Effect of quercetin and its glucuronide metabolite upon 6-hydroxydopamine-induced oxidative damage in Neuro-2a cells

Quercetin is ubiquitously distributed in plant foods. This antioxidative polyphenol is mostly converted to conjugated metabolites in the body. Parkinson disease (PD) has been suggested to be related to oxidative stress derived from abnormal dopaminergic activity. We evaluated if dietary quercetin contributes to the antioxidant network in the central nervous system from the viewpoint of PD prevention. A neurotoxin, 6-hydroxydopamine (6-OHDA), was used as a model of PD. 6-OHDA-induced H?O? production and cell death in mouse neuroblastoma, Neuro-2a. Quercetin aglycone suppressed 6-OHDA-induced H?O? production and cell death, although aglycone itself reduced cell viability at higher concentration. Quercetin 3-O-β-D-glucuronide (Q3GA), which is an antioxidative metabolite of dietary quercetin, was little incorporated into the cell resulting in neither suppression of 6-OHDA-induced cell death nor reduction of cell viability. Q3GA was found to be deconjugated to quercetin by microglial MG-6 cells. These results indicate that quercetin metabolites should be converted to their aglycone to exert preventive effect on damage to neuronal cells.     

Effect of Methyl Substitution on Microbial Degradation of Linear Styrene Dimers by Two Soil Bacteria

The microbial degradation of 10 linear unsaturated dimers (I to IV) prepared from styrene and o-, m-, or p-methylstyrene was investigated with two soil bacteria, Alcaligenes sp. strain 559 and Pseudomonas sp. strain 419. The two strains decomposed styrene dimer I and all styrene-methylstyrene codimers II and III, but methylstyrene homodimers IV remained intact. The degradation rates of codimers II and III of o- and m-methylstyrenes were found to depend on both their structure and the strain used; i.e., Alcaligenes sp. strain 559 decomposed III faster than II, whereas the reverse order (II > III) was obtained with Pseudomonas sp. strain 419. In biodegradation by the former strain, the codimers were degraded faster in the presence of styrene dimer I than in its absence, but no such effect of dimer I was observed with the latter.     

Persistent replication of a hepatitis C virus genotype 1b‐based chimeric clone carrying E1, E2 and p6 regions from GB virus B in a New World monkey

The development of effective hepatitis C virus (HCV) vaccines is essential for the prevention of further HCV dissemination, especially in developing countries. Therefore the aim of this study is to establish a feasible and immunocompetent surrogate animal model of HCV infection that will help in evaluation of the protective efficacy of newly developing HCV vaccine candidates. To circumvent the narrow host range of HCV, an HCV genotype 1b‐based chimeric clone carrying E1, E2 and p6 regions from GB virus B (GBV‐B), which is closely related to HCV, was generated. The chimera between HCV and GBV‐B, named HCV/G, replicated more efficiently as compared with the HCV clone in primary marmoset hepatocytes. Furthermore, it was found that the chimera persistently replicated in a tamarin for more than 2 years after intrahepatic inoculation of the chimeric RNA. Although relatively low (<200 copies/mL), the viral RNA loads in plasma were detectable intermittently during the observation period. Of note, the chimeric RNA was found in the pellet fraction obtained by ultracentrifugation of the plasma at 73 weeks, indicating production of the chimeric virus. Our results will help establish a novel non‐human primate model for HCV infection on the basis of the HCV/G chimera in the major framework of the HCV genome.     

Species distribution,virulence factors and antimicrobial resistance of Acinetobacter spp. isolates from dogs and cats: a preliminary study

In this study, the prevalence of virulence factors and antimicrobial resistance among 67 Acinetobacter spp. isolates, consisting of 21 Acinetobacter baumannii and 46 non‐baumannii Acinetobacter obtained from companion animals, was investigated. PCR analysis showed that the most prevalent virulence gene was afa/draBC (29.9%), followed by papC (22.4%) and cvaC (20.9%). Antimicrobial susceptibility testing revealed that resistance to gentamicin (14.9%) and ciprofloxacin (11.9%) was relatively prevalent. Five gentamicin‐ and/or ciprofloxacin‐resistant A. baumannii strains were assigned to ST25, ST149, ST164, ST203 and ST1198. All ciprofloxacin‐resistant isolates harbored point mutations in gyrA and/or parC. To the best of our knowledge, this is the first report of preliminary monitoring of animal‐origin Acinetobacter spp. in Japan.

     

Amorphous Silica-Promoted Lysine Dimerization: a Thermodynamic Prediction

It has long been suggested that mineral surfaces played a crucial role in the abiotic polymerization of amino acids that preceded the origin of life. Nevertheless, it remains unclear where the prebiotic process took place on the primitive Earth, because the amino acid–mineral interaction and its dependence on environmental conditions have yet to be understood adequately. Here we examined experimentally the adsorption of L-lysine (Lys) and its dimer (LysLys) on amorphous silica over a wide range of pH, ionic strength, adsorbate concentration, and the solid/water ratio, and determined the reaction stoichiometries and the equilibrium constants based on the extended triple-layer model (ETLM). The retrieved ETLM parameters were then used, in combination with the equilibrium constant for the peptide bond formation in bulk water, to calculate the Lys–LysLys equilibrium in the presence of amorphous silica under various aqueous conditions. Results showed that the silica surface favors Lys dimerization, and the influence varies greatly with changing environmental parameters. At slightly alkaline pH (pH 9) in the presence of a dilute NaCl (1 mM), the thermodynamically attainable LysLys from 0.1 mM Lys reached a concentration around 50 times larger than that calculated without silica. Because of the versatility of the ETLM, which has been applied to describe a wide variety of biomolecule–mineral interactions, future experiments with the reported methodology are expected to provide a significant constraint on the plausible geological settings for the condensation of monomers to polymers, and the subsequent chemical evolution of life.     

Expression of HIV-1 accessory protein Vif is controlled uniquely to be low and optimal by proteasome degradation

While the Vif protein of human immunodeficiency virus type 1 (HIV-1) is essential for viral replication in non-permissive cells, it is rapidly degraded intracellularly. We have previously suggested that the rapid turn-over of Vif is biologically meaningful to prevent detrimental effects of this protein at high expression levels. We now studied the mechanism of Vif degradation by examining the blocking effect of protease inhibitors in pulse/chase experiments and by monitoring the extent of Vif ubiquitination. The rapid turn-over of Vif could be blocked by proteasome inhibitors, and Vif was highly ubiquitinated. Cytoskeletal Vif was found to be more stable than soluble cytosolic Vif. These degradation characteristics of Vif were cell type-independent and observed in both non-permissive and permissive cells. Characterization of a series of vif deletion mutants showed that amino acids predicted to be important for formation of beta-strand structures (amino acid nos. 63-70 and 86-89) were critical for maintaining a normal expression level of Vif and for viral infectivity. Finally, we performed comparative stability analysis of the four HIV-1 accessory proteins. Vif was unique in its short half-life and in the magnitude of the degradation. Taken together, we conclude that the proteasome degradation of HIV-1 Vif is a virologically important process and crucial for the function of Vif.     

Phase I clinical study of anti-apoptosis protein survivin-derived peptide vaccination for patients with advanced or recurrent urothelial cancer

Survivin, a member of the inhibitor of apoptosis protein family, is expressed in many malignant tumors including urothelial cancer but is hardly detectable in normal, differentiated adult tissues. Previously we reported CD8-positive cytotoxic T-lymphocytes (CTLs) were successfully induced by stimulation with survivin-2B80-88 peptide in vitro. We started a phase I clinical study of survivin-2B80-88 peptide vaccination for advanced urothelial cancer patients to assess the safety and efficacy of this vaccination. Nine patients were received vaccination and were evaluated for immunological evaluation, adverse events, and clinical responses. A total of 46 vaccinations were carried out. There was no severe adverse event. HLA-A24/survivin-2B80-88 peptide tetramer analysis revealed a significant increase in the peptide-specific CTL frequency after the vaccination in five patients. Slight reduction of the tumor volume was observed in one patient. Survivin-2B80-88 peptide-based vaccination is safe and should be further considered for potential immune and clinical efficacy in urothelial cancer patients.