Biomedical subjects

V K Kalra

Publications and source records attributed to V K Kalra.

At least 19 recordsLinked to original sources

PubMed2001

Gp120 activates children's brain endothelial cells via CD4.

Encephalopathy represents a common and serious manifestation of HIV-1 infection in children, but its pathogenesis is unclear. We demonstrated that gp120 activated human brain microvascular endothelial cells (HBMEC) derived from children in up-regulating ICAM-1 and VCAM-1 expression, IL-6 secretion and increased monocyte transmigration across monolayers. Another novel observation was our demonstration of CD4 in isolated HBMEC and on microvessels of children's brain cryosections. Gp120-induced monocyte migration was inhibited by anti-gp120 and anti-CD4 antibodies. This is the first demonstration that gp120 activates HBMEC via CD4, which may contribute to the development of HIV-1 encephalopathy in children.

AIDS Dementia Complex↗

PubMed2000

beta-amyloid-induced migration of monocytes across human brain endothelial cells involves RAGE and PECAM-1.

In patients with amyloid beta-related cerebrovascular disorders, e.g. , Alzheimer's disease, one finds increased deposition of amyloid peptide (Abeta) and increased presence of monocyte/microglia cells in the brain. However, relatively little is known of the role of Abeta in the trafficking of monocytes across the blood-brain barrier (BBB). Our studies show that interaction of Abeta(1-40) with monolayer of human brain endothelial cells results in augmented adhesion and transendothelial migration of monocytic cells (THP-1 and HL-60) and peripheral blood monocytes. The Abeta-mediated migration of monocytes was inhibited by antibody to Abeta receptor (RAGE) and platelet endothelial cell adhesion molecule (PECAM-1). Additionally, Abeta-induced transendothelial migration of monocytes were inhibited by protein kinase C inhibitor and augmented by phosphatase inhibitor. We conclude that interaction of Abeta with RAGE expressed on brain endothelial cells initiates cellular signaling leading to the transendothelial migration of monocytes. We suggest that increased diapedesis of monocytes across the BBB in response to Abeta present either in the peripheral circulation or in the brain parenchyma may play a role in the pathophysiology of Abeta-related vascular disorder.

Adult↗

PubMed1999

Cobalt chloride-induced signaling in endothelium leading to the augmented adherence of sickle red blood cells and transendothelial migration of monocyte-like HL-60 cells is blocked by PAF-receptor antagonist.

In response to hypoxia, sickle red blood cells (SS RBC) and leukocytes exhibit increased adherence to the vascular endothelium, while diapedesis of leukocytes through the blood vessel increases. However, the cellular signaling pathway(s) caused by hypoxia is poorly understood. We utilized CoCl2 as a mimetic molecule for hypoxia to study cellular signaling pathways. We found that in human umbilical vein endothelial cells (HUVEC), CoCl2 at 2 mM concentration induced the surface expression of a subset of CAMs (VCAM-1) and activation of transcription factor NF-kappaB in the nuclear extracts of HUVEC. Furthermore, CoCl2 also caused time-dependent tyrosine phosphorylation of mitogen-activated protein (MAP) kinase isoform ERK2 without significantly affecting ERK1, indicating ERK2 is the preferred substrate for upstream kinase of the MAPK pathway. Inhibitors of MAP kinase (PD98059) or platelet-activating factor (PAF)- receptor antagonist (CV3988) inhibited the CoCl2-induced NF-kappaB activation and VCAM-1 expression. Augmented expression of VCAM-1 led to increased SS RBC adhesion, inhibitable by a VCAM-1 antibody. Additionally, CoCl2 caused a two- to threefold increase in the rate of transendothelial migration of monocyte-like HL-60 cells and a twentyfold increase in phosphorylation of platelet endothelial cell adhesion molecules (PECAM-1). The transendothelial migration of monocytes was inhibited by an antibody to PECAM-1. Both phosphorylation of PECAM-1 and transendothelial migration of monocytes in response to CoCl2 were inhibited by protein kinase inhibitor (GF109203X) and augmented by protein phosphatase inhibitor (Calyculin A). Our data suggests that CoCl2-induced cellular signals directing increased expression of VCAM-1 in HUVEC involve downstream activation of MAP kinase and NF-kappaB, while the phosphorylation of PECAM-1 occurs as a result of activation of PKC. We conclude that PAF-receptor antagonist inhibits the CoCl2- or hypoxia-induced increase in the adhesion of SS RBC, PECAM-1 phosphorylation, and the concomitant transendothelial migration of monocytes.

Adult↗

PubMed1999

Stimulation of macrophages by retinal proteins: production of reactive nitrogen and oxygen metabolites.

PURPOSE: In previous work, it has been shown that in experimental autoimmune uveitis, the peroxynitrite-mediated protein nitration product nitrotyrosine was localized in the degenerating photoreceptors. Subsequently, phagocyte-generated inducible nitric oxide synthase (iNOS) was also found to localize, primarily in the outer retina and to a lesser extent in the anterior segments. This study was intended to determine whether retinal soluble proteins such as S-antigen and interphotoreceptor retinoid-binding protein (IRBP) play a role in the induction of *NO and superoxide by a macrophage cell line and by rat and rabbit peritoneal macrophages. METHODS: Cells from the murine macrophage cell line RAW 264.7 and rat and rabbit peritoneal macrophages were incubated in the presence of retinal soluble proteins. The nitrite level in the cultured supernatant was evaluated for *NO production using the Griess reaction. Activation of nuclear transcription factor kappaB (NF-kappaB) was determined by electrophoretic mobility shift assay. Superoxide production was measured by superoxide dismutase-inhibitable reduction of cytochrome C. RESULTS: Both S-antigen and IRBP induced significant, dose-dependent nitrite production in RAW 264.7 and rat peritoneal macrophages. Induction of iNOS by retinal proteins was inhibited by the iNOS-specific inhibitor aminoguanidine and the tyrosine kinase inhibitor genistein. This iNOS induction was accompanied by the activation of NF-kappaB. S-antigen also induced superoxide production in rabbit peritoneal macrophages, but not in RAW 264.7. CONCLUSIONS: These results show that soluble retinal proteins significantly induce *NO and superoxide production by macrophages. Increased production of reactive oxygen species by macrophages in the presence of these soluble retinal proteins in vivo may accelerate photoreceptor degeneration in uveitis.

Amino Acid Sequence↗

PubMed1998

Interaction of sickle erythrocytes with endothelial cells in the presence of endothelial cell conditioned medium induces oxidant stress leading to transendothelial migration of monocytes.

The abnormal adherence of sickle red blood cells (SS RBC) to endothelial cells has been thought to contribute to vascular occlusion, a major cause of morbidity in sickle cell disease (SCD). We determined whether the interaction of SS RBC with cultured endothelial cells induced cellular oxidant stress that would culminate in expression of cell adhesion molecules (CAMs) involved in the adhesion and diapedesis of monocytes and the adherence of SS reticulocytes. We showed that the interaction of SS RBC at 2% concentration in the presence of multimers of von Willebrand factor (vWf), derived from endothelial cell-derived conditioned medium (E-CM) with cultured human umbilical vein endothelial cells (HUVEC), resulted in a fivefold increased formation of thiobarbituric acid-reactive substances (TBARS) and activation of the transcription factor NF-kB, both indicators of cellular oxidant stress. Normal RBC show none of these phenomena. The oxidant stress-induced signaling resulted in an increased surface expression of a subset of CAMs, ICAM-1, E-selectin, and VCAM-1 in HUVEC. The addition of oxygen radical scavenger enzymes (catalase, superoxide dismutase) and antioxidant (probucol) inhibited these events. Additionally, preincubation of HUVEC with a synthetic peptide Arg-Gly-Asp (RGD) that prevents vWf-mediated adhesion of SS RBC reduced the surface expression of VCAM-1 and NF-kB activation. Furthermore, SS RBC-induced oxidant stress resulted in a twofold increase in the transendothelial migration of both monocyte-like HL-60 cells and human peripheral blood monocytes, and approximately a sixfold increase in platelet-endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation, each of which was blocked by protein kinase C inhibitor and antioxidants. These results suggest that the adherence/contact of SS RBC to endothelial cells in large vessel can generate enhanced oxidant stress leading to increased adhesion and diapedesis of monocytes, as well as heightened adherence of SS reticulocytes, indicating that injury/activation of endothelium can contribute to vaso-occlusion in SCD.

Anemia, Sickle Cell↗

PubMed1998

Endotoxin-induced migration of monocytes and PECAM-1 phosphorylation are abrogated by PAF receptor antagonists.

The trafficking of monocytes across the endothelial lining of the blood vessel increases in response to bacterial infection at sites of inflammation. However, the molecular events involved in the diapedesis of monocytes in response to endotoxin are not completely understood. Our studies revealed that signaling by lipopolysaccharide (LPS) in human umbilical vein endothelial cells (HUVEC) resulted in a threefold increase in the transendothelial migration of monocyte-like HL-60 cells and a sevenfold increase in the phosphorylation of platelet endothelial cell adhesion molecule-1 (PECAM-1). The transmigration induced by LPS was inhibited by an antibody to PECAM-1. Both the phosphorylation of PECAM-1 and transendothelial migration of monocytes were inhibited by a platelet-activating factor (PAF) receptor antagonist, indicating the autocrine effect of PAF in these events. Treatment of HUVEC with LPS caused a fourfold increase in PAF receptor mRNA expression that was completely blocked by the PAF receptor antagonist. We conclude that PAF, generated by HUVEC in response to LPS or gram-negative bacterial infection, acts in an autocrine manner, causing PECAM-1 phosphorylation and thus the transendothelial migration of monocytes.

Azepines↗

PubMed1997

Diabetic RBC-induced oxidant stress leads to transendothelial migration of monocyte-like HL-60 cells.

Red blood cells (RBC) from patients with diabetes mellitus exhibit an increased propensity to adhere to cultured human umbilical vein endothelial cells (HUVEC) as a result of interaction of advanced glycation end products with their counter receptors, contributing to the pathogenesis of vascular complications. We determined whether the interaction of diabetic RBC with HUVEC induced cellular oxidant stress that would culminate in adherence and diapedesis of monocytes, these being initiating events in endothelial injury and atherogenesis. We show that the adherence of diabetic RBC (2% hematocrit), but not normal RBC, to HUVEC results in a fourfold increase in the production of lipid peroxides. Furthermore, diabetic RBC-induced oxidant stress causes a sixfold increase in platelet endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation and doubles transendothelial migration of monocyte-like HL-60 cells; both are blocked by antioxidants and protein kinase C (PKC) inhibitors. Our results show that the adherence of diabetic RBC to endothelial cells initiates a cascade of cellular events resulting in PKC activation, causing PECAM-1 phosphorylation and concomitant transendothelial migration of monocytes. The increased diapedesis of monocytes, brought about by the interaction of diabetic RBC across vascular endothelium, may play an important role in accelerated atherosclerosis and cardiovascular disease in diabetics.

Antioxidants↗

PubMed1997

Oxidant stress-induced transendothelial migration of monocytes is linked to phosphorylation of PECAM-1.

Reactive oxygen species (ROS) are believed to cause vascular injury in the pathophysiology of atherosclerosis, diabetes, and vasoocclusion in sickle cell disease. Studies have shown that ROS causes increased adhesion of monocytes and neutrophils to the endothelium. We investigated the effects of tert-butylhydroperoxide (t-BuOOH), an inducer of oxidant stress, to determine the cellular signaling pathway leading to the transendothelial migration of polymorphonuclear leukocytes. Our studies revealed that signaling by t-BuOOH in human umbilical vein endothelial cells (HUVECs) causes a twofold increase in the transendothelial migration of monocyte-like HL-60 cells and a fivefold increase in platelet endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation. The transmigration induced by t-BuOOH was inhibited by an antibody to PECAM-1. These events were inhibited by antioxidants and inhibitors of protein kinase C, p21ras and glutathione synthesis. However, treatment of HUVECs with the phosphatase inhibitor calyculin A augmented the t-BuOOH-mediated transendothelial migration of monocytes and PECAM-1 phosphorylation. Our results suggest that oxidative stress can induce the transendothelial migration of monocytes as a result of phosphorylation of PECAM-1, a crucial event in the diapedesis of leukocytes during pathophysiology of vascular diseases.

Adenine↗

PubMed1996

Sickle erythrocytes adhere to polymorphonuclear neutrophils and activate the neutrophil respiratory burst.

The vasoocclusive process in patients with sickle cell disease (SCD) is complex and involves interactions among sickle erythrocytes (SS-RBC), vascular endothelium, and plasma and cellular components. The role of neutrophils (PMN) in vasoocclusion has not been examined. Patients with SCD appear to have chronically activated PMN. Because the first step in PMN activation is particle recognition, we explored whether normal PMN recognize SS-RBC and whether this recognition results in PMN monolayers, significantly more SS-RBC adhered to the PMN than did normal erythrocytes (AA-RBC; P < .001). Preincubation of erythrocytes with autologous plasma significantly increased the adherence of SS-RBC to PMN but had no effect on AA-RBC (P < .001). When adhesion of density fractionated SS-RBC was performed, dense SS-RBC showed greater adherence to the PMN monolayers than did light SS-RBC (P < .001). To determine mechanisms of this adhesion, IgG and Arg-Gly-Asp-Ser (RGDS) receptor sites on PMN were saturated. IgG inhibited adherence of dense SS-RBC, whereas RGDS inhibited adherence in both fractions, although to a greater extent in the light fraction. We measured SS-RBC activation of PMN by incubating SS-RBC with 2', 7'-Dichloro-fluroescin Diacetate (DCF)-labeled PMN. Incubation of PMN with SS-RBC resulted in a significant increase in fluorescence compared to AA-RBC. We show here that PMN recognize SS-RBC through multiple mechanisms and that this recognition results in activation of PMN. These findings contribute to the understanding of vasoocclusive crisis in patients with SCD and may have therapeutic implications.

Amino Acid Sequence↗

PubMed1996

Lipoxygenase metabolites induced expression of adhesion molecules and transendothelial migration of monocyte-like HL-60 cells is linked to protein kinase C activation.

Studies have shown that, among lipoxygenase metabolites examined, 15(S)-hydroperoxy-5,8,11,13-eicosa-tetraenoic acid (15[S]-HPETE), at micromolar concentrations, selectively causes injury to cultured endothelial cells. We investigated whether physiologically relevant concentrations of lipoxygenase metabolites affected the expression of cell adhesion molecules (CAMs) involved in the adhesion of leukocytes and/or the accumulation of leukocytes in the vascular endothelium, these being the initial events in endothelial cell injury. Among lipoxygenase metabolites, 15(S)-HPETE and 12(S)-HETE, at nanomolar concentrations, induced surface expression of a subset of cell adhesion molecules (CAM), ICAM-1, ELAM-1, and VCAM-1, in human umbilical vein endothelial cells (HUVEC), which is associated with an increased binding activity of the transcription factor, NF-kappa B, to the consensus motif common to the CAM genes in the HUVEC nuclear extracts. Furthermore, 15(S)-HPETE (1 nM) caused a threefold increase in the rate of transendothelial migration of vitamin D3-differentiated HL-60 monocyte-like cells and showed a thirtyfold increase in the phosphorylation of PECAM-1, an adhesion molecule involved in endothelial cell-cell adhesion. Both an antibody to PECAM-1 and the protein kinase C inhibitor, GF 109203X, reduced 15(S)-HPETE-induced transmigration of monocyte-like HL-60 cells by approximately 75% and 85%, respectively. Treatment of HUVEC with a phosphatase inhibitor, calyculin A, augmented both the phosphorylation of PECAM-1 and transmigration of monocyte-like HL-60 cells induced by 15(S)-HPETE. Our results show that 15(S)-HPETE, at physiological concentrations, induced activation of protein kinase C in HUVEC and leads to the phosphorylation of PECAM-1, thus facilitating the migration of monocyte-like HL-60 cells across the endothelial cell monolayer. It is suggested that phosphorylation/dephosphorylation events in PECAM-1 are important in regulating the trafficking of monocytes across the endothelial cell monolayer.

Animals↗

PubMed1996

Glucose-induced transmigration of monocytes is linked to phosphorylation of PECAM-1 in cultured endothelial cells.

The adherence of circulating monocytes to the endothelium, their migration into the subendothelium, and the subsequent formation of foam cells are initial events in the pathogenesis of atherosclerosis. However, the effect of hyperglycemia on the transendothelial migration of monocytes is not known. Exposure of human umbilical vein endothelial cells (HUVEC) cultured in a Transwell chamber to 25 mM D-glucose (a concentration representing a hyperglycemic state) for 2 h resulted in a twofold increase in the migration of vitamin D3-differentiated monocyte-like HL-60 cells. The migration was inhibited by addition of either an antibody to platelet-endothelial cell adhesion molecule-1 (PECAM-1) or a protein kinase C inhibitor, GF-109203X. In HUVEC, high concentrations of D-glucose (25 mM), but not of other sugars such as L-glucose, 2-deoxyglucose, D-galactose, or D-mannitol, caused a sevenfold increase in the phosphorylation of PECAM-1 as a result of activation of protein kinase C. The 25 mM D-glucose-induced PECAM-1 phosphorylation and transmigration of monocyte-like HL-60 cells were further increased by treatment of HUVEC with the phosphatase inhibitor calyculin A. These results suggest that direct phosphorylation of PECAM-1 in response to elevated glucose promotes transendothelial migration of monocytes, contributing to accelerated atherogenesis in diabetics.

Cell Movement↗

PubMed1996

Cigarette smoke condensate-induced adhesion molecule expression and transendothelial migration of monocytes.

Cigarette smoking is clearly linked with increased incidence of atherosclerosis and cardiovascular disease. The adherence of blood monocytes to the endothelium, followed by their migration beneath the endothelium, are initiating events in the formation of foam cells, promoting atherogenesis. We show that cigarette smoke condensate (CSC)-induced surface expression of a subset of cell adhesion molecules (CAM) [intercellular adhesion molecule 1 (ICAM-1), endothelial leukocyte adhesion molecule 1 (ELAM-1), and vascular cell adhesion molecule 1 (VCAM-1)] in human umbilical vein endothelial cells (HUVEC) is associated with an increase in the binding activity of nuclear transcription factor NF-kappa B to the consensus motif common to the CAM genes. Furthermore, CSC (25 microgram/ml) both increases the rate of transendothelial migration of vitamin D3-differentiated monocyte-like cells across the HUVEC monolayer by 200% and causes an approximately 10-fold increases in the phosphorylation of platelet endothelial CAM (PECAM-1), an adhesion molecule located at intercellular junctions and involved in endothelial cell-cell adhesion. Our results show that CSC-induced activation of protein kinase C in endothelial cells initiates a signaling pathways, leading to heightened binding of NF-kappa B to specific DNA sequences, which in turn increases surface expression of the subset of CAMs. Furthermore, our studies demonstrate a link between the phosphorylation of PECAM-1 and the migration of blood monocytes across vascular endothelium.

Animals↗

PubMed1996

Hypoxia induces PECAM-1 phosphorylation and transendothelial migration of monocytes.

Polymorphonuclear neutrophils (PMN) adhere to the vascular endothelium under hypoxic conditions, causing microvascular injury. The molecular mechanism of hypoxia-induced adhesion of PMN to and diapedesis through the vascular endothelium is poorly understood. We examined the effects of hypoxia on the transendothelial migration of monocytes. Exposure of human umbilical vein endothelial cells (HUVEC) cultured in Transwell chambers under low oxygen tension (3% O2 compared with 21% O2) resulted in an increased rate of migration of both monocyte-like HL-60 cells and human peripheral blood monocytes. Migration was inhibited by addition of an antibody to platelet endothelial cell adhesion molecule-1 (PECAM-1), a protein kinase C (PKC) inhibitor, or a platelet-activating factor (PAF)-receptor antagonist. In HUVEC, hypoxic conditions (1, 3, 5, and 14% O2) increased the phosphorylation of PECAM-1. The extent of phosphorylation of PECAM-1 was inversely related to the concentration of oxygen to which HUVEC were exposed. Hypoxia-induced phosphorylation of PECAM-1 was inhibited by either a PKC inhibitor or a PAF-receptor antagonist, indicating the involvement of hypoxia-induced release of PAF in both PKC activation and the concomitant phosphorylation of PECAM-1. These results were substantiated by the findings that treatment of HUVEC with 100 nM PAF under normoxic conditions augmented 11.8-fold the phosphorylation of PECAM-1 and twofold increase in the transendothelial migration of monocyte-like HL-60 cells. We conclude that PAF, produced by cultured endothelial cells in response to hypoxia, acts in an autocrine fashion to activate PKC, causing PECAM-1 phosphorylation and thus the transendothelial migration of monocytes.

Cell Movement↗

PubMed1994

Mechanism of cigarette smoke condensate induced adhesion of human monocytes to cultured endothelial cells.

Cigarette smoking is ranked among the leading risk factors in the etiology of atherosclerotic vascular disease. The mechanisms, however, that link cigarette smoking to increased incidence of atherosclerosis are not understood. The adherence of circulating monocytes to the endothelium, migration into the subendothelium, and subsequent formation of foam cells are principal initial events in the development of atherosclerosis. We therefore determined whether cigarette smoke caused increased adherence of monocytes to endothelial cells and the cellular mechanism of this increased adherence. Cigarette smoke condensate (CSC), the particulate fraction of cigarette smoke derived from 2R1 standard research cigarettes, at a concentration of 25-30 micrograms/ml (average yield of CSC is 26.1 mg/cigarette), augmented (70-90%) basal adherence of human peripheral blood monocytes to a cultured monolayer of endothelial cells derived from bovine aorta (BAEC) and human umbilical vein (HUVEC). There was a concomitant increase in the expression of CD11b ligand on the surface of monocytes as determined by flow cytometry, utilizing FITC conjugated Mab MO-1 (CD11b). However, nicotine (1-15 micrograms/ml) and cadmium sulfate (10 micrograms/ml), constituents of CSC, individually or in combination had no effect either on CD11b expression or adherence of monocytes to endothelial cells. Treatment of HUVEC with CSC for 60 min also resulted in an increased expression of ICAM-1 and ELAM-1 as determined by mean fluorescence intensity of ICAM-1 and ELAM-1 labeled cells in flow cytometric analysis. The CSC induced expression of CD11b in monocytes was optimal at 25-30 min and was inhibited by protein kinase C inhibitors, staurosporine and H-7, and also by baicalein, a lipoxygenase inhibitor. Similarly, CSC induced ICAM-1 and ELAM-1 expression in HUVEC was inhibited by protein kinase C inhibitors. CSC stimulated the adherence of human monocytes but not the monocytic cell lines HL-60, U937, and THP-1 to endothelial cells. The CSC stimulated adherence of human monocytes was inhibited (80%) by MAb to CD11b and 50% by Mab to ICAM-1 and ELAM-1. These results suggest that cigarette smoke particulate constituents activate protein kinase C, leading to increased surface expression of adhesive ligand CD11b on peripheral blood monocytes and counter receptor(s) ICAM-1 and ELAM-1 in endothelial cells. The expression of ligand and counter receptor leads to potentiated adherence of monocytes to endothelial cells, an initial event in the pathogenesis of cigarette smoke induced inflammatory response in the vessel wall.

Alkaloids↗

PubMed1991

Glucose induces lipid peroxidation and inactivation of membrane-associated ion-transport enzymes in human erythrocytes in vivo and in vitro.

Erythrocytes of diabetic subjects (non-insulin dependent) were found to have eight- to ten-fold higher levels of endogenously formed thiobarbituric acid reactive malonyldialdehyde (MDA), thirteen-fold higher levels of phospholipid-MDA adduct, 15-20% reduced Na(+)-K(+)-ATPase activity with unchanged Ca+2-ATPase activity, as compared with the erythrocytes from normal healthy individuals. Incubation of normal erythrocytes with elevated concentrations (15-35 mM) of glucose, similar to that present in diabetic plasma, led to the increased lipid peroxidation, phospholipid-MDA adduct formation, reduction of Na(+)-K(+)-ATPase (25-50%) and Ca+2-ATPase (50%) activities. 2-doxy-glucose was 80% as effective as glucose in the lipid peroxidation and lipid adduct formation. However, other sugars, such as fructose, galactose, mannose, fucose, glucosamine and 3-O-methylmannoside, and sucrose, tested at a concentration of 35 mM, resulted in reduced (20-30%) lipid peroxidation without the formation of lipid-MDA adduct. Kinetic studies show that reductions in Na(+)-K(+)-ATPase and Ca+2-ATPase activities precede the lipid peroxidation as the enzyme inactivation occur within 30 min of incubation of erythrocytes with high concentration (15-35 mM) of glucose, while lipid peroxidation product, MDA appears at 4 hr and lipid-MDA adducts at 8 hr. The lipoxygenase pathway inhibitors, 5,8,11-eicosatriynoic acid and Baicalein (5,6,7-trihydroxyflavone), reduced the glucose-induced lipid peroxidation by 30% and MDA-lipid adduct formation by 26%. Indomethacin, a cyclooxygenase pathway inhibitor, had no discernible effect on the lipid peroxidation in erythrocytes. However, the inhibitors of lipid peroxidation, 3-phenylpyrazolidone, metyrapone, and the inhibitors of lipoxygenase pathways did not ablate the glucose-induced reduction of Na(+)-K(+)-ATPase and Ca+2-ATPase activities in erythrocytes. Erythrocytes produce 15-HETE (15-hydroxy-eicosatetraenoic acid), which is augmented by glucose. These results suggest that the formation of lipoxygenase metabolites potentiate the glucose-induced lipid peroxidation and that the inactivation of Na(+)-K(+)-ATPase and Ca+2-ATPase occurs as a result of non-covalent interaction of glucose with these enzymes.

Adenosine Triphosphatases↗

PubMed1990

Heterotypic and homotypic cell-cell adhesion molecules in endothelial cells.

Sickle red blood cells display an abnormal propensity to adhere to cultured bovine aortic endothelial cells when compared to normal red blood cells. The adherence was potentiated three-fold by endothelial cell derived conditioned medium, enriched in multimers of von Willebrand factor. Such adherence was ablated by 80% by either the synthetic peptide (RGDS) or antibody to GPIIb/IIIa, indicating the presence of RGD peptide recognition domain/receptor in either endothelial cells or sickle cells or both. The adherence was also inhibited by 70% by phosphatidylserine, but not by other phospholipids, indicating the presence of putative receptors for this phospholipid in endothelial cells. The labeling of cultured bovine aortic endothelial cells with monoclonal antibodies revealed the localization of MAB D2 to regions of cell-cell contact. The antigen on endothelial cells which cross-reacts with this antibody has a Mr of 130,000. The addition of such an antibody during the plating of endothelial cells disrupted monolayer formation. It appears that a 130-kDa polypeptide antigen in endothelial cells which is recognized by MAB D2, may be a cell-cell adhesion molecule.

Amino Acid Sequence↗

PubMed1988

Topical silver sulphadiazine--a new drug for ocular keratomycosis.

The efficacy of silver sulphadiazine in human keratomycosis has not been evaluated so far. Encouraged by the success of an earlier experimental trial, a prospective, controlled, randomised double masked clinical study was designed to evaluate the efficacy of 1% silver sulphadiazine ophthalmic ointment in 20 eyes of mycotic keratitis. Miconazole 1% was used for comparative evaluation in another 20 eyes. Silver sulphadiazine had a higher success rate (80% vs 55%) than miconazole. It had broad antifungal activity and was found to be effective in fusarium keratitis. Absence of side effects, economy, and its efficacy in deeper and extensive lesions were additional advantages. It is concluded from this study that silver sulphadiazine is a safe and effective broad spectrum antifungal agent which can be used for the treatment of human keratomycosis.

Administration, Topical↗

PubMed1988

Alterations in organization of phospholipids in erythrocytes as factor in adherence to endothelial cells in diabetes mellitus.

Erythrocytes from patients with diabetes mellitus exhibit increased adherence to cultured human vascular endothelial cells. We investigated the alterations in erythrocyte surface characteristics that may contribute to their abnormal adherence. The organization of phospholipids in the lipid bilayer, as determined by phospholipase A2 treatment and chemical labeling with fluorescamine and trinitrobenzene sulfonic acid (TNBS), is altered in erythrocytes from diabetic patients. Specifically, 12-18% of phosphatidylserine in diabetic erythrocytes (n = 25) is accessible to phospholipase A2 hydrolysis and TNBS labeling, compared to none in normal subjects. These results suggest either a loss in lipid asymmetry or in vivo destabilization of erythrocyte membranes in diabetic patients, causing increased accessibility to phospholipase A2 degradation. The dye merocyanine 540 (MC-540), which is sensitive to the packing of lipids in the bilayer of the membrane, revealed more binding and fluorescence in erythrocytes from diabetic patients than in those from normal subjects. On flow cytometric analysis, 64.5 +/- 17.0% red blood cells (RBCs) in diabetic patients, compared to 35.1 +/- 25.9% RBCs in normal subjects, showed positive MC-540 binding, indicating significant (P less than .001) differences in the packing of lipids in the external leaflet of the bilayer. The results of our study suggest that a loss of lipid asymmetry and/or less ordered packing in the outer leaflet of the diabetic erythrocyte membrane may be responsible for the increased propensity of erythrocytes to adhere to vascular endothelium.

Adult↗