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Biomedical subjects

M Mukhtar

Publications and source records attributed to M Mukhtar.

29 records · Page 2Linked to original sources
PubMed1996

Mechanisms of transcriptional transactivation and restriction of human immunodeficiency virus type I replication in an astrocytic glial cell.

Unique transcriptional transactivation by the human immunodeficiency virus type 1 (HIV-1) Tat protein of long terminal repeat (LTR)-driven RNA expression, in the absence of the transactivator responsive element (TAR), was previously demonstrated in central nervous system (CNS)-derived astrocytic cell-lines, including U87MG. In the present study, RNase protection assays were utilized to reveal the molecular mechanism(s) underlying transactivation of the HIV-1-LTR in these cells. Short transcripts, which represent abortive HIV-1 transcription, could not be detected either in the absence or presence of Tat, and no differences in transcript levels were detected using 5' probes, as compared to 3' probes, in the experiments. Thus, the transactivational effects of Tat, in U87MG cells, were potentially based on the increase of transcriptional initiation, both in TAR-dependent and -independent states. Further, by using newly established stable cellular transformant, containing HIV-1-LTR-reporter gene constructs, TAR-independent transactivation was demonstrated to efficiently function primarily in transiently-transfected U87MG cells. U87MG cells, stably-transfected with the intact HIV-1 proviral genome, produced very low levels of virus after long-term culture, as previously reported in other astrocytic cells. These cells demonstrated profoundly restricted transcription of the HIV-1 genome, with no detectable levels of HIV-1-specific RNA by Northern blotting, indicating that the restriction of viral production in these cells is principally due to the low level of overall transcription from the 5' HIV-1-LTR. Transcription of HIV-1 RNA in this cell could not be significantly up-regulated by various stimulators, such as phorbol 12-myristate 13-acetate (PMA), tumor necrosis factor-alpha (TNF-alpha) and sodium butyrate. These data suggest that the restriction of HIV-1 transcription in these cells may be controlled by different mechanism(s) from those in lymphocytic or monocytic cells.

Astrocytes↗
PubMed1996

Cloning and sequence analysis of a putative transcription factor (MTF1) gene from Mucor circinelloides.

We describe here the fortuitous cloning of a putative transcription factor gene (MTF1) from the dimorphic fungus Mucor circinelloides. Sequence analysis of MTF1 revealed an open reading frame (ORF) of 1059 nucleotides encoding a protein of M(r) 39601. The deduced amino acid sequence from the ORF imparts two glutamine-rich stretches which are homologous to a number of transcription factors characterized previously from various organisms. A Southern blot analysis of Mucor genomic DNA digested with different restriction endonucleases and probed with the 1.9 kb EcoR1 fragment of the putative transcription factor gene shows a single copy number of the the gene. Northern analysis during morphogenetic changes in Mucor suggested constitutive expression of the gene.

Amino Acid Sequence↗
PubMed1996

Evaluation of relative promoter strengths of the HIV-1-LTR and a chimeric RSV-LTR in T lymphocytic cells and peripheral blood mononuclear cells: promoters for anti-HIV-1 gene therapies.

Gene therapy approaches for human immunodeficiency virus type 1 (HIV-1) infections focus on the transfer of critical genetic elements into CD4+ T lymphocytes and CD34+ stem cells. Ideally, expression of the anti-HIV-1 gene constructs should be induced during early stages of infection to combat high turnover of the replicating virus. In this study, we investigated the activity of two promoters, HIV-1 long terminal repeat (HIV-1-LTR) and Rous sarcoma virus (RSV) LTR fused with the transactivation response element (TAR) from the HIV-1-LTR (ie RSV-TAR) in presence of Tat, the major HIV-1 transcriptional transactivator and an early gene product in HIV-1 infection. Comparative expression from both of these plasmids was analyzed by measuring expression of a reporter gene, chloramphenicol acetyltransferase (CAT), after transfection of the promoter-CAT constructs and a Tat-expressing plasmid into CEM T lymphocytic cells and peripheral blood mononuclear cells (PBMC). The HIV-1-LTR could be transactivated by Tat in both unstimulated and stimulated cells. Although the RSV-TAR had a relatively high basal level of expression, Tat transactivation of this chimeric promoter occurred only in unstimulated cells. These results suggest that the HIV-1-LTR may be a better promoter for therapeutic gene expression in anti-HIV-1 intracellular immunization approaches.

Avian Sarcoma Viruses↗
PubMed1992

The carboxypeptidase Y-encoding gene from Candida albicans and its transcription during yeast-to-hyphae conversion.

We have cloned and sequenced the gene (CPY1) encoding the carboxypeptidase Y (CPY) of Candida albicans. The gene contains an open reading frame comprising 542 amino acids (aa) with an M(r) of 61,104. The aa sequence shows 74% identity to the mature CPY aa sequence from Saccharomyces cerevisiae. The putative pre (signal) and pro sequences at the N terminus of the C. albicans protein, however, show significant divergence from the corresponding prepro sequence of the S. cerevisiae protein. Southern analysis of C. albicans genomic DNA suggested the presence of only one CPY-encoding gene. Northern analysis during yeast-to-hyphae conversion suggested that the CPY1 gene is transiently down-regulated on a transcriptional level during the early events of this developmental switch.

Amino Acid Sequence↗
PubMed1991

Health workers' attitudes can create communication barriers.

In Sudan's South White Nile Province the development of a communication strategy for the diarrhoeal disease programme was preceded by the collection of data from community members and health personnel. A majority of health workers had only a limited knowledge of the community's methods of dealing with diarrhoea. Most of these workers had very negative attitudes towards mothers and home interventions. This information was vital for planning a comprehensive educational scheme for both health workers and communities.

Attitude of Health Personnel↗
PubMed1980

Differential effects of cytochrome P450-inducers on promutagen activation capabilities and enzymatic activities of S-9 from rat liver.

Studies have been conducted to determine aryl hydrocarbon hydroxylase, benzphetamine-N-demethylase, epoxide hydrase and glutathione S-transferase activities and cytochrome P-450 content in the liver 9000xg supernatant fractions from rats treated with either phenobarbital, beta-naphthoflavone, ARoclor 1254 or a combination of phenobarbital and beta-naphthoflavone. The metabolic activation of 2-anthramine, 2-acetylaminofluorene, 3-methylcholanthrene, and benzo(a)pyrene to metabolites that are mutagenic in Salmonella typhimurium TA1535 or TA98 by S-9 from rats treated with these inducers was also determined. The induction of drug metabolizing enzymes in the S-9 from Aroclor or phenobarbital plus beta-naphthoflavone treated animals was very similar. The overall results seem to indicate that a combination treatment of phenobarbital and beta-naphthoflavone can be used as a substitute for Aroclor 1254 as inducer for enzyme activity and for the in vitro activation of promutagens to mutagenic metabolites in Salmonella mutagenesis assay systems.

Animals↗
PubMedDate not supplied

Prognostic factors in the management of exacerbation of chronic obstructive pulmonary disease in Kuwait.

OBJECTIVE: To evaluate the clinical presentation and the factors of prognostic importance in the management of exacerbation of chronic obstructive pulmonary disease (COPD). SUBJECTS AND METHODS: One hundred and four patients who were hospitalized because of exacerbation of COPD between 1996 and 2000 were selected for further evaluation. Only patients who fulfilled the American Thoracic Society criteria for diagnosis of COPD were included. The factors examined included age, clinical features, duration of symptoms of exacerbation, severity of underlying disease, comorbid diseases, level of consciousness, previous hospitalization, intubation and assisted ventilation, hypercapnia, degree of acidemia and complications. RESULTS: Seventy-four of 104 (71%) hospitalized patients reviewed met the inclusion criteria for COPD. The mean age was 63.68 +/- 12.6 years. There was a male:female ratio of 3:1. Fifty-eight patients (78%) had a baseline FEV1 <50% before hospitalization and 45 (64%) had previous hospitalization. Comorbid disease was found in 50% of the cases, while 78% had acidemia and 70% hypercapnia. Fourteen (19%) died on admission. Risk factors identified included severity of disease (p < 0.05); presence of comorbid disease (p < 0.01); acidemia (p < 0.0001); hypercapnia (p < 0.0001); previous hospitalization (p < 0.01), and assisted ventilation (p < 0.001). CONCLUSION: This study revealed that the presence of comorbid disease, acidemia, previous hospitalization and assisted ventilation significantly contributed to mortality in patients with exacerbation of COPD.

Aged↗
PubMedDate not supplied

The effect of aluminum on the stromal cells (in vitro) on bone marrow in rats.

The aim of this study was to describe the effects of aluminum on the stromal cells of rat bone marrow using a combination of in vivo exposure and in vitro culture of bone marrow. The toxic effects of aluminum are manifested by a decrease in the erythrocyte count and hemoglobin level in the peripheral blood. Aluminum stimulated an increase in the number of fibroblasts while the macrophage count dropped. The number of adipocytes remained unaffected. An increase in mean corpuscular hemoglobin (MCH) was also found in the peripheral blood of experimental animals.

Aluminum↗
PubMedDate not supplied

Analysis of HIV-1 in the cervicovaginal secretions and blood of pregnant and nonpregnant women.

OBJECTIVES: To detect HIV-1 in cellular and acellular fractions of cervicovaginal secretions obtained by cervicovaginal lavage (CVL) and evaluate viral genotypes in the HIV-1-positive CVL samples. STUDY DESIGN/METHODS: This study consists of 37 HIV-1-seropositive pregnant and nonpregnant women from the United States. A total of 63 paired CVL and blood samples were collected. HIV-1 DNA from cervical cells (CC) and virion RNA from cervical supernatant (CS) was detected by gag polymerase chain reaction (PCR) assays. The HIV-1 genotypes were determined by analyzing the nested PCR-amplified V3 region sequences of the HIV-1 gp120 envelope gene. RESULTS: Within this cohort, 95% of the women were on single or combination antiretroviral therapy. Of the pregnant women, 63% of samples had HIV-1 viral DNA in the CC, and 29% of samples were positive for viral RNA in the CS. Among nonpregnant women, 71% of samples were positive for HIV-1 DNA in CC, and 46% of samples tested positive for virion RNA in CS. Plasma viral load ranged between 10,000 and 100,000 copies/mL and showed significant correlation with the detection of HIV-1 RNA in the CVL; this relation was less apparent with viral DNA in CC. The viral blood and CVL specimens were further analyzed by evaluating the genotypes of HIV-1 variants. In most patients, a high degree of similarity was observed between the viral sequences derived from blood and CVL samples. Two patients demonstrated closely related but somewhat distinct genotypic variants in CVL and blood. One subject showed clear compartmentalization in which distinct viral genotypes were observed in CVL and blood. Based on V3 loop analyses of gp120, with one exception, the cervicovaginal secretions harbored viral populations with a macrophage (CCR5)-tropic phenotype. CONCLUSIONS: This study demonstrates the unique characteris tics of HIV-1 strains in the genital secretions of a relatively large cohort of HIV-1-infected women in the United States. These results are important for further analysis of HIV-1 transmission and pathogenesis in vivo and for rational vaccine design.

Adult↗
PubMedDate not supplied

Development of an in vitro blood-brain barrier model to study molecular neuropathogenesis and neurovirologic disorders induced by human immunodeficiency virus type 1 infection.

OBJECTIVE: An in vitro blood-brain barrier (BBB) system was developed using primary cultures of human brain-derived microvascular endothelial cells (MVECs), macrophages, neuronal cells, and human fetal astrocytes. This BBB system simulates important morphologic and permeability characteristics of the BBB in vivo. This system could be used to study human neurologic/neurovirologic disorders. STUDY DESIGN AND METHODS: Microvascular endothelial cells were cultured to 100% confluency on the upper side of 0.45-microm polyethylene tetraphthalte (PET) membrane inserts coated with MVEC attachment factor. Expression of ZO-1 (Zona Occludens 1), a protein specifically associated with tight junctions and the intercellular sealing of adjacent MVECs, was analyzed by immunocytochemical methods. The integrity of the BBB formed on the insert membrane was also assessed by the measurement of electrical current passage through the membrane; and, after the formation of complete BBB, a two-compartment system was developed using the cell culture insert upper surface, essentially a confluent monolayer of brain-derived MVECs housed on a six-well chamber surface. In the six-well chamber surface, there are different central nervous system (CNS)-based cells, ie, human astrocytes, immature neurons, mature neurons, and MVEC. The cell culture inserts were in close juxtaposition to the surface of the chamber, making an intimate contact with the cells, separated by an insert membrane. The MVEC surface of the insert was exposed to human immunodeficiency virus type 1 (HIV-1) strains 89.6, NL4-3, and IIIB. After 72 hours, the cells were fixed and used for in situ polymerase chain reaction (IS-PCR), whereas the supernatant was subjected to HIV-1 p24 antigen determination. RESULTS: Primary human brain MVECs are capable of forming tight junctions, revealed by the expression of ZO-1, as well as elevated transendothelial electrical resistance. Based on these characteristics, these cells formed an in vitro BBB, which then was used to study the transfer of HIV-1 through this barrier. It was observed that HIV-1 can infect MVEC and can cross it in vitro and infect the cells growing on the opposite side of the membrane. Infection of various CNS-based cells was confirmed by IS-PCR, as well as by HIV-1 p24-antigen determination. It was observed that the dual-tropic strain, 89.6, had a greater potential to create a breach in the in vitro BBB, followed by NL4-3 and IIIB. CONCLUSION: This model system is relevant for evaluating HIV-1 neuropathogenesis and therapeutics designed to alter HIV-1 expression in human CNS-based cells. As such, the effects of highly active antiretroviral therapy on HIV-1 infection of the human CNS, a possible drug sanctuary site, can be evaluated using this technology.

AIDS Dementia Complex↗