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Biomedical subjects

R Prasad

Publications and source records attributed to R Prasad.

At least 379 records · Page 21Linked to original sources
PubMed1977

Isolation and comparison of ribothymidine-lacking tRNAs of fetal, newborn and adult bovine tissues.

Although ribothymidine (rT) is the most common methylated nucleoside in tRNA, a wide variety of bovine tissues have now been found to contain a class of tRNAs which totally lack rT and have an unmodified uridine in its place. The tissues studied include bovine brain, kidney, liver, thymus and testicles from adult, newborn and fetal stages. The class of tRNA was detected by its ability to be methylated with Escherichia coli rT-forming uracil methylase with radioactive S-adenosyl-L-methionine as the methyl donor. In each case rT was shown to account for at least 95% of the methylated products produced. In vitro methylated tRNA populations were compared by fractionation of double-labeled tRNAs on RPC-5 columns. Three major methyl-accepting tRNA peaks were found for all mammalian tissues studied. The level of methyl acceptance in these peaks was found to vary considerably between tRNAs of different tissues. A major difference in the methyl-accepting tRNA populations of bovine liver and calf thymus was observed. Little similarity was found in the rT-lacking class of tRNAs of bovine liver and wheat germ. Three members of the rT-lacking class of bovine liver tRNA were isolated and found to be two species of valine tRNA and one species of threonine tRNA. All three tRNA's completely lacked rT and could be quantitatively methylated with E. coli uracil methylase.

Aging↗
PubMed1977

Effect of irradiation on electrophoretic properties of enzymes in haemopoietic cells of opossum.

5-month-old male opossums were exposed to 5000 rads whole body 60Co radiation and sacrificed at 16, 40 and 90 h following irradiation. Stract gel electrophoretic studies of dehydrogenases of lactate, malate, 6-phospho-gluconate and glucose-6-phosphate and alpha-esterases and acid phosphatase were conducted on the homogenates of spleen and bone marrow cells. Expressions of LDH and G6PD were affected by irradiation in bone marrow and spleen cells.

Animals↗
PubMed1977

Insoluble human plasma protein immunoadsorbents. Large-scale production and storage.

Methods for producing and preserving large volumes of insoluble immunoadsorbents (for removing unwated antibodies to serum proteins) from surplus blood bank plasma by glutaraldehyde were evaluated by quantitative and qualitative means using radioactive 125I and immunoelectrophoresis, respectively. Some of the factors affecting the desired physical characteristics and antibody-absorbing properties of the imjunoadsorbent studied were: plasma acidification, varying concentrations of glutaraldehyde, addition of small amounts of formalin, storage under varying conditions of temperature, and exposure to preservatives in the wet and lyophilized state for periods up to 2.5 years. The best preservation of antibody-adsorbing properties (under storage conditions) was obtained in the washed state at 4 degrees C, but good preservation was also obtained at room temperature in the presence 10% formalin and in the unwashed state at room temperature in the presence of unreacted glutaraldehyde. Lyophilization destroyed about 70% of an adsorbent's activity.

Animals↗
PubMed1977

The biosynthesis of dimethyltryptamine in vivo.

The in vivo formation of dimethyltryptamine was studied in rabbits, rats and monkeys. When C14-labelled N-methyltryptamine was administered by intravenous injection to rabbits, C14-dimethyltryptamine was found in lung, the principle site of the methyltransferase that biosynthesizes this psychotogen. Unequivocal evidence for C14-dimethyltryptamine formation in rat tissues was not obtained. When rabbits were given non-radioactive N-methyltryptamine intravenously, dimethyltryptamine appeared in carotid arterail blood, peaking within the first minute after injection of the precursor. USing this assay procedure we could not demonstrate dimethyltryptamine synthesis in the rhesus monkey.

Animals↗
PubMed1977

Effect of irradiation on testicular cells of opossum.

Five months old male opossums were exposed to 5000 rd wholebody 60Co gamma-radiation. Testes tissues from animals sacrificed at 16, 40 and 90 hours post-irradiation and from nonirradiated animales were used for enzymatic and histological studies. Electrophoretic pattern of lactate dehydrogenase and glucose-6-phosphate dehydrogenase was slightly disturbed in early hours in irradiated animals, but it did not persist beyond 40 hours postirradiation. Histological study indicates 31% survival of type A spermatogonia suggesting high radioresistance of testes tissue in comparison to other animals.

Animals↗
PubMed1977

Induction of hepatic aryl hydrocarbon hydroxylase in C57BL mice by ionizing radiation.

Inbred strains of C57BL mice were exposed to either 100, 500, or 1000 rads of whole-body irradiation. Another group of mice were given injections of 3-methylcholanthrene only, and a control group had no treatment. Forty-eight hr after treatment, the animals were killed and hepatic aryl hydrocarbon hydroxylase (AHH) activity was measured by spectrophotofluorometer. A comparison of hepatic AHH activity in treated and nontreated groups of mice showed that each treated group had a significantly increased AHH induction compared with the control group. Although radiation appeared to have a dose-related effect on AHH induction, the increase with dose level was not statistically significant.

Animals↗
PubMed1976

Different mechanisms of energy coupling for transport of various amino acids in cells of Mycobacterium phlei.

Whole cells of Mycobacterium phlei were shown to actively accumulate proline, leucine, lysine, tryptophan, histidine, glutamine, and glutamic acid to different steady state levels. The transport of proline, in contrast to that of other amino acids, was found to be insensitive to various respiratory inhibitors, e.g. cyanide, arsenate, azide, and sulfhydryl reagents. However, oxygen was an obligatory requirement for the uptake of proline, as well as for the other amino acids. The results indicate that the energy requirements for proline uptake are different from those of other amino acids. In contrast to the system from Escherichia coli, the mode of energy transduction for the uptake of proline, glutamine, and glutamic acid is different even though these amino acids are shock resistant in the M. phlei system.

Adenosine Triphosphate↗
PubMed1976

Lactate and malate dehydrogenase and alpha-esterases in oligospermia.

Lactate dehydrogenase (LDH), malate dehydrogenase, and alpha-esterase were studied electrophoretically in a total of 99 semen samples obtained from normal, vasectomized, oligospermic, and infertile males. The enzymatic patterns were compared with total sperm count and percentage sperm motility. Lactate dehydrogenase X was absent in semen samples from oligospermic as well as vasectomized males. An extra LDH band (between the second and third LDH bands) was detectable in samples which had a low sperm count but higher motility (80 to 90%). This extra band was absent in samples with higher sperm count regardless of the level of percentage motility, suggesting that the extra band possibly may be related to motility factors of low sperm count but not normal sperm count. The fastest moving alpha-esterase bands were absent in samples from oligospermic or vasectomized males. These bands were also absent in samples from infertile patients having a very low sperm count. It is not clear whether the fast-moving esterase bands are related to sperm count or possible differences in hormonal levels of individuals with low or zero sperm count samples. The patterns of malate dehydrogenase did not differ in individuals with zero, low, or normal sperm count.

Electrophoresis, Starch Gel↗
PubMed1976

Altered enzyme expression in "differentiated" murine neuroblastoma cells.

Out of 17 enzymes studied, only 9 were detectable by starch gel electrophoresis in mouse neuroblastoma cells in culture. Prostaglandin E1 (PGE1) and 4(-3-butoxy-4-methoxybenzyl)-2-imidazolidinone (R020-1724), a specific inhibitor of cAMP phosphodiesterase, were used to induce "differentiation". Lactate and 6-phosphogluconate dehydrogenases and adenylate kinase were expressed as single bands in untreated neuroblastoma and induced "differentiated" cells, but the electrophoretic mobility of these enzymes in PGE1-treated cells was slower than that in malignant and R020-1724-treated cells. Three bands of glucose 6-phosphate dehydrogenase were detectable in PGE1-treated cells, whereas the R020-1724-treated cells had two bands and the untreated neuroblastoma cells had only one band. Aldolase was also expressed as a single band; however, the activity of this enzyme was much higher in PGE1-treated cells, whereas the activity was bately detectable for R020-1724-treated and untreated neuroblastoma cells. Some of the enzymes which are present in vivo are absent in vitro. Alkaline phosphatase is present in brain but is absent in neuroblastoma cells in vivo and in vitro. Two bands each of triose phsophate isomerase, fumarase and aldolase are present in brain, but only one band of these enzymes is present in neuroblastoma cells. Although PGE1 and R020-1724 induce many differentiated functions in neuroblastoma cells in a similar manner, PGE1 appears to change characteristically the expression of several enzymes.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗