An on-chip pollutant toxicity determination based on marine microalgal swimming inhibition.

We report the use of microalgal swimming behavior as a sensor signal integrated into microfluidics for a rapid and high-throughput determination of pollutant toxicity. There are two types of chip. A poly(dimethylsiloxane) (PDMS) 12-well chip, used for optimization of experimental conditions (i.e. light level, temperature, initial cellular density and exposure time), can perform twelve parallel tests simultaneously. In a concentration gradient generator (CGG) chip, a CGG connected with diffusible chambers enables a large number of dose-response bioassays to be performed in a simple way. Microalgal swimming was set as a microfluidic bioassay signal and was evaluated as swimming manner, motile percentage (%MOT), curvilinear velocity (VCL), average path velocity (VAP) and straight line velocity (VSL). Under optimized physical conditions, the toxicities of Cu, Pb, phenol and nonylphenol (NP) towards four mobile marine microalgae, Platymonas subcordiformis, Platymonas helgolandica var. tsingtaoensis, Isochrysis galbana and Isochrysis zhanjiangensis sp. nov, were investigated. In all cases, a toxic response (i.e. a dose-related inhibition of swimming) was detected, and a time of only 2 h was needed to predict EC50 values. The 2h-EC50s showed that I. galbana was the most tolerant and that P. subcordiformis was one of the most sensitive. Based on the relative motile percentage data, the EC50 values for Cu of I. galbana and P. subcordiformis were 6.04 and 1.67 µM, respectively, while for Pb the EC50 values were 15.30 and 3.87 µM, for phenol the EC50 values were 8.69 and 6.08 mM, and for NP the EC50 values were 29.65 and 14.47 µM, respectively. Taking into account all the swimming inhibition parameters, MOT provided more sensitive EC results. The sensitivity differences between the velocity parameters (VCL, VAP and VSL) were ascribed to differences in swimming manner of the different classes of microalgae.

Water-bath assisted convective assembly of aligned silver nanowire films for transparent electrodes.

Manipulating Ag nanowire (AgNW) assembly to tailor the opto-electrical properties and surface morphology could improve the performance of next-generation transparent conductive electrodes. In this paper, we demonstrated a water-bath assisted convective assembly process at the temporary water/alcohol interface for fabricating hierarchical aligned AgNW electrodes. The convection flow plays an important role during the assembly process. The assembled AgNW film fabricated via three times orthogonal dip-coating at a water-bath temperature of 80 °C has a sheet resistance of 11.4 Ω sq(-1) with 89.9% transmittance at 550 nm. Moreover, the root mean square (RMS) of this assembled AgNW film was only 15.6 nm which is much lower than the spin-coated random AgNW film (37.6 nm) with a similar sheet resistance. This facile assembly route provides a new way for manufacturing and tailoring ordered nanowire-based devices.

Paper-based three-dimensional microfluidic device for monitoring of heavy metals with a camera cell phone.

A 3D paper-based microfluidic device has been developed for colorimetric determination of selected heavy metals in water samples by stacking layers of wax patterned paper and double-sided adhesive tape. It has the capability of wicking fluids and distributing microliter volumes of samples from single inlet into affrays of detection zones without external pumps, thus a range of metal assays can be simply and inexpensively performed. We demonstrate a prototype of four sample inlets for up to four heavy metal assays each, with detection limits as follows: Cu (II) = 0.29 ppm, Ni(II) = 0.33 ppm, Cd (II) = 0.19 ppm, and Cr (VI) = 0.35 ppm, which provided quantitative data that were in agreement with values gained from atomic absorption. It has the ability to identify these four metals in mixtures and is immune to interferences from either nontoxic metal ions such as Na(I) and K(I) or components found in reservoir or beach water. With the incorporation of a portable detector, a camera mobile phone, this 3D paper-based microfluidic device should be useful as a simple, rapid, and on-site screening approach of heavy metals in aquatic environments.

An integrated microfludic device for culturing and screening of Giardia lamblia.

In vitro culturing of trophozoites was important for research of Giardia lamblia (G. lamblia), especially in discovery of anti-Giardia agents. The current culture methods mainly suffer from lab-intension or the obstacle in standardizing the gas condition. Thus, it could benefit from a more streamlined and integrated approach. Microfluidics offers a way to accomplish this goal. Here we presented an integrated microfluidic device for culturing and screening of G. lamblia. The device consisted of a polydimethylsiloxane (PDMS) microchip with an aerobic culture system. In the microchip, the functionality of integrated concentration gradient generator (CGG) with micro-scale cell culture enables dose-response experiment to be performed in a simple and reagent-saving way. The diffusion-based culture chambers allowed growing G. lamblia at the in vivo like environment. It notable that the highly air permeable material of parallel chambers maintain uniform anaerobic environment in different chambers easily. Using this device, G. lamblia were successfully cultured and stressed on-chip. In all cases, a dose-related inhibitory response was detected. The application of this device for these purposes represents the first step in developing a completely integrated microfluidic platform for high-throughput screening and might be expanded to other assays based on in vitro culture of G. lamblia with further tests.

[Efficacy of standard antiviral therapy retreatment following interferon treatment failure in chronic hepatitis C patients].

OBJECTIVE: To investigate the therapeutic efficacy of standard antiviral therapy applied after interferon (IFN) treatment failure in patients with chronic hepatitis C (CHC). METHODS: CHC patients who completed a 48-week course of IFN therapy (pegylated (Peg)-IFNa-2a at 180 mug, qw, ih with or without ribavirin (RBV) at 15 mg/kg/w) in our hospital between January 2009 and June 2012 but who showed no response (at week 48) or who relapsed (at week 72) were enrolled in the study. Prior to initiating the 48-week course of retreatment therapy (Peg-IFNa-2a plus RBV as above), the hepatitis C virus (HCV) genotype was detected and the viral load measured (baseline) by PCR of HCV RNA. Each patient's response to therapy was classified as follows: baseline vs. week 4 (rapid virological response, RVR), vs. weeks 12 and 24 (early virological response, EVR), vs. week 48 (end of treatment virological response, ETVR) and vs. week 72 (sustained virological response, SVR). RESULTS: Of the total 235 cases administered retreatment therapy, 60.0% (n = 140) achieved RVR, 77.4% (n = 182) achieved EVR, 83.8% (n = 197) achieved ETVR, 68.0% (n = 68%) achieved SVR, and 15.7% (n = 37) relapsed. Stratification analysis of recurrence (n = 158) and non-responsive (n = 77) sub-groups showed that the recurrence group experienced significantly higher rates of RVR, EVR, ETVR and SVR, but a significantly lower rate of relapse. Stratification analysis of genotype 1b carrier (n = 206) and non-1b carrier (n = 29) sub-groups showed that the 1b carriers had significantly lower rates of RVR, EVR, ETVR and SVR, but a significantly higher rate of relapse. Finally, the patients who achieved RVR (vs. non RVR, n = 95) and EVR (vs. non-EVR, n = 53) showed higher rates of SVR and ETVR. CONCLUSION: CHC patients who fail to respond to the initial course of standard IFN-based therapy may achieve SVR upon retreatment, especially those infected with the HCV genotype 1b.

Update analysis of studies on the MMP-9 -1562 C>T polymorphism and cancer risk.

Polymorphisms in the matrix metalloproteinase (MMP) gene have been hypothesized to be functional and may contribute to genetic susceptibility to cancers. The common sequence variation in MMP-9 -1562 C>T (rs3918242), has been involved in cancer risk. However, results of the related published studies were somewhat controversial and underpowered in general. To clarify the role of MMP-9 -1562 C>T genotype in global cancer, we performed a meta-analysis of all the available published studies involving 4,124 cancer patients and 4,728 control subjects. The overall results indicated that there was no major association of the variant on cancer risk. However, stratified analysis by cancer type showed that the MMP-9 -1562 C>T polymorphism has a lower risk in colorectal cancer (OR = 0.80, 95%CI = 0.66-0.96, P (heterogeneity) = 0.391) and lung cancer (OR = 0.70, 95%CI = 0.51-0.96, P (heterogeneity) = 0.959) by allelic contrast. Furthermore, association of the MMP-9 -1562 C>T polymorphism and cancer risk was also observed in hospital-based studies under the dominant genetic model (OR = 0.87, 95%CI = 0.78-0.97, P (heterogeneity) = 0.355), allelic contrast (OR = 0.85, 95%CI = 0.75-0.96, P (heterogeneity) = 0.271) and heterozygote comparison (OR = 0.89, 95%CI = 0.79-0.99, P (heterogeneity) = 0.402). This pooled analysis showed evidence that the MMP-9 -1562 C>T polymorphism may decrease both the colorectal and lung cancer risk. Further prospective studies with larger numbers of participants worldwide are required to evaluate the association in more detail.

[Expression of Notch1 in the genital tubercle of male rats with hypospadias induced by Di-n-butyl phthalate].

OBJECTIVE: To detect the differential expression of Notch1 in the genital tubercle (GT) of fetal male rats with hypospadias induced by maternal exposure to Di-n-butyl phthalate (DBP) and that in normal control fetal rats in order to further explore the role of Notch1 in DBP-induced hypospadias. METHODS: Twenty pregnant SD rats were equally and randomly divided into an experimental and a control group, the former given DBP and the latter soybean oil intragastrically at 800 mg/(kg x d) and 2 ml/d respectively from gestation day (GD) 14 to GD 18. On GD 19, the birth weight (BW), anogenital distance (AGD) and hypospadias incidence were recorded, GTs of the fetal male rats collected, and the expression of Notch1 analyzed by Western blot and immunohistochemistry. RESULTS: The BW of the fetal male rats was (4.40 +/- 0.30) g in the experimental group, significantly lower than (6.11 +/- 0.40) g in the control (P <0.05), and the AGD was (2.17 +/- 0.18) mm in the former, markedly shorter than (3.28 +/- 0.16) mm in the latter (P<0.05). The incidence of hypospadias was 42.9%. The relative expression of Notch1 was remarkably lower in the hypospadiac rats than in the normal controls (0.671 +/- 0.021 vs 1.327 +/- 0.031, P<0.05), and it was mainly located in the epithelial cells of the GT. The staining intensity was obviously weaker in the hypospadias than in the normal control group. CONCLUSION: DBP has an obvious toxic effect on fetal male rats and can change the expression of Notch1 in the GT. It possibly affects cell proliferation and apoptosis and epithelial-to-mesenchymal transition (EMT), resulting in the occurrence of hypospadias.

RNASEL -1385G/A polymorphism and cancer risk: a meta-analysis based on 21 case-control studies.

Polymorphisms in the endoribonuclease L (RNASEL) gene have been hypothesized to increase the incidence of cancer. The common sequence variation in RNASEL, -1385G/A (rs486907) has been involved in several types of cancer risk. However, results of the related published studies remained conflicting rather than conclusive. To clarify the role of RNASEL -1385G/A genotype in global cancer, we performed a meta-analysis of all the available published studies involving 8,732 cancer patients and 8,748 control subjects. The overall results indicated that there was no major influence of the variant on cancer risk. However, stratified analysis by ethnicity showed that the RNASEL -1385G/A polymorphism has an increased cancer risk in African descendents in the homozygote comparison (OR = 2.59, 95% CI = 1.27-5.27), although no association was found in the analysis stratified by cancer type (OR = 1.12, 95% CI = 0.94-1.35). This meta-analysis suggested that the RNASEL -1385G/A polymorphism is associated with cancer risk in African descendents. To draw more comprehensive conclusions, further prospective studies with larger numbers of participants worldwide are still required to examine associations between RNASEL -1385G/A polymorphism and cancer risk.

[Identification the relationship between mutation patterns of rtM204I/V in the polymerase gene and genotypes of hepatitis B virus].

OBJECTIVE: To investigate the relationship between the mutation patterns of rtM204V/I (methionine to valine or isoleucine at position rt204 of reverse transcriptase domain) in hepatitis B virus (HBV) polymerase gene and HBV genotypes. METHODS: A total of 2849 HBV complete genome sequences were retrieved from the GenBank/EMBL/DDBJ. HBV genotypes were determined by using MEGA4 software. The amino acid sequences of the reverse transcriptase (RT) domain were aligned. Data were analyzed using SPSS 13.0. RESULTS Among the 2849 HBV complete genome sequences, 217 strains with Y (I/V) DD were identified. Of them, 120 had YIDD mutation and the genotype/subgenotype distribution was as follows: A (2), B(B2 19), C(C1 1, C2 78, C5 1), D(17), E(1), G(1); 97 had YVDD mutation and the genotype/subgenotype distribution was as follows: A(17), B(B2 22), C(C1 3, C2 48), D(3), G(3), H(1). There is a significant difference in the mutation patterns of Y (I/V) DD among genotypes of A-D, A-C, and between genotype A and B, P < 0.01.There is a difference in the mutation pattern of Y (I/V) DD among genotypes of B-D, between genotype C and D, P < 0.05. Genotype A has a higher tendency to develop YVDD mutation, whereas genotype D has a higher frequency to develop YIDD mutation. The rtM204V-rtL180M mutations were more frequently found in subgenotype B2 than in subgenotype C2 while the rtM204V-rtL180M-rtV173L mutations were more associated with subgenotype C2 (P < 0.01). CONCLUSION: Different HBV genotype/subgenotype may select different mutation pattern in the YMDD domain. Subgenotype C2 is more diversity and complexity than other HBV genotypes/subgenotypes.

[Application of microfluidics in aquatic environmental pollution analysis].

Recently, a new type of chip technology, microfluidics, has received global attention for its rapid analysis speed, low reagent consumption, small size and simple operation, etc. Based on a micro-channel network and supported by a Micro-Electro-Mechanic System (MEMS), this technology integrates all the functions of a laboratory into one small piece of chip, which is called "lab on the chip". This paper presented a brief introduction about microfluidics and its representative developments. Future prospects in the aspects of instrument miniaturization, system integration, chip materials, and detection techniques, as well as the implementation of microfluidics in aquatic environmental pollutant analysis were thoroughly discussed. Some problems faced now were put forward. With the rapid progress in the microfluidics, a universal low-cost microchip capable of high speed multi-channel detection and integrated with many kinds of detection methods would be the research focus in the future.

[Phosphorus forms of the suspended particulate matter in the Yellow River downstream during water and sediment regulation 2008].

Suspended particulate matter samples were collected from Lijin Station on the Yellow River during the 2008 water and sediment regulation. Using water elutriation method, samples were physically separated according to grain size, and phosphorus forms were detected by the improved SEDEX technology. Results show that authigenic apatite phosphorus and organic phosphorus are the dominant forms of the particulate phosphorus. During water and sediment regulation, concentrations of total particulate phosphorus, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus are lower than those in other time of the year, while the concentration of detrital fluorapatite phosphorus is higher than that in other time. Grain size is the primary variable in the determination of the content of various particulate phosphorus forms. In fine particles, loosely adsorbed phosphorus, organic phosphorus and refractory phosphorus concentrations are high, while detrital fluorapatite phosphorus concentration is high in coarse particles. About 28.3% of the total particulate phosphorus is in the form of bio-available phosphorus, of which organic phosphorus is the major component. During the water and sediment regulation, the fluxes of sediment, particulate phosphorus and particulate bio-available phosphorus are 6.63 x 10(7) t, 3.42 x 10(4) t, and 8.30 x 10(3) t, which are 83.2%, 78.6%, and 80.2% each of the total fluxes in 2008.

[Effects of climate factors on the epidemic of apple Marssonina blotch in Shaanxi Province and related prediction models].

Based on the long term (1999-2008) monitoring of air temperature and relative humidity and of the occurrence and epidemiological trend of Marssonina blotch in the main apple-production area of Shaanxi Province, this paper analyzed the occurrence time, pathogenesis regularity, and epidemiological level of Marssonina blotch, with the 1- and 3-dimensional models for predicting Marssonina blotch under effects of ten-day mean air temperature (T) and relative humidity (Hm) constructed. In study area, the development of Marssonina blotch was mainly affected by environment factors. This disease spread rapidly in field in July and August, causing orchard defoliation, and the harm persisted until September. After the first frost, new disease spots no longer developed. The data of T and Hm in the models showed a good fitting with field condition. The 3-dimensional dynamic prediction model of Marssonina blotch was f(T, Hm) = -0.0172 T3 + 0.9497T2--16.2209T + 88.9923-0.00001Hm3 + 0.00354Hm2--0.15554Hm + 2.36578, where f(T, Hm) was disease index. The modeling results showed that the T for the occurrence of Marssonina blotch in field was 15 degrees C, and the disease would have an epidemic peak when the T and Hm in July and August reached 23 degrees C and > or = 90%, respectively.

[A novel method for hepatitis C virus genotyping using RT-PCR reverse dot blot hybridization technique].

OBJECTIVE: To develop a rapid and specific method for hepatitis C virus ( HCV) genotyping using reverse dot blot hybridization technique and investigate the distribution of HCV genotypes and subtypes in Guangdong. METHODS: The primers and the probes targeting the 5'untranslated region (5'UTR) and core region of HCV genotypes 1b, 2a, 3a, 3b and 6a were designed, and the RT-PCR reverse dot blot hybridization (PCR-RDH) method for HCV genotyping was established. A total of 115 patients with hepatitis C were genotyped using this method, and 38 of them were also genotyped by sequencing and phylogenetic analysis to evaluate the accuracy and specificity of the method. RESULTS: Of the 115 patients, 111 were successfully genotyped to be 1b, 2a, 3a, 3b, 6a and mix-infection of 1b/2a at frequencies of 56.8%, 8.1 %, 3.6%, 5.4%, 25.2% and 0.9% respectively, and all the 15 healthy control samples showed negative results. The accuracy and reliability of the genotyping method of PCR-RDH was confirmed in 38 cases by amplification of HCV core and NS5B regions followed by DNA sequencing and phylogenetic analysis. CONCLUSION: This method for HCV genotyping, with high reliability and specificity, is suitable for clinical and epidemiological investigations. The prevalence of HCV genotypes 1b and 2a decreases while 1b remains the dominant genotype in Guangdong, where the prevalence of 6a significantly increases as compared with that 10 years ago.

[Preparation of human anti-HBs from volunteers with hepatitis B vaccine boost vaccination by modified B-cell immortalization technique].

OBJECTIVE: To establish immortalized B lymphoblast cell lines (B-LCLs) from healthy anti-HBs antibody (anti-HBs)-positive volunteers and screen for human anti-HBs and the antibody-secreting cells. METHODS: The peripheral blood mononuclear cells (PBMC) isolated from 3 healthy volunteers positive for anti-HBs with hepatitis B vaccine boost vaccination were infected with Epstein-Barr virus (EBV) and incubated in the presence of CpG DNA motifs and cyclosporin A (CyA). The anti-HBs in the culture supernatant of the immortalized B-cells was quantified by Architect anti-HBs assay with chemiluminescent microparticle technique. Immunocytochemistry was performed to identify the differentiation of the cell clones expressing anti-HBs. RESULTS: Immortalized B-cell culture was successfully established from the cell clones secreting anti-HBs with EBV infection and CpG DNA stimulation. The titer of anti-HBs in the culture supernatant was at its peak at 3 weeks of cell culture and then decreased gradually. At 3 months of cell culture, the cells still retained the capacity of anti-HBs production as verified by the results of immunocytochemistry for CD20 and CD138. CONCLUSION: Immortalized B-cell culture secreting anti-HBs from volunteers receiving boost hepatitis B vaccination has been successfully established by modified EBV immortalization technique.