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Biomedical subjects

S Barry

Publications and source records attributed to S Barry.

At least 55 records · Page 3Linked to original sources
PubMed1990

Changes in basal and stimulated growth hormone secretion in the aging rhesus monkey: a comparison of chair restraint and tether and vest sampling.

We studied basal serum GH and GH responses to iv clonidine and insulin-induced hypoglycemia in a group of four young (5-7 yr old) and four older (10-14 yr old) adult male rhesus monkeys under two restraint conditions, chair adaptation and a tether and vest system, to determine what changes in GH secretion occur with aging. The serum GH response to iv administration of GH-releasing hormone (GHRH) was also studied in the groups under tether and vest restraint. Serum samples were collected every 15 min and assayed for GH using a human GH RIA and for cortisol using an enzyme-linked immunosorbant assay. GH and cortisol concentrations in the young and older groups were analyzed with analysis of variance (ANOVA). In the chaired studies the older animals had a lower mean 6-h basal GH concentration than did the younger animals (2.7 +/- 0.8 vs. 3.5 +/- 0.5 micrograms/L; P = 0.0002). Prestimulation GH was lower before clonidine and insulin in the older chaired group (1.1 +/- 0.5 and 2.3 +/- 0.6 micrograms/L, respectively) compared to the younger group (3.6 +/- 0.8 and 3.8 +/- 0.7 micrograms/L, respectively; P less than 0.001). Poststimulation GH was lower after clonidine and insulin in the older chaired group (3.2 +/- 2.4 and 7.1 +/- 2.8 micrograms/L, respectively) compared to the younger chaired group (6.3 +/- 2.2 and 10.3 +/- 3.0 micrograms/L, respectively; P less than 0.05), but the differences in GH increments were not statistically significant. In the tether and vest studies the older animals had a lower mean 6-h basal GH concentration than did the younger animals (1.7 +/- 0.4 vs. 3.5 +/- 1.2 micrograms/L; P less than 0.0001). Prestimulation GH concentrations were also lower in the older tethered animals before clonidine (2.1 +/- 0.3 micrograms/L) and GHRH (1.4 +/- 0.2 micrograms/L) compared to levels in the younger animals (3.1 +/- 0.9 and 3.2 +/- 0.7 micrograms/L; P = 0.0023 and P = 0.0001, respectively). The younger tethered animals had greater poststimulation responses to clonidine (8.7 +/- 3.0 micrograms/L), insulin (8.8 +/- 3.6 micrograms/L), and GHRH (6.0 +/- 2.4 micrograms/L) than the older animals (3.8 +/- 0.9, 3.9 +/- 2.5, and 2.9 +/- 0.7 micrograms/L; P less than 0.0001, P = 0.0025, and P less than 0.03, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1990

Serotonin supersensitivity: the pathophysiologic basis of non-ulcer dyspepsia? A preliminary report of buspirone/prolactin responses.

Buspirone stimulates central 5-hydroxytryptamine (5HT) receptors and brings about the release of prolactin, and there is evidence to suggest that the extent of prolactin release after a challenge with buspirone is an indicator of the sensitivity of central 5HT receptors. Seventeen patients with a diagnosis of non-ulcer dyspepsia, eight normal healthy volunteers, and six patients with peptic ulcer disease were each given a challenge test of 60 mg buspirone orally, and prolactin release over a 3-h period was monitored. The mean prolactin response was significantly greater in patients with non-ulcer dyspepsia than in healthy controls and peptic ulcer disease patients. The results suggest that central 5HT receptors may be supersensitive in non-ulcer dyspepsia.

Buspirone↗
PubMed1989

A comparison of electroconvulsive therapy with a combined lithium and tricyclic combination among depressed tricyclic nonresponders.

Thirty severely depressed patients who were resistant to tricyclic antidepressant therapy were randomly allocated to treatment either with electroconvulsive therapy (ECT) or addition of lithium (Li) to the tricyclic. Twenty-one of the 30 patients significantly improved at the end of 3 weeks of treatment. There were no differences in improvement rates between the two groups. However, the patients treated with a Li/tricyclic combination improved more rapidly, showing significant alterations in mental state by day 7. It is suggested that in otherwise physically healthy patients who are tricyclic nonresponders, the addition of Li may be a more rapid treatment than the use of ECT.

Adult↗
PubMed1985

Clinical and subclinical thiamine deficiency in clinical practice.

Six patients with gross thiamine deficiency found during normal psychiatric practice in England are described. Two surveys of newly admitted psychiatric patients are recounted. A major degree of biochemical deficiency, with or without minimal clinical manifestations, was found. Only three (1%) of 326 patients surveyed had gross clinical deficiency. It is thought that severe thiamine deficiency, though rare in the Western countries, has not been eradicated. Deficiency may cause psychiatric conditions like Wernicke's encephalopathy or may be a secondary feature in mental illness due to anorexia, in reduced food intake, and in poor nutrition. The importance of being aware of the possibility for correct diagnosis is emphasised.

Aged↗
PubMed1982

Influence of osmolality and ionic environment on the secretion of prolactin by human decidua in vitro.

The effects of extracellular osmolality and ions on the secretion of prolactin were examined in human decidual explants incubated for 4 h in modified Krebs-Ringer buffer. Explants incubated in media made hypersomotic (280-336 mosM/kg) with sodium, lithium or mannitol or in media made hypo-osmotic (280-224 mosM/kg) by decreasing the sodium concentration secreted the same amount of prolactin as explants incubated in control medium (280 mosM/kg). Explants incubated in calcium-deficient medium secreted 64 +/- 8% (P less than or equal to 0.001) less prolactin than controls (1.65 mmol Ca2+/1). Secretion was restored to control values by the addition of calcium (0.33 mmol/l) or barium (0.5, 1.0 or 2.0 mmol/l) to the medium. Prolactin secretion was unaffected by higher than control extracellular calcium concentrations, calcium ionophore A23187 (10-6, 10-9 mol/l) or lanthanum (0.5, 1.0 or 2.0 mmol/1). Changes in extracellular magnesium (0-20 mmol/l), potassium (0-55 mmol/l) or bicarbonate (0-32 mmol/l) had no effect on prolactin secretion. These results indicate that marked changes in extracellular osmolality and concentrations of sodium, magnesium and bicarbonate have no effects on decidual prolactin secretion. Calcium, however, is essential for the basal secretion of decidual prolactin.

Calcium↗
PubMed1981

Human placental lactogen release in vitro: paradoxical effects of calcium.

To study the effects of calcium on the release of human placental lactogen (hPL), placental explants were exposed to media containing lower or higher concentrations of calcium than normally available to the placenta. Explants exposed for 2 h to calcium-poor medium or medium containing either 2 mM EDTA or 2 mM EGTA released 160, 248, and 253% more hPL, respectively, than control explants. In contrast, explants exposed to medium containing higher than normal calcium concentrations released the same amounts of hPL as the control explants. At lower than normal extracellular calcium concentrations, the increased hPL release was inversely proportional to the calcium concentration. The increased release in calcium-poor medium was inhibited by subsequent exposure of the explants to medium containing calcium and was prevented by either barium or magnesium. Changes in barium or magnesium concentrations, however, had no effects on hPL release in the presence of normal extracellular calcium concentrations. Methoxyverapamil (D 600), an inhibitor of calcium flux, stimulated hPL release. Because low extracellular calcium and methoxyverapamil both inhibit calcium influx, these experiments suggest that calcium influx inhibits hPL release. The role of calcium in the regulation of hPL release therefore appears to be different from that reported in other release systems.

Barium↗
PubMed1981

Inhibition of the synthesis and secretion of decidual prolactin by arachidonic acid.

Human decidual explants exposed for 4 h to 150 microM arachidonic acid synthesized and secreted 30.4% (P less than 0.001) and 36.4% (P less than 0.001) less 35S-PRL, respectively, than control explants. Over a 5-h period, the inhibition of PRL secretion was directly proportional to the arachidonic acid concentration at concentrations between 30 and 300 microM (r = 0.91; P less than 0.001). Phospholipase A2 at concentrations of 0.11 and 11.1 U/ml, also inhibited PRL secretion by 46.2 +/- 2.4% (P less than 0.001) and 63.9 +/- 1.4% (P less than 0.001), respectively. Likewise, the fatty acid precursors of arachidonic acid, i.e. linoleic, gamma-linolenic, and dihomo-gamma-linolenic acids, inhibited PRL secretion, but palmitic, oleic, and 11,14,17-icosatrienoic acids and the detergents deoxycholic acid and Triton X-100 had no effects, even at concentrations as high as 300 microM. In contrast, prostaglandins E1, E2, and F2 alpha (3 X 10(-5)-10(12) M each) had no effects on PRL secretion, and the prostaglandin synthetase (cyclooxygenase) inhibitors indomethacin (5 and 25 micrograms/ml) and flufenamic acid (5 micrograms/ml) had no effects on either basal PRL secretion or the inhibitory action of arachidonic acid. These results suggest that arachidonic acid may be involved in the regulation of the synthesis and secretion of decidual PRL. The effect of arachidonic acid, however, does not appear to be mediated by a cyclooxygenase product of arachidonic metabolism.

Arachidonic Acid↗
PubMed1981

Stimulation by ornithine of ovine placental lactogen secretion.

Arginine is a potent stimulus to the secretion of placental lactogen (PL) as well as GH and prolactin in sheep. To determine whether other amino acids of the urea cycle also affect PL secretion, ornithine (25 g) and citrulline (20 g) were infused intravenously into four pregnant ewes over a period of 0.5 h. In eight experiments, ornithine stimulated PL secretion by 124 +/- 25 (S.E.M.) % with the initial increase occurring by 1 h after the start of each infusion. Plasma GH concentrations increased from 3.4 +/- 1.1 to 24.5 +/- 5.9 ng/ml and plasma prolactin concentrations increased from 58.8 +/- 12.8 to 310.7 +/- 88.4 ng/ml. Citrulline, on the other hand, had no consistent effect on PL secretion. Plasma GH concentrations following the infusion of citrulline, however, increased by 15-20 ng/ml in two of four experiments and plasma prolactin concentrations decreased by 73.2 +/- 3.2% in all four experiments. The results indicate that ornithine is also a potent stimulus to the secretion of PL, GH and prolactin and suggest that arginine-induced PL secretion may result from the conversion of arginine to ornithine.

Animals↗
PubMed1979

N6-[N-(6-Aminohexyl)carbamoylmethyl]-coenzyme A. Synthesis and application in affinity chromatography and as an immobilized active coenzyme.

The synthesis of a new coenzyme A analogue, N6-[N-(6-aminohexyl)carbamoylmethyl]-CoA, suitable for immobilisation through its terminal amino group to support matrices, is described. The synthetic route starts with bis(CoA) and involves the following steps: alkylation with iodoacetic acid and rearrangement yielding bis(N6-carboxymethyl-CoA), elongation of the carboxymethyl terminal with 1,6-diaminohexane using carbodiimide to yield bis(N6-[N-(6-aminohexyl)-carbamoylmethyl]-CoA) and finally the splitting of this bis[CoA analogue) through reduction with dithiothreitol to give the final product in approximately 10% overall yield. This CoA analogue showed 'coenzymic activity' with the enzymes acetyl-CoA synthetase, phosphotransacetylase and succinic thiokinase. Covalent binding of the CoA analogue to Sepharose 4B was normally carried out using its S-(5-thio-2-nitrobenzoic acid) derivative as this allows a convenient way for determining the amount of ligand coupled, based on the amount of 5-thio-2-nitrobenzoic acid liberated from the gel after reduction with dithiothreitol. After covalent binding of the CoA analogue to water-soluble activated dextran 70, the analogue was recycled while present in an ultrafiltration cell using the enzymes phosphotransacetylase and citrate synthase. The reaction was followed by measuring the citrate formed on addition of acetylphosphate and oxaloacetate. In affinity chromatographic studies it was shown that the CoA-Sepharose preparation could bind the CoA-dependent enzymes citrate synthase and succinic thiokinase and these could be biospecifically eluted using soluble CoA.

Animals↗
PubMed1979

Failure of bromocriptine, dopamine, and thyrotropin-releasing hormone to affect prolactin secretion by human decidual tissue in vitro.

To determine whether the secretion of PRL by human decidual tissue in vitro is influenced by factors which inhibit or stimulate pituitary PRL secretion, explants of decidual tissue were incubated in media containing bromocriptine, dopamine, or TRH at concentrations known to affect pituitary PRL secretion in vitro. The quantities of PRL secreted by the explants exposed to these factors were compared with amounts secreted by explants incubated in control medium. Bromocriptine in concentrations ranging from 1.5 x 10(-10) to 1.5 x 10(-7) M did not inhibit PRL secretion over a 3-day period and dopamine in concentrations ranging from 5 x 10(-5)-10(-9) M did not inhibit PRL secretion over a 4-h period. TRH in concentrations ranging from 10(-9)-10(-3) M did not stimulate PRL secretion. These results suggest that the mechanism of PRL secretion by decidual tissue in vitro is different, at least in part, from the mechanism of pituitary PRL secretion.

Bromocriptine↗