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Biomedical subjects

Z Hochberg

Publications and source records attributed to Z Hochberg.

At least 145 records · Page 8Linked to original sources
PubMed1985

Calcitriol-resistant rickets with alopecia.

Four children of two kindred had alopecia associated with severe rickets, resistant to treatment, and caused by defective cytoplasmic and nuclear receptors for the active vitamin D metabolite calcitriol (1,25-dihydroxyvitamin D3). Scalp biopsy specimen revealed a normal number and light microscopic features of the hair and hair follicles. Calcitriol-resistant rickets should be added to the list of inherited disorders of hair growth, and the association of rickets with alopecia needs to be considered in the differential diagnosis of hair loss.

Alopecia↗
PubMed1984

Caffeine stimulates growth hormone secretion by cultured rat pituitary cells.

To study the effect of caffeine on growth hormone secretion a culture system of dispersed rat anterior pituitary cells was employed. The cells were incubated overnight in medium 199 containing 10(-5) to 10(-1) M caffeine. The medium was then collected and assayed for rat growth hormone content. A dose dependent stimulatory effect of caffeine on growth hormone secretion into the culture medium was observed. It is concluded that caffeine, like other xanthine phosphodiesterase inhibitors stimulates growth hormone secretion by a direct effect on pituitary cells.

Animals↗
PubMed1984

1,25-Dihydroxyvitamin D resistance, rickets, and alopecia.

Two unrelated kindreds with four affected children having 1,25-dihydroxyvitamin D resistance, rickets, and alopecia are described. The children exhibited early onset of severe rickets with hypocalcemia, hypophosphatemia, elevated serum alkaline phosphatase levels, and secondary hyperparathyroidism. Radiography showed diffuse demineralization and classic changes of rickets. All affected children had total-body alopecia. Serum levels of 1,25-dihydroxyvitamin D3 were elevated and rose to extremely high values during treatment, with no apparent change in the mineral disorder. However, secondary hyperparathyroidism and hypophosphatemia did remit during treatment despite persistently low calcium levels. Skin biopsy was performed in the parents and affected children in one kindred. Analysis of 1,25-dihydroxyvitamin D3 receptors in cultured fibroblasts indicated apparent normal receptors in the parents and undetectable receptors in both affected children. After long periods of treatment with vitamin D metabolites and mineral replacement, healing took place in the older child in each kindred. These data suggest that the healing occurred spontaneously as the children reached seven to nine years of age rather than as a result of the treatment. The biochemical lesion in these children appeared to be a genetically transmitted defect in the 1,25-dihydroxyvitamin D3 receptor. The mechanisms by which healing was initiated and maintained remain to be elucidated.

Alopecia↗
PubMed1984

The modulation of placental lactogen secretion by calcium: studies with cultured human term trophoblast.

Previous reports have documented the negative regulatory effect of calcium ion on the secretion of human placental lactogen by the placenta. Human term trophoblasts were dispersed from term placenta and maintained in monolayer cell culture. Incubation of the cultured trophoblast with EGTA produced a dose-dependent stimulation of placental lactogen secretion. The calcium ionophore A23187 inhibited hormone secretion. This inhibitory effect was eliminated by the addition of the calcium-calmodulin complex inhibitor trifluoperazine. It is concluded that calcium exerts a negative regulatory effect on the secretion of placental lactogen by a mechanism which requires the action of the calcium-calmodulin complex.

Calcimycin↗
PubMed1984

Glomerulosa failure in congenital adrenocortical unresponsiveness to ACTH.

We report two children of a family with congenital adrenocortical unresponsiveness to ACTH. Repeated stimulation of the adrenal by Synthetic 1-24 ACTH (Synacthen) failed to increase cortisol secretion, but produced significant rises of serum aldosterone. This was, however, associated with increased plasma renin activity. Only when the renin-angiotensin effect was eliminated, by a converting enzyme blocker, did Synacthen fail to affect serum aldosterone. These data support the view that glucocorticoid deficiency in this disorder results from unresponsiveness to ACTH and that development of the zona glomerulosa and normal aldosterone secretion is achieved by action of the renin-angiotensin system.

Adrenal Cortex↗
PubMed1984

Plasma and urine osmolality in full-term and pre-term infants.

The purpose of the present study was to determine the normal relationship of urine and plasma osmolality in pre-term and full-term infants. Twenty-nine full-term and 35 pre-term babies were studied during the first week of life. Random simultaneous urine and plasma samples were measured for osmolality. Statistical analysis defined the normal relationship of plasma to urine osmolality. This suggests an osmotic threshold of 282 mOsm/kg and 291 mOsm/kg for full-term and pre-term babies, respectively. These values are different from the 285-290 mOsm/kg of adolescents and adults. The nomograms provided may serve as a useful aid in the bedside diagnosis of dysfunctional secretion of vasopressin.

Humans↗
PubMed1984

Salt loss in congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency.

Nine patients with 11 beta-hydroxylase deficiency had 13 episodes of gastroenteritis requiring hospital admission and fluid administration. Eight episodes were accompanied by hyponatraemia and salt loss. The salt losing patients were treated with excessive glucocorticoid and those with normal serum sodium concentrations were treated with inadequate glucocorticoid. Excessive glucocorticoid suppressed deoxycorticosteroid secretion, resulting in salt loss.

Adrenal Hyperplasia, Congenital↗
PubMed1984

Leucine-induced hypoglycemia in a family: effect of diphenylhydantoin, oxprenolol, and diazoxide.

The present report describes a mother and 2 children with leucine-induced hypoglycemia (LIH). Hypoglycemic episodes following high-protein meals first appeared at age 4-7 months. Leucine-stimulation tests triggered marked hyperinsulinism and hypoglycemia in the children and a milder but abnormal response in the mother. To evaluate the therapeutic effects and to study the mechanism of hyperinsulinism in LIH, the leucine test was repeated under treatment with diphenylhydantoin, oxprenolol (a beta-blocker), and diazoxide. Diazoxide abolished hyperinsulinism; diphenylhydantoin did not affect the response to leucine; and oxprenolol, tested in the mother only, increased hyperinsulinism and hypoglycemia. Our results indicate that LIH is an autosomal dominant disorder; LIH may persist into adulthood with milder clinical symptoms and chemical response to leucine; diazoxide is the treatment of choice in LIH. Considering the effects of the three agents on stimulated release of insulin, it is concluded that leucine triggers hyperinsulinism by a mechanism different from that of glucose and beta-adrenergic receptors.

Adult↗
PubMed1984

Salt loss in hypertensive form of congenital adrenal hyperplasia (11-beta-hydroxylase deficiency).

Studies in patients with congenital adrenal hyperplasia due to 11-hydroxylase deficiency (11-OHD) suggest a common defect in the adrenal zona fasciculate and zona glomerulosa. The hypertension in untreated 11-OHD patients is considered to be secondary to the accumulation of deoxycorticosterone as a consequence of inadequate 11-beta-hydroxylation in the biosynthesis of aldosterone, and is alleviated by glucocorticoid suppression. To investigate whether deoxycorticosterone suppression in these patients resulted in loss of salt, 11 patients with 11-OHD aged 4-26 yr were studied. Patients were evaluated during dexamethasone suppression (0.6 mg/m for 2 weeks) while receiving a normal diet and a low salt diet (10 meq Na/24 h). There was no significant change in serum electrolytes, cortisol, 11-deoxycortisol, and DOC during these two dietary regimens. PRA in the recumbent and upright positions on both diets was significantly higher in the patients than in normal subjects. Plasma or urinary aldosterone levels were significantly lower in the 11-OHD patients than in the normal controls. Moderate salt loss occurred during the low salt diet. It is concluded that sodium retention is incomplete in glucocorticoid-treated 11-OHD patients. Partial sodium retention is maintained by increased PRA and a subnormal aldosterone response. 11-OHD patients should be carefully monitored during acute disease states and, when electrolyte imbalance is suspected, treatment with mineralocorticoid should be considered.

Adolescent↗
PubMed1984

1,25-dihydroxyvitamin D resistance, rickets, and alopecia: analysis of receptors and bioresponse in cultured fibroblasts from patients and parents.

To investigate further the cellular defects of vitamin D-dependent rickets type II with alopecia, we studied 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptors and the response to 1,25-(OH)2D3 in cultured skin fibroblasts from rachitic patients. Our studies included cells from four affected patients from three kindreds and their parents and cells from five normal subjects. We measured total 1,25-(OH)2D3 receptor binding in cell extracts and the capacity of 1,25-(OH)2D3 to induce the enzyme 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase) as a marker of functional response. In normal fibroblasts, the 1,25-(OH)2D3 maximal binding capacity was 52 +/- 5 fmol/100 micrograms DNA (mean +/- SE), and the apparent dissociation constant (Kd) was 0.05 +/- 0.01 nM. The maximal induced 24-hydroxylase activity after 1,25-(OH)2D3 treatment was 11.5 +/- 1 fmol/10(6) cells X 30 min, and the dose of 1,25-(OH)2D3 that achieved half-maximal induction was 2.3 +/- 0.3 nM. Fibroblasts from all four rachitic patients had the same defect: no measurable 1,25-(OH)2D3 receptor binding and no detectable response above basal activity even after high doses of 1,25-(OH)2D3. Cells from all parents except one had normal 1,25-(OH)2D3 binding characteristics and normal 24-hydroxylase bioresponse to 1,25-(OH)2D3. One parent despite a normal phenotype had only half the normal level of binding sites and only half the normal bioresponse. In summary, the cultured fibroblasts from four affected children representing three different kindreds with 1,25-(OH)2D3 resistance failed to exhibit detectable 1,25-(OH)2D3 receptors. We postulate that this biochemical defect produced both the inability to respond to 1,25-(OH)2D3 in vitro and the 1,25-(OH)2D3 resistance in vivo. The obligate heterozygotic parents were normal, except for one who had both half the normal number of receptors and half the normal response to 1,25-(OH)2D3. The data confirm the critical role of the receptor in 1,25-(OH)2D3 action and the close coupling of receptor content and functional responsiveness.

Alopecia↗
PubMed1984

Effects of theophylline on urinary excretion of cyclic AMP, calcium, and phosphorus in normal subjects.

The present study was designed to examine the effects of acute theophylline administration on urinary excretion of cyclic adenosine monophosphate (cAMP), calcium, and phosphorus in normal subjects. The results demonstrated that at therapeutic doses (5 mg i.v./kg body weight) theophylline exerted a distinct biologic effect on renal tubular activity in 5 normal subjects: an increase in nephrogenous cAMP accompanied by a rise in phosphate and calcium urinary excretion. Beyond the clinical implications, the data suggest that theophylline, in contrast to parathyroid hormone, may be acting via cAMP to exert both its phosphaturic and calciuric effect on renal tubules.

Adult↗
PubMed1984

Parathyroid hormone infusion test in children and adolescents.

10 children with short stature were infused with parathyroid hormone (PTH). The results were compared to those obtained from a study of 28 normal adult volunteers. As expected, the children had higher basal serum phosphorus levels than the adults. PTH administration increased urinary excretion of cyclic AMP, sodium, potassium, bicarbonate, phosphate clearance, and reabsorption of calcium. The responses of the children were indistinguishable from those of the adults. Infusion of PTH to 3 children with hypoparathyroidism produced exaggerated cyclic AMP, phosphate, calcium, potassium, and bicarbonate responses. When given to a patient with pseudohypoparathyroidism, it did not increase urinary excretion of cyclic AMP and potassium or phosphate clearance, but did induce normal sodium and bicarbonate excretion. We conclude that the values obtained from normal adults are applicable to children and are useful in the evaluation of hypocalcemia in childhood.

Adolescent↗
PubMed1983

Growth enhancement induced by prolonged L-dopa administration in rats.

To follow growth of rats, in which growth hormone secretion has been chronically stimulated, L-Dopa (5 mg/kg) was injected subcutaneously twice daily for 70 days to growing rats. A control group, matched for sex and sibship, pair fed with the treatment group was given saline injections. At 10-day intervals, the rats were weighed and measured. At 90 days of age the rats were ether anesthesized, bled for growth hormone determination, and internal viscera weighed. Weight gain and length in the L-Dopa-treated group was found to be significantly greater. A mean weight gain of 6% and 12% in the male and female rats, respectively, and a mean length gain of 5% in both male and female rats was observed at 90 days of age. The thymus, thyroid, adrenals, uterus, and gonads all tended to be heavier in the L-Dopa-treated group. Significantly heavier kidneys were found in the L-Dopa group. Serum growth hormone was found to be 8.44 +/- 1.4(SE) ng/ml in the L-Dopa group and 4.6 +/- 0.9 ng/ml in the control group. It is concluded that the continuous administration of L-Dopa produces an increase of circulating serum growth hormone levels, and this in turn enhances growth.

Animals↗
PubMed1983

Normal osmotic threshold for vasopressin release in the hyponatremia of hypothyroidism.

To explore a possible downward setting of the hypothalamic osmoreceptors in the hyponatremia of hypothyroidism, 4 adolescent patients with hypothyroidism were studied. Plasma and urine osmolality were measured on random paired simultaneous samples, and following a water load. The osmotic threshold was determined by the isovolemic infusion of hypertonic NaCl, and compared to the osmotic threshold of 6 healthy subjects. Random paired urine and plasma osmolality revealed inappropriately high urine osmolality for the given plasma osmolality. A water load produced a normal dilution of urine. Osmotic threshold was found at plasma osmolality of 286-287 mosm/kg, compared to 286.7 +/- 1.0 in 6 normal individuals. It is concluded that none of the known types of the syndrome of inappropriate ADH secretion could account for the hyponatremia in the hypothyroid patients, and that patients with hypothyroidism have normal osmoreceptors as measured by the osmotic threshold test.

Adolescent↗
PubMed1983

Insulin regulates placental lactogen and estradiol secretion by cultured human term trophoblast.

We have described a human term trophoblast cell culture system which synthesizes hormones de novo from their precursors. In the present report we utilized this monolayer system to show that insulin produced a dose-dependent stimulation of hPL secretion, with a significant effect at 10(-10) M insulin. At 10(-9) M concentration, insulin also inhibited estradiol secretion by the cultured trophoblast. We conclude that insulin regulates secretion of estradiol and placental lactogen by cultured human term trophoblast.

Cells, Cultured↗
PubMed1983

Prolactin binding by testes of unilaterally cryptorchid rats: the effect of hCG, testosterone, prolactin and orchiopexy.

The effect of unilateral cryptorchidism on prolactin binding to the testes was studied in the rat. Cryptorchidism was rendered surgically for 3 weeks and 3, 6 and 9 weeks later prolactin binding was measured in testicular homogenates. Prolactin binding to the cryptorchid testes decreased significantly at 3 weeks with a further decrease at 6 and 9 weeks. Binding by the contralateral testes decreased at 3 weeks and increased at 6 and 9 weeks. To examine the possible mechanism of these changes one group of rats was treated for 5 weeks with testosterone and another with hCG. Testosterone treatment resulted in a significant fall in prolactin binding to normal, cryptorchid and contralateral testes. hCG also produced a slight but significant reduction in prolactin binding. To study the effect of surgical relocation of the testes into the scrotum, orchiopexy was performed in another group of rats. Orchiopexy increased prolactin binding only if performed 3 weeks after cryptorchidism. At 6 and 9 weeks after cryptorchidism orchiopexy did not increase prolactin binding. Treatment of cryptorchid rats with prolactin for 5 weeks induced an increase in prolactin binding to control, cryptorchid and contralateral testes. It is concluded that testicular atrophy follows upon placement of a testis within the peritoneal cavity. This atrophy lowers the total amount of prolactin binding and increases binding to the contralateral testes. Intratesticular concentration of testosterone may play a major role in the decrease of prolactin binding. Orchiopexy improves prolactin binding only if performed before 6 weeks of age. Administration of prolactin augments prolactin binding to the testes, irrespective of their location.

Animals↗