PubMed Health⌕ Search

Biomedical subjects

A Samad

Publications and source records attributed to A Samad.

At least 37 records · Page 2Linked to original sources
PubMed1991

The tumor suppressor p53 is bound to RNA by a stable covalent linkage.

We have previously shown that the carboxyl-terminal tryptic peptide of the tumor suppressor p53 coeluted from reverse-phase high-performance liquid chromatography (HPLC) with ribonucleotides, suggesting the possible linkage of RNA to p53. In this report, we establish that p53 is covalently linked to RNA, using biochemical criteria at the levels of both tryptic peptide and intact protein: the electrophoretic properties of a tryptic peptide containing phosphorylated Ser-389 and the HPLC chromatographic properties of p53 depend on the linked RNA, p53, purified through urea-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and HPLC, copurifies with RNA, and Ser-389 liberates ribonucleotides upon RNase or alkali treatment. Wild-type and mutant p53s from both simian virus 40 (SV40)-transformed and SV40-nontransformed cells are RNA linked, indicating that RNA linkage may be a general property of p53. The RNA is labeled in vivo with 3H-uridine and in vitro by RNA ligase, suggesting that the RNA is bound by a 5' linkage. The RNA is a long-lived, integral component of p53 rather than a transient reaction intermediate. RNA linkage occurs at an evolutionarily conserved site on p53. We propose that RNA-linked p53 is a major biologically active form of p53 and that its interaction with RNA-linked SV40 T antigen reflects a role in RNA metabolism.

Animals↗
PubMed1991

Assessment of low attendance at primary health care centre.

The study was conducted at 11 (eleven) randomly selected villages of Rupganj Upazila in order to find out the way to promote Primary Health Care. 1186 household heads and 11 physicians interviewed for the purpose. The study revealed that more than 54.14 percent of the study population were suffering from various diseases and only 4 percent of the patients attended Primary Health Care Centre/Complex. 52% of the patients were not satisfied by the service of Primary Health Care Centre/Complex. Want of medicine, lack of good physicians and doctors, carelessness about the patients constituted the principal causes of unsatisfactory treatment. The comparative distribution of opinion of household heads and physicians about non-attendance to Primary Health Care Centres by patients is statistically insignificant (P less than 0.05) which implies that the opinions are more or less the same. Both household heads and physicians opined that supply of sufficient medicine, equipment, improvement of health education and more budget allocations are essential to make the Primary Health Care service effective.

Bangladesh↗
PubMed1991

Hypercalcemia in a patient with tuberculous mediastinal lymphadenopathy.

We describe the case of a 48 year old Indian female with hypercalcemia due to tuberculosis. She presented with symptoms of hypercalcemia and chest radiographs showed bilateral hilar lymphadenopathy with normal lung fields. The diagnosis of tuberculosis was made histologically from biopsy of the enlarged hilar nodes. Her hypercalcemia resolved following one month of anti-tuberculous treatment. The prevalence of hypercalcemia in tuberculosis has been reported to be high in western series. There is, however, a paucity of local data on the subject. The presence of 1-alpha-hydroxylase-like activity in pulmonary alveolar macrophages with resulting increased formation of active vitamin D metabolites is the postulated mechanism of tuberculosis associated hypercalcemia.

Female↗
PubMed1989

The acquisition of lipids by African trypanosomes.

Bloodstream forms of African trypanosomes are dependent on their host for fatty acids, choline and other components of membrane lipids. The bulk of their choline requirement is met by their ability to take up lysophospholipids from the host tissue fluids. Trypanosoma brucei has ocyltransferose and phospholipase A(1) activities for the metabolism of exogenous lysophospholipids. The rate of uptake of lysophospholipids can be controlled by changes in the extrocellulor concentration of fatty ocyl-coenzyme A, and this control has potential for chemotherapy.

Journal Article↗
PubMed1988

Metabolism of phospholipids and lysophospholipids by Trypanosoma brucei.

African trypanosomes (Trypanosoma brucei brucei) rapidly metabolize exogenous 1-acyl-lysophospholipids by at least two routes: (1) hydrolysis by a phospholipase A1; (2) acylation by an acyl-CoA-dependent acyltransferase. In contrast to lysophospholipids, exogenous phospholipids are not rapidly metabolized by T. brucei. The acyltransferase (EC 2.3.1.23) converts exogenous 1-acyl lysophosphatidylcholine and exogenous acyl-CoA to phosphatidylcholine and CoA-SH. It is a membrane-bound enzyme and shows maximal activity within the first 2 min of exposure of trypanosomes to the exogenous substrates. The acyltransferase specificity for lysophospholipids is lysophosphatidylcholine greater than lysophosphatidylinositol greater than lysophosphatidylethanolamine greater than lysophosphatidate. Phosphatidylcholine enhances the enzyme activity towards lysophosphatidylethanolamine and lysophosphatidic acid. The preference for CoA acyl thioesters is oleoyl greater than palmitoyl greater than myristoyl greater than stearoyl greater than arachidonoyl, and this specificity distinguishes the protozoan enzyme from those of cells of mammalian hosts, which are specific for arachidonoyl-CoA. When the acyltransferase converts exogenous lysophosphatidylethanolamine to phosphatidylethanolamine, the latter is rapidly methylated to form dimethylphosphatidylethanolamine. There is also rapid hydrolysis of exogenous oleoyl-CoA by a thioester hydrolase in living trypanosomes, to yield free oleate and CoA-SH.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1988

RNA is covalently linked to SV40 large T antigen.

RNA is shown to be covalently linked to the large tumor antigen (TAg) of simian virus 40 (SV40). Proteolytic digestion of TAg, isolated in the presence of ribonuclease inhibitors from SV40 transformed Balb/c mouse cells, generated a specific phosphopeptide of high charge heterogeneity that was strongly retained on DEAE-cellulose in the presence of 7 M urea. Hydrolysis of this peptide with RNAase released the four standard ribonucleotide monophosphates. Analysis of peptide digestion products showed that the RNA is attached to TAg through a phosphodiester linkage between the beta-hydroxyl of a serine and the 5' phosphate of an invariant cytidine residue. The methods applied to SV40 TAg can be applied to other proteins, including cellular oncogene products, to investigate the possibility of covalent protein-RNA interactions.

Antigens, Polyomavirus Transforming↗
PubMed1986

Mapping of phosphomonoester and apparent phosphodiester bonds of the oncogene product p53 from simian virus 40-transformed 3T3 cells.

The oncogene product p53, isolated from SV3T3 cells where it forms a complex with simian virus 40 large tumor antigen (T antigen) in the nucleus, has been found to be phosphorylated at at least four distinct sites on the 390 amino acid protein. Separation of tryptic phosphopeptides has permitted identification of two sites as Ser-312 and Ser-389, and permitted analysis of the types of phosphate bonds. The peptide containing Ser-312 separates electrophoretically into three charged forms; two are resistant to dephosphorylation by both alkaline phosphatase and alkaline hydrolysis, suggesting a phosphodiester. The carboxyl-terminal phosphopeptide containing Ser-389 was alkaline phosphatase-resistant and liberated four ribonucleoside monophosphates upon base or RNase hydrolysis, suggesting that Ser-389 may be covalently linked to RNA. Phosphorylation of Ser-389 decreased markedly at the nonpermissive temperature in simian virus 40 tsA58-transformed cells, indicating a dependence on native T antigen function and a possible role in transformation by T antigen. Two additional phosphorylation sites, one involving serine and one involving threonine, probably reside in the amino-terminal segment of p53 and appear to be peptide-phosphate monoesters.

Animals↗
PubMed1985

Histological spectrum of cutaneous leishmaniasis due to Leishmania tropica.

Skin biopsies from 117 cases of acute and 23 cases of lupoid leishmaniasis were studied. Of the 117 acute cases, anergic macrophage response were seen in 44, diffuse necrosis in 9 and focalized necrosis in 11 biopsies; the remaining 53 biopsies showed scanty or no parasites with a few to abundant epithelioid cells probably representing post necrotic changes before complete healing of the lesions. The 23 biopsies of lupoid leishmaniasis showed rather well organized epithelioid granulomata surrounded by lymphocytes, inconspicuous plasma cells, no amastigotes and no necrosis. Lupoid cases showed strong delayed hypersensitivity with leishmanin and low serum antibody titres. It appears that the lesions of urban cutaneous leishmaniasis spend a long time in the anergic phase. Partial destruction of parasites by activated macrophages together with gradual elevation of antibody levels prepares the appropriate antigen-antibody ratio for optimum development of necrosis at PI3 leading to effective elimination of parasites. Plasma cells appear to be important in the induction of necrosis and inhibition of epithelioid granulomata. A significant inverse relationship has been found between plasma cells and epitheloid cells. The delayed hypersensitivity observed in lupoid leishmaniasis is probably the result of a poor humoral response evidenced by inconspicuous plasma cells and low serum antibody titres.

Adolescent↗
PubMed1984

Trace elements in serum from Pakistani patients with acute and chronic ischemic heart disease and hypertension.

We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.

Adult↗
PubMedDate not supplied

Carbohydrate tolerance status in patients with myocardial infarction.

Hyperglycemia is an important independent risk factor in the development of coronary artery disease. Sixty one patients suffering from chronic and acute myocardial infarction out of which 12 patients were diabetic and 10 normal control subjects were investigated. The patients without diabetes and control subjects were subjected to oral and intravenous glucose tolerance tests. It was observed that the post load glucose level of most of the patients and fasting insulin level of patients without diabetes were higher as compared with control subjects. From the intravenous glucose tolerance test, half life of glucose and glucose assimilation coefficient were determined. Half life of glucose was increased significantly and glucose assimilation coefficient was decreased in the patients with myocardial infarction as compared with those of control subjects. The observations confirm that carbohydrate intolerance in myocardial infarction is not due to suppression of insulin secretion but due to peripheral utilization.

Blood Glucose↗