Controllable transition of silk fibroin nanostructures: an insight into in vitro silk self-assembly process

Silk fiber is one of the strongest and toughest biological materials with hierarchical structures, where nanofibril with size <20nm is a critical factor in determining its excellent mechanical properties. Although silk nanofibrils have been found in natural and regenerated silk solutions, there is no way to actively control nanofibril formation in aqueous solution. This study shows a simple but effective method of preparing silk nanofibrils by regulating the silk self-assembly process. Through a repeated drying-dissolving process, a silk fibroin solution composed of metastable nanoparticles was first prepared and then used to reassemble nanofibrils with different sizes and secondary conformations under various temperatures and concentrations. These nanofibrils have a similar size to that of natural fibers, providing a suitable unit to further assemble the hierarchical structure in vitro. Several important issues, such as the relationships between silk nanofibrils, secondary conformations and viscosity, are also investigated, giving a new insight into the self-assembly process. In summary, besides rebuilding silk nanofibrils in aqueous solution, this study provides an important model for furthering the understanding of silk structures, properties and forming mechanisms, making it possible to regenerate silk materials with exceptional properties in the future.

Influence of different urination methods on the urinary systems of patients with spinal cord injury

OBJECTIVE

This study evaluated the influence of different urination methods on the urinary systems of patients with spinal cord injury.

METHODS

Patients with spinal cord injury were grouped according to their usual voiding method: clean intermittent catheterization (CIC); Credé manoeuvre/reflex voiding; indwelling catheterization; normal voiding. Urinary tract infections (UTIs) were monitored and type B-ultra-sonography (B-USG) scans, renal function tests and urodynamic studies were performed in all patients over a 2-year period.

RESULTS

Compared with the normal voiding group (n = 14), incidence rates of UTIs were significantly different in the Credé manoeuvre/reflex voiding (n = 26) and indwelling catheterization (n = 12) groups but not in the CIC group (n = 15). All intervention groups had a significantly higher rate of positive findings on B-USG scan and a significantly increased residual urine volume, compared with the normal voiding group. In addition, residual urine volume was significantly lower in the CIC group compared with the Credé manoeuvre/reflex voiding and indwelling catheterization groups.

CONCLUSION

CIC was shown to be the optimal method for assisted bladder voiding after spinal cord injury.

Medium modification of jet fragmentation in Au+Au collisions at √[s(NN)]=200 GeV measured in direct photon-hadron correlations

The jet fragmentation function is measured with direct photon-hadron correlations in p+p and Au+Au collisions at √[s(NN)]=200 GeV. The p(T) of the photon is an excellent approximation to the initial p(T) of the jet and the ratio z(T)=p(T)(h)/p(T)(γ) is used as a proxy for the jet fragmentation function. A statistical subtraction is used to extract the direct photon-hadron yields in Au+Au collisions while a photon isolation cut is applied in p+p. I(AA), the ratio of hadron yield opposite the photon in Au+Au to that in p+p, indicates modification of the jet fragmentation function. Suppression, most likely due to energy loss in the medium, is seen at high z(T). The associated hadron yield at low z(T) is enhanced at large angles. Such a trend is expected from redistribution of the lost energy into increased production of low-momentum particles.

Association of CYP2C9*2 with bosentan-induced liver injury

Bosentan (Tracleer) is an endothelin receptor antagonist prescribed for the treatment of pulmonary arterial hypertension (PAH). Its use is limited by drug-induced liver injury (DILI). To identify genetic markers of DILI, association analyses were performed on 56 Caucasian PAH patients receiving bosentan. Twelve functional polymorphisms in five genes (ABCB11, ABCC2, CYP2C9, SLCO1B1, and SLCO1B3) implicated in bosentan pharmacokinetics were tested for associations with alanine aminotransferase (ALT), aspartate aminotransferase (AST), and DILI. After adjusting for body mass index, CYP2C9*2 was the only polymorphism associated with ALT, AST, and DILI (β = 2.16, P = 0.024; β = 1.92, P = 0.016; odds ratio 95% CI = 2.29-∞, P = 0.003, respectively). Bosentan metabolism by CYP2C9*2 in vitro was significantly reduced compared with CYP2C9*1 and was comparable to that by CYP2C9*3. These results suggest that CYP2C9*2 is a potential genetic marker for prediction of bosentan-induced liver injury and warrants investigation for the optimization of bosentan treatment.

Effective process to achieve enhanced electrochromic performances based on poly(4,4',4″-tris[4-(2-bithienyl)pheny]amine)/ZnO nanorod composites

Poly(4,4',4″-tris[4-(2-bithienyl)pheny]amine) (PTBTPA) was electrochemically synthesized on a ZnO-coated ITO electrode to form a PTBTPA/ZnO nanocomposite electrode. The composite film exhibited a noticeable electrochromism, with reversible color changes from orange in the reduced state (0 V), olive green in the middle state (0.9 V) to dark gray in the oxidized state (1.2 V). Furthermore, the composite film showed a fast switching time of 0.92 s and a high optical contrast of 65% at 1100 nm, and retained 97% of its original electroactivity after 500 cycles, while PTBTPA film had switching time of 1.63 s and an optical contrast of 52% at 1100 nm, and retained 75% of its original electroactivity. The results demonstrated that the electrochromic performances were significantly enhanced through incorporating PTBTPA with ZnO nanorods. ZnO nanorods were introduced to modify the structure of the electrode: on one hand, to offer a directional attraction for the counterions, and on the other hand, to enhance the adhesion between the polymer and the ITO electrode. Accordingly, a conducting polymer/inorganic nanocomposite system could improve the polymer's electrochromic performance, especially in terms of the switching speed and long-term stability of the electrochromic materials.

The human MTHFR rs4846049 polymorphism increases coronary heart disease risk through modifying miRNA binding

BACKGROUND AND AIMS

Abnormal functioning of 5,10-methylenetetrahydrofolate reductase (MTHFR) enhances the risk for coronary heart disease (CHD). Here, we tested whether a single-nucleotide polymorphism (SNP) located in the 3' untranslated region (UTR) of MTHFR was associated with CHD susceptibility by affecting microRNAs binding.

METHODS AND RESULTS

We first analyzed in silico the SNPs localized in the 3' UTR of MTHFR for their ability to modify miRNA binding. We observed that rs4846049 (G > T) was a potential candidate SNP to modulate miRNAs:MTHFR mRNA complex, with the greatest changed binding free energy for has-miR-149. Based on luciferase analysis, hsa-miR-149 inhibited the activity of the reporter vector carrying -T allele, but not -G allele. We further conducted a case-control study (654 vs 455) in a Chinese Han population. rs4846049 was significantly associated with increased risk for CHD. In addition, the T allele was associated with decreased levels of HDL-cholesterol and apoA. Finally, we observed a reduced MTHFR protein level in peripheral blood mononuclear cells of CHD patients with TT carriers compared to GG carriers of rs4846049.

CONCLUSION

Our results suggest that rs4846049 (G > T) of MTHFR is associated with increased risk for CHD. We also identified a potentially pathogenetic mechanism of SNP-modified posttranscriptional gene regulation by miRNAs to MTHFR.

Observation of a charged charmoniumlike structure in e+ e- → π+ π- J/ψ at sqrt[s] = 4.26 GeV

We study the process ee+ e- → π+ π- J/ψ at a center-of-mass energy of 4.260 GeV using a 525  pb(-1) data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9±1.9±3.7)  pb, consistent with the production of the Y(4260). We observe a structure at around 3.9  GeV/c2 in the π(±)J/ψ mass spectrum, which we refer to as the Z(c)(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the π(±)J/ψ invariant mass spectrum, neglecting interference, results in a mass of (3899.0±3.6±4.9)  MeV/c2 and a width of (46±10±20)  MeV. Its production ratio is measured to be R = (σ(e+ e- → π(±)Z(c)(3900)(∓) → π+ π- J/ψ)/σ(e+ e- → π+ π- J/ψ)) = (21.5±3.3±7.5)%. In all measurements the first errors are statistical and the second are systematic.

Associated factors for HIV and syphilis infection among men who have sex with men only and men who have sex with both men and women in cities of China

Summary

The aims of this paper were to find out the status of HIV and syphilis infection and to examine the sexual behaviours between men who have sex with men only (MSM/M) and men who have sex with both men and women (MSM/W), as well as to determine the correlates for HIV and syphilis infection among MSM/M and MSM/W, respectively. Among 1693 MSM who participated in the study, the proportions of MSM/M and MSM/W were 82.1% and 17.9%, respectively. The prevalences of HIV infection were 7.0% in MSM/M and 6.6% in MSM/W and the prevalences of syphilis infection were 11.9% and 13.2%, respectively. Among the MSM/M subset, the correlates both for HIV and syphilis infection included having more sexual partners, and being receptive or both insertive and receptive for anal sex. Among the MSM/W subset, living in Chengdu was associated with HIV infection and using condoms inconsistently during anal sex was associated with syphilis infection. The findings of this survey call for interventions tailored according to the needs of different subsets of MSM.

Notch1 overexpression promotes cell growth and tumor angiogenesis in myeloma

Patients with multiple myeloma (MM) have increased bone marrow angiogenesis, but the angiogenic properties of myeloma cells and the mechanism of MM-induced angiogenesis have not been completely clarified. Notch1 signal has been identified as a critical factor in the regulation of vessel formation. However, the role of Notch1 in the angiogenesis of MM is unclear. We constitutively overexpressed active Notch1 in RPMI8226 cells to explore the effect of Notch1 signaling on cell growth and tumor angiogenesis in vivo and in vitro. We found that Notch1 overexpression promoted myeloma cells growth and increased drug resistance. Moreover, vascular endothelial growth factor (VEGF) expression was increased. Finally, our in vitro results were supported by the in vivo finding in human myeloma xenograft Nonobese diabetic/severe combined immunodeficient (NOD/SCID) models. Notch1 overexpression in MM cells resulted in up-regulation of VEGF expression, promotion of tumor growth, and increased microvessel density (MVD). Our study suggests that Notch1-induced angiogenesis is partly due to activation of VEGF pathway.

hIFN-α gene modification augments human natural killer cell line anti-human hepatocellular carcinoma function

Natural killer (NK) cells are characterized by an efficient antitumor activity, and this activity has been exploited as the basis of cancer immunotherapy strategies. Interferon-α (IFN-α) is an important cytokine required for induction of the durable antitumor immune response and is an important stimulator of NK cells. In this study, to augment the efficiency of NK cell cytotoxicity to tumor cells, human IFN-α gene-modified natural killer cell line (NKL) (NKL-IFNα) cells, which could stably secrete IFN-α, were established. We investigated the natural cytotoxicity of NKL-IFNα cells against human hepatocarcinoma cells (HCCs) in vitro and in vivo. NKL-IFNα cells displayed a significantly stronger cytolytic activity against both human HCC cell lines and primary human hepatoma cancer cells compared with parental NKL cells. The increased cytolytic activity of NKL-IFNα cells was associated with the upregulation of cytotoxicity-related genes, such as perforin, granzyme B and Fas ligand, in the NK cells. Moreover, cytokines secreted by NKL-IFNα cells, such as tumor necrosis factor-α and IFN-γ, induced increased expression of Fas on the target HCC cells, and resulted in increased susceptibility of the HCC cells to NK-mediated cytolysis. Encouragingly, NKL-IFNα cells could significantly inhibit HCC tumor growth in a xenograft model and prolonged the survival of tumor-bearing nude mice. These results suggest that IFN-α gene-modified NKL cells could be suitable for the future development of cell-based immunotherapeutic strategies for hepatocellular carcinoma.

Note: optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence

We report the development of a custom scanning tunneling microscope equipped with photon collection and detection systems. The optical optimization includes the comprehensive design of aspherical lens for light collimation and condensing, the sophisticated piezo stages for in situ lens adjustment inside ultrahigh vacuum, and the fiber-free coupling of collected photons directly onto the ultrasensitive single-photon detectors. We also demonstrate submolecular photon mapping for the molecular islands of porphyrin on Ag(111) under small tunneling currents down to 10 pA and short exposure time down to 1.2 ms/pixel. A high quantum efficiency up to 10(-2) was also observed.

Gestational diabetes, pre-pregnancy obesity and pregnancy weight gain in relation to excess fetal growth: variations by race/ethnicity

AIMS/HYPOTHESIS

The escalating rate of childhood obesity is a public health concern worldwide, with children in certain ethnic groups being disproportionately affected. Our objective was to examine the joint effects of pre-pregnancy adiposity, pregnancy weight gain and gestational diabetes (GDM) in relation to excess fetal growth and to identify susceptible races or ethnic populations.

METHODS

The risk for delivery of a large-for-gestational-age (LGA) infant, specific to race and fetal sex, was evaluated in 105,985 pregnancies in the Consortium on Safe Labor from 2002-2008. Generalised estimating equations were used to estimate the risk for delivery of LGA infants. Joint effects were employed to evaluate the interplay of three risk factors. Models were stratified by racial group considering one, two or three factors (i.e. pre-pregnancy adiposity, pregnancy weight gain and GDM, with 0 factors as the reference group).

RESULTS

Greater pre-pregnancy adiposity, pregnancy weight gain and GDM were independently associated with increased risk of giving birth to an LGA infant across all races (except GDM among non-Hispanic whites), in both underweight and normal-weight women. Among non-Hispanic white, non-Hispanic black and Hispanic women, the three-factor joint effect was associated with substantially increased odds of LGA (OR [95% CI] 11.27 [8.40, 15.11], 7.09 [4.81, 10.45] and 10.19 [6.84, 15.19], respectively). However, for Asian women the joint effect of all three factors (OR [95% CI] 5.14 [2.11, 12.50]) was approximately the same as any of the two factors.

CONCLUSIONS/INTERPRETATION

GDM, pre-pregnancy obesity and excessive pregnancy weight gain were jointly associated with elevated risk of giving birth to an LGA infant and the effects varied by race. This suggests that those involved in public health efforts aimed at preventing LGA deliveries should consider variations in racial groups when devising effective strategies.

Segmentation of clustered nuclei based on concave curve expansion

Segmentation of nuclei from images of tissue sections is important for many biological and biomedical studies. Many existing image segmentation algorithms may lead to oversegmentation or undersegmentation for clustered nuclei images. In this paper, we proposed a new image segmentation algorithm based on concave curve expansion to correctly and accurately extract markers from the original images. Marker-controlled watershed is then used to segment the clustered nuclei. The algorithm was tested on both synthetic and real images and better results are achieved compared with some other state-of-the-art methods.

Epidemiological link between exposure to poultry and all influenza A(H7N9) confirmed cases in Huzhou city, China, March to May 2013

We analysed the association between influenza A(H7N9) confirmed cases and exposure to poultry in Huzhou city, China. All cases (n=12) had a history of direct exposure to poultry or live poultry markets. We detected A(H7N9)-positive poultry samples from each site that was epidemiologically associated with cases. None of the cases’ close contacts tested positive. After closure of the markets, no new cases were identified, suggesting an epidemiological link between poultry exposure and A(H7N9) virus infection.

Epidemiological link between exposure to poultry and all influenza A(H7N9) confirmed cases in Huzhou city, China, March to May 2013

Binary file ES_Abstracts_Final_ECDC.txt matches

Bioreduction and precipitation of uranium in ionic liquid aqueous solution by Clostridium sp

The ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], N-ethylpyridiniumtrifluoroacetate [EtPy][CF3COO] and N-ethylpyridiniumtetrafluoroborate [EtPy][BF4], affected the reduction and precipitation of uranium by Clostridium sp. to a varying degree. Characterization of uranium association with the ionic liquids showed that uranium formed a monodentate complex with the anion BF4(-) and PF6(-) of [EtPy][BF4] and [BMIM][PF6], respectively; and a bidentate complex with carboxylate of [EtPy][CF3COO]. Bioreduction of U(VI) was influenced by the type of complex formed: monodentate complexes were readily reduced whereas the bidentate complex of U(VI) with [CF3COO] was recalcitrant. [EtPy][BF4] affected the rate and extent of precipitation of the reduced uranium; at higher concentration the reduced U(IV) remained in the solution phase. The results suggest that by tuning the properties of ionic liquids they may be valuable candidates for uranium biotreatment.

Foaming Behavior and Mechanical Properties of Microcellular PP/SiO2 Composites

Microcellular foamed polypropylene (PP)/SiO2 composites were prepared by using micro-SiO2 and nano-SiO2 particles. The effects of the particle size of SiO2 on the foaming behavior and mechanical properties of the composites were studied based on heterogeneous nucleation theory. The results showed that the silica facilitated the cell nucleation to some extent. The average cell size of 16.3 μm and the cell density of 4.46 × 107 cells/cm3 were achieved for the composite foam at the silica content of 4 wt.%. The plastic deformation of the PP was strongly constrained due to the presence of the nano-silica. The tensile and impact strength of the nano-SiO2 composite foam are larger than those of the micro-SiO2 composite foam due to the high crack propagation resistance in the microcellular PP/nano-SiO2 composite.