Kinetic, thermodynamic and statistical studies on the inhibition of adenosine deaminase by aspirin and diclofenac

The kinetic and thermodynamic effects of aspirin and diclofenac on the activity of adenosine deaminase (ADA) were studied in 50 mM phosphate buffer pH = 7.5 at 27 and 37 degrees C, using UV-Vis spectrophotometry and isothermal titration calorimetry (ITC). Aspirin exhibits competitive inhibition at 27 and 37 degrees C and the inhibition constants are 42.8 and 96.8 microM respectively, using spectrophotometry. Diclofenac shows competitive behavior at 27 degrees C and uncompetitive at 37 degrees C with inhibition constants of 56.4 and 30.0 microM, at respectively. The binding constant and enthalpy of binding, at 27 degrees C are 45 microM, - 64.5 kJ/mol and 61 microM, - 34.5 kJ/mol for aspirin and diclofenac. Thermodynamic data revealed that the binding process for these ADA inhibitors is enthalpy driven. QSAR studies by principal component analysis implemented in SPSS show that the large, polar, planar, and aromatic nucleoside and small, aromatic and polar non-nucleoside molecules have lower inhibition constants.     

Computational insights into pH-dependence of structure and dynamics of pyrazinamidase: A comparison of wild type and mutants

The mycobacterial enzyme pyrazinamidase (PZase) is the target of key tuberculosis drug, pyrazinamide. Mutations in PZase cause drug resistance. Herein, three point mutations, W68G, L85P, and V155G, were investigated through over 8 µs of molecular dynamics simulations coupled with essential dynamics and binding pocket analysis at neutral (pH = 7) and acidic (pH = 4) ambient conditions. The 51-71 flap region exhibited drastic displacement leading to enlargement of binding cavity, especially at the lower pH. Accessibility of solvent to the active site of the mutant enzymes was also reduced. The protonation of key surface residues at low pH results in more contribution of these residues to structural stability and integrity of the enzyme and reduced interactions with solvent molecules, which acts as a cage, keeping the enzyme together. The observed results suggest a pattern of structural alterations due to point mutations in PZase, which is consistent with other experimental and theoretical investigations and, can be harnessed for drug design purposes.     

A genetic variant in CDKN2A/2B locus was associated with poor prognosis in patients with esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is among the leading causes of cancer related death. Despite of extensive efforts in identifying valid cancer prognostic biomarkers, only a very small number of markers have been identified. Several genetic variants in the 9p21 region have been identified that are associated with the risk of multiple cancers. Here, we explored the association of two genetic variants in the 9p21 region, CDKN2A/B, rs10811661, and rs1333049 for the first time in 273 subjects with, or without ESCC. We observed that the patients with ESCC had a higher frequency of a TT genotype for rs10811661 than individuals in the control group, and this polymorphism was also associated with tumor size. Moreover, a CC genotype for the rs1333049 polymorphism was associated with a reduced overall survival (OS) of patients with ESCC. In particular, patients with a CC (rs1333049) genotype had a significantly shorter OS (CC genotype: 34.5 ± 8.9 months vs. CG+GG: 47.7 ± 5.9 months; p value = 0.03). We have also shown the association of a novel genetic variant in CDKN2B gene with clinical outcome of patients with ESCC. Further investigations are warranted in a larger population to explore the value of emerging markers as a risk stratification marker in ESCC.     

Parallel plumage colour evolution and introgressive hybridization in wheatears

Genetic and phenotypic mosaics, in which various phenotypes and different genomic regions show discordant patterns of species or population divergence, offer unique opportunities to study the role of ancestral and introgressed genetic variation in phenotypic evolution. Here, we investigated the evolution of discordant phenotypic and genetic divergence in a monophyletic clade of four songbird taxa—pied wheatear (O. pleschanka), Cyprus wheatear (Oenanthe cypriaca), and western and eastern subspecies of black‐eared wheatear (O. h. hispanica and O. h. melanoleuca). Phenotypically, black back and neck sides distinguish pied and Cyprus wheatears from the white‐backed/necked black‐eared wheatears. Meanwhile, mitochondrial variation only distinguishes western black‐eared wheatear. In the absence of nuclear genetic data, and given frequent hybridization among eastern black‐eared and pied wheatear, it remains unclear whether introgression is responsible for discordance between mitochondrial divergence patterns and phenotypic similarities, or whether plumage coloration evolved in parallel. Multispecies coalescent analyses of about 20,000 SNPs obtained from RAD data mapped to a draft genome assembly resolve the species tree, provide evidence for the parallel evolution of colour phenotypes and establish western and eastern black‐eared wheatears as independent taxa that should be recognized as full species. The presence of the entire admixture spectrum in the Iranian hybrid zone and the detection of footprints of introgression from pied into eastern black‐eared wheatear beyond the hybrid zone despite strong geographic structure of ancestry proportions furthermore suggest a potential role for introgression in parallel plumage colour evolution. Our results support the importance of standing heterospecific and/or ancestral variation in phenotypic evolution.     

TLR4 and TLR2 expression in biopsy specimens from antral and corporal stomach zones in Helicobacter pylori infections

Background:

It is not yet known which types of Toll-like receptors (TLRs) are most effective in Helicobacter pylori (H. pylori) recognition. It is also not known which gastric zones have the most prominent roles in TLR-mediated bacterial recognition. The aim of this work was to analyze the expression of TLR2 and TLR4 in biopsy specimens from H. pylori-infected patients.

Methods:

Thirty-eight patients with gastrointestinal disorders were divided into four groups in this study. The groups were: (A) H. pylori infection and peptic ulcer (n=15), (B) peptic ulcer only (n=5), (C) H. pylori infection only (n=10) and (D) control, with neither H. pylori infection nor peptic ulcer (n=8). Biopsy specimens from sites of redness or atrophic mucosa from gastric antrum and body in patients with gastritis were collected. RNAs from the antrum and body specimens were isolated. TLR2 and TLR4 mRNA expression was assessed by RT-PCR and quantified as densitometric ratios of TLR2 and TLR4/β-actin mRNA.

Results:

In the antral zones of H. pylori-infected patients (Groups A and C) TLR2 and TLR4 expression was significantly greater than in uninfected patients (Groups B and D) regardless of peptic ulcers (p < 0.05). In the gastric body samples TLR2 expression was significantly greater in Group C (H. pylori infection only) than in Group B (peptic ulcer only) and TLR4 expression was significantly greater in group A (H. pylori infection and peptic ulcer) than in Group B (peptic ulcer only) (p < 0.05). No significant differences in expression of TLR4 and TLR2 were observed between samples from the antrum and body in same groups.

Conclusions:

We conclude that H. pylori infection leads to significant increase in TLR2 and TLR4 molecules expression in antral region related to the control group. Considering the stimulatory effect of H. pylori on TLRs expression in the gastric tissue, we assume that colonization of H. pylori infection might occurs more in the gastric antral region than in the gastric body.Key Words: Helicobacter pylori, Toll-like receptors, TLR4; TLR2, Peptic ulcer     

Relationship among plasma adipokines, insulin and androgens level as well as biochemical glycemic and lipidemic markers with incidence of PCOS in women with normal BMI

Polycystic ovary syndrome (PCOS) is an endocrine disorder in women. Omentin-1 and vaspin are secretary adipokines that are produced by the visceral adipose tissue. These levels change in obese women with PCOS. The aim of this study is to investigate whether omentin and vaspin levels change in nonobese PCOS subjects. This study is a cross-sectional case control study in which 39 women with PCOS were picked out for this study. The inclusion criteria were based on the Rotterdam 2003 diagnostic criteria. The control group consisted of 39 women with normal pelvic sonographic reports having regular menstruation and showing no signs of infertility. The fasting plasma glucose (FPG), triglyceride (TG), Chol, and high-density lipoprotein cholesterol (HDL-C), insulin, testosterone, omentin and vaspin were measured by the enzymatic methods. The differences within these groups were calculated by the un-paired t-test and the Mann-Whitney test. The results from this study show a significant increase in the amount of insulin, testosterone, homeostasis model assessments for insulin resistance, TG and lower HDL in the patient group. No significant differences were seen in omentin, vaspin, FPG, Cho, low-density lipoprotein, very low-density lipoprotein cholesterol, blood urea nitrogen, Cr and homeostasis model assessments for B cell function levels between groups. Results show that PCOS is not a determinant of decreased omentin and vaspin plasma levels and those high androgen level and insulin resistances are warning signs of PCOS.