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D Kleinberg

Publications and source records attributed to D Kleinberg.

17 recordsLinked to original sources
PubMed2005

Consensus statement: medical management of acromegaly.

In November 2003, the Pituitary Society and the European Neuroendocrine Association sponsored a consensus workshop in Seville to address challenging issues in the medical management of acromegaly. Participants comprised 70 endocrinologists and neurosurgeons with international expertise in managing patients with acromegaly. All participants participated in the workshop proceedings, and the final document written by the scientific committee reflects the consensus opinion of the interactive deliberations. The meeting was supported by an unrestricted educational grant from Ipsen. No pharmaceutical representatives participated in the program planning or in the scientific deliberations.

Acromegaly↗
PubMed2002

Effects of a growth hormone receptor antagonist on bone markers in acromegaly.

OBJECTIVE: Excess GH secretion, as occurs in acromegaly, is associated with abnormalities in bone turnover markers and bone mineral density (BMD). GH administration in GH deficient patients causes an increase in bone turnover. IGF-I mediates many of the metabolic actions of GH, although GH may have direct effects upon bone. In patients with acromegaly who are treated with a GH receptor antagonist, selective blockade of the GH receptor results in a decrease in circulating IGF-I levels in the majority of cases. We hypothesized that, in acromegaly, antagonism of GH receptors would result in a decrease in serum markers of bone turnover, including serum procollagen I carboxy-terminal propeptide (PICP), osteocalcin and N-telopeptide (NTx). DESIGN AND SUBJECTS: Twenty-seven patients with acromegaly were enrolled as part of a multicentre 12-week trial of a GH receptor antagonist and were randomized to placebo (n = 7) or 10, 15 or 20 mg of pegvisomant (n = 20). MEASUREMENTS: Serum markers of bone turnover were determined at baseline and 12 weeks. RESULTS: Baseline bone turnover markers were above the upper limit of normal in 23%, 19% and 32% of subjects for osteocalcin, PICP and NTx, respectively. During the 12-week placebo-controlled period, there were significant decreases in serum markers of bone formation, osteocalcin (-2.2 +/- 0.44 vs. placebo +0.01 +/- 0.39 nmol/l, P = 0.009) and PICP (-23.6 +/- 9.6 vs. placebo +18.1 +/- 12.8 micro g/l, P = 0.022) and a serum marker of bone resorption, NTx (-4.4 +/- 1.4, placebo +1.0 +/- 0.3 nm, P = 0.024). CONCLUSIONS: Using a specific GH receptor antagonist, we found that normalization of IGF-I is associated with rapid reductions in markers of both bone formation and resorption, and that these processes remain coupled. These data confirm the highly significant effects of GH and IGF-I in modulating bone turnover. The independent contributions of GH and IGF-I to these effects and the long-term effects on BMD in this population remain to be determined.

Acromegaly↗
PubMed2001

Hypogonadism in patients with acromegaly: data from the multi-centre acromegaly registry pilot study.

OBJECTIVE: Because acromegaly is an uncommon disorder, epidemiological data regarding the demographics of the disease such as the prevalence of hypogonadism have been limited. In order to derive clinical and epidemiological information, including underlying hormonal factors, regarding hypogonadism in patients with acromegaly, we performed a pilot study designed to develop a multi-centre acromegaly patient registry. DESIGN AND MEASUREMENTS: Medical records of patients with acromegaly seen between 1976 and 1996 at three Institutions were reviewed, and data were entered into a database using a secure internet website. Hypogonadism was defined as amenorrhoea in women and testosterone deficiency in men. Subanalysis was performed in patients with microadenomas and women less than 50 years of age, to include women of reproductive age. RESULTS: Information was available on 363 patients, of whom 54% were women. The mean age at diagnosis was 41 +/- 13 years. In subjects less than 50 years of age, hypogonadism was present in 59%. Hyperprolactinaemia was present in 45% and 21% of hypogonadal and eugonadal patients of reproductive age, respectively (P = 0.0003). GH levels were higher in patients with hypogonadism (P = 0.03). In patients < 50 years of age with microadenomas, hypogonadism was present in nine of the 22 (41%) patients, including 55% of the women and 27% of the men (P = ns). Hyperprolactinaemia was present in three of the 10 and four of the 14 of microadenoma patients with hypogonadism and eugonadism, respectively. CONCLUSION: We developed a web-based acromegaly patient registry and used it to show that hypogonadism is a frequent consequence of acromegaly, even in patients with microadenomas, who are not at risk from hypopituitarism due to local mass effects. We also demonstrated that prolactin and GH hypersecretion contribute to the pathogenesis of hypogonadism in acromegaly, and that hypogonadism may occur in microadenoma patients even in the absence of hyperprolactinaemia.

Acromegaly↗
PubMed1998

Current treatment guidelines for acromegaly.

Acromegaly, an indolent disorder of growth hormone (GH) hypersecretion is most typically caused by a somatotroph cell adenoma and may be treated by several modalities. Transsphenoidal surgical resection of micro-adenomas by experienced neurosurgeons results in biochemical normalization (postglucose GH <2 ng/mL, assay-dependent, age- and sex-matched IGF-I levels) in 70% of patients. However, over 65% of GH-secreting adenomas are invasive or macroadenomas, and over 50% of these patients have persistent postoperative GH hypersecretion. Irradiation of adenomas results in attenuation of GH secretion to more than 5 ng/mL in 50% of subjects after 12 yr. However, the percent of parents who normalize IGF-I levels is less certain. Most of these patients develop associated pituitary failure and rarely develop other local adverse effects. About 60% of patients receiving somatostatin analogs achieve normalized IGF-I levels. Efficacy of medical management with somatostatin analogs may be improved by increasing injection frequency, changing delivery modes to depot preparations, and in the future, development of novel SRIF receptor subtype-specific analogs. An integrated approach to acromegaly management based upon relative risks and benefits of the currently available therapeutic modes is presented that allows for a national individualized strategy designed to achieve maximal biochemical control of GH hypersecretion and elevated IGF-I levels.

Acromegaly↗
PubMed1996

Sublingual testosterone replacement improves muscle mass and strength, decreases bone resorption, and increases bone formation markers in hypogonadal men--a clinical research center study.

To study the effects of androgen replacement therapy on muscle mass and strength and bone turnover markers in hypogonadal men, we administered sublingual testosterone (T) cyclodextrin (SLT; 5 mg, three times daily) to 67 hypogonadal men (baseline serum T, < 8.4 nmol/L) recruited from 4 centers in the U.S.: Torrance (n = 34), Durham (n = 12), New York (n = 9), and Salem (n = 12). Subjects who had received prior T therapy were withdrawn from injections for at least 6 weeks and from oral therapy for 4 weeks. Body composition, muscle strength, and serum and urinary bone turnover markers were measured before and after 6 months of SLT. We have shown previously that this regimen for 60 days will maintain adequate serum T levels and restore sexual function. Total body (P = 0.0104) and lean body mass (P = 0.007) increased with SLT treatment in the 34 subjects in whom body composition was assessed. There was no significant change in total body fat or percent fat. The increase in lean body mass was mainly in the legs; the right leg lean mass increased from 8.9 +/- 0.3 kg at 0 months to 9.2 +/- 0.3 kg at 6 months (P = 0.0008). This increase in leg lean mass was associated with increased leg muscle strength, assessed by leg press (0 months, 139.0 +/- 4.0 kg; 6 months, 147.7 +/- 4.2 kg; P = 0.0038). SLT replacement in hypogonadal men led to small, but significant, decreases in serum Ca (P = 0.0029) and the urinary calcium/creatinine ratio (P = 0.0066), which were associated with increases in serum PTH (P = 0.0001). At baseline, the urinary type I collagen-cross linked N-telopeptides/creatinine ratio [75.6 +/- 7.9 nmol bone collagen equivalents (BCE/mmol] was twice the normal adult male mean (41.0 +/- 3.6 nmol BCE/mmol) and was significantly decreased in response to SLT treatment at 6 months (68.2 +/- 7.7 nmol BCE/mmol; P = 0.0304) without significant changes in urinary creatinine. Serum skeletal alkaline phosphatase did not change. In addition, SLT replacement caused significant increases in serum osteocalcin (P = 0.0001) and type I procollagen (P = 0.0012). Bone mineral density did not change during the 6 months of SLT treatment. We conclude that SLT replacement therapy resulted in increases in lean muscle mass and muscle strength. Like estrogen replacement in hypogonadal postmenopausal females, androgen replacement therapy led to decreased bone resorption and urinary calcium excretion. Moreover, androgen replacement therapy may have the additional benefit of increasing bone formation. A longer term study for several years duration would be necessary to demonstrate whether these changes in bone turnover marker levels will result in increased bone mineral density decreased fracture risks, and reduced frailty in hypogonadal men.

Administration, Sublingual↗
PubMed1994

Visual loss in pregnant women with pituitary adenomas.

OBJECTIVE: To investigate the potential risk for developing visual loss during single or multiple pregnancies in women with pituitary adenomas. DESIGN: Cohort study. SETTING: Referral center of a neuro-ophthalmology service. PATIENTS: 65 consecutive women with pituitary adenomas who had not been previously treated with surgery or radiation were monitored during 111 pregnancies. Sixty had increased levels of serum prolactin or growth hormone and 5 did not. MAIN OUTCOME MEASURES: Visual field or acuity loss was compared with the baseline size of the adenoma measured on the coronal view of the computed tomographic or magnetic resonance image. RESULTS: Computed tomography or magnetic resonance imaging showed a definitive tumor (> 0.3 cm, vertical height) in 57 patients, 8 of whom had macroadenomas (> or = 1.1 cm). Visual field loss occurred in 6 of 8 primiparous patients, all with adenomas greater than 1.1 cm (range, 1.2 to 2.5 cm). None of the 57 patients (95% CI, 0% to 6.3%) with a microadenoma or presumed microadenoma of 1 cm or smaller developed visual loss after as many as four full-term pregnancies. CONCLUSIONS: The risk for developing visual loss during single or multiple pregnancies in patients with microadenomas was small. Six of eight pregnant women with macroadenomas, however, developed visual field loss during pregnancy.

Acromegaly↗
PubMed1991

Ovarian control of pituitary hormone secretion in early human pregnancy.

To determine the influence of ovarian relaxin on the secretion of pituitary GH and PRL in vivo, we evaluated circulating serum hormone levels in 17 pregnant patients with functional corpora lutea (group I) and compared them to levels in 10 patients with premature ovarian failure (POF; group II) who became pregnant with egg donation and did not have corpora lutea. Group II patients had exogenous hormonal support. Serum relaxin (RLX), GH, PRL, estradiol (E2), and progesterone levels were measured weekly by RIA from weeks 4-8 of pregnancy. Analysis of variance and covariance were used to determine hormonal relationships. Serum RLX was present in the natural pregnancy group, with a mean of 1.94 micrograms/L over the study period. Serum RLX was undetectable in the POF patients (less than 0.16 micrograms/L). No significant difference in PRL or progesterone levels between the two groups was noted. E2 levels showed an upward trend in both groups with time and were significantly higher in patients of the POF group than in group I women (P = 0.001). GH levels were significantly higher in the natural cycle patients (P = 0.02) despite lower E2 levels. These data provide additional support for the concept that RLX production in early pregnancy originates from the corpus luteum. They suggest that a luteal product, probably RLX, stimulates GH secretion in early pregnancy. This is a previously undescribed role for RLX in pituitary physiology during human pregnancy.

Adult↗
PubMed1989

Growth of prolactinoma despite lowering of serum prolactin by bromocriptine.

Four patients with macroprolactinomas treated with bromocriptine had tumor growth and visual loss despite marked reduction in their serum prolactin levels. Explanations for this dissociation of tumor growth and prolactin measurement might include noncompliance. Patients treated with bromocriptine require periodic examination by computed tomographic scan or magnetic resonance imaging and neuro-ophthalmological evaluation in addition to monitoring of serum prolactin.

Adult↗
PubMed1981

A double-blind comparison of trebenzomine and thioridazine in the treatment of schizophrenia.

Forty inpatient volunteers with diagnoses of schizophrenia were randomly assigned to treatment either with trebenzomine or thioridazine in a double-blind study of clinical antipsychotic efficacy following a 1-week placebo treatment. Psychopathology was rated using the Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impression (CGI). There was a significant difference in therapeutic response to the two drugs in that psychopathology decreased significantly for the thioridazine group, but not for the trebenzomine group. Serum prolactin was elevated during treatment with thioridazine, but not with trebenzomine. Side effects were more frequently reported for the thioridazine group. These results fail to confirm previous reports of clinical antipsychotic efficacy for trebenzomine.

Adolescent↗
PubMed1981

Treatment of advanced Parkinson disease with pergolide.

Pergolide mesylate, a semisynthetic ergoline and a potent, long-acting central dopamine agonist, was tested in 13 patients with advanced Parkinson disease and diurnal oscillations in performance ("wearing-off" or "on-off" phenomena or both) whose response to levodopa had diminished considerably. Among all nine patients who completed the initial clinical trial, pergolide alone (two patients) or combined with levodopa (seven patients) had a marked antiparkinson effect. There was a significant reduction (p less than 0.05) in rigidity, bradykinesia, gait disorder and total Parkinson disease disability score. Pergolide had a marked effect in all the patients with "wearing-off" or "on-off" phenomena or both, resulting in a significant increase (p less than 0.01) in the duration of the time patients were "on." the number of hours in which patients were "on" increased from 3.8 +/- 0.5 (SEM) to 11.4 +/0 ).8 (SEM). The main daily dose of pergolide was 2.4 mg (range, 2 to 5 mg). Ten months later, all nine patients are doing well. Pergolide is an effective drug in patients with advanced Parkinson disease and reduces "on-off" phenomena.

Aged↗
PubMed1981

Lisuride in Parkinson disease: efficacy of lisuride compared to levodopa.

Lisuride hydrogen maleate, a semisynthetic ergoline and potent central dopamine and serotonin agonist, was tested in 10 patients with moderate to marked Parkinson disease whose response to levodopa had diminished. In the group of 10 patients, there was a significant reduction (p less than or equal to 0.05) in bradykinesia, gait disorder, and total Parkinson disease disability score when levodopa was replaced with lisuride. The mean dose of lisuride was 3.6 mg per day. Among the 10 patients, 5 were better on lisuride than on levodopa, and 4 continue on lisuride 1 year later. A decline in efficacy was noted in all four after a mean of 45 months. Adverse effects necessitating discontinuing the drug were mental changes in three patients and nausea in one patient. Lisuride, when used alone, has definite antiparkinsonian activity and is a promising new drug.

Aged↗
PubMed1980

Metoclopramide: antipsychotic efficacy of a drug lacking potency in receptor models.

Metoclopramide is a substituted benzamide derivative, structurally similar to procainamide and sulpiride. In behavioral, biochemical, and neuroendocrine tests it displays classic neuroleptic dopamine (DA) antagonist properties; in contrast to other DA antagonists, it lacks potency in currently used DA receptor models. In clinical studies using low doses or dubious measures, it was considered not to be efficacious as an antipsychotic. We now find that it indeed has a clinical profile similar to known neuroleptics when used in a dose range predicted from animal models. The findings raise questions regarding the validity and universality of several predictive models, as well as hypotheses purporting to explain molecular mechanisms of action of neuroleptic agents. The drug's inactivity in receptor models suggests that an as yet unidentified DA receptor subpopulation may be important as the mediator of many DA dependent neurobiologic phenomena.

Antipsychotic Agents↗
PubMed1977

Dopaminergic agonist properties of ephedrine--theoretical implications.

Reports of ephedrine-induced psychoses resembling amphetamine psychosis prompted studies of this classic sympathomimetic agent in systems that indicate central dopaminergic actions. Ephedrine induced dose-related stereotyped behavior in rats. This behavior was antagonized by haloperidol, but not by alpha- or beta-adrenergic blockers. Pretreatment with AMPT, but not reserpine, attenuated the stereotypy induced by ephedrine under one of two sets of conditions. Consistent prolactin suppression in humans was not seen. These findings are discussed in the context of clinical and pharmacologic data regarding other dopamine agonist drugs (the central nervous system stimulants, apomorphine, ET 495). These data suggest the possibility that synergistic noradrenergic and dopaminergic facilitation may be important in the induction of the stimulant psychoses.

Animals↗