Selective retention of extracellular polymeric substances induced by adsorption to and coprecipitation with ferrihydrite

Recent work shows that microbially-derived compounds constitute a significant fraction of the soil organic matter (OM) pool. These compounds include extracellular polymeric substances (EPS) whose mass can far exceed total microbial cell biomass. Sorption of EPS to soil minerals occurs via adsorption and coprecipitation and contributes to the preservation of OM in the soil environment. Little is known, however, about the sorption mechanisms of EPS and selective retention of different EPS constituents on iron (oxyhydr)oxides, especially during EPS adsorption versus coprecipitation with these reactive soil phases. This study examines how EPS interacts with the ubiquitous soil iron (oxyhydr)oxide ferrihydrite during EPS adsorption and coprecipitation and whether these different EPS-mineral association pathways affect EPS sorption and selective retention, and thus the mobility and fate of microbially-derived OM in the soil environment. We use several complimentary techniques to i) examine EPS-carbon, EPS-nitrogen and EPS-phosphorus sorption and fractionation, ii) visualize spatial relationships between EPS biomolecular classes and ferrihydrite using confocal laser scanning microscopy (CLSM), iii) determine EPS-C speciation and chemical fractionation with ferrihydrite using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and iv) determine functional group interactions with ferrihydrite using Fourier transform infrared spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy (2D-COS) analysis. Results show that the coprecipitation of EPS does not change the ferrihydrite mineralogy, as the main mineral phase for EPS association, but it substantially increases the particle size of EPS-ferrihydrite. A substantial difference in the EPS mass fraction associated with the ferrihydrite is observed between the adsorption and coprecipitation experiments at an initial molar C/Fe ratio >1. The EPS-N is relatively enriched during the adsorption process, while more EPS-C and near-complete EPS-P are fixed in the coprecipitation process. XPS results show that the surface of the ferrihydrite formed through EPS adsorption is preferentially enriched with protein-like components, whereas, the surface of the ferrihydrite formed through EPS coprecipitation is enriched with polysaccharide-like components, which is visually confirmed with CLSM images. NEXAFS results reveal that the carboxylic/amide C-containing components are selectively retained during adsorption, with the aliphatic and O-alkyl C-containing components relatively enriched during coprecipitation. 2D-FTIR-COS results indicate that during EPS adsorption on ferrihydrite the Pdouble bondO functional groups are adsorbed faster than the amide and carboxylate functional groups, while during EPS coprecipitation with ferrihydrite the opposite trend is observed. The findings from this study indicate that the formation pathway of EPS-ferrihydrite associations substantially effects the sorption mechanisms and selective retention of EPS and may thus affect the mobility and fate of microbially-derived carbon (C), nitrogen (N) and phosphorus (P) in soils. These new insights on EPS behaviour at the mineral–water interface might be used to evaluate how microbially-derived compounds like EPS are stabilized by iron (oxyhydr)oxides and how EPS-iron (oxyhydr)oxide couplings might affect the reactivity and cycling of OM in natural environments

Estimation of cancer incidence and mortality attributable to alcohol drinking in china

Background. Cancer constitutes a serious burden of disease worldwide and has become the second leading cause of death in China. Alcohol consumption is causally associated with the increased risk of certain cancers. Due to the current lack of data and the imperative need to guide policymakers on issues of cancer prevention and control, we aim to estimate the role of alcohol on the cancer burden in China in 2005. Methods. We calculated the proportion of cancers attributable to alcohol use to estimate the burden of alcohol-related cancer. The population attributable fraction was calculated based on the assumption of no alcohol drinking. Data on alcohol drinking prevalence were from two large-scale national surveys of representative samples of the Chinese population. Data on relative risk were obtained from meta-analyses and large-scale studies. Results. We found that a total of 78,881 cancer deaths were attributable to alcohol drinking in China in 2005, representing 4.40% of all cancers (6.69% in men, 0.42% in women). The corresponding figure for cancer incidence was 93,596 cases (3.63% of all cancer cases). Liver cancer was the main alcohol-related cancer, contributing more than 60% of alcohol-related cancers. Conclusions. Particular attention needs to be paid to the harm of alcohol as well as its potential benefits when making public health recommendations on alcohol drinking. \ua9 2010 Liang et al; licensee BioMed Central Ltd

Prevalence and trend of hepatitis C virus infection among blood donors in Chinese mainland: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Blood transfusion is one of the most common transmission pathways of hepatitis C virus (HCV). This paper aims to provide a comprehensive and reliable tabulation of available data on the epidemiological characteristics and risk factors for HCV infection among blood donors in Chinese mainland, so as to help make prevention strategies and guide further research.</p> <p>Methods</p> <p>A systematic review was constructed based on the computerized literature database. Infection rates and 95% confidence intervals (95% CI) were calculated using the approximate normal distribution model. Odds ratios and 95% CI were calculated by fixed or random effects models. Data manipulation and statistical analyses were performed using STATA 10.0 and ArcGIS 9.3 was used for map construction.</p> <p>Results</p> <p>Two hundred and sixty-five studies met our inclusion criteria. The pooled prevalence of HCV infection among blood donors in Chinese mainland was 8.68% (95% CI: 8.01%-9.39%), and the epidemic was severer in North and Central China, especially in Henan and Hebei. While a significant lower rate was found in Yunnan. Notably, before 1998 the pooled prevalence of HCV infection was 12.87% (95%CI: 11.25%-14.56%) among blood donors, but decreased to 1.71% (95%CI: 1.43%-1.99%) after 1998. No significant difference was found in HCV infection rates between male and female blood donors, or among different blood type donors. The prevalence of HCV infection was found to increase with age. During 1994-1995, the prevalence rate reached the highest with a percentage of 15.78% (95%CI: 12.21%-19.75%), and showed a decreasing trend in the following years. A significant difference was found among groups with different blood donation types, Plasma donors had a relatively higher prevalence than whole blood donors of HCV infection (33.95% <it>vs </it>7.9%).</p> <p>Conclusions</p> <p>The prevalence of HCV infection has rapidly decreased since 1998 and kept a low level in recent years, but some provinces showed relatively higher prevalence than the general population. It is urgent to make efficient measures to prevent HCV secondary transmission and control chronic progress, and the key to reduce the HCV incidence among blood donors is to encourage true voluntary blood donors, strictly implement blood donation law, and avoid cross-infection.</p

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Efficacy of pemetrexed plus platinum doublet chemotherapy as first-line treatment for advanced nonsquamous non-small-cell-lung cancer: a systematic review and meta-analysis

Huai-Qing Xiao,1 Rong-Hua Tian,2 Zhi-Hao Zhang,1 Kai-Qi Du,1 Yi-Ming Ni3 1Department of Cardiothoracic Surgery, Zhejiang Corps Hospital, Chinese People&rsquo;s Armed Police Force, Jiaxing, Zhejiang Province, People&rsquo;s Republic of China; 2Department of Respiratory, Affiliated Haian People&rsquo;s Hospital of Nantong University, Haian, Jiangsu, People&rsquo;s Republic of China; 3Department of Cardiothoracic Surgery, The First Affiliated Hospital of Zhejiang University, Hangzhou, Zhejiang Province, People&rsquo;s Republic&nbsp;of China Purpose: To assess the efficacy of pemetrexed plus platinum doublet chemotherapy as first-line treatment for advanced nonsquamous non-small-cell lung cancer (NSCLC) through a trial-level meta-analysis. Methods: Trials published between 1990 and 2015 were identified by an electronic search of public databases (Medline, Embase, and Cochrane Library). All clinical studies were independently identified by two authors. Demographic data, treatment regimens, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were extracted and analyzed using comprehensive meta-analysis software (version 2.0). Results: A total of 2,551 patients with advanced nonsquamous NSCLC from ten trials were included for analysis: 1,565 patients were treated with pemetrexed plus platinum doublet chemotherapy and 986 with platinum plus other first-line chemotherapy. Pooled ORR for pemetrexed plus platinum chemotherapy was 37.8% (95% confidence interval [CI]: 31.7%&ndash;44.3%), with median PFS and OS of 5.7 and 16.05 months, respectively. When compared to other platinum-based doublet chemotherapies, the use of pemetrexed plus platinum chemotherapy significantly improved OS (hazard ratio [HR] =0.86, 95% CI: 0.77&ndash;0.97, P=0.01) but not PFS (HR =0.90, 95% CI: 0.80&ndash;1.01, P=0.084) in advanced nonsquamous NSCLC patients. Conclusion: Pemetrexed plus platinum doublet regimen is an efficacious treatment for advanced nonsquamous NSCLC patients. Our findings support the use of pemetrexed plus platinum doublet regimen as first-line treatment in advanced nonsquamous NSCLC patients because of its potential survival benefits. Keywords: chemotherapy-naive, lung cancer, pemetrexed, pooled analysis, randomized controlled trial

The mobility and fate of Cr during aging of ferrihydrite and ferrihydrite organominerals

The fixation of environmentally hazardous Cr(VI) in soils is largely attributed to its retention by iron (Fe) (oxyhydr)oxides in the soil environment, which are prevailingly associated with organic carbon (OC). The effect of OC with different binding strengths on Cr(VI) adsorption and the mobility and fate of Cr(VI) during aging of Fe (oxyhydr)oxide however, are unknown. Here we investigate how OC binding strength influences Cr(VI) adsorption to ferrihydrite (Fh) organominerals, the aging of Fh organominerals and the subsequent retention or release of Cr(VI) as aging proceeds. We conduct Cr(VI) adsorption experiments onto Fh organominerals, apply surface complexation modelling to study the relative binding strengths between OC and Cr(VI), and then conduct aging experiments to track the redistribution of Cr(VI). We show based on the relative binding strength between OC and Cr(VI), that weakly-bound OC at different C loadings has almost no discernable influence on Cr(VI) adsorption, while strongly-bound OC significantly suppresses Cr(VI) adsorption via surface site blocking and/or electrostatic repulsion. The mobility and fate of Cr(VI) with Fh organominerals during the aging process is strongly influenced by the presence of OC. Weakly-bound carboxyl-poor OC not only near doubles the rate of Cr(VI) retained (i.e., Cr(VI) redistribution from a weakly-bound to a strongly-bound fraction) in neoformed Fe minerals at pH 5.0, but also increases the final proportion of Cr(VI)strongly-bound, which we attribute to the loose and porous structure of Fh organominerals and easier replacement of weakly-bound OC by Cr(VI). More strongly-bound carboxyl-rich OC and higher pH however, reduces the influence of OC, such that the rate of Cr(VI) retained is similar to or lower than that for the pure Fh system, which we attribute to the fact that the strongly-bound OC is less easily replaced by Cr(VI) and hence Cr(VI) is less able to access surface sites or surface pores and thus to be retained inside neoformed minerals. Overall we suggest that OC with higher carboxyl-richness will further suppress the rate of Cr(VI) retained and overall proportion of Cr(VI)strongly-bound, and thus that the mobility and fate of Cr(VI) in soils is strongly controlled by the carboxyl-richness of OC in Fe organominerals