Increased Risk of Herpes Zoster in Diabetic Patients Comorbid with Coronary Artery Disease and Microvascular Disorders: A Population-Based Study in Taiwan

We investigated the association between the risk of herpes zoster (HZ) and diabetes-related macrovascular comorbidities and microvascular disorders in diabetic patients. This retrospective study included 25,345 patients with newly identified HZ and age- and gender-matched controls retrieved from the National Health Insurance Research Database in Taiwan during the period of 2005 to 2011. Multivariate logistic regression analyses were used to calculate the odds ratios (OR) and to assess the risk factors for HZ in diabetic patients with associated macrovascular or microvascular disorders. Risk factors for HZ were significantly increased in cases of diabetes mellitus (DM) compared with those in cases of non-DM controls (20.2% vs. 17.0%, OR = 1.24, p<0.001). Results of age- and gender-adjusted analyses demonstrated a significantly higher risk of HZ in DM patients with accompanying coronary artery disease (CAD) (adjusted OR = 1.21, p<0.001) and microvascular disorders (aOR = 1.32, p<0.001) than in DM patients with other comorbidities but no microvascular disorders. Patients who took thiazolidinedione, alpha-glucosidase inhibitors and insulin had a higher HZ risk than those taking metformin or sulphonylureas alone (aOR = 1.11, 1.14 and 1.18, p<0.001, respectively). Patients who took insulin alone or in combination with other antidiabetic agents had a significantly higher risk of HZ (aOR = 1.25, p<0.001) than those who received monotherapy. Diabetic patients comorbid with coronary artery disease and associated microvascular disorders had an increased risk of HZ occurrence.     

Kentsin: tetrapeptide from hamster embryos produces naloxone-sensitive effects without binding to opioid receptors

The opioid nature of kentsin (Thr-Pro-Arg-Lys) and its ability to alter pain perception and intestinal transit were examined. Kentsin (30,000 nM) did not inhibit electrically stimulated contractions of the guinea pig ileum (GPI) or mouse vas deferens (MVD), nor did it cause a rightward displacement of the inhibitory concentration-response curves of the mu-selective opioid agonist PL017 in the GPI or the delta-selective agonist DPDPE in the MVD. Kentsin (10,000 nM) did not displace [3H] naloxone from rat brain homogenates. These results indicate that kentsin lacks opioid agonist and mu and delta opioid antagonist properties and does not bind to opioid receptors. In vivo, kentsin produced dose-dependent analgesia in both the hotplate and abdominal stretch tests when administered intracerebroventricularly (ICV) and intrathecally but not intravenously. The central analgesic effect of kentsin was partially antagonized by the opioid antagonist naloxone. Kentsin inhibited intestinal transit in a dose-dependent manner after ICV administration only. The intestinal antitransit effect of kentsin was not blocked by pretreatment with naloxone. These results suggest that kentsin acts centrally to produce both opioid and non-opioid effects. Further, the opioid-mediated analgesic effects of kentsin involve mechanisms other than direct interaction with opioid receptors.     

In vitro fertilisation of mouse oocytes reconstructed by transfer of metaphase II chromosomes results in live births

The interaction between nucleus and cytoplasm can be explored through nuclear transfer. We describe here another tool to investigate this interaction: MII meiotic apparatus transfer (MAT) between mouse oocytes. In this study, the MII oocyte meiotic apparatus or spindle from C57BL/6 mice, a black strain, was transferred into an enucleated metaphase oocyte from Kunming mouse, a white strain. The results showed that the enucleation rate by treating oocytes with 3% sucrose was 100%, but the electrofusion efficiency was very low, with only 17.6% of reconstructed karyoplast-recipient cytoplasm pairs fused. When the fused oocytes were exposed to spermatozoa from C57BL/6 mice, 9 of 11 (82%) were fertilised. Eight reconstructed embryos at 1- to 4-cell stages were transferred into the oviducts of two synchronously pregnant Kunming strain fosters and one delivered two normal C57BL/6 offspring. This study indicates that MII meiotic apparatus or spindle sustains normal structure and function after micromanipulation and electrofusion. MAT provides a model for further research on the application of this technique to assisted human reproduction.     

A revisit on tests for homogeneity of the risk difference

Lipsitz et al. (1998, Biometrics 54, 148-160) discussed testing the homogeneity of the risk difference for a series of 2 x 2 tables. They proposed and evaluated several weighted test statistics, including the commonly used weighted least squares test statistic. Here we suggest various important improvements on these test statistics. First, we propose using the one-sided analogues of the test procedures proposed by Lipsitz et al. because we should only reject the null hypothesis of homogeneity when the variation of the estimated risk differences between centers is large. Second, we generalize their study by redesigning the simulations to include the situations considered by Lipsitz et al. (1998) as special cases. Third, we consider a logarithmic transformation of the weighted least squares test statistic to improve the normal approximation of its sampling distribution. On the basis of Monte Carlo simulations, we note that, as long as the mean treatment group size per table is moderate or large (> or = 16), this simple test statistic, in conjunction with the commonly used adjustment procedure for sparse data, can be useful when the number of 2 x 2 tables is small or moderate (< or = 32). In these situations, in fact, we find that our proposed method generally outperforms all the statistics considered by Lipsitz et al. Finally, we include a general guideline about which test statistic should be used in a variety of situations.     

Differential recognition of response elements determines target gene specificity for p53 and p63

p63 is a member of the p53 tumor suppressor gene family, which regulates downstream target gene expression by binding to sequence-specific response elements similar to those of p53. By using oligonucleotide expression microarray analysis and analyzing the promoters of p63-induced genes, we have identified novel p63-specific response elements (p63-REs) in the promoter regions of EVPL and SMARCD3. These p63-REs exhibit characteristic differences from the canonical p53-RE (RRRCWWGYYY) in both the core-binding element (CWWG) as well as the RRR and/or YYY stretches. Luciferase assays on mutagenized promoter constructs followed by electromobility shift analysis showed that p53 preferentially activates and binds to the RRRCATGYYY sequence, whereas p63 preferentially activates RRRCGTGYYY. Whereas EVPL protein is highly expressed in epithelial cells of the skin and pharynx in the p63+/+ mouse, it is undetectable in these tissues in the p63-/- mouse. Our results indicate that p63 can regulate expression of specific target genes such as those involved in skin, limb, and craniofacial development by preferentially activating distinct p63-specific response elements.     

Interactions among IQGAP1, Cdc42, and the cadherin/catenin protein complex regulate Sertoli-germ cell adherens junction dynamics in the testis

The movement of developing germ cells across the seminiferous epithelium during spermatogenesis involves extensive adherens junction (AJ) restructuring between Sertoli cells, as well as between Sertoli and germ cells. In this report, we show that the intricate interactions between Cdc42 (a Rho family protein of Mr approximately 23 kDa originally identified in membranes of human platelets and placenta, and is the homolog of CDC42Sc, which is known to regulate of bud-site assembly in Saccharomyces cerevisiae) and its effector, IQ motif containing GTPase activating protein (IQGAP1, Mr approximately 189 kDa, it is also an actin-binding protein known to interact with Cdc42 and Rac1 GTPases), regulate Sertoli-germ cell, but not Sertoli-Sertoli cell, AJ dynamics. Using testis lysates for immunoprecipitation (IP), IQGAP1 was shown to associate with E-cadherin, N-cadherin, and beta-catenin (but not beta1-integrin and nectin-2), as well as with actin and vimentin (but not alpha-tubulin). Moreover, IQGAP1 was found to localize to the periphery of both Sertoli and germ cells in the seminiferous epithelium, at sites of cell-cell contacts. Using fluorescent microscopy with dual fluorescent probes, IQGAP1 was found to co-localize, at least in part, with N-cadherin in the seminiferous epithelium consistent with their localization at the basal and apical ES. Using Sertoli-germ cell cocultures, it was demonstrated that AJ assembly associated with a transient induction of Cdc42 and IQGAP1, which was not found when Sertoli cells were cultured alone. Lastly, a shift in the interactions of Cdc42, IQGAP1, beta-catenin, and N-cadherin was detected in Sertoli-germ cell cocultures using an Ca2+-induced AJ disruption model, which was used to examine AJ disassembly and its reassembly. In the presence of Ca2+, IQGAP1 bound preferentially to Cdc42 rather than to beta-catenin. However, when Ca2+ was depleted from cocultures using EGTA, a Ca2+ chelating agent, IQGAP1 lost its affinity for Cdc42 and became tightly associated with beta-catenin, destabilizing cadherin-mediated AJs between Sertoli and germ cells. Yet this shift of protein-protein interaction was not detected in Sertoli cells cultured alone. These results illustrate that the interactions among IQGAP1, Cdc42, and beta-catenin are crucial to the regulation of Sertoli-germ cell, but not Sertoli-Sertoli cell, AJ dynamics in the seminiferous epithelium.     

Open and closed conformation of the E. coli purine nucleoside phosphorylase active center and implications for the catalytic mechanism.

The crystal structure of the ternary complex of hexameric purine nucleoside phosphorylase (PNP) from Escherichia coli with formycin A derivatives and phosphate or sulphate ions is determined at 2.0 A resolution. The hexamer is found as a trimer of unsymmetric dimers, which are formed by pairs of monomers with active sites in different conformations. The conformational difference stems from a flexible helix (H8: 214-236), which is continuous in one conformer, and segmented in the other. With the continuous helix, the entry into the active site pocket is wide open, and the ligands are bound only loosely ("open" or "loose binding" conformation). By segmentation of the helix (H8: 214-219 and H8': 223-236, separated by a gamma-turn), the entry into the active site is partially closed, the pocket is narrowed and the ligands are bound much more tightly ("closed" or "tight binding" conformation). Furthermore, the side-chain of Arg217 is carried by the moving helix into the active site. This residue, conserved in all homologous PNPs, plays an important role in the proposed catalytic mechanism. In this mechanism, substrate binding takes place in the open, and and the catalytic action occurs in the closed conformation. Catalytic action involves protonation of the purine base at position N7 by the side-chain of Asp204, which is initially in the acid form. The proton transfer is triggered by the Arg217 side-chain which is moved by the conformation change into hydrogen bond distance to Asp204. The mechanism explains the broad specificity of E. coli PNP, which allows 6-amino as well as 6-oxo-nucleosides as substrates. The observation of two kinds of binding sites is fully in line with solution experiments which independently observe strong and weak binding sites for phosphate as well as for the nucleoside inhibitor.