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Biomedical subjects

H Ali

Publications and source records attributed to H Ali.

At least 109 records · Page 6Linked to original sources
PubMed1987

Identification of variants of the basophilic leukemia (RBL-2H3) cells that have defective phosphoinositide responses to antigen and stimulants of guanosine 5'-triphosphate-regulatory proteins.

Antigen immunoglobulin E-mediated secretion of histamine from RBL-2H3 cells is associated with substantial hydrolysis of membrane inositol phospholipids and a rise in the concentration of cytosol Ca2+ (calcium signal). Such responses differed among cloned variant lines of the RBL-2H3 cell line from undetectable (1A3 bromodeoxyuridine-resistant (BUDRR), 2B1 BUDRR, and 1B3 BUDRR lines) to about 80% of those in the parent RBL-2H3 cells. In all but one line (1B3 thioguanine-resistant (TgR)), the intensities of the phosphoinositide response and of the calcium signal were correlated with the secretory response. The 1B3 TgR line had no detectable calcium signal (as measured by quin 2 fluorescence or uptake of 45Ca2+) but paradoxically showed modest rates of hydrolysis of inositol phospholipids and of secretion. The responses of the 1B3 TgR line were, however, dependent on the presence of external Ca2+ ions. The induction of secretion with antigen, therefore, was invariably associated with the hydrolysis of inositol phospholipids, but it was not necessarily associated with a change in concentration of cytosol Ca2+. All antigen unresponsive clones could secrete when synergistic signals were induced by exposure to the Ca2+ -ionophore, A23187 and the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate. These lines, otherwise, had immunoglobulin E receptors and had no obvious defect in their capacity to synthesize the inositol phospholipids or in their phenotypic expression of phospholipase C as measured in cell extracts. One finding of possible relevance to the role of guanosine 5'-triphosphate-regulatory proteins in the activation of phospholipase C was the inability of one antigen-nonresponsive line to respond to NaF (in intact cells) or to guanosine 5'-(3-O-thio)triphosphate (in electrically permeabilized cells).

Animals↗
PubMed1987

Regioselective A-ring iodination of estradiol diacetates.

Treatment of estrone or estradiol acetate with thallium trifluoroacetate in TFA and subsequent reaction with KI gave the 2-iodoestrogens as the major product. In the case of estradiol diacetate, treatment of the thallation product with [125I]NaI, using the same reaction conditions, gave exclusively the 2-iodo isomer. Thus, regioselectivity combined with rapidity, renders this procedure particularly suitable for A-ring radioiodination of estradiol with short-lived isotopes.

Estradiol↗
PubMed1986

Some studies on the release of histamine from mast cells treated with d-tubocurarine.

d-Tubocurarine (dTc) released histamine in non-cytotoxic fashion from peritoneal mast cells of the rat, mouse and hamster. The response was similar to that evoked by other cationic liberators such as compound 48/80 and polylysine in that it was extremely rapid and enhanced by calcium-deprivation at suboptimal concentrations of secretagogue. Tissue mast cells obtained by enzymic dissociation of the heart, lung and mesentery of the rat and guinea pig were unreactive or hyporesponsive to the effect of dTc. The compound liberated only very small amounts of histamine from isolated preparations of perfused guinea pig heart but significantly increased the rate and contractility of the heart. These results are discussed in terms of the general functional heterogeneity of mast cells from different locations.

Animals↗
PubMed1986

Comparison of the histamine-releasing action of substance P on mast cells and basophils from different species and tissues.

The action of the neuropeptide substance P as a histamine-releasing agent has been compared in histamine-containing cells from a variety of different tissues and species. Peritoneal mast cells from rat, mouse and hamster but not human cells gave a concentration-dependent release of histamine in response to substance P. Release was greater in the absence than in the presence of calcium in the extracellular medium. Mast cells from rat mesentery, lung and heart released histamine in response to substance P, but heart mast cells responded only weakly. All guinea-pig mast cells and histamine-containing cells from human tissues did not give any substantial substance-P-induced release of histamine. The data provides further evidence for the functional heterogeneity of histamine-containing cells.

Animals↗
PubMed1985

Isolation and properties of cardiac and other mast cells from the rat and guinea-pig.

A method is described for the enzymic dispersion into their component cells of cardiac tissues from the rat and guinea-pig. The resulting suspensions contain ca. 1% free mast cells and exhibit a low spontaneous release of histamine. The reactivity of these cells towards a number of defined chemical histamine liberators is compared with that of other connective tissue mast cells from the same animals. The results obtained are discussed in terms of the general functional heterogeneity of mast cells from different locations.

Animals↗
PubMed1985

Synthesis, tissue distribution and tumor uptake of 99mTc- and 67Ga-tetrasulfophthalocyanine.

Complexes of tetrasulfophthalocyanine with 99mTc, 69Ga and 67Ga were prepared by the condensation of sulfophthalic acid with the appropriate metal-species. The Ga-complex was also obtained by exchange of the central hydrogens of the empty tetrasulfophthalocyanine. The labeled complexes were purified by thin layer chromatography and characterized by their chromatographic properties. Their biodistribution in rabbits and tumor-bearing rats revealed that most of the radioactivity accumulated in the kidneys, liver, ovaries, adrenals and spleen. Comparison of these distribution pattern with those of [99mTc]pertechnetate and 67Ga-citrate confirmed the in vivo stability of the labeled complexes. The 67Ga-complex reached better tumor-to-blood and tumor-to-muscle ratios than 67Ga-citrate.

Adenocarcinoma↗
PubMed1985

Studies on histamine secretion from enzymically dispersed cutaneous mast cells of the rat.

A method has been developed for the enzymic dissociation of rat skin into its component cells. The resulting suspensions contained 3-5% mast cells. The latter were intact as judged by light microscopy and exhibited a low spontaneous release of histamine. Cells obtained from actively sensitized animals released histamine on challenge with specific antigen. The process was rapid, being essentially complete within 1 min, and was both calcium-and temperature-dependent. The cells also responded to antirat IgE and to calcium ionophores but showed a selective, time-dependent reactivity toward defined chemical histamine liberators. On the basis of these results the properties of the cutaneous mast cell are compared with those previously reported for mastocytes from other sources and discussed in terms of the general heterogeneity of this cell population.

Animals↗
PubMed1985

The ability of thapsigargin and thapsigargicin to activate cells involved in the inflammatory response.

The ability of thapsigargin and thapsigargicin to activate mast cells and leukocytes has been investigated. The thapsigargin-induced histamine release from rat peritoneal mast cells was found to be dependent on the concentration of thapsigargin, the purity of the mast cell preparations, and the number of mast cells in suspension. Thapsigargin induced histamine release from human basophil leukocytes. Thapsigargin induced beta-glucuronidase and lysozyme release from human neutrophil leukocytes. Thapsigargin caused a release of histamine from mesentery, lung, and heart mast cells of the rat, but only to a minor extent from the corresponding guinea-pig cells. Thapsigargicin induced histamine release from mesentery, lung, and heart mast cells of the rat at concentrations from 0.1 microM but provoked only a release from the corresponding guinea-pig cells in the concentration-range 0.16 to 1.6 microM. Thapsigargin increased the cytoplasmic free calcium level in intact human blood platelets at concentrations from 3.0 nM.

Adult↗