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Biomedical subjects

S Sarkar

Publications and source records attributed to S Sarkar.

At least 325 records · Page 18Linked to original sources
PubMed1987

Diagnostic utility of hepatobiliary scintigraphy with 99mTc-DISIDA in neonatal cholestasis.

We retrospectively evaluated the utility of hepatobiliary scintigraphy and various clinical factors in differentiating intrahepatic cholestasis from biliary atresia in 28 consecutive infants with neonatal cholestasis. One millicurie of technetium-labeled diisopropyliminodiacetic acid (DISIDA) was administered intravenously, and images were obtained for up to 24 hours or until gastrointestinal excretion was noted. Nine separate studies in seven infants with biliary atresia were correctly interpreted as showing no gastrointestinal excretion of radionuclide. Of the 21 patients with intrahepatic cholestasis, only nine had gastrointestinal excretion on the first study; in eight without excretion, a second study was done, and five of these showed gut excretion. All infants with either neonatal hepatitis (six) or inspissated bile syndrome (three) had demonstrable gastrointestinal excretion either on the first or second DISIDA study. However, five of six infants with paucity of intrahepatic bile ducts, two of six infants with cholestasis secondary to total parenteral nutrition, and one infant with cholangiolitis did not show evidence of gastrointestinal excretion. The mean birth weight, mean gestational age, and mean weight at study were significantly greater (P less than 0.005) for infants with biliary atresia without excretion than for infants with intrahepatic cholestasis without excretion. The mean direct bilirubin concentration was 6.0 mg/dL for both infants with biliary atresia and infants with intrahepatic cholestasis without excretion; however, infants with excretion had a significantly lower (P less than 0.02) mean direct bilirubin value of 3.4 mg/dL. Excretion was noted in four infants with total bilirubin values greater than 10.0 mg/dL. The absence of gut excretion on the first DISIDA study was 100% sensitive but only 43% specific for biliary atresia. In infants without gut excretion of DISIDA, birth weight greater than 2200 g was 100% sensitive and 92% specific for biliary atresia. We conclude that DISIDA scanning, together with clinical data, is useful in differentiating extrahepatic from intrahepatic cholestasis. The absence of gut excretion on the first DISIDA study does not necessarily indicate extrahepatic obstruction; the study should be repeated if the diagnosis is not clear.

Bile Ducts, Intrahepatic↗
PubMed1987

Mutagenicity of extracts of brown and black masheri, pyrolysed products of tobacco using short-term tests.

Black and brown varieties of masheri, which are pyrolysed tobacco products were analysed for their mutagenic potentials using a battery of test systems. Both materials were found to be mutagenic in Salmonella typhimurium strain TA98 with metabolic activation and also in V79 Chinese Hamster cells producing 8-azaguanine resistant mutations. Both varieties were found to induce statistically significant increases in micronuclei formation as compared to those produced in the solvent controls. Both varieties induced structural chromosomal aberrations in bone marrow cells of mice. Our data suggest that masheri is a potent mutagen in a variety of test systems and is likely to have a mutagenic potential vis à vis humans.

Animals↗
PubMed1986

Demonstration of myc and ras oncogene expression by hybridization in situ in hydatidiform mole and in the BeWo choriocarcinoma cell line.

With the use of hybridization in situ, c-myc and c-ras oncogene expression has been identified in the cytotrophoblast of hydatidiform mole and in the malignant trophoblast cell line BeWo. Expression was also found in early villous placenta. No expression of these two oncogenes was found in the cytotrophoblast of an 11-week conceptus, nor was it found in term placenta. The significance of these findings is discussed.

Cell Line↗
PubMed1986

Small nuclear ribonucleoprotein antigens are absent from 10S translation inhibitory ribonucleoprotein but present in cytoplasmic messenger ribonucleoprotein and polysomes.

A cytoplasmic 10S ribonucleoprotein particle (iRNP), which is isolated from chick embryonic muscle, is a potent inhibitor of mRNA translation in vitro and contains a 4S translation inhibitory RNA species (iRNA). The iRNP particle shows similarity in size to the small nuclear ribonucleoprotein (snRNP) particles. Certain autoimmune disease patients contain antibodies directed against snRNP antigenic determinants. The possibility that iRNP may be related to the small nuclear particles was tested by immunoreactivity with monospecific autoimmune antibodies to six antigenic determinants (Sm, RNP, PM-1, SS-A (Ro), SS-B (La), and Scl-70). By Ouchterlony immunodiffusion assays, the cytoplasmic 10S iRNP did not show any immunoreactivity. Also, a more sensitive hemagglutination inhibition assay for detecting Sm and RNP antigens failed to show reactivity with the 10S iRNP. Thus, the 10S iRNP particles are distinct from the similarly sized snRNP. However, free and polysomal messenger ribonucleoprotein (mRNP) particles and polysomes also isolated from chick embryonic muscle and analyzed by Ouchterlony immunodiffusion and hemagglutination inhibition for the presence of the antigenic determinants showed reactivity to Sm and RNP autoantibodies, but were not antigenic for the other four antibodies. Some of the Sm antigenic peptides of mRNP particles and polysomes were identical to those purified from calf thymus nuclear extract, as judged by Western blot analysis. The association of Sm with free and polysomal mRNP and polysomes suggests that Sm may be involved in some cytoplasmic aspects of mRNA metabolism, in addition to a nuclear function in mRNA processing.

Animals↗
PubMed1984

Motility, expression of surface antigen, and X and Y human sperm separation in in vitro fertilization medium.

The influence of surrounding medium on human sperm swimming behavior has been characterized. In modified Ham's F-10 serum-supplemented in vitro fertilization medium, the straight-track swimming pattern of sperm in semen changed rapidly into circular tracks, and a new surface antigen was detected soon after this change. The circular tracks alternated between clockwise and counterclockwise directional movements. Addition of 17 beta-estradiol in a concentration range found in follicular fluid increased the frequency of clockwise movement twofold, suggesting that a steep concentration gradient created by an aduterine flow during ovulation, is likely to direct sperm migration up the gradient in the ipsilateral oviduct. Separation of X and Y sperm raised the possibility that a female carrier of an X-linked disease might choose to have a daughter, instead of taking the chance of having an affected son.

Antibodies, Monoclonal↗
PubMed1984

The cytoplasmic 4S translation inhibitory RNA species of chick embryonic muscle: fractionation of biologically active subspecies by high performance liquid chromatography.

A 4S RNA species (iRNA) isolated from chick embryonic muscle which is a potent inhibitor of mRNA translation in vitro shows heterogeneity in the 70-100 nucleotide size range (Sarkar, S., Mukherjee, A.K., and Guha, C. (1981) J. Biol. Chem., 256, 5077-5086). The iRNA was fractionated by HPLC on different size exclusion columns using a variety of elution conditions. Chromatography of iRNA on a TSK 4000 SW column and elution with a low ionic strength buffer gave three components, one of which contained a pure subspecies of about 90-100 nucleotides size, as shown by a single band on PAGE analysis in 99% formamide. The biological activity of this purified subspecies showed that this is a more potent inhibitor of globin mRNA translation than unfractionated iRNA (Sarkar, S., Mukherjee, A.K., and Guha, C., (1981) J. Biol. Chem. 256, 5077-5086). Partial resolution of three additional low molecular weight iRNA subspecies in the 70-80 nucleotide size range in biologically active form was obtained on chromatography of unfractionated iRNA on TSK 4000 SW column in the presence of 0.5 M NaCl or on TSK 3000 SW column in the presence of low salt. The fractionation of iRNA by HPLC appears to be primarily based on size. These results strongly suggest that HPLC may also be useful for the fractionation of a variety of low molecular weight eukaryotic nuclear and cytoplasmic RNAs with retention of biological activity.

Animals↗