Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends

Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones-Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.

Characterization of two novel gene cassettes, dfrA27 and aadA16, in a non-O1, non-O139 Vibrio cholerae isolate from China

Two novel integron-borne cassettes, dfrA27 (encoding trimethoprim resistance) and aadA16 (encoding streptomycin and spectinomycin resistance), located on a conjugative plasmid, have been found in a non-O1, non-O139 Vibrio cholera isolate. DfrA27 shares 75% amino acid identity with DfrA5, and AadA16 shares 88% identity with AdaA6. Cloning of the cassette region and expression analysis demonstrated that the aadA16 gene can be expressed from its own promoter sequence, which is present upstream of the aadA16 cassette.

Visualizing CD4 T-cell migration into inflamed skin and its inhibition by CCR4/CCR10 blockades using in vivo imaging model

BACKGROUND

Chemokines are critical mediators of T-cell homing into inflamed skin. The complex nature of this multicellular response makes it difficult to analyse mechanisms mediating the early responses in vivo.

OBJECTIVES

To visualize directly T-cell homing into inflamed skin and its inhibition by blockades using a unique noninvasive confocal microscopy.

MATERIALS AND METHODS

A mouse model of allergic contact dermatitis was used. T cells from oxazolone-sensitized and -challenged Balb/c mice were first analysed phenotypically in vitro. CD4 T cells were then labelled with a tracker dye and transferred into Balb/c-SCID mice. The recipient mice were challenged with oxazolone and CD4 T-cell homing into inflamed skin was visualized.

RESULTS

T cells with the skin homing receptors CCR4 and CCR10 were increased in the affected skin and draining lymph nodes, and effectively attracted by their specific chemokines CCL17, CCL22 and CCL27 in vitro. Using in vivo imaging, T-cell migration into the inflamed skin was observed at 2 h after application, peaking at 12 h and continuing for 48 h. Simultaneous systemic administration of neutralizing antibodies against CCR4 ligands (CCL17 and CCL22) and CCR10 ligand (CCL27) led to a significant suppression of T-cell migration and skin inflammation.

CONCLUSIONS

Our data indicate that these tissue-selective adhesion molecules and chemokine/receptor pathways act in concert to attract specialized T-cell populations to mediate cutaneous inflammation. The in vivo imaging technique can be applicable to other models of cutaneous diseases to help with better understanding of the pathogenesis and monitoring the therapeutic effects.

Increased expression of activation-induced cytidine deaminase is associated with anti-CCP and rheumatoid factor in rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with higher levels of autoantibodies and IL-17. Here, we investigated if ectopic lymphoid follicles and peripheral blood mononuclear cells (PBMCs) from RA patients exhibit increased activation-induced cytidine deaminase (AID), and if increased AID is correlated with serum levels of autoantibodies and IL-17. The results of immunohistochemical staining showed that organized AID(+) germinal centres were observed in six of the 12 RA synovial samples, and AID(+) cells were found almost exclusively in the B-cell areas of these follicles. Aggregated but not organized lymphoid follicles were found in only one OA synovial sample without AID(+) cells. Significantly higher levels of AID mRNA (Aicda) detected by RT-PCR were found in the PBMCs from RA patients than PBMCs from normal controls (P < 0.01). In the PBMCs from RA patients, AID was expressed predominately by the CD10(+)IgM(+)CD20(+) B-cell population and the percentage of these cells that expressed AID was significantly higher than in normal controls (P < 0.01). AID expression in the PBMCs correlated significantly and positively with the serum levels of rheumatoid factor (RF) (P </= 0.0001) and anti-cyclic citrullinated peptide (CCP) (P = 0.0005). Serum levels of IFN-gamma (P = 0.0005) and IL-17 (P = 0.007), but not IL-4, also exhibited positive correlation with the expression of AID. These results suggest that the higher levels of AID expression in B cells of RA patients correlate with, and may be associated with the higher levels of T helper cell cytokines IFN-gamma and IL-17, leading to the development of anti-CCP and RF.

Depression and low bone mineral density: a meta-analysis of epidemiologic studies

SUMMARY

The association between depression and loss of bone mineral density (BMD) has been reported inconsistently. This meta-analysis, which pooled results from 14 qualifying individual studies, found that depression was associated with a significantly decreased BMD, with a substantially greater BMD decrease in depressed women and in cases of clinical depression.

INTRODUCTION

The reported association between depression and loss of BMD has been controversial. This meta-analysis was conducted to determine whether depression and BMD are associated and to identify the variation in some subgroups.

METHODS

English-language articles published before October 2008 were used as the data source. A total of six case-controlled and eight cross-sectional studies met prestated inclusion criteria (N = 10,523). Information on study design, participant characteristics, measurements of BMD and depression, and control for potential confounders was abstracted independently by two investigators using a standardized protocol.

RESULTS

Overall, depression was associated with a significant decrease in mean BMD of spine (-0.053 g/cm(2) [95% confidence interval {CI} -0.087 to -0.018 g/cm(2)]) and hip (-0.052 g/cm(2) [95% CI -0.083 to -0.022 g/cm(2)]). A substantially greater BMD decrease was observed in depressed women (-0.076 g/cm(2) in spine; -0.059 g/cm(2) in hip) and in cases of clinical depression (-0.074 g/cm(2) in spine; -0.080 g/cm(2) in hip).

CONCLUSION

Depression is associated with low BMD, with a substantially greater BMD decrease in depressed women and in cases of clinical depression. Depression should be considered as an important risk factor for osteoporosis.

Chemistry and quality of Hibiscus (Hibiscus sabdariffa) for developing the natural-product industry in Senegal

The objectives of this study were to assess and improve the quality of the hibiscus calyces from Senegal over 2 production seasons (2004 to 2005), to develop and adapt new procedures for the determination of hibiscus anthocyanins and analysis of the 2 major ones, delphinidin-3-sambubioside and cyanidin-3-sambubioside. The foreign matter, total ashes, and acid insoluble ashes showed that the calyces harvested in 2005 were produced following hygienic practices, while the color assessment of the calyces and analysis of hibiscus active principles also showed higher amounts of anthocyanins in 2005. A protocol to measure anthocyanins by pH-differential UV-Vis spectrophotometry was adapted to measure the hibiscus anthocyanins from a water extract. The spectrophotometric method for quantitation of total anthocyanins showed a close correlation (r(2)= 0.82) when compared with the HPLC method, suggesting the use of the colorimetric method in quality control programs as an affordable alternative method to assess anthocyanin content in hibiscus. New and raised standards for the cleanliness and active principle content in hibiscus are also proposed. This study demonstrated that the implementation of a quality control program and the application of agricultural good practices in the production and processing of hibiscus calyces can lead to higher quality natural plant products.

Direct visualization of optical frequency invisibility cloak based on silicon nanorod array

A new invisibility cloak was recently proposed for hiding objects in front of a highly reflecting mirror. This cloak requires only modest values of optical constants with minimal anisotropy and thus can be implemented by using non-resonant dielectric materials, making it an ideal system for optical frequency operation. We implemented the cloak using an array of silicon nanorods fabricated by electron-beam lithography. We then directly visualized the cloaking effect by monitoring the light propagation inside the device using the near-field optical microscopy.

A low dose of Mycoplasma pneumoniae infection enhances an established allergic inflammation in mice: the role of the prostaglandin E2 pathway

BACKGROUND

Over 40% of chronic stable asthma patients have evidence of respiratory Mycoplasma pneumoniae (Mp) infection as detected by PCR, but not by serology and culture, suggesting that a low-level Mp is involved in chronic asthma. However, the role of such a low-level Mp infection in the regulation of allergic inflammation remains unknown.

OBJECTIVE

To determine the impact of a low-level Mp infection in mice with established airway allergic inflammation on allergic responses such as eosinophilia and chemokine eotaxin-2, and the underlying mechanisms [i.e. the prostaglandin E(2) (PGE(2)) pathway] since PGE(2) inhalation before an allergen challenge suppressed the eosinophil infiltration in human airways.

METHODS

BALB/c mouse models of ovalbumin (OVA)-induced allergic asthma with an ensuing low- or high-dose Mp were used to assess IL-4 expression, bronchoalveolar lavage (BAL) eosinophil, eotaxin-2 and PGE(2) levels, and lung mRNA levels of microsomal prostaglandin E synthase-1 (mPGES-1). Primary alveolar macrophages (pAMs) from naïve BALB/c mice were cultured to determine whether Mp-induced PGE(2) or exogenous PGE(2) down-regulates IL-4/IL-13-induced eotaxin-2.

RESULTS

Low-dose Mp in allergic mice significantly enhanced IL-4 and eotaxin-2, and moderately promoted lung eosinophilia, whereas high-dose Mp significantly reduced lung eosinophilia and tended to decrease IL-4 and eotaxin-2. Moreover, in both OVA-naïve and allergic mice, lung mPGES-1 mRNA and BAL PGE(2) levels were elevated in mice infected with high-dose, but not low-dose Mp. In pAMs, IL-4/IL-13 significantly increased eotaxin-2, which was reduced by Mp infection accompanied by dose-dependent PGE(2) induction. Exogenous PGE(2) inhibited IL-4/IL-13-induced eotaxin-2 in a dose-dependent manner.

CONCLUSIONS

This study highlights a novel concept on how different bacterial loads in the lung modify the established allergic airway inflammation and thus interact with an allergen to further induce Th2 responses. That is, unlike high-level Mp, low-level Mp fails to effectively induce PGE(2) to down-regulate allergic responses (e.g. eotaxin-2), thus maintaining or even worsening allergic inflammation in asthmatic airways.