ADRA2A is involved in neuro-endocrine regulation of bone resorption.

Adrenergic stimulation is important for osteoclast differentiation and bone resorption. Previous research shows that this happens through ß2-adrenergic receptor (AR), but there are conflicting evidence on presence and role of α2A-AR in bone. The aim of this study was to investigate the presence of α2A-AR and its involvement in neuro-endocrine signalling of bone remodelling in humans. Real-time polymerase chain reaction (PCR) and immunohistochemistry were used to investigate α2A-AR receptor presence and localization in bone cells. Functionality of rs553668 and rs1800544 single nucleotide polymorphism SNPs located in α2A-AR gene was analysed by qPCR expression on bone samples and luciferase reporter assay in human osteosarcoma HOS cells. Using real-time PCR, genetic association study between rs553668 A>G and rs1800544 C>G SNPs and major bone markers was performed on 661 Slovenian patients with osteoporosis. α2A-AR is expressed in osteoblasts and lining cells but not in osteocytes. SNP rs553668 has a significant influence on α2A-AR mRNA level in human bone samples through the stability of mRNA. α2A-AR gene locus associates with important bone remodelling markers (BMD, CTX, Cathepsin K and pOC). The results of this study are providing comprehensive new evidence that α2A-AR is involved in neuro-endocrine signalling of bone turnover and development of osteoporosis. As shown by our results the neurological signalling is mediated through osteoblasts and result in bone resorption. Genetic study showed association of SNPs in α2A-AR gene locus with bone remodelling markers, identifying the individuals with higher risk of development of osteoporosis.

Interleukin-1α gene variants influence bone mineral density and the risk of osteoporotic hip fractures in elderly Slovenian people.

BACKGROUND: Osteoporosis is a skeletal disorder, characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to increased risk of fracture. Recently, the role of age-related pro-inflammatory cytokines, such as interleukin (IL)-1α, in stimulating bone resorption has been suggested. As osteoporosis has a strong genetic background, the aim of our study was to evaluate the association of two IL-1α gene single nucleotide polymorphisms (SNPs) rs2071375 (+12534G>A) and rs17651 (+4845G>T) with osteoporotic phenotypes as well as to find the association with IL-1α gene expression in human bone tissue. METHODS: Genotyping was performed in 671 Slovenian participants, 125 elderly men, 490 post- and 56 premenopausal women. Bone mineral density (BMD) at the lumbar spine, femoral neck and total hip were measured. Biochemical markers of bone turnover were measured in women. RESULTS: Significant association of GG/TA haplotype with higher femoral neck and total hip BMD in elderly men and women was shown (p=0.009 and 0.030, respectively). In men, the association of the GG/GG haplotype with higher femoral neck BMD was of limited statistical significance (p=0.050). In women, significant association of studied genetic variants with serum C-terminal crosslinking telopeptides of type I collagen and bone alkaline phosphatase were found (p=0.033 and 0.029, respectively). No influence on IL-1α expression was found. Finally, significantly lower odds ratio for hip fracture associated with the presence of TA haplotype was found (p=0.026). CONCLUSIONS: Our results of the association of IL-1α gene single nucleotide polymorphisms (SNPs) rs2071375 (+12534G>A) and rs17651 (+4845G>T) with osteoporotic features indicate its role in pathogenesis of osteoporosis. However, these findings need further functional and clinical confirmation.

BMD values and GSTM3 gene polymorphisms in combination with GSTT1/GSTM1 genes: a genetic association study in Slovenian elderly.

BACKGROUND: Much research suggests that oxidative stress is associated with osteoporosis development. Glutathione S-transferases mu3 (GSTM3) are an important group of detoxifying enzymes that eliminate oxidative stress-related products. OBJECTIVES: To examine the associations of functional GSTM3 gene polymorphisms (Val224Ile and insdelAGG), their haplotypes and, in combination with GSTT1-null and GSTM1-null polymorphisms, with bone mineral density (BMD) measured at femoral neck (_fn), lumbar spine (_ls) and total hip (_th) and biochemical bone turnover markers in 593 Slovenian elderly women and 119 Slovenian elderly men. METHODS: GSTM3, GSTT1-null and GSTM1-null gene polymorphisms using sizing denaturing high-performance liquid chromatography, triplex PCR method or real-time PCR; BMD_fn, BMD_ls, BMD_th values using dual energy X-ray absorptiometry, and plasma osteocalcin, serum bone alkaline phosphatase and free soluble tumor necrosis factor (ligand) superfamily, member 11 (sRANKL) concentrations using a solid-phase, two-site chemiluminescent enzyme-labeled immunometric assay, radioimmunoassay or enzyme immunoassay were determined. Statistical analysis was performed using one-way and two-way ANCOVA with adjustment for potential confounders (age, height and weight). RESULTS: The (borderline) significant differences in BMD_th and BMD_fn values between genotype subgroups of Val224Ile polymorphism of GSTM3 gene (p = 0.057 and 0.053, respectively) with the lowest BMD values among heterozygotes and between 224Ile-insAGG haplotype subgroups (p = 0.048 and 0.019, respectively) were found. Significant differences of BMD_fn between the 224Ile-delAGG haplotype subgroups were observed (p = 0.012). Association of 224Val-insAGG with BMD_fn was of borderline significance (p = 0.062). CONCLUSION: The results of our study demonstrate the genetic association between detoxifying enzyme GSTM3 and BMD variation, suggesting that the Val224Ile polymorphism and 224Ile-insAGG haplotype could be used for further evaluation of the impact of GSTs gene polymorphisms on osteoporosis, using larger cohorts in searching for osteoporosis risk markers.

-1227C>T polymorphism in the pleiotrophin gene promoter influences bone mineral density in postmenopausal women.

Our gene expression microarray data of primary cultures of osteoblasts revealed that the expression of the pleiotrophin (PTN) gene is decreased in osteoporosis. PTN is involved in osteoblasts' proliferation and differentiation, response to mechanical stimuli and cross-talk with Wnt signaling. On the basis of these findings, we studied the PTN gene as a candidate gene for genetic susceptibility to osteoporosis. The aim of the study was to evaluate the association of two PTN gene promoter polymorphisms with osteoporotic phenotype in postmenopausal women. 530 postmenopausal women, 480 without and 50 with hip fracture, were genotyped for the presence of PTN gene promoter polymorphisms -1734C>T (rs161335) and -1227C>T (rs321198). Three common haplotypes, CC (14.2%), CT (42.8%) and TC (42.9%), were inferred. Bone mineral densities (BMDs) at lumbar spine and (contralateral) hip were measured. In non-osteoporotic postmenopausal women without hip fracture, the association of -1227C>T and CT haplotype with lumbar spine BMD was shown (p=0.014 and 0.014). No other significant association of the studied genotypes and haplotypes in the PTN gene promoter with BMDs was found. Comparing age-matched postmenopausal women with and without hip fractures, no differences in frequency distributions of the studied genotypes and haplotypes was shown. For the first time we have shown that, in postmenopausal women, the PTN gene promoter polymorphism -1227C>T and CT haplotype could contribute to the genetic background of osteoporosis, but these findings need further functional and clinical confirmation.

Association between adiponectin and low-grade albuminuria is BMI-dependent in type 2 diabetes.

AIM: Low-grade albuminuria is a marker of increased risk for both cardiovascular and renal disease. Adiponectin, with its insulin-sensitizing, anti-inflammatory and antiatherogenic properties, is associated with cardiovascular as well as renal disease. Limited and conflicting data exist on the association of adiponectin with low-grade albuminuria. Our aim was to explore the association of plasma adiponectin and low-grade albuminuria in patients with type 2 diabetes. Furthermore, we were interested whether this association is dependent upon insulin sensitivity. METHODS: In this cross-sectional study, plasma adiponectin and urinary albumin excretion rate (UAER) were determined in 71 patients by radioimmunoassay. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp and expressed as the M value. The relationship between variables was described using univariate and multiple linear regression. RESULTS: Adiponectin and UAER were negatively associated (R = -0.285, p < 0.05) only in patients with BMI >25. The association was independent of the clamp-derived M value, gender, BMI, arterial pressure or cholesterol. CONCLUSION: In obese patients with type 2 diabetes, there is an inverse association between adiponectin and low-grade albuminuria, the association being independent of insulin resistance. The consequences of such a relationship in terms of renal disease progression and cardiovascular survival remain to be evaluated.

Adipocytokines are associated with renal function in patients with normal range glomerular filtration rate and type 2 diabetes.

INTRODUCTION: Adipocytokines represent a molecular link between metabolic factors and vascular function. The purpose of our study was to investigate the relationship between adiponectin, leptin and renal function parameters in patients with glomerular filtration rate (GFR) above 90 ml/min/m(2) and type 2 diabetes. MATERIALS AND METHODS: In 52 patients, plasma (P-) and urinary (U-) adiponectin and leptin were determined by radioimmunoassay and ELISA, respectively. Kidney function was assessed with GFR (plasma iohexol clearance) and albuminuria (radioimmunoassay). RESULTS: The patients were aged 58+/-8 years and had a mean BMI value of 31.2+/-5.2 kg/m(2). Our measurements yielded the following values, expressed as median (25th percentile, 75th percentile): P-adiponectin 11.0 (7.1, 14.5) microg/ml, P-leptin 20.7 (9.6, 35.9)ng/ml, U-adiponectin 0.8 (0.3, 1.2) microg/mg creatinine, and U-leptin 1.0 (0.4, 1.9) microg/mg creatinine. Albuminuria correlated with P-adiponectin (R=-0.31, p=0.03), and GFR correlated with U-leptin (R=-0.32, p=0.04). CONCLUSIONS: Adiponectin and leptin are associated with parameters of renal function already at the stage of apparently normal kidney function in type 2 diabetes. The exact mechanisms of the adipocyte-vasculature axis still remain to be elucidated.

Analysis of association of LRP5, LRP6, SOST, DKK1, and CTNNB1 genes with bone mineral density in a Slovenian population.

The Wnt pathway has a bifunctional role in bone mass regulation, influencing osteoblasts and osteoclasts. The Wnt pathway genes are therefore candidate genes for susceptibility to osteoporosis. In our study, we focused on the effects of polymorphisms in selected Wnt pathway genes: low-density lipoprotein receptor-related proteins 5 and 6 (LRP5 and LRP6), Dickkopf1 (DKK1), sclerostin (SOST), and beta-catenin (CTNNB1). We genotyped 652 subjects for the following polymorphisms: A1330V in LRP5; I1062V in LRP6; E232K in DKK1; D32Y, G34V, and N287S in CTNNB1; and -1397_-1396insGGA in SOST. Bone mineral density (BMD) was also measured. The allele frequencies were as follows: for A1330V C:T = 87%:13%, for I1062V C:T = 20%:80%, and for -1397_-1396insGGA-:GGA = 64%:36%. The studied nucleotide changes in the DKK1 and CTNNB1 genes were shown not to be polymorphic. In a Slovenian population, no association was shown between lumbar spine and femoral neck BMD in A1330V (P = 0.151 and 0.243) and in I1062V (P = 0.209 and 0.405). We observed a difference between SOST genotypes, corresponding to an allele dose effect, which was borderline significant for lumbar spine and femoral neck BMD (P = 0.047 and 0.085); but this did not survive the adjustment for multiple testing. These results indicate that a larger sample size would be necessary to detect these subtle effects. Our results suggest that A1330V in LRP5, I1062V in LRP6, and -1397_-1396insGGA in SOST are not associated with BMD in the Slovenian population.

Cathepsin K predicts femoral neck bone mineral density change in nonosteoporotic peri- and early postmenopausal women.

OBJECTIVE: Cathepsin K is a cysteine protease that plays an essential role in organic bone matrix degradation. The aim of our study was to seek correlation of serum cathepsin K levels and a change in bone mineral density (BMD) over a 3-year period in a population of healthy nonosteoporotic women. The secondary end points were the correlations of serum cathepsin K with cross-sectional BMD and with other serum bone turnover markers and age. DESIGN: In 43 healthy women aged 42 to 57 years, blood samples for determination of cathepsin K, osteocalcin, bone alkaline phosphatase, C-terminal cross-linking telopeptide of type I collagen, osteoprotegerin, and nuclear factor kappaB ligand were collected at the time of the first BMD measurement. BMD measurements were repeated after 3 years. RESULTS: We found a moderate negative correlation of serum cathepsin K levels with change in femoral neck BMD, but none with change in spinal BMD. There were no significant correlations between cross-sectional BMD of the spine or femoral neck and serum levels of cathepsin K. Serum levels of cathepsin K were not significantly correlated with any bone turnover markers studied or with age. CONCLUSIONS: Serum cathepsin K does not seem to represent a surrogate for bone turnover markers used at present, but it might be useful as a predictor of cortical bone loss.

Assessment of insulin resistance in young women with polycystic ovary syndrome.

OBJECTIVES: To determine whether serum levels of potential markers could detect insulin resistance (IR) in young women with polycystic ovary syndrome (PCOS). METHODS: Serum levels of fasting glucose, insulin, intact proinsulin, resistin, and adiponectin were measured in 50 women with PCOS and known homeostatic model assessment (HOMA)-IR values (>or=2 indicating IR). The women were all younger than 25 years. RESULTS: Of the 50 women, 49 had undetectable levels of resistin, 50 had intact proinsulin levels within the normal range, and 50 had adiponectin levels of 8.4+/-3.3 mg/L, just below the normal range. When groups were compared, however, the 26 women (52%) with IR (HOMA-IR values >or=2) had significantly higher intact proinsulin levels (3.2+/-2.0 pmol/L vs 1.8+/-1.0 pmol/L; P<0.005) and significantly lower adiponectin levels (7.2+/-2.9 mg/L vs 9.7+/-3.3 mg/L; P<0.01), than the 24 women (48%) without IR. CONCLUSION: Serum levels of intact proinsulin, resistin, or adiponectin were not detectors of IR in individual young women with PCOS.

Exonic, but not intronic polymorphisms of ESR1 gene might influence the hypolipemic effect of raloxifene.

UNLABELLED: Studies have shown that selective modulator of estrogen receptor raloxifene, exerts hypolipemic properties at least partially through estrogen receptor alpha activation. To test the hypothesis that polymorphisms of estrogen receptor alpha are associated with the influence of 6 months raloxifene treatment on serum lipids, two intronic (PvuII and XbaI), and one exonic polymorphism (P325P) were analyzed in 49 postmenopausal women, mean age 62.5+/-5.7 years. In all subjects, the total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides were determined before and after 6 months of raloxifene treatment. We were unable to find any relationship between estrogen receptor alpha genotype and serum lipids at baseline. At the end of 6 months treatment with raloxifene, the mean decrease of total cholesterol and LDL cholesterol, independently of genotypes, was highly significant, but no influence on HDL and triglycerides concentrations was found. Neither the PvuII nor XbaI ESR1 gene polymorphisms were associated with the magnitude of lipid changes after 6 months treatment, whereas the subjects with non-CC genotype of P325P mutation had significantly lower total cholesterol and LDL cholesterol concentrations, and higher decline of total cholesterol (p<0.05). CONCLUSION: Our data suggest that exonic, but not intronic polymorphisms of estrogen receptor alpha gene might intensify the cholesterol lowering effect of raloxifene.

Decreased androgen levels and improved menstrual pattern after angiotensin II receptor antagonist telmisartan treatment in four hypertensive patients with polycystic ovary syndrome: case series.

We describe 4 consecutive hypertensive women with polycystic ovary syndrome, classified according to the National Institute of Child Health and Human Development (NICHD) criteria, treated with telmisartan 40 mg/d for six months. Blood pressure, menstrual pattern, body mass index (BMI), homeostasis model assessment of insulin resistance, testosterone, dehydroepiandrosterone sulfate (DHEAS), and androstenedione were recorded and measured before and after telmisartan treatment. Obese hypertensive polycystic ovary syndrome patients had a decrease in systolic blood pressure. Marked drop-off in serum androgen concentrations was observed in all four patients. Three patients improved their menstrual cyclicity. The improvements were independent of changes in weight. The reduction of androgen concentrations and improvement in menstrual pattern was achieved despite a non-significant change of fasting insulin levels in patients, who were not considered severely insulin resistant at baseline. These findings may provide a new basis for a proper choice of the antihypertensive drug in hypertensive women with polycystic ovary syndrome.

Association of TNFSF11 gene promoter polymorphisms with bone mineral density in postmenopausal women.

OBJECTIVES: The receptor activator of nuclear factor-kappaB ligand (RANKL) is recognized as one of the important regulators of osteoclastogenesis. The expression of the tumour necrosis factor superfamily, member 11 (TNFSF11) gene, which encodes for RANKL protein, is increased relative to the expression of osteoprotegrin in cases of senile osteoporosis with hip bone fracture. Our aim was to find polymorphisms in the TNFSF11 gene promoter and to investigate their possible association with bone mineral density (BMD). METHODS: The TNFSF11 gene promoter region was screened for the presence of new sequence variations by direct sequencing. DNA sequencing revealed the presence of four sequence variations: -290C>T, -643C>T, -693G>C and -1594G>A. Association of the discovered polymorphisms with BMD was investigated in 115 Slovenian postmenopausal women, using restriction fragment length polymorphism analysis. After a year, bone loss in the association with the identified sequence variations was evaluated in 43 postmenopausal women. RESULTS: Three of the discovered sequence variations (-290C>T, -643C>T, -693G>C) proved to be polymorphic, whereas variation -1594G>A was only found in one patient. The frequencies of genotypes were as follows: CC (27.8%), CT (43.5%), TT (28.7%) for -290C>T polymorphism; CC (23.5%), CT (47.8%), TT (28.7%) for -643C>T polymorphism; and GG (22.6%), GC (51.3%), CC (26.1%) for -693G>C polymorphism. A statistically significant association of genotype with BMD at the femoral neck was observed only in the -290C>T polymorphism. Genotype CC was associated with lower BMD than the TT genotype (P = 0.022). In polymorphism -693G>C, a significant difference in bone loss rate was observed in total hip (P = 0.011) and femoral neck BMD (P = 0.037). CONCLUSIONS: Four sequence variations were identified in the studied region of TNFSF11 gene promoter. Our results of preliminary clinical evaluation suggest that the -290C>T polymorphism in the TNFSF11 gene promoter could contribute to the genetic regulation of BMD.

MiR-148a the epigenetic regulator of bone homeostasis is increased in plasma of osteoporotic postmenopausal women.

BACKGROUND: Osteoporosis is a prevalent skeletal disorder characterized by reduced bone mineral density and microarchitectural deterioration of bone tissue, resulting in bone fragility and low-trauma fractures. Imaging techniques are routinely used to detect low bone mass; however, they are unable to identify deterioration of bone quality. Recently, microRNAs have emerged as regulators of bone remodelling and potentially also as a new class of sensitive biomarkers of bone health to aid in diagnosis and treatment monitoring of osteoporosis. METHODS: To identify new plasma-based biomarkers associated with osteoporosis we analyzed microRNAs isolated from plasma samples of 74 postmenopausal women divided into osteoporotic (N = 17) and control groups (N = 57). A prior microRNA screening was performed where a few showed promise for further analysis. Quantitative polymerase chain reaction was used to investigate differences in expression of let-7d-5p, let-7e-5p, miR-30d-5p, miR-30e-5p, miR-126-3p, miR-148a-3p, miR-199a-3p, miR-423-5p and miR-574-5p between the two groups. Furthermore, correlation analysis between microRNA expression levels and patient bone mineral density measurements and fracture risk assessment tool (FRAX) as well as trabecular bone scores were performed. RESULTS: Expression of miR-148a-3p was significantly higher (p = 0.042) in the osteoporotic patient group compared to the controls. In addition, we identified correlations between miR-126-3p (ρ = 0.253, p = 0.032) and 423-5p (ρ = -0.230, p = 0.049) and parameters of bone quality and quantity. CONCLUSION: The results from our study, together with the functional role of miR-148a-3p in bone suggest that this microRNA could be considered as a potential new plasma-based biomarker for pathological changes associated with osteoporosis.

Association of the osteoprotegerin gene polymorphisms with bone mineral density in postmenopausal women.

OBJECTIVES: Osteoprotegerin (OPG) is a recently discovered member of the tumour necrosis factor receptor superfamily. It plays a crucial role in the control of bone resorption and its gene could therefore be a good candidate gene for osteoporosis. The aim of our work was to find polymorphisms in the OPG gene and to investigate their possible contribution to the genetic susceptibility to osteoporosis by testing for their association with bone mineral density (BMD). METHODS: The whole OPG gene coding region was screened for the presence of polymorphisms in a group of 60 osteoporotic women by single-strand conformation polymorphism analysis (SSCP) approach. Association of the discovered polymorphisms with bone mineral density was investigated in 136 Slovenian postmenopausal women. RESULTS: We detected eight OPG gene polymorphisms that were confirmed by direct DNA sequencing, deletion 4752_4753delCT and nucleotide substitutions 1181G>C, 1217C>T, 1284G>A, 4501C>T, 6893A>G, 6950A>C and 8738T>A. Nucleotide substitutions 1284G>A and 8738T>A have not been previously described. Polymorphisms 4752_4753delCT, 6893A>G and 6950A>C were in complete linkage and the same was true for 1217C>T and 4501C>T. The association with BMD was found only for polymorphism 1181G>C. Subjects with genotype 1181GG had significantly lower lumbar spine BMD than subjects displaying 1181GC. CONCLUSIONS: By our approach we detected eight polymorphisms in the OPG gene. According to our analysis polymorphism 1181G>C is associated with BMD and could therefore be considered as an element of genetic susceptibility to osteoporosis.

No major effect of estrogen receptor beta gene RsaI polymorphism on bone mineral density and response to alendronate therapy in postmenopausal osteoporosis.

Genetic factors play an important role in the pathogenesis of osteoporosis. The genes involved are, however, still largely unknown. In the present study, we have investigated whether sequence variations in the estrogen receptor beta (ERbeta) gene are associated with bone mineral density (BMD) and biochemical markers of bone turnover in 79 Slovenian postmenopausal women with osteoporosis. We also assessed the response by BMD and bone markers to antiresorptive therapy with bisphosphonate alendronate. All eight exons of ERbeta gene were amplified by polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis. Potentially mutated samples were found only in exon 5 and sequence analysis identified the presence of a silent mutation in codon 328 with a nucleotide substitution GTG to GTA. For easier detection of this silent mutation, the RsaI restriction fragment length polymorphism analysis was developed. The frequencies of genotypes were as follows: Rr 5.1% and RR 94.9%. Between both genotypes, no significant differences in baseline lumbar spine and femoral neck BMD or in bone markers osteocalcin and deoxypyridinoline were observed. Similarly, no significant difference between RR and Rr genotypes in BMD or bone markers after 1 year of therapy was found. The increase in lumbar spine BMD after therapy was the only parameter that approached statistical significance (P=0.099). Patients with genotype Rr showed a smaller increase compared to those with RR. Our results suggest that RsaI polymorphism of ERbeta gene is probably not an important genetic determinant of BMD and does not significantly influence the responsiveness to alendronate therapy.

Vitamin D receptor gene polymorphism and bone metabolism during low-dose oral contraceptive use in young women.

With the aim to determine whether bone metabolism in young women using low-dose oral contraception is influenced by vitamin D receptor (VDR) genotype, we designed the prospective clinical study of 41 healthy women aged 20-27 years. Twenty-one women of the study group were prescribed an oral contraceptive (30 microg ethynyl estradiol and 150 microg levonorgestrel) and 20 women of the control group a nonhormonal contraceptive or none. Biochemical markers of bone metabolism (bone-specific alkaline phosphatase, osteocalcin, deoxypyridinoline) and VDR genotype, using BsmI endonuclease, were determined. After 3 months in the study group, the BB genotype subgroup showed significantly decreased osteocalcin (p = 0.010), in the Bb genotype subgroup bone-specific alkaline phosphatase (p = 0.043) and osteocalcin (p = 0.006) decreased, and in the bb genotype subgroup no changes were observed. In the control group, there were no significant changes in markers of bone metabolism regarding VDR genotype. In conclusion, our study shows that in young women VDR gene polymorphism could influence bone metabolism during low-dose oral contraceptive use.

Basal glucose level as an independent predictor of fertilization rate in patients without polycystic ovary syndrome included in an in-vitro fertilization program.

Insulin resistance is a common characteristic of women with polycystic ovary syndrome (PCOS) who are known to differ in their in-vitro fertilization outcomes compared to non-PCOS patients. As insulin resistance can be found in a considerable proportion of normal individuals, we assessed its contribution to ovarian responsiveness and fertilization rate. 26 non-PCOS patients undergoing IVF for the first time were investigated. Insulin resistance was evaluated by using a euglycemic hyperinsulinemic clamp technique. According to multiple regression analysis insulin sensitivity, expressed as insulin stimulated glucose disposal rate, during euglycemic clamp (r = -0.81, p < 0.05 and r = -0.89; p < 0.01) and basal estradiol level (r = -0.54; p < 0.05 and r = -0.56; p < 0.05) appeared significant negative predictors of the number of fertilized oocytes and embryos, respectively. Furthermore, basal glucose level appeared independently as a significant positive predictor of the number of fertilized oocytes and the number of embryos. (r = 0.90; p < 0.01 and r = 0.96; p < 0.01 respectively). We conclude that blood glucose concentration and insulin resistance respectively are independent predictors of IVF outcome.

Raloxifene pharmacodynamics is influenced by genetic variants in the RANKL/RANK/OPG system and in the Wnt signaling pathway.

BACKGROUND: Raloxifene is a selective estrogen receptor (ER) modulator (SERM) used for the treatment of osteoporosis. However, its efficacy and also its safety vary greatly among treated patients, and it might be influenced by the individuals' genetic background. As the receptor activator of the nuclear factor κB (RANK) ligand (RANKL)/RANK/osteoprotegerin (OPG) system is essential for osteoclastogensis and Wnt signaling pathway for osteoblastogenesis, we decided to evaluate the raloxifene treatment in regard to selected polymorphisms in key genes of these two main bone regulatory pathways. METHODS: Fifty-six osteoporotic postmenopausal women treated with raloxifene were genotyped for 11 polymorphisms located in six genes: -290C>T, -643C>T, and -693G>C in tumor necrosis factor receptor superfamily member 11 (TNFSF11), +34694C>T, +34901G>A, and +35966insdelC in tumor necrosis factor receptor superfamily member 11A (TNFRSF11A), K3N and 245T>G in tumor necrosis factor receptor superfamily member 11B (TNFRSF11B), A1330V in LRP5, I1062V in LRP6, and -1397_-1396insGGA in SOST. For evaluation of treatment efficacy, bone mineral density (BMD) and biochemical markers of bone turnover were measured. RESULTS: One-year change in total hip BMD was associated with +34901G>A in TNFRSF11A (p=0.040), whereas, for lumbar spine BMD, the association was shown for -1397_-1396insGGA in SOST (p=0.015). C-terminal crosslinking telopeptides of type I collagen (CTX) concentrations showed significant association with -643C>T single nucleotide polymorphism (SNP) in TNFSF11 (p=0.049) and +34694C>T in TNFRSF11A (p=0.022). No other association was found between 1-year change in BMDs or biochemical markers and the studied SNPs. CONCLUSIONS: We have shown that, in postmenopausal osteoporotic women treated with raloxifene, the efficacy of raloxifene treatment might be influenced by +34901G>A in TNFRSF11A gene and -1397_-1396insGGA in the SOST gene as well as -643C>T in TNFSF11 gene and +34694C>T in TNFRSF11A gene. However, these findings need additional functional and clinical confirmation for potential pharmacogenetic use in the future.

Testing GSTP1 genotypes and haplotypes interactions in Slovenian post-/pre-menopausal women: novel involvement of glutathione S-transferases in bone remodeling process.

OBJECTIVES: Osteoporosis (OP) is an age-related disease associated with increased production of reactive oxygen species (ROS) and a reduction in antioxidant defense system, such as low activity of glutathione S-transferase (GST) family. The enzyme activity of the member of GSTs, GSTP1, depends on gene polymorphisms such as: Ala114Val and Ile105Val. The aim of this study was to evaluate the association between genetic polymorphisms of the GSTP1 gene and BMD variation and biochemical bone remodeling markers in 523 Slovenian pre- and post-menopausal women. STUDY DESIGN: Observational pilot study in a representative cohort of Slovenian patients with adjustment for potential confounders (age, height, weight, years since menopause, smoking status and glucocorticoid use) using univariate one-way and two-way analyses. MAIN OUTCOME MEASURES: Ala114Val and Ile105Val polymorphisms genotypes of GSTP1 gene, bone mineral density (BMD) values of total hip (_th), femoral neck (_fn) and lumbar spine (_ls), plasma osteocalcin (OC), serum bone alkaline phosphatase (BALP), free soluble RANKL and serum osteoprotegerin (sOPG) concentrations were determined. RESULTS: Our results show that the Ala114Val heterozygotes are (borderline) significantly associated with higher concentrations of pOC (p=0.052) and decreased BMD_fn values (p=0.053) and the same trend is shown for BMD_th and BMD_ls values in osteopenic postmenopausal women. Furthermore, significantly higher concentrations of pOC were determined among Val allele carriers of Ile105Val gene polymorphism (p=0.037) and in carriers with the absent 114Ala-105Ile haplotype combination, again in osteopenic post-menopausal women. In addition, in pre-menopausal women the significant associations between sOPG and Ala114Val genotypes subgroups and between sBALP and Ile105Val genotypes subgroups, alone or in combination with Ala114Val, were determined (0.032, 0.026 and 0.008, respectively). CONCLUSIONS: Since significant associations existed in Ala114Val genotype and 114Ala-105Ile haplotype subgroups, these variations can be useful for determining low BMD and high pOC risk in postmenopausal women.

Antioxidant enzymes GSR, SOD1, SOD2, and CAT gene variants and bone mineral density values in postmenopausal women: a genetic association analysis.

OBJECTIVE: Oxidative stress participates in decreasing bone formation and stimulating bone resorption. Furthermore, antioxidant enzymes have been observed to have low protective activity in women with osteoporosis.The aim of the present study was to examine any association of selected gene polymorphisms of the glutathione S-reductase (GSR), superoxide dismutase (SOD1 and SOD2), and catalase (CAT) genes, alone or in combination, with the bone mineral density (BMD) values of femoral neck (fn), lumbar spine (ls), and total hip (th) in Slovenian postmenopausal women. METHODS: The gene polymorphisms of CAT, GSR, SOD1, and SOD2 genes in 468 postmenopausal women were analyzed using restriction fragment length polymorphism and a fluorescent 5'-exonuclease genotyping method. BMD_fn, BMD_ls, and BMD_th were measured using dual-energy x-ray absorptiometry. Moreover, univariate statistic analysis and two-way analysis of variance for interaction testing were performed. RESULTS: A significant association of BMD_th values (P = 0.027) was found in genotype subgroups of 423-287G>A GSR polymorphism located in the third intron among postmenopausal women. Furthermore, women with at least one G allele showed significantly higher levels of BMD_fn (P = 0.044), BMD_th (P = 0.009), and BMD_ls (P = 0.043) than those that are AA homozygotes. Interestingly, the 423-287G>A_GSR*1154-393T>A_GSR combination was significantly associated with BMD_fn (P = 0.013) and BMD_th (P = 0.002) in postmenopausal women. CONCLUSIONS: The results of our study demonstrate for the first time that antioxidant enzyme GSR gene polymorphisms are significantly associated with BMD, suggesting that the A allele of 423-287G>A GSR polymorphism could contribute to decreased BMD values in postmenopausal women.