VDR gene ApaI polymorphism and risk of postmenopausal osteoporosis: a meta-analysis from 22 studies

OBJECTIVE

The ApaI polymorphism (G > T, rs7975232) of the vitamin D receptor (VDR) gene in the risk of postmenopausal osteoporosis has been widely researched, and the results have yielded conflicts. Therefore, we performed an updated pooled analysis to comprehensively assess the association between VDR ApaI polymorphism and postmenopausal osteoporosis risk.

METHODS

We searched eligible studies about ApaI polymorphism and osteoporosis through the PubMed, Embase, CNKI and Wanfang databases; case-control studies containing available genotype frequencies of A/a were chosen. We used the odds ratio with 95% confidence interval to assess the strength of this association. Sensitivity analysis and publication bias assessment were performed. Trial sequential analysis (TSA) was performed to evaluate a sufficient sample.

RESULTS

Twenty-two studies assessed the relationship between ApaI polymorphism and the risk of osteoporosis in postmenopausal women. The comprehensive analyses showed no significant association for ApaI polymorphism with postmenopausal osteoporosis in the overall population, equally valid for Asian and Caucasian subgroups with any genetic model. TSA still indicated the results were robust.

CONCLUSION

The present meta-analysis suggests that the VDR ApaI genotype may not affect the risk of postmenopausal osteoporosis in Asians and Caucasians.

[Progress of researches on roles of dendritic cells in immune tolerance caused by Echinococcus infections]

Dendritic cells (DCs), a type of antigen-presenting cells (APC), are recognized as an important regulator of immune response and immune tolerance, and play a critical role in the host innate immunity and adaptive immunity. Previous studies have shown that the long-term parasization of Echinococcus in the host is strongly associated with the host immune tolerance induced by DCs. This review summarizes the research progress of the role of DCs in host immune tolerance caused Echinococcus infection, aiming to provide the theoretical basis and insights into the management and immunotherapy of Echinococcus infections.

3,4-Methylenedioxymethamphetamine causes retinal damage in C57BL/6J mice

3,4-Methylenedioxymethamphetamine (MDMA) is a powerfully addictive psychostimulant with pronounced effects on the central nervous system, but the precise mechanism of MDMA-induced toxicity remains unclear, specifically on the retina. This study was performed to investigate the effects of MDMA treatment on the retina and explore the underlying mechanism. C57BL/6J mice were randomly divided into control and MDMA groups. Mice were treated with MDMA at progressively increasing doses (1-6 mg/kg) intraperitoneally 4 times per day. Electroretinography was used to test the retinal function. Pathological changes of the retina were examined by toluidine blue staining and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay. Enzyme-linked immunosorbent assays were used to measure the levels of cytokines in the retina. Real-time polymerase chain reaction and Western blot were used to measure gene and protein expression in the retina, respectively. Our study showed that MDMA treatment impaired retinal function and decreased retinal thickness. MDMA treatment also increased transforming growth factor β as well as inflammatory factors in the retina. Moreover, MDMA treatment increased protein expression of matrix metalloproteinases (MMPs) and decreased tight junction protein expression in the retina. Our study indicated that treatment of MDMA caused retinal damage in C57BL/6J mice, associated with an increase of MMPs and a decrease of tight junction proteins.

A retrospective analysis of ovarian stimulation with letrozole in women undergoing artificial insemination by donor

The aim of this retrospective study was to determine the clinical pregnancy rate in women undergoing letrozole ovarian stimulation and artificial insemination by donor (AID). Between 2012 and 2015, 130 natural cycles, 939 letrozole cycles and 130 letrozole plus gonadotrophin cycles were conducted. Letrozole cycles were divided into three groups according to LH concentration on the day of HCG administration (LH <10 mIU/ml and follicle size ≥18 cm; LH ≤10 to <20 mIU/ml; and LH ≥20 mIU/ml). Pregnancy rates were 17.3%, 22.4% and 26.8%, respectively (P = 0.012). In women given 10 mIU/ml LH or more, logistic regression identified oestradiol (OR 1.002, 95% CI, 1.000 to 1.004, P = 0.029) and leading follicle size (OR 0.861, 95% CI, 0.772 to 0.960, P = 0.007) as significant predictive factors of pregnancy rate; the higher the oestradiol and the smaller the follicles, the better the pregnancy rate. The pregnancy rate was significantly higher in the letrozole plus gonadotrophin group than the letrozole group (P = 0.04). Better pregnancy rates can be achieved if LH surge occurs before HCG administration, especially with higher oestradiol and lower follicle size; treatment with letrozole plus gonadotrophin was significantly more effective than letrozole alone in AID.

Correlations of leukemia inhibitory factor and macrophage migration inhibitory factor with endometrial carcinoma

OBJECTIVE

To investigate the correlations of leukemia inhibitory factor (LIF) and macrophage migration inhibitory factor (MIF) with endometrial carcinoma.

MATERIALS AND METHODS

The study included 113 endometrial specimens from the Fourth Affiliated Hospital of Harbin Medical University, collected from May 2006 to October 2008, classified into normal endometrium, simple hyperplasia, complex hyperplasia, atypical hyperplasia, and endometrial carcinoma. The LIF and MIF expression of all 113 specimens was detected with immunohistochemistrical (IHC) method.

RESULTS

The MIF expression in hyperplastic endometrium and endometrial carcinoma increased significantly as compared with that in normal endometrium (p < 0.05 and p < 0.001, respectively), and its expression in endometrial carcinoma was also remarkably higher than that in hyperplastic endometrium (p < 0.001). The expressions of LIF in atypical hyperplasia and endometrial carcinoma were also significantly higher than that in the normal endometrium (p < 0.05), but it is not obviously higher in simple hyperplasia and complex hyperplasia than in the normal endometrium (p > 0.05). Furthermore, the expression of LIF showed no statistical difference between hyperplastic endometrium and endometrial carcinoma.

CONCLUSION

It could be speculated that MIF may be correlated with the occurrence of endometrial carcinoma. However, whether LIF also has a correlation with the occurrence of endometrial carcinoma still cannot be presumed.

Estrogens and epididymal function

Estrogen is synthesized in the male reproductive system and is found in high concentrations in rete testis and seminal fluids. This luminal estrogen targets estrogen receptors (ER) along the male reproductive tract, and in particular the efferent ductules, where ERalpha is abundant. However, both ERalpha and ERbeta are found in various regions of the male reproductive tract. The transgenic ER knockout mice (alphaERKO and betaERKO) have been used to help define the role of ER in the male. In the alphaERKO animal model, the efferent ductules are dramatically altered, forming an epithelium in which fluid reabsorption is inhibited and epithelial cells have greatly reduced numbers of lysosomes and organelles associated with endocytosis. The betaERKO male reproductive tract appears normal. Because these animals are transgenic and lack ER throughout development, we developed animal models using pure antiestrogen ICI 182,780 treatments in adult males. The data show that ERalpha participates in the regulation of the apical cytoplasm of non-ciliated cells of the efferent ductules, narrow cells of initial segment epididymis and clear cells in the remaining segments of the epididymis. There appears to be no effect on vas deferens. The inhibition of ERalpha function in the male leads to decreases in sperm concentrations and eventually to infertility. The current literature leaves the mechanisms of estrogen action in the male reproductive tract unsettled and raises the question of androgen's contribution to the regulation of fluid transport, especially in the efferent ductules.

Estrogen action and male fertility: roles of the sodium/hydrogen exchanger-3 and fluid reabsorption in reproductive tract function

Estrogen receptor alpha (ER alpha) is essential for male fertility. Its activity is responsible for maintaining epithelial cytoarchitecture in efferent ductules and the reabsorption of fluid for concentrating sperm in the head of the epididymis. These discoveries and others have helped to establish estrogen's bisexual role in reproductive importance. Reported here is the molecular mechanism to explain estrogen's role in fluid reabsorption in the male reproductive tract. It is shown that estrogen regulates expression of the Na(+)/H(+) exchanger-3 (NHE3) and the rate of (22)Na(+) transport, sensitive to an NHE3 inhibitor. Immunohistochemical staining for NHE3, carbonic anhydrase II (CAII), and aquaporin-I (AQP1) was decreased in ER alpha knockout (alpha ERKO) efferent ductules. Targeted gene-deficient mice were compared with alpha ERKO, and the NHE3 knockout and CAII-deficient mice showed alpha ERKO-like fluid accumulation, but only the NHE3 knockout and alpha ERKO mice were infertile. Northern blot analysis showed decreases in mRNA for NHE3 in alpha ERKO and antiestrogen-treated mice. The changes in AQP1 and CAII in alpha ERKO seemed to be secondary because of the disruption of apical cytoarchitecture. Ductal epithelial ultrastructure was abnormal only in alpha ERKO mice. Thus, in the male, estrogen regulates one of the most important epithelial ion transporters and maintains epithelial morphological differentiation in efferent ductules of the male, independent of its regulation of Na(+) transport. Finally, these data raise the possibility of targeting ER alpha in developing a contraceptive for the male.

Human estrogen receptor beta-specific monoclonal antibodies: characterization and use in studies of estrogen receptor beta protein expression in reproductive tissues

Investigation of the role of the second, more recently described estrogen receptor, denoted ERbeta, will be critical in understanding the molecular mechanisms underlying tissue-specific gene regulation by estrogens. Expression of ERbeta in a variety of tissues has been examined predominantly at the mRNA level, and there is little information regarding the cellular localization and size of the endogenous ERbeta protein, due, in part, to the limited availability of human ERbeta-specific antibodies. Thus, our aim was to generate specific antibodies to human ERbeta and use them to determine the tissue-specific distribution and size(s) of the ERbeta protein. To this end, we have cloned three different hybridoma cell lines that produce monoclonal antibodies specific for the hormone-binding domain of human ERbeta. The antibodies, made in mice against human ERbeta amino acids 256-505 (hormone binding domain lacking the F domain), are designated CFK-E12 (E12), CMK-A9 (A9) and CWK-F12 (F12) and were determined to be the IgG gamma1 isotype for E12, and IgG gamma2b for A9 and F12. All three monoclonal antibodies could be used to detect in vitro translated, baculovirus expressed, and cell transfected and expressed ERbeta protein by Western blot analyses, and all failed to detect ERalpha. A9 and F12 were able to immunoprecipitate efficiently the native form of ERbeta protein in the presence and absence of estradiol. Epitope mapping studies indicate that the E12 and F12 antibodies recognize overlapping peptide sequences in the N-terminal region of the hormone-binding domain, a region that is highly conserved among species. Immunocytochemical studies with these antibodies reveal nuclear-specific localization of the ERbeta protein in granulosa cells of the rat ovary. Nuclear ERbeta is also specifically localized in epithelial and some stromal cells of mouse and rat epididymis. Western blot analysis with protein extracts from ovarian granulosa cells of human, rat, mouse, and pig showed a ca. 52 kDa and an additional ca. 62-64 kDa band in these species. These results indicate the presence of two predominant molecular size forms of the ERbeta protein in ovarian granulosa cells and demonstrate the utility of these antibodies for detection of ERbeta in the human and in several other mammalian species.

Morphological analysis of endocytosis in efferent ductules of estrogen receptor-alpha knockout male mouse

Lack of estrogen receptor (ER) results in fluid accumulation and dilation of the efferent ductules, suggesting that the role of estrogen and ER in the male reproductive tract is related to fluid reabsorption in the ductules. In the present study, endocytosis of the nonciliated cells of the efferent ductules was compared morphologically between wild type (WT) and estrogen receptor-alpha knockout (alpha ERKO) male mice. The epithelial cells lining the WT efferent ductules were tall columnar in shape, whereas those of the alpha ERKO were low columnar. Immunocytochemically, the nonciliated cells of both genotypes showed positive reactions of sulfated glycoprotein-2, but the reaction products were reduced in amount in the alpha ERKO. Electron microscopy revealed that the nonciliated cells of the WT had numerous organelles for endocytosis such as coated pits and vesicles, tubules, endosomes, multivesicular bodies and lysosomes in the apical cytoplasm. These organelles were less developed in the nonciliated cells of the alpha ERKO. Morphometric analysis indicated that there was a significant reduction in area of endocytotic apparatus in the nonciliated cells of the alpha ERKO compared with that of the WT. A tracer study using gold particles demonstrated that the nonciliated cells of both WT and alpha ERKO efferent ductules were capable of taking up luminal contents. These results suggest that reabsorption of the luminal contents via endocytosis takes place in the efferent ductules but is greatly reduced in amount in the absence of ER alpha.

Three steroidal alkaloids from Buxus microphylla

Three new steroidal alkaloids have been isolated from the leaves and stems of Buxus microphylla Sieb et Zucc. They are buxmicrophylline B, C and D. Their structures were elucidated by extensive analysis of the spectral data.