightly acidified. To maintain a normal intracellular pH, the Na+/K+ antiporter extrudes protons and supplies Na+ for further Na+/K+ exchange. In addition, K+ ions enter the cell via membrane channels or furosemide-inhibitable transport. K+, Cl-, and lactate- ions accumulate as the osmotic basis for cell sw…