Towards the mechanism and comparative effect of diphenyl diselenide, diphenyl ditelluride and ebselen under various pathophysiological conditions in rat's kidney preparation

As an extension of our previous work we not only evaluated the relationship between acidosis and lipid peroxidation in rat's kidney homogenate, but also determined for the first time the potential anti-oxidant activity of diphenyl diselenide, diphenyl ditelluride and ebselen at a range of pH values (7.4–5.4). Because of the pH dependency of iron redox cycling, pH and iron need to be well controlled and for the reason we tested a number of pH values (from 7.4 to 5.4) to get a closer idea about the role of iron under various pathological conditions. Acidosis increased rate of lipid peroxidation in the absence Fe (II) in kidney homogenates especially at pH 5.4. This higher extent of lipid peroxidation can be explained by; the mobilized iron which may come from reserves where it is weakly bound. Addition of iron (Fe) chelator desferoxamine (DFO) to reaction medium completely inhibited the peroxidation processes at all studied pH values including acidic values (5.8–5.4). In the presence of Fe (II) acidosis also enhanced detrimental effect of Fe (II) especially at pH (6.4–5.4). Diphenyl diselenide significantly protected lipid peroxidation at all studied pH values, while ebselen offered only a small statistically non-significant protection. The highest anti-oxidant potency was observed for diphenyl ditelluride. These differences in potencies were explained by the mode of action of these compounds using their catalytic anti-oxidant cycles. However, changing the pH of the reaction medium did not alter the anti-oxidant activity of the tested compounds. This study provides evidence for acidosis catalyzed oxidative stress in kidney homogenate and for the first time anti-oxidant potential of diphenyl diselenide and diphenyl ditelluride not only at physiological pH but also at a range of acidic values.     

Non-histone protein methylation in Trypanosoma cruzi epimastigotes

Post-translational methylation of proteins, which occurs in arginines and lysines, modulates several biological processes at different levels of cell signaling. Recently, methylation has been demonstrated in the regulation beyond histones, for example, in the dynamics of protein-protein and protein-nucleic acid interactions. However, the presence and role of non-histone methylation in Trypanosoma cruzi, the etiologic agent of Chagas disease, has not yet been elucidated. Here, we applied mass spectrometry-based-proteomics (LC-MS/MS) to profile the methylproteome of T. cruzi epimastigotes, describing a total of 1252 methyl sites in 824 proteins. Functional enrichment and protein-protein interaction analysis show that protein methylation impacts important biological processes of the parasite, such as translation, RNA and DNA binding, amino acid, and carbohydrate metabolism. In addition, 171 of the methylated proteins were previously reported to bear phosphorylation sites in T. cruzi, including flagellar proteins and RNA binding proteins, indicating that there may be an interplay between these different modifications in non-histone proteins. Our results show that a broad spectrum of functions is affected by methylation in T. cruzi, indicating its potential to impact important processes in the biology of the parasite and other trypanosomes.     

Plant regeneration from stem and petiole-derived callus ofHumulus lupulus L. (hop) clone Bragança and var. Brewer’s Gold

Summary Plant regeneration was achieved from both a spontaneous clone (Bragan?a) and Brewer's Gold variety ofHumulus lupulus. The results obtained for these two different genotypes were compared. The organogenic ability of petiole and stem segments was tested on three different basal media supplemented with 0.025 mg (0.14 μM) indole-3-acetic acid/L and 2 mg (8.87 μM) 6-benzylaminopurine (N⁶-benzyladenine)/L. These conditions induced rather heterogeneous responses, which depended mainly on the explant source and the genotype. Because of the high organogenic competence revealed by the spontaneous clone on modified Murashige and Skoog medium, several hormones in different combinations were tested to optimize conditions for adventitious shoot regeneration in this clone. The best relation between the average shoot number/callus and the regeneration rate was achieved with 0.025 mg (0.14 μM) indole-3-acetic acid/L and 2 mg (8.87 μM) 6-benzylaminopurine/L or with 0.02 mg (0.11 μM) indole-3-acetic acid/L and 1.5 mg (6.97 μM) kinetin/L, which enabled 72 and 59% of regeneration, respectively. The regenerated plantlets could be acclimatized with 90% success.     

Isodicentric Y chromosome: cytogenetic,molecular and clinical studies and review of the literature

Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.     

Effect of end-stage renal disease and diabetes on zinc and copper status

The aim of this study was to compare the nutritional status of zinc and copper in patients with and without diabetes submitted to chronic hemodialysis. Thirty-three patients with type 2 diabetes (DM group), 30 nondiabetic patients (NDM group), and 20 healthy individuals (control group) were studied. Plasma, erythrocyte, and urinary zinc and plasma copper were obtained from atomic absorption spectrophotometry and ceruloplasmin by immunonephelometry. The anthropometric parameters were similar among the groups. Plasma zinc was lower and erythrocyte zinc was higher in the DM and NDM groups in relation to the control group. No difference in urinary zinc was observed comparing the groups. Plasma copper was higher in the DM group when compared to the NDM and control groups. Ceruloplasmin was similar in the three groups. Serum urea was a positive independent determinant of plasma zinc concentrations. The determinants of erythrocyte zinc were MAMC midarm nuscle circumference and Kt/V dialysis adequacy. The determinants of plasma copper concentration were serum creatinine and serum glucose. The results of this study demonstrate an alteration in the distribution of zinc of patients with chronic kidney disease (CKD) independently of the presence of DM. Also, the status of copper seems not to be influenced by CKD, but only by the metabolic derangements associated with diabetes.     

Reengineering Rate-Limiting, Millisecond Enzyme Motions by Introduction of an Unnatural Amino Acid

Rate-limiting millisecond motions in wild-type (WT) Ribonuclease A (RNase A) are modulated by histidine 48. Here, we incorporate an unnatural amino acid, thia-methylimidazole, at this site (H48C-4MI) to investigate the effects of a single residue on protein motions over multiple timescales and on enzyme catalytic turnover. Molecular dynamics simulations reveal that H48C-4MI retains some crucial WT-like hydrogen bonding interactions but the extent of protein-wide correlated motions in the nanosecond regime is decreased relative to WT. NMR Carr-Purcell-Meiboom-Gill relaxation dispersion experiments demonstrate that millisecond conformational motions in H48C-4MI are present over a similar pH range compared to WT. Furthermore, incorporation of this nonnatural amino acid allows retention of WT-like catalytic activity over the full pH range. These studies demonstrate that the complexity of the protein energy landscape during the catalytic cycle can be maintained using unnatural amino acids, which may prove useful in enzyme design efforts.     

The Galactose-Binding Lectin Isolated from Vatairea macrocarpa Seeds Enhances the Effect of Antibiotics Against Staphylococcus aureus–Resistant Strain

Probiotics and Antimicrobial Proteins - The use of natural products together with standard antimicrobial drugs has recently received more attention as a strategy to combat infectious diseases...