0000000000022987
AUTHOR
Juan A. Barcia
Quantification of intracranial contribution to rheoencephalography by a numerical model of the head
Abstract Objectives : Partial contributions of intracranial and extracranial circulation to rheoencephalography (REG) remain uncertain. The main goal of this work is to determine theoretically the capability of REG techniques to reflect intracranial blood flow. Methods : Head and current injection electrodes were computationally modeled to assess REG sensitivity to brain and scalp conductivity changes. Data obtained were related to tissue perfusions to calculate the partial contribution of cerebral blood perfusion to REG I, REG II and monopolar REG and to assess their amplitudes. Results : When REG I and monopolar REG were used, the theoretical maximum of intracranial contribution was reach…
Prophylactic Percutaneous Sealing of Lumbar Postdural Puncture Hole with Fibrin Glue to Prevent Cerebrospinal Fluid Leakage in Swine
UNLABELLED We explored the effect of fibrin glue injection at the site of dural puncture on cerebrospinal fluid (CSF) leakage in a swine model. Pigs were subjected to a lumbar dural CSF puncture in the sitting position with a 17-gauge Tuohy needle. Fibrin glue 1.4 mL was injected through the same needle into the epidural space. Evans blue dye was infused through the cisterna magna 15 min later, and the appearance of dyed CSF through the skin puncture and along the needle trajectory to the dura was inspected and categorized. In seven of eight animals, the CSF leak was sealed with fibrin glue. Control animals were injected with 1.4 mL saline. A sham operation group of animals underwent cister…
Suppression of the cardiac electric field artifact from the heart action evoked potential
The study of heart action-related brain potentials is strongly disrupted by the presence of an inherent cardiac electric artifact. The hypothesis is presented that most of the electric current coupled to the cardiac field surrounds the skull and flows through the scalp tissue without crossing the cranial cavity. This pseudo two-dimensional conduction model contrasts with the volumetric conduction of the brain electrical activity, and this property is exploited to cancel the cardiac electric artifact. QRS loop vector-cardiographic projections on saggital planes were recorded in 11 healthy subjects in the head and neck areas. Comparative analysis of the projection eccentricities, estimated by…
Coexpresión de NG2/GFAP tras la diferenciación en células transfectadas con las mutaciones de GFAP y en células procedentes de gliomas indiferenciados
Resumen: Introducción: La enfermedad de Alexander es una enfermedad rara causada por mutaciones en el gen que codifica la proteína glial ácida fibrilar (GFAP). En un estudio previo hemos observado que la diferenciación de neuroesferas transfectadas con estas mutaciones genera un tipo celular que comparte la expresión de GFAP y NG2. Objetivos: Determinar el efecto de las mutaciones en marcadores moleculares en comparación con células de glioma diferenciados que expresan simultáneamente GFAP y NG2. Métodos: Se utilizaron muestras de glioblastoma humana (GLM) y neuroesferas procedentes de rata transfectadas con mutaciones de GFAP para el análisis de la expresión tras diferenciación de GFAP y N…
The hippocampal dentate gyrus is essential for generating contextual memories of fear and drug-induced reward
The hippocampus is believed to play a role in processing information relative to the context in which emotionally salient experiences occur but evidence on the specific contribution of the hippocampal dentate gyrus (DG) to these processes is limited. Here, we have used two classical behavioral paradigms to study the participation of the dorsal DG in context-conditioned reward and context-conditioned fear. Rats received intra-hippocampal vehicle or colchicine injections (4 μg/μl solution; 0.2 μl injections at 10 sites) that damaged the DG but spared other hippocampal subfields. In the first experiment, we used a place conditioning procedure pairing cocaine exposure (20 mg/kg, i.p.) with a sp…
Combined thoracotomy and laminectomy for spinal cavernomas with intrathoracic growth.
Dumbbell shaped epidural cavernomas are uncommon lesions. Of these, the extraforaminal extension is usually limited, and the lesions are removed surgically by an extended laminectomy. We present two cases of dumbbell shaped epidural cavernomas with a considerable intrathoracic growth. They were resected through a combined thoracotomy and laminectomy. Only in the case in which a wide approach to the posterior mediastinum was performed it was possible to completely remove the lesion. Since it is possible to anticipate this histological diagnosis by the magnetic resonance imaging characteristics, we propose that a wide transthoracic approach should be performed associated to a laminectomy if a…
Influence of the scalp thickness on the intracranial contribution to rheoencephalography
In spite of the great efforts made by the scientific community, up to now there is no agreement about the rheoencephalography (REG) capability to reflect cerebral blood flow (CBF). Moreover, a standard procedure and the optimal electrode arrangement have not been established yet. In a previous study, we found, using a classical four-shell spherical model of the head and solving it by numerical methods that, theoretically, there could exist an electrode arrangement to register an REG II free of extracranial contribution. In this paper, we have studied the influence of scalp thickness on the intracranial contribution to REG II. The study has been performed by solving the head model, using in …
Radiosurgical Treatment of low flow Carotid-Cavernous Fistulae
The good results obtained by stereotactic radiosurgery in arteriovenous malformations has led the authors to expect similar results in low flow carotid-cavernous fistulae. In this paper, 20 cases who underwent radiosurgery with a conventional gamma source are presented. The total dose delivered was 36 to 40 Gy. 90% of the patients were cured after radiosurgery after a mean time of 7 months. Those presenting a mild improvement after a mean time of 2 months and those with a marked improvement after 4 months.
Binge administration of 3,4-methylenedioxymethamphetamine ("ecstasy") impairs the survival of neural precursors in adult rat dentate gyrus.
3,4-Methylenedioxymethamphetamine (MDMA) is a potent stimulant and hallucinogenic drug whose ability to regulate neurogenesis in the adult has not been previously investigated. We used 5'-bromo-2-deoxyuridine (BrdU) and Ki-67 as mitotic markers, and doublecortin (DCX) as a marker of immature neurons, to study proliferation, survival and maturation of adult-generated cells in the dentate gyrus (DG) of the hippocampus following binge administration of MDMA (8 injections of 5 mg/kg at 6 h intervals). The results showed that MDMA treatment did not affect cytogenesis in the DG, but significantly decreased the survival rate of cells incorporated after 2 weeks to the granular layer of the DG by ca…
Chronic cocaine exposure impairs progenitor proliferation but spares survival and maturation of neural precursors in adult rat dentate gyrus
Recent observations indicate that drugs of abuse, including alcohol and opiates, impair adult neurogenesis in the hippocampus. We have studied in rats the impact of cocaine treatment (20 mg/kg, daily, i.p.) on cell proliferation, survival and maturation following short-term (8-day) and long-term (24-day) exposure. Using 5'-bromo-2-deoxyuridine (BrdU) and Ki-67 as mitotic markers at the end of the drug treatments, we found that both short- and long-term cocaine exposures significantly reduced cell proliferation in the dentate gyrus (DG) of the hippocampus. By labelling mitotic cells with BrdU pulses before or during the early stages of the drug treatment, we determined that long-term cocaine…
Stereotactic Radiosurgery of Deeply Seated Low Grade Gliomas
The authors report the results of a series of 16 cases of low-grade gliomas in whom radiosurgery was performed. This series started in 1977. All the tumours received a single radiosurgical session (with a mean dose of 21.7 Gy, 5–10mm. collimator; one patient received two sessions and in another patient two different targets were irradiated in the same session). Prior to radiosurgery, six patients received conventional external fractionated radiotherapy, with two lateral fields of up to 10 × 10 cm. and a mean dose of 55.1 Gy. and another six patients with tumours less than 5 cm. in diameter, received stereotactic radiotherapy using four fields of up to 5 × 5 cm. and a mean dose of 53.1 Gy. I…
Meningiomas del agujero magno y primeros segmentos cervicales
Resumen Se presentan 6 pacientes con meningiomas situados en el agujero magno recogidos durante los dos ultimos anos. La clinica inicial que presentaban fue totalmente inespecifica simulando la mayoriade ellos un cuadro de espondilosis cervical. El diagnostico morfologico de la lesion se baso en la TC y RM de fosa posterior y primeros segmentos cervicales. Con estas pruebas se confirmo la presencia de una masa tumoral, de caracter intradural y de contornos bien definidos, con presentacion lateral en 4 casos y anterior en 2. En todos los casos se procedio de forma precoz a la reseccion total de la masa tumoral intradural por via posterior a traves de una craniectomia suboccipital y laminecto…
Survival and differentiation of embryonic neural explants on different biomaterials
Biomaterials prepared from polyacrylamide, ethyl acrylate (EA), and hydroxyethyl acrylate (HEA) in various blend ratios, methyl acrylate and chitosan, were tested in vitro as culture substrates and compared for their ability to be colonized by the cells migrating from embryonic brain explants. Neural explants were isolated from proliferative areas of the medial ganglionic eminence and the cortical ventricular zone of embryonic rat brains and cultured in vitro on the different biomaterials. Chitosan, poly(methyl acrylate), and the 50% wt copolymer of EA and HEA were the most suitable substrates to promote cell attachment and differentiation of the neural cells among those tested. Immunofluor…
[Transphenoidal endoscopic approaches for pituitary adenomas: a critical review of our experience].
Abstract Background The surgical approach to the pituitary fossae has evolved from transcranial to sublabial and transseptal microscopic ones, up to the current transsphenoidal endoscopic approach. Objectives To present our experience in the transnasal transsphenoidal approach for pituitary adenomas and the modifications introduced to improve tumoral resection and to lower iatrogenia. Material and methods Over nine years, we operated on 37 patients with pituitary adenomas using the transsphenoidal endoscopic approach. We utilised optical lens of 0° (approach) and 30° (adenoma resection), optic navigator, surgical instruments for nasal endoscopic and pituitary surgery. During the neurosurgic…
Stereotactic Radiotherapy plus Radiosurgical Boost in the Treatment of Large Cerebral Arteriovenous Malformations
Small sized AVMs respond well to stereotactic radiosurgery, while larger AVMs do poorly with stereotactic radiosurgery or stereotactic fractionated radiotherapy. A combination of both methods is proposed for the treatment of these larger lesions.
Improved technique for stereotactic placement of nerve grafts between two locations inside the rat brain
Peripheral nerve grafts have shown the ability to facilitate central axonal growth and regenerate the adult central nervous system. However, the detailed description of a technique for atraumatic graft placement within the brain is lacking. We present a stereotactic procedure to implant a peripheral nerve graft within a rat's brain with minimal brain tissue damage. The procedure permits a correct graft placement joining two chosen points, and the survival and integration of the graft in the host tissue with a light glial reaction, with evidence of central axonal growth inside the graft, at least up to 8 weeks after its implantation. (C) 2008 Elsevier B.V. All rights reserved.
Continuous intra-amygdalar infusion of GABA in the amygdala kindling model of epilepsy in rat.
Objective: To explore the effect of continuous intra-amygdalar infusion of GABA in the amygdala kindling model of epilepsy in rat. Methods: An electrode and cannula complex was implanted in adult male Wistar rats, the electrode being targeted to the left basolateral amygdala. The animals were subjected to a standard kindling procedure. Osmotic minipumps filled with either GABA or mannitol were connected to cannulas and allowed to infuse during 7 days. Kindling experiments measuring after-discharge and seizure thresholds, seizure severity and duration, and behavioral toxicity were performed before, during and after the drug infusion period. Results: Both after-discharge and seizure threshold…
Abordajes transesfenoidales endoscópicos de los adenomas hipofisarios: una revisión crítica de nuestra experiencia
Resumen Introduccion El abordaje quirurgico de la region hipofisaria ha evolucionado desde las vias transcraneales, a las sublabiales y transseptales microscopicas hasta los abordajes endoscopicos actuales. Objetivos El objetivo de este trabajo es exponer y reflexionar sobre nuestra experiencia en el abordaje transnasal transesfenoidal endoscopico de los tumores hipofisarios, con las modificaciones que hemos introducido para mejorar la exeresis del tumor y disminuir la iatrogenia. Material y metodos A lo largo de 9 anos hemos intervenido a 37 pacientes afectos de adenomas hipofisarios mediante abordaje transesfenoidal endoscopico. Utilizamos lentes de 0 y 30 grados, navegador optico, instru…
Human Mesenchymal Stem Cells Prevent Neurological Complications of Radiotherapy
Radiotherapy is a highly effective tool for the treatment of brain cancer. However, radiation also causes detrimental effects in the healthy tissue, leading to neurocognitive sequelae that compromise the quality of life of brain cancer patients. Despite the recognition of this serious complication, no satisfactory solutions exist at present. Here we investigated the effects of intranasal administration of human mesenchymal stem cells (hMSCs) as a neuroprotective strategy for cranial radiation in mice. Our results demonstrated that intranasally delivered hMSCs promote radiation-induced brain injury repair, improving neurological function. This intervention confers protection against inflamma…
Inhibition of adult hippocampal neurogenesis disrupts contextual learning but spares spatial working memory, long-term conditional rule retention and spatial reversal.
Neurogenesis in the adult dentate gyrus (DG) of the hippocampus has been implicated in neural plasticity and cognition but the specific functions contributed by adult-born neurons remain controversial. Here, we have explored the relationship between adult hippocampal neurogenesis and memory function using tasks which specifically require the participation of the DG. In two separate experiments several groups of rats were exposed to fractionated ionizing radiation (two sessions of 7 Gy each on consecutive days) applied either to the whole brain or focally, aiming at a region overlying the hippocampus. The immunocytochemical assays showed that the radiation significantly reduced the expressio…
Radiosurgery of Epilepsy
Since 1982 a series of 11 epileptic patients have been treated with stereotactic radiosurgery. Patients were intracranially recorded with cortical and deep electrodes until the location of the epileptogenic focus was determined. A deep electrode was stereotactically placed at this point to confirm the accuracy of the location. All patients received radiosurgery with a gamma source and a dose of 10 to 20 Gy, except two of them in which a betatron was used. The results were: Total disappearance of the crises and withdrawal of medication: 4 cases (36%). More than 80% reduction of crises: 3 cases (27%). More than 50% reduction of crises: 2 cases (18%). Less than 50% reduction of crises: 2 cases…
Spared place and object-place learning but limited spatial working memory capacity in rats with selective lesions of the dentate gyrus
We studied the cognitive performance of rats with colchicine-induced lesions of the hippocampal dentate gyrus (DG) on a range of spatial, non-spatial and mixed spatial/procedural tasks. Rats were assigned to three experimental groups receiving large colchicine lesions (7 μg per hippocampus), small colchicine lesions (1.75 μg per hippocampus) or sham lesions. Stereological estimates of cell density indicated that the colchicine treatments induced dose-dependent damage to the DG, while sparing in large part other hippocampal subfields. Remarkably, the behavioural results showed that the colchicine lesions did not affect the performance of rats in an object discrimination task, in an object-pl…
NG2 and GFAP co-expression after differentiation in cells transfected with mutant GFAP and in undifferentiated glioma cells
Introduction: Alexander disease is a rare disorder caused by mutations in the gene coding for glial fibrillary acidic protein (GFAP). In a previous study, differentiation of neurospheres transfected with these mutations resulted in a cell type that expresses both GFAP and NG2. Objective: To determine the effect of molecular marker mutations in comparison to undifferentiated glioma cells simultaneously expressing GFAP and NG2. Methods: We used samples of human glioblastoma (GBM) and rat neurospheres transfected with GFAP mutations to analyse GFAP and NG2 expression after differentiation. We also performed an immunocytochemical analysis of neuronal differentiation for both cell types and dete…
Subventricular zone in motor neuron disease with frontotemporal dementia.
Investigate how the subventricular proliferation and organisation is modified in a patient with FTLD-ALS. We studied the subventricular zone (SVZ) of a patient with FTLD-ALS immunohistochemical and histologically. We found an increase of Ki-67 positive cells and neuroblast in the subventricular zone, suggesting an activation of proliferating activity in response to FTD-ALS. This proliferation can act as a compensatory mechanism for rapid neuronal death and its modulation could provide a new therapeutic pathway in ALS. These results suggest a modification of neurogenesis in FTD-ALS. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
Radiosurgery of Carotid-Cavernous Fistulae
25 cases of carotid-cavernous fistulae (CCF) who underwent radiosurgery with a conventional gamma source from 1977 to 1992 are reported. 22 were low-flow, spontaneous CCFs and 3 were high flow fistulae which had undergone a previous trApplng. The total dose delivered was 30 to 40 Gy. 91% to patients with low-flow CCF cured after radiosurgery in a mean time of 7.5 months, presenting improvent in a mean time of 2.3 months. Only one of the high-flow fistulae was cured. Follow-up period ranged between 14 years and 15 months (mean: 50 months). No recurrence was recorded in any case. While intravascular embolotherapy is the treatment of choice for high-flow fistulae, stereotactic radiosurgery may…