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Biomedical subjects

A S Giasuddin

Publications and source records attributed to A S Giasuddin.

7 recordsLinked to original sources
PubMed1985

Comparative immunogenicity and protective effect against dental caries of a low (3800) and a high (185,000) molecular weight protein in rhesus monkeys (Macaca mulatta).

The immunogenicity and protective effect of two peptides derived from the human oral bacterium Streptococcus mutans (serotype c) was examined. Furthermore, the effect of immunization was examined in monkeys previously given fluoride in their diet and which had developed a low incidence of dental caries when offered a human type of diet containing about 15 per cent sucrose. The 3800 peptide streptococcal antigen (SA) has two major antigenic determinants, similar to those in the 185,000 SA I/II. Immunization with 10 (or 1) micrograms of the 3800 SA, made up in an aluminium-hydroxide adjuvant, induced a consistent increase in serum IgG, IgM and IgA antibodies to SA I/II throughout the period of investigation. Salivary-IgA antibodies were only slightly raised. Sequential examination up to 76 weeks showed a significantly lower incidence of dental caries and a lower proportion of Strep. mutans in the immunized compared with sham-immunized, control monkeys. Thus immunization with the 185,000 or 3800 SA can almost completely prevent dental caries in rhesus monkeys which otherwise develop a low incidence of caries.

Animals↗
PubMed1975

The dependence on vitamin E and selenium of drug demethylation in rat liver microsomal fractions.

1. The effects of vitamin E deficiency, and of vitamin E and selenium deficiency, on rat liver microsomal aminopyrine demethylase activity were investigated. It was found that, over a wide range of substrate concentrations, the enzyme activity in preparations from deficient animals was significantly lower than that in controls. 2. Addition of antioxidants in vitro, either to the homogenization or to the assay media, was without significant effect on the depressed enzyme activity. Castration and alteration in dietary protein concentration were also without effect. The rate of oxidation of NADPH was however, lower in preparations from deficient animals. 3. Lineweaver-Burk plots of the reciprocal of enzyme activity and substrate concentration showed a higher Km value in preparations from vitamin E-deficient animals, irrespective of whether selenium was present; the Vmax. was unaffected. These parameters were unchanged when antioxidants were added in vitro. Induction with phenobarbitone and 3-methylcholanthrene showed large changes in Km value which, for preparations from vitamin E-deficient animals, was higher than that for corresponding controls. 4. Examination of the synergism between NADH and NADPH as donors of reducing equivalents for aminopyrine demethylation showed that vitamin E and selenium were only minimally involved in the phenomenon. However, both the initial rate and the extent of demethylation were significantly lower in vitamin E- and selenium-deficient preparations and both nutrients were required for the restoration of full activity. 5. The significance of these results is discussed in the light of our working hypothesis.

Aminopyrine↗