Andrew R. Hoffman

Diagnosis and Treatment of Hyperprolactinemia: An Endocrine Society Clinical Practice Guideline

OBJECTIVE The aim was to formulate practice guidelines for the diagnosis and treatment of hyperprolactinemia. PARTICIPANTS The Task Force consisted of Endocrine Society-appointed experts, a methodologist, and a medical writer. EVIDENCE This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. CONSENSUS PROCESS One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of The Endocrine Society, The European Society of Endocrinology, and The Pituitary Society reviewed and commented on preliminary drafts of these guidelines. CONCLUSIONS Practice guidelines are presented for diagnosis and treatment of patients with elevated prolactin levels. These include evidence-based approaches to assessing the cause of hyperprolactinemia, treating drug-induced hyperprolactinemia, and managing prolactinomas in nonpregnant and pregnant subjects. Indications and side effects of therapeutic agents for treating prolactinomas are also presented.

Induction of Puberty in Men by Long-Term Pulsatile Administration of Low-Dose Gonadotropin-Releasing Hormone

Puberty is heralded by the appearance of episodic gonadotropin secretion. Men with idiopathic hypogonadotropic hypogonadism have an abnormality in gonadotropin release and do not undergo normal puberty. Since idiopathic hypogonadotropic hypogonadism is thought to represent a disorder of gonadotropin-releasing-hormone (GnRH) secretion, we used long-term low-dose subcutaneous GnRH, administered in an episodic fashion by a portable infusion pump, in an effort to establish a normal adult pattern of gonadotropin secretion in six men. All subjects noted spontaneous erections, nocturnal emissions, and breast tenderness, which were associated with elevations of serum testosterone levels (77 +/- 13 ng per deciliter [mean +/- S.E.] before therapy vs. 520 +/- 182 ng after one month of treatment; P less than 0.001). Gonadotropin levels rose to normal adult ranges within one week of therapy and to supraphysiologic levels by 14 days. Testis size increased in four patients, and spermatogenesis was achieved in three patients by 43 weeks of therapy. These results suggest that long-term episodic GnRH administration can reverse idiopathic hypogonadotropic hypogonadism.

Long-Term Safety of Recombinant Human Growth Hormone in Children

BACKGROUND Between 1985 and 2006, the National Cooperative Growth Study (NCGS) monitored the safety and efficacy of recombinant human growth hormone (rhGH) in 54,996 children. METHODS Enrolled patients were followed until rhGH discontinuation. Investigators submitted adverse event reports for targeted events or those potentially rhGH-related. RESULTS Early concerns about de novo leukemia in patients without risk factors have not been substantiated--three observed vs. 5.6 expected in age-matched general population based on years at risk [standard incidence ratio (SIR), 0.54; 95% confidence interval (CI), 0.11-1.58]. De novo malignancies (intracranial and extracranial) were not significantly increased in patients without risk factors (29 confirmed vs. 26 expected; SIR, 1.12; 95% CI, 0.75-1.61). Second neoplasms occurred in 49 patients, of whom 37 had irradiation for their initial tumors (including five of 16 retinoblastoma patients, three of whom had bilateral retinoblastoma) consistent with an increased risk with rhGH. Thirty-three patients developed type 1 diabetes mellitus (DM) (37 expected; SIR, 0.90; 95% CI, 0.62-1.26). Type 2 DM and nonspecified DM were reported in 20 and eight patients, respectively. Two deaths were reported in patients with Prader-Willi syndrome and five deaths from aortic dissection in patients with Turner syndrome. In patients with organic GH deficiency and idiopathic panhypopituitarism, 11 events of acute adrenal insufficiency occurred, including four deaths, consistent with a reported increased risk for adrenal insufficiency in hypopituitary patients with or without rhGH treatment. CONCLUSION After more than 20 yr, leukemia, a major safety issue initially believed associated with GH, has not been confirmed, but other signals, including risk of second malignancies in patients previously treated with irradiation, have been detected or confirmed through the NCGS. These data further clarify the events associated with rhGH and, although confirming a favorable overall safety profile, they also highlight specific populations at potential risk.

Regulation of telomerase by alternate splicing of human telomerase reverse transcriptase (hTERT) in normal and neoplastic ovary, endometrium and myometrium

Telomerase extends telomeric repeats at the ends of linear chromosomes, thereby prolonging the replicative capacity of cells. To investigate possible regulatory mechanisms of telomerase, we measured telomerase enzyme activity, human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) mRNA in normal and neoplastic ovary, endometrium and myometrium. Telomerase activity was detected in most malignancies and in normal endometrium but not in myometrial leiomyoma, normal myometrium or normal ovary. hTR was expressed in all tissue samples. hTERT mRNA was expressed in many tissue samples, and no tissue sample exhibited telomerase activity without expressing hTERT mRNA. However, the presence of hTR and hTERT mRNA was not sufficient for telomerase activity. Alternate splicing of hTERT produced mRNAs lacking critical reverse transcriptase (RT) motifs in both normal and neoplastic tissues. Only tissues expressing hTERT containing complete A and B RT motifs demonstrated telomerase activity. Finally, several normal ovarian tissues and myometrial leiomyomas lacked telomerase activity despite expressing hTR and hTERT containing complete A and B RT motifs. This was not seen in ovarian and myometrial malignancies, where the expression of hTR and hTERT containing complete A and B RT motifs was sufficient for telomerase activity. We conclude that in ovarian and uterine tissues, the presence of a functional telomerase complex is regulated at multiple levels, including hTERT transcription and alternative splicing of hTERT transcripts. The lack of telomerase activity in several normal but not malignant tissues expressing hTR and hTERT containing complete A and B RT motifs suggests that there are further mechanisms for suppressing telomerase activity downstream of hTERT transcription and mRNA splicing, and these mechanisms have been lost during neoplastic transformation. Int. J. Cancer 85:330–335, 2000.©2000 Wiley‐Liss, Inc.

CTCF Regulates Allelic Expression of Igf2 by Orchestrating a Promoter-Polycomb Repressive Complex 2 Intrachromosomal Loop

ABSTRACT CTCF is a zinc finger DNA-binding protein that regulates the epigenetic states of numerous target genes. Using allelic regulation of mouse insulin-like growth factor II (Igf2) as a model, we demonstrate that CTCF binds to the unmethylated maternal allele of the imprinting control region (ICR) in the Igf2/H19 imprinting domain and forms a long-range intrachromosomal loop to interact with the three clustered Igf2 promoters. Polycomb repressive complex 2 is recruited through the interaction of CTCF with Suz12, leading to allele-specific methylation at lysine 27 of histone H3 (H3-K27) and to suppression of the maternal Igf2 promoters. Targeted mutation or deletion of the maternal ICR abolishes this chromatin loop, decreases allelic H3-K27 methylation, and causes loss of Igf2 imprinting. RNA interference knockdown of Suz12 also leads to reactivation of the maternal Igf2 allele and biallelic Igf2 expression. CTCF and Suz12 are coprecipitated from nuclear extracts with antibodies specific for either protein, and they interact with each other in a two-hybrid system. These findings offer insight into general epigenetic mechanisms by which CTCF governs gene expression by orchestrating chromatin loop structures and by serving as a DNA-binding protein scaffold to recruit and bind polycomb repressive complexes.

Nocturnal Arrhythmias Across a Spectrum of Obstructive and Central Sleep-Disordered Breathing in Older Men: Outcomes of Sleep Disorders in Older Men (MrOS Sleep) Study

BACKGROUND Rates of cardiac arrhythmias increase with age and may be associated with clinically significant morbidity. We studied the association between sleep-disordered breathing (SDB) with nocturnal atrial fibrillation or flutter (AF) and complex ventricular ectopy (CVE) in older men. METHODS A total of 2911 participants in the Outcomes of Sleep Disorders in Older Men Study underwent unattended polysomnography. Nocturnal AF and CVE were ascertained by electrocardiogram-specific analysis of the polysomnographic data. Exposures were (1) SDB defined by respiratory disturbance index (RDI) quartile (a major index including all apneas and hypopneas), and ancillary definitions incorporating (2) obstructive events, obstructive sleep apnea (OSA; Obstructive Apnea Hypopnea Index quartile), or (3) central events, central sleep apnea (CSA; Central Apnea Index category), and (4) hypoxia (percentage of sleep time with <90% arterial oxygen percent saturation). Multivariable logistic regression analyses were performed. RESULTS An increasing RDI quartile was associated with increased odds of AF and CVE (P values for trend, .01 and <.001, respectively). The highest RDI quartile was associated with increased odds of AF (odds ratio [OR], 2.15; 95% confidence interval [CI], 1.19-3.89) and CVE (OR, 1.43; 95% CI, 1.12-1.82) compared with the lowest quartile. An increasing OSA quartile was significantly associated with increasing CVE (P value for trend, .01) but not AF. Central sleep apnea was more strongly associated with AF (OR, 2.69; 95% CI, 1.61-4.47) than CVE (OR, 1.27; 95% CI, 0.97-1.66). Hypoxia level was associated with CVE (P value for trend, <.001); those in the highest hypoxia category had an increased odds of CVE (OR, 1.62; 95% CI, 1.23-2.14) compared with the lowest quartile. CONCLUSIONS In this large cohort of older men, increasing severity of SDB was associated with a progressive increase in odds of AF and CVE. When SDB was characterized according to central or obstructive subtypes, CVE was associated most strongly with OSA and hypoxia, whereas AF was most strongly associated with CSA, suggesting that different sleep-related stresses may contribute to atrial and ventricular arrhythmogenesis in older men.

The Effects of Serum Testosterone, Estradiol, and Sex Hormone Binding Globulin Levels on Fracture Risk in Older Men

CONTEXT The relationship between sex steroids and fracture is poorly understood. OBJECTIVE The objective of the study was to examine associations between nonvertebral fracture risk and bioavailable estradiol (bioE2), bioavailable testosterone (bioT), and SHBG. DESIGN This was a case-cohort study. SETTING The Osteoporotic Fractures in Men Study (MrOS) was conducted in a prospective U.S. cohort in 5995 community-dwelling men 65 yr old or older. PARTICIPANTS Participants included a subcohort of 1436 randomly chosen white men plus all 446 minorities and all those with incident hip and other nonvertebral fractures. MAIN OUTCOME MEASURES Baseline testosterone and estradiol were measured by mass spectrometry (MS) and SHBG by RIA. RESULTS Men with the lowest bioE2 (<11.4 pg/ml) or highest SHBG (>59.1 nm) had greater risk of all nonvertebral fractures [adjusted hazard ratio (HR) [95% confidence interval]: 1.5 (1.2-1.9) and 1.4 (1.1-21.8), respectively]. Men with the lowest bioT (<163.5 ng/dl) had no increased fracture risk after adjustment for bioE2 [adjusted HR 1.16 (0.90-1.49)]. A significant interaction between SHBG and bioT (P = 0.03) resulted in men with low bioT and high SHBG having higher fracture risk [HR 2.1 (1.4-3.2)]. Men with low bioE2, low bioT, and high SHBG were at highest risk [HR 3.4 (2.2-5.3)]. CONCLUSIONS Older men with low bioE2 or high SHBG levels are at increased risk of nonvertebral fracture. When SHBG levels are high, men with low bioT levels have higher risk. The strongest association occurred when all measures were considered in combination.

Systematic Review: The Effects of Growth Hormone on Athletic Performance

The use of human growth hormone to improve athletic performance has recently received worldwide attention. This practice, often called sports doping, is banned by most professional sports leagues and associations, including the International Olympic Committee, Major League Baseball, and the National Football League (13). However, a wide range of athletes, including those from baseball (46), cycling (7, 8), and track and field (5, 9), have been implicated in or have confessed to illicit growth hormone use. The Mitchell report (10) recently identified 89 Major League Baseball players who allegedly used performance-enhancing drugs, and some of these players have subsequently admitted to using growth hormone (11, 12). Part of the attraction of using growth hormone as a performance enhancer has been that its use is difficult to detect. The World Anti-Doping Agency, whose formation stemmed from the widely publicized doping scandal of the 1998 Tour de France (13), first used a blood test to detect exogenous growth hormone during the 2004 Olympic Games in Athens. However, according to the World Anti-Doping Agency, there have been no test-confirmed positive cases for growth hormone doping in professional or Olympic athletes (14), probably because of the limited availability and implementation of this test. Although growth hormone is reportedly used to enhance athletic performance and has been called the most anabolic substance known (15), its efficacy for this purpose is not well established. Some have suggested that growth hormone is a wonder drug (16) that results in ripped muscle (17) and provides stamina-increasing properties (18). Exogenous growth hormone therapy in growth hormonedeficient adults (that is, those with growth hormone deficiency due to hypothalamic or pituitary defects) results in increased lean mass and decreased fat mass (19), and comparable body composition changes are seen in healthy elderly adults who receive growth hormone (20). Some experts, however, have suggested that the strength-enhancing properties of growth hormone among healthy adults have been exaggerated (15). Serious side effects, including diabetes, hepatitis, and acute renal failure, may occur in athletes using high-dose growth hormone (21). Furthermore, the use of growth hormone for athletic enhancement is not approved by the U.S. Food and Drug Administration, and the distribution of growth hormone for this purpose is illegal in the United States (22). We performed a systematic review of randomized, controlled trials to determine the effects of growth hormone therapy on athletic performance in healthy, physically fit, young adults. Our primary aim was to evaluate the effects of growth hormone on body composition, strength, basal metabolism, and exercise capacity. In addition, we sought to synthesize the evidence on adverse events associated with growth hormone in the healthy young and assess the quality of the published literature. Methods Literature Searches In consultation with 2 research librarians, we developed individual search strategies to identify potentially relevant studies from the MEDLINE, EMBASE, SPORTDiscus, and Cochrane Collaboration databases. We sought English-language reports indexed through 11 October 2007 with keywords including growth hormone and randomized, controlled trial (Appendix Table 1). We searched bibliographies of retrieved articles for additional studies. Appendix Table 1. Search Strategy Study Selection We sought randomized, controlled trials, including crossover trials, that compared growth hormone therapy with no growth hormone therapy. We included studies that 1) evaluated at least 5 participants, 2) enrolled only community-dwelling participants, 3) assessed participants with a mean or median age between 13 and 45 years, and 4) provided data on at least 1 clinical outcome of interest. We excluded studies that 1) focused solely on evaluating growth hormone secretagogues, 2) explicitly included patients with any comorbid medical condition, or 3) evaluated growth hormone as treatment for a specific illness (for example, adult growth hormone deficiency or fibromyalgia). Data Abstraction One author reviewed the titles and abstracts of articles identified through our search and retrieved potentially relevant studies. An endocrinologist and a physician with training in meta-analytic techniques separately reviewed the retrieved studies and abstracted data independently onto pretested abstraction forms. We resolved abstraction differences by repeated review and consensus. If a study did not present data necessary for analysis or mentioned results but did not present data, we requested additional data from study authors. If data were presented graphically, we used the graph-digitizing program DigitizeIt, version 1.5 (Share It, Braunschweig, Germany), to abstract data from the graph (23). If multiple studies presented findings from the same cohort, we used these data only once in our analysis. We abstracted 4 types of data from each study: participant characteristics (for example, age, sex, body mass index, baseline maximum oxygen uptake [VO2max]), study interventions (for example, dose, route, frequency, and duration of growth hormone therapy), study quality (for example, quality of randomization and blinding) (24, 25), and clinical outcomes. We included studies that provided data on at least 1 of the following clinical outcomes: body composition (for example, body weight, lean body mass, fat mass), strength (for example, biceps or quadriceps strength), basal metabolism (for example, resting energy expenditure, basal metabolic rate, heart rate, respiratory exchange ratio, or respiratory quotient), exercise capacity (for example, exercising lactate levels, exercising respiratory exchange ratio or respiratory quotient, maximum inspiratory pressure, bicycling speed, and VO2max), or adverse events. Because the terms lean body mass and fat-free mass are typically used interchangeably in the literature, we report fat-free mass and lean body mass data as a single category of lean body mass. Similarly, we report resting energy expenditure and basal metabolic rate as a single category of basal metabolic rate. Quantitative Data Synthesis To describe key study characteristics, we computed mean values weighted by the number of participants in the trial. To evaluate the effects of growth hormone on body composition and strength, we computed a change score for each clinical outcome for both the treatment and control groups as the value of the outcome at trial end minus the value of the outcome at trial start. We used these change scores to calculate the weighted mean difference and standard mean difference (26) effect sizes. The weighted mean difference is reported in the same units as the clinical outcome of interest, thereby facilitating clinical interpretation. Because our outcomes were similar for both methods, we present only the outcomes from the weighted mean difference method. For studies that did not report the variance of an outcome at trial end minus the value at trial start, we calculated it as the sum of the trial-start and trial-end variances minus twice the covariance (20, 27). Because trial-start data were not available for most of the studies reporting basal metabolic outcomes, we compared trial-end results between treatment and control groups for these outcomes. We combined studies by using random-effects models (2628) because of potential interstudy heterogeneity. The considerable variability in exercise protocols used in the included studies reporting exercise capacity outcomes made pooling these results inappropriate. Instead, we provide a narrative, qualitative assessment of exercise capacity outcomes and report their associated published P values. The variability in reporting adverse events among included studies also made a quantitative meta-analysis of these outcomes inappropriate. Instead, we calculated the proportions of adverse events among participants who received and did not receive growth hormone in studies that reported or evaluated for each adverse event. We performed sensitivity analyses and assessed interstudy heterogeneity to evaluate the robustness of our results. We removed each study individually to evaluate that studys effect on the summary estimates. We assessed publication bias by constructing funnel plots and calculated the number of unpublished studies required to statistically significantly change our results (28). We assessed heterogeneity among study results for each of the summary effects by calculating the Q statistic (and associated P value) and I 2 statistic (26, 2830). We evaluated heterogeneity through predetermined subgroup analysis that stratified studies by duration of treatment. We performed analyses by using Stata software, version 9.1 (Stata, College Station, Texas); SPSS, version 15.0 (SPSS, Chicago); and Comprehensive Meta-Analysis, version 2 (Biostat, Englewood, New Jersey). We considered P values less than 0.05 (2-tailed) to indicate statistically significant differences. Role of the Funding Source The authors were supported in part or fully by the Agency for Healthcare Research and Quality, Santa Clara Valley Medical Center, the U.S. Department of Veteran Affairs, Stanford University Medical Center, Stanford University, Genentech, the National Science Foundation, and the Evidence-Based Medicine Center of Excellence of Pfizer. These funding sources had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; the preparation, review, or approval of the manuscript; or the decision to submit the manuscript for publication. Results The Figure summarizes the results of our literature searches. We reviewed 7599 titles from the MEDLINE, EMBASE, SPORTDiscus, and the Cochrane Collaboration databases. From our search, we reviewed 252 abstracts in detail and retrieved 56 articles for full-text evaluation.

Optimized clinical performance of growth hormone with an expanded genetic code

The ribosomal incorporation of nonnative amino acids into polypeptides in living cells provides the opportunity to endow therapeutic proteins with unique pharmacological properties. We report here the first clinical study of a biosynthetic protein produced using an expanded genetic code. Incorporation of p-acetylphenylalanine (pAcF) at distinct locations in human growth hormone (hGH) allowed site-specific conjugation with polyethylene glycol (PEG) to produce homogeneous hGH variants. A mono-PEGylated mutant hGH modified at residue 35 demonstrated favorable pharmacodynamic properties in GH-deficient rats. Clinical studies in GH-deficient adults demonstrated efficacy and safety comparable to native human growth hormone therapy but with increased potency and reduced injection frequency. This example illustrates the utility of nonnative amino acids to optimize protein therapeutics in an analogous fashion to the use of medicinal chemistry to optimize conventional natural products, low molecular weight drugs, and peptides.

Bone mass and strength in older men with type 2 diabetes: The Osteoporotic Fractures in Men Study

The effects of type 2 diabetes mellitus (T2DM) on bone volumetric density, bone geometry, and estimates of bone strength are not well established. We used peripheral quantitative computed tomography (pQCT) to compare tibial and radial bone volumetric density (vBMD, mg/cm3), total (ToA, mm2) and cortical (CoA, mm2) bone area and estimates of bone compressive and bending strength in a subset (n = 1171) of men (≥65 years of age) who participated in the multisite Osteoporotic Fractures in Men (MrOS) study. Analysis of covariance–adjusted bone data for clinic site, age, and limb length (model 1) and further adjusted for body weight (model 2) were used to compare data between participants with (n = 190) and without (n = 981) T2DM. At both the distal tibia and radius, patients with T2DM had greater bone vBMD (+2% to +4%, model 1, p < .05) and a smaller bone area (ToA −1% to −4%, model 2, p < .05). The higher vBMD compensated for lower bone area, resulting in no differences in estimated compressive bone strength at the distal trabecular bone regions. At the mostly cortical bone midshaft sites of the radius and tibia, men with T2DM had lower ToA (−1% to −3%, p < .05), resulting in lower bone bending strength at both sites after adjusting for body weight (−2% to −5%, p < .05) despite the lack of difference in cortical vBMD at these sites. These data demonstrate that older men with T2DM have bone strength that is low relative to body weight at the cortical‐rich midshaft of the radius despite no difference in cortical vBMD.