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Biomedical subjects

T R Rao

Publications and source records attributed to T R Rao.

At least 19 recordsLinked to original sources
PubMed1997

Rapid and selective analysis of secnidazole in human plasma using high-performance liquid chromatography with ultraviolet detection.

A rapid, reproducible high-performance liquid chromatographic method for the determination of secnidazole, 5-nitroimidazole class of antiprotozoals from blood is described. Metronidazole was used as an internal standard. A simple extraction step with dichloromethane was done before chromatography on a C18 column with the wavelength fixed at 276 nm on the UV detector. Blood levels up to 500 ng/ml have been measured with good precision in the healthy volunteers after 1 g of secnidazole was administered. The present described method can readily be utilized for routine pharmacokinetic studies.

Antiprotozoal Agents↗
PubMed1996

Significance of lymphocytic sister chromatid exchange frequencies in ovarian cancer patients.

Very few studies report the analysis of sister chromatid exchanges in ovarian cancer patients. We tested the null hypothesis that SCE frequency increases with the advancing stages of ovarian cancer and follows a Poisson distribution. As controls we examined age- and sex-matched healthy volunteers who had no such past history. An increased average SCE frequency was observed in ovarian cancer patients (6.34 +/- 0.09) vis-à-vis controls (4.47 +/- 0.12). Further, the data also suggested a stage-wise increase in the SCE frequency.

Adult↗
PubMed1996

An evaluation of antidepressants in rheumatic pain conditions.

In a randomized, double-blind, parallel study, fluoxetine and amitriptyline were compared with placebo in the treatment of chronic rheumatic pain. A total of 59 patients were evaluated during 4 wk of treatment and received 20 mg fluoxetine, 25 mg amitriptyline, or placebo daily. Pain intensity, pain relief, vital variables, and global evaluation were used to assess efficacy. To evaluate safety variables, the incidence of side effects was noted. Both amitriptyline and fluoxetine significantly reduced pain intensity compared with placebo. Similarly, pain relief was greater with both amitriptyline and fluoxetine than with placebo. At the end of the fourth week, fluoxetine was superior in efficacy to amitriptyline. The incidence of adverse effects was significantly greater with amitriptyline; dryness of the mouth was the most predominant side effect. We conclude that fluoxetine is an effective analgesic with fewer side effects.

Adult↗
PubMed1992

Spatio-temporal expression of estrogen sulfotransferase within the hepatic lobule of male rats: implication of in situ estrogen inactivation in androgen action.

Estrogen sulfotransferase (EST) catalyzes transfer of the sulfate group from phosphoadenosine phosphosulfate to estrogenic steroids. Since estrogen sulfates do not bind to the estrogen receptor with high affinity, EST can control the intracellular level of the receptor-active estrogens. Androgen action in the rat liver, as indicated by the androgenic induction of alpha 2u-globulin, is inhibited by low levels of estrogens. Thus, in situ estrogen inactivation by EST is expected to increase hepatic androgen sensitivity. During the lifespan of the animal, rat liver undergoes three distinct phases of androgen sensitivity, i.e. prepubertal androgen insensitivity, androgen sensitivity after approximately 40 days of age, and androgen insensitivity during senescence (greater than 750 days). EST in the liver is expressed only after puberty, when the liver becomes androgen sensitive. Furthermore, localization of EST and its corresponding mRNA within the lobular unit of the liver demonstrates that only androgen-responsive hepatocytes located around the central vein contain immunoreactive EST and its corresponding mRNA. These temporal and spatial correlations of EST expression and hepatic androgen sensitivity support the concept that steroid-inactivating enzymes play important roles in sex hormone action.

Aging↗
PubMed1992

Estrogen sulfotransferase of the rat liver: complementary DNA cloning and age- and sex-specific regulation of messenger RNA.

Mammalian estrogen sulfotransferase (EST; EC 2.8.2.4) sulfurylates the hydroxyl group of estrogenic steroids by transferring the sulfate from a cosubstrate adenosine 3'-phosphate-5'-phosphosulfate. Sulfurylated steroids do not bind to the estrogen receptor with high affinity and, therefore, are hormonally inactive. We have purified rat liver EST and developed monoclonal antibody to this enzyme. By immunoscreening a lambda gt-11 expression library constructed from male rat liver cDNAs, the cDNA clone corresponding to EST was identified and isolated. A recombinant expression plasmid (pCMV5) containing this cDNA insert when transfected into COS-7 cells generated both immunologically and enzymatically active EST. With the help of this cDNA probe, we have explored the regulation of the EST mRNA in the liver and the possible role of this enzyme in sex hormone action. During the lifespan of male rats, only the young adult animals show hepatic androgen responsiveness. Also, estrogenic hormones strongly antagonize androgen action in the rat liver. Northern blot analysis of liver RNA derived from male rats of different ages shows that the androgen sensitivity of young adult animals is associated with a high expression of EST mRNA. During the same period, mRNA corresponding to dehydroepiandrosterone sulfotransferase is markedly (approximately 10-fold) down-regulated. Such a correlation is in concordance with the role of these enzymes in the maintenance of hepatic androgen sensitivity during young adult life by inactivating the estrogenic and sparing the androgenic steroids. Furthermore, the increase in the hepatic androgen sensitivity of androgen-treated female rats is also associated with the induction of EST.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Immediately preovulatory levels of messenger ribonucleic acid for inhibin alpha-subunit are diminished in granulosa cells from successful in-vitro fertilization-embryo transfer.

Inhibin, a gonadal glycoprotein which suppresses pituitary gonadotrophin secretion, preferentially follicle stimulating hormone, has been extensively characterized. It consists of two covalently bound subunits, the alpha- and beta-subunits, encoded by separate genes. In this study, the expression of messenger ribonucleic acid (mRNA) for the inhibin alpha-subunit was studied by Northern blot analysis in granulosa cells of women undergoing in-vitro fertilization/embryo transfer (IVF/ET). Three patient groups were studied: women who failed to become pregnant (n = 11), women who became pregnant but experienced early spontaneous abortion (n = 3) and women who conceived normal ongoing pregnancies (n = 4). Granulosa cells were obtained at the time of follicle aspiration. Levels of alpha-subunit mRNA were 40% lower in patients establishing normal pregnancies than in those who failed to become pregnant or who spontaneously aborted. Thus, a relative diminution of immediately preovulatory levels of mRNA for inhibin alpha-subunit is a marker of success in clinical IVF/ET cycles. This marker of IVF/ET success can be related to previously established markers of success (increased follicular fluid oestradiol and decreased follicular fluid cyclic adenosine monophosphate) by known physiological mechanisms.

Adult↗
PubMed1991

Androgen receptor messenger ribonucleic acid (mRNA) in the rat liver: changes in mRNA levels during maturation, aging, and calorie restriction.

By means of RNAase protection assay with an antisense cRNA probe, we have shown that the liver of the young adult male rat contains androgen receptor (AR) mRNA to a level of 4% compared to the prostate. Steady state levels of AR mRNA in the liver show both sex and age specificity. Compared to that of the male, the female liver contains a markedly reduced amount of AR mRNA. AR mRNA is almost undetectable in livers of prepubertal male (less than 35 days old) and senescent male (greater than 750 days old) rats. Both prepubertal and senescent animals are relatively insensitive to the androgenic induction of alpha 2u-globulin, a hepatic secretory protein. The age-dependent decline in hepatic androgen sensitivity and AR mRNA level can be delayed considerably by a 40% reduction in the dietary calorie intake. Analysis of poly(A)-containing RNA from two liver cell populations, hepatocytes and nonhepatocytes, revealed that only the hepatocytes that express alpha 2u-globulin gene contain AR mRNA. From these results and our earlier observation of in vitro induction of alpha 2u-globulin in isolated rat liver, we conclude 1) that androgen can act directly on hepatocytes to promote alpha 2u-globulin synthesis; 2) that changes in the hepatic androgen sensitivity during maturation and aging are reflections of the age-dependent expression of the receptor gene; and 3) that retardation of the age-dependent loss of androgen sensitivity by calorie restriction is due to a concomitant delay in the decline of the hepatic AR mRNA level.

Aging↗
PubMed1991

Characterization of Int-5, a locus associated with early events in mammary carcinogenesis.

Three chemically-induced precancerous mammary hyperplasias, independently isolated in BALB/c mice, all contained mouse mammary tumor virus (MMTV) proviral DNA integrated into a common region in chromosomal DNA, designated Int-5 (Formerly Int-H, Gray et al., 1986). This site was cloned from a hyperplastic outgrowth (D2) into lambda phage. A 1.7 Kb Hind III DNA fragment, which flanks the 5' end of the MMTV insert, was generated from the cloned Int-5 region. This fragment was used as probe (IH-2) to localize Int-5 to mouse chromosome 9. The IH-2 sequence was highly conserved in DNA of several mammalian species including man, in three other widely divergent vertebrate phyla, and in C. elegans. The Int-5 region, containing 5.6 Kb 5' and 12.8 Kb 3' to the MMTV integration site in D2, was cloned in EMBL-3 from a BALB/c genomic DNA library. cDNA complementary to poly A+ lactating mammary gland RNA, annealed with Sst-1 fragments spanning most of the BALB/c Int-5 clone. The highest level of Int-5 specific poly A+ mRNA was detected in D2 tumor. Lactating mammary gland and D2 hyperplastic alveolar nodule contained 5-fold less Int-5 RNA while liver contained 8-fold less Int-5 RNA. Int-5 cDNA (IH-3) annealed with two RNA species of approximately 3.3 and 4.0 Kb. These data are consistent with the hypothesis that Int-5 contains an oncogene, different from any other previously described, involved in early events in some models of chemical carcinogenesis.

Animals↗
PubMed1989

Use of a shuttle vector for the transformation of the white rot basidiomycete, Phanerochaete chrysosporium.

A novel shuttle vector based spheroplast transformation system for the lignin degrading filamentous fungus P. chrysosporium is described. The transformation vector, designated pRR12, consists of the yeast integration plasmid YIp5, a putative autonomous replication sequence (ars) of P. chrysosporium, and a 2.2 kb PvuII fragment carrying kanr determinant from plasmid pNG35, which confers resistance against both kanamycin and the related antibiotic G418. Two different strains of P. chrysosporium (ME446 and BKM-F) were transformed to G418 resistance using vector pRR12. Approximately 20 transformants per micrograms of vector DNA were obtained. The transforming vector pRR12 could be recovered from the total DNA of transformants by E. coli transformation, albeit at a low frequency.

Basidiomycota↗
PubMed1988

The stability of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells varies with growth rate.

The decay rates of eucaryotic elongation factor Tu (eEF-Tu) mRNA and eucaryotic initiation factor 4A (eIF-4A) mRNA in Friend erythroleukemia (FEL) cells were determined under several different growth conditions. In FEL cells which were no longer actively dividing (stationary phase), eEF-Tu mRNA was found to be rather stable, with a t1/2 of about 24 h. In rapidly growing FEL cells eEF-Tu mRNA was considerably less stable, with a t1/2 of about 9 h. In both cases a single rate of mRNA decay was observed. However, when stationary-phase cells resumed growth after treatment with fresh medium, we observed that eEF-Tu mRNA decay followed a biphasic process. The faster of the two decay rates involved approximately 50% of the eEF-Tu mRNA and had a t1/2 of about 1 h. The decay rates for eIF-4A (t1/2 = 2 h) and total poly(A)+ RNA (t1/2 = 3 h) were unaffected by changes in growth conditions. The t1/2 for polysomal eEF-Tu mRNA was found to be about 8 h when stationary FEL cells were treated with fresh medium. Previous work in this laboratory has shown (T. R. Rao and L. I. Slobin, Mol. Cell. Biol. 7:687-697, 1987) that when FEL cells are allowed to grow to stationary phase, approximately 60% of the mRNA for eEF-Tu is found in a nontranslating postpolysomal messenger ribonucleoprotein (mRNP) particle. eEF-Tu mRNP was rapidly cleared from stationary cells after treatment with fresh medium. The data presented in this report indicate that the stability of eEF-Tu mRNP is rapidly altered and the particle is targeted for degradation when stationary FEL cells resume growth.

Cell Division↗
PubMed1987

Regulation of the utilization of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells.

When Friend erythroleukemia cells were allowed to grow to stationary phase (2 X 10(6) to 3 X 10(6) cells per ml), approximately 60% of the mRNA for eucaryotic elongation factor Tu (eEF-Tu) sedimented at less than or equal to 80S, and most of the remaining factor mRNA was associated with small polysomes. Under the same growth conditions, greater than 90% of the mRNA for eucaryotic initiation factor 4A remained associated with polysomes. The association of eEF-Tu mRNA with polysomes changed dramatically when stationary-phase cells were treated with fresh medium. After 1 h in fresh medium, approximately 90% of eEF-Tu mRNA in Friend cells was found in heavy polysomes. Associated with the shift of eEF-Tu mRNA into heavy polysomes, we found at least a 2.6-fold increase in the synthesis of eEF-Tu in vivo as well as a remarkable 40% decrease in the total amount of eEF-Tu mRNA per cell. Our data raise the possibility that eEF-Tu mRNA that has accumulated in ribonucleoprotein particles in stationary-phase cells is degraded rather than reutilized for eEF-Tu synthesis.

Animals↗
PubMed1984

DNA sequences from a ligninolytic filamentous fungus Phanerochaete chrysosporium capable of autonomous replication in yeast.

Five different DNA sequences of Phanerochaete chrysosporium capable of supporting autonomous replication of yeast integration plasmid (YIp5) in Saccharomyces cerevisiae were isolated. These hybrid plasmids with the autonomous replication sequences from P. chrysosporium are maintained extra-chromosomally, are mitotically unstable and transform Ura3 deletion mutant of S. cerevisiae to Ura+ phenotype with high frequency. The autonomous replication sequence in pRR2, one of the recombinant plasmids, was further characterized and was shown to be homologous to P. chrysosporium genomic DNA. Restriction analyses showed that this plasmid has unique PvuII and SalI restriction sites for cloning.

Base Sequence↗
PubMed1982

Colorectal linitis plastica.

Primary linitis plastica of the colon is an uncommon tumor, with only 22 cases having been previously reported. Experience with two men and one woman between 17 and 55 years of age, portraying a spectrum of clinical presentations ranging from rectal bleeding to large-bowel obstruction, is reviewed. Clinical and radiologic characteristics and histologic features helpful in making the diagnosis are detailed. Though the prognosis is grim, resective surgery, including oophorectomy in women, should be undertaken. Adjuvant therapy has been disappointing.

Adenocarcinoma, Scirrhous↗