bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Hormone Receptor Antagonist Therapy in Acromegalic Patients Resistant to Somatostatin Analogs*
Authors: Herman-Bonert Vivien S. , Zib Kenneth , Scarlett John A. , Melmed Shlomo
Published: January 2014

Transsphenoidal surgical resection is the primary therapy for acromegaly caused by GH secreting pituitary adenomas. Medical therapy for patients not controlled by surgery includes primarily somatostatin analogs and secondarily dopamine agonists, both of which inhibit pituitary growth hormone secretion. A novel GH receptor antagonist (pegvisomant) binds to hepatic GH receptors and inhibits peripheral insulin-like growth factor-1 generation. Six patients resistant to maximal doses of octreotide therapy received pegvisomant—three received placebo or pegvisomant 30 mg or 80 mg weekly for 6 weeks and three received placebo and pegvisomant 10–20 mg/d for 12 weeks. Thereafter, all patients received daily pegvisomant injections of doses determined by titrating IGF-1 levels. Serum total IGF-1 levels were normalized in all six acromegalic patients previously shown to be resistant to somatostatin analogs via a novel mechanism of peripheral GH receptor antagonism. The GH receptor antagonist is a useful treatment for patients harboring GH-secreting tumors who are resistant to octreotide.
Genome Screen for QTLs Contributing to Normal Variation in Bone Mineral Density and Osteoporosis*
Authors: Koller D. L. , Econs M. J. , Morin P. A. , Christian J. C. , Hui S. L. , Parry P. , Curran M. E. , Rodriguez L. A. , Conneally P. M. , Joslyn G. , Peacock M. , Johnston C. C. , Foroud T.
Published: January 2014

A major determinant of the risk for osteoporosis is peak bone mineral density (BMD), which is largely determined by genetic factors. We recently reported linkage of peak BMD in a large sample of healthy sister pairs to chromosome 11q12–13. To identify additional loci underlying normal variations in peak BMD, we conducted an autosomal genome screen in 429 Caucasian sister pairs. Multipoint LOD scores were computed for BMD at four skeletal sites. Chromosomal regions with LOD scores above 1.85 were further pursued in an expanded sample of 595 sister pairs (464 Caucasians and 131 African-Americans).

The highest LOD score attained in the expanded sample was 3.86 at chromosome 1q21–23 with lumbar spine BMD. Chromosome 5q33–35 gave a LOD score of 2.23 with femoral neck BMD. At chromosome 6p11–12, the 464 Caucasian pairs achieved a LOD score of 2.13 with lumbar spine BMD. Markers within the 11q12–13 region continued to support linkage to femoral neck BMD, although the peak LOD score was decreased to 2.16 in the sample of 595 sibling pairs. Our study is the largest genome screen to date for genes underlying variations in peak BMD and represents an important step toward identifying genes contributing to osteoporosis in the general population.
Genome-Wide Scan of Obesity in Finnish Sibpairs Reveals Linkage to Chromosome Xq24*
Authors: Öhman Miina , Oksanen Laura , Kaprio Jaakko , Koskenvuo Markku , Mustajoki Pertti , Rissanen Aila , Salmi Jorma , Kontula Kimmo , Peltonen Leena
Published: January 2014

Obesity is a multifactorial trait with evidence of a genetic component. Obesity is very common in all westernized countries, including Finland, where 10% of the adult population has a body mass index of 32 kg/m2 or more. Here we report results from a three-stage genome-wide scan of obesity in 188 affected subjects (body mass index,≥ 32 kg/m2) from 87 Finnish families. Initially, 374 markers with an average density of 10 centimorgans were genotyped. The strongest evidence for linkage to obesity was detected on chromosome Xq24, with the marker DXS6804 providing a maximum likelihood score (MLS) 3.14 in a model-free 2-point sibpair analysis. Fine-mapping in an extended sample set of 367 affected subjects from 166 families yielded a multipoint MLS of 3.48 over this X-chromosomal region. The Xq24 region contains a plausible candidate gene, serotonin 2C receptor, variants of which have been shown to predispose to obesity and type II diabetes in mice. Another chromosomal region also provided suggestive evidence of linkage, an area on 18q21, flanking the melanocortin-4 receptor, where a 2-point MLS of 2.42 with marker D18S1155 was obtained with a set of 367 affected subjects. In conclusion, our results in this Finnish study sample suggest that a locus on chromosome Xq24 influences the risk of obesity.
Circulating Thyroglobulin Transcytosed by Thyroid Cells Is Complexed with Secretory Components of Its Endocytic Receptor Megalin*
Authors: Marinò Michele , Chiovato Luca , Mitsiades Nicholas , Latrofa Francesco , Andrews David , Tseleni-Balafouta Sophia , Collins A. Bernard , Pinchera Aldo , McCluskey Robert T.
Published: January 2014

After its endocytosis from the colloid, some thyroglobulin (Tg) is transcytosed intact across thyrocytes, accounting in part for its presence in the circulation. We previously showed that megalin (gp330), an endocytic Tg receptor, mediates apical to basolateral Tg transcytosis. Here we investigated whether a portion of megalin remains combined with Tg after its transcytosis, using studies with cultured thyroid cells and in vivo observations.

FRTL-5 cells, a rat thyroid cell line, cultured on filters in dual chambers form tight junctions and exhibit features of polarity, with expression of megalin exclusively on the upper (apical) surface. After the addition of unlabeled Tg to the upper chamber and incubation at 37 C, some Tg was transcytosed intact across FRTL-5 cells into the lower chamber. Two antimegalin ectodomain antibodies precipitated transcytosed Tg in fluids collected from the lower chamber. After the addition of Tg to surface-biotinylated FRTL-5 cells, an anti-Tg antibody and the two antimegalin ectodomain antibodies precipitated high molecular mass biotinylated material in fluids collected from the lower chamber, corresponding to much of the megalin ectodomain, as well as smaller amounts of lower molecular mass material. The results indicate that Tg transcytosed across FRTL-5 cells remains complexed with megalin ectodomain components, which we refer to as megalin secretory components.

In aminotriazole-treated rats, which develop increased megalin-mediated Tg transcytosis, antimegalin antibodies precipitated some of the Tg in the serum. Tg was also precipitated by antimegalin antibodies in sera from patients with Graves’ disease, in which we found increased megalin expression on the apical surface of thyrocytes. In contrast, in thyroidectomized patients with metastatic papillary thyroid carcinoma, in whom Tg is directly secreted by neoplastic thyroid cells into the circulation rather than transcytosed, serum Tg was not precipitated by antimegalin antibodies. The detection of Tg-megalin complexes may help identify the source of serum Tg in patients with thyroid diseases.
Phenotypic Diversity and Testosterone-Induced Normalization of Mutant L712F Androgen Receptor Function in a Kindred with Androgen Insensitivity*
Authors: Holterhus Paul-Martin , Sinnecker Gernot H. G. , Hiort Olaf
Published: January 2014

Molecular causes of phenotypic diversity in androgen insensitivity syndrome, occurring even in the same family, have rarely been identified. We report on a family with four affected individuals, three brothers (B1–3) and their uncle, displaying strikingly different external genitalia: B1, ambiguous; B2, severe micropenis; B3, slight micropenis; and uncle, micropenis and penoscrotal hypospadias. All had been assigned a male gender. We detected the same L712F mutation of the androgen receptor (AR) gene in each subject. Methyltrienolone binding on cultured genital skin fibroblasts of B2 suggested moderate impairment of the ligand-binding domain [maximal binding capacity, 38.2 fmol/mg protein (normal); Kd, 0.21 nmol/L; normal range, 0.03–0.13 nmol/L]. In trans-activation assays, the mutant 712F-AR showed considerable deficiency at low concentrations of testosterone (0.01–0.1 nmol/L) or dihydrotestosterone (0.01 nmol/L). Remarkably, this could be fully neutralized by testosterone concentrations greater than 1.0 nmol/L. Hence, the 712F-AR could switch its function from subnormal to normal within the physiological concentration range of testosterone. This was reflected by an excellent response to testosterone therapy in B1, B2, and the uncle. Taking into account the well documented individual and time-dependent variation in testosterone concentration in early fetal development, our observations clearly illustrate the potential impact of varying ligand concentrations for distinct cases of phenotypic variability in androgen insensitivity syndrome.
Differential Expression of Estrogen Receptor α and β Immunoreactivity in the Human Supraoptic Nucleus in Relation to Sex and Aging*
Authors: Ishunina Tatjana A. , Kruijver Frank P. M. , Balesar Rawien , Swaab Dick F.
Published: January 2014

The dorsolateral supraoptic nucleus (dl-SON) is the main production site of plasma arginine vasopressin (AVP). Plasma AVP levels and the activity of AVP neurons in humans are higher in males than in premenopausal females. On the other hand, an increased activity of AVP neurons becomes prominent in postmenopausal women who have strongly decreased estrogen levels. As estrogens are presumed to inhibit AVP production in a receptor-mediated way, we studied estrogen receptor (ER) α and β immunoreactivity in the dl-SON. Hypothalami of 34 controls were subdivided into 4 groups within a 50-yr boundary (young men, young women, elderly men, and elderly women). The AVP part of the dl-SON of young women contained 50 times more neurons with ERβ nuclear staining than that in young men and 250 times more than that in elderly women. In addition, young women also showed more ERβ cytoplasmic staining than young men and elderly women. In contrast to the ERβ immunoreactivity, no differences were found in the number of ERα-positive neurons in the 4 groups, but the age and sex pattern of ERα staining was basically opposite that of ERβ. Significant correlations between the percentage of ERβ- and ERα-positive and -negative AVP neurons and age were found in women, but not in men. Our data demonstrate for the first time a strong decrease of ERβ and an increase of ERα immunoreactivity in AVP neurons of the dl-SON of postmenopausal women. Both receptor changes are proposed to participate in the activation of the AVP neurons in postmenopausal women.
Recombinant Human Insulin-Like Growth Factor I Treatment for 1 Week Improves Metabolic Control in Type 2 Diabetes by Ameliorating Hepatic and Muscle Insulin Resistance*
Authors: Cusi Kenneth , DeFronzo Ralph
Published: January 2014

The administration of recombinant human insulin-like growth factor I (rhIGF-I) reduces hyperglycemia and insulin requirements in subjects with severe insulin resistance syndromes and in patients with type 2 diabetes mellitus (T2DM). However, the mechanisms responsible for the improved metabolic control are incompletely understood. One proposed mechanism is that rhIGF-I therapy in T2DM may bypass early defects in insulin action (i.e. signal transduction), leading to improved hepatic and/or peripheral insulin sensitivity. To test this hypothesis, we used the euglycemic insulin clamp to measure the response to 7 days of rhIGF-I therapy (80 μg/kg, sc, twice daily) in eight poorly controlled T2DM subjects. rhIGF-I significantly improved fasting (203 ± 12 vs. 134 ± 14 mg/dL; P < 0.01) and day-long (0800–1700 h; 234 ± 11 vs. 153 ± 10 mg/dL; P < 0.01) plasma glucose levels. Basal endogenous glucose production decreased from 3.2 ± 0.2 to 2.7 ± 0.2 mg/kg lean body mass· min (P < 0.03) despite a concomitant decline in the fasting plasma insulin concentration from 13 ± 5 to 5 ± 1 μU/mL (P < 0.01). The decrement in basal endogenous glucose production was closely correlated with the decrement in fasting plasma glucose concentration (r = 0.78; P < 0.01). Whole body insulin-stimulated glucose disposal increased by 27% (from 5.6 ± 0.8 to 7.1 ± 0.8 mg/kg lean body mass·min; P < 0.01), but remained well below that observed in age- and weight-matched healthy subjects. The effects of rhIGF-I on endogenous glucose production and peripheral insulin sensitivity resemble those observed with intensified insulin regimens in T2DM. We conclude that 7 days of sc rhIGF-I improves glucose control by improving hepatic and muscle insulin sensitivity, but it remains markedly abnormal. This indicates that an intrinsic defect(s) responsible for insulin resistance in T2DM cannot be overcome by rhIGF-I treatment.
Carbohydrate-Induced Hypertriglyceridemia: An Insight into the Link between Plasma Insulin and Triglyceride Concentrations*
Authors: McLaughlin T. , Abbasi F. , Lamendola C. , Yeni-Komshian H. , Reaven G.
Published: January 2014

This study was initiated to test the hypothesis that endogenous hypertriglyceridemia results from a defect in the ability of insulin to inhibit the release of very low-density lipoprotein-triglyceride (TG) from the liver. To accomplish this goal, plasma glucose, insulin, free fatty acid (FFA), and TG concentrations were compared in 12 healthy volunteers, in response to diets containing either 40% or 60% of total calories as carbohydrate (CHO). The protein content of the two diets was similar (15% of calories), and the fat content varied inversely with the amount of CHO (45% or 25%). The diets were consumed in random order, and measurements were made of plasma glucose, insulin, FFA, and TG concentrations at the end of each dietary period, fasting, and at hourly intervals following breakfast and lunch. The results indicated that the 60% CHO diet resulted in higher fasting plasma TG concentrations associated with higher day-long plasma insulin and TG concentrations, and lower FFA concentrations. These results do not support the view that hypertriglyceridemia is secondary to a failure of insulin to inhibit hepatic TG secretion.
Insulin Inhibits NFκB and MCP-1 Expression in Human Aortic Endothelial Cells
Authors: Aljada Ahmad , Ghanim Husam , Saadeh Rana , Dandona Paresh
Published: January 2014

In view of our recent demonstration that insulin inhibits the expression of intercellular adhesion molecule-1 (ICAM-1) and the fact that ICAM-1 expression is known to be modulated by nuclear factor-κB (NFκB), we have now investigated whether insulin inhibits intranuclear NFκB binding activity. We have also investigated whether insulin inhibits the pro-inflammatory chemokine, monocyte chemoattractant protein-1 (MCP-1), which attracts leucocytes to the inflamed sites and is also regulated by NFκB. Insulin was incubated with cultured human aortic endothelial cells (HAEC) at 0, 100 and 1000μ U/mL. Intranuclear NFκB binding activity was suppressed by approximately 45% at 100 μU/mL and by 60% at 1000 μU/mL (p< 0.05). MCP-1 mRNA expression was also suppressed by 47% at 100μ U/mL and by 79% at 1000 μU/mL (p < 0.05). We conclude that insulin at physiologically relevant concentrations exerts an inhibitory effect on the cardinal pro-inflammatory transcription factor NFκB and the pro-inflammatory chemokine MCP-1; these effects suggest an anti-inflammatory and potential anti-atherogenic effects of insulin.
Immunotherapy for Medullary Thyroid Carcinoma by Dendritic Cell Vaccination
Authors: Schott Matthias , Seissler Jochen , Lettmann Melanie , Fouxon Vladimir , Scherbaum Werner A. , Feldkamp Joachim
Published: January 2014

Recent studies suggest that immunization with autologeous dendritic cells (DCs) pulsed with tumor antigen result in protective immunity and rejection of established tumors in various human malignancies. The objective of this study was to develop a DC vaccination therapy in patients with metastasized medullary thyroid carcinoma (MTC). Mature DCs were generated from peripheral blood monocytes in the presence of granulocyte macrophage colony-stimulating factor, IL-4, and TNFα. After loading with calcitonin and carcinoembryonic antigen (CEA) peptide, 2–5 × 106 DCs were repeatedly delivered by sc injections.

During follow-up (mean, 13.1 months) all patients developed a strong delayed-type hypersensitivity skin reaction caused by perivascular and epidermal infiltration with CD4+ memory T cells and CD8+ cytotoxic T cells. Clinical responses with a decrease of serum calcitonin and CEA were initially documented in three of seven patients. One of these patients had a complete regression of detectable liver metastases and a significant reduction of pulmonary lesions. T-cell response in this patient revealed a calcitonin- and CEA-specific immunreactivity.

Our data indicate that vaccination with calcitonin and/or CEA peptide-pulsed DC results in the induction of a cellular, antigen-specific immune response in patients with MTC, leading to clinical response in some patients. Our approach may represent the basis for the development of new therapeutic strategies not only in MTC but also in other endocrine malignancies.
Increased Pulsatility, Process Irregularity, and Nocturnal Trough Concentrations of Growth Hormone in Amenorrheic Compared to Eumenorrheic Athletes1
Authors: Waters Debra L. , Qualls Clifford R. , Dorin Richard , Veldhuis Johannes D. , Baumgartner Richard N.
Published: January 2014

Amenorrheic athletes exhibit a spectrum of neuroendocrine disturbances, including alterations in the GH-insulin-like growth factor I (IGF-I) axis. Whether these changes are due to exercise or amenorrhea is incompletely characterized. The present study investigates spontaneous (overnight) and exercise-stimulated GH secretion and associated IGF-binding proteins (IGFBPs) in amenorrheic (AA; n = 5), and eumenorrheic athletes ( n = 5) matched for age, percent body fat (dual energy x-ray absorptiometry), training history, and maximal oxygen consumption. Each volunteer participated in two hospital admissions consisting of a 50-min submaximal exercise bout (70% maximal oxygen consumption) and an 8-h nocturnal sampling period. Deconvolution analysis of serum GH concentration time series revealed increases in the half-life of GH (60%) and the number of secretory bursts (85%) as well as a decrease in their half-duration (50%) and the mass of GH secreted per pulse (300%) in the AA cohort. Time occupancy at elevated trough GH concentrations was significantly increased, and GH pulsatility (approximate entropy) was more irregular in the AA group. During exercise, AA exhibited a reversal of the normal relationship between IGF-I and GH, and a 4- to 5-fold blunting of stimulated peak and integrated GH secretion. Fasting levels of plasma IGF-I, IGFBP-3, and IGFBP-1 appeared to be unaffected by menstrual status. In ensemble, this phenotype of GH release in amenorrheic athletes suggests disrupted neuroregulation of episodic GH secretion, possibly reflecting decreased somatostinergic inhibition basally, and reduced GHRH output in response to exercise compared with eumenorrheic athletes. Accordingly, we postulate that the amenorrheic state, beyond the exercise experience per se, alters the neuroendocrine control of GH output in amenorrheic athletes.
One Year of Insulin-Like Growth Factor I Treatment Does Not Affect Bone Density, Body Composition, or Psychological Measures in Postmenopausal Women1
Authors: Friedlander Anne L. , Butterfield Gail E. , Moynihan Sharon , Grillo Jeanine , Pollack Margaret , Holloway Leah , Friedman Leah , Yesavage Jerome , Matthias Dwight , Lee Scott , Marcus Robert , Hoffman Andrew R.
Published: January 2014

The activity of the hypothalamic-GH-insulin-like growth factor I (hypothalamic-GH-IGF-I) axis declines with age, and some of the catabolic changes of aging have been attributed to the somatopause. The purpose of this investigation was to determine the impact of 1 yr of IGF-I hormone replacement therapy on body composition, bone density, and psychological parameters in healthy, nonobese, postmenopausal women over 60 yr of age. Subjects (n = 16, 70.6 ± 2.0 yr, 71.8 ± 2.8 kg) were randomly assigned to either the self-injection IGF-I (15 μg/kg twice daily) or placebo group and were studied at baseline, at 6 months, and at 1 yr of treatment. There were no significant differences between the IGF-I and placebo groups in any of the measured variables at baseline. Fasting blood IGF-I levels were significantly elevated above baseline values (65.6 ± 11.9 ng/mL) at 6 months (330.0 ± 52.8) and 12 months (297.7 ± 40.8) in the IGF-I treated group but did not change in the placebo subjects. Circulating levels of IGF-binding protein-1 and -3 were unaffected by the IGF-I treatment. Bone mineral density of the forearm, lumbar spine, hip, and whole body [as measured by dual-energy x-ray absorptiometry (DXA)] did not change in either group. Similarly, there was no difference in DXA-measured lean mass, fat mass, or percent body fat throughout the treatment intervention. Muscle strength values (grip, bench press, leg press), blood lipid parameters (cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides), and measures of postmeal glucose disposal were not altered by IGF-I treatment, although postmeal insulin levels were lower in the IGF-I subjects at 12 months. IGF-I did not affect bone turnover markers (osteocalcin and type I collagen N-teleopeptide), but subjects who were taking estrogen had significantly lower turnover markers than subjects who were not on estrogen at baseline, 6 months, and 12 months. Finally, the psychological measures of mood and memory were also not altered by the intervention. Despite the initial intent to recruit additional subjects, the study was discontinued after 16 subjects completed the protocol, because the preliminary analyses above indicated that no changes were occurring in any outcome variables, regardless of treatment regimen. Therefore, we conclude that 1 yr of IGF-I treatment, at a dose sufficient to elevate circulating IGF-I to young normal values, is not an effective means to alter body composition or blood parameters nor improve bone density, strength, mood, or memory in older women.
Effect of Low-Density Lipoprotein Apheresis on Kinetics of Apolipoprotein B in Heterozygous Familial Hypercholesterolemia1
Authors: Maugeais Cyrille , Ouguerram Khadija , Frénais Regis , Maugère Pascale , Charbonnel Bernard , Magot Thierry , Krempf Michel
Published: January 2014

The acute reduction of low-density lipoprotein (LDL) cholesterol obtained by LDL-apheresis allows the role of the high level of circulating LDL on lipoprotein metabolism in heterozygous familial hypercholesterolemia (heterozygous FH) to be addressed. We studied apolipoprotein B (apoB) kinetics in five heterozygous FH patients before and the day after an apheresis treatment using endogenous labeling with [2H3]leucine. Compared with younger control subjects, heterozygous FH patients before apheresis showed a significant decrease in the fractional catabolic rate of LDL (0.24 ± 0.08 vs. 0.65 ± 0.22 day−1; P < 0.01), and LDL production was increased in heterozygous FH patients (18.9 ± 7.0 vs. 9.9 ± 4.2 mg/kg·day; P< 0.05). The modeling of postapheresis apoB kinetics was performed using a nonsteady state condition, taking into account the changing pool size of very low density lipoprotein (VLDL), intermediate density lipoprotein, and LDL apoB. The postapheresis kinetic parameters did not show statistical differences compared with preapheresis parameters in heterozygous FH patients; however, a trend for increases in fractional catabolic rate of LDL (0.24 ± 0.08 vs. 0.35± 0.09 day−1; P = 0.067) and the production of VLDL (13.7 ± 8.3 vs. 21.9 ± 1.6 mg/kg·day; P = 0.076) was observed. These results suggested that the marked decrease in plasma LDL obtained a short time after LDL-apheresis is able to stimulate LDL receptor activity and VLDL production in heterozygous FH.
Heritability of Insulin Secretion and Insulin Action in Women with Polycystic Ovary Syndrome and Their First Degree Relatives1
Authors: Colilla Susan , Cox Nancy J. , Ehrmann David A.
Published: January 2014

Polycystic ovary syndrome (PCOS), one of the most common endocrine disorders of reproductive age women, is associated with an increased risk of type 2 diabetes mellitus. Defects in both insulin action and insulin secretion contribute to this predisposition to diabetes, but the extent to which these defects are heritable among PCOS families has not been examined.

In the present study we used the frequently sampled iv glucose tolerance test to quantitate insulin secretion (AIRg), insulin action (Si), and their product (AIRg × Si) among women with PCOS (n= 33) and their nondiabetic first degree relatives (n = 48). We then quantitated the heritability of these measures from familial correlations estimated within a genetic model.

Familial (spousal, ρMF; parent-offspring, ρPO; and sibling, ρSS) correlations were derived for log-transformed body mass index (BMI) as well as for AIRg, Si, and AIRg × Si, the latter three of which were adjusted for BMI. There was no evidence of significant heritability for either lnBMI or lnSi in these families. In contrast, the sibling correlation (ρSS = 0.74) for lnAIRg was highly significant (χ2 = 7.65; 1 df; P= 0.006). In addition, the parameter quantitating insulin secretion in relation to insulin sensitivity [i.e. ln(AIRg × Si)] was significant among siblings (ρSS = 0.74;χ 2 = 4.32; 1 df; P = 0.04).

In summary, the results of the present study indicate that there is an heritable component to β-cell dysfunction in families of women with PCOS. We conclude that heritability of β-cell dysfunction is likely to be a significant factor in the predisposition to diabetes in PCOS.
The Contribution of Intraabdominal Fat to Gender Differences in Hepatic Lipase Activity and Low/High Density Lipoprotein Heterogeneity1
Authors: Carr Molly C. , Hokanson John E. , Zambon Alberto , Deeb Samir S. , Barrett P. Hugh R. , Purnell Jonathan Q. , Brunzell John D.
Published: January 2014

Hepatic lipase (HL) hydrolyzes triglyceride and phospholipid in low and high density lipoprotein cholesterol (LDL-C and HDL-C, respectively), and elevated HL activity is associated with small, dense atherogenic LDL particles and reduced HDL2-C. Elevated HL activity is associated with increasing age, male gender, high amounts of intraabdominal fat (IAF), and the HL gene (LIPC) promoter polymorphism (C nucleotide at −514). We investigated the mechanisms underlying the difference in HL activity between men (n = 44) and premenopausal women (n = 63).

Men had significantly more IAF (144.5 ± 80.9 vs. 66.5 ± 43.2 cm2, respectively; P< 0.001), higher HL activity (220.9 ± 94.7 vs.129.9 ± 53.5 nmol/mL·min; P < 0.001), more dense LDL (Rf, 0.277 ± 0.032 vs. 0.300 ± 0.024; P = 0.01), and less HDL2-C (0.19 ± 0.10 vs. 0.32± 0.16 mmol/L; P < 0.001) than women. After adjusting for IAF and the LIPC polymorphism, men continued to have higher (but attenuated) HL activity (194.5 ± 80.4 vs.151.0 ± 45.2, respectively; P = 0.007) and lower HDL2-C (0.23 ± 0.11 vs. 0.29 ± 0.14 mmol/L; P = 0.02) than women. Using multiple regression, HL activity remained independently related to IAF (P < 0.001), gender (P < 0.001), and the LIPC genotype (P < 0.001), with these factors accounting for 50% of the variance in HL activity.

These data suggest that IAF is a major component of the gender difference in HL activity, but other gender-related differences, perhaps sex steroid hormones, also contribute to the higher HL activity seen in men compared with premenopausal women. The higher HL activity in men affects both LDL and HDL heterogeneity and may contribute to the gender difference in cardiovascular risk.
Polymorphisms of the Androgen Receptor Gene and the Estrogen Receptor β Gene Are Associated with Androgen Levels in Women1
Authors: Westberg Lars , Baghaei Fariba , Rosmond Roland , Hellstrand Monika , Landén Mikael , Jansson Maria , Holm Göran , Björntorp Per , Eriksson Elias
Published: January 2014

To elucidate the possible role of genetic variation in androgen receptor (AR), estrogen receptor α (ERα), and ERβ on serum androgen levels in premenopausal women, the CAG repeat polymorphism of the AR gene, the TA repeat polymorphism of the ERα gene, and the CA repeat polymorphism of the ERβ gene were studied in a population-based cohort of 270 women. Total testosterone, free testosterone, dehydroepiandrosterone sulfate, androstenedione, 17-hydroxyprogesterone, 3α-androstanediol glucuronide, 17β-estradiol, LH, FSH, and sex steroid hormone-binding globulin (SHBG) were measured in serum samples obtained in the follicular phase of the menstrual cycle. Women with relatively few CAG repeats in the AR gene, resulting in higher transcriptional activity of the receptor, displayed higher levels of serum androgens, but lower levels of LH, than women with longer CAG repeat sequences. The CA repeat of the ERβ gene also was associated with androgen and SHBG levels; women with relatively short repeat regions hence displayed higher hormone levels and lower SHBG levels than those with many CA repeats. In contrast, the TA repeat of the ERα gene was not associated with the levels of any of the hormones measured. Our results suggest that the serum levels of androgens in premenopausal women may be influenced by variants of the AR gene and the ERβ gene, respectively.
Class III Alleles of the Variable Number of Tandem Repeat Insulin Polymorphism Associated with Silencing of Thymic Insulin Predispose to Type 1 Diabetes
Authors: Vafiadis Petros , Ounissi-Benkalha Houria , Palumbo Michael , Grabs Rosemarie , Rousseau Marylène , Goodyer Cynthia G. , Polychronakos Constantin
Published: January 2014

Type 1 diabetes results from autoimmune destruction of the insulin-producing pancreatic β cells. The insulin gene (INS) is also expressed in human thymus, an ectopic expression site likely involved in immune tolerance. The IDDM2 diabetes susceptibility locus maps to a minisatellite composed of a variable number of tandem repeats situated 0.5 kb upstream of INS. Chromosomes carrying the protective long INS variable number of tandem repeats alleles (class III) produce higher levels of thymic INS mRNA than those with the predisposing, short class I alleles. However, complete silencing of thymic INS transcripts from the class III chromosome was found in a small proportion of heterozygous human thymus samples. We hypothesized that the specific class III alleles found on these chromosomes silence rather than enhance thymic insulin expression. To test the prediction that these alleles are predisposing, we developed a DNA fingerprinting method for detecting two putative “silencing” alleles found in two thymus samples (S1, S2). In a set of 287 diabetic children and their parents we found 13 alleles matching the fingerprint of the S1 or S2 alleles. Of 18 possible transmissions, 12 of the S1–S2 alleles were transmitted to the diabetic offspring, a frequency of 0.67, significantly higher than the 0.38 seen in the remaining 142 class III alleles; P = 0.025. This confirms our prediction and represents an additional level of correlation between thymic insulin and diabetes susceptibility, which supports a thymic enhancer effect of the INS variable number of tandem repeats as the mechanism of IDDM2 and refines the contribution of IDDM2 genotyping to diabetes risk assessment.
Germline RET 634 Mutation Positive MEN 2A-related C-Cell Hyperplasias Have Genetic Features Consistent with Intraepithelial Neoplasia
Authors: Diaz-Cano Salvador J. , de Miguel Manuel , Blanes Alfredo , Tashjian Robert , Wolfe Hubert J.
Published: January 2014

C-cell hyperplasias are normally multifocal in multiple endocrine neoplasia type 2A. We compared clonality, microsatellite pattern of tumor suppressor genes, and cellular kinetics of C-cell hyperplasia foci in each thyroid lobe.

We selected 11 females from multiple endocrine neoplasia type 2A kindred treated with thyroidectomy due to hypercalcitoninemia. C-cell hyperplasia foci were microdissected for DNA extraction to analyze the methylation pattern of androgen receptor alleles and microsatellite regions (TP53, RB1, WT1, and NF1). Consecutive sections were selected for MIB-1, pRB1, p53, Mdm-2, and p21WAF1 immunostaining, DNA content analysis, and in situ end labeling. Appropriate tissue controls were run.

Only two patients had medullary thyroid carcinoma foci. Nine informative C-cell hyperplasia patients showed germline point mutation in RET, eight of them with the same androgen receptor allele preferentially methylated in both lobes. C-cell hyperplasia foci showed heterogeneous DNA deletions revealed by loss of heterozygosity of TP53 (12 of 20), RB1 (6 of 14), and WT1 (4 of 20) and hypodiploid G0/G1 cells (14 of 20), low cellular turnover (MIB-1 index 4.5%, in situ end labeling index 0.03%), and significantly high nuclear area to DNA index ratio.

MEN 2A (germline point mutation in RET codon 634) C-cell hyperplasias are monoclonal and genetically heterogeneous and show down-regulated apoptosis, findings consistent with an intraepithelial neoplasia. Concordant X-chromosome inactivation and interstitial gene deletions suggest clone expansions of precursors occurring at a point in embryonic development before divergence of each thyroid lobe and may represent a paradigm for other germline mutations.
Acute Insulin Responses to Leucine in Children with the Hyperinsulinism/Hyperammonemia Syndrome
Authors: Kelly Andrea , Ng Diva , Ferry Robert J. , Grimberg Adda , Koo-McCoy Samantha , Thornton Paul S. , Stanley Charles A.
Published: January 2014

Mutations of glutamate dehydrogenase cause the hyperinsulinism/hyperammonemia syndrome by desensitizing glutamate dehydrogenase to allosteric inhibition by GTP. Normal allosteric activation of glutamate dehydrogenase by leucine is thus uninhibited, leading us to propose that children with hyperinsulinism/hyperammonemia syndrome will have exaggerated acute insulin responses to leucine in the postabsorptive state. As hyperglycemia increases β-cell GTP, we also postulated that high glucose concentrations would extinguish abnormal responsiveness to leucine in hyperinsulinism/hyperammonemia syndrome patients. After an overnight fast, seven hyperinsulinism/hyperammonemia syndrome patients (aged 9 months to 29 yr) had acute insulin responses to leucine performed using an iv bolus of l-leucine (15 mg/kg) administered over 1 min and plasma insulin measurements obtained at −10, −5, 0, 1, 3, and 5 min. The acute insulin response to leucine was defined as the mean increase in insulin from baseline at 1 and 3 min after an iv leucine bolus. The hyperinsulinism/hyperammonemia syndrome group had excessively increased insulin responses to leucine (mean ± sem, 73 ± 21 μIU/ml) compared with the control children and adults (n = 17) who had no response to leucine (1.9 ± 2.7 μU/ml; P < 0.05). Four hyperinsulinism/hyperammonemia syndrome patients then had acute insulin responses to leucine repeated at hyperglycemia (blood glucose, 150–180 mg/dl). High blood glucose suppressed their abnormal baseline acute insulin responses to leucine of 180, 98, 47, and 28 μU/ml to 73, 0, 6, and 19 μU/ml, respectively. This suppression suggests that protein-induced hypoglycemia in hyperinsulinism/hyperammonemia syndrome patients may be prevented by carbohydrate loading before protein consumption.
Efficacy of Ultrasound-Guided Fine-Needle Aspiration Biopsy in the Diagnosis of Complex Thyroid Nodules
Authors: Braga Milena , Cavalcanti Teresa Cristina , Collaço Luiz Martins , Graf Hans
Published: January 2014

Cystic thyroid nodules are considered to be one of the major causes of nondiagnostic and false-negative results on conventional fine-needle aspiration biopsy, thus limiting the potential of this method for the evaluation of complex (solid-cystic) thyroid nodules. Although ultrasound-guided fine-needle aspiration biopsy has emerged as a highly effective diagnostic method for the assessment of nonpalpable and difficult to palpate nodules, its role in complex nodules has not yet been carefully evaluated. In this study, we report the efficacy of ultrasound-guided fine-needle aspiration biopsy in 124 complex nodules in 113 patients. This method proved to be highly effective, yielding a satisfactory specimen for cytological evaluation in 94% of the nodules, suggesting that it is an excellent modality for the evaluation of complex nodules and also for the reevaluation of those nodules with a nondiagnostic result on conventional fine-needle aspiration biopsy.
Neurotropins and Their Receptors Are Expressed in the Human Fetal Ovary
Authors: Anderson Richard A. , Robinson Lynne L. L. , Brooks Julie , Spears Norah
Published: January 2014

Mammalian ovarian development is characterized by a sequential pattern of mitotic proliferation of oogonia, initiation then arrest of meiosis, and primordial follicle formation. The factors regulating these processes are poorly understood. The neurotropins are survival and differentiation factors in the nervous system, acting via high affinity receptors of the trk protooncogene family and the low affinity p75 nerve growth factor receptor, and have also been described in the rodent ovary, where changes in NT4/TrkB gene expression have been detected at the time of primordial follicle formation. There are no data on neurotropin expression in the normal human ovary. We have investigated the expression and localization of neurotropins and their receptors in the midtrimester human fetal ovary (13–21 wk gestation). Expression of mRNA for neurotropins and their receptors was detected by RT-PCR. Clusters of oogonia were found to be the predominant site of NT4 mRNA expression using in situ hybridization. However, at later gestations granulosa cells of primordial follicles showed increased expression, with lesser expression in the enclosed oocytes. NT4 protein was also localized to the granulosa cells by immunohistochemistry and at earlier developmental stages to epithelioid cells, which were mingled with clusters of oogonia not expressing NT4. TrkB receptor protein was localized by immunohistochemistry to germ cells at all gestations examined. The p75 nerve growth factor receptor protein was exclusively expressed in the ovarian stroma. These data demonstrate the expression of neurotropins and their receptors within the human fetal ovary. Developmental changes in the pattern of expression of NT4 around the time of primordial follicle formation suggest that neurotropins may be involved in signaling between somatic cells and germ cells at this crucial stage of ovarian development.
TR Expression and Function in Human Bone Marrow Stromal and Osteoblast-Like Cells
Authors: Siddiqi Ayesha , Parsons Marie P. , Lewis John L. , Monson John P. , Williams Graham R. , Burrin Jacky M.
Published: January 2014

Thyroid hormones influence both bone formation and bone resorption. In vitro studies demonstrate direct effects of thyroid hormones on cells of the osteoblast lineage. Transcriptional regulation by thyroid hormones is mediated by ligand-dependent transcription factors called TRs. The three main T3-binding TR isoforms are TRα1, TRβ1, and TRβ2. TRs have been identified in cells of the osteoblast lineage, but it is still not known whether TR isoform expression differs in primary cultures of human osteoblasts.

We used immunocytochemistry, Western blotting, nuclear binding assays, and transient transfection studies to examine the expression of functional TR isoforms in primary cultures of osteoblasts (hOb) derived from explants of trabecular bone, in human bone marrow stromal cells (hBMS), which are believed to be the source of osteoblast progenitor cells, and for comparison in the transformed human osteosarcoma cell lines MG63 and SaOs-2. TRα1, TRβ1, and TRβ2 proteins were expressed in all cells, although expression was greatest in MG63 > hBMS > SaOs-2 > hOb. Differences between isoforms were also apparent, with TRα1> TRβ1 > TRβ2 in all cell types. Incubation with [125I]T3 confirmed reversible T3 binding to cell nuclei. Specific binding was greatest in MG63 > hBMS > SaOs-2 > hOb. Finally, endogenous TR activity was determined in transfections using a thyroid hormone response element derived from the rat GH gene linked to the luciferase reporter gene. In MG63 and hBMS cells T3 treatment increased luciferase activity 5.5 ± 0.7-fold (P < 0.05), confirming the presence of endogenous receptors. In SaOs-2 and hOb cells, T3 treatment had no effect on thyroid hormone response element-thymidine kinase-luciferase expression, suggesting that in these cells TR expression was too low to be detected.

These results indicate that three main TR isoforms are expressed in cells of the human osteoblast lineage, but that expression and endogenous TR activity are predominantly present in hBMS cells. Whether there are distinct mechanisms of thyroid hormone action mediated by TRα1, TRβ1, and TRβ2 in hOb and hBMS cells remains to be shown.
A Switch in Dehydrogenase to Reductase Activity of 11β-Hydroxysteroid Dehydrogenase Type 1 upon Differentiation of Human Omental Adipose Stromal Cells
Authors: Bujalska Iwona J. , Walker Elizabeth A. , Hewison Martin , Stewart Paul M.
Published: January 2014

As exemplified in patients with Cushing’s syndrome, glucocorticoids play an important role in regulating adipose tissue distribution and function, but circulating cortisol concentrations are normal in most patients with obesity. However, human omental adipose stromal cells (ASCs) can generate glucocorticoid locally through the expression of the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) type 1 (11β-HSD1), which, in intact cells, has been considered to be an oxoreductase, converting inactive cortisone (E) to cortisol (F). Locally produced F can induce ASC differentiation, but the relationship between 11β-HSD1 expression and adipocyte differentiation is unknown. Primary cultures of paired omental (om) and sc ASC and adipocytes were prepared from 17 patients undergoing elective abdominal surgery and cultured for up to 14 d. Expression and activity of 11β-HSD isozymes were analyzed together with early (lipoprotein lipase) and terminal (glycerol 3 phosphate dehydrogenase) markers of adipocyte differentiation. On d 1 of culture, 11β-HSD1 activity in intact om ASCs exceeded oxoreductase activity in every patient (78.9 ± 24.9 vs. 15.8 ± 3.7 [mean ± se] pmol/mg per hour, P < 0.001), and in sc ASCs, relative activities were similar (40.6 ± 12.2 vs. 36.9 ± 8.8). Conversely, in freshly isolated om adipocytes, reductase activity exceeded dehydrogenase activity (23.6 ± 1.5 vs. 6.2 ± 0.8 pmol/mg per hour, P < 0.01). Following 14 d of culture in serum-free conditions with addition of 10 nm insulin (Ctr) or insulin with 100 nm F (+F), lipoprotein lipase/18S RNA levels increased in both the Ctr- and +F-treated ASCs, but glycerol 3 phosphate dehydrogenase increased only in the +F cultures. In both cases, however, 11β-HSD1 oxoreductase activity exceeded dehydrogenase activity (Ctr: 53.3 ± 9.0 vs. 32.4 ± 10.5, P < 0.05; +F: 65.6 ± 15.6 vs. 37.1 ± 11.5 pmol/mg per hour, P < 0.05), despite no significant changes in 11β-HSD1 mRNA levels. In sc ASCs, dehydrogenase activity was similar to reductase activity in both Ctr- and +F-treated cells. Type 2 11β-HSD expression was undetectable in each case. These data show that in intact, undifferentiated om ASCs, 11β-HSD1 acts primarily as a dehydrogenase, but in mature adipocytes oxoreductase activity predominates. Because glucocorticoids inhibit cell proliferation, we postulate that 11β-HSD1 activity in uncommitted ASCs may facilitate proliferation rather than differentiation. Once early differentiation is initiated, a “switch” to 11β-HSD1 oxoreductase activity generates F, thus promoting adipogenesis. Site-specific regulation of the set-point of 11β-HSD1 activity may be an important mechanism underpinning visceral obesity.
Frequent Occurrence of an Intron 4 Mutation in Multiple Endocrine Neoplasia Type 1
Authors: Turner Jeremy J. O. , Leotlela Poloko D. , Pannett Anna A. J. , Forbes Simon A. , Bassett J. H. Duncan , Harding Brian , Christie Paul T. , Bowen-Jones David , Ellard Sian , Hattersley Andrew , Jackson Charles E. , Pope Richard , Quarrell Oliver W. , Trembath Richard , Thakker Rajesh V.
Published: January 2014

MEN1 is an autosomal dominant disorder characterized by parathyroid, pituitary, and pancreatic tumors. The MEN1 gene is located on chromosome 11q13 and encodes a 610-amino acid protein. MEN1 mutations are of diverse types and are scattered throughout the coding region, such that almost every MEN1 family will have its individual mutation. To further characterize such mutations we ascertained 34 unrelated MEN1 probands and undertook DNA sequence analysis. This identified 17 different mutations in 24 probands (2 nonsense, 2 missense, 2 in-frame deletions, 5 frameshift deletions, 1 frameshift deletional-insertion, 3 frameshift insertions, 1 donor splice site mutation, and a g→a transition that resulted in a novel acceptor splice site in intron 4). The intron 4 mutation was found in 7 unrelated families, and the tumors in these families varied considerably, indicating a lack of genotype-phenotype correlation. However, this intron 4 mutation is the most frequently occurring germline MEN1 mutation (∼10% of all mutations), and together with 5 others at codons 83–84, 118–119, 209–211, 418, and 516, accounts for 36.6% of all mutations, a finding that indicates an approach for identifying the widely diverse MEN1 mutations.
Acute Changes of Bone Turnover and PTH Induced by Insulin and Glucose: Euglycemic and Hypoglycemic Hyperinsulinemic Clamp Studies
Authors: Clowes Jackie A. , Robinson Robert T. , Heller Simon R. , Eastell Richard , Blumsohn Aubrey
Published: January 2014

Bone turnover is acutely suppressed after feeding or oral glucose. Insulin infusion suppresses bone turnover and might mediate this effect, but this is confounded by a possible direct effect of hypoglycemia. We examined the effect of euglycemic hyperinsulinemia and hypoglycemic hyperinsulinemia on bone turnover using an insulin clamp. Sixteen men participated in this double-blind crossover study. Clamp induction involved infusion of insulin (80 mU/m2·min) while maintaining euglycemia (5 mmol/liter) for 40 min with a variable rate dextrose infusion. Glucose was lowered to 2.5 mmol/liter (hypoglycemic clamp) or maintained at 5 mmol/liter (euglycemic clamp) for a further 105 min. Nine controls received a matched saline infusion. Measurements included serum C-terminal telopeptide of type I collagen, procollagen type I N-terminal propeptide, osteocalcin, and PTH.

Induction of hyperinsulinemia resulted in a reduction in PTH (27% ± 5; P < 0.01), but no significant change in bone turnover from baseline. Hypoglycemic clamp resulted in suppression of serum C-terminal telopeptide of type I collagen by 34% ± 3, procollagen type I N-terminal propeptide by 15% ± 1, osteocalcin by 5% ± 1, and PTH by a further 12% ± 5 (all P < 0.05). By contrast, there was no significant change in any marker of bone turnover during euglycemic clamp.

Postprandial hyperinsulinemia is unlikely to explain the acute suppression of bone turnover with feeding. The reduction in bone turnover during hypoglycemia may be related to hypoglycemia itself, acute changes in PTH, or other hormones released in response to hypoglycemia.