Biomedical subjects

S Jameel

Publications and source records attributed to S Jameel.

44 records · Page 3Linked to original sources

PubMed1986

Transcriptional control elements of hepatitis B surface antigen gene.

A series of recombinant plasmid vectors containing hepatitis B virus (HBV) DNA sequences was constructed to study the biosynthesis of the hepatitis B virus surface antigen (HBsAg) RNA and to locate transcriptional control elements involved in the regulation of the S and pre-S DNA sequences. We examined the transcription of the HBsAg gene in permanent cell lines that were developed by transfecting with recombinant vectors containing HBV sequences and the neomycin gene followed by G418 selection. We further defined the promoter activities upstream of and within the pre-S sequences using the assayable chloramphenicol acetyltransferase gene. Results obtained from S1 nuclease digestion and primer extension suggest that HBsAg transcripts are initiated at multiple sites in the pre-S region and from a site upstream of the pre-S region. Chloramphenicol acetyltransferase assays indicate that DNA sequences within and upstream of the pre-S region contain promoter activities and that the "TATA" sequence-containing promoter and the internal promoter show similar levels of activities in CV-1 cells and several other cell lines tested.

Animals↗

PubMed1986

The human hepatitis B virus enhancer requires trans-acting cellular factor(s) for activity.

The activity of the hepatitis B viral enhancer element was studied in various cell lines. This enhancer shows strict host and tissue specificity in that it is functional only in liver cells of human origin. Further, it requires trans-acting factor(s) present in liver cells for activity, and this activity is independent of hepatitis B virus gene products in the cell lines tested.

Acetyltransferases↗

PubMed1986

Expression of hepatitis B viral core region in mammalian cells.

We studied the expression of the core region of the hepatitis B virus genome in mammalian cells with recombinant plasmid vectors. Stably transformed rat fibroblast cell lines were established by transfection with vectors containing subgenomic and genome-length hepatitis B virus DNA, followed by G418 selection. The RNA transcripts directed by the core region were characterized by Northern blot hybridization and S1 nuclease mapping. Using the chloramphenicol acetyltransferase gene expression system, the promoter activity located upstream of the core open reading frame was confirmed. The synthesis of core and e polypeptides was studied with a commercial radioimmunoassay. These studies show that partial deletion of the precore sequences abolished secretion of the e antigen, but there was pronounced synthesis of the core antigen in transfected cells.

Animals↗

PubMed1985

Modification of the active site of isocitrate lyase from watermelon cotyledons.

Isocitrate lyase (EC 4.1.3.1) from watermelon cotyledons was modified by diethylpyrocarbonate and by the affinity labels 3-bromopyruvate and itaconate epoxide. The reaction with diethylpyrocarbonate, carried out at 30 degrees C in sodium phosphate, pH 6.5, modified (per subunit) 5 histidines in the absence and 4 in the presence of substrate. The kinetics were nonsaturating with respect to diethylpyrocarbonate and the enzyme was protected against modification by substrate or both products together. Hydroxylamine (0.5 M) reversed both histidine modification and inactivation. The reaction with 3-bromopyruvate, carried out at 30 degrees C in 4-morpholinepropanesulfonic acid, pH 7.7, modified (per subunit) 1 sulfhydryl in the absence and 0 in the presence of substrate. The reaction showed saturation kinetics (KBrP = 1.4 X 10(-5)M) and Ds-isocitrate offers competitive protection (KI = 0.2-0.3 mM; Km = 0.25 mM). The reaction with itaconate epoxide, carried out at 30 degrees C in sodium phosphate, pH 7.0, was also saturating (KItEp = 16.4 mM) and the reversible inhibitor, itaconate (KI = 50 microM; Ki = 22.5 microM) as well as the product, succinate (KS = 10.4 mM; Ki = 4.5 mM) offer competitive protection. Hydroxylamine (1 M, pH 7.0) reversed inactivation of the enzyme, indicating modification of a carboxylate residue at the active site. In summary, three different amino acid residues have been modified in the active site domain of watermelon isocitrate lyase.

Affinity Labels↗

PubMed1985

Caenorhabditis elegans: purification of isocitrate lyase and the isolation and cell-free translation of poly(A+)RNA.

Isocitrate lyase (EC 4.1.3.1) from mixed larval populations of Caenorhabditis elegans was stabilized in crude extracts by centrifugation over a 0.2-0.6 M sucrose gradient for 2.5 hr in a vertical rotor (VTi 50) at 210,000g. The peak fractions from this sucrose gradient showed a half-life of 33 hr at 30 C and 225 hr at 4 C in contrast to 2.5 and 52 hr, respectively, for the crude extract. A purification scheme involving (NH4)2SO4 precipitation and chromatography on Sepharose 6B and diethylaminoethyl-cellulose yielded isocitrate lyase that gave one band after electrophoresis in a sodium dodecyl sulfate-gel polymerized from 12% acrylamide. The purified enzyme with a molecular weight of 250,000 and subunit molecular weight of 61,600, had a specific activity of 2 mumoles glyoxylate formed min-1 mg protein-1, and was obtained in a 4% yield. Isocitrate lyase from C. elegans lost 80-85% of its activity in the precipitation by 33-55% (NH4)2SO4, but this step appeared to be necessary for purification to homogeneity. The use of fast protein liquid chromatography appeared to be promising in that it provided an enzyme preparation that was about 50% pure with a specific activity as high as 3 mumoles glyoxylate formed min-1 mg protein-1. Poly(A+)RNA was isolated from C. elegans and translated in wheat germ cell-free system. Analysis on a 10% sodium dodecyl sulfate-polyacrylamide gel showed varied translation products including one or more 60,000-Da polypeptides.

Caenorhabditis↗

PubMed1984

Gel electrophoretic profiles of proteinases in dark-germinated flax seeds.

The proteinases present in dark-germinated flax seeds (Linum usitatissimum) were studied as a function of germination at 25 degrees C. A majority of activity was present in basic proteinases with an acidic pH optimum and a temperature optimum of 45 degrees C in the digestion of hemoglobin. Electrophoresis in a sodium dodecyl sulfate-polyacrylamide mixture which had been polymerized with gelatin was used to separate proteins in extracts of seedlings. Subsequent activation of proteinases with Triton X-100 and resultant digestion of gelatin proved to be very reproducible and afforded detection and good quantification of various proteinase zones. An ethylenediaminetetraacetate-sensitive proteinase zone, P4 (about 60,000 daltons), appeared at day 3 after imbibition and attained maximum activity at day 4. This correlates with a rapid loss in vivo of the glyoxysomal enzyme, isocitrate lyase (EC 4.1.3.1). Ethylenediaminetetraacetate also slowed the loss of isocitrate lyase activity in extracts of 4-day seedlings in a dose-dependent manner. The addition of leupeptin, alpha-tolylsulfonyl fluoride, Pepstatin A, p-chloromercuribenzoate, or 1,10-phenanthroline prior to, during, or after exchange of Triton X-100 for sodium dodecyl sulfate had almost no inhibitory effect upon proteinases in 4-day seedlings.

Journal Article↗

PubMedDate not supplied

The epidemiologic significance and clinical pattern of HCV induced chronic hepatitis in India.

Hepatitis C virus (HCV) ribonucleic acid (RNA) was tested for in a group of 16 defined non-B chronic hepatitis patients using specific reverse transcription polymerase chain reaction (RT-PCR). These were chosen from amongst 56 biopsy proven cases of chronic hepatitis of which majority (40) were positive for hepatitis B virus infection. Hepatitis C virus RNA could be demonstrated in 12 (75%) of remaining 16 cases. These include all seven patients positive for antibody to HCV. Two of these patients had past history of blood transfusion and in another two the clinical course started with severe acute liver disease. This study establishes the association of HCV with severe liver disease. The clinical and biochemical profiles are also discussed. In view of limited sensitivity of the antibody assays it is justified to develop diagnostic testes based on local strains.

Adolescent↗

PubMedDate not supplied

Chronic hepatitis in a large Indian hospital.

BACKGROUND: In developed countries as well as in Southeast Asia, the hepatitis B and C viruses are the main causes of chronic hepatitis. In India, however, there have been no major investigations on the aetiology of chronic hepatitis. (The hepatitis E virus which is responsible for half the sporadic and most of the epidemic cases of acute viral hepatitis in India does not cause chronic disease.) We, therefore, studied the profile of chronic hepatitis in India. METHODS: The clinical presentation, aetiology, serology and histological changes were studied prospectively in 48 patients with chronic hepatitis admitted to the All India Institute of Medical Sciences, New Delhi. Of these, 44 (92%) had chronic active hepatitis, 3 (6.3%) had chronic persistent hepatitis and 1 (2%) had chronic lobular hepatitis. RESULTS: The hepatitis B virus was the aetiological agent in 24 (50%) of these patients, the hepatitis D virus in association with hepatitis B virus in 10 (21%), the hepatitis C virus in 7 (15%) and the non-A, non-B viruses other than the hepatitis C virus in 6 (13%). One patient (2.0%) had autoimmune chronic active hepatitis. Jaundice at presentation was seen in 33 (69%) patients and more than half had hypoalbuminaemia (< 3 g/dl) with a prolonged prothrombin time. Alanine aminotransferase levels were less than 5 times above normal in over two-thirds of the patients. The highest alanine aminotransferase values were observed in patients with hepatitis D virus infection whereas the lowest were seen in patients with non-A, non-B related chronic active hepatitis. Histological examination revealed bridging necrosis in 40 (91%) patients with chronic active hepatitis indicating a severe form of disease. Replication of the hepatitis B virus was seen in 13 patients with chronic hepatitis, 5 of whom had hepatitis D virus-induced chronic hepatitis. Patients with hepatitis B virus replication had higher alanine aminotransferase values and more severe bridging necrosis than patients who did not have replicating viruses. Higher alanine aminotransferase values, ascites and oesophageal varices were encountered more frequently in patients with hepatitis B and D virus than in those with non-A, non-B related chronic hepatitis. CONCLUSION: Chronic hepatitis is not uncommon in India. It presents with evidence of severe disease and, as elsewhere, is most frequently caused by the hepatitis B virus.

Adult↗