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Biomedical subjects

A K Roy

Publications and source records attributed to A K Roy.

At least 163 records · Page 9Linked to original sources
PubMed1980

Messenger RNA for alpha 2u-globulin of rat liver. Purification, partial characterization of the mRNA, and synthesis of a Hae III restriction fragment as its cDNA probe.

The mRNA for the androgen-dependent hepatic protein, alpha 2u-globulin is normally present in the liver of mature male rats to the extent of about 1% of the total mRNA population. alpha 2u mRNA which was found to migrate as a 14 S band was purified about 18-fold through preparative urea-agarose gel electrophoresis. 32P-Labeled cDNA synthesized with this partially purified alpha 2u mRNA was used as substrate for two restriction endonucleases Hha I and Hae III. Digestion of the cDNA with Hha I failed to reduce its electrophoretic heterogeneity. However, Hae III digestion of the cDNA preparation greatly reduced the molecular complexity and produced several distinct cDNA bands. One of these Hae III fragments (Band A) containing 410 nucleotide residues was extracted from polyacrylamide gel and found to be complementary to alpha 2u mRNA. The identity of this cDNA fragment was established by its ability to inhibit selectively the translation of alpha 2u mRNA in the rabbit reticulocyte cell-free system and by its hybridization kinetics with poly(A)+ hepatic RNA from animals with different rates of alpha 2u synthesis. The relative R0t 1/2 values showed a direct correlation between mRNA sequences complementary to the cDNA fragment (A) and to both translatable alpha 2u mRNA and hepatic level of alpha 2u-globulin in adult male, female, and maturing male rats. Thus, the cDNA fragment containing 410 nucleotide residues generated by the restriction cleavage with Hae III can be used as a convenient probe for identification and quantitation of alpha 2u mRNA under different physiological and experimental conditions.

Alpha-Globulins↗
PubMed1980

Multiple hormone requirement for the synthesis of alpha 2u-globulin by monolayers of rat hepatocytes in long term primary culture.

Primary cultures of adult rat hepatocytes were prepared by releasing liver cells through fractional trypsinization and by a novel nonenzymatic procedure involving the imprinting of liver explants on the surface of the culture flask (explant imprinting). The comparative properties of these two primary cultures and their abilities to synthesize alpha 2u-globulin under multihormonal stimulation were investigated. The hepatocytes isolated from male rats by fractional trypsinization were found to divide rapidly and form a confluent monolayer within 5-7 days of culture. However, these cells failed to synthesize alpha 2u-globulin even after treatment with 5 alpha-dihydrotestosterone, GH, T3, and dexamethasone, hormones with known stimulatory effects on the synthesis of alpha 2u-globulin in vivo. On the contrary, hepatocytes prepared from male rats by the nonenzymatic procedure of explant imprinting were found to synthesize alpha 2u-globulin for more than 2 weeks and responded to GH, T3, and dexamethasone with enhanced production of this protein. Fortification of the culture medium with all of the above three hormones caused an approximately 9-fold enhancement of alpha 2u production within 4 days of culture compared to production in control culture without these hormones. The above results substantiate earlier findings concerning the multiple hormonal requirement for hepatic synthesis of alpha 2u-globulin in vivo and show that isolation and culture of hepatocytes by nonenzymatic explant imprinting may serve as a useful procedure for studying endocrine regulation of gene activity in vitro.

Alpha-Globulins↗
PubMed1980

A rapid, centrifugation-free radioimmunoassay specific for human chorionic gonadotropin using glass beads as solid phase.

A simple, specific, rapid, centrifugation-free solid phase RIA for hCG has been developed. Purified gamma-globulin isolated from antisera produced against hCG-beta in rabbits is covalently linked to glutaraldehyde-activated aminopropyl glass beads. The entire assay can be completed within 3 h at room temperature. The sensitivity (1 ng/ml), precision (intra- and interassay variabilities, less than 10% and less than 15%, respectively), and specificity (0.4% cross-reactivity with LH) are comparable to other methods. The hCG levels determined by the present method show good correlation with those obtained by another RIA and by radioreceptorassay. The present method also provides the basis for the development of similar rapid and sensitive assays of other hormones.

Chorionic Gonadotropin↗
PubMed1979

DEAE-silica gel and DEAE-controlled porous glass as ion exchangers for isolation of glycolipids.

DEAE-silica gel and DEAE-controlled porous glass have been used for the quantitative isolation of gangliosides and neutral glycosphingolipids from animal tissues and cells. A direct comparative study between DEAE-silica gel, DEAE-controlled porous glass and DEAE-Sephadex was made; the results indicated that DEAE-silica gel is preferable to the other two ion exchangers. DEAE-silica gel has also been found to be suitable for the fractionation of ganglioside mixtures.

Adult↗
PubMed1979

Superinduction of alpha 2u globulin by actinomycin D: evidence for drug-mediated increase in alpha 2u mRNA.

Actinomycin D, an inhibitor of DNA-dependent RNA synthesis, increased the hepatic concentration of alpha 2u globulin, an androgen-inducible protein in the rat. Spayed female rats with a marginally induced state of alpha 2u synthesis showed an approximately 5-fold increase in hepatic alpha 2u globulin within 3-6 hr after treatment with actinomycin D. Initial treatment of these animals with 5 alpha-dihydrotestosterone, followed by actinomycin D, resulted within 2-3 hr in a more than 2-fold increase in hepatic alpha 2u globulin compared to animals treated with the androgen alone. In spite of inhibition of hepatic synthesis of poly(A)-containing RNA to less than 25% of control, superinduction with actinomycin D resulted in a parallel increase in the translatable mRNA for alpha 2u globulin. These results showing increase in both alpha 2u globulin and its translatable mRNA after superinduction with actinomycin D support the concept of post-transcriptional repression of alpha2u synthesis.

Alpha-Globulins↗
PubMed1979

Hereditary factors in stammering.

A pedigree from Hazaribagh District of Bihar (india) with 12 stammerers spread over five generations was analysed for the mode of inheritance of stuttering. A predisposition seems to be a prerequisite for its occurrence. The relative roles of heredity an environment in the expression of stammering were evaluated. Transmission appears to be by a dominant autosomal. Variable expressivity, incomplete penetrance as well as partial sex-limitation as other causes have also been considered.

Adult↗
PubMed1977

Studies on the mode of oestrogenic inhibition of hepatic synthesis of alpha2u-globulin and its corresponding messenger ribonucleic acid in rat liver.

1. The possible mechanism of the oestrogenic inhibition of the androgen-dependent synthesis of alpha2u-globulin in rat liver was explored by a correlative study of the amounts of alpha2u-globulin, its corresponding mRNA and circulating testosterone in oestrogen-treated male rats. 2. Daily treatments of mature male rats with oestradiol-17beta (10 microgram/100g body wt.) decreased and ultimately stopped the hepatic synthesis of alpha2u-globulin as determined by both hepatic and urinary concentrations of the protein. The oestrogen-mediated decrease in the hepatic synthesis of alpha2u-globulin was correlated with a decrease in the mRNA for this protein. 3. Withdrawal of oestrogen resulted in the recovery of alpha2u-globulin synthesis and an increase in mRNA for alpha2u-globulin. 4. At higher doses of oestradiol-17beta (50 microgram/100g body wt.), synthesis of alpha2u-globulin was totally suppressed. In addition, this treatment resulted in an extended period of androgen-insensitivity during which treatment with androgens induced synthesis of neither alpha2u-globulin nor its corresponding mtrna. 5. it is concluded that the oestrogenic inhibition of alpha2u-globulin synthesis is mediated by an oestrogen-dependent decrease in the hepatic content of translatable mRNA for alpha2u-globulin.

Alpha-Globulins↗
PubMed1977

Early events in the steroidal regulation of alpha2mu globulin in rat liver. Evidence for both androgenic and estrogenic induction.

1. A double-antibody radioimmunoassay for alpha2mu globulin has been developed. With the help of this highly sensitive radoimmunoassay the early effects of both androgen and estrogen treatments on the hepatic synthesis of alpha2mu globulin in the rat have been investigated. 2. Results show that the earlier observation of the long lag period in the androgenic induction of alpha2mu globulin is more apparent than real. 3. Single injections of either 5alpha-dihydrotestosterone(5alpha-dihydro-17beta-hydroxy-4-androsten-3-one) or its physiological antagonist estradiol-17beta (1,3,5(10)-estratriene-3,17beta-idol) to castrated female rats resulted in the induction of alphamu globulin reaching maximum hepatic level of the protein between 6--9 h after the hormone administration. Administration of cycloheximide 15 prior to hormone treatment blocked both androgenic andestrogenic induction of alpha2mu globulin. 4. Daily pretreatments with 5alphamu-dihydrotestosterone increased the sensitivity of subsequent androgenic response to alpha2muglobulin synthesis. On the other hand, daily pretreatments with estradiol 17beta decreased and ultimately abolished the estrogenic induction of alpha2mu globulin. 5. The possible mechanism of both androgenic and estrogenic induction of alpha2mu globulin in rat liver mediated through a sex-hormone-binding protein with dual affinity for both dihydrotestosterone and estradiol has been suggested.

Animals↗