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Biomedical subjects

A Gallagher

Publications and source records attributed to A Gallagher.

At least 109 records · Page 6Linked to original sources
PubMed1989

Suppress of the increase in free cytosolic calcium during the inhibition of T-cell activation by an autoantibody present in the serum of leprosy patients.

A serum factor, believed to be an IgG autoantibody, in certain patients with lepromatous leprosy inhibits the proliferation of mitogen-stimulated lymphocytes. To investigate which stage of the cell cycle was inhibited, we examined the effect of these sera on the kinetics of lymphocyte activation induced by several mitogenic agents: phytohaemagglutinin (PHA), the calcium ionophore A23187, the phorbol ester phorbol myristate acetate (PMA) and purified protein derivative of BCG (PPD). Seven out of 54 sera tested were found to inhibit PHA-stimulated proliferation. Inhibitory sera and to a lesser extent serum IgG from leprosy patients were capable of suppressing the increase in free cytosolic calcium normally observed immediately after PHA stimulation. Subsequent stages of the cell cycle, increase in cell size, the expression of the IL-2 receptor and increase in DNA were also suppressed. The inhibitory sera was not toxic and, if addition of the sera was delayed, would not inhibit lymphocytes that had already entered the cell cycle. Using mitogenic agents which act intracellularly, the normal early increase in cell size with A23187- and PMA-stimulated lymphocytes was not affected by inhibitory leprosy sera or serum IgG, but all subsequent steps in the cell cycle were suppressed; although the inhibition of proliferation in PMA-stimulated cultures was incomplete. The mechanism of action of the inhibitory sera and derived IgG, although acting through a cell surface antigen, appears to interfere with a fundamental process in activation since the effect was seen with all of the diverse stimuli examined in this study.

Autoantibodies↗
PubMed1989

Care--old style.

Explore the source record for details and available documents.

Child↗
PubMed1988

Comparison of the chemotactic behaviour of Rhizobium leguminosarum with and without the nodulation plasmid.

The chemotactic behaviour of a strain of Rhizobium leguminosarum biovar viciae was investigated. The flavanoids apigenin and naringenin, inducers of transcription of the nodulation (nod) genes, were both potent attractants but hesperitin, another flavone nod gene inducer, was not. The response of strains containing the Sym plasmid pRL1Jl to apigenin and naringenin was significantly greater than the response of a strain cured of the plasmid, although both strains gave a positive response. Addition of the flavanol kaempferol, an antagonist of nod gene induction, had no detectable effect on the chemotactic response to naringenin or apigenin, but was itself found to be an attractant. The attractant response to a variety of amino acids and sugars was not affected by the presence of the Sym plasmid. Homoserine, the most abundant nitrogenous compound in legume exudates, was also found to be an attractant. However, although the Sym plasmid is required for the biovar to metabolize homoserine as a carbon source, it was not required for the chemotactic response. A group of membrane proteins showed increased methylation in response to stimulation with serine. There was no measurable change in methylation after stimulation with apigenin.

Bacterial Proteins↗
PubMed1988

Changes in activation markers and cell membrane receptors on human peripheral blood T lymphocytes during cell cycle progression after PHA stimulation.

Phytohaemagglutinin (PHA)-stimulated peripheral blood lymphocytes were examined sequentially for changes in volume, the appearance of cell membrane receptors and nucleic acid synthesis. The kinetics of appearance of activation antigens were compared with the progress of the cell through the separate events of volume growth and nucleic acid syntheses, to determine points at which regulation of receptors may control further progress through the cell cycle. In all samples tested there was a consistent pattern of response in the proportion of cells progressing through the cell cycle. Most of the T cells increased in size (mean 82% at 24 hr), fewer cells entered the Gla/Glb phase with the onset of RNA synthesis (mean 68% at 48 hr) and even fewer entered DNA synthesis (mean 42% at 72 hr). The time-course of appearance and the number of cells expressing IL-2 receptors were almost identical with that of cells responding by RNA synthesis. A similar correlation was observed between expression of the transferrin receptor and DNA synthesis. Addition of anti-Tac antibody temporarily suppressed the onset of RNA synthesis and antibodies to the transferrin receptor suppressed DNA synthesis. These linkages are further evidence that IL-2 and transferrin are the specific signals for cellular RNA and DNA synthesis. With optimal concentrations of PHA, addition of IL-2 did not increase the proportion of cells bearing activation antigens or undergoing nucleic acid synthesis. Suboptimal concentrations of PHA produced a small reduction in the number of cells expressing the IL-2 receptor, but a much greater reduction in the rate of entry into RNA synthesis. There was a consistent increase in all activation parameters tested with the addition of IL-2, but the proportion of cells expressing the transferrin receptor and entering DNA synthesis was consistently lower than that of cells that expressed the IL-2 receptor or entered RNA synthesis. This suggests that regulation of the IL-2 receptor is not responsible for the reduction in the number of cells that proceed to proliferation. The CD2 antigen (T11(1] showed increasing expression in a step-wise fashion after activation, the increases coinciding with the onset of RNA and DNA syntheses.

Cell Cycle↗
PubMed1987

Dietary patterns and metabolic control in diabetic diets: a prospective study of 51 outpatient men on unmeasured and exchange diets.

In a prospective, single blind study, 51 adult diabetic, male outpatients at or below ideal body weight (IBW), all but four of whom were insulin-treated, were randomly assigned to a calorically defined exchange diet (EXCH) or an unmeasured diet avoiding refined sugars (UNMEAS). Fasting chemistries, weights and 48-hr dietary recalls were obtained every 3 months for 3 years. There was no difference between groups in mean body weight, mean caloric intake, percentages of carbohydrate or fat intake, day to day consistency of caloric intake, or fasting chemistries. The patients whose actual weight tended to be less than IBW consumed more calories than their theoretical calculated needs (p = 0.002) without effect on glycemic control or stability of weight. Patients with low carbohydrate intake (less than 30%) had significantly higher triglyceride levels (p = 0.015). Otherwise, variations in dietary patterns were not reflected in fasting clinical chemistries. Individual fasting serum glucose levels were not related to consistency of carbohydrate intake, caloric distribution throughout the day or composition of diets. These results suggest that actual dietary patterns of subjects following exchange diabetic diets with precise caloric prescriptions are similar to those resulting from unmeasured diets with restriction of simple sugars. Other than correlation between carbohydrate intake and triglycerides, there was no detectable effect of variations in dietary patterns upon conventional chemical metabolic levels.

Adult↗
PubMed1979

The yeast mitochondrial ATPase complex. Subunit composition and evidence for a latent protease contaminant.

1. The subunit compositions of the F1 (oligomycin-insensitive) and F1--F0 (oligomycin-sensitive) mitochondrial ATPase complexes from Saccharomyces cerevisiae have been examined by the highly resolving technique of sodium dodecyl sulphate-polyacrylamide slab gel electrophoresis using a discontinuous buffer system. When isolated in the presence of protease inhibitors, F1 and F1--F0 contained five and twelve bands, respectively; this contrasts with the four- and ten-band patterns seen previously using the less resolving disc gel method. When isolated in the absence of protease inhibitors both F1 and F1--F0 contain spurious polypeptides produced by proteolytic modification. 2. Endogenous protein turnover in S. cerevisiae was impaired in the presence of protease inhibitors. F1--F0 isolated from cells grown in the presence and absence of inhibitors contained an identical polypeptide composition, suggesting that the subunits are not significantly modified by endogenous proteases prior to cell harvesting. 3. Yeast F1--F0 prepared in the presence of protease inhibitors contains a latent, sodium dodecyl sulphate-activated protease contaminant. Sodium dodecyl sulphate-induced proteolysis is largely confined to the 52 000 dalton alpha subunit which degrades into polypeptides of 40 000 and 10 700 daltons. The 40 000 dalton band is apparently equivalent to the polypeptide previously designated subunit 3. 4. Both F1 and F1--F0 were isolated from Torulopsis glabrata, a yeast with considerably shorter mitochondrial DNA than that in S. cerevisiae. F1--F0 catalysed high rates of ATP--32Pi exchange when reconstituted into phospholipid vesicles, thus demonstrating the presence of a complete coupling mechanism. F1--F0 contained approximately twelve subunits and F1 five, like the S. cerevisiae complexes. It therefore appears that the shorter mitochondrial DNA length does not produce a significantly simpler ATPase subunit structure.

Adenosine Triphosphatases↗
PubMed1975

Reducing diets in rats.

Adult obese rats were restricted to equal intakes provided by four diets which varied widely in protein, fat and carbohydrate content. Loss in body weight and body fat was similar in all groups. The only significant dietary effect observed was a modest increase in the body protein content of the animals fed the high protein diets. Low carbohydrate--high fat--high protein diets, as expected, showed no advantage as reducing diets when compared to other diets on an equal calorie basis.

Animal Nutritional Physiological Phenomena↗