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Biomedical subjects

S Iyengar

Publications and source records attributed to S Iyengar.

118 records · Page 7Linked to original sources
PubMed1981

Glucose-6-phosphate dehydrogenase and NADP-linked malate dehydrogenase during posthatching development of brain of altricial birds.

Glucose-6-phosphate dehydrogenase and NADP-linked malate dehydrogenase were studied in different areas of the brain of three altricial birds during posthatching development. The birds were pigeon and swift, having a posthatching nestling period of 30 days; and sparrow, having a posthatching nestling period of 14 days. The activity of the two enzymes was high during development. G-6-PD activity may be high because of the need for pentoses in the early part of development and the need for reducing equivalents (NADPH2) for synthesis of lipids and other compounds in the later stages of development. Malic enzyme activity also seems to be high because of the need for reducing equivalents. The activity of malic enzyme was found to be higher than that of G-6-PD.

Animals↗
PubMed1981

Changes in lipid content during the post-hatching development of the brain of altricial birds.

The post-hatching development of the brain was studied in three altricial birds (those whose development is completed after hatching), namely, the domestic pigeon, house swift and house sparrow, to assess the state of maturity of the brain at the time that the fledglings leave the nest. Maturity is related to the process of myelination and, therefore, Sudan Black was chosen as it is a sensitive indicator of myelin lipids. On hatching, it was found that sudanophilia was very low in all three birds, indicating a lack of maturation. However, between 15 to 25 days in the pigeon and swift and between 8 and 14 days in the sparrow, there was a steady increase in Sudan Black staining. By the time the birds left their nests, the staining was similar to that of adults, thus indicating that the process of myelination was complete and that the brains were mature.

Animals↗
PubMed1981

Monoamine oxidase in brain maturation: a histochemical study during posthatching development in altricial birds.

Monoamine oxidase was studied histochemically in the brain of three altricial birds, domestic pigeon house swift and house sparrow, during posthatching development. It was found that there was a steady increase in the activity of the enzyme in all areas of the brain of the three birds. The medulla and thalamus showed adult pattern of maturation by 15-20 days in sparrow while the optic lobes and cerebellum did so by 25 days in the former and 11 days in the latter. The cerebral hemispheres showed this by 25-30 days in pigeon and swift and 14 days in sparrow. The hind brain regions showed maximum activity followed by optic lobes, cortex, basal ganglia and cerebellum. The development of the enzyme activity coincided with myelination, in the different areas, as well as with the development of other mitochondrial enzymes. The study indicates that the maturation of the monoaminergic neurotransmitter systems occurs by 30 days in pigeon and swift, while it takes only about half that time i.e., 14 days, in sparrow.

Aging↗
PubMed1978

Characteristics of lead ion-stimulated phosphorylation of Electrophorus electricus electroplax (Na+ + K+)-adenosine triphosphatase and inhibition of ATP-ADP exchange.

Pb2+-stimulated phosphorylation of Electrophorus electricus electroplax (Na+ + K+)-adenosine triphosphatase is prevented by stoichiometric quantities of 2,3-dimercaptopropanol. The chelator in the same low concentrations does not block Na+-dependent phosphorylation. Both Pb2+-and Na+-dependent phosphorylation reactions show the same dependence on MgCl2. Phosphorylation in the presence of both Na+ and Pb2+ is cumulative suggesting that Pb2+ and Na+ bind at separate, independent sites. The enthalpy change due to binding of Pb2+ is about -1.76 kcal/mol. 32P-phosphopeptides obtained from pronase or pepsin digests of Pb2+-and Na+-dependent phosphoproteins are electrophoretically identical. Pb2+ does not stimulate but does inhibit ATP-ADP exchange activity under the conditions in which this activity is stimulated by Na+. Since the phosphorylation sites are identical, it is concluded that the differences in reactivity of the Na+- and Pb2+-phosphoenzymes are due to different conformational changes produced by binding of Na+ and Pb2+. The Pb2+-sensitive conformation is critical for Na+ specificity of phosphorylation, reversibility of phosphorylation, and for phosphatase activity but not for acceptor site phosphorylation by ATP. These findings have implications for enzyme reaction models.

Adenosine Diphosphate↗
PubMedDate not supplied

Dose-response study of the analgesic effect of lanepitant in patients with painful diabetic neuropathy.

Lanepitant is effective in the formalin analgesic model suggesting efficacy in painful neuropathy. This study was designed to evaluate the dose-response effect of lanepitant in patients with daily moderate to severe, bilateral, distal neuropathic pain. After a 1-to 3-week lead-in period, patients were randomly allocated to double-blind, parallel treatment with lanepitant 50 mg daily (n = 27), 100 mg daily (n = 27), 200 mg twice daily (n = 13), or placebo (n = 26) over 8 weeks. Patients reported average daytime pain and average nighttime pain intensity. Plasma concentrations and amount of adjunctive analgesic medication were obtained at all visits after baseline. Patient global evaluation and clinician global impression were obtained at weeks 3 and 8. Safety was assessed by adverse events, vital signs, laboratory analytes, and electrocardiogram. No dosage of lanepitant differed significantly from placebo. Efficacy did not increase with lanepitant dosage, and higher plasma concentrations were no more effective than lower plasma concentrations. The adverse event diarrhea was more frequent for lanepitant-treated patients. Although well tolerated, lanepitant was ineffective in relieving pain of diabetic neuropathy.

Aged↗
PubMedDate not supplied

Stimulatory tests of growth hormone secretion in prepubertal major depression: depressed versus normal children.

OBJECTIVE: Blunted stimulation of growth hormone (GH) secretion after pharmacological stimuli has been linked to depressive and anxiety disorders throughout the life span. This study sought to better characterize this dysregulation in prepubertal depression. METHOD: GH regulation was compared in 38 medically healthy prepubertal children with current major depressive disorder and 19 control children who were medically and psychiatrically healthy. The study evaluated GH stimulatory responses to three pharmacological challenge agents: (1) insulin-induced hypoglycemia, using 0.1 IU/kg intravenous regular insulin; (2) 1.3 micrograms/kg intravenous clonidine; and (3) 1.0 microgram/kg intravenous human growth hormone-releasing hormone (GHRH). RESULTS: The results provide replication and extension of earlier findings. GH responses to insulin-induced hypoglycemia and to GHRH stimulation were blunted in depressed children compared to the normal controls. Clonidine stimulation results yielded a similar picture but did not reach statistical significance. CONCLUSIONS: Overall these results further strengthen the evidence showing GH dysregulation in childhood depression. However, the blunted GH response seen with GHRH (which reflects pituitary hyporesponsivity) was in contrast to our original hypothesis and has implications regarding the site (or sites) of dysregulation.

Adolescent↗