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Biomedical subjects

S Bhat

Publications and source records attributed to S Bhat.

At least 55 records · Page 3Linked to original sources
PubMed1992

Galactose to ceramide linkage is essential for the binding of a polyclonal antibody to galactosyl ceramide.

Characterization of a polyclonal antibody to galactosyl ceramide (Gal-Cer) which inhibits the internalization and infection of HIV-1 in neural cell lines was carried out. Polyclonal antibody to Gal-Cer was produced by injecting rabbits with Gal-Cer liposomes. The specificity of anti-Gal-Cer binding was studied by high performance thin layer chromatography (HPTLC)-based immunoassay. Using natural and semisynthetic lipids, the specificity of anti-Gal-Cer interaction was studied. The antibody bound to Gal-Cer and its derivatives. The antibody did not bind to glucosyl ceramide or lactosyl ceramide. Glucosyl ceramide differs from Gal-Cer by a hydroxyl group at the fourth carbon and in lactosyl ceramide galactose is linked to ceramide by an intervening glucose molecule. This indicates that D-galactose linked to ceramide is essential for binding. Removal of fatty acid from Gal-Cer, as seen with N-palmitoyl- and N-oleoyl Gal-Cer, had no effect on the binding. It appears that the third carbon of Gal-Cer is not involved in the binding. This is supported by the binding of anti-Gal-Cer to sulfatide or GM4 in which sulfate or sialic acid are added at the third carbon of Gal-Cer, respectively.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Primary disseminated fusarial infection.

Among the fungal pathogens the species Fusariam solani causing systemic infection is very rare and generally causes systemic infection only in an immuno-compromised host. We report a systemic infection caused by F. solani in a non-immunocompromised adult male, to our knowledge the first such case report.

Adult↗
PubMed1991

Galactosyl ceramide or a derivative is an essential component of the neural receptor for human immunodeficiency virus type 1 envelope glycoprotein gp120.

This report demonstrates that galactosyl ceramide (GalCer) or a molecule derived from it may serve as an alternative receptor for human immunodeficiency virus in the nervous system. Recombinant gp120, an envelope glycoprotein of human immunodeficiency virus type 1, specifically binds to GalCer and its derivatives. This specificity was studied by inhibiting binding of radioiodinated gp120 to GalCer with antibodies to GalCer, antibodies to gp120, and an excess of unlabeled gp120. Binding activity was also removed by absorbing gp120 with liposomes containing GalCer. In addition, studies using natural and semisynthetic lipids indicate that the linkage between galactose and ceramide is essential for binding. The significance of an alternative receptor for human immunodeficiency virus in the nervous system is discussed.

Binding Sites↗
PubMed1991

Inhibition of entry of HIV-1 in neural cell lines by antibodies against galactosyl ceramide.

Although the CD4 molecule is the principal cellular receptor for the human immunodeficiency virus (HIV), several CD4-negative cell lines are susceptible to infection with one or more HIV strains. These findings indicate that there are alternate modes of viral entry, perhaps involving one or more receptor molecules. Antibodies against galactosyl ceramide (galactocerebroside, or GalC) inhibited viral internalization and infection in two CD4-negative cell lines derived from the nervous system: U373-MG and SK-N-MC. Furthermore, recombinant HIV surface glycoprotein gp120 bound to GalC but not to other glycolipids. These results suggest a role for GalC or a highly related molecule in HIV entry into neural cells.

Antibodies↗
PubMed1990

Expression of neural cell adhesion molecule in dysmyelinating mutants.

The possible role of neural cell adhesion molecule (NCAM) in myelination was studied in the dysmyelinating mouse mutants jimpy and shiverer, by characterizing the expression of the different molecular forms of brain NCAM as a function of age. In jimpy, the expression of NCAM-120 (120,000-Da NCAM) was low and in shiverer both NCAM-120 and NCAM-180 (180,000-Da NCAM) were reduced when compared to controls. In both jimpy and shiverer there was no significant change in the phospholipase C-sensitive NCAM-120. These data further support the possibility that NCAM may be involved in myelination.

Animals↗
PubMed1990

Sonographic pseudokidney after nephrectomy.

When interpreting renal sonograms, one should be aware of the possibility of mistaking fat and scarring in the renal fossa for a normal kidney in a patient with a history of prior nephrectomy. When in doubt, the ultrasound findings should be confirmed with a CT scan.

Adipose Tissue↗
PubMed1990

Adhesion of cellulolytic ruminal bacteria to barley straw.

Adhesion of the cellulolytic ruminal bacteria Ruminococcus flavefaciens and Fibrobacter succinogenes to barley straw was measured by incubating bacterial suspensions with hammer-milled straw for 30 min, filtering the mixtures through sintered glass filters, and measuring the optical densities of the filtrates. Maximum adhesion of both species occurred at pH 6.0 and during mid- to late-exponential phase. Adhesion was saturable at 33 and 23 mg (dry weight) g of straw for R. flavefaciens and F. succinogenes, respectively. Methyl cellulose and carboxymethyl cellulose inhibited adhesion by 24 to 33%. Competition between species was determined by measuring characteristic cell-associated enzyme activities in filtrates of mixtures incubated with straw; p-nitrophenyl-beta-d-lactopyranoside hydrolysis was used as a marker for F. succinogenes, while either beta-xylosidase or carboxymethyl cellulase was used for R. flavefaciens, depending on the other species present. R. flavefaciens had no influence on F. succinogenes adhesion, and F. succinogenes had only a minor (<20%) effect on R. flavefaciens adhesion. The noncellulolytic ruminal bacteria Bacteroides ruminicola and Selenomonas ruminantium had no influence on adhesion of either cellulolytic species, although these organisms also adhered to the straw. We concluded that R. flavefaciens and F. succinogenes have separate, specific adhesion sites on barley straw that are not obscured by competition with non-cellulolytic species.

Journal Article↗
PubMed1990

Hydrophobic photolabeling in membranes: the human erythrocyte glucose transporter.

Human erythrocyte membranes were labeled with a hydrophobic photoactivable reagent, 2-[3H]Diazofluorene. Electrophoretic analysis of the protein fraction showed that several membrane spanning proteins like Band 3 (the anion transporter), Band 4.5 (the glucose transporter), and the sialoglycoproteins PAS 1, 2, and 3 have been labeled. To isolate the diazofluorene-labeled glucose transporter, the membrane preparation was solubilized with Triton X-100 and passed through a DEAE-cellulose column. The flow-through fraction was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Radioactive analysis of the gel indicated that besides the Band 4.5, two more proteins corresponding to the Band 3 and Band 6 regions also coelute with the glucose transporter in the flow-through fraction. On the other hand, use of n-octyl glucoside gave a relatively better preparation. The 2-[3H]DAF-labeled glucose transporter isolated by the latter method on tryptic digestion indicated that the Mr 18,000 fragment corresponding to the C-terminal transmembrane fragment is labeled.

Affinity Labels↗
PubMed1989

Hypertrophic osteoarthropathy associated with Pneumocystis carinii pneumonia in AIDS.

Hypertrophic osteoarthropathy (HOA) is a systemic disorder primarily affecting the bones, joints, and soft tissues and developing in association with another disease process. Acute pyogenic pulmonary processes (empyema, lung abscess) are occasionally accompanied by transient HOA, but reversible HOA has not previously been reported in the setting of PCP in AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Occular loiasis in a Zambian woman.

Asymptomatic infection with Loa loa, an eye worm, is reported in a 32-year old Zambian woman. The patient revealed up to 28% eosinophilia but microfileraemia was not noticed. One gravid female parasite 56 X 0.56 mm, extracted from lower lid of left eye of the patient, is described. Treatment with diethylcarbamazine (DEC) extended over three weeks was successful against another parasite in tissues.

Adult↗
PubMed1989

Reversible pulmonary uptake and hypertrophic pulmonary osteoarthropathic distribution of technetium-99m methylene diphosphonate in a case of Pneumocystis carinii pneumonia.

Diffuse pulmonary deposition of [99mTc]methylene diphosphonate (MDP) as well as abnormalities characteristic of hypertrophic pulmonary osteoarthropathy have been observed in a patient with Pneumocystis carinii pneumonia (PCP). The findings of the bone scan together with those in the corresponding scintigraphy, and roentgenograms of the chest and skeletal structures are presented. Parallel reversal of [67Ga]citrate and [99mTc]MDP pulmonary uptake with specific treatment for and clinical resolution of PCP implies a causal relationship.

Adult↗
PubMed1988

NCAM-180, the largest component of the neural cell adhesion molecule, is reduced in dysmyelinating quaking mutant mouse brain.

To explore the role of the neural cell adhesion molecule (NCAM) in myelination and remyelination, we studied the developmental expression of various molecular forms of NCAM in dysmyelinating quaking mouse brain as compared with normal mouse brain. Normal mouse brain expressed the several molecular forms differentially during development. Quaking showed a marked reduction in the expression of NCAM-180, which represents the largest component of NCAM, in comparison with normal brain. This suggests that the defective myelin compaction in the quaking mutation may be the result of a deficiency of NCAM-180.

Age Factors↗
PubMed1988

Induction of glial cell MHC antigen expression in neurotropic coronavirus infections. Characterization of the H-2-inducing soluble factor elaborated by infected brain cells.

Neurotropic coronavirus (mouse hepatitis virus strain A59) infection induces major histocompatibility complex class I (H-2) surface antigens on oligodendrocytes and astrocytes, cells that do not normally express detectable MHC antigens on their surface. The induction on MHC antigen expression potentially allows immunocytes to interact with infected glial cells and may play a critical role in the development of virus-induced, immune-mediated demyelination in the central nervous system, a possible model of human multiple sclerosis. In this study, we characterized the soluble factor involved in MHC antigen induction, quantitated induction of MHC antigens, and analyzed the central nervous system cell type involved in the production of the factor. The H-2-inducing factor, most likely produced by astrocytes, was found to be nondialyzable, heat- and trypsin-sensitive, but resistant to treatment at pH 2.0. The m.w. of the factor was estimated as 50 to 100 kDa. Studies on fractionation by ultrafiltration and sucrose density gradient along with antibody-blocking experiments indicate that the factor is not interferon or virus particles.

Animals↗
PubMed1988

Developmental expression of neural cell adhesion molecules of oligodendrocytes in vivo and in culture.

Previously, we have shown that oligodendrocyte adhesion molecules are related to the 120,000-Mr neural cell adhesion molecule (NCAM-120). In this report, we present further evidence that the oligodendrocyte adhesion molecule is NCAM-120. Studies on the expression of NCAM-120 and other molecular forms of NCAM in vivo in rat brain, in vitro in primary mixed cultures, and in cultures enriched for oligodendrocytes are described. Western blot analysis of rat brain using anti-NCAM showed that NCAM-120 first appears at postnatal day 7 and increases in quantity thereafter, coincident with the development of oligodendrocytes in vivo and comparable to the expression of myelin basic protein. Purified oligodendrocytes from 4-week-old rat brains expressed only NCAM-120. Quantitation of various forms of NCAMs in rat brain showed marked age-related differences in the expression of three molecular forms of NCAM. Immunofluorescence analysis showed that oligodendrocytes, at all ages tested, expressed NCAM, but in older oligodendrocytes, the intensity of staining was less. Western blot analysis of oligodendrocyte-enriched cultures showed that from day 1 after isolation (12 days of age) through day 7 after isolation (18 days of age) only NCAM-120 is seen. A possible role for NCAM in myelination and remyelination is discussed.

Aging↗
PubMed1988

Neuroblastoma cell-oligodendrocyte interaction is mediated by neural cell adhesion molecules.

The role of neural cell adhesion molecule (NCAM) in the interaction between neurons and oligodendrocytes was studied using N2A neuroblastoma cells, which express only the 180,000 Mr NCAM and rat oligodendrocytes which express only 120,000 Mr NCAM. Oligodendrocytes bound to neuroblastoma cells, and the binding was inhibited by anti-NCAM, suggesting that NCAM is involved in oligodendrocyte-neuron interaction. The possible role of NCAM in myelination and remyelination is discussed.

Antigens, Surface↗
PubMed1987

C6 glioma cells express modified neural-cell adhesion molecule-like glycoproteins.

We have studied the expression of neural-cell adhesion molecule (N-CAM)-like glycoproteins in a C6 glioma cell line. We found that: (a) C6 cells express N-CAM-like proteins on the cell surface, (b) the N-CAM-like proteins in C6 cells have apparent molecular weights of 130,000 and 150,000 kDa which are not seen in rodent brain and (c) deglycosylation of C6 N-CAMs suggest that the modifications are both in the carbohydrate and protein parts of the N-CAM. The expression of modified N-CAM glycoproteins is of interest in relation to the regulation of N-CAM expression.

Animals↗