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Biomedical subjects

A Hossain

Publications and source records attributed to A Hossain.

At least 55 records · Page 3Linked to original sources
PubMed1995

Identification of cellular protein that can interact specifically with the basic helix-loop-helix domain of the aromatic hydrocarbon receptor.

The Ah receptor is a basic helix-loop-helix (bHLH)-PAS protein and functions as a ligand-activated DNA binding protein directly interacting with target genes by binding to xenobiotic responsive elements. We have sought to identify possible cellular proteins that can interact with the Ah receptor. The bHLH domain of the Ah receptor was fused to glutathione-S-transferase (GST), and the resulting fusion protein was used as a probe to help us to identify receptor associated protein(s). At least one such protein, 45kDa (p45), was detected in mouse liver extracts, but it does not bind to the bHLH domain of the Ah receptor nuclear translocator, nor to the transactivation domain of Ah receptor or GST alone.

Animals↗
PubMed1995

Identification of a 120-kDa protein associated with aromatic hydrocarbon receptor nuclear translocator.

The aromatic hydrocarbon receptor nuclear translocator (ARNT) is a basic helix-loop-helix-PAS protein which forms a heterodimer with aromatic hydrocarbon receptor (AHR), this heterodimer mediating the signal transduction in response to the various xenobiotics such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and directly interacting with target genes by binding to xenobiotic responsive elements. An anti-ARNT antibody was raised in rabbits against the bacterially expressed ARNT of amino acids 21-328 from the N-terminal. Using this antibody, besides ARNT itself, we detected at least one protein, 120 kDa, in the immunoprecipitate of anti-ARNT antibodies in HepG2 cells as well as in Hepa-1 cells. However, this protein is not present in the immunoprecipitate of the anti-AHR antisera nor in that of the preimmune sera of the rabbits used for the immunization.

Animals↗
PubMed1995

Current status of the molecular genetics of hepatitis C virus and its utilization in the diagnosis of infection.

BACKGROUND: Since the discovery of hepatitis C virus (HCV) as a major cause of non-A non-B hepatitis, advances have been made in our understanding of the molecular biology of HCV and its relatedness to the flaviviruses and pestiviruses. The use of molecular techniques to construct an antibody assay has enabled the accumulation of information concerning the natural history and pathogenesis of HCV infection. OBJECTIVES: The objective was to review the literature to March 1994 on the structure, function and genetics of HCV and to correlate these findings with approaches to diagnosis that have contributed to our understanding of HCV infections. STUDY DESIGN: We reviewed the virological and medical literature from 1988 to March of 1994 with a focus on the stated objectives. RESULTS: Although the structure of HCV has been well-defined, our knowledge of the function of all the genes of HCV is incomplete. Structural core and envelope proteins as well as enzymes have been described. The 5' end of the polypeptide is most conserved. Genotyping of isolates varies according to the part of the gene examined. Several genotypes exist and tend to predominate in global populations. Antibodies to the various proteins can be measured by EIA assays and positive specimens often require confirmatory testing. Uniquely sensitive nucleic acid detection systems for RNA amplified by PCR have enabled a better understanding of the natural history, epidemiology and responses to treatment. CONCLUSIONS: Well-designed studies for the detection of nucleic acid, antibodies and antigens using a variety of viral gene products will provide even more information about HCV infections and help lead to treatment and prevention.

Journal Article↗
PubMed1995

Profile of hepatitis C virus and the possible modes of transmission of the virus in the Gizan area of Saudi Arabia: a community-based study.

The seroprevalence of antibody to hepatitis C virus (anti-HCV) and the possible modes of transmission of HCV were investigated in Gizan, southern Saudi Arabia. The sample size chosen to give an adequate estimate of the seroprevalence, about 1500, was based on the assumption that 5% of the population in Gizan were anti-HCV-positive. Sera from 1482 subjects (705 males, 777 females; aged > or = 10 years) were initially screened for anti-HCV using a commercial, ubiquitin-based enzyme immunoassay. Repeatedly reactive sera were confirmed positive using second-generation immunoassays. Serum samples were also tested by ELISA for hepatitis B surface antigen (HbsAg) and antibodies to this antigen and to the hepatitis B core antigen. Of the subjects tested, 27 (1.8%) were anti-HCV-positive. Exposure to HCV was generally similar in both sexes, age-prevalence curves for anti-HCV peaking in males aged > 49 years (6.2%) and in females aged 40-49 years (5.0%). In the youngest subjects, those aged 10-19 years, the HbsAg carrier rate was significantly higher in males (10.4%) than in females (3.6%). Exposure to the hepatitis B virus was similar in both sexes (31.0% in males v. 28.6% in females). Some 7.4% and 14.8% of the 27 anti-HCV-positive cases had histories of schistosomiasis and blood transfusion, respectively. The corresponding values for the 1455 anti-HCV-negative cases investigated, 1.1% for schistosomiasis and 3.5% for blood transfusion, were much lower. The spouses and other family members of eight anti-HCV-positive index cases were investigated but none was anti-HCV-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Assessment of cancer susceptibility in humans by use of genetic polymorphisms in carcinogen metabolism.

Prevention is an important and effective measure for reducing death caused by cancer. Thus information on individual susceptibility to cancer is valuable in suggesting high risk individuals to avoid intake of carcinogenic substances and receive frequent physical screening. To this end, polymorphisms found within cytochrome P450 (CYP) genes implicated in the metabolism of procarcinogens are expected to be good genetic targets in assessing human cancer susceptibility. We have found polymorphisms in the CYP2E1 and CYP1A1 genes associated with lung cancer susceptibility, though there were some discrepancies from observations made by other investigators. Discrepancies among investigators from different regions, however, are very common in these pharmacogenetic studies. We present an explanation for these discrepancies, difficulties associated with prediction of relative risk of individuals, and future directions.

Carcinogens↗
PubMed1995

Identification of gene products encoded by the latency-related gene of bovine herpesvirus 1.

Bovine herpesvirus 1 (BHV-1) establishes a latent infection in sensory ganglionic neurons of infected animals. Expression of latency-related (LR) gene products is controlled by a 980-bp fragment (LR promoter). DNA sequence analysis revealed that two major open reading frames (ORFs) are in the LR gene. Antibodies directed against both ORFs were generated in rabbits by using synthetic peptides. Antibody P2, which is directed to sequences near the amino terminus of ORF 2, recognized a 41-kDa protein in lytically infected cells, suggesting that ORF 2 encodes a protein. When the LR gene was inserted into a mammalian expression vector and subsequently transfected into COS-7 cells, a 41-kDa protein was detected by use of silver-stained sodium dodecyl sulfate-polyacrylamide gels and by the P2 antibody. In contrast, this protein was not detected in mock-transfected cells. Deletion of DNA sequences containing ORF 2 blocked synthesis of the 41-kDa protein in COS-7 cells. Reverse transcriptase-mediated PCRs indicated that splicing occurs near the C terminus of ORF 2. Further studies indicated that LR RNA was alternatively spliced in latently infected cattle and that a fraction of LR RNA was poly(A)+. Taken together, these studies suggested that a spliced LR transcript has the potential to encode a 41-kDa protein.

Amino Acid Sequence↗
PubMed1994

Effect of rate of intracellular transport and diacytosis on cytotoxicity of hybrid toxins. Study with hybrids using hepatic asialoglycoprotein receptor-mediated endocytosis.

The effects of diacytosis and intracellular transport rate on cytotoxicity of hybrid toxins were studied with conjugates of diphtheria toxin fragment A (DTA) to asialoorosomucoid (ASOR) and its reduced and carboxymethylated cyanogen bromide fragment I (RC-ASCNBr-I) in cultured rat hepatocytes. In the hepatocytes the kinetics of uptake of the conjugate of asialoorosomucoid (DTA-ASOR) and that of the conjugate of the cyanogen bromide fragment (DTA-RC-ASCNBr-I) were quite similar, but the rate of accumulation of DTA moiety into the lysosomes, as determined by Percoll density gradient centrifugation, was found to be greater for the latter than the former. However, after internalization, DTA-RC-ASCNBr-I was diacytosed to a lesser extent than that of DTA-ASOR, particularly when colchicine was present during internalization. Analysis of the subunits of DTA-ASOR internalized by the hepatocytes indicated that they were accumulated disproportionately in a time-dependent manner so that the glycoprotein moiety was accumulated progressively more than the toxin moiety. Cytotoxicity of DTA-ASOR toward the hepatocytes was 2-times as much as that of DTA-RC-ASCNBr-I. Colchicine enhanced the toxicity of DTA-RC-ASCNBr-I (33-fold) to a greater extent than that of DTA-ASOR (12-fold). The difference in enhancement by colchicine was also observed in the rate of cell intoxication by the conjugates. Both conjugates were more toxic to the hepatocytes after incubation with the cells at 18 degrees C than at 37 degrees C. In the presence of vanadate (0.2 mM), which enhanced diacytosis, toxicity of DTA-ASOR decreased by 5-fold. After incubation with the hepatocytes, a partial dissociation of DTA-ASOR was found to occur independently of the receptor-mediated endocytosis. Taken together, these results indicate that diacytosis, subunit dissociation and rapid transport of conjugate toward lysosomes affect kinetically the rate of accumulation of the conjugate into a yet unidentified compartment of toxin translocation.

Animals↗
PubMed1994

Hearing impairment among children in Saudi Arabia: familial incidence and potential risk factors.

A comprehensive clinical and laboratory study was carried out to elucidate the aetiology, risk factors, and familial incidence of hearing impairment. The study involved 1072 children at risk for hearing impairment as well as 17 families. Evaluation of the mothers' clinical histories/findings suggested that the leading possible risk factors for hearing impairment in children were frequent pregnancies, miscarriages and low birth weight. Hearing and/or speech problems in siblings, parents, or even grandparents, were noted to be of significance in hereditary transmission. Among 42 clinically-diagnosed and laboratory confirmed cases, the aetiologic agent found to occur most frequently was, unusually, herpes simplex virus type 1, a non-TORCH agent. Second in frequency of occurrence was Toxoplasma gondii. There was IgM positivity for multiple agents including rubella virus with cytomegalovirus. In the family study, a reliable laboratory confirmation of clinically-diagnosed hearing impairment was obtained in 10-17 families (58.8%). An interesting finding, and one which concurred with clinical histories/findings, was that the incidence of hearing impairment could be reliably correlated with high positivities to IgG, particularly cytomegalovirus.

Child↗
PubMed1994

Diarrhea associated with Cyclospora Sp. in Bangladesh.

A spherical acid-fast organism measuring approximately 10 microns in diameter (Cyclospora sp.) has recently been implicated in diarrheal diseases in many parts of the world. We detected this organism in the stools of six Bangladeshi patients with diarrhea. Four patients had chronic diarrhea and two had acute diarrhea at the time of presentation. This is the first report of infection with this organism in the indigenous population from this region.

Adult↗
PubMed1994

Monoclonal antibodies specific for Shigella dysenteriae serotype 13. Production, characterization, and diagnostic application.

Three mouse monoclonal antibodies (mAbs) (ICL3, ICL4, and ICL5) were produced that specifically recognized the lipopolysaccharide antigen of the newly recognized Shigella dysenteriae serotype-13 strain. All three mAbs reacted with all nine reference isolates of S. dysenteriae 13 in different tests. The mAbs also detected colonies of S. dysenteriae-13 isolates by direct slide agglutination test. The mAbs also reacted with the reference Escherichia coli 0150 strain and showed its close antigenic relationship with S. dysenteriae 13. Use of these mAbs in our clinical laboratory during an 8-month period detected three S. dysenteriae-13 isolates that were also detected by a polyclonal rabbit antiserum. It should now be possible to define the epidemiologic importance of S. dysenteriae serotype 13 in diarrhea by using these mAbs.

Agglutination Tests↗
PubMed1994

Differential c-jun gene expression with tonically administered steroids in rat ovary and uterus.

OBJECTIVE: The purpose of this study was to evaluate the induction of the early regulatory gene c-jun in response to tonic exposure to estradiol and progesterone in rat ovary, uterus, and adrenal tissues. STUDY DESIGN: Pellets containing estradiol-17 beta, progesterone, and estradiol-17 beta plus progesterone were placed subcutaneously in immature female Sprague-Dawley rats (N = 24). The ovary, uterus, and the adrenal were evaluated for c-jun expression by Northern analysis at 24 and 48 hours. RESULTS: The c-jun messenger ribonucleic acid expression in the ovary and adrenal gland was inhibited with high, nonphysiologic doses of estradiol in progesterone and was induced with physiologic levels of estradiol. Physiologic levels of progesterone do not appear to influence the expression of c-jun in the ovary or adrenal gland. Uterine c-jun expression to estradiol and progesterone is generally the opposite of that observed in the ovary. CONCLUSION: These findings suggest that there is both tissue and dose specificity of c-jun gene expression in steroidogenic and steroid-responsive tissues when steroid hormones are tonically administered.

Adrenal Glands↗
PubMed1994

Androgenic modulation of lipid metabolism at subcellular sites in cholestatic rats.

The present studies examine the modulation of lipid metabolism at subcellular sites in the liver of control and cholestatic rats by a male sex hormone. Subcutaneous injection of testosterone enanthate (5 mg/kg body weight), increased triacylglycerol lipase (TG-lipase) and neutral cholesterol ester hydrolase (CE-hydrolase) activity in endosomes of normal rats. During induced cholestasis, TG-lipase and CE-hydrolase activity in endosomal fractions were decreased compared to those in endosomes of age-matched sham-operated female controls. Following testosterone administration to cholestatic rats, endosomal lipolytic enzyme activity increased to approximate the levels of normal controls. These observations may provide insight into the alterations in lipid metabolism which accompany cholestatic liver disease.

Animals↗
PubMed1994

Production of slime polysaccharides by Shigella dysenteriae type 1.

Electron microscopy of ruthenium red-stained ultrathin section of strains of Shigella dysenteriae type 1 grown in the Casamino Acids-yeast extract broth medium showed the presence of an extracellular slime layer. The slime appeared as a dense sheath covering bacteria. The presence of slime promoted hemagglutinating activity of the bacteria. The slime polysaccharide (SPS) isolated from the cell-free culture supernatant or the bacterial surface was less than 162,000 daltons in size and immunochemically similar. The SPS showed cross-reaction with lipopolysaccharide (LPS) antigen in immunological tests; however, it also appeared to be different from LPS since it did not contain 2-keto-3-deoxyoctonate, a core sugar of LPS. A different pattern of separation from LPS was also observed by silver staining of SDS-polyacrylamide gels. From these data it appeared that either LPS and SPS are contaminated with each other or that SPS is the polysaccharide portion of LPS.

Animals↗
PubMed1994

Effect of antibiotics on serum bactericidal action on Plesiomonas shigelloides by normal human serum.

Thirteen clinical isolates of Plesiomonas shigelloides were tested for antibiotic susceptibility of tetracycline, kanamycin-sulphate, gentamicin, erythromycin and ciprofloxacin. All the strains were susceptible to all these antibiotics. The minimal inhibitory concentration (MIC) of all these antibiotics were: Kanamycin-sulphate-MIC 0.4-10.0 micrograms/ml, tetracycline-MIC 0.25-2.4 micrograms/ml, gentamicin-MIC 2.0-12.0 micrograms/ml, erythromycin-MIC 0.5-14.0 micrograms/ml and ciprofloxacin-MIC < or = 0.006 micrograms/ml. The MIC and MBC (minimal bactericidal concentration) of the antibiotics kanamycin-sulphate, tetracycline, gentamicin, erythromycin and ciprofloxacin changed little in the presence of serum protein. Different concentrations of sub-MICs played synergistic role in serum bactericidal action on this organism.

Anti-Bacterial Agents↗
PubMed1993

A monoclonal antibody to Shigella dysenteriae serotype 13 cross-reacting with Shiga toxin.

A monoclonal antibody (mAb ICT6) was produced against the newly described Shigella dysenteriae serotype type 13. The mAb was of IgM isotype and recognized purified Shiga toxin in ELISA and immunoblot. It also recognized periplasmic extract S. dysenteriae type 13 in immunoblot as did an affinity-purified polyclonal rabbit antiserum and a previously described monoclonal antibody to the B subunit of Shiga toxin. The mAb ICT6 did not neutralize the cytotoxic effects or S. dysenteriae type 13, Shiga toxin or periplasmic extracts of S. dysenteriae type 1 for HeLa cells.

Animals↗
PubMed1993

Role of Shigella dysenteriae type 1 slime polysaccharide in resistance to serum killing and phagocytosis.

Shigella dysenteriae type 1 produce a slime polysaccharide when cultivated in vivo in adult rabbit ileal loops or in vitro in casamino acid yeast extract broth medium which promotes hemagglutination of these bacteria. Seven strains of S. dysenteriae 1 grown in vitro and in vivo and possessing slime polysaccharides resisted killing by normal human serum as compared to bacteria grown under conditions which do not stimulate the production of capsular polysaccharide and did not resist serum killing (mean survival 72% for in vitro growth and 73% for in vivo growth conditions favoring capsule production vs < 2% for growth conditions which do not favor capsule production; P < 0.001 for both comparisons). Similar differences were observed when killing was assessed by phagocytosis (62-78% vs < 2%; P < 0.001). We conclude that capsular polysaccharide may be an additional virulence factor of S. dysenteriae 1.

Animals↗