Pharmacological evaluation and preparation of nonsteroidal anti-inflammatory drugs containing an N-Acyl hydrazone subunit

A series of anti-inflammatory derivatives containing an N-acyl hydrazone subunit (4a–e) were synthesized and characterized. Docking studies were performed that suggest that compounds 4a–e bind to cyclooxygenase (COX)-1 and COX-2 isoforms, but with higher affinity for COX-2. The compounds display similar anti-inflammatory activities in vivo, although compound 4c is the most effective compound for inhibiting rat paw edema, with a reduction in the extent of inflammation of 35.9% and 52.8% at 2 and 4 h, respectively. The anti-inflammatory activity of N-acyl hydrazone derivatives was inferior to their respective parent drugs, except for compound 4c after 5 h. Ulcerogenic studies revealed that compounds 4a–e are less gastrotoxic than the respective parent drug. Compounds 4b–e demonstrated mucosal damage comparable to celecoxib. The in vivo analgesic activities of the compounds are higher than the respective parent drug for compounds 4a–b and 4d–e. Compound 4a was more active than dipyrone in reducing acetic-acid-induced abdominal constrictions. Our results indicate that compounds 4a–e are anti-inflammatory and analgesic compounds with reduced gastrotoxicity compared to their respective parent non-steroidal anti-inflammatory drugs.

Expression of α6 integrin subunit in bovine oocyte and its potential role during fertilization

Fertilization in mammals requires the successful completion of a sequence of steps, starting with the transport of gametes in the reproductive tract and ending with sperm-egg membrane fusion to produce a zygote. Although some integrin subunits are known to be associated with the plasma membrane of some mammalian oocytes and spermatozoa, the presence of α6 integrin on bovine oocytes with intact zona pellucida has not been reported. The present study was undertaken to evaluate the expression of α6 integrin subunit in bovine oocyte and to determine if in vitro binding to the zona pellucida and fertilization were affected by treating oocytes with α6 integrin subunit antibody. The α6 integrin subunit was identified on the bovine oocyte by immunocytochemistry. In vitro fertilization was significantly decreased when in vitro matured bovine oocytes were pre-incubated with α6 integrin subunit antibody at concentration 5 and 20 μg/mL, and spermoocyte binding increased. These studies demonstrated the presence of α6 integrin subunit on bovine oocyte, and its importance in fertilization and polyspermy.

Cocaine effects on mouse incentive-learning and human addiction are linked to alpha 2 subunit-containing GABA(A) receptors

Because GABA(A) receptors containing alpha 2 subunits are highly represented in areas of the brain, such as nucleus accumbens (NAcc), frontal cortex, and amygdala, regions intimately involved in signaling motivation and reward, we hypothesized that manipulations of this receptor subtype would influence processing of rewards. Voltage-clamp recordings from NAcc medium spiny neurons of mice with alpha 2 gene deletion showed reduced synaptic GABA(A) receptor-mediated responses. Behaviorally, the deletion abolished cocaine`s ability to potentiate behaviors conditioned to rewards (conditioned reinforcement), and to support behavioral sensitization. In mice with a point mutation in the benzodiazepine binding pocket of alpha 2-GABA(A) receptors (alpha 2H101R), GABAergic neurotransmission in medium spiny neurons was identical to that of WT (i.e., the mutation was silent), but importantly, receptor function was now facilitated by the atypical benzodiazepine Ro 15-4513 (ethyl 8-amido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5-a] [1,4] benzodiazepine-3-carboxylate). In alpha 2H101R, but not WT mice, Ro 15-4513 administered directly into the NAcc-stimulated locomotor activity, and when given systemically and repeatedly, induced behavioral sensitization. These data indicate that activation of alpha 2-GABA(A) receptors (most likely in NAcc) is both necessary and sufficient for behavioral sensitization. Consistent with a role of these receptors in addiction, we found specific markers and haplotypes of the GABRA2 gene to be associated with human cocaine addiction.

Molecular and Electronic Structure of the Peptide Subunit of Geobacter sulfurreducens Conductive Phi from First Principles

The respiration of metal oxides by the bacterium Geobacter sulfurreducens requires the assembly of a small peptide (the GS pilin) into conductive filaments termed pili. We gained insights into the contribution of the GS pilin to the pilus conductivity by developing a homology model and performing molecular dynamics simulations of the pilin peptide in vacuo and in solution. The results were consistent with a predominantly helical peptide containing the conserved a-helix region required for pilin assembly but carrying a short carboxy-terminal random-coiled segment rather than the large globular head of other bacterial pilins. The electronic structure of the pain was also explored from first principles and revealed a biphasic charge distribution along the pilin and a low electronic HOMO-LUMO gap, even in a wet environment. The low electronic band gap was the result of strong electrostatic fields generated by the alignment of the peptide bond dipoles in the pilin's alpha-helix and by charges from ions in solution and amino acids in the protein. The electronic structure also revealed some level of orbital delocalization in regions of the pilin containing aromatic amino acids and in spatial regions of high resonance where the HOMO and LUMO states are, which could provide an optimal environment for the hopping of electrons under thermal fluctuations. Hence, the structural and electronic features of the pilin revealed in these studies support the notion of a pilin peptide environment optimized for electron conduction.

Structural and Functional Insights from the Metagenome of an Acidic Hot Spring Microbial Planktonic Community in the Colombian Andes

A taxonomic and annotated functional description of microbial life was deduced from 53 Mb of metagenomic sequence retrieved from a planktonic fraction of the Neotropical high Andean (3,973 meters above sea level) acidic hot spring El Coquito (EC). A classification of unassembled metagenomic reads using different databases showed a high proportion of Gammaproteobacteria and Alphaproteobacteria (in total read affiliation), and through taxonomic affiliation of 16S rRNA gene fragments we observed the presence of Proteobacteria, micro-algae chloroplast and Firmicutes. Reads mapped against the genomes Acidiphilium cryptum JF-5, Legionella pneumophila str. Corby and Acidithiobacillus caldus revealed the presence of transposase-like sequences, potentially involved in horizontal gene transfer. Functional annotation and hierarchical comparison with different datasets obtained by pyrosequencing in different ecosystems showed that the microbial community also contained extensive DNA repair systems, possibly to cope with ultraviolet radiation at such high altitudes. Analysis of genes involved in the nitrogen cycle indicated the presence of dissimilatory nitrate reduction to N2 (narGHI, nirS, norBCDQ and nosZ), associated with Proteobacteria-like sequences. Genes involved in the sulfur cycle (cysDN, cysNC and aprA) indicated adenylsulfate and sulfite production that were affiliated to several bacterial species. In summary, metagenomic sequence data provided insight regarding the structure and possible functions of this hot spring microbial community, describing some groups potentially involved in the nitrogen and sulfur cycling in this environment. Citation: Jimenez DJ, Andreote FD, Chaves D, Montana JS, Osorio-Forero C, et al. (2012) Structural and Functional Insights from the Metagenome of an Acidic Hot Spring Microbial Planktonic Community in the Colombian Andes. PLoS ONE 7(12): e52069. doi:10.1371/journal.pone.0052069

Echinococcus granulosus Antigen B Structure: Subunit Composition and Oligomeric States

Background: Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states. Methodology/Principal Findings: The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3 >rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability. Conclusions/Significance: For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

Footprints of a trypanosomatid RNA world: pre-small subunit rRNA processing by spliced leader addition trans-splicing

The addition of a capped mini-exon [spliced leader (SL)] through trans-splicing is essential for the maturation of RNA polymerase (pol) II-transcribed polycistronic pre-mRNAs in all members of the Trypanosomatidae family. This process is an inter-molecular splicing reaction that follows the same basic rules of cis-splicing reactions. In this study, we demonstrated that mini-exons were added to precursor ribosomal RNA (pre-rRNA) are transcribed by RNA pol I, including the 5' external transcribed spacer (ETS) region. Additionally, we detected the SL-5' ETS molecule using three distinct methods and located the acceptor site between two known 5' ETS rRNA processing sites (A' and A1) in four different trypanosomatids. Moreover, we detected a polyadenylated 5' ETS upstream of the trans-splicing acceptor site, which also occurs in pre-mRNA trans-splicing. After treatment with an indirect trans-splicing inhibitor (sinefungin), we observed SL-5' ETS decay. However, treatment with 5-fluorouracil (a precursor of RNA synthesis that inhibits the degradation of pre-rRNA) led to the accumulation of SL-5' ETS, suggesting that the molecule may play a role in rRNA degradation. The detection of trans-splicing in these molecules may indicate broad RNA-joining properties, regardless of the polymerase used for transcription.

Cellular Infiltrates and NF kappa B Subunit c-Rel Signaling in Kidney Allografts of Patients With Clinical Operational Tolerance

Background. Nuclear factor kappa B (NF kappa B) plays a potential role in tolerance by orchestrating onset and resolution of inflammation and regulatory T cell differentiation through subunit c-Rel. We characterized cellular infiltrates and expression of NF kappa B1, c-Rel and its upstream regulators phosphatidylinositol 3-kinase/RAC-alpha serine/threonine kinase, in allograft biopsies from patients with spontaneous clinical operational tolerance (COT). Methods. Paraffin-fixed kidney allograft biopsies from 40 patients with COT (n=4), interstitial rejection (IR; n=12), borderline changes (BC; n=12), and long-term allograft function without rejection (NR; n=12) were used in the study. Cellular infiltrates and immunohistochemical expression of key proteins of the NF kappa B pathway were evaluated in the cortical tubulointerstitium and in cellular infiltrates using digital image analysis software. Results were given as mean +/- SEM. Results. Biopsies from patients with COT exhibited a comparable amount of cellular infiltrate to IR, BC, and NR (COT, 191 +/- 81; IR, 291 +/- 62; BC, 178 +/- 45; and NR, 210 +/- 42 cells/mm(2)) but a significantly higher proportion of forkhead box P3-positive cells (COT, 11%+/- 1.7%; IR, 3.5%+/- 0.70%; BC, 3.4%+/- 0.57%; and NR, 3.7%+/- 0.78% of infiltrating cells; P=0.02). c-Rel expression in cellular infiltrates was significantly elevated in IR, BC, and NR when analyzing the number of positive cells per mm(2) (P=0.02) and positive cells per infiltrating cells (P=0.04). In contrast, tubular PI3K and c-Rel expression were significantly higher in IR and BC but not in NR compared with COT (P=0.03 and P=0.006, respectively). With RAC-alpha serine-threonine kinase, similar tendencies were observed (P=0.2). Conclusions. Allografts from COT patients show significant cellular infiltrates but a distinct expression of proteins involved in the NF kappa B pathway and a higher proportion of forkhead box P3-positive cells.

Aniline-1,4-benzoquinone as a model system for the characterization of products from aniline oligomerization in low acidic media

Increase in the pH medium of aniline polymerization is used for giving products of different morphologies, which are often wrongly attributed to PANI chains. Infrared and Raman spectroscopic data, supported by quantum chemical calculations, show that aniline-1,4-benzoquinone (AnBzq) is a model system for the characterization of the products of aniline oligomerization in low acidic media. The Raman spectra excited at different laser lines reveal the bichromophoric nature of AnBzq, whose absorption bands at 550 nm and 440 nm can be attributed to pi-pi* transitions of the delocalized benzoquinone and amino-phenyl moieties, respectively. (C) 2012 Elsevier B.V. All rights reserved.

Peptidomic Analysis of HEK293T Cells: Effect of the Proteasome Inhibitor Epoxomicin on Intracellular Peptides

Peptides derived from cytosolic, mitochondrial, and nuclear proteins have been detected in extracts of animal tissues and cell lines. To test whether the proteasome is involved in their formation, HEK293T cells were treated with epoxomicin (0.2 or 2 mu M) for 1 h and quantitative peptidomics analysis was performed. Altogether, 147 unique peptides were identified by mass spectrometry sequence analysis. Epoxomicin treatment decreased the levels of the majority of intracellular peptides, consistent with inhibition of the proteasome beta-2 and beta-5 subunits. Treatment with the higher concentration of epoxomicin elevated the levels of some peptides. Most of the elevated peptides resulted from cleavages at acidic residues, suggesting that epoxomicin increased the processing of proteins through the beta-1 subunit. Interestingly, some of the peptides that were elevated by the epoxomicin treatment had hydrophobic residues in P1 cleavage sites. Taken together, these findings suggest that, while the proteasome is the major source of intracellular peptides, other peptide-generating mechanisms exist. Because intracellular peptides are likely to perform intracellular functions, studies using proteasome inhibitors need to be interpreted with caution, as it is possible that the effects of these inhibitors are due to a change in the peptide levels rather than inhibition of protein degradation.

The influence of the Pt crystalline surface orientation on the glycerol electro-oxidation in acidic media

We investigated the electrochemical oxidation of glycerol on low-index Pt single crystals in acidic media (H2SO4 and HClO4) by cyclic voltammetry and Fourier Transform Infrared (FTIR) spectroscopy and we verified that this is a surface sensitive reaction. Pt(100) and Pt(110) surface structures favor the breaking of the C-C-C bond at low potentials (say 0.05 V), as seen by the formation of CO, one of the adsorbed residues of the glycerol dissociation, which poisons these surfaces even at high potentials. Pt(111) surface structure does not favor the C-C-C bond breaking at potentials as low as 0.05 V. However, Pt(111) is less poisoned by residues of glycerol dissociation and, for this reason, it is more active for glycerol oxidation than Pt(100) and Pt(110) at low potentials. Carbonyl containing compounds and CO2 were detected as reaction products of the glycerol oxidation on all investigated single-crystal Pt surfaces. The ratio between CO2 and carbonyl containing compounds is clearly much higher for Pt(100) and Pt(110) than for Pt(111). (C) 2012 Elsevier Ltd. All rights reserved.

OSCILLATORY DYNAMICS IN SYSTEMS CONTAINING BROMATE AND 1,4-CYCLOHEXANEDIONE IN ACIDIC MEDIA. I. THE EFFECT OF TEMPERATURE.

OSCILLATORY DYNAMICS IN SYSTEMS CONTAINING BROMATE AND 1,4-CYCLOHEXANEDIONE IN ACIDIC MEDIA. I. THE EFFECT OF TEMPERATURE. We present in this work the influence of temperature on the dynamics of homogeneous chemical systems containing bromate and 1,4-cyclohexanedione (1,4-CHD) in acidic media. In particular, the following systems were studied: bromate/1,4-CHD/acid, bromate/1,4-CHD/ferroin/acid and bromate/1,4-CHD/trisbipyridine ruthenium/acid. Investigations were carried out by means of an electrochemical probe, at five temperatures between 5 and 45 degrees C. Activation energies (E-a) were estimated in different ways for the pre-oscillatory and oscillatory regimes. In any case, the E-a was found to depend on the catalyst, composition and initial concentrations. In addition, it was observed that ferroin and trisbipyridine ruthenium act as catalysts only during the transition between the induction period and oscillatory regime.

Caspase-mediated cleavage of the exosome subunit PM/Scl-75 during apoptosis

Recent studies have implicated the dying cell as a potential reservoir of modified autoantigens that might initiate and drive systemic autoimmunity in susceptible hosts. A number of subunits of the exosome, a complex of 3'→5' exoribonucleases that functions in a variety of cellular processes, are recognized by the so-called anti-PM/Scl autoantibodies, found predominantly in patients suffering from an overlap syndrome of myositis and scleroderma. Here we show that one of these subunits, PM/Scl-75, is cleaved during apoptosis. PM/Scl-75 cleavage is inhibited by several different caspase inhibitors. The analysis of PM/Scl-75 cleavage by recombinant caspase proteins shows that PM/Scl-75 is efficiently cleaved by caspase-1, to a smaller extent by caspase-8, and relatively inefficiently by caspase-3 and caspase-7. Cleavage of the PM/Scl-75 protein occurs in the C-terminal part of the protein at Asp369 (IILD369↓G), and at least a fraction of the resulting N-terminal fragments of PM/Scl-75 remains associated with the exosome. Finally, the implications of PM/Scl-75 cleavage for exosome function and the generation of anti-PM/Scl-75 autoantibodies are discussed.

Effect of low fluoride acidic dentifrices on dental remineralization

This study evaluated the capacity of fluoride acidic dentifrices (pH 4.5) to promote enamel remineralization using a pH cycling model, comparing them with a standard dentifrice (1,100 µgF/g). Enamel blocks had their surface polished and surface hardness determined (SH). Next, they were submitted to subsurface enamel demineralization and to post-demineralization surface hardness analysis. The blocks were divided into 6 experimental groups (n=10): placebo (without F, pH 4.5, negative control), 275, 412, 550, 1,100 µgF/g and a standard dentifrice (positive control). The blocks were submitted to pH cycling for 6 days and treatment with dentifrice slurries twice a day. After pH cycling, surface and cross-sectional hardness were assessed to obtain the percentage of surface hardness recovery (%SHR) and the integrated loss of subsurface hardness (ΔKHN). The results showed that %SHR was similar among acidic dentifrices with 412, 550, 1,100 µgF/g and to the positive control (Tukey's test; p>0.05). For ΔKHN, the acidic dentifrice with 550 µg F/g showed a better performance when compared with the positive control. It can be concluded that acidic dentifrice 550 µgF/g had similar remineralization capacity to that of positive control.

Association of genetic variants in the promoter region of genes encoding p22phox (CYBA) and glutamate cysteine ligase catalytic subunit (GCLC) and renal disease in patients with type 1 diabetes mellitus

Background Oxidative stress is recognized as a major pathogenic factor of cellular damage caused by hyperglycemia. NOX/NADPH oxidases generate reactive oxygen species and NOX1, NOX2 and NOX4 isoforms are expressed in kidney and require association with subunit p22phox (encoded by the CYBA gene). Increased expression of p22phox was described in animal models of diabetic nephropathy. In the opposite direction, glutathione is one of the main endogenous antioxidants whose plasmatic concentrations were reported to be reduced in diabetes patients. The aim of the present investigation was to test whether functional single nucleotide polymorphisms (SNPs) in genes involved in the generation of NADPH-dependent O2•- (-675 T → A in CYBA, unregistered) and in glutathione metabolism (-129 C → T in GCLC [rs17883901] and -65 T → C in GPX3 [rs8177412]) confer susceptibility to renal disease in type 1 diabetes patients. Methods 401 patients were sorted into two groups according to the presence (n = 104) or absence (n = 196) of overt diabetic nephropathy or according to glomerular filtration rate (GFR) estimated by Modification of Diet in Renal Disease (MDRD) equation: ≥ 60 mL (n = 265) or < 60 mL/min/1.73 m2 (n = 136) and were genotyped. Results No differences were found in the frequency of genotypes between diabetic and non-diabetic subjects. The frequency of GFR < 60 mL/min was significantly lower in the group of patients carrying CYBA genotypes T/A+A/A (18.7%) than in the group carrying the T/T genotype (35.3%) (P = 0.0143) and the frequency of GFR < 60 mL/min was significantly higher in the group of patients carrying GCLC genotypes C/T+T/T (47.1%) than in the group carrying the C/C genotype (31.1%) (p = 0.0082). Logistic regression analysis identified the presence of at least one A allele of the CYBA SNP as an independent protection factor against decreased GFR (OR = 0.38, CI95% 0.14-0.88, p = 0.0354) and the presence of at least one T allele of the GCLC rs17883901 SNP as an independent risk factor for decreased GFR (OR = 2.40, CI95% 1.27-4.56, p = 0.0068). Conclusions The functional SNPs CYBA -675 T → A and GCLC rs17883901, probably associated with cellular redox imbalances, modulate the risk for renal disease in the studied population of type 1 diabetes patients and require validation in additional cohorts.