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Biomedical subjects

G T Peake

Publications and source records attributed to G T Peake.

At least 37 records · Page 2Linked to original sources
PubMed1985

Pituitary-testicular axis dysfunction in burned men.

Plasma total testosterone, free testosterone, LH, and sex hormone-binding globulin (testosterone-estradiol-binding globulin) were measured in adult men hospitalized for treatment of burns. Total testosterone was below the normal range in 37 of 41 patients. Free and total testosterone levels declined very rapidly after the burn, remained low for weeks, and rose toward the end of hospitalization, but usually had not reached normal levels at discharge. The more severe the burns, the lower were the testosterone levels. LH levels were below normal during the first 4 days after the burn and remained in the low or mid normal range thereafter. Sex hormone-binding globulin levels were normal or slightly low. The data suggest the presence of a central defect in the release of LH. Large doses of opiate analgesics or an increase in endogenous opiate peptides related to severe persistent pain might be contributing factors to the pituitary-testicular hypofunction found in burned men.

Adolescent↗
PubMed1985

Prolactin responses to chronic exercise in males.

Chronic, as well as acute, exercise increases circulating PRL in females. The response of males to repeated exercise, however, is unknown. The purpose of the present study was to examine the effects of acute and chronic exercise on plasma PRL levels in untrained males. Eight male subjects performed cycle ergometer exercise at 50% of their maximal oxygen uptake on 10 consecutive days. The subjects exercised in an environmental chamber maintained at 39 degrees C and 30% relative humidity. PRL levels were measured on days 1, 5, and 10 before exercise, and after 20 and 45 minutes of exercise. Acute exercise increased PRL levels. However, plasma levels did not significantly increase during exercise on days 5 and 10. This suggests a similarity in the PRL response to acute exercise in males and females, but a sex difference in the response to chronic exercise.

Adult↗
PubMed1984

Prolactin, amitriptyline, and recovery from depression.

Spontaneous prolactin patterns were determined at 15-min intervals over 5 h in 13 patients, who were suffering from melancholia, during illness and after treatment with amitriptyline. Plasma prolactin levels were significantly greater at most sampling points after patients had recovered than during their illnesses. One patient, who did not recover, showed the opposite trend.

Adult↗
PubMed1984

The value of prolactin dynamics as a predictor of ovulation with bromocriptine in patients with polycystic ovary syndrome.

Six euprolactinemic polycystic ovary syndrome (PCOS) patients were subjected to a 24-hour study with serum sampling every 30 minutes and a perphenazine stimulation test. The serum prolactin (PRL) levels were compared with those of five healthy normoprolactinemic women whose cases were evaluated in a similar fashion. In addition to evaluating the PRL secretory pattern and lactotroph response, the PCOS individuals were given dopamine agonist therapy in a graduated dosage schedule, increasing each month, over a 3-month interval. The PCOS patients exhibited parallel but lower PRL levels than the control subjects during the late evening and early morning hours (P less than 0.0001) and were less responsive to perphenazine at the 6-hour sampling (P less than 0.05). Only one PCOS individual had suggestive evidence of ovulation over the 15 cycles the group was monitored. Therefore, we conclude that euprolactinemic PCOS patients who are nocturnal hyposecretors of PRL and who hyporespond to a perphenazine stimulation test are not likely to ovulate on bromocriptine in the dosages used in this study.

Adult↗
PubMed1983

Effects of androgenic-anabolic steroids on neuromuscular power and body composition.

The effects of androgenic-anabolic steroids on neuromuscular power and body composition were studied in nine volunteers experienced with progressive-resistance weight training. By use of double-blind procedures, testosterone cypionate, nandrolone decanoate, and sesame oil (placebo) were administered in a repeated-measures design that counterbalanced treatment order. Duration of each treatment condition was 3 wk. Supplemental protein was provided, and dietary records were maintained throughout the study. Subjects were trained with progressive-resistance weight-training exercises. Isokinetic dynamometer testing revealed that peak torque output was not significantly changed between treatments in 7 out of 10 isolated-joint actions. The hydrostatic weighing results revealed insignificant differences in lean body mass and percent body fat. Significant changes in some treatment means of three peak torque output tests were insufficient to identify any consistent treatment alterations. Since protein and caloric intake was sufficient to elicit anabolic effects from the steroid treatments and weight-training program, the lack of significant results could not be attributed to dietary considerations. Subjects reported subjective feelings of increased strength after administration of anabolic agents, which may partially account for their widespread use. In conclusion, anabolic steroids did not substantially change body composition or the objective power measurements used in this study.

Adult↗
PubMed1983

Mineralocorticoid modulation of prolactin effect on renal solute excretion in the rat.

The effects of ovine PRL (oPRL) on renal solute and water handling were examined in 1) intact, 2) salt-loaded (6 meq NaCl ip X 8 days), 3) adrenalectomized (adx), 4) adx plus corticosterone-treated (133 micrograms/100 g BW im), and 5) adx plus dexamethasone-treated (10 micrograms/100 g BW im) male rats. After 7 days treatment rats received a water load (3% BW ip) before a 4-h urine collection. Rats also received 0.9% NaCl im (controls) or 1.0 mg oPRL on days 4-7. Treatments were continued to day 8 for inulin clearance determination. The effects of arginine vasopressin (AVP) (173 microU im, days 4-7) on renal solute and water excretion were also examined in salt-loaded rats to see if renal effects of oPRL treatment were due to AVP contamination of the oPRL preparation. In intact rats drinking tap water, oPRL decreased sodium clearance (CNa) and potassium clearance (CK) (P less than 0.05) vs. controls, with no change in free water clearance (CH2O). In intact rats receiving 1.0% NaCl and 1.0% glucose as a replacement for drinking water, oPRL decreased CNa (P less than 0.05) and increased CK (P less than 0.05) vs. controls, with no change in osmolar clearance or CH2O. In salt-loaded rats oPRL increased CNa and CK (P less than 0.05) vs. controls, with no change in CH2O. AVP administration to salt-loaded rats, however, had no effect on CNa and decreased CK vs. controls. oPRL increased CK (P less than 0.05) in adx rats, with no effect on CNa. In adx plus corticosterone-treated rats oPRL decreased CNa and CK (P less than 0.005), similar to its effect in intact animals. oPRL had no effect on renal solute or water excretion as compared to control animals in dexamethasone-treated adx rats. oPRL did not alter glomerular filtration rate at any time. These data suggest that 1) oPRL requires the presence of mineralocorticoids for an effect on sodium, but not potassium, excretion, 2) elevated sodium intake reverses the effect of oPRL on potassium excretion, 3) oPRL potentiates the effects of corticosterone on sodium reabsorption, and 4) glucocorticoids may block the effects of oPRL on the kidney.

Adrenalectomy↗
PubMed1983

Body composition of oligo/amenorrheic athletes.

Menstrual dysfunction in athletes may be related to low body weight or low body fat content. To investigate the relationship between body composition and menstrual function, body composition was evaluated by hydrostatic weighing in two groups of women: 14 athletes with oligo/amenorrhea and 28 athletes with regular menstruation. Age and height were similar in the two groups. In all of the weight parameters, including total body weight, percent ideal body weight, Livi Index, percent body fat, fat weight, and lean body weight, athletes with oligo/amenorrhea were significantly lighter than athletes with regular menstruation. We concluded that menstrual dysfunction in athletes is associated with low body weight, which is comprised of smaller amounts of both fat and lean body mass.

Adipose Tissue↗
PubMed1982

Neonatal treatment with antiserum to prolactin lowers blood pressure in rats.

Prolactin administration reportedly increases blood pressure in rats and rabbits. To study the effects of prolactin deficiency on blood pressure, rats were given saline, normal rabbit serum, or rabbit antiserum to rat prolactin on postnatal days 2 to 5. Both males and females given antiserum had significantly lower blood pressure at 14 weeks than rats given saline or normal rabbit serum. Blood pressure differences between females given antiserum and females given saline disappeared during and following pregnancy. The antiserum also lowered the concentration of prolactin in plasma 49 percent in males and decreased the prolactin response to ether stress in both sexes. These results suggest that endogenous prolactin is involved in blood pressure regulation.

Animals↗
PubMed1982

Hypothalamic adipsia without demonstrable structural lesion.

The clinical and laboratory data of a 5-year-old boy with the syndrome of essential hypernatremia are presented. In a four-year follow-up, no demonstrable hypothalamic structural lesion has been identified. Review of the literature has uncovered four similar cases, suggesting a distinct syndrome of altered hypothalamic function. The syndrome is characterized by: adipsia-hypodipsia (5/5 patients), recurrent hypernatremia (5/5), obesity (4/5), inability to excrete a water load (5/5), lack of growth hormone release in response to provocative stimuli (4/4), blunted thyrotropin releasing hormone responses (3/4), hypothyroidism (2/4), and hyperlipemia associated with hypernatremic crisis (1/1). In one of the patients the syndrome has been attributed to a disturbance of the opioid-peptide system.

Child↗
PubMed1981

Growth and somatomedin-C responses to growth hormone in dwarfed children.

Nineteen children were studied because of short stature. They had in common abnormally low Sm-C values for age, and each received a ten-day course of exogenous GH therapy. Based on their endogenous GH concentrations and the response to GH therapy, in terms of Sm-C and height increments, they were classified into three groups. Group I included patients with GH insufficiency who had blunted GH responses to stimulation, but responded to therapy by normalizing the Sm-C concentration and velocity of growth. Group II patients all had normal GH responses to stimulation, but their responses to exogenous GH were similar to those observed in the GH deficient subjects. In the two children in Group III who had normal release of endogenous GH, Sm-C values and growth rate did not increase in response to GH. Group II patients may represent children with biologically inactive but immunoreactive GH, whereas the children in Group III are examples of the Laron type of dwarfism. Thus, rather than the plasma GH response to provocative stimuli, the Sm-C and growth increment responses to short-term exogenous GH therapy may more precisely identify children that will benefit from long-term GH therapy.

Adolescent↗
PubMed1981

Patterns of spontaneous LH release in normo- and hyperprolactinaemic women.

Hyperprolactinaemia may be associated with functional amenorrhoea. In order to evaluate the possible role of abnormal spontaneous LH secretion in hyperprolactinaemic amenorrhoeic women, plasma LH was measured at 15 min intervals for 300 min in 12 normal women during the early follicular phase of the menstrual cycle and compared to that observed in 11 hyperprolactinaemic amenorrhoeic subjects. Mean plasma prolactin was 9.1 +/- 3.6 ng/ml (X +/- SEM) in the euprolactinaemic and 168 +/- 32 ng/ml in the hyperprolactinaemic group. Sex steroids including oestrone, oestradiol, progesterone and 17-hydroxyprogesterone were similar in the 2 groups. Mean plasma LH levels over the 300 min sampling period were 9.4 +/- 1.6 mIU/ml in the normal subjects and 7.5 +/- 1.0 mIU/ml in the hyperprolactinaemic patients (P greater than 0.10). Every normal woman exhibited at least one LH spike in excess of 10 mIU/ml. Five hyperprolactinaemic patients failed to exhibit any LH spikes above 10 mIU/ml (P less than 0.02 compared to controls). Thus, hyperprolactinaemia was associated with an absence of LH spike activity in 45% of patients studied and this abnormality may play an aetiologic role in the hypogonadism observed in these subjects; in those hyperprolactinaemic subjects with pulsatile LH secretion, however, other explanations for their amenorrhoea should be considered.

Adolescent↗
PubMed1981

The nature of the prostaglandin-producing mononuclear cell in human peripheral blood.

The purpose of this investigation was to identify the human peripheral mononuclear cell responsible for PGE production. The prostaglandin-producing cell had the following characteristics: (1) was glass adherent; (2) was removed by techniques that effectively removed phagocytic cells (carbonyl iron); and (3) was not an E-rosette cell. Furthermore, the peripheral mononuclear cells that contain cytoplasmic PGE by indirect immunofluorescence also ingest latex particles. B and T lymphoid cell lines did not produce large quantities of PGE. Mononuclear cells separated on discontinuous BSA gradients varied greatly in their ability to produce prostaglandin (low density > high density). These data constitute strong evidence that the majority of PGE produced in peripheral mononuclear cell suspensions emanates from a population of low-density monocytes.

Cell Adhesion↗
PubMed1980

Differential lipemic and proteinemic response to oral ethinyl estradiol and parenteral estradiol cypionate.

Oral synthetic estrogen administration to normal women has been shown to result in both a lipemic and a proteinemic response. To determine whether parenteral estrogen administration would have similar results, the effects of intramuscular depo-estradiol cypionate on serum lipids and ceruloplasmin were examined. The oral and parenteral estrogens chosen for this study are frequently used therapeutically and varying doses in the range of those commonly employed clinically were given to the experimental subjects. Following oral ethinyl estradiol (20, 50, and 100 micrograms every 12 hr) comparable and significant increases in triglyceride (73 +/- 6 to 128 +/- 10 mg/dl, p < .001), ceruloplasmin (87 +/- 4 to 188 +/- 11 mg/dl, p < .001), and HDL-cholesterol (60 +/- 2 to 74 +/- 3 mg/dl, p < .001) were observed. In contrast, despite substantial increases in serum estrogens, parenteral estrogen administration (depo-estradiol cypionate, 5 and 10 mg) failed to result in alterations in any of the measured parameters. Thus, the route and/or type of estrogen administered may determine the proteinemic and lipemic effects of estrogen in man.

Administration, Oral↗