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Biomedical subjects

J L Barron

Publications and source records attributed to J L Barron.

At least 55 records · Page 3Linked to original sources
PubMed1987

Comparison of serum calcium fractions during haemodialysis and peritoneal dialysis.

Total, ultrafiltrable and ionised calcium concentrations were determined in anaerobic serum from healthy volunteers, patients immediately before and after haemodialysis and patients on continuous ambulatory peritoneal dialysis (CAPD). Protein-bound, complexed and albumin-corrected total calcium concentrations were calculated from the results. During haemodialysis, complexed calcium did not change, whereas the other fractions increased. For patients on CAPD, the total, ionised and protein-bound calcium results were frequently lower than the reference group, whereas the ultrafiltrable and albumin-corrected total calcium results were within or higher than the reference group. Albumin-corrected total calcium for all subjects correlated better with ultrafiltrable calcium than with ionised calcium. It was concluded that low ionised calcium concentrations found in CAPD patients may be related to low albumin concentrations, and the concentration of physiologically active calcium may be normal in these patients.

Adult↗
PubMed1986

Cushing's syndrome in pregnancy. A case report.

A case of Cushing's syndrome caused by a right adrenal adenoma in a 16-week gravid patient is reported. After right adrenalectomy she was maintained on replacement doses of hydrocortisone, and at 38 weeks' gestation a healthy but small-for-gestational age infant was delivered vaginally.

Adenoma↗
PubMed1986

Parameters of the event-related potential are related to functioning in the mentally retarded.

Event-related potentials were measured in 39 institutionalized profoundly and severely retarded clients divided into two groups: clients assigned to sheltered workshop (WS); and clients, residentially matched, but not assigned to workshop (NSW). Since the groups differed in intelligence (p less than 0.01) the ERP was evaluated by analysis of covariance with IQ as the covariate. The WS group had significantly shorter latency of components reflecting initial registration (P1) and channeling (N1) of sensory input and significantly greater amplitude of indices of enhanced perception (P2) and cognitive elaboration (N2). The WS group had significantly more complex waves than the NWS group. A modest (r=0.31, p less than 0.05) relationship between P2 and IQ was observed. Multiple correlations of composite measures of the ERP with IQ were not significant but higher in the NWS than WS group. The possibilities that the ERP be used as a supplemental metric for functional evaluation or that the workshop experience might stimulate central nervous system plasticity were discussed.

Adult↗
PubMed1985

Disregulation of hypothalamic-pituitary-adrenal axis in the mentally retarded.

Previous reports of cognitive and social improvement in the mentally retarded after administration of MSH/ACTH fragments suggested disregulation of the hypothalamic-pituitary-adrenal (HPA) axis. The current study examined the integrity of this system with the Dexamethasone Suppression Test (DST). The DST is a biological index of HPA integrity and recently has been used as a diagnostic aid for endogenous depression. Thirty-five mentally retarded patients were administered 1 mg of dexamethasone just after a sample of blood was taken. Blood samples were analyzed for cortisol by RIA at 11:00 p.m. (basal), 8:00 a.m., 4:00 p.m., and 10:00 p.m. Between 40% and 48% (depending on sampling) of the patients failed to suppress cortisol (greater than 4 micrograms/dl), after the DST challenge. The results suggested that a significant proportion of mentally retarded patients have a DST index reflecting a disordered HPA axis and complements earlier studies of cognitive enhancement observed after treatment with MSH/ACTH fragments. The possibility that the stress of hospitalization was related to a disordered HPA was suggested. The possible co-existence of depression in the mentally retarded invites further study.

Adult↗
PubMed1985

Hypothalamic dysfunction in overtrained athletes.

Some athletes who undertake strenuous training programs for a prolonged period of time develop the overtraining syndrome. The pathophysiology of the condition is unknown. Hypothalamic-pituitary function was studied by determining the hormonal responses to insulin-induced hypoglycemia in five asymptomatic male marathon runners during a 4-month period in which they ran 42-, 56-, and 92-km races and in four overtrained male athletes. The response of the asymptomatic runners was not different when tested 1 month before and within 48 h after the 42- and 92-km races. All four overtrained athletes presented with impaired training and racing times, apathy, and a heavy-legged feeling and were tested when overtrained and again after 4 weeks of rest. The plasma cortisol, ACTH, GH, and PRL responses to insulin-induced hypoglycemia in the four overtrained athletes were lower than their responses after the rest and lower than the responses of the asymptomatic runners. In both groups, the LH, TSH, and PRL responses to LHRH and TRH were normal. The impaired hormonal responses to insulin-induced hypoglycemia, with recovery after 4 weeks of rest, indicate hypothalamic dysfunction and may be a diagnostic marker of the overtraining syndrome.

Adrenocorticotropic Hormone↗
PubMed1984

Salivary cortisol assessment in the evaluation of hypothalamic-pituitary-adrenal function.

A simple, short and sensitive direct radio-immunoassay technique for the determination of salivary cortisol concentration was employed to assess saliva as a medium for evaluating cortisol response during endocrine testing in 9 controls and 40 patients. Results in controls suggested that an adequate salivary cortisol response to insulin hypoglycaemia was an increase of 150% above the basal value with a minimum peak of 15 nmol/l. Thirty-three patients were classified as being either good or poor responders to insulin hypoglycemia on the basis of criteria for plasma cortisol levels. When the defined salivary cortisol response was used for assessment, all 33 patients were correctly categorized into the same response groups. The salivary cortisol response to intramuscular tetracosactrin in 3 patients and an intravenous dexamethasone infusion in 4 patients confirmed the value of saliva as an assay medium. These studies show that the salivary cortisol response parallels that of total plasma cortisol in all cases. However, with sampling at short intervals a lag in secretion of the free fraction from the plasma into the saliva becomes apparent. The relative change in cortisol levels from the basal value is greater in saliva than in plasma.

Adult↗
PubMed1984

Self-injurious behavior and stereotypy in an institutionalized mentally retarded population.

Demographic variables and behavioral characteristics of institutionalized mentally retarded clients exhibiting both self-injurious behavior (SIB) and stereotypy, stereotypy alone, SIB alone, or neither of these behaviors were analyzed. Overall, there were no significant differences for the demographic variables measured. Multivariate analyses revealed that severity and frequency of behavior, sensory handicap, and sex of the subject were the best predictors of group membership. Moreover, this research suggests that SIB and stereotypy can be classified as stereotyped SIB and withdrawal stereotypy, respectively. Thus, the treatment modalities presently being applied to these behaviors could be inappropriate. Additional evidence is discussed that supports the belief that an organic physiological substrate or mechanism could be related to these aberrant behavior patterns, which would necessitate a new diagnostic classification and alternative forms of treatment.

Adolescent↗
PubMed1984

Arginine hydrochloride stimulation of serum potassium and aldosterone is enhanced by somatostatin-28.

Potassium, aldosterone and insulin responses to arginine infusion were compared in 5 normal men during infusions of somatostatin-14 (SS-14), somatostatin-28 (SS-28) and a control infusion. SS-14 and SS-28 were infused continuously at a rate of 8.6 pmol/min/kg and arginine (0.5 g/kg) was infused from 30-60 min. Following the control infusion with arginine hydrochloride, serum aldosterone and potassium levels increased slightly. The rise in potassium appears to be due to an exchange of cellular potassium for the proton from the arginine hydrochloride. SS-14 had no significant effect on serum potassium or aldosterone but an equimolar dose of SS-28 significantly enhanced the rise in potassium and aldosterone. SS-28 completely inhibited the arginine-stimulated insulin increase while SS-14 only partially inhibited the insulin increase. Since insulin opposes the increase in serum potassium by stimulating cellular uptake of this cation, the enhanced rise in serum potassium in response to arginine hydrochloride during the SS-28 infusion is likely due to the potent insulin suppressing effect of SS-28. The rise in serum aldosterone is directly related to the degree of elevation of serum potassium. These findings caution against the infusion of SS-28 during an arginine stimulation test.

Acid-Base Equilibrium↗
PubMed1983

The effect of disulfiram on the urinary excretion of catecholamine metabolites in alcoholic males.

The urinary excretion of vanillylmandelic acid (VMA), homovanillic acid (HVA) and total metanephrines (TMNs) was studied in a group of White male alcoholic patients under three experimental conditions--on admission and prior to treatment, after 7 days of administration of a placebo, and after 9 days of administration of disulfiram 400 mg/d Disulfiram caused a significant decrease in VMA levels compared with the pretreatment (P less than 0,01) and placebo (P less than 0,05) levels. The output of HVA and TMNs was unchanged. It is suggested that disulfiram may produce false-negative results in cases of suspected phaeochromocytoma if VMA levels only are assayed. TMNs would appear to be the measurement of choice in such a situation.

Adult↗
PubMed1983

Somatostatin-28 and somatostatin-14 suppression of arginine-, insulin-, and TRH-stimulated GH and PRL secretion in man.

GH and PRL responses to arginine infusion and to the combined pituitary stimulation test (0.1 u/kg of insulin, 200 micrograms of TRH, 100 micrograms of LHRH) were compared in five normal men during infusions of somatostatin-14 (SS-14) and somatostatin-28 (SS-28), and during control infusions of vehicle alone. SS-14 and SS-28 were infused at a rate of 1.8 nmol/kg over 210 min. Arginine (0.5 g/kg) was infused from 30 to 60 min and the combined pituitary stimulation test commenced at 120 min. Arginine (0.5 g/kg) infused from 30 to 60 min induced an increase in GH secretion in all subjects and this increase was completely abolished in these same subjects when infused with SS-14 and SS-28. Arginine-induced hyperglycaemia was significantly greater during infusion of SS-14 and further enhanced by infusion of SS-28. A small increase in PRL secretion occurred after arginine infusion and this was not inhibited by SS-14 or SS-28. Insulin and TRH administration induced marked increases in both GH and PRL secretion. The mean GH increase was significantly inhibited by SS-14 and SS-28 up to 165 min but not thereafter. The PRL increase was significantly inhibited by SS-28 but not by SS-14 and this greater efficacy was also indicated by administering different doses of SS-28 to one subject. Taken together with the demonstration that SS-28 is released from the median eminence, these findings indicate that SS-28 has a hormonal role in the regulation of GH and PRL secretion.

Adult↗
PubMed1983

Inhibition of pancreatic hormone secretion by somatostatin-28 and somatostatin-14 in man.

The effects of a 210 min infusion of 1.8 nmol/kg somatostatin-14 (SS-14), somatostatin-28 (SS-28), and vehicle (Haemaccel) alone, on arginine- and insulin-stimulated release of pancreatic hormones were tested in 5 normal male subjects. Arginine administered at 30-60 min induced an increase in plasma glucose concentrations which was enhanced by SS-14 and further increased by SS-28. SS-28 was more effective than SS-14 in suppressing the arginine-induced secretion of insulin. Arginine-stimulated and insulin-stimulated (at 120 min) glucagon release was equally suppressed by SS-14 and SS-28, as was insulin-stimulated pancreatic polypeptide secretion. At the end of the SS-14 infusion the mean plasma somatostatin level was approximately 28% of that which occurred during the SS-28 infusion. The results are discussed in relation to similar studies in vitro and in vivo in laboratory animals and to a possible role of the two forms of SS in carbohydrate homeostasis.

Adult↗
PubMed1982

Somatostatin-28 inhibits thyroid-stimulating hormone release in man.

The effects of an equimolar (1,8 nmol/kg body weight) infusion of somatostatin-28 (SS-28) and somatostatin-14 (SS-14) on the thyroid-stimulating hormone (TSH) response to a combined pituitary function test consisting of 200 micrograms thyrotrophin-releasing hormone (TRH) as well as 100 micrograms luteinizing hormone-releasing hormone (LH-RH) and insulin 0.1 U/kg were compared in 5 normal men. SS-28 significantly inhibited the TSH response to TRH compared with the control infusion. SS-14 was ineffective in 1 subject but overall did not differ significantly from SS-28. In 1 of the subjects the inhibitory effects of SS-28 on the TSH response was determined at three different doses of SS-28. In this subject SS-28 was found to be approximately 16 times more potent than SS-14 in the inhibition of TSH release. Suppression of TSH by SS-28 adds further support for a hormonal role for the peptide.

Adult↗
PubMed1982

Cerebrotendinous xanthomatosis: a defect in cellular sterol biosynthetic control.

A mentally retarded woman with tendon xanthomata and normal serum cholesterol concentration was found to have raised cholestanol concentrations in the serum and in a xanthoma. This confirmed the diagnosis of cerebrotendinous xanthomatosis (CBX). No specific lipoprotein fraction was found to transport cholestanol. For the first time cultured fibroblasts from a patient with CBX were found to accumulate cholestanol.

Brain Diseases↗
PubMed1982

Metabolic clearance and plasma half-disappearance time of D-TRP6 and exogenous luteinizing hormone-releasing hormone.

The MCR and t1/2 of D-Trp6 LRH, a potent analog of LRH, were compared to those of exogenous LRH. Studies were performed on eight normal subjects during and after cessation of a constant infusion of D-Trp6 LRH and LRH. The D-Trp6 LRH and LRH were quantitated individually by sensitive and specific RIAs which did not cross-react with the other peptide infused or fragments of the degraded peptides. High performance liquid chromatography of plasma from a patient infused with D-Trp6 LRH alone yielded one peak, which coeluted with D-Trp6 LRH. The kinetics of peptide clearance were biphasic, with a rapid and a slow component of elimination. The t1/2 of the rapid component of D-Trp6 LRH clearance was 18.7 +/- 1.8 (SEM) min. This was significantly longer (P less than 0.001) than the t1/2 for the LRH of 7.8 +/- 1.1 min. The MCRs for D-Trp6 LRH and LRH were 503.4 +/- 196.4 and 1766.6 +/- 404.3 ml/min, respectively (P less than 0.01). The longer t1/2 of D-Trp6 LRH compared to that of LRH reflects the slower clearance, which is probably due to a decreased rate of degradation. These findings indicated that the enhanced bioactivity of D-Trp6 LRH is in part due to a decreased rate of degradation.

Adult↗