MEASUREMENT OF AMPLITUDE AND DELAY OF STIMULUS FREQUENCY OTOACOUSTIC EMISSIONS

Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.     

Quantitative analysis of hyperpolarized 129Xe ventilation imaging in healthy volunteers and subjects with chronic obstructive pulmonary disease

In this study, hyperpolarized ¹²⁹Xe MR ventilation and ¹H anatomical images were obtained from three subject groups: young healthy volunteers (HVs), subjects with chronic obstructive pulmonary disease (COPD) and age‐matched controls (AMCs). Ventilation images were quantified by two methods: an expert reader‐based ventilation defect score percentage (VDS%) and a semi‐automated segmentation‐based ventilation defect percentage (VDP). Reader‐based values were assigned by two experienced radiologists and resolved by consensus. In the semi‐automated analysis, ¹H anatomical images and ¹²⁹Xe ventilation images were both segmented following registration to obtain the thoracic cavity volume and ventilated volume, respectively, which were then expressed as a ratio to obtain the VDP. Ventilation images were also characterized by generating signal intensity histograms from voxels within the thoracic cavity volume, and heterogeneity was analyzed using the coefficient of variation (CV). The reader‐based VDS% correlated strongly with the semi‐automatically generated VDP (r = 0.97, p < 0.0001) and with CV (r = 0.82, p < 0.0001). Both ¹²⁹Xe ventilation defect scoring metrics readily separated the three groups from one another and correlated significantly with the forced expiratory volume in 1 s (FEV₁) (VDS%: r = –0.78, p = 0.0002; VDP: r = –0.79, p = 0.0003; CV: r = –0.66, p = 0.0059) and other pulmonary function tests. In the healthy subject groups (HVs and AMCs), the prevalence of ventilation defects also increased with age (VDS%: r = 0.61, p = 0.0002; VDP: r = 0.63, p = 0.0002). Moreover, ventilation histograms and their associated CVs distinguished between subjects with COPD with similar ventilation defect scores, but visibly different ventilation patterns. Copyright © 2012 John Wiley & Sons, Ltd.     

Four new C19-diterpenoid alkaloids from Aconitum hemsleyanum var. circinatum

Four new C19-diterpenoid alkaloids, hemaconitines A–D (1–4), were isolated from the roots of Aconitum hemsleyanum var. circinatum. Their structures were elucidated as 19R-hydroxyl-secoyunnaconitine (1), (3R)-hydroxyl-liwaconitine (2), 14-anisoyl-leucanthumsine E (3), and 19R -acetonyl-8-O-methyltalatisamine (4) by extensive spectroscopic analysis (IR, UV, HR-ESI-MS, 1D, and 2D NMR).     

Blocking glutamate‐mediated signalling inhibits human melanoma growth and migration

Glutamate is an excitatory neurotransmitter that has been shown to regulate the proliferation, migration and survival of neuronal progenitors in the central nervous system through its action on metabotropic and ionotropic glutamate receptors (GluRs). Antagonists of ionotropic GluRs have been shown to cause a rapid and reversible change in melanocyte dendritic morphology, which is associated with the disorganization of actin and tubulin microfilaments in the cytoskeleton. Intracellular expression of microtubule‐associated protein (MAP) 2a affects the assembly, stabilization and bundling of microtubules in melanoma cells; stimulates the development of dendrites; and suppresses melanoma cell migration and invasion. In this study, we investigated the relationship between glutamate‐mediated signalling and microtubules, cell dendritic morphology and melanoma cell motility. We found that metabotropic GluR1 and N‐methyl‐d ‐aspartate receptor antagonists increased dendritic branching and inhibited the motility, migration and proliferation of melanoma cells. We also demonstrated that the invasion and motility of melanoma cells are significantly inhibited by the combination of increased expression of MAP2a and either metabotropic GluR1 or N‐methyl‐d ‐aspartate receptor antagonists. Moreover, the blockade of glutamate receptors inhibited melanoma growth in vivo. Collectively, these results demonstrate the importance of glutamate signalling in human melanoma and suggest that the blockade of glutamate receptors is a promising novel therapy for treating melanoma.     

Simvastatin delivery on PEEK for bioactivity and osteogenesis enhancements

Abstract

A strategy developed for obtaining positive cellular responses remains to be focused in the filed of functional biomimetics. In this study, a hydrogel covered simvastatin-loaded polyetheretherketone (PEEK) bio-composites was constructed with the purpose of bone tissue regeneration therapy. Briefly, a three-dimensional (3D) porous structure was fabricated on PEEK surface; then the substrate was functionalized with the poly(L-lactic acid)/simvastatin porous film and hyaluronic acid hydrogel subsequently. In vitro cell attachment, proliferation, and cytoskeletal observation experiments reveal that our scaffolds show better bio-affinity due to the layer of hyaluronic acid hydrogel compared with control. Furthermore, the alkaline phosphatase activity, calcium mineral deposition evaluation, and gene expression for osteogenic potential all exhibit that the superior osteogenic differentiation of MC3T3-E1 pre-osteoblasts on our scaffolds. Therefore, our PEEK samples loaded with simvastatin and covered with hyaluronic acid hydrogel hold great potential in clinical applications for bone repair.     

Social capital in promoting the psychosocial adjustment of chinese migrant children: interaction across contexts

Drawing upon a sample of 772 migrant children and their parents in Shanghai, China, this study investigated how the interactions of social capital embedded in a range of social contexts (i.e., family, school, peer, and community) influenced the psychosocial adjustment of Chinese migrant children. Results of multiple‐group structural equation modeling revealed a moderating effect of community social capital on the associations between other dimensions of social capital and child psychosocial adjustment. Family social capital showed stronger effects when there was higher community social capital, while school social capital appeared to be most influential for children with lower community social capital. Peer social capital showed comparable effects on psychosocial adjustment regardless of the stock of community social capital, but was most important for children with limited resources in both the community and school. Implications of the research findings for theory, practice, policy and future research are discussed. © 2011 Wiley Periodicals, Inc.     

Microbial transformation of asiatic acid by Alternaria longipes

Asiatic acid is a major pentacyclic triterpene isolated from Centella asiatica. It shows a variety of bioactivities. In order to obtain its derivatives, potentially useful for detailed pharmacological studies, the substrate was subjected to incubations with selected micro-organisms. In this work, asiatic acid was converted into three new compounds: 2α,3β,23,30-tetrahydroxyurs-12-ene-28-oic acid (1), 2α,3β,22β,23-tetrahydroxyurs-12-ene-28-oic acid (2), and 2α,3β,22β,23,30-pentahydroxyurs-12-ene-28-oic acid (3) by the fungus Alternaria longipes AS 3.2875. The structures of the three metabolites were determined by 1D and 2D NMR spectral data.