Rapid and sensitive assay for the phytotoxin rhizobitoxine.

Rhizobitoxine is a phytotoxin synthesized by some strains of the legume symbiont genus Bradyrhizobium and the plant pathogen Pseudomonas andropogonis. We demonstrate here a new enzymatic assay which is 100-fold more sensitive than previous assays and can detect as little as 1.0 pmol of rhizobitoxine. The assay is based on the inhibition of Salmonella typhimurium beta-cystathionase by rhizobitoxine. Interestingly, beta-cystathionase from Bradyrhizobium japonicum is insensitive to rhizobitoxine at concentrations lower than 75 microM.     

Supramolecular aggregation/disaggregation-based molecular sensing: a review focused on investigations from China

Supramolecular aggregation and disaggregation induced by external stimuli can impact the optical or electrical signals of the aggregates/constituting units (receptors). Therefore, manipulating supramolecular aggregation/disaggregation has recently been employed to construct novel and promising photoluminescence (PL)‐based sensing and recognition systems. The sensing systems were capable of substantially enhancing the sensitivity, relying on cooperative interactions occurring in the assembly/disassembly processes (mostly operating in emission turned‐on or emission‐enhanced mode). This review focuses mainly on recent advances in the new emerging PL‐based sensing platforms, based on manipulating the behaviours of supramolecular aggregation/disaggregation, including aggregation‐induced emission (AIE), metallophilic interactions‐related sensing (metallophilic interactions‐induced aggregation/disaggregation), metal coordination polymers‐related sensing, and other sensing systems involving supramolecular aggregation/disaggregation. In particular, those sensing systems developed by scientists in China are summarized and highlighted. Copyright © 2011 John Wiley & Sons, Ltd.     

Hemoglobin Levels and Weaning Outcome of Mechanical Ventilation in Difficult-To-Wean Patients: A Retrospective Cohort Study

Introduction

The effect of hemoglobin levels on the weaning outcomes of mechanically ventilated patients remains under debate, particularly for the patients with difficult weaning. This study aims to evaluate the effect of hemoglobin levels on weaning outcomes in difficult-to-wean patients.

Methods

This retrospective cohort study was conducted in a university-affiliated teaching hospital in Taiwan. Patients who fulfilled the criteria of difficult weaning were enrolled. Medical records were reviewed to obtain data on hemograms, biochemistry tests, transfusion records, comorbidities and weaning outcome. The association between hemoglobin levels and 30-day weaning outcomes was evaluated using a logistic regression model.

Results

A total of 751 patients received mechanical ventilation during the study period, 138 of whom fulfilled the criteria of difficult weaning. Compared with the patients whose hemoglobin was <8 g/dL, those with higher hemoglobin levels were more likely to be successfully weaned (odds ratio [OR], 3.69; 95% CI, 1.22–11.15 for hemoglobin 8–10 g/dL and OR, 4.16, 95% CI, 1.30–13.29 for hemoglobin >10 g/dL). Multivariate analysis showed that the odds ratio for weaning success remained significant for hemoglobin levels of 8–10 g/dL (adjusted OR, 3.3; 95% CI, 1.07–10.15) with borderline significance for hemoglobin level > 10 g/dL (adjusted OR, 2.95, 95% CI, 0.88–9.96).

Conclusions

Hemoglobin level is independently associated with weaning outcome in difficult-to-wean patients. Further studies are needed to evaluate whether a restrictive transfusion trigger for acute critical illness is also appropriate for such patients.     

MicroRNA‐760 Inhibits Doxorubicin Resistance in Hepatocellular Carcinoma through Regulating Notch1/Hes1‐PTEN/Akt Signaling Pathway

Accumulating studies have suggested that microRNA‐760 (miR‐760) plays an important role in chemoresistance of various cancer cells. However, whether miR‐760 regulates the chemoresistance of hepatocellular carcinoma (HCC) remains unclear. In this study, we found that miR‐760 was decreased in HCC cell lines, and doxorubicin (Dox) treatment significantly decreased miR‐760 expression in HCC cells. Overexpression of miR‐760 sensitized HCC cells to Dox‐induced cytotoxicity and apoptosis, whereas miR‐760 inhibition showed the opposite effects. Notch1 was predicted as a target gene of miR‐760. miR‐760 negatively regulated Notch1 expression and Notch1/Hes1 signaling. Overexpression of miR‐760 increased PTEN expression and decreased the phosphorylation of Akt. Activation of Notch signaling significantly reversed the inhibitory effect of miR‐760 on Dox‐resistance and abrogated the effect of miR‐760 on the PTEN/Akt signaling pathway in HCC cells. Overall, our results demonstrate that miR‐760 inhibits Dox‐resistance in HCC cells through inhibiting Notch1 and promoting PTEN expression.     

Sciadonic acid modulates prostaglandin E2 production by epithelial cells during infection with C. albicans and C. dubliniensis

Candida albicans is an important opportunistic pathogen in humans. During infection, arachidonic acid (ω6) is released from host phospholipids, leading to the production of host and yeast derived prostaglandin E(2) (PGE(2)). This stimulates yeast hyphal formation, is immunomodulatory and causes cell damage during infection. Although supplementation of mammalian cells with ω3 fatty acids has received attention due to their immunomodulatory and anti-inflammatory activities, increased production of ω3 fatty acid metabolites could lower the host's ability to combat infections. Since mammalian cells cannot produce PGE(2) from sciadonic acid (SA), a non-methylene interrupted ω6 fatty acid (NMIFA), supplementation of cells with SA may decrease the production of PGE(2) without increasing levels of ω3 fatty acid metabolites. Our study evaluated PGE(2) production by SA supplemented epithelial cells in response to Candida albicans and C. dubliniensis. We show that PGE(2) production during infection can be modulated by incorporation of SA into host lipids and that this does not influence the levels of ω3 fatty acids in the epithelial cells.     

从酵母中提取谷胱甘肽的初步研究

考察了不同提取方法对从酵母中提取谷胱甘肽（ＧＳＨ）的影响,热水抽提由于其提取收率高（９０％）,耗时短（１０ｍｉｎ）经济性强而明显优于其它提取方法,对７３２阳离子交换树脂纯化ＧＳＨ进行了初步研究,主要研究了树脂颗粒大小对提纯ＧＳＨ的影响,采用６０～８０目的树脂,ＧＳＨ收率为５７．６％,虽然比８０目以上的树脂低１０％但前者操作作所需时间只有后者的１／３。     

A rare protein fluorescence behavior where the emission is dominated by tyrosine: case of the 33-kDa protein from spinach photosystem II

An abnormal fluorescence emission of protein was observed in the 33-kDa protein which is one component of the three extrinsic proteins in spinach photosystem II particle (PS II). This protein contains one tryptophan and eight tyrosine residues, belonging to a "B type protein". It was found that the 33-kDa protein fluorescence is very different from most B type proteins containing both tryptophan and tyrosine residues. For most B type proteins studied so far, the fluorescence emission is dominated by the tryptophan emission, with the tyrosine emission hardly being detected when excited at 280 nm. However, for the present 33-kDa protein, both tyrosine and tryptophan fluorescence emissions were observed, the fluorescence emission being dominated by the tyrosine residue emission upon a 280 nm excitation. The maximum emission wavelength of the 33-kDa protein tryptophan fluorescence was at 317 nm, indicating that the single tryptophan residue is buried in a very strong hydrophobic region. Such a strong hydrophobic environment is rarely observed in proteins when using tryptophan fluorescence experiments. All parameters of the protein tryptophan fluorescence such as quantum yield, fluorescence decay, and absorption spectrum including the fourth derivative spectrum were explored both in the native and pressure-denatured forms.     

Enrichment and characterization of an anaerobic cellulolytic microbial consortium SQD-1.1 from mangrove soil

Enrichment of microbial consortia provides an approach to simulate and investigate microbial communities in natural environments. In this study, a cellulolytic microbial consortium SQD-1.1 was enriched from mangrove soil of Qinglan port (Hainan, China) by 27 times continuous subcultivation under anaerobic static conditions. The consortium could completely degrade 0.2 % (w/v) filter paper within 3 days and utilized it as the sole carbon source. PCR-denaturing gradient gel electrophoresis analysis revealed a stable microbial community structure in the incubation process of 10 days and in the procedure of subcultivation. Twenty-four operational taxonomic units belonging to seven phyla were obtained from the full-length 16S rRNA gene library. Five clones, closest related to the genera Alkaliflexus, Clostridium, Alistipes, Spirochaeta, and Trichococcus, were the predominant ones. Among them, M117, phylogeneticly showing high similarity (16S rRNA gene identity, 95.3 %) with the cellulolytic anaerobic bacterium Clostridium straminisolvens CSK1^T, was the potential key cellulolytic bacterium. Using the plate cultivation method, 12 strains, including one potential new species and four potential new species of new genera, were isolated. The strain P2, corresponding to the most frequently detected clone (M05) in the 16S rRNA gene library, showed both CMCase and xylanase activity and may be another important cellulolytic bacterium. The findings of cellulase activity in cell pellet and cohesion and dockerin domains in metagenome data further suggested the potential of utilization of cellulosomes by the consortium to degrade cellulose. Consortium SQD-1.1 provides a candidate for investigating the mechanism of cellulose degradation under anoxic conditions in natural environments.