Factors associated with serum levels of estradiol and sex hormone-binding globulin among premenopausal Japanese women

We measured serum levels of estradiol (E(2)) and sex hormone-binding globulin (SHBG) among 50 healthy premenopausal Japanese women in 1994 in Gifu, Japan, to investigate the relationships between potential risk factors for breast cancer and hormone levels. Using a self-administered questionnaire, we collected data on body size, physical activity, and previous disease history, as well as menstrual and reproductive histories of the woman and her mother. Blood samples were drawn from each subject on the 11th and 22nd days of her menstrual cycle. Higher serum E(2) levels were observed for women with shorter menstrual cycles. Age as well as cycle length were included in the regression models to determine the associations between hormone levels and study variables. Body mass index (BMI) was inversely related to SHBG level measured at the 11th day of the cycle, after adjusting for age and cycle length (r = -0.33; p = 0. 03). Women born in spring/summer had higher levels of E(2) on the 22nd day (p = 0.07) and higher levels of SHBG on both the 11th and 22nd days of the cycle (p = 0.01 and p = 0.06, respectively) than those born in other seasons. Physical activity at 13-15 years of age was inversely related to E(2) level on the 11th day of the cycle after controlling for age, cycle length, BMI, and birth month (r = -0.35; p = 0.04).     

Quantitative genetics of serum sex hormone-binding globulin levels in participants in the San Antonio Family Heart Study

Sex hormone-binding globulin (SHBG) is a steroid-binding plasma protein with a high affinity for testosterone that has been inversely associated with cardiovascular disease risk in many populations. SHBG may also act as a receptor in some tissues. Although the function of SHBG is relatively well understood, comparatively little is known about genetic factors contributing to the normal variation of serum SHBG levels. We estimated the heritability (h2) of serum SHBG levels in 717 related Mexican-Americans participating in the San Antonio Family Heart Study (SAFHS). We found a significant heritability (h2 = 0.31, P < .0001) for serum SHBG levels; age, exogenous hormones, smoking status, diabetic status, and adiposity showed significant associations (P < .05) with mean levels of SHBG. Sex was associated with mean SHBG levels but not with genetic or environmental variance in SHBG levels; heritability estimates were the same for males and females. These results indicate a significant genetic influence on SHBG in Mexican-Americans. Thus, SHBG may prove to be an important indicator of genetic risk for cardiovascular disease in this population, as well as others.     

Linoleic acid intake and susceptibility of very-low-density and low density lipoproteins to oxidation in men

Lipoprotein peroxidation is thought to play an important role in atherogenesis. In the Kuopio Atherosclerosis Prevention Study (KAPS) the intake of fat and fatty acids, the oxidation susceptibility of the plasma very-low-density + low-density lipoprotein (VLDL+LDL) fraction (by induction with copper or hemin and hydrogen peroxide), and concentrations of plasma antioxidants, serum lipids, and lipoproteins were measured in 393 men. In the multivariate-regression model dietary linoleic acid was the most important determinant of the maximal oxidation velocity for the hemin assay (standardized regression coefficient = 0.294, P<0.0001). In the copper assay the association of dietary linoleic acid and maximal oxidation velocity was second in order of strength (standardized regression coefficient = 0.324, P< 0.0001). We conclude that high linoleic acid intake is associated with increased oxidation susceptibility of atherogenic lipoproteins in men.     

Purification and characterization of the sex hormone-binding globulin in serum from Djungarian hamsters

A high-affinity sex hormone-binding globulin (SHBG) was purified from the serum of prepubertal Djungarian hamsters (Phodopus sungorus). A purification of more than 2000-fold with an overall yield of 23% was achieved without the use of androgen affinity chromatography. Two predominant variants (51 and 55 kDa) were resolved by denaturing polyacrylamide gel electrophoresis. Both variants participated in the binding of dihydrotestosterone (DHT) and had identical amino-terminal sequences. The sequences obtained for Djungarian hamster SHBG (dhSHBG) showed a high degree of identity with those of other mammals. The affinity of purified dhSHBG for DHT (2.5 x 10(9) M(-1) was similar to that measured in unfractionated serum. This protein was isolated as a dimer with a single calcium-dependent steroid-binding site and a major pI of 4.7. The described purification procedure yielded active dhSHBG from small volumes of prepubertal serum. These studies also provide the first direct structural evidence that a SHBG-like protein, not of testicular origin, is expressed by a rodent during prepubertal development.     

Effects of hormonal replacement therapy on plasma sex hormone-binding globulin, androgen and insulin-like growth factor-1 levels in postmenopausal women

Plasma sex hormone-binding globulin (SHBG) levels are important in the regulation of plasma free and albumin-bound androgens and estrogens. In postmenopausal women associated to the decrease of estrogen production, a decrease of plasma SHBG levels occurs. Hormone replacement therapy (HRT) in postmenopausal women modulates plasma SHBG levels, in relationship with the different regimens and routes of administration. The present study aimed to compare the effect of different HRT on plasma SHBG levels in relationship with the changes of plasma androgen [dehydroepiandrosterone sulphate (DHEAS), testosterone (T), androstenedione (A)] and insulin-like growth factor-1 (IGF-1) levels. In a retrospective study 443 postmenopausal women were studied and divided into 2 groups. The group 1 (n = 170) was subdivided in 4 groups of women as follows: A) treated with transdermal 17-beta estradiol + medroxyprogesterone acetate, B) treated with oral conjugated estrogens, C) treated with sequential HRT (estradiol valerate (EV) + norgestrel), and D) treated with a combined HRT (micronized estradiol (E2) + noretisterone acetate). Women of group 2 (n = 273) did not receive HRT and served as controls. All groups of women treated with different HRT showed plasma estradiol levels significantly higher than controls (p < 0.01), showing the highest values in women treated with oral HRT. Plasma SHBG levels were not significantly different between patients treated with transdermal 17-beta estradiol + medroxyprogesterone acetate and controls. On the other hand, all the groups of patients treated with oral conjugated estrogen with or without progestagens showed plasma SHBG levels significantly higher than controls (p < 0.01). Plasma SHBG levels were higher in the group treated with estrogen alone than in groups of women treated with sequential or combined HRT. Plasma DHEAS, T and A levels in patients treated with different HRT regimens were in the same range of levels as control women. Plasma IGF-1 levels were not significantly affected by the various HRT regimens and remained in the same range as controls. In conclusion, plasma SHBG levels increase following oral HRT while are not affected by transdermal HRT. Plasma IGF-1 and androgen levels are not influenced from oral or transdermal HRT.     

Testosterone treatment in men with erectile disorder and low levels of total testosterone in serum

Since decreased serum levels of testosterone (T) do not necessarily predict good outcome of testosterone treatment for erectile disorder, the purpose, of this study was to determine which men with erectile disorder and decreased serum levels might benefit from treatment. From a sample of 31 men (mean age = 39 years), 15 (48%) with erectile disorder and decreased serum levels of T responded well after 8 weeks of testosterone treatment (100 mg of testosterone propionate in the sustained-release form given im once a week). Good treatment outcome was associated with several variables, but only high levels of luteinizing hormone (LH) and low values of the T/LH (testosterone/LH) ratio consistently emerged as significant correlates and/or predictors of effective treatment. Levels of LH above 7.5 IU/L or the values of the T/LH ratio equal to or below 0.87 nmol/IU in patients with erectile disorder and decreased serum levels of T suggest that testosterone treatment may be effective.     

Growth response of adult germ cells to rat androgen-binding protein and human sex hormone-binding globulin

Androgen-binding protein (ABP) is produced by Sertoli cells depending on the development and the stage of the spermatogenic cycle. Germ cell proliferation is at its peak when ABP is at its peak and secreted towards the testicular basal compartment containing spermatogonia and premeiotic spermatocytes. Rat isolated adult germ cell DNA synthesis was studied in vitro in the presence of ABP with and without steroids and in the presence of pure or recombinant sex steroid hormone-binding globulin (SHBG) using thymidine incorporation. Results are: SHBG is able to promote DNA synthesis in the absence of cofactors. Testosterone reacted negatively to the stimulatory effect of SHBG. We conclude that ABP, the physiological steroid-binding protein, should be considered as a paracrine regulator of spermatogenic DNA synthesis in the adult rat.     

Annual rhythmic variations of follitropin, lutropin, testosterone and sex-hormone-binding globulin in men

Four distinct studies were carried out using two data sets of percutaneous epididymal sperm aspiration (PESA) and intracytoplasmic sperm injection (ICSI) procedures performed from March 1993 to January 1997. In study A, an analysis of 181 ICSI treatment cycles following PESA revealed a successful epididymal sperm retrieval rate of 83%. It confirmed that PESA is an effective sperm retrieval method and the associated ICSI pregnancy rate (35% per embryo transfer) compared favourably with that of other sperm retrieval methods. In study B, the relevance of a prior diagnostic PESA procedure was ascertained by comparing the sperm retrieval rates in two groups of patients having their first ICSI treatment cycle with spermatozoa retrieved through PESA. Group B1 (n = 50) had diagnostic PESA prior to the ICSI treatment cycle PESA procedure, unlike patients in group B2 (n = 64) who did not. The sperm retrieval rate in the treatment cycle procedure was not different at 90 and 82.8% for groups B1 and B2 respectively. However, the discontinuation of diagnostic PESA is fraught with problems including liability to medico-legal sanctions. In study C, analysis of 177 treatment cycles involving PESA and ICSI revealed a successful sperm retrieval rate by PESA of 82% in the first cycle, 93% in the second, 96% in the third and 100% in the fourth cycle. The same trend was evident when sperm retrieval was examined in relation to each of the epididymides. Retrieved spermatozoa were found to be motile in 67-100% of cases and the frequency of samples containing motile spermatozoa did not decrease with increase in the number of PESA attempts. These results show that PESA does not jeopardize future epididymal sperm retrieval. In study D, the outcome of treatment with ICSI using ejaculated spermatozoa (305 cycles) (group D1) was compared with that of ICSI using spermatozoa obtained through PESA (54 cycles) (group D2). The median age of women in the two groups of couples was similar (34 years). In group D1, 70% of metaphase II oocytes were fertilized compared with 61% in group D2 (P < 0.01). The cleavage rate and the median numbers of transferred and cryopreserved embryos were similar in both groups. There was no significant difference between the clinical pregnancy rates (33 and 42% in groups D1 and D2 respectively). Our results show that the outcome of PESA-ICSI treatment compares favourably with that of ICSI using ejaculated spermatozoa.     

High levels of interleukin-6 are associated with low tumor burden and low growth fraction in multiple myeloma

Interleukin-6 (IL-6) is a multifunctional cytokine postulated to play a central role as a growth factor for multiple myeloma (MM). We evaluated the spontaneous secretion of IL-6 in supernatants of Ficoll-Hypaque--enriched bone marrow (BM) cultures from 35 patients with MM. The levels of IL-6 were correlated with biological and clinical characteristics of the disease. High levels of IL-6 production defined a subgroup of patients with low tumor burden as determined by lower serum beta 2-microglobulin (B2M) (P = .02) and lower percentage of myeloma cells infiltrating the bone marrow (P = .003), higher synthetic rates of monoclonal protein (P = .006), and low proliferative compartments as measured by the percentage of Ki-67--positive myeloma cells. Patients with high proliferative fractions (Ki-67--positive myeloma cells > 20%) had significantly lower levels of IL-6 when compared with patients with low proliferative fractions (P = .005). Our findings do not support IL-6 as a major growth factor for MM, but demonstrate an association of high levels of IL-6 secretion with low tumor cell burden and low proliferative fraction.     

Transient triglyceridemia in healthy normolipidemic men increases cellular processing of large very low density lipoproteins by fibroblasts in vitro

Exaggerated and prolonged postprandial triglyceridemia is a characteristic of patients with precocious coronary heart disease. Although large very low density lipoprotein (VLDL) particles accumulate during alimentary lipemia, the biological properties of the postprandial VLDL remain unknown. In the present study, an intravenous infusion of a chylomicron-like emulsion was given to healthy normolipidemic men to examine the effects of transient triglyceridemia in vivo on compositional and cell biological characteristics of VLDL. The postinfusion large(Svedberg flotation rate (Sf) (60-400) VLDL was found to have increased capacity to inhibit low density lipoprotein (LDL) binding to the LDL-receptor and a greater ability to suppress the 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity of cultured fibroblasts compared to VLDL isolated from fasting plasma. These alterations in cellular interactions were accompanied by increases in the number of apolipoprotein (apo) E, C-I, and C-III molecules per large VLDL particle and loss of apoC-II, compositional changes similar to those observed after an oral fat load. The increase in number of apoE molecules per large VLDL particle correlated positively and significantly with the increase in the capacity of large VLDL to inhibit LDL binding to the LDL receptor (r = 0.76, P = 0.01, n = 10). In contrast, the composition of the small (Sf 20-60) VLDL particles did not change significantly, nor was the LDL receptor-mediated processing of these particles altered consistently. These observations indicate that large VLDL particles that accumulate during alimentary lipemia undergo compositional changes that render them more prone to cellular binding and uptake.     

Free testosterone levels, attentional control, and processing speed performance in aging men.

Psychometric measures of processing speed are strong predictors of cognitive functioning with aging; however, the neurobiological mechanisms underlying this association remain unclear. Recently, the authors reported a negative association between calculated free testosterone levels (cEFT) and processing speed in men aged between 50 and 70 years (Martin, Wittert, Burns, & McPherson, 2008). Ex-Gaussian decomposition of reaction time (RT) distributions allows for the robust estimation of skew in the distribution, which may reflect poorer attentional control. In a reanalysis of data from this previous study, the authors examined the associations between age, cEFT levels, and ex-Gaussian parameters derived from four RT tasks as predictors of cognitive functioning performance in 96 middle-to-older aged men. Results indicated that cEFT levels were significantly associated with increased skew in the RT distribution (i.e., the exponential portion) but not with the estimates derived from the Gaussian portion of the curve. Further, path analysis across the entire data set showed that this association was a strong predictor of processing speed performance. Taken together these results suggest that cEFT levels moderate cognitive functioning performance in males via attentional control processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased plasma HIV type 1 RNA levels are associated with low levels of non-MHC class I-restricted cytotoxicity

2329 subjects (blood donors and patients) from various areas of the Sultanate of Oman were investigated for the presence of HTLV-I antibody by as enzyme immunoassay (EIA) method. 10 subjects (0.4%), including 9/1586 blood donors (0.6%) and 1/165 patients with sexually transmitted diseases (0.6%), were found to be EIA seropositive with a regional variation in seroprevalence of 0-14%. 6/9 EIA seropositive samples from blood donors yielded 'indeterminate' results on Western immunoblot analysis (WBA). A much larger survey with additional confirmatory assays such as a radioimmunoprecipitation assay (RIPA), should provide a more conclusive picture of the prevalence of this retroviral infection in the Sultanate.     

The effects of oxidized low density lipoproteins on inducible mouse macrophage gene expression are gene and stimulus dependent

Oxidized LDL has been previously reported to suppress the expression of genes induced in mononuclear phagocytes by inflammatory stimuli. In this study we extend these findings to demonstrate that the suppressive effects of oxidized LDL vary depending upon the gene being monitored and the stimulus being used to induce or enhance its expression. The expression of a selection of LPS-inducible genes exhibited differential sensitivity to pretreatment with oxidized LDL. Furthermore, the ability of oxidized LDL to suppress gene expression varied markedly with the inducing stimulus used. TNF alpha and IP-10 mRNA expression induced by IFN gamma and IL-2 was markedly more sensitive to suppression by oxidized LDL than that induced by LPS. The cooperative effects of IFN gamma and LPS on the expression of the inducible nitric oxide synthase gene were suppressed by oxidized LDL while the antagonistic effect of IFN gamma on LPS-induced expression of the TNF receptor type II mRNA was not altered. The suppressive activity of LDL was acquired only after extensive oxidation and was localized in the extractable lipid component. These results suggest a potent and direct connection between the oxidative modification of LDL and the chronic inflammation seen in atherogenic lesions. Furthermore, the appreciable selectivity of oxidized LDL in mediating secondary control of cytokine gene expression demonstrates that the active material(s) is targeted to disrupt specific intracellular signaling pathways.     

Bone density, bone turnover, and hormone levels in men over age 75

BACKGROUND: Osteoporosis is a substantial problem in older men, with 25% of all hip fractures occurring in men. The mechanisms of bone loss in older men are unknown, but elevated parathyroid hormone (PTH) and diminished testosterone (T) levels are postulated as contributing factors. METHODS: We measured bone mineral density (BMD), sex hormones, bone turnover markers, and calcium regulating hormones in a group of community-living men over the age of 75. RESULTS: Thirty-five men (mean age 79; range 75-88 years) without disease or medication known to affect bone metabolism participated in the study. Whole body BMD was 1.21+/-.15 g/cm2; lumbar spine BMD (L1-L4) was 1.10+/-.15 g/cm2; femoral neck BMD was .77+/-.14 g/cm2; and trochanteric region was .71+/-.13 g/cm2. The femoral neck and trochanteric region values were more than 1 SD below the mean for adult men (age 25-33 years) in 28/35 and 15/35 men, respectively. Deoxypyridinoline levels were above the normal range for premenopausal women in 23% of the men; N-telopeptide and C-telopeptide demonstrated a wide scatter, but the values remained in the normal range. T levels were found to be below normal range for adult men in 12 of 32 (38%) subjects and the PTH levels above the normal range in 8 of 35 (23%) subjects. Bone resorption markers correlated inversely with BMD of the whole body, femur, and spine (r=-.22 to -.48). There was an inverse correlation between total T and spine BMD which became insignificant after correcting for body mass index (BMI). In addition, there was no correlation between free or bioavailable testosterone and BMD. 1,25-(OH)2D levels correlated inversely with BMD at the femur and whole body, but no association was found with PTH or 25 OH-D. CONCLUSIONS: Men over 75 years of age had a wide range of BMD but frequently had low values at femoral sites. T levels were below the normal range in 38% of men, and PTH levels were elevated in 23% of men. There was an inverse correlation between total T and spine BMD which may have been dependent on the common effect of BMI. Bone mineral density was inversely related to markers of bone resorption.     

Apoptosis and activation of the sphingomyelin-ceramide pathway induced by oxidized low density lipoproteins are not causally related in ECV-304 endothelial cells

Oxidized low density lipoproteins (oxLDL) are thought to play a central role in the development of atherosclerosis. Toxic concentrations of mildly oxidized LDL elicit massive apoptosis of endothelial cells (Escargueil-Blanc, I., Meilhac, O., Pieraggi, M. T. , Arnal J. F., Salvayre, R., Nègre-Salvayre, A. (1997) Arterioscler. Thromb. Vasc. Biol. 17, 331-339). Since the lipid mediator ceramide emerged as a potent inducer of apoptosis, we aimed at investigating the occurrence of ceramide formation and its potential role in oxLDL-induced apoptosis. In ECV-304 endothelial cells, toxic concentrations of oxLDL triggered an early activation of the sphingomyelin-ceramide pathway, as shown by both sphingomyelin hydrolysis and ceramide formation. N-Tosyl-L-phenylalanyl chloromethyl ketone (TPCK) and dichloroisocoumarin (DCIC), two serine-protease inhibitors (serpins), blocked the oxLDL-induced ceramide generation but, unexpectedly, did not inhibit the oxLDL-induced apoptosis. Conversely, treatment of endothelial cells by bacterial sphingomyelinase, under conditions effectively generating ceramide, did not induce apoptosis. In contrast, short-chain permeant C2- and C6-ceramides elicited apoptosis of ECV-304. However, the mechanisms of apoptosis triggered by C2-ceramide and by oxLDL were (at least in part) different, because C2-ceramide-induced apoptosis was calcium-independent, whereas oxLDL-induced apoptosis was calcium-dependent. In conclusion, it is suggested that oxLDL-induced apoptosis is calcium-dependent but independent of the activation of the sphingomyelin-ceramide pathway and that the toxic effect of short chain permeant ceramides is calcium-independent and does not mimic the effect of natural ceramides induced by oxLDL.     

Regulation of the assembly and secretion of very low density lipoproteins by the liver

Recent studies have suggested that there are three sites at which VLDL secretion by the liver may be controlled: (i) Newly synthesised apo-B either remains associated with the RER membrane and is degraded by the ubiquitin/proteasome system, or is translocated into the lumen and incorporated into lipid poor VLDL precursors; (ii) the lumenal apo-B is either degraded or moves on, and (iii) acquires the remaining VLDL lipids in the SER/cis-Golgi. Newly synthesised apo-B, at the cytosolic side of the RER, is stabilised and protected from degradation by the chaperone protein, hsp-70. Triacylglycerol, cholesterol ester and phospholipids have all been implicated in the translocation of apo-B and microsomal triglyceride protein plays a major role. If translocation does not occur then the apo-B is degraded. Dietary fish-oils, but not sunflower oil, inhibit movement of apo-B containing precursors from the RER and their assembly with lipids and target lumenal apo-B to degradation. This effect is reversed by inhibition of lumenal proteolysis, but not by inhibition of cytosolic proteolysis. Therefore lumenal degradation of apo-B and secretion appear to be in balance, so that if assembly of VLDL precursors is slowed, then degradation becomes predominant. If however, degradation is inhibited then VLDL assembly can proceed. These observations suggest that movement of VLDL precursors from the RER lumen to the second stage of assembly may be a further regulated step.     

Diurnal heterogeneity in structure and function of low density lipoproteins of normolipidemic males

Structural changes in low density lipoproteins (LDL) have been shown to alter their metabolism and atherogenic potential. We investigated the diurnal changes in size and composition of LDL in seven healthy, non-obese, normolipidemic male volunteers consuming a standard diet (14.5% protein, 31.9% fat, 53.6% carbohydrate and 383 mg cholesterol/day) and continuing their daily routine. The food was divided into three meals and three snacks, and blood samples were obtained at 7 AM (after 12 h fasting), noon, 8 PM, midnight and 3 AM. LDL were isolated by both sequential and density gradient ultracentrifugation (d = 1.019 - 1.050 g/ml), and analyzed for lipids, apolipoproteins, size, and affinity to LDL receptors. Diurnal LDL preparations differ from fasting LDL in both chemical and physical parameters. The former get richer in triglyceride (TG/cholesterol weight ratio 0.23 vs. 0.16), larger in diameter (21.2 +/- 0.2 vs. 22.4 +/- 0.1 nm), and enriched in a more buoyant fraction (74.0 +/- 4.6 vs. 41.9 +/- 3.8% of LDL cholesterol in d = 1.019 - 1.035 g/ml). These structural changes in LDL were associated with enhanced affinity to LDL receptors in both human skin fibroblasts and HepG2 cells, as demonstrated by competition experiments with fasting human 125I-LDL. The observed diurnal heterogeneity in both the structure and the function of LDL may be attributed to the absorptive state as it did not occur during prolonged fasting. These diurnal changes may be important for better understanding LDL metabolism in vivo and for the elucidation of the atherogenic process.