Novel model to study the physiological effects of temporary or prolonged sex steroid deficiency in male mice.

Sex steroids are critical for skeletal development and maturation during puberty as well as for skeletal maintenance during adult life. However, the exact time during puberty when sex steroids have the highest impact as well as the ability of bone to recover from transient sex steroid deficiency is unclear. Surgical castration is a common technique to study sex steroid effects in rodents, but it is irreversible, invasive, and associated with metabolic and behavioral alterations. Here, we used a low dose (LD) or a high dose (HD) of gonadotropin-releasing hormone antagonist to either temporarily or persistently suppress sex steroid action in male mice, respectively. The LD group, a model for delayed puberty, did not show changes in linear growth or body composition, but displayed reduced trabecular bone volume during puberty, which fully caught up at adult age. In contrast, the HD group, representing complete pubertal suppression, showed a phenotype reminiscent of that observed in surgically castrated rodents. Indeed, HD animals exhibited severely impaired cortical and trabecular bone acquisition, decreased body weight and lean mass, and increased fat mass. In conclusion, we developed a rodent model of chemical castration that can be used as an alternative to surgical castration. Moreover, the transient nature of the intervention enables to study the effects of delayed puberty and reversibility of sex steroid deficiency.NEW & NOTEWORTHY We developed a rodent model of chemical castration, which can be used as an alternative to surgical castration. Moreover, the transient nature of the intervention enables to study the effects of delayed puberty and reversibility of sex steroid deficiency.

Increasing intravenous glucose load in the presence of normoglycemia: effect on outcome and metabolism in critically ill rabbits.

OBJECTIVES: Endocrine disturbances and a feeding-resistant wasting syndrome, characterized by a negative protein balance, promote delayed recovery and poor outcome of critical illness. Parenteral nutrition alone cannot counteract the hypercatabolic state, possibly in part as a result of aggravation of the hyperglycemic response to illness. In critically ill rabbits, we investigated the impact of varying amounts of intravenous glucose while maintaining normoglycemia on mortality, organ damage, and markers of catabolism/anabolism. DESIGN: Prospective, randomized laboratory investigation. SETTING: University animal and molecular laboratory. SUBJECTS: Three-month-old male rabbits. INTERVENTIONS: Critically ill rabbits were randomized into a fasting group, a standard parenteral nutrition group, and two groups receiving either intermediate or high additional physiological amounts of intravenous glucose while maintained normoglycemic with insulin. These groups were compared with a hyperglycemic group and healthy rabbits. Protein and lipid load was equal for all fed groups. MEASUREMENTS AND MAIN RESULTS: Varying intravenous glucose load did not affect mortality or organ damage provided hyperglycemia was prevented. Fasted critically ill rabbits lost weight, which was attenuated by increasing intravenous glucose load. As compared with healthy rabbits, mRNA expression and/or activity of several ubiquitin-proteasome pathway components, cathepsin-L and calpain-1, was elevated in skeletal muscle of fasted critically ill rabbits. Intravenous feeding was able to counteract this response. Excessive glucose load and/or hyperglycemia, however, reduced the protective effect of feeding. Genes investigated in the diaphragm and myocardium revealed roughly a similar response. Except in the normoglycemic group with intermediate glucose load, circulating thyroid hormone and insulin-like growth factor-1 levels decreased, most pronounced in hyperglycemic rabbits. CONCLUSIONS: Increasing intravenous glucose infusion within the physiological range, while maintaining normoglycemia, was safe for organ function and survival of critically ill rabbits. Concomitantly, it reduced the catabolic responses as compared with fasting. Whether this has a beneficial effect on muscle function and mass remains to be investigated.

Insulin-like growth factor-II regulates maternal hemodynamic adaptation to pregnancy in rats.

The relationship between maternal plasma volume (PV) expansion and fetal growth is well established, but the underlying mechanisms remain unclear. Here, we examined the influence of maternal body weight and fetoplacental mass on gestational PV increment in the rat. Because IGF-I and IGF-II have growth-promoting and vasoactive properties, their relationship to PV expansion and fetoplacental growth was also studied. In normal rats, the gradual expansion of PV (+35% at day 22, i.e., term) was accompanied by a rise in circulating IGF-II (+45%) and a considerable drop in IGF-I (-73%). Increased maternal body weight induced by an obesogenic diet did not influence PV and circulating IGFs compared with rats on the standard diet. Combining the results from both diets, circulating IGF-II was the principal correlate of PV. A second experiment examined the effect of fetoplacental mass reduction by surgically removing half of the gestational sacs at day 16. This procedure reduced maternal PV and circulating IGF-II at term by 14% and 20%, respectively. We then investigated the effect of a constant infusion of IGF-II (1 mgxkg(-1)xday(-1)) from day 16, which raised circulating IGF-II by 38% and found increased PV (+19%) and a larger placental trophospongial area (+29%) at term. Our results indicate that the placenta, the primary source of IGF-II synthesis in pregnancy, drives PV expansion, and that IGF-II is among the regulatory factors of the gestational PV increment. Further studies should clarify whether IGF-II directly affects vascular function and/or indirectly promotes the secretion of placenta-derived vasoactive substances.

Hypogonadism in male outpatients with sarcoidosis.

Hypogonadism is assumed to be present in sarcoidosis. Nevertheless, a comparison of circulating sex hormone concentrations of male sarcoidosis patients with those of healthy men has never been done. Moreover, it remains unknown if hypogonadism may contribute to a reduced muscle function, exercise intolerance, diminished vitality and depressed mood in male sarcoidosis patients. Pulmonary function, muscle function, exercise tolerance, vitality, mood, circulating sex hormone concentrations and C-reactive protein were assessed in 30 male sarcoidosis patients and 26 age-matched men with a normal pulmonary function. On average, patients had a restrictive pulmonary function, worse inspiratory and quadriceps muscle function, functional exercise intolerance, diminished vitality, depressed mood and increased systemic inflammation. Moreover, patients had significantly lower circulating (free) testosterone concentrations, while circulating sex hormone-binding globulin tended to be lower (p=0.0515). Circulating gonadotrophin concentrations were comparable. Non-significant relationships were found between sex hormones, clinical outcomes and C-reactive protein in patients with sarcoidosis. A significant number of male outpatients with sarcoidosis (46.7%) had low circulating testosterone concentrations, which was most probably caused by hypogonadotrophism. The clinical relevance of hypogonadism in male outpatients with sarcoidosis, however, remains currently unknown. Indeed, poor inspiratory and quadriceps muscle function, exercise intolerance, diminished vitality and depressed mood were not related to hypogonadism in these patients.

Maternal body size and birth weight: can insulin or adipokines do better?

Overweight gravidas and gravidas with a robust weight gain have an accrued risk of delivering a large-for-gestational age (LGA) baby. Here, we examined whether the measurement of insulin and adipokines--peptides secreted mainly by adipose tissue--at the glucose challenge test (GCT) improves the prediction of birth weight. We studied 631 singleton pregnancies at 24 to 29 weeks' gestational age (GA) with data on height, baseline body weight (BW), and BW change between baseline and the GCT. In addition to glucose and insulin, we measured adiponectin, leptin, soluble leptin receptor (the main leptin-binding protein), and tumor necrosis factor alpha. We found that birth weight was related to maternal height, baseline BW, and BW change, and also--albeit less strongly--to insulin, adiponectin, leptin, and soluble leptin receptor concentrations. In multiple regression analyses, body size parameters explained approximately 10% of the variance in birth weight, of which BW change was the most important correlate, but the metabolic markers added only approximately 2% variance, with leptin alone adding 1.4%. Gravidas carrying a small-for-GA (SGA) fetus were more likely to have a leptin value in the highest quartile than those with an appropriate-for-GA fetus (odds ratio, 2.6; 95% confidence interval, 1.1-6.3; P = .04), but there were no other differences in the metabolic markers between SGA or LGA and appropriate-for-GA pregnancies. In conclusion, measuring insulin and adipokines at the GCT has limited, if any, clinical benefit to predict which fetuses will be SGA or LGA at birth.

Nuchal translucency thickness measurements for fetal aneuploidy screening: Log NT-MoM or Delta-NT, performer-specific medians and ultrasound training.

OBJECTIVES: To evaluate in fetal aneuploidy screening the desirability of using Fetal Medicine Foundation (FMF) normal medians of nuchal translucency thickness (NT) measurements or performer-specific medians, and whether the NT measurements should be expressed as Delta-NT or Log NT-MoM values. SETTINGS: First trimester-combined screening programme in a low risk population in Flanders, Belgium (Algemeen Medisch Laboratorium, Antwerp). METHODS: Pregnancies unaffected by trisomy 21 (T21) were screened by FMF-trained or other ultrasonographers. Performer-specific NT medians were established for FMF-trained and other ultrasonographers. NCSS Statistical Software was used to establish probability plots for Log NT-MoM and Delta-NT values, relative to performer-specific references or to the FMF-reference. RESULTS: A total of 16,096 pregnancies were evaluated. Six FMF-trainees and five other ultrasonographers each performed between 83 and 658 NT measurements. For the FMF-trainees, FMF-specific NT-MoM medians were close to one at a crown-rump length (CRL) between 50 and 80 mm, whereas the population-specific NT-MoM medians of the other ultrasonographers were close to one at a CRL between 40 and 80 mm. Performer-specific Delta-NT values fitted a Gaussian distribution between the 5th and 90th percentiles, while for the Log NT-MoM values this was between the 10th and 95th percentiles. CONCLUSION: We conclude that (i) the use of screening would benefit from performer-specific NT-medians based on Log NT-MoM values; (ii) the use of Log NT-MoM values is marginally better than the use of delta-NT MoMs; and (iii) NT measurements are valid at about 10 weeks (crown-rump length 40-45 mm) as well as at 11-13 weeks.

Maternal Methyl-Group Donor Intake and Global DNA (Hydroxy)Methylation before and during Pregnancy.

It is still unclear to which extent methyl-group intake during pregnancy can affect maternal global DNA (hydroxyl)methylation. Pregnancy methylation profiling and its link with methyl-group intake in a healthy population could enhance our understanding of the development of pregnancy related disorders. One hundred forty-eight women were enrolled in the MANOE (MAternal Nutrition and Offspring's Epigenome) study. Thiry-four women were enrolled before pregnancy and 116 during the first trimester of pregnancy. Global DNA (hydroxy)methylation in blood using LC-MS/MS and dietary methyl-group intake (methionine, folate, betaine, and choline) using a food-frequency questionnaire were estimated pre-pregnancy, during each trimester, and at delivery. Global DNA (hydroxy)methylation levels were highest pre-pregnancy and at weeks 18-22 of pregnancy. We observed a positive relation between folic acid and global DNA methylation (p = 0.04) and hydroxymethylation (p = 0.04). A high intake of methionine pre-pregnancy and in the first trimester showed lower (hydroxy)methylation percentage in weeks 11-13 and weeks 18-22, respectively. Choline and betaine intake in the first weeks was negatively associated with hydroxymethylation. Women with a high intake of these three methyl groups in the second and third trimester showed higher hyrdoxymethylation/methylation levels in the third trimester. To conclude, a time trend in DNA (hydroxy)methylation was found and women with higher methyl-group intake showed higher methylation in the third trimester, and not in earlier phases of pregnancy.

Tissue deiodinase activity during prolonged critical illness: effects of exogenous thyrotropin-releasing hormone and its combination with growth hormone-releasing peptide-2.

Prolonged critical illness is characterized by reduced pulsatile TSH secretion, causing reduced thyroid hormone release and profound changes in thyroid hormone metabolism, resulting in low circulating T(3) and elevated rT(3) levels. To further unravel the underlying mechanisms, we investigated the effects of exogenous TRH and GH-releasing peptide-2 (GHRP-2) in an in vivo model of prolonged critical illness. Burn-injured, parenterally fed rabbits were randomized to receive 4-d treatment with saline, 60 microg/kg.h GHRP-2, 60 microg/kg.h TRH, or 60 microg/kg.h TRH plus 60 microg/kg.h GHRP-2 started on d 4 of the illness (n = 8/group). The activities of the deiodinase 1 (D1), D2, and D3 in snap-frozen liver, kidney, and muscle as well as their impact on circulating thyroid hormone levels were studied. Compared with healthy controls, hepatic D1 activity in the saline-treated, ill animals was significantly down-regulated (P = 0.02), and D3 activity tended to be up-regulated (P = 0.06). Infusion of TRH and TRH plus GHRP-2 restored the catalytic activity of D1 (P = 0.02) and increased T(3) levels back within physiological range (P = 0.008). D3 activity was normalized by all three interventions, but only addition of GHRP-2 to TRH prevented the rise in rT(3) seen with TRH alone (P = 0.02). Liver D1 and D3 activity were correlated (respectively, positively and negatively) with the changes in circulating T(3) (r = 0.84 and r = -0.65) and the T(3)/rT(3) ratio (r = 0.71 and r = -0.60). We conclude that D1 activity during critical illness is suppressed and related to the alterations within the thyrotropic axis, whereas D3 activity tends to be increased and under the joint control of the somatotropic and thyrotropic axes.

Exogenous corticosteroids and in utero oxygenation modulate indices of fetal insulin secretion.

Low birth weight has long-term effects on glucose-insulin homeostasis. Factors that could mediate intra-uterine "programing" of glucose homeostasis include endogenous and exogenous glucocorticoids, adipose tissue-secreted factors such as adiponectin, and in utero hypoxia. Here, we studied 123 fetuses with gestational age (GA) between 25 and 37 wk and birth weight sd score (BW SDS) between -2.79 and 2.42. We measured proinsulin, C-peptide, insulin, and adiponectin in umbilical vein (UV) plasma and calculated the proinsulin to insulin ratio as a measure of beta-cell secretory function. These indices were related to GA, BW SDS, time since the last maternal betamethasone administration, and blood gas data. Insulin and C-peptide were correlated with BW SDS but not GA, whereas the proinsulin to insulin ratio was inversely correlated with BW SDS. The proinsulin to insulin ratio was raised (P = 0.002) in fetuses with UV PO(2) less than or equal to 21.3 mm Hg (i.e. the 50th percentile) compared with those with PO(2) more than 21.3 mm Hg, inferring that in utero hypoxia engenders beta-cell secretory dysfunction. Proinsulin, insulin, and C-peptide were markedly but transiently (<24 h) elevated after maternal betamethasone administration, returning thereafter to concentrations measured in noncorticosteroid-treated fetuses. However, there was considerable variability within the less than 24-h betamethasone group: the indices of insulin secretion were related to UV PO(2), suggesting that hypoxia attenuates the responsiveness of fetal beta-cells to corticosteroids. Adiponectin was not related to any of the insulin indices. In conclusion, we have identified two environmental signals that modulate fetal insulin output: maternal corticosteroids produce a transient surge in fetal insulin synthesis and secretion, whereas in utero hypoxia disturbs the insulin secretory process.

Bone and muscle protective potential of the prostate-sparing synthetic androgen 7alpha-methyl-19-nortestosterone: evidence from the aged orchidectomized male rat model.

This study reports the preclinical evaluation of the bone and muscle protective potential of the synthetic androgen 7alpha-methyl-19-nortestosterone (MENTtrade mark), as assessed in the aged orchidectomized rat model. Aged (13-month-old) orchidectomized Wistar rats were treated with different doses of MENT (4, 12 or 36 microg/day) subcutaneously for 16 weeks via mini-osmotic pumps. Analysis of the effects of androgen deficiency versus MENT replacement was performed using quantitative computed tomography (pQCT), dual energy X-ray absorptiometry (DEXA) and biochemical markers of bone turnover. At the end of the study period, prostate weight in orchidectomized rats treated with low- (4 microg/day) or mid-dose (12 mug/day) MENT remained significantly lower compared to the sham-operated animals (-47% and -25%, respectively). High-dose MENT (36 microg/day), on the other hand, induced prostate hypertrophy (+21% versus sham). Low-, mid- and high-dose MENT were found to be effective in suppressing the acceleration of bone remodeling following orchidectomy, as assessed by osteocalcin and deoxypyridinoline. In addition, low-, mid- and high-dose were able to prevent the orchidectomy-induced bone loss, as evaluated by DEXA at the femur and total-body and by pQCT at the femur. Compared to sham-operated animals, the low- and mid-dose MENT groups showed no decline in lean body mass and no muscle atrophy (as measured by m. quadriceps weight) at 16 weeks, whereas high-dose MENT was associated with a significant decline in lean body mass (-8.5% versus sham) and quadriceps weight (-10.6%). We conclude that, in the aged orchidectomized rat model, low- and mid-doses of the synthetic androgen MENT have bone and muscle protective effects and do not induce prostate hypertrophy. The bone protective action of high-dose MENT, however, occurs at the expense of muscle wasting and prostate hypertrophy. Our findings support the need for human studies to explore the potential of MENT as an option for androgen replacement in aging men.

Role of the androgen receptor in skeletal homeostasis: the androgen-resistant testicular feminized male mouse model.

UNLABELLED: The role of androgen receptor-mediated androgen action on bone was investigated in testicular feminized male (Tfm) mice. Cortical bone was found to be unresponsive to testosterone (T) in orchidectomized Tfm mice, whereas cortical thickness as well as trabecular BMD and structure were fully maintained by T in the corresponding Tabby control mice. These data show an essential role for androgen receptor-mediated androgen action in periosteal bone formation. INTRODUCTION: Androgens can affect the male skeleton both directly-through activation of the androgen receptor (AR)-and indirectly-through stimulation of estrogen receptors after aromatization. We assessed the importance of AR-mediated androgen action on bone in a mouse model of androgen resistance. MATERIALS AND METHODS: Eight-week-old androgen-resistant testicular feminized male (Tfm) and Tabby control mice were orchidectomized (ORX) and treated for 4 weeks with a slow-release testosterone (T) pellet (delivering 167 microg/day) or a placebo pellet. A comprehensive analysis of the skeletal effects of androgen deficiency and replacement was performed using histomorphometry, QCT, and biochemical assessment of bone turnover. RESULTS: As expected, T increased trabecular BMD, volume, number, and width in ORX Tabby mice. In ORX Tfm mice, however, T had less effect on trabecular BMD and no effect on trabecular bone structure. T action on trabecular bone was associated with opposite changes in bone turnover: trabecular and endocortical bone turnover and serum levels of osteocalcin were all reduced by T in ORX Tabby mice, but not in ORX Tfm mice. T also increased cortical thickness (+16%), area, and density in ORX Tabby mice, but not in Tfm mice, resulting in greater bone strength in the Tabby control strain. The positive effects of T on cortical bone reflected a stimulatory effect on periosteal bone formation (+137%), which was again absent in Tfm mice. CONCLUSIONS: These data show that, in male mice, AR-mediated T action is essential for periosteal bone formation and contributes to trabecular bone maintenance.

A novel in vivo rabbit model of hypercatabolic critical illness reveals a biphasic neuroendocrine stress response.

High doses of GH, used to induce anabolism in prolonged critically ill patients, unexpectedly increased mortality. To further explore underlying mechanisms, a valid animal model is needed. Such a model is presented in this study. Seven days after arterial and venous cannulae placement, male New Zealand White rabbits were randomly allocated to a control or a critically ill group. To induce prolonged critical illness, a template controlled 15% deep dermal burn injury was imposed under combined general and regional (paravertebral) anesthesia. Subsequently, critically ill rabbits received supplemental analgesia and were parenterally fed with glucose, insulin, amino acids, and lipids. On d 1 and d 8 after randomization, acute and chronic spontaneous hormonal profiles of GH, TSH, and PRL secretion were obtained by sampling blood every 15 min for 7 h. Furthermore, GH, TSH, and PRL responses to an iv bolus of GH-releasing peptide 2 (GHRP-2) + TRH were documented on d 0, 1, and 8. Hemodynamic status and biochemical parameters were evaluated on d 0, 1, 3, 5, and 8, after which animals were killed and relative wet weight and water content of organs was determined. Compared with controls, critically ill animals exhibited transient metabolic acidosis on d 1 and weight loss, organ wasting, systolic hypertension, and pronounced anemia on d 8. On d 1, pulsatile GH secretion doubled in the critically ill animals compared with controls, and decreased again on d 8 in the presence of low plasma IGF-I concentrations from d 1 to d 8. GH responses to GHRP-2 + TRH were elevated on d 1 and increased further on d 8 in the critically ill animals. Mean TSH concentrations were identical in both groups on d 1 and 8, in the face of dramatically suppressed plasma T(4) and T(3) concentrations in the critically ill animals. PRL secretion was impaired in the critically ill animals exclusively on d 8. TSH and PRL responses to GHRP-2 and TRH were increased only on d 1. In conclusion, this rabbit model of acute and prolonged critical illness reveals several of the clinical, biochemical, and endocrine manifestations of the human counterpart.

Metabolic, endocrine, and immune effects of stress hyperglycemia in a rabbit model of prolonged critical illness.

Stress hyperglycemia is frequent in critically ill patients. The aim of this study was to investigate the effect of blood glucose control with insulin on endocrine, metabolic, and immune function in an animal model of severe injury. Seventy-two hours after alloxan injection and exogenous insulin infusion combined with continuous iv parenteral nutrition, male New Zealand White rabbits received a burn injury and were allocated to a normoglycemic (n = 17) or hyperglycemic (n = 13) group. In the normoglycemic group, blood glucose levels were kept between 3.3 and 6.1 mmol/liter by insulin infusion, whereas in the hyperglycemic group blood glucose levels were maintained at 13.8-16.6 mmol/liter. Blood was drawn for biochemical analysis at regular time points. At 24 and 72 h after burn injury, immune function of monocytes was assessed in vitro. Maintenance of normoglycemia with exogenous insulin after severe trauma to a large extent prevented weight loss, lactic acidosis, and hyponatremia. Furthermore, within 3 d after injury, the intervention improved phagocytosis of monocytes investigated in fresh cells by more than a mean 150% (P = 0.006) and after 24-h incubation with or without lipopolysaccharide by more than a mean 4-fold (P = 0.001) and 2-fold (P = 0.05), respectively. Oxidative killing after 24-h incubation was also improved by 2-fold (P = 0.05), but no effect on chemotaxis was detected. Concomitantly, inflammation and stress-induced growth hormone hypersecretion were suppressed. Prevention of catabolism, acidosis, excessive inflammation, and impaired innate immune function may explain previously documented beneficial effects of intensive insulin therapy on outcome of critical illness.

Placental GH, IGF-I, IGF-binding protein-1, and leptin during a glucose challenge test in pregnant women: relation with maternal body weight, glucose tolerance, and birth weight.

The prediction of birth weight may be improved by the measurement of hormones or growth factors in the mother. We measured body weight (BW) and plasma levels of placental GH (PGH), IGF-I, IGF-binding protein-1 (IGFBP-1), and leptin at the time of the glucose challenge test (GCT) in 289 women, who were pregnant with a single fetus, between 24 and 29 wk gestational age (GA). Delivery occurred 12 +/- 2 (mean +/- SD) wk later. First, we examined which variables regulate these hormonal factors. Multiple regression showed that PGH concentrations were determined by GA at sampling and were negatively related to BW. IGF-I levels were mainly determined by PGH, and also by insulin, BW, and (negatively) age. IGFBP-1 concentrations were negatively determined by BW, insulin, and IGF-I. BW was also a powerful determinant of leptin levels, with insulin as a less robust determinant. Second, we examined the relation to glucose levels. PGH, IGF-I, and IGFBP-1 concentrations were not correlated with post-GCT glucose levels and were comparable in women with a normal or disturbed GCT (glucose >/=7.8 mmol/liter; n = 72). Finally, we examined the relation with birth weight and placental weight. Birth weight, corrected for GA and stratified into percentile groups, and the ponderal index at birth were strongly related to maternal BW, but not to maternal PGH, IGF-I, or IGFBP-1 levels. Neither was maternal leptin related to birth weight, but leptin concentrations were slightly higher in women who delivered obese babies. Placental weight was not related to any of the hormonal factors. This prospective study indicates that the variation in circulating PGH, IGF-I, IGFBP-1, and leptin between 24 and 29 wk of pregnancy is strongly dependent on maternal BW, but is unrelated to glucose tolerance. In addition, the measurement of PGH, IGF-I, IGFBP-1, or leptin at the time of the GCT is not useful clinically to predict birth weight.

Arthralgia induced by endocrine treatment for breast cancer: A prospective study of serum levels of insulin like growth factor-I, its binding protein and oestrogens.

BACKGROUND: Aromatase inhibitors (AIs) frequently induce or enhance musculoskeletal problems (AI-induced musculoskeletal syndrome (AIMSS)) which sometimes are debilitating. Apart from low oestrogen levels, underlying mechanisms are unknown and likely multiple. We previously hypothesised a role for the growth hormone/insulin like growth factor-I (IGF-I) axis. Here, we report the effect of tamoxifen and AI on IGF-I, IGF binding protein-3 (IGFBP-3) and oestrogen levels from a prospective study. MATERIALS AND METHODS: Postmenopausal women with an early breast cancer scheduled to start adjuvant endocrine therapy with an AI or tamoxifen were recruited. A rheumatologic questionnaire was completed and serum was collected for assessment of IGF-I, IGFBP-3 and oestrogen levels. Re-evaluation was done after 3, 6 and 1 2months of therapy. RESULTS: 84 patients started on tamoxifen (n=42) or an AI (n=42). 66% of the latter group experienced worsening of pre-existing or de novo complaints in joint and/or muscle, compared to 29% of tamoxifen-treated patients. AI therapy resulted in elevated IGF-I levels with a statistically significant increase at 6months (p=0.0088), whereas tamoxifen users were characterised by a decrease in IGF-I levels at all follow-up times (p<0.0004). No effect on IGFBP-3 was seen in the latter group. AI-users, however, showed decreased IGFBP-3 levels at 12 months (p=0.0467). AIMSS was characterised by a decrease in IGFBP-3 levels (p=0.0007) and a trend towards increased IGF-I/IGFBP-3 ratio (p=0.0710). CONCLUSION: These findings provide preliminary evidence that AI-induced musculoskeletal symptoms are associated with changes in the growth hormone (GH)/IGF-I axis.

Glycated hemoglobin in pregnancies at increased risk for gestational diabetes mellitus.

OBJECTIVE: The glycated hemoglobin (HbA(1c)) value is increasingly used for the detection of (pre)diabetes, but HbA(1c) decreases during pregnancy. We sought to identify clinical and metabolic correlates of HbA(1c) in pregnancies at increased risk for gestational diabetes mellitus (GDM). STUDY DESIGN: We prospectively studied 335 gravidas who received a 3-h 100g oral glucose tolerance test (OGTT) at 24-32 weeks, in most cases after an abnormal glucose challenge test. Several indices of insulin sensitivity and secretion were computed from fasting measurements and the OGTT. RESULTS: HbA(1c) concentrations gradually increased in diet-treated and insulin-treated GDM gravidas compared with non-GDM gravidas. HbA(1c) was higher if the insulin peak was delayed until 180 min compared with 60 or 120 min. Stepwise regression identified the homeostasis modeling assessment of insulin resistance (HOMA-IR) as the first-rank correlate. Other correlates were ethnicity, a low insulin-to-glucose response at 60 min, and gestational age. The HbA(1c) value corresponding to a fasting glucose of 5.1 mmol/l (diagnostic of GDM) was 2 mmol/mol (~0.2%) higher if sampling occurred at 29-32 vs. 24-28 weeks or if ancestry was non-European vs. European. CONCLUSION: HbA(1c) is strongly associated with insulin resistance; in addition, HbA(1c) captures the first-phase insulin response. However, HbA(1c) varies with gestational age and ethnicity.

Oxidant balance markers at birth in relation to glycemic and acid-base parameters.

In diabetic pregnancies, suboptimal glycemic control is a risk factor for fetal acidemia and stillbirth. We hypothesized that the diabetic intrauterine milieu (hyperglycemia, hyperinsulinemia, changes in acid-base status) might predispose to oxidative stress. We studied 70 newborns whose mothers had pregestational diabetes (58 with type 1 diabetes mellitus) and 71 control newborns from nondiabetic mothers. Protein carbonyls (PCs), malondialdehyde, and 8-hydroxy-2'deoxyguanosine were measured in umbilical vein plasma as a reflection of protein, lipid, and DNA oxidative damage, respectively; glutathione peroxidase-3 (GPx3), an important circulating antioxidant enzyme, was also assayed. Despite satisfactory glycemic control in the majority of diabetic mothers, their newborns showed higher birth weight and relative hyperglycemia, hyperinsulinemia, and respiratory acidemia. The oxidant balance marker concentrations were not different at the P < .05 level between the 2 groups, and there was no relationship to maternal hemoglobin A(1C) levels in the diabetic group. However, in the entire sample, increasing glucose levels at birth were related to lower GPx3 and higher PC concentrations; and GPx3 and PC concentrations were inversely correlated. In addition, a depressed pH or larger base-deficit at birth was related to higher PC and 8-hydroxy-2'deoxyguanosine concentrations. In conclusion, oxidant balance markers at birth are not affected by maternal diabetes per se and its long-term glycemic control, yet some markers are acutely tuned to metabolic cues including glucose and the acid-base environment.

Effect of intensive insulin therapy on the somatotropic axis of critically ill children.

CONTEXT: Intensive insulin therapy (IIT) improved outcome in the adult and pediatric intensive care unit (PICU) compared with conventional insulin therapy (CIT). IIT did not increase the anabolic hormone IGF-I in critically ill adults, but feeding in critically ill children and pediatric hormonal responses may differ. Twenty-five percent of the children with IIT experienced hypoglycemia, which may have evoked counterregulatory responses. OBJECTIVE: We hypothesized that IIT reactivates the somatotropic axis and anabolism in PICU patients. DESIGN: This was a preplanned subanalysis of a randomized controlled trial on IIT. PATIENTS: We studied 369 patients who stayed in PICU for at least 3 d (study 1) and 126 patients in a nested case-control study (study 2). MAIN OUTCOME MEASURES: Circulating insulin, C-peptide, GH, IGF-I, bioavailable IGF-I, IGF-binding protein (IGFBP)-1, IGFBP-3, and acid-labile subunit were analyzed upon admission and d 3. In the nested case-control study, the somatotropic axis, cortisol, and glucagon were analyzed before and after hypoglycemia. RESULTS: On d 3, C-peptide was more than 10-fold lower (P < 0.0001) in the IIT group than in the CIT group. IIT increased circulating GH (P = 0.04) and lowered bioavailable IGF-I (P = 0.002). IIT also decreased IGFBP-3 (P = 0.0005) and acid-labile subunit (P = 0.007), while increasing IGFBP-1 (P = 0.04) and the urea/creatinine ratio, a marker of catabolism (P = 0.03). In the nested case-control study, IGFBP-1 was increased after hypoglycemia, whereas the somatotropic axis and the counterregulatory hormones cortisol and glucagon did not change. CONCLUSIONS: Despite improved PICU outcome, IIT did not counteract the catabolic state of critical illness. Suppression of portal insulin may have resulted in lower bioavailable IGF-I.

Oxidative stress after antenatal betamethasone: acute downregulation of glutathione peroxidase-3.

BACKGROUND: Human and experimental data show that antenatal exposure to glucocorticoids (GC) temporarily reduces fetal well-being and impairs the fetal response to hypoxemia. AIMS: We tested the hypothesis that antenatal betamethasone provokes transient oxidative stress, which may be triggered directly by the GC or indirectly by metabolic signals such as increased glucose and free fatty acid (FFA) concentrations. STUDY DESIGN: Prospective (single center, 18 months) cohort study in newborns <34 weeks gestational age at birth. METHODS: We studied 105 newborns and measured oxidative damage to lipids [malondialdehyde (MDA)] and proteins (protein carbonyls), as well as glutathione peroxidase-3 (GPx3), an important antioxidant enzyme, in umbilical vein (UV) plasma. In addition, we measured umbilical artery and UV blood gases, and metabolic indices (plasma glucose, FFA and insulin) in UV. RESULTS: MDA but not protein carbonyl concentrations was inversely related to time elapsed since the first or last betamethasone administration (p=0.006); MDA remained elevated by 69-96% for at least 72 h after the last betamethasone. By contrast, GPx3 concentrations were repressed in newborns who received betamethasone < or =24h before birth. GPx3 and MDA concentrations were correlated (r=-0.38, p<0.001). Labor, GA, sex, size at birth, blood gases or metabolic indices did not explain the effects of betamethasone on MDA and GPx3. CONCLUSIONS: Antenatal GC elicit a rapid suppression of the GPx3 antioxidant defense system which may contribute to a longer-lasting but also transient rise in lipid oxidative damage.

Duodenal calcium absorption in dexamethasone-treated mice: functional and molecular aspects.

Reduced intestinal calcium absorption may be part of the pathogenesis of glucocorticoid-induced osteoporosis. 1,25(OH)2D3 is the major regulator of the expression of the active duodenal calcium absorption genes: TRPV6 (influx), calbindin-D9K (intracellular transfer) and PMCA1b (extrusion). We investigated the influence of dexamethasone (5 days: 2 mg/kg bw) on calcium absorption in vivo and on the expression of intestinal and renal calcium transporters in calcium-deprived mice. Total and free 1,25(OH)2D3-concentrations were halved, in line with decreased 25(OH)D3-1-alpha-hydroxylase and increased 24-hydroxylase expression. Nevertheless, no difference in duodenal or renal calcium transporter expression pattern could be detected between vehicle and dexamethasone-treated mice. Accordingly, dexamethasone did not affect in vivo calcium absorption. By contrast, increased calcemia and collagen C-terminal telopeptide levels reflected increased bone resorption. Decreased osteocalcin levels suggested impaired bone formation. Hence, short-term glucocorticoid excess in young animals affected bone metabolism without detectable changes in intestinal or renal calcium handling.