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L Katznelson

Publications and source records attributed to L Katznelson.

18 recordsLinked to original sources
PubMed2000

Treatment of acromegaly with the growth hormone-receptor antagonist pegvisomant.

BACKGROUND: Patients with acromegaly are currently treated with surgery, radiation therapy, and drugs to reduce hypersecretion of growth hormone, but the treatments may be ineffective and have adverse effects. Pegvisomant is a genetically engineered growth hormone-receptor antagonist that blocks the action of growth hormone. METHODS: We conducted a 12-week, randomized, double-blind study of three daily doses of pegvisomant (10 mg, 15 mg, and 20 mg) and placebo, given subcutaneously, in 112 patients with acromegaly. RESULTS: The mean (+/-SD) serum concentration of insulin-like growth factor I (IGF-I) decreased from base line by 4.0+/-16.8 percent in the placebo group, 26.7+/-27.9 percent in the group that received 10 mg of pegvisomant per day, 50.1+/-26.7 percent in the group that received 15 mg of pegvisomant per day, and 62.5+/-21.3 percent in the group that received 20 mg of pegvisomant per day (P<0.001 for the comparison of each pegvisomant group with placebo), and the concentrations became normal in 10 percent, 54 percent, 81 percent, and 89 percent of patients, respectively (P<0.001 for each comparison with placebo). Among patients treated with 15 mg or 20 mg of pegvisomant per day, there were significant decreases in ring size, soft-tissue swelling, the degree of excessive perspiration, and fatigue. The score fortotal symptoms and signs of acromegaly decreased significantly in all groups receiving pegvisomant (P< or =0.05). The incidence of adverse effects was similar in all groups. CONCLUSIONS: On the basis of these preliminary results, treatment of patients who have acromegaly with a growth hormone-receptor antagonist results in a reduction in serum IGF-I concentrations and in clinical improvement.

Acromegaly↗
PubMed1999

Long-term mortality after transsphenoidal surgery for Cushing disease.

BACKGROUND: Untreated Cushing disease historically has a high mortality rate, but the long-term survival of patients with Cushing disease after transsphenoidal surgery has not been reported. OBJECTIVE: To determine long-term mortality rate in patients who are treated for Cushing disease with current management techniques. DESIGN: Retrospective case series. SETTING: Tertiary care center. PATIENTS: 161 patients (32 men and 129 women; mean age, 38 years) who were treated for Cushing disease between 1978 and 1996. INTERVENTION: Transsphenoidal adenomectomy and as-needed adjunctive therapy. MEASUREMENT: Record review with follow-up interview. RESULTS: The cure rate for patients with microadenomas who had no previous therapy was 90% (123 of 137). No perioperative deaths occurred (0 of 193 procedures [95% CI, 0.0% to 1.9%]). Follow-up data (mean, 8.7 years) were obtained for 99% of patients (159 of 161). Six patients died. The 5- and 10-year survival rates were 99% (CI, 97% to 100%) and 93% (CI, 88% to 99%), respectively. Survival was similar to that seen in an age- and sex-matched sample that was based on U.S. population data (standardized mortality ratio, 0.98 [CI, 0.44 to 2.2]; P > 0.2). CONCLUSION: Survival of patients treated for Cushing disease with current management techniques between 1978 and 1996 was better than the poor survival historically associated with this disorder.

Adenoma↗
PubMed1999

Medical therapy for gonadotroph and thyrotroph tumors.

Gonadotroph adenomas, a common type of pituitary tumor, are not associated with syndromes of hormonal hypersecretion and thus present as pituitary macroadenomas with mass effects, or as incidentally discovered pituitary masses. When indicated, primary therapy is neurosurgery, but there may be a limited role for medical therapy in patients with residual disease. Thyrotroph adenomas are rare neoplasms that present with hyperthyroidism and local mass effects. Medical therapy may be effective in controlling tumor growth and in achieving euthyroidism, when surgery or radiation, or both, do not control the tumor.

Adenoma↗
PubMed1998

Therapeutic role of androgens in the treatment of osteoporosis in men.

There has been much recent interest in the relationship between androgens and bone mineralization in men. Increases in serum androgens during puberty allow for skeletal maturation and the attainment of peak bone mass, and the persistence of normal testosterone secretion during adulthood is important for the maintenance of bone density. Testosterone deficiency is associated with heightened bone turnover and is a major risk factor for osteoporosis in men. The administration of testosterone to androgen-deficient men leads to an increase in bone mass, particularly in the trabecular bone compartment, and a reduction in levels of surrogate markers of bone turnover, suggesting that androgens have a dampening effect on bone remodelling. In addition, the administration of androgens to eugonadal men with idiopathic osteoporosis, with resulting supraphysiological testosterone concentrations, may lead to increases in bone mineral density. The risk of osteopenia due to androgen deficiency and the benefits of testosterone substitution therapy or supraphysiological administration on bone will be reviewed.

Adult↗
PubMed1998

Long-term mortality after transsphenoidal surgery and adjunctive therapy for acromegaly.

To analyze the long term outcome after multimodality therapy for acromegaly, a retrospective review was performed on 162 patients who underwent transsphenoidal surgery at Massachusetts General Hospital between 1978 and 1996. The surgical cure rate for microadenomas was 91%, that for macroadenomas was 48%, and it was 57% overall. The surgical cure rate was significantly dependent on tumor size, but was not dependent on age or sex. An improvement in the surgical cure rate was noted over the course of the review, from 45% before 1987 to 73% since 1991. Long term follow-up was obtained in 99% of U.S. residents (149 of 151), with a mean follow-up period of 7.8 yr. Adjuvant radiation and/or pharmacological therapy was given to 61 patients. Of the entire group, 83% (124 of 149) were in biochemical remission as determined by normalization of serum insulin-like growth factor I levels or by GH suppression after oral glucose tolerance testing at last contact or at death. The recurrence rate was 6% at 10 yr and 10% at 15 yr after surgery in those patients who initially met the criteria for surgical cure. The 10-yr survival rate was 88%, and there were 12 deaths at postoperative intervals of 2-12 yr, with the most common cause of death being cardiovascular disease. A Cox proportional hazards model showed that patient-years with persistent disease carried a 3.5-fold [95% confidence interval (CI), 1.0-12; P = 0.02] relative mortality risk compared to those patient-years in remission. A Poisson person-years regression analysis showed no significant difference in survival between those 86 patients cured at operation and an age- and sex-matched sample from the U.S. population [standardized mortality ratio (SMR), 0.84; 95% CI, 0.3-2.2; P = 0.35]. A similar analysis on the entire group of 149 patients showed no significant difference in survival from that in a control sample (SMR, 1.16; 95% CI, 0.66-2.0; P = 0.3). Mortality risk for patient-years with persistent active disease after unsuccessful treatment vs. that in the U.S. population sample remained increased (SMR, 1.8; 95% CI, 0.9-3.6; P = .05). This analysis suggests that the decreased survival previously reported to be associated with acromegaly can be normalized by successful surgical and adjunctive therapy.

Acromegaly↗
PubMed1998

Effects of androgen administration on the growth hormone-insulin-like growth factor I axis in men with acquired immunodeficiency syndrome wasting.

It is unknown whether hypogonadism contributes to decreased insulin-like growth factor I (IGF-I) production and/or how testosterone administration may effect the GH-IGF-I axis in human immunodeficiency virus (HIV)-infected men with the acquired immunodeficiency syndrome (AIDS) wasting syndrome (AWS). In this study, we investigate the GH-IGF-I axis in men with the AWS and determine the effects of testosterone on GH secretory dynamics, pulse characteristics determined from overnight frequent sampling, arginine stimulation, and total and free IGF-I levels. Baseline GH-IGF-I parameters in hypogonadal men with AWS (n=51) were compared before testosterone administration (300 mg, im, every 3 weeks vs. placebo for 6 months) with cross-sectional data obtained in two age-matched control groups: eugonadal men with AIDS wasting (n=10) and healthy age-matched normal men (n=15). The changes in GH-IGF-I parameters were then compared prospectively in testosterone- and placebo-treated patients. Mean overnight GH levels [1.8+/-0.3 and 2.4+/-0.3 vs. 0.90+/-0.1 microg/L (P=0.04 and P=0.003 vs. healthy controls)] and pulse frequency [0.35+/-0.06 and 0.37+/-0.02 vs. 0.22+/-0.03 pulses/h (P=0.06 and P=0.002 vs. healthy controls)] were comparably elevated in the eugonadal and hypogonadal HIV-positive groups, respectively, compared to those in the healthy control group. No significant differences in pulse amplitude, interpulse interval, or maximal GH stimulation to arginine administration (0.5 g/kg, i.v.) were seen between either the eugonadal and hypogonadal HIV-positive or healthy control patients. In contrast, IGF-I levels were comparably decreased in both HIV-positive groups compared to the healthy control group [143+/-16 and 165+/-14 vs. 216+/-14 microg/L (P=0.004 and P=0.02 vs. healthy controls)]. At baseline, before treatment with testosterone, overnight GH levels were inversely correlated with IGF-I (r=-0.42; P=0.003), percent ideal body weight (r=-0.36; P=0.012), albumin (r=-0.37; P=0.012), and fat mass (r=-0.52; P=0.0002), whereas IGF-I levels correlated with free testosterone (r=0.35; P=0.011) and caloric intake (r=0.32; P= 0.023) in the hypogonadal HIV-positive men. In a stepwise regression model, albumin (P=0.003) and testosterone (P=0.011) were the only significant predictors of GH [mean GH (microg/L)=-1.82 x albumin (g/dL) + 0.003 x total testosterone (microg/L) + 6.5], accounting for 49% of the variation in GH. Mean overnight GH levels decreased significantly in the testosterone-treated patients compared to those in the placebo-treated hypogonadal patients (0.9+/-0.3 vs. 0.2+/-0.4 microg/L; P=0.020). In contrast, no differences in IGF-I or free IGF-I were observed in response to testosterone administration. The decrement in mean overnight GH in response to testosterone treatment was inversely associated with increased fat-free mass (r=-0.49; P= 0.024), which was the only significant variable in a stepwise regression model for change in GH [change in mean GH (microg/L)=-0.197 x kg fat-free mass - 0.53] and accounted for 27% of the variation in the change in GH. In this study, we demonstrate increased basal GH secretion and pulse frequency in association with reduced IGF-I concentrations, consistent with GH resistance, among both hypogonadal and eugonadal men with AIDS wasting. Testosterone administration decreases GH in hypogonadal men with AIDS wasting. The change in GH is best predicted by and is inversely related to the magnitude of the change in lean body mass in response to testosterone administration. These data demonstrate that among hypogonadal men with the AWS, testosterone administration has a significant effect on the GH axis.

Adult↗
PubMed1998

Prolactin pulsatile characteristics in postmenopausal women.

Pulsatile PRL secretion undergoes diurnal variation, with maximal PRL release in the evening during sleep in both women and men. However, the impact of the menopause on PRL pulsatile dynamics are largely unknown. To characterize diurnal PRL pulsatile secretion in postmenopausal women, we performed frequent venous sampling over 24 h every 10 min for serum PRL in 7 postmenopausal women (age, 56 +/- 4 yr) and in 2 control groups, 8 men (age, 25 +/- 8 yr) and 22 cycling women (age, 28 +/- 5 yr), at 3 phases of the menstrual cycle. Standard TRH tests (200 microg, i.v.) were administered at 0900 h after completion of the 24-h sampling, and PRL levels were then obtained at 0, 10, 20, 30, and 60 min in all subjects. PRL pulse characteristics were similar between the postmenopausal women and men. Mean serum PRL levels and PRL pulse frequency were significantly higher in the cycling women than in either postmenopausal women or men over 24 h and during either the day or night periods. Mean serum PRL levels and pulse frequency were significantly higher during the night compared to those during the day in all groups. Pulse amplitude was higher during the night vs. the day in all groups and was highest in the cycling women. PRL responses to TRH administration were greatest in cycling women. These data demonstrate that PRL pulse dynamics are significantly different between postmenopausal women and cycling women, and endogenous estrogen levels may have an important role in this difference. Pulsatile PRL secretion is similar between postmenopausal women and men, suggesting that estrogen levels modulate PRL dynamics across genders.

Adult↗
PubMed1998

Biochemical assessment of Cushing's disease in patients with corticotroph macroadenomas.

The majority of cases of Cushing's disease are due to an underlying pituitary corticotroph microadenoma (< or = 10 mm). Corticotroph macroadenomas (> 10 mm) are a less common cause of Cushing's disease, and little is known about specific clinical and biochemical findings in such patients. To define further the clinical characteristics of patients with corticotroph macroadenomas, we performed a retrospective review of Cushing's disease due to macroadenomas seen at Massachusetts General Hospital between 1979 and 1995. Of 531 patients identified with a diagnostic code of Cushing's syndrome, 20 were determined to have Cushing's disease due to a macroadenoma based on radiographic evidence of pituitary adenoma greater than 10 mm and pathological confirmation of a pituitary adenoma. A comparison review of charts of 24 patients with Cushing's disease due to corticotroph microadenomas identified on the basis of radiographic evidence of a normal pituitary gland or a pituitary adenoma 10 mm or less in diameter was also performed. The mean ages of the patients (+/- SD) with macroadenomas and microadenomas were similar (39 +/- 12 and 38 +/- 14 yr, respectively). The baseline median 24-h urine free cortisol (UFC) excretion was 1341 nmol/day (range, 304-69,033 nmol/day) and 877 nmol/day (range, 293-2,558 nmol/day) for macroadenoma and microadenoma patients, respectively (P = 0.058). After the 48-h high dose dexamethasone suppression test, UFC decreased by 77 +/- 19% (mean +/- SD) and 91 +/- 7% in macroadenoma and microadenoma subjects, respectively (P = 0.04). Fifty-six percent of macroadenoma patients and 92% of microadenoma patients had greater than 80% suppression of UFC after high dose dexamethasone administration (P = 0.03). The baseline median 24-h urinary 17-hydroxysteroid (17-OHCS) excretion was 52 mumol/day (range, 25-786 mumol/day) and 44 mumol/day (range, 17-86 mumol/day) for macroadenoma and microadenoma subjects, respectively (P = 0.09). After the standard high dose dexamethasone suppression test, 17-OHCS excretion decreased by 46 +/- 33% and 72 +/- 22% for macroadenoma and microadenoma subjects, respectively (P = 0.02). Fifty-three percent of patients with macroadenomas and 86% of patients with microadenomas had greater than 50% suppression of 17-OHCS after high dose dexamethasone administration (P = 0.02). Baseline plasma ACTH values were above the normal range in 83.3% of macroadenoma patients and in 45% of microadenoma subjects (P = 0.05). Tumors were immunostained with the MIB-1 antibody for Ki-67 to investigate proliferation in the adenomas. There was a trend for a higher Ki-67 labeling index in corticotroph macroadenomas, and seven (44%) macroadenomas vs. three (18%) microadenomas had labeling indexes greater than 3%, but this was not statistically significant. In summary, corticotroph macroadenomas are often associated with less glucocorticoid suppressibility than the more frequently occurring microadenomas. Therefore, the lack of suppression of UFC or 17-OHCS after the administration of high dose dexamethasone in a patient with Cushing's disease does not necessarily imply the presence of ACTH-independent Cushing's syndrome and is more commonly seen in patients with corticotroph macroadenomas than in those with microadenomas. Increased plasma ACTH concentrations are typical of patients with corticotroph macroadenomas and may be a more sensitive indicator of neoplastic corticotrophs than the UFC or 17-OHCS response to standard high dose dexamethasone testing.

17-Hydroxycorticosteroids↗
PubMed1998

Effects of physiological growth hormone (GH) therapy on cognition and quality of life in patients with adult-onset GH deficiency.

GH replacement of adults with acquired GH deficiency (GHD) results in body composition changes including increases in lean mass and bone mineral density. However, the effects of long-term GH therapy on cognitive function are largely unknown, and there are conflicting data regarding quality of life. We performed a randomized, double-blind, placebo-controlled study of GH replacement in adults with GHD and measured cognition and sense of well-being using standardized psychometric tests before and after therapy. Forty men (median age 51 yr, range 24-64 yr) with a history of pituitary disease were randomized to GH therapy (starting dose, 10 +/- 0.3 micrograms/kg per day: mean treatment dose, 4 +/- 2 micrograms/kg per day) vs. placebo for 18 months, and GH doses were adjusted according to serum insulin growth factor-I levels. At baseline, the patients displayed a full-scale intelligence quotient (IQ) score nearly 1 SD above the normal mean. Mean scores on all cognitive tests fell within normal limits, and on many tests, fell above the mean. On tests of verbal learning and delayed visual memory, mean test scores fell below the mean (although within normal limits), suggestive of a relative compromise in the area of memory performance. Following 18 months of GH replacement therapy, there were no significant changes in cognitive function or quality of life. We conclude that acquired GHD in adult men is not associated with significant alterations in cognitive function as assessed by standardized tests, and chronic low-dose GH replacement therapy does not result in significant beneficial effects on cognitive function or quality of life. Although previous studies have suggested that GH replacement in adults with acquired GHD may improve quality of life, our data do not support the use of physiological GH replacement in GHD men for this indication.

Adult↗
PubMed1998

Using quantitative CT to assess adipose distribution in adult men with acquired hypogonadism.

OBJECTIVE: Quantitative CT is a powerful tool that may be used to assess distribution of adipose and lean mass and bone mineral density in specific anatomic compartments. Testosterone deficiency (hypogonadism) is increasingly recognized in adult men and is associated with osteoporosis, diminished strength, and an increase in cardiovascular risk. We used quantitative CT to determine whether hypogonadism is associated with fat redistribution and altered bone density. SUBJECTS AND METHODS: Quantitative CT was performed at the level of the L4 vertebra in 26 men with adult onset testosterone deficiency and 17 eugonadal men of similar body mass index and age. Adipose area in the subcutaneous, visceral, and skeletal muscle areas was determined and trabecular bone density was measured. Values between the groups were compared using t tests. RESULTS: The ages of the hypogonadal and eugonadal men were 52 +/- 14 years and 51 +/- 8 years (p value not significant), respectively. Subcutaneous fat area was higher in the testosterone-deficient men than in the control subjects (270 +/- 101 cm2 versus 202 +/- 111 cm2; p = .046). Muscle fat area was higher in the hypogonadal men (6 +/- 3 cm2 versus 2 +/- 1 cm2; p = .001). Measurements of visceral fat were similar for both groups. Trabecular bone density was lower in the hypogonadal than in the eugonadal men (112 +/- 38 mg K2HPO4/dl versus 148 +/- 34 mg K2HPO4/dl, respectively; p = .003). CONCLUSION: Our findings indicate that testosterone deficiency is associated with a decrease in bone density and a redistribution of fat. Quantitative CT is a sensitive method that may be useful in determining alterations in regional adipose deposition in hypogonadal men and in evaluating the benefit of interventional therapy such as testosterone replacement.

Adipose Tissue↗
PubMed1997

Prolactinomas.

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Amenorrhea↗
PubMed1996

Assessment of growth hormone (GH) secretion in men with adult-onset GH deficiency compared with that in normal men--a clinical research center study.

It is not known how patients who acquire GH deficiency (GHD) in adulthood differ in measures of GH secretion from normal adults. To characterize measures of GH secretion in such patients compared to those in normal subjects, we studied 23 men (median age, 51 yr; range, 32-62 yr) with adult-onset pituitary disease, defined as GH-deficient based on having no detectable GH response to two pharmacological agents, and 17 normal men. Patients less than 50 yr old received insulin (0.1 U/kg, i.v.) and clonidine (0.15 mg, orally), whereas those 50 yr of age or older as well as normal controls received arginine (30 g, i.v.) and clonidine. Patients were compared to normal men by investigating GH sampling every 10 min for 24 h and serum levels of insulin-like growth factor I (IGF-I), IGF-binding protein 2 (IGFBP-2), IGFBP-3, and GH-binding protein. Frequent venous sampling of GH was analyzed in terms of mean 24-h levels, pooled 24-h GH, mean levels over the 12 h between 2000-0800 h (mean overnight GH level), and pulse analysis (pulses per 24 h and pulse amplitude) by the Pulsar computer program. Although there were significant differences between the two groups for almost all measures of GH secretion, overlap between the groups was always present. GH levels measured using a highly sensitive chemiluminescence assay on 24-h pools derived from frequent sampling displayed the least overlap between the two groups, as only 2 of 17 normal controls overlapped with the GHD patients. The pooled 24-h GH level using this technique was significantly lower in patients with GHD than in controls (0.117 +/- 0.021 vs. 0.861 +/- 0.098 micrograms/L; P < 0.0001). In the analysis of frequent GH sampling using a standard immunoradiometric assay, mean overnight GH levels provided the best separation between the two groups, as all 23 patients had values of 0.6 microgram/L or less, and 13 of 17 normal controls had values greater than 0.6 microgram/L. The mean overnight GH level in patients was 0.6 +/- 0.0 microgram/L compared to 1.0 +/- 0.1 microgram/L in controls (P < 0.0001). The mean 24-h GH level in patients was 0.5 +/- 0.0 microgram/L compared to 0.8 +/- 0.1 microgram/L in normal controls (P < 0.0001). GH pulse frequency and pulse amplitude were also reduced in patients with GHD compared to those in normal controls [1.7 +/- 0.5 vs. 5.1 +/- 0.5 pulses/24 h (P < 0.0001) and 0.6 +/- 0.1 vs. 2.8 +/- 0.4 microgram/L (P < 0.0001), respectively]. The mean serum IGF-I level was significantly lower in patients with GHD than in normal controls (106.7 +/- 8.0 vs. 218.7 +/- 16.7 microgram/L; P < 0.0001). Three of 23 patients overlapped with control values. Mean serum levels of IGFBP-3 and the serum IGF-I/IGFBP-2 ratio were also significantly lower in patients than in controls, but values overlapped substantially. We conclude that overlap occurs on measures of GH secretion between normal men and men identified as GH deficient despite a stringent definition of GHD. The best separation was obtained using pooled 24-h GH levels determined by a highly sensitive chemiluminescence assay.

Adult↗
PubMed1996

Loss of lean body and muscle mass correlates with androgen levels in hypogonadal men with acquired immunodeficiency syndrome and wasting.

The acquired immunodeficiency syndrome (AIDS) wasting syndrome (AWS) is a devastating complication of human immunodeficiency virus infection characterized by a disproportionate decrease in lean body mass. The pathogenesis of the AWS is unknown, but recent data suggest that endogenous secretion of the potent anabolic hormone, testosterone; is decreased in 30-50% of men with AIDS. However, it is unknown whether decreased androgen levels are associated with decreased lean body mass and/or functional decreases in muscle strength and aerobic capacity in hypogonadal men with the AWS. In addition, testosterone is known to have stimulatory effects on GH secretion, and the loss of these effects on the GH-insulin-like growth factor I (IGF-I) axis may be an additional mechanism of decreased lean body mass in this population. Twenty hypogonadal subjects (free-testosterone < 12 pg/mL) with weight loss > 10% of preillness weight or absolute weight < 90% ideal body weight (IBW) were enrolled in the study. None of the subjects were receiving Megace. Lean body mass and fat-free mass were determined by potassium-40 isotope analysis (40K) and dual-energy x-ray absorptiometry, respectively, and analyzed with respect to gonadal function by linear regression analysis. Muscle mass was determined by urinary creatinine excretion, and exercise functional capacity was assessed by a 6-min walk test, a sit-to-stand test, and a timed get-up-and-go test. Results also were compared with gonadal function by regression analysis. IGF-I and mean overnight GH levels, determined from frequent sampling (q20 min from 2000-0800 h), were compared with results obtained from age- and sex-matched normal controls. Subjects were 26-58 yr of age (39 +/- 7 yr, mean +/- SD) with a CD4 cell count of 150 +/- 186 cells/mm3. Serum levels of FSH were elevated in 30% of the subjects. Muscle mass was significantly reduced, compared with expected mass for height (23.3 +/- 5.5 vs. 29.3 +/- 1.7 kg, P = 0.0001) and was decreased disproportionately to weight (77% of expected value for muscle mass vs. 93% of expected value for weight). Free-testosterone levels were correlated with total body potassium (R = 0.45, P < 0.05) and muscle mass (R = 0.45, P < 0.05). Total-testosterone levels were correlated with exercise functional capacity (R = 0.64, P = 0.01 for the sit-to-stand test and R = 0.53, P < 0.05 for the 6-min walk test). Mean GH levels were significantly increased (3.03 +/- 1.76 vs. 0.90 +/- 0.37 ng/mL, P < 0.001) and IGF-I levels decreased (167 +/- 66 vs. 225 +/- 69 ng/mL, P < 0.01), compared with age- and sex-matched eugonadal controls. GH levels were inversely correlated with caloric intake (R = -0.60, P = 0.02) and percent fat mass by dual-energy x-ray absorptiometry (R = 0.58, P = 0.02). Six additional hypogonadal subjects receiving Megace for AIDS wasting were analyzed separately. Nutritional status and parameters of body composition were compared in the Megace and non-Megace-treated subjects. No significant differences in caloric intake, lean body mass, fat mass, or muscle mass were demonstrated. These data demonstrate that changes in body composition, including loss of lean body and muscle mass, and deterioration in exercise functional capacity are highly correlated with androgen levels in hypogonadal men with the AWS. Furthermore, our data demonstrate significantly increased GH levels and decreased IGF-I in association with low weight in this population. These data suggest that androgen deficiency combined with classical GH resistance may contribute to the critical loss of lean body and muscle mass in hypogonadal men with the AWS. These data are the first to link muscle and lean body wasting with progressive gonadal dysfunction among the large percentage of men with AIDS wasting who are hypogonadal. This demonstrates the need for additional studies to determine the efficacy of gonadal steroid replacement to increase lean body mass in this population.

Adult↗
PubMed1996

Increase in bone density and lean body mass during testosterone administration in men with acquired hypogonadism.

Acquired hypogonadism is being increasingly recognized in adult men. However, the effects of long term testosterone replacement on bone density and body composition are largely unknown. We investigated 36 adult men with acquired hypogonadism (age, 22-69 yr; median, 58 yr), including 29 men with central hypogonadism and 7 men with primary hypogonadism, and 44 age-matched eugonadal controls. Baseline evaluation included body composition analysis by bioimpedance, determination of site-specific adipose area by dual energy quantitative computed tomography scan (QCT) of the lumbar spine, and measurements of spinal bone mineral density (BMD) using dual energy x-ray absortiometry, spinal trabecular BMD with QCT, and radial BMD with single photon absorptiometry. Percent body fat was significantly greater in the hypogonadal men compared to eugonadal men (mean +/- SEM, 26.4 +/- 1.1% vs. 19.2 +/- 0.8%; P < 0.01). The mean trabecular BMD determined by QCT for the hypogonadal men was 115 +/- 6 mg K2HPO4/cc. Spinal BMD was significantly lower than that in eugonadal controls (1.006 +/- 0.024 vs. 1.109 +/- 0.028 g/cm2; P = 0.02, respectively). Radial BMD was similar in both groups. Testosterone enanthate therapy was initiated in 29 hypogonadal men at a dose of 100 mg/week, and the subjects were evaluated at 6-month intervals for 18 months. During testosterone therapy, the percent body fat decreased 14 +/- 4% (P < 0.001). There was a 13 +/- 4% decrease in subcutaneous fat (P < 0.01) and a 7 +/- 2% increase in lean muscle mass (P = 0.01) during testosterone therapy. Spinal BMD and trabecular BMD increased by 5 +/- 1% (P < 0.001) and 14 +/- 3% (P < 0.001), respectively. Radial BMD did not change. Serum bone-specific alkaline phosphatase and urinary deoxypyridinoline excretion, markers of bone formation and resorption, respectively, decreased significantly over the 18 months (P = 0.003 and P = 0.04, respectively). We conclude that testosterone therapy given to adult men with acquired hypogonadism decreases sc fat and increases lean muscle mass. In addition, testosterone therapy reduces bone remodeling and increases trabecular bone density. The beneficial effects of androgen administration on body composition and bone density may provide additional indications for testosterone therapy in hypogonadal men.

Adult↗
PubMed1995

Somatostatin receptor subtype gene expression in pituitary adenomas.

Somatostatin (SRIF) exerts its diverse biological effects through a family of membrane receptors. In addition to inhibiting GH secretion, SRIF has antiproliferative effects and has been used clinically in the treatment of pituitary tumors. SRIF receptor (SSTR) expression has recently been identified in pituitary adenomas, and it is unknown whether differential expression of SSTR subtypes predicts clinical responses to SRIF analogs. We therefore determined which SSTR subtype messenger RNAs (mRNAs) are expressed in pituitary adenoma phenotypes and in normal human pituitary tissue using reverse transcriptase-polymerase chain reaction and tested whether expression of specific SSTR subtype mRNA is necessary for SRIF inhibition of GH secretion in human somatotroph adenomas in vitro. Expression of SSTR subtypes 1, 2, and 5 mRNA was identified in all pituitary adenoma types and normal pituitary tissue. In contrast, SSTR3 mRNA was detected in only one somatotroph adenoma as well as in control insulinoma tissue, a tissue known to express SSTR3 mRNA, and was not detected in normal pituitary tissue. SSTR4 mRNA was not detected in any human pituitary tissue. To determine whether specific SSTR subtype mRNA expression is required for SRIF inhibition of GH secretion, five somatotroph adenomas were treated with 10(-7) mol/L SRIF in vitro, and significant inhibition of GH release occurred in all adenomas. All five tumors expressed SSTR2 mRNA and SSTR5 mRNA, and three expressed SSTR1 mRNA. The absence of SSTR1 mRNA expression did not affect the ability of SRIF to suppress GH secretion. We conclude that: 1) human pituitary adenomas and normal pituitary express multiple SSTR gene transcripts; 2) SSTR5 mRNA, which has not been reported in other human endocrine tumor types, is expressed in neoplastic and normal pituitary tissue; and 3) SSTR2 mRNA, SSTR5 mRNA, and variable SSTR1 mRNA are expressed in GH-secreting tumors, which are responsive to SRIF in vitro. Further understanding of SSTR gene expression in pituitary adenomas will facilitate our understanding of the pathogenetic mechanisms of tumorigenesis and may provide a rationale for the use of specific SRIF analogs for clinical application.

Adenoma↗
PubMed1992

Imbalanced follicle-stimulating hormone beta-subunit hormone biosynthesis in human pituitary adenomas.

Clinically nonfunctioning pituitary adenomas represent approximately 25% of all pituitary tumors. Recent studies using a number of in vitro techniques show that the majority of such tumors produce gonadotropins. Hypersecretion of uncombined gonadotropin subunits by these tumors has also been identified raising the possibility that gonadotropin biosynthetic alterations may occur in neoplastic pituitary tissue. To determine whether underlying intracellular biosynthetic alterations lead to imbalanced secretion of the gonadotropin subunits by such tumors, we investigated 1) steady state gonadotropin-subunit messenger ribonucleic acid (mRNA) levels in tumor tissue from 49 patients with clinically nonfunctioning adenomas, 2) secretion of gonadotropins in dispersed pituitary tumor cultures, and 3) serum concentrations of gonadotropins and free subunits. Northern blots of RNA extracted from surgically obtained pituitary tumor tissue were hybridized with complementary DNA probes for FSH beta, LH beta, and alpha-subunit, and quantitative analysis was done to compare alpha- and beta-subunit biosynthesis in individual tumors. Of these tumors, 47 contained sufficient RNA for Northern analysis and 77% of these tumors contained one or more of the gonadotropin-subunit mRNAs. Steady state alpha-subunit mRNA was detected in 57% of tumors, FSH beta mRNA in 49%, and LH beta in 1 (2%). We found FSH beta mRNA in excess of alpha-subunit mRNA in one-third of tumors, including 9 tumors where alpha-subunit mRNA was undetectable. In cultured cells, FSH beta was secreted in excess of alpha-subunit in 41% of tumors. For those tumors in which both mRNA and culture data were available, FSH beta mRNA and secreted subunit levels were in excess of alpha-subunit in 64% of tumors. We conclude that clinically nonfunctioning pituitary adenomas frequently synthesize excess FSH beta subunit relative to alpha-subunit. This finding is in contrast to previous data in normal pituitary or placental tissue where alpha-subunit is present in excess of beta-subunits at both the mRNA and protein levels. The free-beta-subunit hypersecretion identified in pituitary adenomas may be due to biosynthetic abnormalities intrinsic to neoplastic gonadotrophs.

Adenoma↗
PubMed1992

Chronic somatostatin analog administration in patients with alpha-subunit-secreting pituitary tumors.

Glycoprotein hormone-producing (GPH) pituitary adenomas represent approximately 25% of all pituitary tumors. Elevated serum levels of intact GPHs or their free alpha- and beta-subunits have been demonstrated in patients with such tumors, and isolated hypersecretion of alpha-subunit has been reported to occur in 7% of patients. Somatostatin has been shown to decrease GPH subunit levels in cultured adenoma cells in vitro, and somatostatin receptors have been identified on the cell membranes of these tumors. We, therefore, investigated the effect of chronic somatostatin analog administration on hormone production and tumor size in six patients with GPH-producing macroadenomas and elevated serum alpha-subunit levels. Patients initially received native somatostatin as an iv 250-micrograms bolus at 0800 h, followed by a constant infusion of 2 mg over 4 h, and serum alpha-subunit concentrations were measured at 30-min intervals after baseline sampling for a total of 9 h. Patients then received a somatostatin analog, octreotide (100 micrograms, twice daily, sc) for 8 weeks. Serum alpha-subunit levels were determined weekly at 30-min intervals before and for 4 h after the 0800 h octreotide dose. Pituitary magnetic resonance imaging scans and visual field testing were assessed before and after the study. During the 4-h somatostatin infusion, four patients had a significant decrease in alpha-subunit levels (P < 0.05). During the 8-week chronic octreotide administration period, two patients had significant decreases in alpha-subunit levels of 34.6% and 26.7% (P = 0.03 and 0.01, respectively). One of these two patients had a small reduction in tumor size. Two patients whose serum alpha-subunit level did not significantly change while receiving octreotide had a reduction in tumor size or definite improvement in visual field abnormalities. Three patients received a maximum octreotide dose of 250 micrograms, three times daily. In one patient, there was a significant decrease in alpha-subunit levels by 45% (P = 0.0001) in association with a marked improvement in visual field abnormalities. In another such patient, continued administration of octreotide to a maximum dose of 250 micrograms, three times daily, was associated with a marked reduction in tumor size. Of the four patients who demonstrated significant decreases in alpha-subunit concentrations during the initial somatostatin infusion, three patients had a significant reduction in alpha-subunit levels while receiving octreotide. One patient who did not have a decrease in alpha-subunit levels during the somatostatin infusion demonstrated a small decrease in tumor size during higher dose octreotide treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenoma↗