Search results for " blood flow"

2013

Neurovascular coupling (NVC) in the adult central nervous system (CNS) is a mechanism that provides regions of the brain with more oxygen and glucose upon increased levels of neural activation. Hemodynamic changes that go along with neural activation evoke a blood oxygen level-dependent (BOLD) signal in functional magnetic resonance imaging (fMRI) that can be used to study brain activity non-invasively. A correct correlation of the BOLD signal to neural activity is pivotal to understand this signal in neuronal development, health and disease. However, the function of NVC during development is largely unknown. The rodent whisker-to-barrel cortex is an experimentally well established model to…

Control of brain temperature during experimental global ischemia in rats.

1999

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…

Interrelationship between mean arterial blood pressure, blood flow, and vascular resistance in solid tumor tissue of DS-carcinosarcoma

1975

In vivo-Untersuchungen der Tumordurchblutung an Implantationstumoren eines DS-Carcinosarkoms in der Rattenniere zeigen eine deutliche Abhangigkeit der Durchblutungsgrosse vom Tumorgewicht. Bei Variation des arteriellen Mitteldrucks zwischen 40 und 135 mm Hg steigt die Durchblutung der einzelnen Tumoren linear mit zunehmendem Perfusionsdruck an. Eine zunehmende Rarefizierung der terminalen Strombahn mit ansteigendem Tumorgewicht wird belegt durch eine starke Zunahme des Stromungswiderstandes, der schon bei sehr jungen Tumoren wesentlich hohere Werte als bei verschiedenen Organen aufweist.

Cerebral Oxygen Supply in Brain Edema and During Ventriculo-Cisternal Perfusion

1976

Numerous brain injuries and brain tumors lead to edema in brain tissue which can have consequences for the oxygen supply to the damaged tissue as well as to adjacent tissue areas. In studies made of the blood flow and oxygen supply in perifocal edematous tissue of brain tumors and lesions in patients undergoing various brain operations a direct relationship between the regional blood flow and the water content could be demonstrated (3). As the water content of the tissue increased, the blood flow through it diminished. In many cases, the reduction of the blood flow in the brain tissue induced an insufficient oxygen supply. In the tissue samples under investigation, the CrP and ATP concentra…

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

1996

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 …

Lost in Transition: A Systematic Review of Neonatal Electroencephalography in the Delivery Room—Are We Forgetting an Important Biomarker for Newborn …

2017

Background: Electroencephalography (EEG) monitoring is routine in neonatal intensive care units (NICU) for detection of seizures, neurological monitoring of infants following perinatal asphyxia, and increasingly, following preterm delivery. EEG monitoring is not routinely commenced in the delivery room (DR). Objectives: To determine the feasibility of recording neonatal EEG in the DR, and to assess its usefulness as a marker of neurological wellbeing during immediate newborn transition. Methods: We performed a systematic stepwise search of PubMed using the following terms: infant, newborns, neonate, delivery room, afterbirth, transition and electroencephalography. Only human studies describ…

Intravascular pillars and pruning in the extraembryonic vessels of chick embryos.

2010

To investigate the local mechanical forces associated with intravascular pillars and vessel pruning, we studied the conducting vessels in the extraembryonic circulation of the chick embryo. During the development days 13-17, intravascular pillars and blood flow parameters were identified using fluorescent vascular tracers and digital time-series video reconstructions. The geometry of selected vessels was confirmed by corrosion casting and scanning electron microscopy. Computational simulations of pruning vessels suggested that serial pillars form along pre-existing velocity streamlines; blood pressure demonstrated no obvious spatial relationship with the intravascular pillars. Modeling a Re…

Regional distribution of blood flow in the renal cortex

1969

Es wird ein autoradiographisches Verfahren zur Bestimmung der regionalen Durchblutungsverteilung in differenziert strukturierten Organen beschrieben. Mit dieser neuen Methode wird die Durchblutung der Nierenrinde untersucht. Es wird nachgewiesen, dass die Durchblutungs- bzw. Widerstandsverteilung innerhalb der Rinde nicht einheitlich ist, sondern dass sich drei verschieden durchblutete, anatomisch voneinander abgrenzbare Teile unterscheiden lassen.

Small-volume hypertonic saline solution and high-dosage furosemide in the treatment of refractory congestive heart failure. A pilot study

2000

Objective: To evaluate a new therapeutic approach to hospitalised patients with refractory congestive heart failure (CHF) based on published data on the efficacy of furosemide (frusemide) intravenous infusion in refractory CHF and of small volumes of hypertonic saline solution in the low-flow state. Design and Setting: Prospective, uncontrolled study of hospital inpatients. Study Participants and Interventions: Thirty patients (20 males and 10 females) aged 65 to 85 years with refractory New York Heart Association (NYHA) functional class IV CHF were given a twice-daily intravenous infusion of a small volume of hypertonic saline solution (150 ml of 1.4 to 4.6 NaCl) containing high-dosage fur…

Autoradiographic technique to assess distribution of blood flow within organs

1969

A method is described for assessing the distribution of blood flow within organs. Microspheres, 5–50 μ in diameter, labelled with a beta-emitting isotope were injected into the left ventricle of experimental animals. The distribution of the indicator within the tissues, which is assumed to represent the regional distribution of flow, was visualized and measured quantitatively by autoradiography. Local flow rates in areas of about 1,2 mm in diameter could be determined. Application of the technique for the study of regional myocardial and renal circulation is demonstrated.