Comparative proteomic analysis of Streptococcus suis biofilms and planktonic cells that identified biofilm infection-related immunogenic proteins

Streptococcus suis (SS) is a zoonotic pathogen that causes severe disease symptoms in pigs and humans. Biofilms of SS bind to extracellular matrix proteins in both endothelial and epithelial cells and cause persistent infections. In this study, the differences in the protein expression profiles of SS grown either as planktonic cells or biofilms were identified using comparative proteomic analysis. The results revealed the existence of 13 proteins of varying amounts, among which six were upregulated and seven were downregulated in the Streptococcus biofilm compared with the planktonic controls. The convalescent serum from mini-pig, challenged with SS, was applied in a Western blot assay to visualize all proteins from the biofilm that were grown in vitro and separated by two-dimensional gel electrophoresis. A total of 10 immunoreactive protein spots corresponding to nine unique proteins were identified by MALDI-TOF/TOF-MS. Of these nine proteins, five (Manganese-dependent superoxide dismutase, UDP-N-acetylglucosamine 1-carboxyvinyltransferase, ornithine carbamoyltransferase, phosphoglycerate kinase, Hypothetical protein SSU05_0403) had no previously reported immunogenic properties in SS to our knowledge. The remaining four immunogenic proteins (glyceraldehyde-3-phosphate dehydrogenase, hemolysin, pyruvate dehydrogenase and DnaK) were identified under both planktonic and biofilm growth conditions. In conclusion, the protein expression pattern of SS, grown as biofilm, was different from the SS grown as planktonic cells. These five immunogenic proteins that were specific to SS biofilm cells may potentially be targeted as vaccine candidates to protect against SS biofilm infections. The four proteins common to both biofilm and planktonic cells can be targeted as vaccine candidates to protect against both biofilm and acute infections.     

Correlation between CAT polymorphism and susceptibility to DMAc-induced abnormal liver function: a case-control study of Chinese population

Context: Acute or chronic exposure of N,N-dimethylacetamide (DMAc) is responsible for abnormal liver function. It appears that DMAc is mainly metabolized by cytochrome P450 in the liver and thereby produces reactive oxygen species (ROS). The elimination of ROS and the repairing of ROS-induced DNA damage are relevant to the ultimate toxicity of DMAc.

Objective: To investigate whether the polymorphisms in the CAT (rs564250, rs769214 and rs7943316), hOGG1 (rs2072668 and rs159153) and XRCC1 (rs25487 and rs1799782) genes are associated with susceptibility to DMAc-induced abnormal liver function in Chinese population.

Methods: Samples were obtained from 108 workers with DMAc-induced abnormal liver function and 108 workers with normal liver function.

Results: Subjects with the CAT rs769214 GA/GG genotypes had a reducing risk of abnormal liver function, which was more evident in the subgroups exposed to DMAc?<10?years, exposed to DMAc?<5?mg/m³, never smoked and never drank.

Conclusions: CAT rs769214 (-844?G?>?A) polymorphism may be associated with DMAc-induced abnormal liver function in Chinese population.     

A High-Throughput Approach for Identification of Novel General Anesthetics

Anesthetic development has been a largely empirical process. Recently, we described a GABAergic mimetic model system for anesthetic binding, based on apoferritin and an environment-sensitive fluorescent probe. Here, a competition assay based on 1-aminoanthracene and apoferritin has been taken to a high throughput screening level, and validated using the LOPAC¹²⁸⁰ library of drug-like compounds. A raw hit rate of ∼15% was reduced through the use of computational filters to yield an overall hit rate of ∼1%. These hits were validated using isothermal titration calorimetry. The success of this initial screen and computational triage provides feasibility to undergo a large scale campaign to discover novel general anesthetics.     

Zn2+ mediates ischemia-induced impairment of the ubiquitin-proteasome system in the rat hippocampus

Deposition of ubiquitinated protein aggregates is a hallmark of neurodegeneration in both acute neural injuries, such as stroke, and chronic conditions, such as Parkinson's disease, but the underlying mechanisms are poorly understood. In the present study, we examined the role of Zn²⁺ in ischemia-induced impairment of the ubiquitin-proteasome system in the CA1 region of rat hippocampus after transient global ischemia. We found that scavenging endogenous Zn²⁺ reduced ischemia-induced ubiquitin conjugation and free ubiquitin depletion. Furthermore, exposure to zinc chloride increased ubiquitination and inhibited proteasomal enzyme activity in cultured hippocampal neurons in a concentration- and time-dependent manner. Further studies of the underlying mechanisms showed that Zn²⁺-induced ubiquitination required p38 activation. These findings indicate that alterations in Zn²⁺ homeostasis impair the protein degradation pathway.