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Biomedical subjects

V Kumar

Publications and source records attributed to V Kumar.

At least 793 records · Page 44Linked to original sources
PubMed1981

Studies on natural killer (NK) cells. II. Serologic evidence for heterogeneity of murine NK cells.

NK cells are divided into 2 subclasses on the basis of cell surface antigens: NKA cells, which preferentially lyse lymphoma cells and which are readily destroyed by treatment with anti-H-2, rabbit anti-mouse, or anti-NK specific antibodies in the presence of C; and NKB cells, which preferentially lyse nonlymphoma tumor cells and which are resistant to anti-NK specific antibodies, partially sensitive to anti-H-2 specific antibodies, and only fully sensitive to rabbit anti-mouse serum and C. Thus, suspensions of spleen cells that were treated with anti-NK-1.2 antibodies and C lost virtually all lytic activity for 6 lymphoma cell lines, whereas lytic activity for 2 nonlymphoma cell lines remained largely intact. It must be noted, however, that unlike NK-1.2 expression, target cell preference is not an absolute indicator of NK cell subclass. Cytotoxic T cells were readily distinguished from NKA and NKB cells on the basis of their sensitivity to monoclonal anti-Thy-1.2 antibodies and resistance to anti-NK-1.2 antiserum and C.

Animals↗
PubMed1981

Serodiagnosis of Taenia saginata cysticercosis in experimentally and naturally infected cattle by enzyme linked immunosorbent assay.

The sensitivity and specificity of enzyme linked immunosorbent assay (ELISA) for the diagnosis of Taenia saginata cysticercosis was studied among laboratory reared experimentally infected calves and conventionally raised naturally infected cattle by using a T crassiceps metacestode antigen. The intensity of the metacestode burden in experimentally infected animals had a direct effect on the first appreciable rise in the spectrophotometric extinction values and also on the progressive elevation of these values during the later stages of infection. The animals harbouring less than 100 metacestodes were the most difficult to detect by ELISA. Serum from sheep infected with Cysticercus tenuicollis showed cross-reaction. Among the naturally infected cattle the sensitivity of ELISA was poor; only 37.5 per cent of the 24 proven cases could be diagnosed. One of the nine cattle harbouring natural infection of Fasciola hepatica showed cross-reaction. Of the 69 animals 4.3 per cent showed false positive reactions.

Animals↗
PubMed1981

Immunofluorescence findings in rapid whitening of scalp hair.

Rapid whitening of scalp hair developed during a three-month period along with a diffuse, subtotal alopecia in a patient. Immunofluorescence microscopy of biopsy material showed prominent deposits of IgG and IgM in a granular pattern in the epithelium of the lower portions of hair follicles. Some return of the color and amount of scalp hair occurred within a year, but occasional bouts of hair loss continued to occur. It is theorized that the rapid graying was caused by a selective loss of pigmented hair, which was perhaps caused by an immunologic mechanism. Some of the findings suggest that the cause of this patient's loss of hair color may be different from those of patients who have been previously described as having rapid whitening of scalp hair because of alopecia areata or vitiligo.

Depression↗
PubMed1980

Monoclonal antibodies to Escherichia coli 50S ribosomes.

Hybridoma cell lines that produce monoclonal antibodies directed against 50S Ribosomal proteins have been isolated. Spleen cells (from BALB/c mice immunized with 50S ribosomal subunits extracted from Escherichia coli) were fused to mouse myeloma cell line SP2/O-Ag 14. The initial screening for antibody producing hybridomas was carried out by a double antibody sandwich method; hybridomas were subsequently cloned in soft agar. Antibodies were characterized by their specific binding to individual 50S ribsomal proteins separated on phosphocellulose columns and in two-dimensional polyacrylamide gels. The assignments were confirmed with purified single ribosomal proteins. Of four clones analyzed thus far, two are identical with specificity for r-protein L5. The other clones produce two different antibodies directed against r-protein L20. Each monoclonal antibody formed ribosome dimers visualizable in the electron microscope. Dimers could be reacted with a different second antibody to form chains containing 8 or more ribosomes, which may be useful for structural studies.

Animals↗
PubMed1980

A case of cicatricial pemphigoid or cicatricial linear IgA bullous dermatosis.

A case has been described with clinical features of cicatricial pemphigoid, but immunofluorescent (IF) biopsy findings are suggestive of linear IgA bullous dermatosis (LABD), i.e., the presence of IgA deposits with a linear pattern at the basement membrane zone. The patient failed to respond to sulfones and gave a limited response to corticosteroid. These findings suggest that therapy of the type found to be effective in cutaneous forms of LABD, i.e., combinations of low doses of sulfones and corticosteroids, may be indicated in such cases.

Adrenal Cortex Hormones↗
PubMed1980

Aminoglycoside antibiotics. 3. Epimino derivatives of neamine, ribostamycin, and kanamycin B.

2',3'-Epimino analogues of neamine, ribostamycin, and kanamycin B possessing little or no intrinsic antimicrobial activity were designed to enhance the activity of kanamycin A against bacterial strains that elaborate aminoglycoside 3'-phosphotransferases. Routes were devised for their synthesis from the parent antibiotics and the 2'',3''-epimino analogue of kanamycin B also was prepared. None of these analogues was active against phosphotransferase-producing bacteria, although the kanamycin B derivatives showed very weak activity against nonresistant strains. At 8 and 32 microgram/mL, the 2',3'-epimino analogue of neamine produced a small synergistic effect on the activity of kanamycin A against a strain of Escherichia coli that produces aminoglycoside 3'-phosphotransferase II. The N3-(carbobenzyloxy) derivative of this analogue produced a small effect against the same strain, and it, as well as the 2'',3''-epimino analogue of kanamycin B, slightly enhanced the activity of kanamycin A against a strain of Proteus rettgeri that elaborates a similar enzyme.

Anti-Bacterial Agents↗
PubMed1980

Preparation and antitumor activity of olivomycin A analogues.

Novel analogues of olivomycin A were prepared by selective reactions involving the carbonyl and hydroxyl groups of the aglycon moiety. Electrophilic substitution of the aglycon also was successful. Of 11 analogues, all but two were active in the P-388 murine leukemia assay. One compound, the 2'-methoxime, showed superior activity to olivomycin A based on its wider dose range and greater potency. The methyl imine and the 8-O-methyl ether were equal to olivomycin A in potency and efficacy. Most of the other analogues were slightly less potent or effective.

Animals↗
PubMed1980

8-Hydroxyanthracyclinones from epsilon-rhodomycinone.

epsilon-Rhodomycinone was converted into 8,9-dehydro-zeta-rhodomycinone, which gave a cis diol with osmium tetroxide and a pair of epimeric epoxides with m-chloroperbenzoic acid. Acid-catalyzed opening of the epoxides gave the corresponding trans diols. In contrast, acid treatment of the trimethyl ethers of these epoxides gave predominantly a lactone and an eta-rhodomycinone derivative, with only small amounts of the diols. None of the new rhodomycinones were active against Bacillus subtilis, but 8,9-dehydro-zeta-rhodomycinone was active in the induction of lytic phage in Escherichia coli.

Anthracyclines↗