Biomedical subjects

K Dorovini-Zis

Publications and source records attributed to K Dorovini-Zis.

At least 37 records · Page 2Linked to original sources

PubMed1994

Hippocampal synaptic pathology in patients with temporal lobe epilepsy.

Immunostaining of synaptic terminals was studied in the hippocampus of 26 patients who had surgical resections for intractable temporal lobe epilepsy. Two monoclonal antibodies (EP10 and SP12) reactive with distinct synaptic antigens were used on paraffin-embedded tissues. The results indicated qualitative reductions on synaptic terminals in CA4 and other regions where cell loss is reported. The inner molecular layer of the dentate gyrus was observed to have increased synaptic immunostaining. Synaptic terminal loss in CA4 and redistribution in the molecular layer were most frequent in cases with hippocampal sclerosis. However, both forms of synaptic pathology were also noted in most cases where the pathological findings were classified as indefinite, and in some cases associated with mass lesions of the temporal lobe. These results support the importance of neuronal loss and synaptic reorganization as possible mechanisms of illness in epilepsy. They also indicate that synaptic immunostaining may be a useful adjunct to routine neuropathological diagnostic techniques.

Adolescent↗

PubMed1994

Additive effect of allopurinol and deferoxamine in the prevention of spinal cord injury caused by aortic crossclamping.

Fourteen domestic swine were divided into two groups. Group A (n = 7) was the control group, in which no pharmacologic intervention was applied. In group B (n = 7), the ischemic-reperfused spinal cord was treated with the combination of allopurinol (50 mg/kg/day for 3 days before the day of operation) and deferoxamine (Desferal, 50 mg/kg administered intravenously over 3 to 4 hours). The administration of deferoxamine was completed 1 hour before crossclamping. The crossclamp was placed on the descending aorta just distal to the left subclavian artery for 30 minutes. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. Methods of assessment included an evaluation of the neurologic status of the animals by quantitative Tarlov criteria, blood flow by radiolabeled microspheres, and histologic examination of the spinal cord. All animals in the control group, group A, were completely paraplegic with 0% recovery by Tarlov criteria at 24 hours after the removal of the crossclamp. In contrast, all animals in group B, in which the combination of allopurinol and deferoxamine was used, completely recovered (100% recovery by Tarlov criteria), and at 24 hours after the ischemic episode they were able to walk with no difficulty and had intact sensation. Functional parameters of these animals fully correlated with the morphologic findings. Widespread acute neuronal injury and vacuolation of neuropil were observed in the control group of animals. In contrast, animals in group B showed much less pronounced morphologic changes after the same period of ischemia. In summary, the combined use of these agents significantly (p < 0.001) reduced the incidence of paraplegia induced by aortic crossclamping with 82% additivity.

Allopurinol↗

PubMed1993

Effects of interferon-gamma on primary cultures of human brain microvessel endothelial cells.

Primary cultures of human brain microvessel endothelial cells were used to study the effects of human recombinant interferon-gamma (IFN-gamma) on cerebral endothelium in vitro. Incubation of monolayers with various concentrations of IFN-gamma (10 to 200 U/ml) for 12 to 96 hours induced surface expression of class II major histocompatibility complex (Ia) antigen in a time- and concentration-dependent manner. In immunogold-stained cultures, labeling was observed as early as 12 hours, was maximal after 48 hours, and persisted at plateau levels in the continuous presence of the cytokine. Expression was blocked by coincubation with anti-IFN-gamma antibody and was reversed 4 days following removal of IFN-gamma from the culture media. Endothelial cells treated with IFN-gamma for 3 to 4 days became spindle-shaped, extensively overlapped, and frequently formed cellular whorls. These changes did not occur in the presence of anti-IFN-gamma antibody and reversed upon removal of IFN-gamma from the media. The morphological alterations were associated with increased permeability of confluent monolayers to macromolecules as compared with untreated cultures. The results of these studies indicate that human brain microvessel endothelial cells respond to in vitro cytokine stimulation by undergoing profound morphological, functional, and permeability changes. We conclude that cerebral endothelium may play an important role in the initiation and regulation of lymphocyte traffic across the blood-brain barrier in inflammatory disorders of the human central nervous system.

Capillary Permeability↗

PubMed1992

Upregulation of intercellular adhesion molecule-1 (ICAM-1) expression in primary cultures of human brain microvessel endothelial cells by cytokines and lipopolysaccharide.

The expression of intercellular adhesion molecule-1 (ICAM-1) by human cerebral endothelium was studied in primary cultures of human brain microvessel endothelial cells following treatment with bacterial lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma). Surface expression of ICAM-1 was examined with the immunogold silver staining technique. Intact cerebral endothelial cells constitutively express low levels of ICAM-1. Stimulation with LPS and cytokines induces upregulation of ICAM-1 which is minimal with IFN-gamma and maximal with LPS or a combination of IFN-gamma and TNF-alpha. Upregulation of ICAM-1 expression is concentration- and time-dependent, is observed as early as 4 h following incubation and persists for up to 72 h in the continuous presence of LPS or cytokines. The ICAM-1 expression is not reversed by 3 days after removal of the LPS or cytokines. These findings may be relevant to the interactions between leukocytes and brain microvessel endothelial cells in inflammatory and demyelinating diseases of the CNS.

Brain↗

PubMed1992

Haemophilus influenzae lipopolysaccharide disrupts confluent monolayers of bovine brain endothelial cells via a serum-dependent cytotoxic pathway.

An in vitro blood-brain barrier (BBB) model consisting of primary cultures of bovine brain microvascular endothelial cells was used to examine the effect of Haemophilus influenzae type b (Hib) on the BBB. Whole bacteria and purified lipopolysaccharide (LPS; greater than 10 ng/ml) caused marked cytotoxicity on the bovine brain endothelial cells. This effect could be completely blocked by polymyxin B. Similar cytotoxic effects were observed with a cultured bovine pulmonary endothelial cell line. Serum was essential for the LPS-mediated cytotoxic effect, and human, horse, bovine, or fetal calf serum all had similar effects. The serum factor was not a complement component. A monoclonal antibody against CD14, a receptor involved in mediating the effect of LPS in monocytes, completely blocked the cytotoxic effect in both brain and pulmonary endothelial cells. These results suggest that Hib LPS disrupts an in vitro BBB model via a serum- and CD14-dependent pathway and that LPS has cytotoxic effects on bovine endothelial cells without the involvement of monocytic cells, an effect that may be important in gram-negative meningitis and in endotoxic shock.

Animals↗

PubMed1992

Adhesion and migration of human polymorphonuclear leukocytes across cultured bovine brain microvessel endothelial cells.

Adhesion and migration of human polymorphonuclear leukocytes (PMN) across cerebral endothelium were studied in an in vitro model consisting of monolayers of bovine brain microvessel endothelial cells (BBMEC) grown on amniotic stroma or collagen membranes. Polymorphonuclear leukocytes were stimulated to adhere to and migrate across confluent BBMEC monolayers in response to chemotactic gradients produced by formyl-methionyl-leucyl phenylalanine (fMLP), leukotriene B4 (LTB4) or acetyl-glyceryl-ether-phosphorylcholine (AGEPC) placed below the cultures. Under these conditions, PMN adherence to endothelium was 2-10-fold greater than that observed in the absence of chemoattractants or in the presence of equal concentrations of chemoattractants below and above the cultures. Transendothelial migration of PMN occurred rapidly and at focal points across the monolayers. Scanning and electron microscopic studies revealed that stimulated PMN migrated across the monolayers by first adhering to the apical surface of the endothelium and then moving between adjacent endothelial cells. Following their migration, PMN accumulated beneath the endothelium. The overlying endothelial monolayers showed no evidence of disruption and the interendothelial junctions appeared intact at the end of the migration period. We conclude that this in vitro system reproduces the endothelial cell-leukocyte interactions occurring during acute inflammation in vivo and should provide a useful in vitro model for studying the molecular mechanisms underlying these interactions in inflammatory diseases of the central nervous system.

Animals↗

PubMed1992

Ultrastructural localization of factor VIII-related antigen in cultured human brain microvessel endothelial cells.

Immunogold staining of primary cultures of human brain microvessel endothelial cells demonstrated the presence of Factor VIII-related antigen within cytoplasmic vesicles in close association with the rough endoplasmic reticulum and Golgi apparatus. Immunoperoxidase staining, at the light microscopic level, revealed a similar granular, perinuclear staining. The morphology and location of these vesicular profiles indicate that they are part of the trans-Golgi region where terminal processing and short-term storage of Factor VIII-related antigen takes place. Weibel-Palade bodies, specific storage organelles for von Willebrand factor in large vessel endothelium, were not observed in cerebral microvessel endothelium. The release of Factor VIII-related antigen from the cytoplasmic vesicles was influenced by some of the factors known to stimulate or inhibit the regulated pathway of secretion from Weibel-Palade bodies. Thus, stimulation of endothelial cells with calcium ionophore A23187 resulted in almost complete loss of staining, while addition of EGTA to the culture medium led to slight increase of intracellular pools of Factor VIII-related antigen. Pre-incubation of monolayers with interferon-gamma was associated with significant increase in the number of labeled vesicles, suggesting an additional role of this cytokine in the localized immune reaction within the central nervous system.

Brain↗

PubMed1991

Innervation of the zona fasciculata of the adult human adrenal cortex: a light and electron microscopic study.

Autonomic innervation of the adrenal cortex has been demonstrated in several species. Detailed ultrastructural studies on the innervation of the zona fasciculata of the normal human adrenal cortex are lacking. We report herein our observations on the pattern of innervation of the cells of the zona fasciculata of the normal adult human cortex at both the light and electron microscope levels. Postganglionic unmyelinated fibers were observed to descend from a dense capsular meshwork and to be distributed as delicate branches among the columns of endocrine cells. Immunoperoxidase staining confirmed the presence of nerve fibers in the zona fasciculata in a distribution similar to that observed after staining with silver impregnation methods. Ultrastructural findings lent further support to these observations by the demonstration of bundles of unmyelinated fibers with focal enlargements containing terminal boutons with both clear and dense core vesicles in close approximation with the endocrine cells.

Adult↗

PubMed1991

Neurologic complications in allogeneic bone marrow transplant patients receiving cyclosporin.

Regimens using cyclosporin (CSP) and either methylprednisolone (MP) or methotrexate (MTX) have been useful in the prophylaxis of acute graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT). However, CSP produces a number of side effects, including neurologic toxicity. A retrospective review of recipients of 239 BMTs given CSP-based prophylactic regimens revealed that 10 patients (4.2%, 95% confidence interval 0% to 10.4%) experienced a syndrome characterized by hypertension, severe visual disturbances, seizures and occipital lobe density changes on brain computed tomography (nine patients) or nuclear magnetic resonance imaging (one patient). Neurologic findings were reversible in all cases, usually after temporary discontinuation of CSP. Univariate analysis identified the following risk factors for neurotoxicity: use of unrelated or HLA-mismatched related donors, administration of etoposide (VP-16) or total body irradiation as part of conditioning, use of corticosteroids for prophylaxis or treatment of acute GVHD, or development of either acute GVHD or clinically significant microangiopathic hemolytic anemia (MAHA) post-BMT. In multivariate analysis, the most important predictors were the use of VP-16 (p = 0.008), the use of a continuous infusion CSP plus MP prophylactic regimen for GVHD (p = 0.003) and the development of MAHA after BMT (p less than 0.001). The strong association with MAHA suggests that endothelial damage is related to the development of this complication.

Adolescent↗

PubMed1991

Culture and characterization of microvascular endothelial cells derived from human brain.

Primary cultures of human cerebral endothelial cells were established from microvessels isolated from cortical fragments removed at surgery for seizure disorder and from brains at autopsy. A uniform population of cells growing in close association to each other formed confluent monolayers by 7 to 10 days in culture. They contained factor VIII/Von Willebrand antigen, the most specific marker for cells of endothelial origin, and showed lectin-binding sites for Ulex europaeus agglutinin characteristic of human endothelium. Cultured cells formed thin, continuous monolayers, contained few pinocytotic vesicles, and were joined together by tight junctional complexes. More than 99% of the intercellular junctions restricted the transendothelial passage of horseradish peroxidase. Monolayers of human brain microvessel endothelial cells thus resemble cerebral endothelium in vivo and should provide a useful in vitro model for studies of the biology of these cells and their role in the pathogenesis of certain human central nervous system diseases associated with abnormal blood-brain barrier function.

Capillary Permeability↗

PubMed1987

Hyperosmotic urea reversibly opens the tight junctions between brain capillary endothelial cells in cell culture.

The effect of hyperosmotic solutions of urea on primary cultures of bovine brain microvessel endothelial cells was examined. Confluent monolayers of cells positive for Factor VIII-related antigen were obtained by seven days in culture. The cells were: incubated in media containing 1 M, 2 M or 3 M urea and horseradish peroxidase (HRP) for various periods of time and then examined by transmission electron microscopy. Exposed to hypertonic urea solutions and 14C-3-O-methyl-D-glucose for determination of the intracellular water space. In control cultures endothelial cells were bound together by tight junctional complexes over 91% of which excluded HRP. In experimental cultures 82% of the interendothelial clefts became permeable to HRP after one minute of incubation with 3 M urea. The degree of cell shrinkage corresponded well with the extent of junctional opening. In monolayers examined 24 hours following removal of urea from the media more than 63% of the intercellular clefts were impermeable to HRP. These observations indicate that hyperosmotic solutions of urea reversibly open the tight junctions between brain microvessel endothelial cells in tissue culture. Decrease in cell volume appears to be linked to the increased junctional permeability.

Animals↗

PubMed1987

Increased adrenal weight in victims of violent suicide.

Adrenal weight was significantly higher in 16 victims of violent suicide than in 10 subjects who died suddenly from other causes. Since approximately half of suicide victims are depressed, these results support an association between depression and hypertrophy of the adrenal cortex.

Adrenal Glands↗

PubMed1987

Formation of a barrier by brain microvessel endothelial cells in culture.

Endothelial cells (EC) isolated from bovine brain microvessels produce a continuous monolayer when grown in primary culture. The EC are joined together by tight junctions and contain few pinocytotic vesicles. Horseradish peroxidase (HRP) is unable to penetrate this in vitro barrier system. Exposure of the cells to 1.6 M arabinose produces a reversible separation of the tight junctions with penetration of HRP across the monolayer in a pattern similar to that observed in animals after infusion of hyperosmotic solutions into the carotid artery. The behavior of brain microvascular cells in culture suggest that they retain properties important to the formation of the blood-brain barrier.

Animals↗

PubMed1986

Scalp neoplasm associated with cranium bifidum in a 24-week human fetus.

Prenatal ultrasonography at 24 weeks disclosed a fetus with a large mass protruding from the occiput. The mass was an invasive, undifferentiated mesenchymal neoplasm of the scalp associated with a defect in the occipital bone (cranium bifidum). The tumor may have derived from neural crest at the site of rhombencephalic closure. The tumor itself would seem to be a sporadic event, but the cranium bifidum may imply a recurrence risk of 2-3% for future pregnancies.

Adult↗

PubMed1986

In vitro studies of the blood-brain barrier using isolated brain capillaries and cultured endothelial cells.

The endothelial cells in brain capillaries are the anatomic site of the blood-brain barrier. To learn more about the biology of these specialized cells, we developed methods to prepare suspensions of purified brain microvessels as well as primary cultures of endothelial cells in monolayer. These two preparations allow for direct investigation of the metabolism, transport properties, and receptor content of the brain capillary. We used isolated brain microvessels to study distribution of membrane carriers between the luminal and the abluminal plasma membrane of endothelial cells. We found that Na+K+-ATPase and the A-system amino-acid transport system are located predominantly on the abluminal surface of brain capillary endothelial cells. This distribution of transport carriers is consistent with the low permeability of potassium and small neutral amino acids in the blood-to-brain direction. It suggests, however, that both solutes can be actively transported across brain capillaries from the brain interstitial fluid to the blood. In tissue culture, the endothelial cells form continuous tight junctions with their neighbors. This results in a cellular layer impermeable to protein tracers. When exposed to hyperosmolar solutions, in an attempt to mimic the conditions that open the blood-brain barrier in vivo, we found a reversible separation of the tight junctions between contiguous endothelial cells. No indication of activation of pinocytosis was observed. In vitro systems provide a novel approach for studying the function of the blood-brain barrier and allow for observations not possible with intact animals.

Animals↗

PubMed1986

The fibromatoses: CT-pathologic correlation.

Although CT has been used in the evaluation of benign fibroblastic tumors (fibromatoses), data are lacking on radiologic-histopathologic correlation. In an attempt to explain the variable CT appearance of these lesions, a retrospective analysis was carried out of CT findings and histopathologic features in nine patients with fibromatoses. In three of four patients who had precontrast CT scans, the tumors were hyperdense relative to muscle, whereas in one patient the lesion was hypodense. The postenhancement appearance was variable. The pathologic specimens were analyzed and graded for collagen content, cellular content, tumor necrosis, and tumor vascularity. No consistent relationship could be established between the CT appearance of these lesions and their histologic appearance.

Adult↗

PubMed1985

Correlations between aminergic metabolites simultaneously obtained from human CSF and brain.

Brain and cerebrospinal fluid (CSF) levels of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were simultaneously measured in 48 individuals at autopsy. Concentrations of 5-HIAA and HVA in the cerebral cortex were positively correlated with their levels in the CSF for the same individual. Additionally a positive correlation was observed between postmortem CSF levels of 5-HIAA and HVA and a significant concentration gradient for both metabolites was observed in serial fractions of CSF. These findings suggest that determinations of 5-HIAA and HVA in CSF from living individuals may reflect brain metabolite levels as well as the functional activity of these specific neuronal systems.

Adolescent↗

PubMed1984

Hyperosmotic arabinose solutions open the tight junctions between brain capillary endothelial cells in tissue culture.

Tight junctions between bovine brain capillary endothelial cells in primary cell culture are impermeable to horseradish peroxidase (HRP) after 5 min of incubation. However, following 1-5 min of exposure to 1.6 M arabinose, HRP penetrates the extracellular space between successive tight junctions. Endothelial cells in control cultures contain a small number of cytoplasmic pits and vesicles containing HRP which do not increase in number after hyperosmotic treatment.

Animals↗