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Biomedical subjects

J E Tyson

Publications and source records attributed to J E Tyson.

At least 19 recordsLinked to original sources
PubMed1979

Plasma thyrotropin-releasing hormone, prolactin, thyrotropin, and thyroxine concentrations following the intravenous or oral administration of thyrotropin-releasing hormone.

In a further evaluation of the use of oral thyrotropin-releasing hormone (TRH) in puerperally lactating women, a radioimmunoassay for its measurement has been developed. Its concentration in plasma as well as that of prolactin (PRL), thyrotropin (TSH) and thyroxine (T4) were measured following either intravenous or oral administration of TRH. Basal concentrations of TRH in 14 normally cycling women ranged from less than 5 to 17 pg/ml. Two luteal phase studies produced peaks in plasma TRH 5 to 10 minutes after 100 micrograms of TRH administered intravenously with a return to basal concentrations within 2 to 3 hours. In 10 normally menstruating women, ingestion of 10 mg of TRH orally resulted in plasma TRH which peaked at 423 +/- 123 pg/ml (standard error of the mean) at 30-minutes. Plasma PRL, TSH, and T4 also increased and remained slightly elevated at 4 hours. These 8-hour studies were performed in a puerperal lactating woman who had ingested 10 mg of TRH orally twice a day for 7 days prior to blood sampling. TRH concentrations declined throughout each day while TSH rose slightly in the first 1 to 2 hours but remained within normal limits. The prolonged administration of 10 mg of TRH orally twice daily to three puerperally lactating women resulted in elevations in plasma TRH 2 to 3 hours following hormone administration, yet no significant increases in plasma TSH were observed. Both endogenous TRH and TSH were measured before and after 22 nursing events in nine puerperally lactating women. There was no change in the concentration of either substance and all values were similar to those obtained in normally menstruating women.

Administration, Oral↗
PubMed1979

The relative significance of human placental lactogen in the diagnosis of retarded fetal growth.

The purpose of this prospective study was to determine whether serial maternal venous hPL determinations could identify pregnancies resulting in growth-retarded infants from a selected population at presumed high risk for IUGR. Our results demonstrated that mean hPL levels in IUGR outcome pregnancies were significantly lower than normal after 33 weeks' gestation. Mean hPL was also lower in some pregnancies resulting in normal-weight neonates with abnormally low PI or short CHL, suggesting that these neonates, despite normal birth weight achievement, may represent previously unsuspected.

Birth Weight↗
PubMed1979

Further evidence for the role of prolactin on human fetoplacental osmoregulation.

The addition of ovine prolactin (oPRL) to the fetal side of human term amnion in vitro is associated with a decrease in membrane permeability to tritiated water (THO). As the concentration of oPRL is increased from 2.5 to 20.0 micrograms per milliliter, permeability is progressively impaired. The addition of a specific prolactin receptor antibody completely abolished the effect of oPRL. Also, the addition of Ouabain abolished the effect of oPRL. When an osmolic gradient was created using Dextran-10 on the maternal side of the amnion, the bulk flow of water in control and 3PRL-treated membranes was not significantly different. These findings suggest that PRL acts predominantly on the diffusional flow rather than the bulk flow of water across amnion and that it is a transcellular transport. These studies also represent indirect evidence for the existence of prolactin receptor sites at the level of the amnion.

Amnion↗
PubMed1979

Patterns of intrauterine growth retardation.

A prospective study of 70 singleton pregnancies at high risk for intrauterine growth retardation (IUGR) was undertaken to determine 1) the differences in intrauterine growth patterns; 2) the diagnostic accuracy of obstetric techniques; and 3) the frequencies of perinatal complications. Thirty infants displayed signs of IUGR. Although only 14 infants had low birth weights, these 14, as well as the remaining 16 infants under study, displayed many other features of growth abnormalities, including a low ponderal index, short stature, and small head circumference. These data demonstrate various patterns of IUGR. Although the perinatal complications occurred primarily in the low-birth-weight group, the major growth abnormalities observed in the non-low-birth-weight group demonstrate the need for additional short- and long-term follow-up studies in both groups.

Adult↗
PubMed1978

Prolactin-secreting tumors and hypogonadism in 22 men.

We studied 22 men with prolactin-secreting pituitary tumors and hypogonadism. Twenty complained of impotence, nine had visual impairment, and three experienced galactorrhea. None of the 17 patients undergoing operation or radiotherapy, or both, were subsequently normoprolactinemic. In all 13 patients treated with bromocryptine major clinical improvement was associated with a decrease in serum prolactin levels and in nine with an increase in serum testosterone. Two patients receiving testosterone replacement therapy showed improved potency only after bromocryptine was administered. The results indicate that hyperprolactinemia frequently induces hypogonadism in men, that bromocryptine ameliorates symptoms of disease previously unchanged by operation or radiotherapy, and that the impotence observed may not be solely the result of hypogonadism.

Adenoma, Acidophil↗
PubMed1978

Plasma dopamine-beta-hydroxylase activity and norepinephrine levels during the human menstrual cycle.

Plasma samples obtained throughout the normal menstrual cycles of six women were analyzed for dopamine-beta-hydroxylase activity (DBH), norepinephrine (NE), follicle-stimulating hormone, luteinizing hormone, and prolactin. Neither DBH activity nor NE concentrations paralleled changes in plasma gonadotropins and prolactin. No consistent pattern of either plasma DBH activity or NE concentrations during the normal menstrual cycle was noted. Thus, an association between peripheral sympathetic nervous system activity and the midcycle surge in plasma gonadotropins reported by others was not reproducible in our study of normally menstruating women.

Dopamine beta-Hydroxylase↗
PubMed1978

Nursing-mediated prolactin and luteinizing hormone secretion during puerperal lactation.

Alterations in plasma prolactin (PRL) concentrations in response to nursing in puerperally lactating women are often significant beyond the 90th postpartum day, yet the increment appears unrelated to the frequency or duration of the nursing stimulus. Tonic gonadotropin secretion is low, assuming a more episodic secretory pattern either when the frequency of breast-feeding is reduced or when weaning takes place. Significant increments in peripheral concentrations of luteinizing hormone can be seen in response to weaning coincident with a fall in peripheral plasma PRL concentration. At the same time, peripheral estrogen concentrations increase, suggesting that a specific set point for ovarian responsiveness to gonadotropins exists. Whether this set point is related solely to the peripheral concentration of gonadotropins or whether it is also related to the peripheral PRL concentration is not known at this time.

Female↗
PubMed1977

Prolactin and fetal osmoregulation: water transport across isolated human amnion.

The addition of human or ovine prolactin to the fetal side of the human amnion is associated with a latent decrease in membrane permeability. The specificity of this effect of prolactin is observed when equimolar concentrations of human placental lactogen and human growth hormone were used in place of ovine prolactin and failed to influence water transport. Likewise, the extracellular transport of p-aminohippurate across human amnion was unaffected by the addition of ovine prolactin. Tritiated water transport under these circumstances, however, remained impaired. The addition of antibody to ovine prolactin completely blocked the effect of this polypeptide on membrane permeability. Permeability to tritiated water remained unchanged when synthetic arginine vasopressin was added to the fetal side of the amnion. The results imply an active role for prolactin on water transport across human amnion. Moreover, the latent period between the addition of the polypeptide and its subsequent influence on permeability suggests a biologic effect of this hormone. That this effect is related to ion transfer remains to be shown.

Amnion↗
PubMed1977

Adrenocortical function in hyperprolactinemic women.

To study the effects of prolactin (PRL) on adrenocortical function in humans, dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), androstenedione (delta) and testosterone (T) were measured in serum obtained from 35 hyperprolactinemic women with galactorrhea and amenorrhea before and after treatment with bromocriptine-induced fall in mean PRL levels from 82 +/- 8 (SE) to 14 +/- 2 ng/ml (n = 39, P less than 0.0005), DHAS fell from 322 +/- 21 to 237 +/- 21 microgram/dl (n = 39); P less than 0.0005), DHA fell from 492 +/- 47 to 378 +/- 30 ng/dl (n = 39; P less than 0.01) while T (n = 16) and delta (n = 13) levels were unchanges (44 +/- 4 vs. 49 +/- 4 ng/dl and 280 +/- 55 vs. 236 +/- 40 ng/dl, respectively). In addition, 4 women were infused iv with 25 microgram synthetic ACTH over 4 h and serial blood samples drawn while hyperprolactinemic, and again 2-4 months later following normalization of PRL levels by bromocriptine. Although pre-infusion levels of DHAS were lower when PRL levels were normalized, no significant differences in responses of circulating DHAS, DHA, T, cortisol and 17-hydroxyprogesterone concentrations were detected between the two infusions. Since DHAS is virtually an exclusive product of the adrenal cortex, and since high PRL levels appear to inhibit ovarian steroid production, the findings suggest that hyperprolactinemia selectively stimulates adrenocortical androgen production.

Adrenal Cortex Hormones↗
PubMed1977

Hypoglycemia in man pathologic and physiologic variants.

To determine if an effective method existed for distinguishing the physiologic hypoglycemia of fasting from pathologic hypoglycemia, 72-hour fasts were conducted in 60 women and 20 men of normal weight, in 16 obese subjects, and in six of 11 patient with insulinomas. Only the pattern of change of the immunoreactive-insulin-to-glucose ratio (the I/G ratio), calculated at major time intervals of the fast, provided a clear-cut distinction between these groups; plasma glucose values alone could not make this distinction. The mean fasting I/G ratio was calculated for each subject from that subject's I/G ratios at 12-hour intervals during the fasting period. In no single case did the mean I/G ratio during fasting for an individual of normal weight equal or exceed the control I/G. I/G ratios increased dramatically during fasting in each patient with an insulinomas. Normal obese patients (15% greater than ideal body weight) did not provide a diagnostic problem, since, regardless of sex, glucose values of less than 55 mg/dl. did not occur. Although the pattern of change of the I/G ratio was extremely useful, the basal I/G ratio alone was potentially misleading; this was due to overlap of basal I/G ratios between subjects with simple obesity and patients with insulinomas. In addition, absolute values for the I/G ratio varied with the technique employed for measuring glucose and insulin. Change of the I/G ratio, however, was independent of the techniques used for measuring glucose and insulin. DIABETES 26:161-65, March, 1977.

Adenoma, Islet Cell↗
PubMed1976

Endocrine-metabolic response to acute starvation in human gestation.

During a 72 hour fast in pregnant women, significant decrements in the maternal plasma glucose concentrations, accompanied by a significant increase in the plasma placental lactogen (hPL) concentration, occur. At the same time, utilization of glucogenic amino acids, principally alanine, takes place. The mean postprandial glucose concentration in pregnancy is significantly lower than that of comparable nonpregnant women (70.5 +/- 1.7 versus 79.5 +/- 1.3 mg. per 100 ml., p less than 0.001). There appears to be a significant sparing effect on the maternal plasma glucose concentration during acute fasting which may be mediated through hPL. Concentrations of amniotic fluid and fetal plasma glucose from women undergoing fasting decrease in a manner parallel to that of the mother. Fasting provokes a mean rise in plasma hPL of 33.2 per cent over basal levels. This rise is still evident 72 hours after refeeding, after which it gradually returns to pretest concentrations. The infusion of alanine or arginine to pregnant women at the end of the fast produced increments in the peripheral maternal glucose concentration. The response was much greater with alanine than with arginine, demonstrating the increased gluconeogenic potential of this amino acid. The increment in human growth hormone (hGH) following alanine infusion was significantly greater than that observed after arginine administration. Hypoaminoacidemia was present in nonpregnant and pregnant women in response to fasting, but the decline was greater in pregnancy. Acute fasting in the first half of gestation appears to produce significant alterations in carbohydrate metabolism evidenced by profound hypoglycemia, hypoinsulinemia, and hypoaminoacidemia. This maternal deficit can be reflected in fetal substrate concentrations. The effect of these changes on fetal growth and development is speculative at this time.

Abortion, Therapeutic↗
PubMed1976

Gestational and pregestational diabetes: an approach to therapy.

The objective of management in the pregnant diabetic patient is to achieve physiologic glucose homeostasis through the use of diet and insulin. As outlined, the numerous ancillary tests developed during the past 15 years to assist the clinician in determining impending fetal death have left much to be desired, especially where metabolic homeostasis has not been achieved prior to the thirty-sixth week of gestation. The statistics from this institution indicate that the maintenance of the plasma glucose concentration below 100 mg. per cent throughout gestation, regardless of the severity of the diabetes, all but removes the risk of maternal-fetal complications due to diabetes. The management is uniform for all patients exhibiting an abnormality of carbohydrate metabolism, and, although it is rather difficult to accept, there have been minimal neonatal complications when the protocol outlined in this presentation has been followed.

Adolescent↗
PubMed1976

Galactorrhea-amenorrhea: psychological interaction with neuroendocrine function.

Further substantiation of the interaction between psychological disease and the onset of galactorrhea-amenorrhea is presented in women who underwent intensive psychometric and neuroendocrine evaluation prior to the use of the dopamine against 2-Br-alpha-ergocryptine (CB-154). Normalization of a previously distorted psychometric test profile in each woman was accompanied by a profound decline in prolactin and an unexpected alteration in the peripheral concentrations of norepinephrine and dopamine-beta-hydroxylase. Cesation of galactorrhea and resumption of menses were observed in each instance.

Adult↗
PubMed1976

Multifactorial regulation of prolactin secretion.

The hypothalamus exerts an inhibitory influence on prolactin release from the anterior pituitary. Whether or not peptide hypothalamic prolactin-regulating factors, analogous to those for other pituitary hormones, exist, remains to be confirmed. There is evidence that catecholamines and indolamines directly affect prolactin release. This concept may explain the pathogenesis of galactorrhoea-amenorrhoea and other endocrine diseases produced by hypothalamic-pituitary disorders.

Catecholamines↗