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Biomedical subjects

M Krishnan

Publications and source records attributed to M Krishnan.

At least 37 records · Page 2Linked to original sources
PubMed1989

Differential effect of type I and type II diabetes mellitus on serum ampicillin levels.

Ampicillin elimination was studied in 10 poorly controlled, 6 well controlled type I and 14 poorly controlled type II diabetic patients. Two groups of age-matched healthy volunteers served as controls. After oral administration of ampicillin (500 mg), the poorly controlled type I diabetics had significantly lower serum concentration of the drug when compared to their corresponding healthy controls. The elimination half-life (t1/2) remained unaltered. Their creatinine clearance rate and urinary excretion of the drug were significantly reduced. There was no difference in these parameters between well controlled diabetics and healthy volunteers. The bioavailability data calculated from the urinary recovery of the drug, after oral and i.v. administration, suggested reduced oral absorption in poorly controlled type I diabetic patients. Ampicillin kinetics data of poorly controlled type II diabetic patients were not significantly different from that of the control group. Serum ampicillin levels and urinary excretion of the drug were similar in these groups. It is concluded that serum ampicillin level may be lower in poorly controlled type I diabetics which may be due to reduced absorption of the orally administered drug.

Adult↗
PubMed1989

Effect of type II diabetes mellitus on theophylline elimination.

Theophylline elimination was studied in poorly-controlled and well-controlled type II diabetic patients, seven in each group. Eight healthy volunteers served as a control group. After a single oral dose of theophylline (200 mg) the drug concentration was measured in plasma, collected at different time intervals, using a high pressure liquid chromatography method. The poorly-controlled diabetics had significantly longer elimination half-life (t1/2) due to increased apparent volume of distribution (V) of the drug when compared to well-controlled diabetics. Their clearance rate (Cl) remained unaltered. There was no significant difference in these parameters between healthy volunteers and diabetic patients, although poorly-controlled diabetics had a tendency for higher t1/2 and V. It is concluded that theophylline clearance is unaltered in type II diabetic patients.

Adult↗
PubMed1988

Heat shock response of the chloroplast genome in Vigna sinensis.

The light-dependent protein synthesis occurring in chloroplasts isolated from the leaves of 7-day-old Vigna sinensis responded to heat shock with the induction of a set of four heat shock proteins (HSPs). The synthesis of these four HSPs at the elevated temperature was transcriptionally regulated, and all of them were found to be thylakoid membrane-bound. The synthesis of these chloroplast-coded HSPs was also observed in etioplasts during protein synthesis at the elevated temperatures with the exogenously added ATP. The in vivo induction of these plastid-coded HSPs was observed only in the leaves subjected to gradual increase in temperature but not in leaves subjected to rapid heat shock. Further, the in vitro synthesis of these plastid-coded HSPs was seen only in chloroplasts isolated from the control or from leaves subjected to gradual increase in temperature and not in chloroplasts isolated from leaves subjected to rapid heat shock. Taken together these observations suggest that in V. sinensis, the plastid genome contains a definite heat shock response and the in vivo expression of this response corresponds to the gradual rise in temperature normally occurring under field conditions.

Chloroplasts↗
PubMed1988

Antibodies to liver/kidney microsome1 in chronic active hepatitis recognize specific forms of hepatic cytochrome P-450.

Anti-liver/kidney microsome1-positive sera from children with chronic active hepatitis were studied in an effort to identify the microsomal antigens selected during induction and progression of this autoimmune disease. Immunoblot analysis of sodium dodecyl sulfate gel-resolved microsomal proteins from human and rat liver using anti-liver/kidney microsome1-positive sera revealed a single polypeptide of 48 kilodaltons (human microsomes) or 50 kilodaltons (rat microsomes). Levels of the 50-kilodalton rat microsomal polypeptide were suppressed in vivo by several drugs known to modulate expression of individual forms (enzymes) of hepatic cytochrome P-450, with the largest decrease effected by phenobarbital. Dot blot analysis using a panel of 10 electrophoretically homogeneous rat liver cytochrome P-450 forms under nondenaturing conditions established that the two methylcholanthrene-inducible forms, P-450 BNF-B and P-450 ISF-G (P-450 gene subfamily IA), are selectively recognized by the anti-liver/kidney microsome1 antibodies. These findings demonstrate that sera associated with autoimmune (anti-liver/kidney microsome1) chronic active hepatitis are specifically reactive with select rat hepatic P-450 forms and suggest that these autoantibodies may be principally directed against one or more constitutive forms of the corresponding human liver cytochromes.

Autoantibodies↗
PubMed1986

An efficient and prolonged in vitro translational system from isolated cucumber etioplasts.

Etioplasts were isolated from dark grown cucumber cotyledons pretreated with kinetin and gibberellic acid. When incubated in a cofactor enriched medium these etioplasts incorporated [35S] methionine into a hot trichloroacetic acid-insoluble fraction; this incorporation was linear for 8 h of incubation and was inhibited by chloramphenicol but not by cycloheximide. Over the same time period, the etioplasts showed continued linear synthesis of the chlorophyll precursors protochlorophyllide, Mg-protoporphyrin and protoporphyrin IX. Analysis of products of in vitro protein synthesis by etioplasts and cotyledons showed the thylakoid membrane polypeptide profiles to be identical. Continued incorporation of [35S] methionine into the large subunit of ribulose bisphosphate carboxylase/oxygenase (RuBisCO) for 8 h has been confirmed further by immunoprecipitation with anti-spinach RuBisCO. This competent in vitro translation system should be useful for future studies of chloroplast protein synthesis and gene expression.

Amino Acids↗
PubMed1984

Radioisotopic evidence for the polypeptides associated with photosystem II.

Direct radioisotopic evidence for the polypeptides associated with oxygen evolution in a non-destructive approach by comparing the polypeptides of photosystem II (PS II) particles in etioplasts that lack O2 evolution with that of chloroplasts that exhibit high rates of oxygen evolution is reported. Polypeptide analysis by coomassie blue staining revealed that 32, 23 and 15 kDa proteins were absent in etioplast particles but developed in chloroplast PS II particles after illumination. However, a strikingly different picture was obtained when labelled polypeptides were analyzed from the fluorograph. While the new proteins identified by coomassie blue staining were also labelled, intensely labelled major polypeptides of molecular range 40, 41, 43 kD and minor polypeptides of molecular range 47, 48, 51 kD were observed in chloroplast PS II particles but not in etioplasts or etioplast particles; these labelled polypeptides were so prominent that they could be identified even in thylakoid membranes.

Chlorophyll↗