Discrimination of single-stranded DNA homopolymers by sieving out G-quadruplex using tiny solid-state nanopores.

Nanopore sensor has been developed as a promising technology for DNA sequencing at the single-base resolution. However, the discrimination of homopolymers composed of guanines from other nucleotides has not been clearly revealed due to the easily formed G-quadruplex in aqueous buffers. In this work, we report that a tiny silicon nitride nanopore was used to sieve out G tetramers to make sure only homopolymers composed of guanines could translocate through the nanopore, then the 20-nucleotide long ssDNA homopolymers could be identified and differentiated. It is found that the size of the nucleotide plays a major role in affecting the current blockade as well as the dwell time while DNA is translocating through the nanopore. By the comparison of translocation behavior of ssDNA homopolymers composed of nucleotides with different volumes, it is found that smaller nucleotides can lead to higher translocation speed and lower current blockage, which is also found and validated for the 105-nucleotide long homopolymers. The studies performed in this work will improve our understanding of nanopore-based DNA sequencing at single-base level.

Promotion of levoglucosan production from biomass pyrolysis by hydrogen peroxide pre-oxidation.

Due to the complexity of biomass structures, the conversion of raw biomass into value-added chemicals is challenging and often requires efficient pretreatment of the biomass. In this paper, a simple and green pre-oxidation method, which was conducted under the conditions of 2 wt% H2O2, 80 min, and 150 °C, was reported to significantly increase the production of levoglucosan (LG) from biomass pyrolysis. The result showed that the LG yield significantly increased from 2.3 wt% (without pre-oxidation) to 23.1 wt% when pine wood was employed as a sample for pyrolysis at 400 °C, resulting from the removal of hemicellulose fraction and the in-situ acid catalysis of lignin carboxyl groups formed during the pre-oxidation. When the conditions for pre-oxidation became harsher than the above, the LG yield reduced because the decomposition of cellulose fraction in biomass. The study supplies an effective method for utilization of biomass as chemicals.

Comparison of peginterferon and interferon in treating Chinese patients with chronic hepatitis C.

BACKGROUND/AIMS: Higher virological and biochemical response rates were obtained in many clinical trials in Caucasian patients with chronic hepatitis C (CHC) after treating with peginterferon than in those with interferon. However, it is not clear whether this conclusion can be extrapolated to patients with Chinese ethnic origin and which type of peginterferon or interferon was more effective in treating Chinese CHC patients? The aim of this study was to perform a meta-analysis of randomized controlled trials (RCT) and compare peginterferon with interferon in treating Chinese patients with CHC. METHODOLOGY: The outcome measures were virological response (end-of-treatment virological response (ETVR) and sustained virological response (SVR)). Biochemical response (end-of-treatment biochemical response (ETBR) and sustained biochemical response (SBR) were also introduced as supplement to the evaluation on effect of peginterferon and interferon in treating Chinese patients with CHC. The measure of association employed was relative risk (RR) calculated by the random-effect model, with heterogeneity, sensitivity and subgroup analyses. RESULTS: Of the 110 studies screened, 5 RCTs including 499 patients (peginterferon 258, interferon 241) were analyzed. SVR and SBR obtained in patients treated with peginterferon were significantly higher than patients treated with interferon (60% vs. 35.53%, RR, 1.95; 95% confidence interval (CI), 1.17-3.24; p<0.05; 57.30% vs. 40.38%, RR, 1.36; 95% CI, 1.08-1.71; p<0.05), but the difference is not evident in ETVR and ETBR. In the subgroup analyses, ETVR and SVR obtained in patients treated with peginterferon alpha-2a (79.75% and 48.1%) were significantly higher than with interferon alpha-2a (35.37% vs. 19.05%, RR, 2.51; 95% CI, 1.74-3.63; p<0.05), but the difference is not evident between peginterferon alpha-2b and interferon alpha-2b. SBR obtained with peginterferon was also significantly higher than with interferon (57.3% vs. 40.38%, RR, 1.36; 95% CI, 1.08-1.71; p<0.05), but the difference is not evident in EBVR. Higher SVR were obtained in genotype 1 Chinese patients treated with peginterferon compared with those treated with interferon (48.45% vs. 23.24%, RR, 2.00; 95% CI, 1.48-2.7; p<0.01), but the ETVR were similar. The effects of peginterferon and interferon in genotype non-1 patients were also similar. Higher ETVR and SVR were obtained in patients treated with peginterferon alpha-2b compared with those treated with peginterferon alpha-2a (97.56% vs. 79.75% and 82.93% vs. 56.96%; p<0.05 and p<0.01, respectively). SVR obtained in patients treated with peginterferon alpha-2b were significantly higher than those treated with peginterferon alpha-2a (73.53% vs. 41.73%, p<0.01) in treating genotype 1 Chinese patients, but the superiority didn't appear in treating genotype non-1 patients. CONCLUSIONS: Both peginterferon alpha-2a and peginterferon alpha-2b might be recommended for Chinese ethnic original patients with CHC. Peginterferon alpha-2b might be more effective, with an expected relative higher virological response and biochemical response, in treating Chinese CHC patients.

Analysis of interleukin-8 gene variants reveals their relative importance as genetic susceptibility factors for chronic periodontitis in the Han population.

Interleukin (IL)-8, an important chemokine that regulates the inflammatory response, plays an important role in periodontitis. Previous studies indicate that certain IL-8 gene polymorphisms are associated with periodontitis susceptibility in some populations. However, the literature is somewhat contradictory, and not all IL-8 polymorphisms have been examined, particularly in Han Chinese individuals. The aim of this study was to investigate the association of every IL-8 SNP with chronic periodontitis in Han Chinese individuals. We analyzed 23 SNPs with minor allele frequency (MAF)≥0.01, which were selected from 219 SNPs in the NCBI dbSNP and preliminary HapMap data analyses from a cohort of 400 cases and 750 controls from genetically independent Han Chinese individuals. Single SNP, haplotype and gender-specific associations were performed. We found that rs4073 and rs2227307 were significantly associated with chronic periodontitis. Further haplotype analysis indicated that a haplotype block (rs4073-rs2227307-rs2227306) that spans the promoter and exon1 of IL-8 was highly associated with chronic periodontitis. Additionally, the ATC haplotype in this block was increased 1.5-fold in these cases. However, when analyzing the samples by gender, no significant gender-specific associations in IL-8 were observed, similar to the results of haplotype association analyses in female and male subgroups. Our results provide further evidence that IL-8 is associated with chronic periodontitis in Han Chinese individuals. Furthermore, our results confirm previous reports suggesting the intriguing possibilities that IL-8 plays a role in the pathogenesis of chronic periodontitis and that this gene may be involved in the etiology of this condition.