Impaired activity of the extraneuronal monoamine transporter system known as uptake-2 in Orct3/Slc22a3-deficient mice.

Two uptake systems that control the extracellular concentrations of released monoamine neurotransmitters such as noradrenaline and adrenaline have been described. Uptake-1 is present at presynaptic nerve endings, whereas uptake-2 is extraneuronal and has been identified in myocardium and vascular and nonvascular smooth muscle cells. The gene encoding the uptake-2 transporter has recently been identified in humans (EMT), rats (OCT3), and mice (Orct3/Slc22a3). To generate an in vivo model for uptake-2, we have inactivated the mouse Orct3 gene. Homozygous mutant mice are viable and fertile with no obvious physiological defect and also show no significant imbalance of noradrenaline or dopamine. However, Orct3-null mice show an impaired uptake-2 activity as measured by accumulation of intravenously administered [(3)H]MPP(+) (1-methyl-4-phenylpyridinium). A 72% reduction in MPP(+) levels was measured in hearts of both male and female Orct3 mutant mice. No significant differences between wild-type and mutant mice were found in any other adult organ or in plasma. When [(3)H]MPP(+) was injected into pregnant females, a threefold-reduced MPP(+) accumulation was observed in homozygous mutant embryos but not in their placentas or amniotic fluid. These data show that Orct3 is the principal component for uptake-2 function in the adult heart and identify the placenta as a novel site of action of uptake-2 that acts at the fetoplacental interface.

Changes in membrane lipid composition of human erythrocytes after dietary supplementation of (n-3) polyunsaturated fatty acids. Maintenance of membrane fluidity.

The effect of dietary (n-3) polyunsaturated fatty acids on erythrocyte membrane lipid composition, fluidity, and flexibility was studied in seven healthy subjects. An eight weeks daily supplementation of 3 g of the (n-3) fatty acids eicosapentaenoic and docosahexaenoic acid resulted in an increased unsaturation of erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE). This change was accompanied by a slight decrease in PC and PE content (P less than 0.05) and an increase in sphingomyelin content (P less than 0.01). The erythrocyte membrane fluidity, measured with electron spin resonance of intact erythrocytes and with fluorescence polarization of erythrocyte ghosts did not change. No change was seen in the viscosity of erythrocyte suspensions of haematocrit = 0.80, measured at various shear rates. The supplementation caused a 42% decrease in plasma triacylglycerol levels. We suggest that the change in the erythrocyte membrane fatty acid composition induced by the dietary supplementation of (n-3) fatty acids might be counteracted by a change in the phospholipid class distribution, resulting in overall maintenance of membrane fluidity.

A patient with adrenocortical carcinoma: characterization of its biological activity and drug resistance profile.

We describe a patient with a metastasized adrenocortical cancer who exhibited excessive production of both glucocorticoids and mineralocorticoids combined with suppressed androgen production. Unusual steroid metabolites found in the patient's urine have not been described previously in association with this tumor type. Investigation of the multidrug resistance phenotype in single-cell suspensions of the tumor revealed low expression of multidrug resistance protein but high expression of P-glycoprotein (Pgp) and lung resistance-related protein. Functional Pgp in these tumor cells was shown by the modulatory effect of PSC833 on daunorubicin accumulation. Mitotane, at a concentration achieved in this patient's plasma, completely reversed the Pgp-related resistance both in the Pgp-overexpressing KB8-5 cell line and in the patient's tumor cells. On the basis of these in vitro results, the patient was treated with a combination of multidrug resistance drugs (doxorubicin, vincristine, and etoposide) plus mitotane as a Pgp modulator. This treatment was ineffective, however. A chemosensitivity assay demonstrated that the tumor cells were highly resistant to the drugs used. The adrenocortical cancer cells expressed mutant p53, and no evidence for induction of apoptosis by these drugs was found.

Nighttime insulin kinetics and glycemic control in type 1 diabetes patients following administration of an intermediate-acting lispro preparation.

OBJECTIVE: To determine insulin kinetics and overnight glycemic control after bedtime administration of a new intermediate-acting insulin preparation called neutral protamine lispro (NPL). RESEARCH DESIGN AND METHODS: We studied 12 patients with well-controlled type 1 diabetes. The study had a double-blind, randomized, crossover design. After a lead-in period of 10-14 days two experiments were carried out with an interval of 2-7 days. During these experiments overnight insulin kinetics and fasting blood glucose levels were studied after evening administration of NPH insulin and NPL. Blood glucose levels < 3.8 mmol/l were treated by means of a variable infusion of a 20% glucose solution. RESULTS: A trend toward a shorter time to peak insulin concentration was observed after administration of NPL (P = 0.07). No differences between NPH and NPL were detected in the total area under the curve (AUC) for insulin, in insulin levels before breakfast, or in glucose levels before breakfast (P = 0.5, 0.6, and 0.4, respectively). CONCLUSIONS: We detected no major differences between NPH and NPL in the total AUC for insulin, prebreakfast glucose levels, or prebreakfast insulin levels. Therefore, we conclude that NPH and NPL are equally effective in controlling overnight glycemia.

Optimized basal-bolus therapy using a fixed mixture of 75% lispro and 25% NPL insulin in type 1 diabetes patients: no favorable effects on glycemic control, physiological responses to hypoglycemia, well-being, or treatment satisfaction.

OBJECTIVE: To investigate the effects of a multiple injection regimen with a mixture of 75% lispro and 25% intermediate-acting insulin (lispro high mixture [HM]) before meals on glycemic control, physiological responses to hypoglycemia, well-being, and treatment satisfaction. RESEARCH DESIGN AND METHODS: We studied 35 type 1 diabetes patients. After an 8- to 10-week lead-in period, patients were randomized to HM or human regular insulin therapy for 12-14 weeks. During the lead-in and treatment periods, HbA1c levels and hypoglycemic frequencies were measured, and patients completed the Well-Being Questionnaire and the Diabetes Treatment Satisfaction Questionnaire. In 19 patients, responses to hypoglycemia were tested during stepped euglycemic-hypoglycemic clamps. RESULTS: HM treatment improved postprandial glycemia but had no effect on HbA1c, frequency of hypoglycemia, well-being, or treatment satisfaction. During experimental hypoglycemia, HM therapy was associated with a slightly lower total adrenaline response and a higher autonomic symptom threshold (i.e., the autonomic symptom response occurred at a lower blood glucose level) than human regular insulin therapy. We speculate that this effect resulted from an accumulation of insulin during the night. CONCLUSIONS: Multiple injection therapy with HM rather than human regular insulin before meals does not offer advantages regarding glycemic control, frequency of hypoglycemia, well-being, or treatment satisfaction. In addition, this regimen causes an attenuation of the adrenaline and autonomic symptom responses to hypoglycemia.

Effects of sorbinil treatment on erythrocytes and platelets of persons with diabetes.

Thirty-three diabetic subjects were given the aldose reductase inhibitor sorbinil (Pfizer, UK) for 3 wk. There was a significant fall in mean erythrocyte sorbitol concentration over this period. In all subjects erythrocyte sorbitol concentrations after treatment were within or below the range found in normal subjects. No changes in erythrocyte 2,3-diphosphoglycerate (2,3-DPG) or myo-inositol concentrations, plasma beta-thromboglobulin (beta-TG) concentration, or P50--a measure of the oxygen affinity of hemoglobin--were observed. There was a high incidence of adverse reactions to the drug.

Determinants of bone mineral density in older men and women: body composition as mediator.

This study aimed to assess the relative importance of several determinants of bone mineral density (BMD) and to examine to what extent these potential determinants influence total hip BMD through body composition. The study population consisted of 522 participants (264 women and 258 men) of the Longitudinal Aging Study Amsterdam (LASA), aged 65 years and over, and living in Amsterdam and its vicinity. BMD of the total hip was measured using dual-energy X-ray absorptiometry (DXA). Potential determinants of BMD were age, weight change since age 25 years, lifestyle factors, chronic diseases, medication use, and hormonal factors. Potential mediators between the possible determinants and BMD were two measures of body composition: fat mass (FM) and appendicular muscle mass (AMM). Multiple regression analyses including all potential determinants in one model without body composition identified age, weight change, walking activity, and sex hormone-binding globulin (SHBG) as independent determinants for total hip BMD in women. In men, current smoking, participation in sports, and parathyroid hormone (PTH) concentration were independently associated with total hip BMD. When total hip BMD was regressed on the potential determinants and each measure of body composition, it appeared that FM, and to a lesser extent, muscle mass (MM), were independently related to BMD. In women, adjustment for FM reduced the strength of the associations of weight change, walking activity, and SHBG with total hip BMD. Adjustments for MM did not influence the associations between the determinants and BMD. In men, neither FM nor MM appeared to play a mediating role between the determinants and BMD. It can be concluded that (1) FM and MM are strong independent determinants of total hip BMD and that (2) FM possibly plays a mediating role in the association of weight change, walking activity, and SHBG with total hip BMD in women.

Vitamin D status and sex hormone binding globulin: determinants of bone turnover and bone mineral density in elderly women.

To examine the relation of the vitamin D status and the remaining estrogen activity with bone turnover and bone mineral density (BMD) in elderly women, BMD was measured at both hips using dual-energy X-ray absorptiometry and at the distal radius using single photon absorptiometry, in 330 healthy women aged 70 and over. Vitamin D metabolites, sex hormone binding globulin (SHBG), PTH(1-84), osteocalcin, alkaline phosphatase, and hydroxyproline and calcium excretion in 2 h fasting urine were measured. Multiple linear regression was used to adjust for potential confounders. In 65% of the women, serum 25(OH)D was below 30 nmol/l. Only values below a threshold for 25(OH)D were negatively related to serum PTH(1-84) (p = 0.02, threshold at 25 nmol/l) and to osteocalcin levels (p = 0.04, threshold at 30 nmol/l). BMD of the femoral neck and trochanter was positively related to serum 25(OH)D (left neck p = 0.001) with thresholds at 30 nmol/l whereas the distal radius was not (p = 0.32). Serum PTH was negatively related to BMD at all measurement sites (all p < 0.001). Serum SHBG, an inverse measure of estrogen activity, was positively related to osteocalcin levels (p = 0.004) and the urinary hydroxyproline/creatinine ratio (p = 0.002) and negatively related to the BMD of the trochanter (left trochanter p = 0.02) and the distal radius (p = 0.001). We conclude that in elderly women, serum 25(OH)D levels below 30 nmol/l are associated with secondary hyperparathyroidism and increased bone turnover. SHBG is positively related to bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultraviolet irradiation corrects vitamin D deficiency and suppresses secondary hyperparathyroidism in the elderly.

The objective of this study was to compare the effect of ultraviolet radiation (UV) and oral vitamin D3 on the vitamin D status and parathyroid hormone (PTH) concentration in elderly nursing home patients. The design of the study was a randomized clinical trial. The setting was a psychogeriatric nursing home. Subjects included 45 female psychogeriatric patients with a mean age of 85 years. Exclusion criteria were going outdoors more than once a week and the presence of actinic or cancer skin lesions. Intervention was random allocation of UV-B irradiation at half the minimal erythemal dose of the lower back, three times per week during 12 weeks (UV-B), or oral vitamin D3 400 IU/day during 12 weeks (VIT-D), or no treatment (CONTR). Main outcome measures were change in fasting serum levels of vitamin D metabolites at 0, 2, 4, 8, and 12 weeks in the treatment groups, compared with the control group. PTH(1-84) was measured at 0 and 12 weeks. Baseline serum 25-hydroxyvitamin D (25(OH)D) was lower than 30 nmol/l in 95% of the participants. It increased to a median value of around 60 nmol/l after 12 weeks both in the UV-B and VIT-D groups, whereas there was no change in the CONTR group. Serum 1,25-dihydroxyvitamin D increased significantly in the UV-B group. Serum calcium increased significantly in both treatment groups. Serum PTH decreased more than 30% in both treatment groups (p < 0.001), whereas there was no significant change in the control group. Irradiation with UV-B in the very elderly for a few minutes per day leads to adequate improvement of the vitamin D status. It is as effective as oral vitamin D3 in increasing serum 25(OH)D and suppressing secondary hyperparathyroidism.

Intestinal calcium absorption and bone metabolism in young adult men with childhood-onset growth hormone deficiency.

Suboptimal growth hormone (GH) replacement therapy during childhood is a major cause of osteopenia in young adults with childhood-onset GH deficiency (CO-GHD). This is primarily attributed to reduced bone formation in childhood. It is currently not known whether GHD also has adverse effects on bone metabolism in adult life. To examine the impact of GHD on calcium and bone metabolism in adults, we evaluated 50 men with CO pituitary failure at a mean age of 28.2+/-4.5 years, i.e., 8.8+/-4.1 years after the discontinuation of previous GH treatment for short stature. Thirty-three patients had multiple pituitary hormone deficiencies (MPHD) for which they received conventional replacement therapy, seventeen patients had isolated GHD (IGHD), and forty-nine age-matched men served as controls. Intestinal calcium absorption, serum calcium concentration, serum phosphate levels, and renal calcium and phosphate excretion were normal in IGHD and MPHD patients. IGHD patients had marginally elevated serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen (ICTP: 5.0+/-1.2 vs. 4.2+/-1.2 microg/l, p < 0.05), but other indices of bone turnover were normal. In contrast, MPHD patients had reduced levels of the carboxy-terminal propeptide of type I procollagen (PICP: 137+/-76 vs. 179+/-72 microg/l, p < 0.01), elevated serum ICTP levels (6.0+/-3.8 vs. 4.2+/-1.2 microg/l, p < 0.001), and reduced serum 1,25-dihydroxyvitamin D levels (55.1+/-16.7 vs. 73.0+/-23.0 pmol/l, p < 0.001). Multivariate regression analysis showed that the serum levels of bone resorption and bone formation markers in MPHD patients were correlated with the hydrocortisone, thyroxine, and testosterone replacement doses. There was no relationship with serum insulin-like growth factor I concentration. Panhypopituitary adults receiving conventional hormone replacement therapy are at risk to develop osteopenia either caused by reduced bone formation or by increased bone resorption activity. Predominantly, these abnormalities result from nonoptimal thyroid, gonadal, or adrenal hormone replacement therapy. GHD is not an important factor. In adults, GHD does not adversely affect intestinal calcium absorption or bone formation activity. Bone resorption activity may be slightly higher than normal, but the abnormality is too small to expect substantial bone loss as a consequence of GHD.

Effects of the selective estrogen receptor modulator, raloxifene, on the somatotropic axis and insulin-glucose homeostasis.

Raloxifene is the first selective estrogen receptor modulator registered for the prevention and treatment of postmenopausal osteoporosis. In addition to direct effects on bone cells, estrogen and raloxifene may act indirectly via changes in hormonal homeostasis. However, the menopause-related decrease in serum insulin-like growth factor I (IGF-I) and the increase in insulin or glucose are not always reversed by estrogen replacement. Especially orally administered estrogen was reported to decrease serum IGF-I levels. Understanding the effects of estrogens and raloxifene on the GH-IGF axis and insulin-glucose homeostasis are important because of their link to bone metabolism and cardiovascular health. We investigated the effects of raloxifene on the GH-IGF-I axis and insulin-glucose homeostasis in a cross-sectional study in the third year of the Multiple Outcomes of Raloxifene Evaluation trial, a double blind, placebo-controlled, prospective study in postmenopausal women with osteoporosis (T-score of -2.5 or less or at least two moderate vertebral fractures). Patients with diabetes mellitus were excluded from this additional study. A fasting blood sample was obtained (0 h), and women received an sc injection of 0.05 mg recombinant human GH (Humatrope)/kg BW. The second blood sample was obtained 24 h later (24 h). GH, IGF-I, IGF-binding protein-3 (IGFBP-3), insulin, and glucose were measured. Group characteristics were tested by nonparametric ANOVA. The dose-response to raloxifene was tested by linear regression models, with age and body mass as covariates. Seven women were taking placebo, 16 were taking raloxifene (60 mg/day), and 9 were taking raloxifene (120 mg/day). Patients from the 60 mg raloxifene group were the oldest (mean +/- SD, 64.4 +/- 4.2 vs. 69.3 +/- 6.9 and 63.3 +/- 5.9 yr for placebo, 60 mg/day raloxifene, and 120 mg/day raloxifene, respectively; P = 0.05). Compared with placebo users, patients taking raloxifene had higher body mass index (24.7 +/- 1.7 vs. 25.0 +/- 3.1 and 28.8 +/- 5.8 kg/m(2); P = 0.03). At 0 h, raloxifene use was associated with lower IGF-I/IGFBP-3 ratio (4.3 +/- 0.7 vs. 2.9 +/- 0.7 and 3.0 +/- 0.7 nmol/mg; P = 0.001) and insulin/glucose ratio (13.7 +/- 5.2 vs. 11.9 +/- 5.9 and 9.5 +/- 2.3 pmol/mmol; P = 0.04). Similarly, raloxifene use was associated with lower IGF-I/IGFBP-3 and insulin/glucose ratios at 24 h (P = 0.01 and 0.07). Glucose, GH, and IGFBP-3 levels were similar among the groups (0.12 < P < 0.67). In conclusion, raloxifene use is associated with decreased serum IGF levels and insulin/glucose ratio before and 24 h after one rhGH injection in nondiabetic postmenopausal women with osteoporosis. Therefore, raloxifene may decrease liver sensitivity to GH. Other explanations are increased clearance or increased tissue sensitivity to IGF-I or insulin. The raloxifene-induced increases in bone mineral density do not appear to be mediated by reversing the age- and menopause-related decreases in IGF-I levels. The results of this small cross-sectional study need confirmation by longitudinal studies.

The effect of one-year cross-sex hormonal treatment on bone metabolism and serum insulin-like growth factor-1 in transsexuals.

The effects of treatment with estrogens and antiandrogens in male to female (M-->F) transsexuals and androgens in female to male (F-->M) transsexuals on their respective bone metabolism, bone mineral density (BMD), serum insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) levels were investigated. BMD and variables of bone turnover in serum were measured at baseline and after 3 months (except for BMD) and 1 yr of treatment in 56 M-->F and 35 F-->M transsexuals. Serum IGF-I, IGFBP-3, and propeptide of type I procollagen (P1CP) were measured at baseline and after 1 yr of treatment in 10 M-->F and 10 F-->M transsexuals. In M-->F, BMD increased significantly. Bone turnover decreased, as shown by a significant decline in levels of osteocalcin, alkaline phosphatase, P1CP, and fasting urinary calcium/creatinine and hydroxyproline/creatinine ratios. Serum IGF-I levels decreased significantly without significant changes in IGFBP-3 levels. In F-->M, BMD did not change. Bone formation increased, as suggested by an increase in alkaline phosphatase and a borderline increase in P1CP values. IGF-I levels increased significantly, whereas no significant changes were seen in IGFBP-3 levels. We conclude that in males, estrogens (in combination with antiandrogens) decrease bone turnover, with a subsequent increase in BMD and a decrease in serum IGF-I. In females, testosterone administration increases bone formation, but this is not reflected in an increased BMD, whereas serum IGF-I increases.

The optimal growth hormone replacement dose in adults, derived from bioimpedance analysis.

The prevalence of clinical signs and symptoms related to fluid retention is high in most studies evaluating the efficacy of GH treatment in GH-deficient (GHD) adults. This may be a consequence of supraphysiological GH replacement. To examine whether fluid retention is a dose-related phenomenon, we evaluated the impact of various GH substitution doses on body fluid status in 46 GHD men participating in a 1-yr, double blind, and placebo-controlled study. The patients were randomized to receive either placebo (n = 13) or GH in a dose of 1 (n = 11), 2 (n = 10), or 3 (n = 12) IU/m2.day, respectively. Treatment was started at one third of the predetermined dose and was subsequently increased by another third every month until the maintenance dose was reached. Tissue hydration was assessed by means of electrical impedance measurements. Normal values were obtained from 128 age- and sex-matched controls. In the untreated GHD state, whole body resistance was abnormally high (observed, 642 +/- 82 omega; predicted, 550 +/- 31 omega; P < 0.001). This was mainly caused by an increase in specific resistance of the lean body as a consequence of a reduction in extracellular water (ECW). The first month of GH treatment was associated with a sharp decline in electrical resistance that was attributed to an increase in ECW. Whole body resistance reached its nadir after 3 months of treatment (517 +/- 72 omega, i.e. 19.6 +/- 6.5% lower than before treatment; P < 0.001) and did not change significantly thereafter. The GH-induced changes in body resistance were dose dependent. A significant decrease was observed with a dose as low as 0.33 IU/m2.day (P < 0.005). However, whole body resistance remained higher than normal in patients receiving less than 0.67 IU/m2.day (P = 0.05). Abnormally low resistance values, indicative of overhydration, were observed in patients receiving doses equal to or higher than 2 IU/m2.day (P < 0.005). Regression analysis of the pooled data showed that GH replacement in a dose of 1.10 IU/m2.day (95% confidence interval, 0.85-1.45 IU/m2.day) resulted in a normalization of whole body resistance. In conclusion, GH replacement therapy in adults rapidly corrects the preexisting deficit in ECW. This rehydration process is dose dependent and may result in a substantial weight gain.(ABSTRACT TRUNCATED AT 400 WORDS)

Monitoring of growth hormone replacement therapy in adults, based on measurement of serum markers.

The optimal dose for GH replacement therapy in GH-deficient (GHD) adults is not known, nor is there a consensus as to which method is the most appropriate for the monitoring of treatment. To establish a general guideline for GH replacement therapy in adults, we evaluated the relationship between the administered GH dose and the achieved serum levels of three GH-dependent serum markers. Serum levels of insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3), and the acid-labile subunit (ALS) were measured in 46 GHD men participating in a 1-yr, double blind, and placebo-controlled dose-response study. The doses of recombinant human GH ranged from 0.33-3.0 IU/m(2)-day. During GH treatment, dose reduction was necessary because of side-effects in 18 of 46 patients, i.e. in 18% of the patients receiving a maintenance dose of 1 IU/M(2)-day, in 35% of the patients receiving a dose of 2 IU/m(2)-day, and in 67% of the patients receiving a dose of 3 IU/M(2)-day. In the untreated state, serum levels of all three markers were below the normal range in 90% of the patients. The rise in serum marker concentrations during the first month of treatment was dose dependent. Significant increases in IGF-I, IGFBP-3, and ALS levels were observed with a dose as low as 0.33 IU/M(2)-day. The minimal GH dose required for normalization of the serum IGF-I concentration was 0.66 IU/M(2)-day, and it was 1.0 IU/M(2)-day for ALS and IGFBP-3. In patients receiving 2.0 IU/M(2)-day, the mean serum IGF-I concentration rose to an abnormally high level, whereas at this dose, the mean IGFBP-3 and ALS levels were not different from normal. The lower sensitivity of IGFBP-3 and ALS to GH doses in the high range was also apparent during long term treatment. The number of patients who developed IGFBP-3 or ALS levels that exceeded the upper normal limit was substantially smaller than the number of patients with elevated IGF-I concentrations (2, 8, and 19 of 46 patients, respectively). In conclusion, serum IGF-I appears to be the preferred biochemical marker for the detection of GH excess in adults receiving GH replacement therapy, because it is more sensitive than IGFBP-3 and ALS to GH doses in the high range. If normalization of the serum IGF-I concentration is taken as the criterion for optimal GH replacement therapy, the predicted optimal GH dose for GHD men 20 - 40 yr old is 1.4 IU/M(2)-day, and the 95% confidence interval is 1.2-1.6 IU/M(2)-day.

The relationship between thyrotropin and low density lipoprotein cholesterol is modified by insulin sensitivity in healthy euthyroid subjects.

High levels of TSH are associated with an increased cardiovascular risk. Many cardiovascular risk factors cluster within the insulin resistance syndrome. It is not known whether levels of TSH cluster as well. We conducted this research to test the hypothesis that TSH, insulin sensitivity, and levels of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) are interdependent in euthyroid subjects. Levels of TSH, free thyroid hormone, and serum lipids were measured in fasting serum samples taken before performance of a hyperinsulinemic euglycemic clamp to assess insulin sensitivity in 46 healthy euthyroid subjects with a mean TSH of 1.8 +/- 0.7 mU/L. Significant age- and sex-adjusted partial correlations of TSH with LDL-C (r = 0.48; P < 0.01) and HDL-C (r = -0.36; P < 0.05) were observed. TSH was not significantly correlated with insulin sensitivity or fasting triglyceride concentrations. In line with these results, we found the associations of TSH with LDL-C and HDL-C to be independent of insulin sensitivity. However, we observed significant effect-modification of the association of TSH with LDL-C by insulin sensitivity (P = 0.02). This effect-modification implies a range of associations of TSH with LDL-C that varies from absent in insulin-sensitive subjects to strongly positive in insulin-resistant subjects. We conclude that the increased cardiovascular risk associated with subclinical hypothyroidism seems to extend itself into the normal range of thyroid function. Importantly, the effect-modification of the association of TSH with LDL-C by insulin sensitivity suggests that insulin-resistant subjects are most susceptible to this increased risk.

Increased levels and pulsatility of follicle-stimulating hormone in mothers of hereditary dizygotic twins.

According to the endocrine model of hereditary dizygotic twinning, high FSH is responsible for multiple ovulation and pregnancy. Our study explored the underlying neuroendocrine causes. In a prospective clinical study, we compared the third day of menses parameters of episodic secretion of LH and FSH, the pituitary response to LHRH, plasma estradiol, and dimeric inhibin A and B in 16 regularly menstruating and 9 postmenopausal mothers of dizygotic twins with a family history of twinning and 14 premenopausal and 9 postmenopausal controls. Seven of 16 premenopausal mothers of twins had abnormally high FSH levels of more than 10 IU/L compared with 1/14 in controls (P = 0.024). In the premenopausal mothers of twins, mean FSH concentrations (P = 0.025) and FSH pulse frequency (P = 0.003) were significantly elevated, whereas FSH pulse amplitude and FSH response to LHRH were unaltered. For LH, neither the secretory parameters nor the response to LHRH was different. There were no differences between estradiol and inhibin A and B levels. Postmenopausal mothers of twin and controls did not differ with respect to the secretory pattern of LH and FSH. We conclude that under equal ovarian feedback conditions, premenopausal mothers of a dizygotic twin have hyper stimulation by endogenous FSH caused by neuroendocrine, hypothalamic, or pituitary mechanisms. This is the result of altered responsiveness to ovarian feedback and/or pituitary or suprapituitary, non-LHRH-like mechanisms that stimulate pulsatile FSH.

Fetal growth and the function of the adrenal cortex in preterm infants.

Small for gestational age preterm infants have a higher risk of neonatal morbidity compared to appropriate for gestational age preterm infants. A diminished adrenal response to stress may be involved in the higher postnatal morbidity. The adrenal cortex response in relation to fetal growth was studied by ACTH stimulation tests in 43 preterm infants (born < or = 32 wk). The cortisol and 17-hydroxyprogesterone (17-OHP) responses to 1 microg/kg ACTH were analyzed in relation to birth weight SD scores (BW-SDS) corrected for gestational age, gender, and parity. BW-SDS was significantly associated with the cortisol and 17-OHP response. Infants with the lowest BW-SDS had the lowest cortisol levels after stimulation. No effect of size at birth was found on the ratio between cortisol and 17-OHP. In addition, basal cortisone levels in a single blood sample were higher in infants with the lowest BW-SDS than in infants with higher BW-SDS, but the ratio between cortisol and cortisone was comparable in the two groups. We conclude that the response of cortisol and 17-OHP to ACTH stimulation in preterm infants is related to fetal growth. The lack of influence of fetal growth on the ratio between cortisol and 17-OHP after ACTH stimulation suggests that the activities of 21- and 11 beta-hydroxylase are not affected. The lower adrenal response to stimulation may be important in neonatal morbidity and possibly the development of disease in later life in growth-restricted preterm infants.

Omega-3 fatty acids in adipose tissue of obese patients with non-insulin-dependent diabetes mellitus reflect long-term dietary intake of eicosapentaenoic and docosahexaenoic acid.

We examined the relationship between long-term dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the relative content of these fatty acids in adipose tissue triglycerides from 53 obese Dutch subjects--19 men and 34 women--with non-insulin-dependent diabetes mellitus (NIDDM). Adipose tissue fatty acid profiles analyzed in three samples taken from each subject at 1-y intervals showed no within-subject differences for EPA and DHA. Dietary intake was estimated from 12 3-d dietary records made over 2 y at 2-mo intervals. EPA and DHA intakes showed high within-subject variation. Correlation coefficients (Spearman) between the dietary intake of EPA (% of total fat) and EPA in adipose tissue (% of total fatty acids) were 0.76 for men and 0.57 for women. For DHA these coefficients were 0.75 for men and 0.48 for women. We conclude that the analysis of fatty acids in one adipose tissue biopsy provides information on long-term EPA and DHA intakes in obese subjects with NIDDM, and can replace otherwise necessarily frequent diet analyses over a long period.

Dose-response effects of fish-oil supplementation in healthy volunteers.

We performed a randomized, controlled study on the dose-response effects of daily supplementation of 1.5, 3, and 6 g of the marine fatty acids eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) as their ethyl esters for 12 wk in 45 healthy normotriglyceridemic male volunteers. Significant dose-related increases of the n-3 fatty acids 20:5, 22:5, and 22:6 in plasma phospholipids (p less than 0.0001) were found, corresponding roughly to decreases of the n-6 fatty acids 18:2 and 20:4 (p less than 0.001). Serum triglycerides and HDL3-cholesterol concentrations showed a dose-dependent reduction (p less than 0.05) and HDL2 cholesterol increased (p less than 0.05). Results for 3 and 6 g n-3 fatty acids were similar. No dose-dependent effects were observed in the VLDL-, LDL-, and total HDL-cholesterol subfractions; blood pressure; bleeding time; erythrocyte deformability; or capacity of polymorphonuclear leukocytes to kill Staphylococcus aureus. This study indicates that 3 g n-3 ethyl ester fatty acids appears to be the appropriate supplementation dose in humans, at least regarding lipid-profile changes and the ability to incorporate such fatty acids in the plasma phospholipids.

Linoleic-acid-enriched diet: long-term effects on serum lipoprotein and apolipoprotein concentrations and insulin sensitivity in noninsulin-dependent diabetic patients.

Long-term (30 wk) effects on serum lipoproteins and insulin sensitivity of two diets, one with a low polyunsaturated to saturated fat ratio (P:S 0.3) and one with a P:S of 1.0, were compared in 14 patients with noninsulin-dependent diabetes mellitus (NIDDM) in a crossover study. Total and LDL-cholesterol levels declined by 7.6% (p less than 0.01) and 9.8% (p less than 0.01), respectively, during the high P:S diet. VLDL-, HDL2-, and HDL3-cholesterol; triacylglycerol; and apolipoprotein A1, A2, and B levels were not affected by the change in P:S. Despite a modest increase of insulin-mediated glucose disposal at physiologic insulinemia during the high P:S diet, no influence was seen on glycemic control, and on blood glucose, plasma insulin, and C peptide responses to mixed meals. In conclusion, a linoleic-enriched diet in patients with NIDD causes a less atherogenic lipoprotein profile but does not influence glycemic control and carbohydrate tolerance.