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Biomedical subjects

J Barnes

Publications and source records attributed to J Barnes.

At least 145 records · Page 8Linked to original sources
PubMed1986

Characterization of 1,25-dihydroxyvitamin D3-dependent calcium uptake in isolated chick duodenal cells.

The in vivo and in vitro effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on calcium uptake by isolated chick duodenal cells were studied. In vivo, 1,25-(OH)2D3 given orally to vitamin D-deficient chicks increased the initial rate of calcium uptake by cells prepared 1 hr after administration of the hormone. The rate was stimulated approximately 100%, 17 to 24 hr after repletion. In vitro, pre-incubation of 1,25-(OH)2D3 with cells from D-deficient chicks increased the cellular rate of calcium uptake in a concentration-dependent relationship. Enhancement was found with 10(-15) M, was maximal at 10(-13) M, and was diminished at higher (10(-11) M) concentrations. Stimulation was observed after a pre-incubation period as brief as 1 hr. The potency order for vitamin D3 analogs was 1,25-(OH)2D3 = 1-(OH)D3 greater than 25-(OH)D3 greater than 1,24,25-(OH)3D3 greater than 24,25-(OH)2D3 greater than D3. The maximal enhancement in calcium uptake induced by the analogs was the same, only the concentration at which the cell responded was different. The effectiveness of 1,25-(OH)2D3 was five orders of magnitude greater than D3. Kinetically, 1,25-(OH)2D3 increased the Vmax of calcium uptake; the affinity for calcium (Km = 0.54 mM) was unchanged. The enhanced uptake found after the cells were pre-incubated for 2 hr with the hormone was completely blocked by inhibitors of protein synthesis. 1,25-(OH)2D3, in vitro, also increased calcium uptake in cells isolated from D-replete chicks. The maximal rates of uptake were the same in cells from D-deficient and D-replete animals. The hormone had no effect on calcium efflux from cells. Calcium uptake in microvillar brush-border membrane vesicles was increased by 1,25-(OH)2D3. These findings suggest that the in vitro cell system described in this paper represents an appropriate model to examine the temporal relationships between 1,25-(OH)2D3 induction of calcium transport and specific biochemical correlates.

Animals↗
PubMed1986

Effects of drug and alcohol abuse upon pituitary-testicular function in adolescent males.

To assess the effects of drug and alcohol abuse (DAA) on the physical changes and hormones of puberty in adolescents, 26 males (13 5/12-22 years) enrolled in a drug rehabilitation program were examined. In 22 subjects four timed blood samples were obtained sequentially at 15 minute intervals for measurement of serum concentrations of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and dehydroepiandrosterone sulfate (DHAS). The mean duration of DAA was 3.7 years, with marijuana and alcohol being the most frequently abused substances. The study subjects were compared to a matched control group of non-substance-abusing teenagers. All heights and weights of the DAA subjects fell within two standard deviations of the mean on the Tanner Growth Charts and no statically significant differences in the Tanner stages of sexual maturation were found between the DAA and control groups. The mean (+/- SD) testosterone level of the DAA group (221 +/- 109 ng/dl) was less than half that of the control group (477 +/- 193 ng/dl, p less than 0.001). Mean LH concentration in the DAA group (3.9 +/- 3.0 mIU/ml) was significantly less than that of the control group (10 +/- 4.9 mIU/ml, p less than 0.01). In both the DAA and control populations there was a significant (p less than 0.01) correlation between serum concentrations of LH and testosterone. The mean FSH level of the DAA group (3.3 +/- 1.1 mIU/ml) was significantly less (p less than 0.02) than that of the control group (4.7 +/- 1.9 mIU/ml). To assess the effects of treatment, six boys underwent repeat blood sampling 7-12 months after drug and alcohol withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Temperature maintenance in infants undergoing anaesthesia and surgery.

A study has been conducted on infants under six months of age during induction and anaesthesia to compare the effect on heat loss when a warming blanket, a humidifier and an overhead heater were used. The combination of all three was associated with significantly less heat loss than when the blanket was used alone. The particular benefit of the overhead heater during prolonged preparation for neurosurgery was also demonstrated. It is recommended that overhead heaters should be used during induction of anaesthesia in infants.

Anesthesia↗
PubMed1984

Biofeedback as an adjunct to psychotherapy in the treatment of vaginismus.

This exploratory study examines the use of biofeedback as an adjunct to psychotherapy in the treatment of vaginismus. A set of six Sims-type graded EMG probes was constructed to provide biofeedback from the vaginal sphincter and was tested on a pilot sample of nulliparous women prior to this study. Five sequential cases of vaginismus from a clinic waiting list participated in the program. All five couples completed the program and all reported successful intercourse at its conclusion. The number of sessions devoted to biofeedback probe insertion was almost halved in comparison to previous experience with Sims dilators. Overall treatment duration was not shortened. At follow-up 6 months later, two couples reported pregnancy, one couple was having regular intercourse, and two couples had ceased intercourse. The authors conclude that biofeedback is an effective aid to learning muscle control, is acceptable to patients, and may increase the success rate by minimizing dropouts. The importance of follow-up is stressed.

Adult↗
PubMed1984

Responses of chick renal cell to parathyroid hormone: effect of vitamin D.

The in vitro incubation of chick renal cells with parathyroid hormone (PTH) resulted in the inhibition of Na+-dependent phosphate uptake when the cells were isolated from 1,25-dihydroxycholecalciferol 1,25-dihydroxycholecalciferol [1,25-(OH)2D3]-repleted chicks but not when the cells came from vitamin D-deficient animals. Na+-independent phosphate and Na+-dependent alpha-methylglucoside uptakes were not affected by PTH and the vitamin D status of the bird. The activation of chick renal cell adenylate cyclase by PTH was significantly blunted when the enzyme was from vitamin D-deficient animals relative to the activation of the enzyme from repleted cockerels. This alteration was due to a change in maximum velocity of the system rather than an effect on the affinity for hormone. The response of adenylate cyclase to other hormones, e.g., prostaglandin E2, and activators, e.g., 5' -guanylyl-imidodiphosphate and forskolin, was not affected by the vitamin D status of the animal. PTH had little effect in activating protein kinase in cells from vitamin D-deficient chicks. In cells from vitamin D-sufficient birds, PTH caused a fourfold increase in adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase. Dibutyryl cAMP inhibited Na+-dependent phosphate uptake by cells from 1,25-(OH)2D3-repleted animals, but the cyclic nucleotide had no effect on phosphate uptake in cells from vitamin D-depleted chicks. This finding suggests that the loss of PTH receptor sites known to be concomitant with the secondary hyperparathyroidism associated with vitamin D deficiency is only a partial explanation for the failure of PTH to inhibit phosphate uptake in cells from vitamin D-deficient animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1984

Efficacy and tolerability of oral acetylcysteine (Fabrol) in chronic bronchitis: a double-blind placebo controlled study.

This multicentre, double-blind, placebo controlled, between-patient study in general practice in the United Kingdom examined the effect of oral N-acetylcysteine (Fabrol) on the symptomatology of patients with chronic bronchitis over a 3-month period. Although improvement in subjective symptoms (sputum viscosity and character, difficulty in expectoration and cough severity) occurred in both treatment groups over the trial period, improvements in difficulty in expectoration and cough severity were greater in patients receiving N-acetylcysteine compared to matching placebo. Trial medication was well tolerated, with a greater number of side-effects attributed to therapy occurring in patients receiving placebo.

Acetylcysteine↗