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Biomedical subjects

H E Carlson

Publications and source records attributed to H E Carlson.

At least 73 records · Page 4Linked to original sources
PubMed1980

Role of growth hormone in experimental phosphorus deprivation in the rat.

The demands of growth are known to exacerbate the effect of phosphorus deprivation (PD). We examined whether changes associated with PD could be prevented in young rats in which growth and growth hormone (GH) were eliminated by hypophysectomy (HPX) and whether PD in normal intact rats (INT) was associated with increased secretion of GH. INT or thyroxine- and ACTH-replaced HPX rats were fed one of the three diets: 0.31% P (NP); 0.027% P (LP), and 0.31% P, pair-fed with LP-mates (NP-PF). The results indicate that HPX did not qualitatively alter several physiologic responses to PD: (a) serum and urinary phosphorus (P) decreased and urinary calcium (Ca) increased; (b) net intestinal Ca retention fell and duodenal sac uptake of 45Ca rose; and (c) external P balance was restored and duodenal sac uptake of 32P-phosphate increased. Only the hypercalcemia seen in INT, LP rats was prevented by HPX. In INT rats serum immunoassayable GH levels, measured in single samples, were not different between different dietary groups while pituitary bioassayable GH was reduced in both LP and NP-PF rats when compared to the NP rats. Thus, except for hypercalcemia, the physiologic responses associated with PD are not prevented by the elimination of growth and GH, and the development of these responses in INT rats was not associated with a consistent or specific alteration in GH secretion.

Animals↗
PubMed1980

Persistence of spermatogenesis in hypogonadotropic hypogonadism treated with testosterone.

The case histories are reported of two patients who had persistent spermatogenesis as evidenced by normal semen analyses and fertility in the face of hypogonadotropic hypogonadism and testosterone administration. When not receiving testosterone, both men consistently had normal or low serum gonadotropin levels. Since pooled serum testosterone levels were low simultaneously, these "normal" gonadotropin values are still consistent with hypogonadotropic hypogonadism. Standard testosterone replacement therapy maintained secondary sex characteristics and, surprisingly, spermatogenesis in both men. A review of the literature revealed conflicting evidence concerning the roles of gonadotropins and testosterone in affecting spermatogenesis. In applying this evidence to our patients, it appears that gonadotropins may have only a minimal role in maintaining fertility in patients with established spermatogenesis and "adequate" testosterone levels; it also appears that relatively low doses of exogenous testosterone may maintain or enhance spermatogenesis in certain individuals. We conclude that men with acquired hypogonadotropic hypogonadism should not be presumed to be sterile and that a larger study of fertility in these patients is necessary. Until then, we recommend that the semen of these patients be analyzed at the time of diagnosis and during treatment with testosterone.

Adult↗
PubMed1980

Studies on the role of histamine in human pituitary function.

To elucidate further the role of histamine in pituitary regulation, TRH and L-DOPA stimulation tests were performed with and without diphenhydramine, cimetidine, or betazole pre-treatment. Betazole blunted the GH response to L-DOPA and slightly enhanced the T3 response to TRH without altering the TSH or PRL increments. Neither diphenhydramine nor cimetidine had any acute effect on the hormonal responses examined. Histamine apears to play only a limited role in these aspects of human pituitary regulation.

Adult↗
PubMed1980

Failure of bombesin to alter anterior pituitary hormone secretion in man.

Because of the stimulating effects of bombesin on growth hormone and prolactin secretion in the rat, we have studied the effects of bombesin infusions on anterior pituitary hormone secretion in man. Biological activity of the infused bombesin was confirmed by observing a brisk increase in serum gastrin concentrations and in gastric acid secretion during the lowest dose of bombesin infused. We could demonstrate no effect of bombesin in doses fro 200-600 pmol.kg-1.h-1 on growth hormone, prolactin, thyrotrophin, luteinizing hormone and follicle stimulating hormone.

Bombesin↗
PubMed1980

Immunological and biological studies on cholecystokinin in rat brain.

Cholecystokinin-like immunoreactivity (CCK-LI) was demonstrated by radioimmunoassay in aqueous (n = 3) and acid (n = 10) extracts of cortex (42 +/- 9 pmol/g; 4.0 +/- 1.8 pmol/g), thalamus (4.1 +/- 1.1 pmol/g; 1.0 +/- 0.2 pmol/g), and hypothalamus (58 +/- 14 pmol/g; 6.3 +/- 0.7 pmol/g). Sephadex chromatography revealed that more than 95% of the immunoreactivity in acid extracts coeluted with CCK33 standard. In aqueous extracts more than 80% of immunoreactivity coeluted with CCK8 standard. Both the CCK33- and CCK8-like materials induced contraction of guinea pig gallbladder in vitro. L-Tryptophan (200 mg/kg) and high-dose morphine (20 mg/kg) decreased CCK33-LI concentrations in hypothalamus and thalamus. Low-dose morphine (5 mg/kg) decreased CCK33-LI in hypothalamus. We conclude that 1) CCK-LI is present in cortex, thalamus, and hypothalamus of the rat brain, 2) CCK-LI exists in two predominant molecular forms coeluting with CCK33 and CCK8, 3) both molecular forms are biologically active, and 4) concentrations of rat brain CCK33-LI are modulated by serotonergic and opiate mechanisms.

Animals↗
PubMed1980

Autofeedback of prolactin in cultured prolactin-secreting pituitary cells.

Cultured GH3 rat pituitary tumor cells which secrete prolactin (PRL) were used to study autoregulation of rat PRL (rPRL) secretion. Acute (1 h) release of rPRL by cells in monolayer culture was inhibited by ovine PRL (oPRL; 10(-7) and 10(-8) M). Intracellular rPRL accumulation was not inhibited by exogenous oPRL. No effect of oPRL was seen during long-term (12-day) incubation of cells with oPRL (10(-7) to 10(-9) M). oPRL exerts an acute suppressive effect on rPRL release at the cellular level, but does not inhibit rPRL synthesis or long-term release.

Animals↗
PubMed1979

Thyrotropin-releasing hormone and thyroid hormones in amniotic fluid.

Immunoassayable TRH (iTRH) was measured in 50 amniotic fluid specimens with a mean concentration of 207 +/- 26 (SE) pg/ml. This iTRH demonstrates parallelism with the standard curve for synthetic TRH. With increasing gestational age there is an increase in iTRH levels in amniotic fluid with a decrease in 3,3',5'-triiodothyronine levels (rT3), while thyroxine levels (T4) remain unaltered. Preliminary data suggest that iTRH levels in amniotic fluid that are less than 150 pg/ml after 32 weeks of gestation may correlate well with low Apgar scores at birth. There was no correlation of rT3 or T4 amniotic fluid levels with the Apgar scores.

Amniotic Fluid↗
PubMed1979

Pituitary and peripheral resistance to thyroid hormone.

A 32-year-old Caucasian male, clinically euthyroid, with paranoid schizophrenia and granulocytopenia, had elevated total and free serum T4 and T3; serum TSH was normal (2.7 +/- 0.7 micronU/ml). There was no goitre present, no evidence of Graves' disease, and no evidence of pituitary tumour. He had a normal response to methyl-TRH, with a TSH increment of 14.6 micronU/ml, T3 increment of 212 ng/dl, and T4 increment of 4.7 microgram/dl; baseline value and decreased the TSH increment in response to methyl-TRH. T3 therapy (100 microgram/day) decreased the thyroidal radioactive iodine uptake to less than half the baseline prolactin was normal with a normal response to methyl-TRH to 4.1 micronU/ml. Iodine therapy caused an increase in his baseline TSH with an increase in the TSH response to TSH. The metabolic clearance rates (MCR) and production rates (PR) of T3 and T4 were increased. Baseline serum levels of glycoprotein hormone alpha-subunit were normal and showed a slight increase in response to methyl-TRH, similar to normal subjects. This patient has evidence of partial pituitary and peripheral resistance to thyroid hormone; his only evidence for hyperthyroidism is the elevated MCR and PR of T3 and T4.

Adult↗
PubMed1979

Effect of chronic metoclopramide therapy on serum pituitary hormone concentrations.

The effect of chronic (3--9 months) therapy with metoclopramide on serum levels of pituitary and thyroid hormones was studied in 4 males and 1 female. The mean serum prolactin concentration during metoclopramide therapy was significantly higher than after discontinuation of metoclopramide. Serum prolactin concentrations increased acutely after each dose of metoclopramide. Serum prolactin concentrations increased acutely after each dose of metoclopramide, and gradually returned to normal by 6--12 h. There was no sifgnificant differences in the serum TSH, T3, T4, GH, and gonadotrophin levels during and after metoclopramide administration. In the male subjects the mean serum testosterone was normal, but significantly lower during metoclopramide therapy.

Adult↗
PubMed1979

Effect of endogenous hyperprolactinemia on human lower esophagel sphincter pressure.

The cause of gastroesophageal reflux occurring during pregnancy is not completely understood but may be related to changes in the hormonal environment specifically related to pregnancy. To evaluate the possible role of prolactin, one of the hormones elevated during pregnancy, we studied the effect of endogenously elevated serum prolactin concentrations, induced by I.V. thyrotropin-releasing hormone (TRH), on lower esophageal sphincter pressure (LESP) in normal subjects. Elevated prolactin concentrations (P less than 0.0001), did not change LESP over a 60-minute period. Serum gastrin concentration did not change significantly at any time during the study. We conclude: 1. acute elevations of serum prolactin comparable to the concentrations that occur during pregnancy did not change LESP; 2. there is no evidence that the hypothalamic regulating factor TRH affects serum gastrin concentration in man.

Adult↗