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Biomedical subjects

V Kumar

Publications and source records attributed to V Kumar.

At least 775 records · Page 43Linked to original sources
PubMed1982

A preliminary report on Meriones unguiculatus as an experimental host for Taenia saginata metacestodes.

Jirds (Meriones unguiculatus) were treated with dexamethasone and inoculated subcutaneously with 100-300 oncospheres of Taenia saginata. Ten of the jirds received 0.5 mg of the drug per animal twice weekly during the first month after inoculation and then once a week until necropsy and four of these became infected. Up to 20 viable metacestodes were recovered in the subcutaneous tissue at the site of inoculation three months after infection.

Animals↗
PubMed1981

2,3-Dehydro-4-epi-N-acetylneuraminic acid; a neuraminidase inhibitor.

Treatment of N-acetylneuraminic acid methyl ester with sulfuric acid and acetic anhydride at 50 degrees followed by deacetylation gave 2,3-dehydro-2-deoxy-N-acetylneuraminic acid methyl ester and methyl 5-acetamido-2,6-anhydro-2,3,5-trideoxy-D-glycero-D-talo-non-2-enonate (2,3-dehydro-4-epi-NeuAc methyl ester) in equal yields (approximately 40% each). The structure of the latter was ascertained primarily from analysis of its mass spectrum and 1H- and 13C-nuclear magnetic resonance spectra. The relative proportions of these two glycals in the foregoing reaction was dependent on temperature, as at 0 degrees, the yield of 2,3-dehydro-4-epi-NeuAc was markedly diminished. A minor by-product of this acetylation reaction was 2-methyl-(methyl 7,8,9-tri-O-acetyl-2,6-anhydro-2,3,5-trideoxy-D-glycero-D-talo-non-2-enonate)-[ 4,5-d]-2-oxazoline. Based upon this finding and additional interconversion experiments, a mechanism involving the intermediacy of the latter oxazoline to account for the epimerization is proposed. These glycals and their methyl esters are competitive inhibitors of Arthrobacter sialophilus, neuraminidase, suggesting that the 4-hydroxyl group must be equatorially oriented for maximal enzyme inhibition.

Arthrobacter↗
PubMed1981

Heterogeneity of natural killer cells in the mouse.

Mice were treated with the bone-seeking isotope, 89Sr, cyclophosphamide, and short-term lethal irradiation in vivo, and murine spleen cells are treated with anti-Nk-1.2 plus complement (C) in vitro. Fresh spleen cell suspensions from the above groups and from beige and neonatal mice were subsequently tested for natural killer (NK) cell activity against a panel of lymphoid and nonlymphoid tumor cell target. NK cell reactivities against YAC-1, MPC-11, and Cl.18 tumors were markedly and consistently reduced in (a) mice treated with 89Sr, (b) spleen cells treated with anti-Nk-1.2 plus C, and (c) C57BL/6 bg/bg mice. In contrast, NK activities against FLD-3 and WEHI-164.1 tumors were usually normal in mice treated with 89Sr, in beige mutant mice, and in spleen cells after treatment with anti-Nk-1.2 antibody and C. It appears, therefore, that two major groups of NK cells exist in fresh mouse spleen cells suspensions. NK-A cells are marrow dependent, Nk antigen positive, and deficient in beige mice; these lyse YAC-1, MPC-11, and Cl.18 tumors. NK-B cells, which are responsible for the lysis of WEHI-164.1 and FLD-3, are Nk antigen negative, marrow independent, and unaffected by the bg/bg mutation. Other features of NK-B cells, suggest that these NK cells, although they share the characteristics mentioned above, differ among themselves especially with respect to age of maturation and susceptibility to cyclophosphamide and total body irradiation. The NK-B group may therefore induce subsets that remain to be defined.

Aging↗
PubMed1981

Isolation of fraction no. 10 from Taenia saginata and evaluation of its specificity for the diagnosis of bovine cysticercosis.

In an attempt to prove the specificity of the crude Taenia saginata antigen for the immunodiagnosis of bovine cysticercosis, a major and highly immunogenic fraction (F10), responsible for the formation of the typical "long band" reaction in immunoelectrophoresis, has been isolated from T. saginata proglottides by immunoaffinity chromatography. The immunoabsorbent was prepared by coupling a specifically raised hyperimmune serum (HIS) anti-F10 to Sepharose 4B. The purity of the isolated F10 was demonstrated by immunoprecipitation reactions. The HIS anti-F10, however, cross-reacted with several larval and adult Taenia spp. Consequently, F10 showed cross-reactions with the sera of animals infected with hydatid cysts or larval T. hydatigena. F10 also reacted with HIS anti-F5 (Echinococcus granulosus) but was shown to be non-identical with the well known F5 of E. granulosus. These data prove that F10 of T. saginata was not species-specific but showed a group specificity for the taeniid family - a situation analogous to F5 of E. granulosus.

Animals↗
PubMed1981

Sheep as an experimental model of Taenia saginata cysticercosis.

Taenia saginata cysticercosis was experimentally produced in 4 Soay sheep, 1 four-horned sheep and 1 Texel sheep by oral administration of eggs of the parasite. Some of these sheep were given dexamethasone therapy. The evolution of T. saginata cysticercosis in this host is characterised by a rapid immune reaction so that by 6 weeks after infection almost all the cysts were dead. There were indications that the dexamethasone therapy may have assisted establishment of the infection and to some extent, postponed the process of degeneration.

Animals↗
PubMed1981

Hybrid resistance to EL-4 lymphoma cells. II. Association between loss of hybrid resistance and detection of suppressor cells after treatment of mice with 89Sr.

(C57BL/6 X DBA/2)F1 hybrid (B6D2F1) mice resist the growth of parental-strain (B6) EL-4 lymphoma cells inoculated intraperitoneally; that is, B6D2F1 mice survive longer than B6 mice and do not develop ascites. As compared with B6 mice, B6D2F1 mice have higher levels of natural killer (NK) activity against 51Cr-labelled EL-4 cells in their lymphoid organs. B6D2F1 mice treated with 89Sr lose NK activity for certain lymphoma cell targets, e.g. YAC-1, but NK(EL-4) function is usually intact. However, 89Sr-treated mice had lost hybrid resistance to EL-4 cells in vivo, as determined by survival by irradiated or unirradiated EL-4 cells, Corynebacterium parvum, or polyinosinic:polycytidylic acid (pI:pC) in spleens of normal B6D2F1 mice, but NK(EL-4) activity was depressed within 3 days by such treatment in B6D2F1 mice previously injected with 89Sr. Suppressor cells for NK(EL-4) but not for NK(YAC-1) effectors were easily detected in spleens of 89Sr-treated mice "challenged' with C. parvum. Thus, agents capable of stimulating NK cell function in normal mice may lead to suppression of that activity in mice depleted of marrow-dependent cell function by 89Sr. Spleen cells of 89Sr-treated B6D2F1 mice were also unable to generate anti-EL-4 cytotoxic T lymphocytes in a cell-mediated lympholysis system; this defect appeared also to be mediated by suppressor cells. Lymphoid cells depleted by 89Sr-induced marrow aplasia may have two functions in host defences against tumours (especially lymphomas): they may lyse tumour cells directly and they may "down-regulate' suppressor cells capable of inhibiting other "natural' or "induced' immune functions.

Animals↗
PubMed1981

Study of the efficacy of compound Go.9333 (Ciba-Geigy) in hookworm infestation.

50 cases with hookworm infestation were studied to find out the species of the parasite, 25 of them were included for a double-blind trial of compound Go.9333 (Ciba-Geigy)/placebo. Results of the study revealed predominance of Necator americanus (96%) in and around Pondicherry, South India. Compound Go.9333 was found to very effective in the treatment of hookworm infestation. Side effects were minor and were not of much significance. The drug was well accepted and tolerated by most of the cases. On the basis of the present study, compound Go.9333 can be recommended for the treatment of hookworm infestation.

Aniline Compounds↗