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Biomedical subjects

J M Gertner

Publications and source records attributed to J M Gertner.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effects of systemic growth hormone (GH) administration on regional adipose tissue distribution and metabolism in GH-deficient children.

Chronic administration of exogenous GH to GH-deficient children is associated with a redistribution of adipose tissue from an abdominal (android) to a more peripheral (gynoid) distribution. We studied abdominal and gluteal sc adipose tissue from seven GH-deficient children 1) before beginning and 2) after 3 months of therapy with exogenous GH (0.1 mg/kg, sc, three times per week). In abdominal and gluteal adipocytes, we measured lipid content and rates of in vitro lipolysis and lipogenesis in response to insulin and various adrenoreceptor agonists. These results were correlated with measures of statural growth and adipose tissue distribution in each subject. We found that GH therapy was associated with a significant reduction in abdominal adipocyte size (0.68 +/- 0.09 micrograms lipid/cell before therapy vs. 0.49 +/- 0.07 after therapy; P less than 0.05), a significant reduction in overall basal rates of lipogenesis (0.43 +/- 0.06 mumol [14C]acylglyceride synthesized/10(6) cells.2 h before therapy vs. 0.27 +/- 0.09 after therapy), and with variable desensitization of abdominal sc adipose tissue to the antilipolytic effect of insulin. The extent of this decrease in insulin action was significantly correlated with changes in abdominal adipocyte lipid content (r = 0.77; P less than 0.05), and with the changes in the anatomical distribution of fat during the study period (r = 0.97; P less than 0.001), as measured by the relative lipid content per adipocyte at each site. We conclude that the site-specific changes in adipose distribution during GH administration are due in part to anatomical site-specific GH-mediated changes in insulin responsiveness of adipose tissue and that exogenous GH therapy is associated with a decrease in de novo triglyceride synthesis in GH-deficient children.

Adipose Tissue↗
PubMed1989

Growth and final height in classical and nonclassical 21-hydroxylase deficiency.

Final height was evaluated in 47 patients with classical 21-hydroxylase treated since diagnosis, and in 29 patients with nonclassical (NC) 21-hydroxylase deficiency who had never been treated before reaching final adult height. Classical patients achieved final heights consistently below the mean for the general population, and in all but four cases these patients also failed to attain the individual height expectation based on midparental height. Analysis of these results with regard to (1) clinical form (i.e. salt-wasting [SW] or simple virilizing [SV]) and (2) degree of hormonal control (i.e. good or poor) indicates that neither factor seems to affect the height outcome. Final height in NC patients, while significantly greater than for classical patients, was below the general population mean, and individual final heights were also significantly below expectation based on midparental height. In another group of NC patients who were still growing, some of whom were on courses of treatment and some under observation only, height at the time of diagnosis was compared with the most recent height prediction. Reduction of growth potential appeared to be somewhat lessened in the treated group, from which we tentatively suggest that treatment should be considered in NC patients even in the absence of clinical signs of androgenism.

Adolescent↗
PubMed1988

Short-term met-hGH infusion inhibits somatotroph response to growth hormone releasing hormone (1-44).

To determine whether the short-term administration of growth hormone inhibits pituitary responsiveness to h-GHRH we measured the somatotroph response to h-GHRH-44 (0.3 micrograms/kg) stimulation in ten normal subjects from the third to the fifth hour of an infusion of met-hGH (2 micrograms/kg/h) or saline. Insulin, insulin-like growth factors (IGF), somatomedins, free fatty acids (FFA), glycerol, and glucose levels also were assessed during the first 3 hours of infusion. Steady-state GH levels of 5 to 20 ng/mL were achieved during met-hGH infusion. No significant changes in IGF, insulin, or glucose levels measured at the beginning and again after three hours of infusion occurred within or between conditions. Infusion of met-hGH was associated with a significantly greater increase in FFA levels (69 +/- 50 mumol/L following saline v 433 +/- 57 mumol/L following three hours of met-hGH infusion (P less than .001)). The somatotroph response to h-GHRH-44 was significantly blunted during met-hGH infusion (incremental area under the GH/time curve decreasing from 1,196 +/- 183 (ng/mL) X min to 380 +/- 139 (ng/mL) X min (P less than .005)). These data demonstrate that this blunting can occur following short-term exogenous GH administration and at serum GH levels comparable to those achieved during naturally occurring bursts of GH secretion. They also suggest that acute mediation of GH release must occur, at least in part, at the pituitary somatotroph level and that IGFs and/or insulin may not be the primary inhibitors. This phenomenon may be directly or indirectly due to GH-dependent metabolic factors such as FFA or glycerol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Hypocalciuria in preeclampsia.

We studied 40 women in the third trimester of pregnancy to determine whether alterations in serum calcium levels or in urinary calcium excretion would distinguish patients with preeclampsia from normal pregnant women or women with other forms of gestational hypertension. Our population included 10 normal pregnant women, 5 pregnant women with transient hypertension, 6 with chronic hypertension, 7 with chronic hypertension and superimposed preeclampsia, and 12 with preeclampsia. The serum levels of ionized calcium, phosphate, and 1,25-dihydroxyvitamin D were not different among the various groups. In contrast, the mean (+/- SD) 24-hour urinary calcium excretion in the patients with preeclampsia or hypertension with superimposed preeclampsia was significantly lower (42 +/- 29 and 78 +/- 49 mg) than that in normal pregnant women (313 +/- 140 mg per 24 hours), women with transient hypertension (248 +/- 139 mg per 24 hours), or women with chronic hypertension (223 +/- 41 mg per 24 hours) (P less than 0.0001). The hypocalciuria in the women with preeclampsia was associated with a decreased fractional excretion of calcium. Although the mean creatinine clearance was reduced in the women with preeclampsia, the range of values overlapped with those in the other groups. In contrast, we observed little or no overlap with respect to calcium excretion. We conclude that preeclampsia is associated with hypocalciuria due to increased tubular reabsorption of calcium. Measurement of calcium excretion may be useful in distinguishing preeclampsia from other forms of gestational hypertension.

Adult↗
PubMed1987

Provocative testing for occult medullary carcinoma of the thyroid: findings in seven children with multiple endocrine neoplasia type IIa.

A rise in the serum calcitonin (CT) following provocative testing has facilitated making the diagnosis of occult medullary carcinoma of the thyroid (MCT) or C cell hyperplasia (CCH) in asymptomatic children of kindred with multiple endocrine neoplasia (MEN) type IIa. Findings were reviewed for seven children varying in age from 3 to 16 years screened at our institution between 1976 and 1986. Three had elevated basal calcitonin (S-CT). Six had significant elevation of calcitonin (delta-CT) after stimulation. Total thyroidectomy was performed in all seven. Five had MCT with bilobar involvement in three. CCH was present in all five. Two patients had no gross, microscopic, or immunohistochemical evidence of MCT or CCH. One of three had an elevated S-CT. The other had a significant delta-CT. All patients have normal postoperative S-CT and delta-CT. Our experience indicates the importance of beginning stimulation tests of affected kindred at less than 3 years of age. It appears, however, that neither elevated S-CT or positive delta-CT are perfect predictors of parafollicular cell pathology. Solitary parathyroid enlargement, second thyroid malignancy, and branchial pouch anomalies may occur with MEN IIa. One patient with MCT had a focus of papillary carcinoma. One patient with primary hyperparathyroidism had a solitary enlarged parathyroid adenoma. Additional findings were the presence of nodules of ectopic thymus in close association with the thyroid gland in three patients.

Adolescent↗
PubMed1986

Pregnancy as state of physiologic absorptive hypercalciuria.

An increase in circulating, 1,25-dihydroxyvitamin D level and net intestinal calcium absorption have been previously demonstrated in pregnant women and have been widely regarded as compensatory mechanisms whereby fetal mineral demands are satisfied. The alternate possibility, that these adjustments might anticipate such demands, has not previously been considered. To examine the effects of pregnancy on the intestinal absorption and renal excretion of calcium, oral calcium tolerance tests were performed and urinary calcium excretion was measured in 16 healthy women receiving a moderate calcium intake during and after pregnancy. Circulating 1,25-dihydroxyvitamin D levels and indexes of parathyroid function were also measured. As expected, 1,25-dihydroxyvitamin D levels were significantly (p less than 0.05) elevated throughout pregnancy (94 +/- 11, 118 +/- 9, and 117 +/- 11 pg/ml in the first, second, and third trimesters, respectively, versus 51 +/- 5 pg/ml after delivery). Twenty-four-hour calcium excretion also increased sharply (247 +/- 54, 316 +/- 42, 300 +/- 61 mg versus 91 +/- 18 mg), often to the point of hypercalciuria. Calcium tolerance test results included significant increases in the calciuric and calcemic responses during each trimester, whereas fasting calcium excretion and parathyroid function remained normal. These findings portray normal pregnancy as a state of physiologic absorptive hypercalciuria and call into question the widespread practice of supplementing calcium intake in otherwise well-nourished women during pregnancy.

Adult↗
PubMed1986

Linkage analyses of multiple endocrine neoplasia, type 2 (MEN-2) with 23 classical genetic polymorphisms.

Linkage analyses were performed in a single large family with multiple endocrine neoplasia, type 2 (MEN-2) between 23 classical genetic polymorphisms and MEN-2. We exclude close linkage of the locus for MEN-2 with ABO, ACP1, BF, ESD, Fy, GALT, GLO1, Jk, MNSs, P, PGM1, Rh and TF, as well as absolute linkage with GPT. These results raise to about 6% the proportion of the genome that has been excluded in this one family. Somewhat positive lod scores were obtained for GC (0.92 at theta = 0), GPT (0.73 at theta = 0.1) and HP (1.49 at theta = 0.05); although not statistically significant, these findings suggest regions of the genome that warrant additional study.

Alleles↗
PubMed1986

Suppression of the growth hormone (GH) response to clonidine and GH-releasing hormone by exogenous GH.

GH release in response to clonidine and human GH-releasing hormone-(1-44) (hGHRH-44) was assessed in 11 boys (aged 7-14 yr) with short stature, who had normal GH secretion. The response to these 2 provocative stimuli was repeated after, respectively, 2 and 3 days of treatment with human GH (0.1 U/kg, im). Exogenous GH significantly blunted the response to both clonidine [the mean 2-h integrated serum GH concentration falling from 1050 +/- 350 (+/- SEM) to 749 +/- 297 ng/ml X min; P = 0.03] and hGHRH-44, the 2-h integrated GH concentration falling from 1553 +/- 358 to 547 +/- 202 ng/ml X min; (P = 0.03). Plasma insulin-like growth factor (IGF-II) concentrations did not change after GH administration. In contrast, plasma IGF-I (somatomedin-C) concentrations increased from 97 +/- 16 ng/ml before administration of GH to 142 +/- 32 ng/ml (P = 0.05) after two days and 149 +/- 23 ng/ml (P less than 0.01) after the third treatment day. However, no correlation was found between the changes in response to clonidine or hGHRH-44 and changes in circulating levels of IGF-I. Our data confirm the existence of GH-dependent feedback inhibition of GH release during childhood and suggest that this inhibition operates, at least in part, at the level of the pituitary. While participation of the IGFs/somatomedins in this feedback loop cannot be excluded, the inhibitory effects of exogenous GH do not depend directly on circulating plasma IGF-I or IGF-II levels.

Adolescent↗
PubMed1985

Elevated production rate of 1,25-dihydroxyvitamin D in patients with absorptive hypercalciuria.

Previous studies of 1,25-dihydroxyvitamin D [1,25-(OH)2D] kinetics in normal subjects using the pulse injection technique have led to conflicting results, and only limited data are available concerning 1,25-(OH)2D kinetics in hypercalciuric patients. We developed an infusion equilibrium technique that measures the metabolic clearance and production rates of 1,25-(OH)2D and applied this technique in 13 normal subjects and 9 well characterized patients with absorptive hypercalciuria; all subjects were studied after 10 days on a 400-mg calcium intake. All subjects received a constant infusion of [3H]1,25-(OH)2D3 (20,000 dpm/min). Purified plasma radioactivity reached steady state levels after 15 h, and between 15 and 19 h, serial measurements of purified plasma radioactivity and endogenous 1,25-(OH)2D were made for calculation of metabolic clearance and production rates. In the 13 normal subjects, the MCR values were within a narrow range, with a mean +/- SD value of 37 +/- 6 ml/min, which, when combined with the mean steady state concentration of endogenous 1,25-(OH)2D (42 +/- 6 pg/ml), yielded a mean production rate of 2.2 +/- 0.5 micrograms/day. In the 9 patients with absorptive hypercalciuria, MCR values also were tightly clustered, with a mean of 35 +/- 4 ml/min. However, the mean endogenous steady state 1,25-(OH)2D level was significantly elevated in these patients, such that the calculated mean 1,25-(OH)2D production rate was significantly elevated at 3.4 +/- 0.5 micrograms/day. In 7 of the 9 patients with absorptive hypercalciuria, production rates exceeded the highest values found in the normal subjects. These data demonstrate disordered 1,25-(OH)2D production as opposed to metabolic clearance in the syndrome of absorptive hypercalciuria.

Adult↗
PubMed1985

Exogenous growth hormone levels predict attentional performance: a preliminary report.

The imminent commercial availability of synthetic growth hormone (GH) and the potential for large scale and possibly indiscriminant use mandate a critical examination of possible adverse effects. This double-blind study examined the effects of human GH on attention. Treatment of eight GH-deficient children, aged 8.7 to 14.1 years, was suspended to establish base lines. Injections with GH (0.1 units/kg) and placebo followed in counterbalanced 2-week periods. At the end of each period, GH levels were assayed, and attention was tested. Scores earned under the GH condition did not differ from base line and placebo values. However, patients displaying high levels (14 +/- 2.12 ng/ml) of exogenous GH 12 hours after injection generally surpassed norms and patients with low levels (3.5 +/- 1.12 ng/ml) of GH under all conditions of the experiment. If 12-hour levels in this study are indicative of the fate of GH received during therapy, prolonged use of GH may bring benefits to attention that vary directly with half-life.

Adolescent↗
PubMed1984

Prospective clinical trial of human growth hormone in short children without growth hormone deficiency.

Ten unselected, apparently healthy short children who were capable of normal growth hormone secretion were given human growth hormone (0.1 U/kg 1M thrice weekly) for 6 months to determine whether such treatment might lead to an increase in growth velocity. During treatment, all patients increased their growth rate (from 4.3 +/- 0.3 cm/yr to 7.4 +/- 0.5 cm/yr P less than 0.001). No adverse effects were detected. During the four-day IGF generation test, IGF I and IGF II levels rose significantly from 0.32 +/- 0.04 U/ml to 0.62 +/- 0.13 U/ml and from 279 +/- 36 ng/ml to 434 +/- 49 ng/ml, respectively. However, the growth response was not predicted by either the acute rise in IGF I or that in IGF II. Human growth hormone in standard doses may be capable of inducing accelerated growth in some short children without growth hormone deficiency. Measurements of IGF I and II cannot be used to predict which children will respond.

Blood Glucose↗