Katerina Dorovini-zis - Academia.edu (original) (raw)

Papers by Katerina Dorovini-zis

Journal of Neuroinflammation, 2010

Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life wer... more Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life were graded according to convolutional development and compared with the microscopical development of kidneys and the gestational age as given by the mother. Excellent correlation was obtained between the gross appearance of the brain and the microscopical appearance of the kidney. The history of the mother mostly, but not always agreed with the anatomical appearance, which was considered a reliable guide to the gestational age of the infant.

Neurosurgery

A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cys... more A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old women presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed.

American Journal of Neuroradiology

Clinical neuropathology

Two patients are described with hyperammonemia due to ornithine transcarbamylase (OTC) deficiency... more Two patients are described with hyperammonemia due to ornithine transcarbamylase (OTC) deficiency who suffered severe shrinkage and collapse of the brain. The cerebral cortex was spongy and cavitated, containing only a few residual neurons, and was markedly gliosed. In one patient the basal ganglia were affected and harbored Alzheimer type II astrocytes. These lesions resemble those of acquired hepatocerebral degeneration and occur especially in female children with the milder form of the disease, who have a potential to survive. Strict observance of dietary restrictions is mandatory to avoid catastrophic damage to the brain.

Bone marrow transplantation, 1991

Regimens using cyclosporin (CSP) and either methylprednisolone (MP) or methotrexate (MTX) have be... more 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 ...

Blood-Brain Barrier,, 2003

The recruitment of leukocytes from the blood into secondary lymphoid and peripheral organs is a k... more The recruitment of leukocytes from the blood into secondary lymphoid and peripheral organs is a key process in both leukocyte homeostasis and the initiation and maintenance of immune responses (1). Within the past decade, several important advances have been ...

Obstetrical & Gynecological Survey, 1978

ABSTRACT Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal... more ABSTRACT Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life were graded according to convolutional development and compared with the microscopical development of kidneys and the gestational age as given by the mother. Excellent correlation was obtained between the gross appearance of the brain and the microscopical appearance of the kidney. The history of the mother mostly, but not always agreed with the anatomical appearance, which was considered a reliable guide to the gestational age of the infant.

Neurosurgery, 1985

A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft... more A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old women presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed.

Neurosurgery, 1985

ABSTRACT : A rare case of a pituitary adenoma found in association with a symptomatic Rathke&... more ABSTRACT : A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old woman presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed. (Neurosurgery 17:657-659, 1985) Copyright (C) by the Congress of Neurological Surgeons

Molecular Neurobiology, 2014

The macrophage migration inhibitory factor (MIF) is a multifaceted cytokine involved in many proc... more The macrophage migration inhibitory factor (MIF) is a multifaceted cytokine involved in many processes, including cellular responses to ischemia/reperfusion injury in the heart and brain. This study was undertaken to determine whether human MIF expression is induced following cerebral ischemia and its role therein. To examine whether the induction of MIF gene expression was mediated by its transcriptional upregulation, the human MIF gene promoter was cloned and a luciferase assay was used to determine the presence of a hypoxia-responsive region in the human MIF promoter. We found that human MIF promoter activity was significantly upregulated by hypoxia. A functional hypoxiainducible factor 1α-binding site was identified using an electrophoretic mobility shift assay (EMSA). MIF has a protective effect on cortical neurons under oxygen-glucose deprivation (OGD) treatment. MIF significantly reduced OGD-induced cell death. To determine whether the expression of MIF in the human brain is altered following ischemia, brain sections from 10 stroke patients were examined with an antibody against MIF. Blood vessel endothelial cells in the peri-infarct region of ischemic brain displayed strong MIF immunoreactivity with no MIF immunoreactivity in control brains. Furthermore, we found that treatment of human brain endothelial cells with MIF had no effect on human monocyte adhesion to endothelium. Our study demonstrates that MIF gene expression is altered during stroke and dysregulation of the hypoxia signaling-induced MIF expression plays an important role in neuronal death in stroke.

Journal of Infectious Diseases, 1992

An in vitro blood-brain barrier (BBB) model consisting of primary cultures of bovine brain microv... more 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.

Journal of Hepatology, 2000

The interaction of B7 molecules with their ligand provides important accessory signals for optima... more The interaction of B7 molecules with their ligand provides important accessory signals for optimal T cell activation and proliferation. In this study the in vitro expression of B7-1 and B7-2 by human brain microvessel endothelial cells (HBMEC) was investigated by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry. In addition, the contribution of B7 molecules to T cell proliferation on cerebral endothelial cells was studied by coincubating purified CD4+ T cells with resting or cytokine activated HBMEC. Untreated cultures constitutively expressed B7-2 RNA and surface protein, but lacked B7-1 expression. Treatment with TNF-alpha and IFN-gamma upregulated B7-2 and induced de novo expression of B7-1. Monoclonal blocking antibodies to B7-1 or B7-2 and human CTLA-4Ig chimeric protein significantly reduced the ability of HBMEC to support alpha-CD3-induced proliferation of CD4+ T lymphocytes. Expression of B7 glycoproteins and the ability to provide secondary signals for T cell proliferation suggest a potential role of the human cerebral endothelium in T cell activation during the early stages of central nervous system inflammation.

Journal of Neuropathology & …, 2004

Chemokines are key mediators of inflammation, acting as subset-specific chemoattractants and acti... more Chemokines are key mediators of inflammation, acting as subset-specific chemoattractants and activators of leukocytes. In the present study we investigated the effects of chemokine concentration gradients on CD4+ T cell (TC4) adhesion to human brain microvessel endothelial cells (HBMECs) in vitro. CCL4 or CCL5 were placed in a double chamber chemotaxis system beneath confluent resting HBMEC monolayers or cultures co-incubated with TNF-alpha and IFN-gamma to mimic an inflammatory milieu. Chemokines readily diffused across activated HBMEC monolayers while binding to the sub-endothelial regions, establishing a chemotactic and haptotactic gradient. Naïve or resting TC4 adhered poorly to resting HBMECs compared to memory or recently activated TC4, but all subsets adhered more readily to cytokine-treated HBMECs. Chemokine gradients (10-100 ng/ml) of both CCL4 and CCL5 significantly enhanced the adhesion of memory and recently activated TC4 to cytokine-treated HBMECs, as much as doubling adhesion in a manner that correlated with chemokine receptor expression. Neither chemokine influenced adhesion to resting HBMEC monolayers nor the adhesion of resting or naïve TC4. These findings emphasize the role and importance of CNS-derived beta-chemokines in regulating the traffic of recently activated TC subsets (those previously localized to the CNS in vivo) across cytokine-activated cerebral endothelium in inflammatory diseases.

The American Journal of Pathology, 2011

We examined the brains of 50 Malawian children who satisfied the clinical definition of cerebral ... more We examined the brains of 50 Malawian children who satisfied the clinical definition of cerebral malaria (CM) during life; 37 children had sequestration of infected red blood cells (iRBCs) and no other cause of death, and 13 had a nonmalarial cause of death with no cerebral sequestration. For comparison, 18 patients with coma and no parasitemia were included. We subdivided the 37 CM cases into two groups based on the cerebral microvasculature pathology: iRBC sequestration only (CM1) or sequestration with intravascular and perivascular pathology (CM2). We characterized and quantified the axonal and myelin damage, blood-brain barrier (BBB) disruption, and cellular immune responses and correlated these changes with iRBC sequestration and microvascular pathology. Axonal and myelin damage was associated with ring hemorrhages and vascular thrombosis in the cerebral and cerebellar white matter and brainstem of the CM2 cases. Diffuse axonal and myelin damage were present in CM1 and CM2 cases in areas of prominent iRBC sequestration. Disruption of the BBB was associated with ring hemorrhages and vascular thrombosis in CM2 cases and with sequestration in both CM1 and CM2 groups. Monocytes with phagocytosed hemozoin accumulated within microvessels containing iRBCs in CM2 cases but were not present in the adjacent neuropil. These findings are consistent with a link between iRBC © Sponsored Document Sponsored Document Sponsored Document sequestration and intravascular and perivascular pathology in fatal pediatric CM, resulting in myelin damage, axonal injury, and breakdown of the BBB.

Frontiers in Cellular and Infection Microbiology, 2015

The retinal and brain histopathological findings in children who died from cerebral malaria (CM) ... more The retinal and brain histopathological findings in children who died from cerebral malaria (CM) have been recently described. Similar changes occur in both structures, but the findings have not been directly compared in the same patients. In this study, we compared clinical retinal findings and retinal and cerebral histopathological changes in a series of patients in Blantyre, Malawi, who died of CM. The features systematically compared in the same patient were: (1) clinical, gross and microscopic retinal hemorrhages with microscopic cerebral hemorrhages, (2) retinal and cerebral hemorrhage-associated and -unassociated axonal damage, and fibrinogen leakage, and (3) differences in the above features between the pathological categories of CM without microvascular pathology (CM1) and CM with microvascular pathology (CM2) in retina and brain. Forty-seven patients were included: seven CM1, 28 CM2, and 12 controls. In the 35 malaria cases retinal and cerebral pathology correlated in all features except for non-hemorrhage associated fibrinogen leakage. Regarding CM1 and CM2 cases, the only differences were in the proportion of patients with hemorrhage-associated cerebral pathology, and this was expected, based on the definitions of CM1 and CM2. The retina did not show this difference. Non-hemorrhage associated pathology was similar for the two groups. As postulated, histopathological features of hemorrhages, axonal damage and non-hemorrhage associated fibrinogen leakage correlated in the retina and brain of individual patients, although the difference in hemorrhages between the CM1 and CM2 groups was not consistently observed in the retina. These results help to underpin the utility of ophthalmoscopic examination and fundus findings to help in diagnosis and assessment of cerebral malaria patients, but may not help in distinguishing between CM1 and CM2 patients during life.

Microvascular Research, 1999

2؉ ] i peak followed by a [Ca 2؉ ] i plateau. The [Ca 2؉ ] i plateau was blocked by the receptor-... more 2؉ ] i peak followed by a [Ca 2؉ ] i plateau. The [Ca 2؉ ] i plateau was blocked by the receptor-operated Ca 2؉ channel (ROC) blockers SK&F 96365 and NCDC, indicating a contribution by Ca 2؉ influx through ROC to the [Ca 2؉ ] i plateau. However, this [Ca 2؉ ] i plateau was not blocked by the voltage-gated Ca 2؉ channel (VGC) blocker diltiazem (DTZ). Depolarization with 80K ؉ or application of the VGC agonist BAY K 8644 did not alter the resting [Ca 2؉ ] i ; but 80K ؉ reduced the histamine (100 M) induced [Ca 2؉ ] i plateau. These results show that HCMEC are devoid of functional VGC. Thus the membrane potential (Em) regulates Ca 2؉ entry mainly by enhancing the electrochemical Ca 2؉ gradient, such that hyperpolarization increases while depolarization decreases [Ca 2؉ ] i . Blockade of sarcoplasmic/endoplasmic reticulum Ca 2؉ -ATPase (SERCA) by CPA increased [Ca 2؉ ] i . This effect was dependent on extracellular Ca 2؉ and reduced by iberiotoxin (IBTX) blockade of Ca 2؉ -activated K ؉ channels (Kca), suggesting a role for Kca in regulating Ca 2؉ influx.

Journal of Neuropathology and Experimental Neurology, 1995

Journal of Biological Chemistry, 2000

Tumor necrosis factor (TNF) does not cause endothelial apoptosis unless the expression of cytopro... more Tumor necrosis factor (TNF) does not cause endothelial apoptosis unless the expression of cytoprotective genes is blocked. We have previously demonstrated that one of the TNF-inducible cytoprotective genes is the Bcl-2 family member, A1. A1 is induced by the action of the transcription factor, NFB, in response to inflammatory mediators. In this report we demonstrate that, as with other cell types, inhibition of NFB initiates microvascular endothelial apoptosis in response to TNF. A1 is able to inhibit this apoptosis over 24 h. We demonstrate that A1 is localized to and functions at the mitochondria. Whereas A1 is able to inhibit mitochondrial depolarization, loss of cytochrome c, cleavage of caspase 9, BID, and poly(ADP-ribose) polymerase, it does not block caspase 8 or caspase 3 cleavage. In contrast, A1 is not able to prevent endothelial apoptosis by TNF over 72 h, when NFB signaling is blocked. On the other hand, the caspase inhibitor, benzyloxycarbonyl-VAD-formylmethyl ketone, completely blocks TNF-induced endothelial apoptosis over 72 h. Our findings indicate that A1 is able to maintain temporary survival of endothelial cells in response to TNF by maintaining mitochondrial viability and function. However, a mitochondria-independent caspase pathway eventually results in endothelial death despite mitochondrial protection by A1.

Experimental Parasitology, 1996

A. A., AND UDHAYAKU- MAR, V. 1996. Plasmodium falciparum: Involvement of additional receptors in ... more A. A., AND UDHAYAKU- MAR, V. 1996. Plasmodium falciparum: Involvement of additional receptors in the cytoadherence of infected erythrocytes to microvascular endothelial cells. Experimental Parasitology 84, 42-55. The involvement of additional ligands in the cytoadhesion of PRBC to endothelial cells was studied by the use of human microvascular endothelial cells (HMEC-1), brain microvascular endothelial cells (HBEC-5I), umbilical vein endothelial cells (HUVEC), and C32 melanoma cells as well as soluble CD36, ICAM-1, and thrombospondin in the adhesion assays. Immunostaining showed that ICAM-1 and thrombospondin were expressed by all cell lines, whereas CD36 and VCAM-1 were expressed constitutively only by C32 melanoma cells and HBEC-5I, respectively; none of these cells had basal expression of E-selectin. Bindings of the parental HB3 parasite strain to HMEC-1 and HUVEC were higher than that to HBEC-5I and C32 melanoma cells. Selections by panning the parental HB3 through HMEC-1 (HB3EC-6 line) or C32 melanoma cells (HB3C32-6 line) six times increased bindings by more than 10-fold, but the binding of HB3C32-6 to HMEC-1 was higher than that to C32 melanoma cells. Antibody or peptide blockade against CD36, ICAM-1, and thrombospondin or preincubation of target cells with TNF-a and IFN-g did not significantly alter the binding intensity of HB3EC-6 to HMEC-1 and HB3C32-6 to C32 melanoma cells. Preincubation of HMEC-1 with IL-4, however, reduced its binding with HB3EC-6. In vitro selection did not enhance the binding of PRBC to platebound CD36 or thrombospondin; binding to ICAM-1 was negligible. The binding of both selected lines was inhibited by dextran sulfate and sulfatides, but not by chondroitin sulfate A. These results suggested that in addition to CD36 and thrombospondin, sulfated glycoconjugates were probably concurrently utilized by these PRBC as receptors. Experiments with freshly isolated Kenyan parasites indicated that they also exhibited a similar mechanism of binding to endothelial cells. ᭧ 1996 Academic Press, Inc.

Journal of Neuroinflammation, 2010

Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life wer... more Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life were graded according to convolutional development and compared with the microscopical development of kidneys and the gestational age as given by the mother. Excellent correlation was obtained between the gross appearance of the brain and the microscopical appearance of the kidney. The history of the mother mostly, but not always agreed with the anatomical appearance, which was considered a reliable guide to the gestational age of the infant.

Neurosurgery

A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cys... more A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old women presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed.

American Journal of Neuroradiology

Clinical neuropathology

Two patients are described with hyperammonemia due to ornithine transcarbamylase (OTC) deficiency... more Two patients are described with hyperammonemia due to ornithine transcarbamylase (OTC) deficiency who suffered severe shrinkage and collapse of the brain. The cerebral cortex was spongy and cavitated, containing only a few residual neurons, and was markedly gliosed. In one patient the basal ganglia were affected and harbored Alzheimer type II astrocytes. These lesions resemble those of acquired hepatocerebral degeneration and occur especially in female children with the milder form of the disease, who have a potential to survive. Strict observance of dietary restrictions is mandatory to avoid catastrophic damage to the brain.

Bone marrow transplantation, 1991

Regimens using cyclosporin (CSP) and either methylprednisolone (MP) or methotrexate (MTX) have be... more 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 ...

Blood-Brain Barrier,, 2003

The recruitment of leukocytes from the blood into secondary lymphoid and peripheral organs is a k... more The recruitment of leukocytes from the blood into secondary lymphoid and peripheral organs is a key process in both leukocyte homeostasis and the initiation and maintenance of immune responses (1). Within the past decade, several important advances have been ...

Obstetrical & Gynecological Survey, 1978

ABSTRACT Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal... more ABSTRACT Eighty normal human brains varying from 22 weeks' gestation to 1 month postnatal life were graded according to convolutional development and compared with the microscopical development of kidneys and the gestational age as given by the mother. Excellent correlation was obtained between the gross appearance of the brain and the microscopical appearance of the kidney. The history of the mother mostly, but not always agreed with the anatomical appearance, which was considered a reliable guide to the gestational age of the infant.

Neurosurgery, 1985

A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft... more A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old women presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed.

Neurosurgery, 1985

ABSTRACT : A rare case of a pituitary adenoma found in association with a symptomatic Rathke&... more ABSTRACT : A rare case of a pituitary adenoma found in association with a symptomatic Rathke's cleft cyst in a 34-year-old woman presenting with headaches, visual symptoms, and amenorrhea is described. The diagnostic evaluation and operative treatment of these coincident lesions are discussed. (Neurosurgery 17:657-659, 1985) Copyright (C) by the Congress of Neurological Surgeons

Molecular Neurobiology, 2014

The macrophage migration inhibitory factor (MIF) is a multifaceted cytokine involved in many proc... more The macrophage migration inhibitory factor (MIF) is a multifaceted cytokine involved in many processes, including cellular responses to ischemia/reperfusion injury in the heart and brain. This study was undertaken to determine whether human MIF expression is induced following cerebral ischemia and its role therein. To examine whether the induction of MIF gene expression was mediated by its transcriptional upregulation, the human MIF gene promoter was cloned and a luciferase assay was used to determine the presence of a hypoxia-responsive region in the human MIF promoter. We found that human MIF promoter activity was significantly upregulated by hypoxia. A functional hypoxiainducible factor 1α-binding site was identified using an electrophoretic mobility shift assay (EMSA). MIF has a protective effect on cortical neurons under oxygen-glucose deprivation (OGD) treatment. MIF significantly reduced OGD-induced cell death. To determine whether the expression of MIF in the human brain is altered following ischemia, brain sections from 10 stroke patients were examined with an antibody against MIF. Blood vessel endothelial cells in the peri-infarct region of ischemic brain displayed strong MIF immunoreactivity with no MIF immunoreactivity in control brains. Furthermore, we found that treatment of human brain endothelial cells with MIF had no effect on human monocyte adhesion to endothelium. Our study demonstrates that MIF gene expression is altered during stroke and dysregulation of the hypoxia signaling-induced MIF expression plays an important role in neuronal death in stroke.

Journal of Infectious Diseases, 1992

An in vitro blood-brain barrier (BBB) model consisting of primary cultures of bovine brain microv... more 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.

Journal of Hepatology, 2000

The interaction of B7 molecules with their ligand provides important accessory signals for optima... more The interaction of B7 molecules with their ligand provides important accessory signals for optimal T cell activation and proliferation. In this study the in vitro expression of B7-1 and B7-2 by human brain microvessel endothelial cells (HBMEC) was investigated by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry. In addition, the contribution of B7 molecules to T cell proliferation on cerebral endothelial cells was studied by coincubating purified CD4+ T cells with resting or cytokine activated HBMEC. Untreated cultures constitutively expressed B7-2 RNA and surface protein, but lacked B7-1 expression. Treatment with TNF-alpha and IFN-gamma upregulated B7-2 and induced de novo expression of B7-1. Monoclonal blocking antibodies to B7-1 or B7-2 and human CTLA-4Ig chimeric protein significantly reduced the ability of HBMEC to support alpha-CD3-induced proliferation of CD4+ T lymphocytes. Expression of B7 glycoproteins and the ability to provide secondary signals for T cell proliferation suggest a potential role of the human cerebral endothelium in T cell activation during the early stages of central nervous system inflammation.

Journal of Neuropathology & …, 2004

Chemokines are key mediators of inflammation, acting as subset-specific chemoattractants and acti... more Chemokines are key mediators of inflammation, acting as subset-specific chemoattractants and activators of leukocytes. In the present study we investigated the effects of chemokine concentration gradients on CD4+ T cell (TC4) adhesion to human brain microvessel endothelial cells (HBMECs) in vitro. CCL4 or CCL5 were placed in a double chamber chemotaxis system beneath confluent resting HBMEC monolayers or cultures co-incubated with TNF-alpha and IFN-gamma to mimic an inflammatory milieu. Chemokines readily diffused across activated HBMEC monolayers while binding to the sub-endothelial regions, establishing a chemotactic and haptotactic gradient. Naïve or resting TC4 adhered poorly to resting HBMECs compared to memory or recently activated TC4, but all subsets adhered more readily to cytokine-treated HBMECs. Chemokine gradients (10-100 ng/ml) of both CCL4 and CCL5 significantly enhanced the adhesion of memory and recently activated TC4 to cytokine-treated HBMECs, as much as doubling adhesion in a manner that correlated with chemokine receptor expression. Neither chemokine influenced adhesion to resting HBMEC monolayers nor the adhesion of resting or naïve TC4. These findings emphasize the role and importance of CNS-derived beta-chemokines in regulating the traffic of recently activated TC subsets (those previously localized to the CNS in vivo) across cytokine-activated cerebral endothelium in inflammatory diseases.

The American Journal of Pathology, 2011

We examined the brains of 50 Malawian children who satisfied the clinical definition of cerebral ... more We examined the brains of 50 Malawian children who satisfied the clinical definition of cerebral malaria (CM) during life; 37 children had sequestration of infected red blood cells (iRBCs) and no other cause of death, and 13 had a nonmalarial cause of death with no cerebral sequestration. For comparison, 18 patients with coma and no parasitemia were included. We subdivided the 37 CM cases into two groups based on the cerebral microvasculature pathology: iRBC sequestration only (CM1) or sequestration with intravascular and perivascular pathology (CM2). We characterized and quantified the axonal and myelin damage, blood-brain barrier (BBB) disruption, and cellular immune responses and correlated these changes with iRBC sequestration and microvascular pathology. Axonal and myelin damage was associated with ring hemorrhages and vascular thrombosis in the cerebral and cerebellar white matter and brainstem of the CM2 cases. Diffuse axonal and myelin damage were present in CM1 and CM2 cases in areas of prominent iRBC sequestration. Disruption of the BBB was associated with ring hemorrhages and vascular thrombosis in CM2 cases and with sequestration in both CM1 and CM2 groups. Monocytes with phagocytosed hemozoin accumulated within microvessels containing iRBCs in CM2 cases but were not present in the adjacent neuropil. These findings are consistent with a link between iRBC © Sponsored Document Sponsored Document Sponsored Document sequestration and intravascular and perivascular pathology in fatal pediatric CM, resulting in myelin damage, axonal injury, and breakdown of the BBB.

Frontiers in Cellular and Infection Microbiology, 2015

The retinal and brain histopathological findings in children who died from cerebral malaria (CM) ... more The retinal and brain histopathological findings in children who died from cerebral malaria (CM) have been recently described. Similar changes occur in both structures, but the findings have not been directly compared in the same patients. In this study, we compared clinical retinal findings and retinal and cerebral histopathological changes in a series of patients in Blantyre, Malawi, who died of CM. The features systematically compared in the same patient were: (1) clinical, gross and microscopic retinal hemorrhages with microscopic cerebral hemorrhages, (2) retinal and cerebral hemorrhage-associated and -unassociated axonal damage, and fibrinogen leakage, and (3) differences in the above features between the pathological categories of CM without microvascular pathology (CM1) and CM with microvascular pathology (CM2) in retina and brain. Forty-seven patients were included: seven CM1, 28 CM2, and 12 controls. In the 35 malaria cases retinal and cerebral pathology correlated in all features except for non-hemorrhage associated fibrinogen leakage. Regarding CM1 and CM2 cases, the only differences were in the proportion of patients with hemorrhage-associated cerebral pathology, and this was expected, based on the definitions of CM1 and CM2. The retina did not show this difference. Non-hemorrhage associated pathology was similar for the two groups. As postulated, histopathological features of hemorrhages, axonal damage and non-hemorrhage associated fibrinogen leakage correlated in the retina and brain of individual patients, although the difference in hemorrhages between the CM1 and CM2 groups was not consistently observed in the retina. These results help to underpin the utility of ophthalmoscopic examination and fundus findings to help in diagnosis and assessment of cerebral malaria patients, but may not help in distinguishing between CM1 and CM2 patients during life.

Microvascular Research, 1999

2؉ ] i peak followed by a [Ca 2؉ ] i plateau. The [Ca 2؉ ] i plateau was blocked by the receptor-... more 2؉ ] i peak followed by a [Ca 2؉ ] i plateau. The [Ca 2؉ ] i plateau was blocked by the receptor-operated Ca 2؉ channel (ROC) blockers SK&F 96365 and NCDC, indicating a contribution by Ca 2؉ influx through ROC to the [Ca 2؉ ] i plateau. However, this [Ca 2؉ ] i plateau was not blocked by the voltage-gated Ca 2؉ channel (VGC) blocker diltiazem (DTZ). Depolarization with 80K ؉ or application of the VGC agonist BAY K 8644 did not alter the resting [Ca 2؉ ] i ; but 80K ؉ reduced the histamine (100 M) induced [Ca 2؉ ] i plateau. These results show that HCMEC are devoid of functional VGC. Thus the membrane potential (Em) regulates Ca 2؉ entry mainly by enhancing the electrochemical Ca 2؉ gradient, such that hyperpolarization increases while depolarization decreases [Ca 2؉ ] i . Blockade of sarcoplasmic/endoplasmic reticulum Ca 2؉ -ATPase (SERCA) by CPA increased [Ca 2؉ ] i . This effect was dependent on extracellular Ca 2؉ and reduced by iberiotoxin (IBTX) blockade of Ca 2؉ -activated K ؉ channels (Kca), suggesting a role for Kca in regulating Ca 2؉ influx.

Journal of Neuropathology and Experimental Neurology, 1995

Journal of Biological Chemistry, 2000

Tumor necrosis factor (TNF) does not cause endothelial apoptosis unless the expression of cytopro... more Tumor necrosis factor (TNF) does not cause endothelial apoptosis unless the expression of cytoprotective genes is blocked. We have previously demonstrated that one of the TNF-inducible cytoprotective genes is the Bcl-2 family member, A1. A1 is induced by the action of the transcription factor, NFB, in response to inflammatory mediators. In this report we demonstrate that, as with other cell types, inhibition of NFB initiates microvascular endothelial apoptosis in response to TNF. A1 is able to inhibit this apoptosis over 24 h. We demonstrate that A1 is localized to and functions at the mitochondria. Whereas A1 is able to inhibit mitochondrial depolarization, loss of cytochrome c, cleavage of caspase 9, BID, and poly(ADP-ribose) polymerase, it does not block caspase 8 or caspase 3 cleavage. In contrast, A1 is not able to prevent endothelial apoptosis by TNF over 72 h, when NFB signaling is blocked. On the other hand, the caspase inhibitor, benzyloxycarbonyl-VAD-formylmethyl ketone, completely blocks TNF-induced endothelial apoptosis over 72 h. Our findings indicate that A1 is able to maintain temporary survival of endothelial cells in response to TNF by maintaining mitochondrial viability and function. However, a mitochondria-independent caspase pathway eventually results in endothelial death despite mitochondrial protection by A1.

Experimental Parasitology, 1996

A. A., AND UDHAYAKU- MAR, V. 1996. Plasmodium falciparum: Involvement of additional receptors in ... more A. A., AND UDHAYAKU- MAR, V. 1996. Plasmodium falciparum: Involvement of additional receptors in the cytoadherence of infected erythrocytes to microvascular endothelial cells. Experimental Parasitology 84, 42-55. The involvement of additional ligands in the cytoadhesion of PRBC to endothelial cells was studied by the use of human microvascular endothelial cells (HMEC-1), brain microvascular endothelial cells (HBEC-5I), umbilical vein endothelial cells (HUVEC), and C32 melanoma cells as well as soluble CD36, ICAM-1, and thrombospondin in the adhesion assays. Immunostaining showed that ICAM-1 and thrombospondin were expressed by all cell lines, whereas CD36 and VCAM-1 were expressed constitutively only by C32 melanoma cells and HBEC-5I, respectively; none of these cells had basal expression of E-selectin. Bindings of the parental HB3 parasite strain to HMEC-1 and HUVEC were higher than that to HBEC-5I and C32 melanoma cells. Selections by panning the parental HB3 through HMEC-1 (HB3EC-6 line) or C32 melanoma cells (HB3C32-6 line) six times increased bindings by more than 10-fold, but the binding of HB3C32-6 to HMEC-1 was higher than that to C32 melanoma cells. Antibody or peptide blockade against CD36, ICAM-1, and thrombospondin or preincubation of target cells with TNF-a and IFN-g did not significantly alter the binding intensity of HB3EC-6 to HMEC-1 and HB3C32-6 to C32 melanoma cells. Preincubation of HMEC-1 with IL-4, however, reduced its binding with HB3EC-6. In vitro selection did not enhance the binding of PRBC to platebound CD36 or thrombospondin; binding to ICAM-1 was negligible. The binding of both selected lines was inhibited by dextran sulfate and sulfatides, but not by chondroitin sulfate A. These results suggested that in addition to CD36 and thrombospondin, sulfated glycoconjugates were probably concurrently utilized by these PRBC as receptors. Experiments with freshly isolated Kenyan parasites indicated that they also exhibited a similar mechanism of binding to endothelial cells. ᭧ 1996 Academic Press, Inc.