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Biomedical subjects

S Ali

Publications and source records attributed to S Ali.

At least 181 records · Page 10Linked to original sources
PubMed1997

Synthetic DNA-based genetic markers reveal intra- and inter-species DNA sequence variability in the Bubalus bubalis and related genomes.

A series of synthetic oligonucleotide probes were developed as markers for genetic analysis and molecular systematics of Bubalus bubalis and other eutherian mammals. A very high level of heterozygosity (approximately 95%) was observed in the bubaline genome, with an overall band-sharing probability of 2.08 x 10(-11) using (TGG)6 and Hinf I probe-enzyme combination. Breed affiliation studies on different buffalo breeds, viz. Toda, Surti, Mehsana, and Murrah, revealed that the semiwild Toda breed belonged to a distinct group. The desired genotypes in each successive generation in an actual breeding program were also identified by employing a DNA fingerprinting approach using these markers. Estimation of genetic distances by calculating the mean allelic frequencies at (CA)n, (TGG)n, and (GGAT)n repeat loci between buffalo and other related animals such as horse (order Perisodactyla), rabbits (order Lagomorpha, (pigs, cattle, goat, and sheep (order Artiodactyla) revealed that with respect to the genetic distance coefficient (GDC), goat (caprine) was closer to buffalo (GDC = 0.0005) than sheep (ovine) (GDC = 0.0007). The genetic distance between horse and buffalo was calculated to be 0.4085, indicating that compared to other animals, horse was distantly related to buffalo. The understanding of overall allelic variations and breed affiliation of the bubaline genome will contribute to the propagation and conservation of the desired germ plasm and better management of this species.

Alleles↗
PubMed1997

Relative performance of different types of passive dosimeters employing solid state nuclear track detectors.

Radon and its progeny, known to be carcinogenic, are a matter of great concern in underground mines and energy conserved air-tight houses. Different shapes of dosimeters using solid state nuclear track detectors (SSNTDs) have been devised to measure radon concentrations in mines and dwellings. Sometimes intercomparison of results is required by various laboratories working with solid state nuclear track detector-based passive dosimeters. The present work includes the determination of various parameters for a set of dosimeters consisting of (1) box-type, (2) pen-type, (3) tube-type, (4) Karlsruhe Diffusion Chamber, and (5) bare-type dosimeters. In this research two types of plastics, allyl-diglycol-carbonate (C12H18O7) and cellulose nitrate (C6H8O8N2) known as CR-39 and CN-85, respectively, have been employed. The detection efficiency for alpha particles from radon and its progeny for CR-39 and CN-85 have been compared. All experiments have been carried out in a custom-designed exposure chamber connected to a radon source. The calibration factors, in terms of Bq m(-3) per unit track density (1.0 cm(-2)) with respect to box-type dosimeter, have been determined for intercomparison and standardization of measured radon concentrations by a set of passive radon dosimeters used in various laboratories of the world.

Collodion↗
PubMed1997

Adenosine receptor-mediated relaxation of rabbit airway smooth muscle: a role for nitric oxide.

In this study, we investigated the relaxant effect of adenosine receptor agonists on KCl-precontracted airway smooth muscle from rabbits and characterized the type of receptor involved in bronchorelaxation in the presence and absence of epithelium. We further defined the role of epithelium-derived relaxing factor, i.e., nitric oxide (NO), on these responses. In both epithelium-intact and -denuded tertiary airway rings from rabbits, the adenosine receptor agonists 2-[p-(2-carboxyethyl)]phenylethylamino-5-N'-ethylcarboxamidoadenos ine (CGS-21680), 5'-(N-ethyl-carboxamido)adenosine (NECA), 2-chloroadenosine (CAD), and (-)-N6-(2-phenylisopropyl)adenosine (R-PIA) relaxed airway smooth muscle with a potency order of CGS-21680 > NECA > CAD > R-PIA. A 98.5, 89.7, 73.2, and 64.7% relaxation was observed at 10(-5) M by CGS-21680, NECA, CAD, and R-PIA in the epithelium-intact bronchial rings, respectively. The 50% maximum effective concentration (EC50; x 10(-7) M) values for CGS-21680, NECA, CAD, and R-PIA were 2, 4, 9, and 80, respectively. Denuded rings, however, showed much less relaxant responses to various adenosine agonists compared with epithelium-intact rings. The adenosine receptor antagonist 8-(sulfophenyl)theophylline significantly attenuated the relaxant responses to all the agonists in the epithelium-intact and -denuded rings. The epithelium-dependent relaxant effect of the agonists in airway rings was inhibited by NG-monomethyl-L-arginine (L-NMMA; 30 microM). The EC50 (x 10(-6) M) values for CGS-21680, NECA, CAD, and R-PIA in the presence of inhibitor were 5.5, 8, 30, and 200, respectively. The L-NMMA produced an insignificant inhibitory effect in the epithelium-denuded rings. L-Arginine but not D-arginine (100 microM) reversed the inhibitory effect of L-NMMA on adenosine agonist-induced relaxation. In primary epithelial cells in culture, CGS-21680 (10(-5) M) induced a fourfold increase in NO production over the control. The CGS-21680-induced NO production in epithelial cells was significantly inhibited by NG-nitro-L-arginine methyl ester (L-NAME). Moreover, L-arginine reversed the inhibitory effect of L-NAME in the epithelial cells. The data suggest that adenosine relaxes rabbit airway smooth muscle through an A2 adenosine receptor and the epithelium serves as a source of NO.

2-Chloroadenosine↗
PubMed1997

Differences in follow-up visits between African American and white Medicaid children hospitalized with asthma.

Asthma-related hospitalizations and mortality have risen at alarming rates in the past two decades, taking a disproportionate toll on African American children. Adverse asthma outcomes have been attributed to inadequacies in primary care, raising concerns about the quality of primary care delivered to African American children. To assess differences in care between African American and white children, the authors identified 500 children enrolled in Massachusetts Medicaid and hospitalized for asthma, and reviewed their medical claims data for the six-month period after hospitalization. It was found that African American children had significantly fewer primary care visits than their white counterparts, even after adjusting for potential confounding variables. In contrast, emergency service utilization did not differ by race. The authors conclude that racial disparity exists in primary care access among children with asthma. Interventions should be designed to target poor African American children who suffer disproportionately from this life-threatening yet treatable disease.

Adolescent↗
PubMed1997

[Leiomyosarcoma of the small intestine].

Leiomyosarcomas of the small bowel are quite rare. These tumors are mostly located in the jejunum distal of the duodeno-jejunal flexure. The non-metastasizing leiomyosarcomas have a good prognosis, according to the literature. The adequate surgical treatment is the resection of the small bowel. Chemotherapy is discussed if there is evidence of metastatic disease. For the diagnosis of leiomyosarcomas tumor markers have no significance. We report the case of a 79 years old patient with a leiomyosarcoma of the jejunum who was admitted as an emergency with an acute abdomen and underlying chronic anaemia. This case demonstrates the often unspecific symptoms and characteristics of leiomyosarcomas.

Aged↗
PubMed1997

Blastomycotic osteomyelitis of the pelvis: a case report.

Blastomycosis dermatitis is an unusual fungal infection that can become a diagnostic dilemma if a high index of suspicion is not maintained in patients who present with a chronic granulomatous infection of bone and soft tissue. We present a patient with a long history of pain, systemic manifestations of chronic infection, a draining sinus, and lytic changes on plain films to illustrate the difficulty in establishing the diagnosis. Appropriate staging studies and a bone biopsy led to the correct diagnosis in the patient.

Adult↗
PubMed1997

Training for audit.

Explore the source record for details and available documents.

Education, Medical, Graduate↗
PubMed1996

Nitric oxide is a mediator of methamphetamine (METH)-induced neurotoxicity. In vitro evidence from primary cultures of mesencephalic cells.

METH is a monoaminergic toxic that destroys dopamine terminals in vivo. Oxidative mechanisms associated with DA metabolism are thought to play an important role in its toxic effects. These ideas were supported by the demonstration that CuZn-superoxide dismutase (CuZnSOD) transgenic mice were protected against the toxic effects of the drug. In the present study, we sought to determine if nitric oxide (NO) production was also involved in METH-induced neurotoxicity using primary cultures obtained from fetal rat mesencephalon. METH caused dose- and time-dependent cell death in vitro. Blockade of nitric oxide (NO) formation with several nitric oxide (NO) synthase blockers attenuated METH-mediated toxicity. Moreover, inhibition of ADP-ribosylation with nicotinamide and benzamide also provided protection against the toxicity of the drug. These results, together with our previous results in transgenic mice, support a role for free radicals in METH-induced toxic effects.

Animals↗
PubMed1996

Characterization of a human alphoid satellite DNA sequence: potential use in assessing genetic diversity in Indian populations.

Sequence analysis of a human repetitive DNA sequence (pTRF5.6) revealed considerable homology (76%) to the alphoid consensus sequence. Genomic blots of StuI-digested human DNA, hybridized to pTRF5.6, generated a ladder of bands with each band corresponding to oligodeoxyribonucleotide of an approx. 170-bp repeat, indicating a tandemly arrayed organization of this repeat element within the genome. Genomic hybridization analyses of unrelated individuals belonging to various geographical regions of India, using this alphoid satellite prove, revealed polymorphic bands ranging between 2 and 9 kb. Along with an individual-specific band pattern, several isomorphic bands below 2 kb were also evident. There was very little genetic variability between populations, suggestive of low polymorphism at the inter-population level. Our result suggest that alphoid satellite sequence probe can be used in assessing the genetic diversity of various ethnic groups/populations belonging to different geographical regions.

Base Sequence↗
PubMed1996

Gamma-ray activity and dose rate of brick samples from some areas of North West Frontier Province (NWFP), Pakistan.

It is important to measure natural radioactivity due to gamma-rays from building materials and consequently to determine the dose rate from these materials. This helps to implement precautionary measures whenever the dose rate is found to be above the recommended limits. A knowledge of gamma radioactivity is required by the building construction association to adopt preventive measures to mitigate or minimize the harmful effects of ionizing radiation. The aim of this work was to measure the gamma activity due to 226Ra, 232Th and 40K in bricks from the Peshawar, Nowshera and Mardan districts of NWFP of Pakistan. The radiological doses to the occupants from the brick floor of a wooden house were calculated. The average gamma dose equivalent rate was calculated to be 0.14 mSv per year, which is well below the external gamma dose limit of 0.46 mSv per year as given in UNSCEAR [2].

Background Radiation↗
PubMed1996

Comparison of the EBNA1 proteins of Epstein-Barr virus and herpesvirus papio in sequence and function.

The EBNA1 protein of Epstein-Barr virus (EBV) supports replication and maintenance of the circularized viral chromosome in cells that are latently infected. We have isolated, sequenced, and functionally characterized the EBNA1 gene of herpesvirus papio (HVP), an EBV-like virus that infects baboons. The amino acid sequences of EBNA1 of HVP and EBV are 56% identical, if the difference in the length of the glycine and alanine containing repetitive region, which is much shorter for HVP EBNA1, is omitted for the calculation. The key structural features of the DNA-binding/dimerization domain (the carboxyl-terminal domain) appear to have been conserved, as have amino acids in the two regions thought to be most critical for DNA binding. Most of the salient features of the amino-terminal two-thirds of EBNA1 (the amino-terminal domain), including a dearth of sequences predictive of alpha-helical or beta-sheet structures, are shared by the two sequences, although numerous gaps in this region were needed for alignment of the sequences. The amino-terminal fifty amino acids of EBNA1 of both EBV and HVP weakly resemble the amino terminus of rat ribosomal protein S2. Plasmids carrying oriP of either virus replicated stably in mammalian cells and supported efficient outgrowth of colonies under selection when supported by EBNA1 from either virus, although with each oriP there was a noticeable preference for EBNA1 to be from the same virus. HVP EBNA1 was less effective than EBV EBNA1 at activating the enhancer function of EBV oriP and under certain conditions was less effective than EBV EBNA1 at supporting maintenance of plasmids carrying EBV oriP. Results obtained with hybrid EBNA1 molecules indicated that differences in the amino-terminal and carboxyl-terminal domains, respectively, are primarily responsible for the differences in transcriptional activation and plasmid maintenance, respectively. The results showed that changes within EBNA1 can differentially alter its transcriptional and replicational activities.

Animals↗
PubMed1996

Analysis of VNTR loci in fish genomes using synthetic oligodeoxyribonucleotide probes.

A set of synthetic oligodeoxyribonucleotide (oligo) probes, OAT18, OMS1 and OAT24 carrying the (TGG)6, (GGAT)4 and (GACA)6 repeat motifs, respectively, was used to analyze the variable number tandem repeat (VNTR) loci in the genomes of Oncorhyncus mykiss (rainbow trout; family Salmonidae), Oreochromis mossambicus and Oreochromis niloticus (both tilapia belonging to family Cichlidae). Of all the oligos and enzymes (AluI, MboI, HaeIII and HinfI) used, the OAT18/HaeIII combination was found to be most informative for detecting DNA fingerprinting in rainbow trout, while the OMS1/MboI combination gave the most informative pattern for the Or. niloticus genome. In the rainbow trout genome, all three repeat loci were hypervariable, revealing varying degrees of polymorphism as compared to tilapia genomes. Startlingly, the OAT24 probe did not cross-hybridize with Or. mossambicus and lamprey salmon (Lampertra japonica) although GACA repeats have been reported to be evolutionarily conserved in all eukaryotes studied thus far. Cluster analysis with respect to GGAT repeat loci revealed that Or. niloticus diverged from Or. mossambicus before the separation of On. mykiss, suggesting the relatively recent evolution of these loci in rainbow trout, compared to the tilapia genomes. These highly informative probes will find application in various genetic studies of fishes.

Animals↗
PubMed1996

A protein targeting signal that functions in polarized epithelial cells in vivo.

Eukaryotic membrane-associated polypeptides often contain a glycosylphosphatidylinositol (GPI) anchor that signals the attachment of GPI lipids to these proteins. The GPI anchor can function as a basolateral or apical targeting signal in mammalian cells cultured in vitro, although the function of the GPI anchor in vivo remains to be elucidated. In this study we have evaluated the effect of fusing a GPI anchor sequence to a prokaryotic reporter protein on the cellular location of the polypeptide in polarized epithelial cells of transgenic mice. The bacterial enzyme, when fused to a eukaryotic signal peptide, was secreted through the basolateral membrane of small-intestinal enterocytes; however, when the enzyme was lined to the GPI anchor sequence the polypeptide was redirected to the apical surface of the epithelial cells. These data provide the first direct evidence that the GPI anchor functions as an apical membrane protein sorting signal in polarized epithelial cells in vivo.

Animals↗
PubMed1996

Expression of multiple c-kit receptor messenger ribonucleic acid transcripts during postnatal development of the rat testis.

The c-kit protooncogene is a transmembrane tyrosine kinase receptor expressed during gametogenesis. Using the polymerase chain reaction (PCR), we have identified the c-kit receptor mRNA transcripts in the rat testis and studied their expression during postnatal development of the testis. Five different transcripts were identified using sets of primers encoding within the extracellular domain. Two transcripts were obtained from primer sets encoding regions within the cytoplasmic domain and the primer set encoding the entire length of the c-kit receptor. We have compared the levels of expression of these transcripts on different days during postnatal development. The level of expression of a particular transcript varied depending upon the developmental stage of the testis. In summary, our results suggest that multiple forms of mRNAs exist for the c-kit receptor in the rat testis, and they are regulated differentially during postnatal development.

Aging↗
PubMed1996

PTP1D is a positive regulator of the prolactin signal leading to beta-casein promoter activation.

Stimulation of the prolactin receptor (PRLR), a member of the cytokine/growth hormone receptor family, results in activation of the associated Jak2 tyrosine kinase and downstream signaling pathways. We report that PTP1D, a cytoplasmic protein tyrosine phosphatase containing two Src homology 2 (SH2) domains, physically associates with the PRLR-Jak2 complex and is tyrosine-phosphorylated upon stimulation with prolactin. The formation of the trimeric PRLR-Jak2-PTP1D complex is critical for transmission of a lactogenic signal, while PTP1D phosphorylation is necessary, but not sufficient. The dominant negative inhibitory effect of a phosphatase-deficient mutant on expression of a beta-casein promoter-controlled reporter gene is evidence for an essential role of fully functional PTP1D in the regulation of milk protein gene transcription.

Base Sequence↗
PubMed1996

Immunogenicity of biliary epithelium: investigation of antigen presentation to CD4+ T cells.

The intrahepatic biliary epithelium is susceptible to extensive T-cell-mediated damage during primary biliary cirrhosis, primary sclerosing cholangitis, and hepatic allograft rejection. During these processes, human intrahepatic biliary epithelial cells (HIBEC) become activated and express high levels of the lymphocyte adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and lymphocyte-associated antigen (LFA)-3, and of class II MHC antigens. It follows that activated HIBEC may also play a direct role in the activation of antigen-specific CD4+ T lymphocytes. The capacity of class II MHC antigen-expressing HIBEC to present antigen and induce specific proliferation of CD4+ T cells was examined in this study. Lines of purified HIBEC were activated by culture with the proinflammatory cytokines interferon gamma (IFN-gamma) and tumor necrosis factor a and were mixed in coculture with allogeneic CD4+ T cells. The result of interaction between these cells was assessed by measurement of lymphoproliferation and IL-2 production. Class II MHC antigen-expressing HIBEC failed to induce either lymphoproliferation or IL-2 production. However, both of these parameters of T-cell activation were positive in cocultures when a costimulation signal was delivered to T cells by adding bivalent anti-CD28 antibodies. The antigen-specific activation of these T cells was further enhanced by the addition of a cross-linking secondary antibody that caused CD28 receptor aggregation. The failure of cytokine-stimulated HIBEC to induce T-cell activation is consistent with the observation that HIBEC do not express the costimulatory CD28 ligands B7-1 or B7-2 at either mRNA or protein levels. It may be concluded that HIBEC are unlikely to play a direct role in activation of antigen-specific CD4+ T lymphocytes within the inflamed liver.

Antibodies, Monoclonal↗