Specification tests for covariance structures in high-dimensional statistical models

We consider testing the covariance structure in statistical models. We focus on developing such tests when the random vectors of interest are not directly observable and have to be derived via estimated models. Additionally, the covariance specification may involve extra nuisance parameters which also need to be estimated. In a generic additive model setting, we develop and investigate test statistics based on the maximum discrepancy measure calculated from the residuals. To approximate the distributions of the test statistics under the null hypothesis, new multiplier bootstrap procedures with dedicated adjustments that incorporate the model and nuisance parameter estimation errors are proposed. Our theoretical development elucidates the impact due to the estimation errors with high-dimensional data and demonstrates the validity of our tests. Simulations and real data examples confirm our theory and demonstrate the performance of the proposed tests.

Comparative genome/transcriptome analysis probes Boraginales' phylogenetic position, WGDs in Boraginales, and key enzyme genes in the alkannin/shikonin core pathway

Boraginales (the forget-me-not order) is a core group within the lamiids clade. However, until now, no genome from Boraginales has been reported, and published transcriptomes are also rare. Here, we report the first Boraginales species de novo genome (i.e. Echium plantagineum genome) and seven other Boraginales species transcriptomes to probe three issues: (i) Boraginales' phylogenetic position within the lamiids clade; (ii) potential whole genome duplications (WGDs) in Boraginales; and (iii) candidate key enzyme genes in the alkannin/shikonin core pathway. The results showed that: (i) Boraginales was most probably closer to the Solanales/Gentianales clade than the Lamiales clade, at least based on the single-copy orthologous genes from genome/transcriptome data; (ii) after the gamma (γ) event, Boraginaceae (classified into the Boraginales I clade) probably underwent at least two rounds of WGD, whereas Heliotropiaceae and Ehretiaceae (classified into the Boraginales II clade) probably underwent only one round of WGD; and (iii) several candidate key enzyme genes in the alkannin/shikonin core pathway were inferred, e.g. genes corresponding to geranyl cyclase, naphthol hydroxylase and O-acyl transferase.

Water transport properties of boron nitride nanosheets mixed matrix membranes for humic acid removal

Ultrafiltration grade polysulfone-based mixed matrix membranes (MMMs) incorporated with two-dimensional boron nitride nanosheet (BNNS) was prepared via phase inversion method. The amount of BN incorporated was varied and the influence on membrane morphology, contact angle, surface charge, as well as water permeability and humic acid rejection were investigated. Results revealed that the addition of BN to the membrane matrix resulted in profound increase in water permeability (almost tripled to that of neat PSf) and humic acid rejection due to the increase in pore size and surface negative charge. Beyond the morphological changes imparted by the inclusion of BNNS, we postulated that the presence of BNNS within the membrane matrix also contribute to the enhancement in flux and rejection based on surface-slip and selective interlayer transport. Despite the favourable augmentation of water transport and filtration performance, the MMMs suffered with fouling problem due to the entrapment of foulant within the enlarged pores and the membrane valleys. Its inherent adsorptive character could be a disadvantage when utilized as membrane filler.

Routine germline BRCA1 and BRCA2 testing in patients with ovarian carcinoma: analysis of the Scottish real-life experience

OBJECTIVE

To determine the rates of germline BRCA1 and BRCA2 mutations in Scottish patients with ovarian cancer, before and after a change in testing policy.

DESIGN

Retrospective cohort study.

SETTING

Four cancer/genetics centres in Scotland.

POPULATION

Patients with ovarian cancer undergoing germline BRCA1 and BRCA2 (gBRCA1/2) sequencing before 2013 (under the 'old criteria', with selection based solely on family history), after 2013 (under the 'new criteria', with sequencing offered to newly presenting patients with non-mucinous ovarian cancer), and in the 'prevalent population' (who presented before 2013, but were not eligible for sequencing under the old criteria but were sequenced under the new criteria).

METHODS

Clinicopathological and sequence data were collected before and for 18 months after this change in selection criteria.

MAIN OUTCOME MEASURES

Frequency of germline BRCA1, BRCA2, RAD51C, and RAD51D mutations.

RESULTS

Of 599 patients sequenced, 205, 236, and 158 were in the 'old criteria', 'new criteria', and 'prevalent' populations, respectively. The frequency of gBRCA1/2 mutations was 30.7, 13.1, and 12.7%, respectively. The annual rate of gBRCA1/2 mutation detection was 4.2 before and 20.7 after the policy change. A total of 48% (15/31) 'new criteria' patients with gBRCA1/2 mutations had a Manchester score of <15 and would not have been offered sequencing based on family history criteria. In addition, 20 patients with gBRCA1/2 were identified in the prevalent population. The prevalence of gBRCA1/2 mutations in patients aged >70 years was 8.2%.

CONCLUSIONS

Sequencing all patients with non-mucinous ovarian cancer gives a much higher annual gBRCA1/2 mutation detection rate, with the frequency of positive tests still exceeding the 10% threshold upon which many family history-based models operate.

TWEETABLE ABSTRACT

BRCA sequencing all non-mucinous cancer patients increases mutation detection five fold.

Effects of an EPSPS-transgenic soybean line ZUTS31 on root-associated bacterial communities during field growth

The increased worldwide commercial cultivation of transgenic crops during the past 20 years is accompanied with potential effects on the soil microbial communities, because many rhizosphere and endosphere bacteria play important roles in promoting plant health and growth. Previous studies reported that transgenic plants exert differential effects on soil microbial communities, especially rhizobacteria. Thus, this study compared the soybean root-associated bacterial communities between a 5-enolpyruvylshikimate-3-phosphate synthase -transgenic soybean line (ZUTS31 or simply Z31) and its recipient cultivar (Huachun3 or simply HC3) at the vegetative, flowering, and seed-filling stages. High-throughput sequencing of 16S rRNA gene (16S rDNA) V4 hypervariable region amplicons via Illumina MiSeq and real-time quantitative PCR (qPCR) were performed. Our results revealed no significant differences in the overall alpha diversity of root-associated bacterial communities at the three developmental stages and in the beta diversity of root-associated bacterial communities at the flowering stage between Z31 and HC3 under field growth. However, significant differences in the beta diversity of rhizosphere bacterial communities were found at the vegetative and seed-filling stages between the two groups. Furthermore, the results of next generation sequencing and qPCR showed that the relative abundances of root-associated main nitrogen-fixing bacterial genera, especially Bradyrhizobium in the roots, evidently changed from the flowering stage to the seed-filling stage. In conclusion, Z31 exerts transitory effects on the taxonomic diversity of rhizosphere bacterial communities at the vegetative and seed-filling stages compared to the control under field conditions. In addition, soybean developmental change evidently influences the main symbiotic nitrogen-fixing bacterial genera in the roots from the flowering stage to the seed-filling stage.

NLRP3 inflammasome pathway has a critical role in the host immunity against clinically relevant Acinetobacter baumannii pulmonary infection

The opportunistic Gram-negative bacterium Acinetobacter baumannii (AB) is a leading cause of life-threatening nosocomial pneumonia. Outbreaks of multidrug resistant (MDR)-AB belonging to international clones (ICs) I and II with limited treatment options are major global health threats. However, the pathogenesis mechanisms of various AB clonal groups are understudied. Although inflammation-associated interleukin-1β (IL-1β) levels and IL-1 receptor antagonist polymorphisms were previously implicated in MDR-AB-related pneumonia in patients, whether inflammasomes has any role in the host defense and/or pathogenesis of clinically relevant A. baumannii infection is unknown. Using a sublethal mouse pneumonia model, we demonstrate that an extensively drug-resistant clinical isolate (ICII) of A. baumannii exhibits reduced/delayed early pulmonary neutrophil recruitment, higher lung persistence, and, most importantly, elicits enhanced IL-1β/IL-18 production and lung damage through NLRP3 inflammasome, in comparison with A. baumannii-type strain. A. baumannii infection-induced IL-1β/IL-18 production is entirely dependent on NLRP3-ASC-caspase-1/caspase-11 pathway. Using Nlrp3^-/- mice infection models, we further show that while NLRP3 inflammasome pathway contributes to host defense against A. baumannii clinical isolate, it is dispensable for protection against A. baumannii-type strain. Our study reveals a novel differential role for NLRP3 inflammasome pathway in the immunity against clinically relevant A. baumannii infections, and highlights inflammasome pathway as a potential immunomodulatory target.

Naphthoquinones: A continuing source for discovery of therapeutic antineoplastic agents

Naturally occurring naphthoquinones, usually in forms of botanical extracts, have been implicated with human life since ancient time, far earlier than their isolation and identification in modern era. The long use history of naphthoquinones has witnessed their functional shift from the original purposes as dyes and ornaments toward medicinal benefits. Hitherto, numerous studies have been carried out to elucidate the pharmacological profile of both natural and artificial naphthoquinones. A number of entities have been identified with promising therapeutic potential. Apart from the traditional effects of wound healing, anti-inflammatory, hemostatic, antifertility, insecticidal and antimicrobial, etc., the anticancer potential of naphthoquinones either in combination with other treatment approaches or on their own is being more and more realized. The molecular mechanisms of naphthoquinones in cells mainly fall into two categories as inducing oxidant stress by ROS (reactive oxygen species) generation and directly interacting with traditional therapeutic targets in a non-oxidant mechanism. Based on this knowledge, optimized agents with naphthoquinones scaffold have been acquired and further tested. Hereby, we summarize the explored biological mechanisms of naphthoquinones in cells and review the application perspective of promising naphthoquinones in cancer therapies.

Involvement of LeMDR, an ATP-binding cassette protein gene, in shikonin transport and biosynthesis in Lithospermum erythrorhizon

BACKGROUND

Shikonin is a naphthoquinone secondary metabolite with important medicinal value and is found in Lithospermum erythrorhizon. Considering the limited knowledge on the membrane transport mechanism of shikonin, this study investigated such molecular mechanism.

RESULTS

We successfully isolated an ATP-binding cassette protein gene, LeMDR, from L. erythrorhizon. LeMDR is predominantly expressed in L. erythrorhizon roots, where shikonin accumulated. Functional analysis of LeMDR by using the yeast cell expression system revealed that LeMDR is possibly involved in the shikonin efflux transport. The accumulation of shikonin is lower in yeast cells transformed with LeMDR-overexpressing vector than that with empty vector. The transgenic hairy roots of L. erythrorhizon overexpressing LeMDR (MDRO) significantly enhanced shikonin production, whereas the RNA interference of LeMDR (MDRi) displayed a reverse trend. Moreover, the mRNA expression level of LeMDR was up-regulated by treatment with shikonin and shikonin-positive regulators, methyl jasmonate and indole-3-acetic acid. There might be a relationship of mutual regulation between the expression level of LeMDR and shikonin biosynthesis.

CONCLUSIONS

Our findings demonstrated the important role of LeMDR in transmembrane transport and biosynthesis of shikonin.

Novel mechanisms for organic acid-mediated aluminium tolerance in roots and leaves of two contrasting soybean genotypes

Aluminium (Al) toxicity is one of the most important limiting factors for crop yield in acidic soils. However, the mechanisms that confer Al tolerance still remain largely unknown. To understand the molecular mechanism that confers different tolerance to Al, we performed global transcriptome analysis to the roots and leaves of two contrasting soybean genotypes, BX10 (Al-tolerant) and BD2 (Al-sensitive) under 0 and 50 μM Al3+ treatments, respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that the expression levels of the genes involved in lipid/carbohydrate metabolism and jasmonic acid (JA)-mediated signalling pathway were highly induced in the roots and leaves of both soybean genotypes. The gene encoding enzymes, including pyruvate kinase, phosphoenolpyruvate carboxylase, ATP-citrate lyase and glutamate-oxaloacetate transaminase 2, associated with organic acid metabolism were differentially expressed in the BX10 roots. In addition, the genes involved in citrate transport were differentially expressed. Among these genes, FRD3b was down-regulated only in BD2, whereas the other two multidrug and toxic compound extrusion genes were up-regulated in both soybean genotypes. These findings confirmed that BX10 roots secreted more citrate than BD2 to withstand Al stress. The gene encoding enzymes or regulators, such as lipoxygenase, 12-oxophytodienoate reductase, acyl-CoA oxidase and jasmonate ZIM-domain proteins, involved in JA biosynthesis and signalling were preferentially induced in BD2 leaves. This finding suggests that the JA defence response was activated, possibly weakening the growth of aerial parts because of excessive resource consumption and ATP biosynthesis deficiency. Our results suggest that the Al sensitivity in some soybean varieties could be attributed to the low level of citrate metabolism and exudation in the roots and the high level of JA-mediated defence response in the leaves.

Transcriptome analysis explores genes related to shikonin biosynthesis in Lithospermeae plants and provides insights into Boraginales' evolutionary history

Shikonin and its derivatives extracted from Lithospermeae plants' red roots have current applications in food and pharmaceutical industries. Previous studies have cloned some genes related to shikonin biosynthesis. However, most genes related to shikonin biosynthesis remain unclear, because the lack of the genome/transcriptome of the Lithospermeae plants. Therefore, in order to provide a new understanding of shikonin biosynthesis, we obtained transcriptome data and unigenes expression profiles in three shikonin-producing Lithospermeae plants, i.e., Lithospermum erythrorhizon, Arnebia euchroma and Echium plantagineum. As a result, two unigenes (i.e., G10H and 12OPR) that are involved in "shikonin downstream biosynthesis" and "methyl jasmonate biosynthesis" were deemed to relate to shikonin biosynthesis in this study. Furthermore, we conducted a Lamiids phylogenetic model and identified orthologous unigenes under positive selection in above three Lithospermeae plants. The results indicated Boraginales was more relative to Solanales/Gentianales than to Lamiales.

Identification of New Shikonin Derivatives as Antitumor Agents Targeting STAT3 SH2 Domain

Signal transducer and activator of transcription 3 (STAT3) is hyper-activated in diversiform human tumors and has been validated as an attractive therapeutic target. Current research showed that a natural product, shikonin, along with its synthetic analogues, is able to inhibit the activity of STAT3 potently. The potential space of shikonin in developing novel anti-cancer agents encouraged us to carry out the investigation of the probable binding mode with STAT3. From this foundation, we have designed new types of STAT3 SH2 inhibitors. Combined simulations were performed to filter for the lead compound, which was then substituted, synthesized and evaluated by a variety of bioassays. Among the entities, PMM-172 exhibited the best anti-proliferative activity against MDA-MB-231 cells with IC₅₀ value 1.98 ± 0.49 μM. Besides, it was identified to decrease luciferase activity, induce cell apoptosis and reduce mitochondrial transmembrane potential in MDA-MB-231 cells. Also, PMM-172 inhibited constitutive/inducible STAT3 activation without affecting STAT1 and STAT5 in MDA-MB-231 cells, and had no effect in non-tumorigenic MCF-10A cells. Moreover, PMM-172 suppressed STAT3 nuclear localization and STAT3 downstream target genes expression. Overall, these results indicate that the antitumor activity of PMM-172 is at least partially due to inhibition of STAT3 in breast cancer cells.

Impact of a Glyphosate-Tolerant Soybean Line on the Rhizobacteria, Revealed by Illumina MiSeq

The global commercial cultivation of transgenic crops, including glyphosate-tolerant soybean, has increased widely in recent decades with potential impact on the environment. The bulk of previous studies showed different results on the effects of the release of transgenic plants on the soil microbial community, especially rhizosphere bacteria. In this study, comparative analyses of the bacterial communities in the rhizosphere soils and surrounding soils were performed between the glyphosate-tolerant soybean line NZL06-698 (or simply N698), containing a glyphosate-insensitive EPSPS gene, and its control cultivar Mengdou12 (or simply MD12), by a 16S ribosomal RNA gene (16S rDNA) amplicon sequencing-based Illumina MiSeq platform. No statistically significant difference was found in the overall alpha diversity of the rhizosphere bacterial communities, although the species richness and evenness of the bacteria increased in the rhizosphere of N698 compared with that of MD12. Some influence on phylogenetic diversity of the rhizosphere bacterial communities was found between N698 and MD12 by beta diversity analysis based on weighted UniFrac distance. Furthermore, the relative abundances of part rhizosphere bacterial phyla and genera, which included some nitrogen-fixing bacteria, were significantly different between N698 and MD12. Our present results indicate some impact of the glyphosate-tolerant soybean line N698 on the phylogenetic diversity of rhizosphere bacterial communities together with a significant difference in the relative abundances of part rhizosphere bacteria at different classification levels as compared with its control cultivar MD12, when a comparative analysis of surrounding soils between N698 and MD12 was used as a systematic contrast study.

Synthesis, characterization and biological evaluation of formononetin derivatives as novel EGFR inhibitors via inhibiting growth, migration and inducing apoptosis in breast cancer cell line

Novel formononetin derivative 4v inhibited MDA-MB-231 cell proliferation, migration and induced apoptosis through targeting EGFR.

Cerebral [18 F]T807/AV1451 retention pattern in clinically probable CTE resembles pathognomonic distribution of CTE tauopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder most commonly associated with repetitive traumatic brain injury (TBI) and characterized by the presence of neurofibrillary tangles of tau protein, known as a tauopathy. Currently, the diagnosis of CTE can only be definitively established postmortem. However, a new positron emission tomography (PET) ligand, [¹⁸F]T807/AV1451, may provide the antemortem detection of tau aggregates, and thus various tauopathies, including CTE. Our goal was to examine [¹⁸F]T807/AV1451 retention in athletes with neuropsychiatric symptoms associated with a history of multiple concussions. Here we report a 39-year-old retired National Football League player who suffered 22 concussions and manifested progressive neuropsychiatric symptoms. Emotional lability and irritability were the chief complaints. Serial neuropsychological exams revealed a decline in executive functioning, processing speed and fine motor skills. Naming was below average but other cognitive functions were preserved. Structural analysis of longitudinally acquired magenetic resonance imaging scans revealed cortical thinning in the left frontal and lateral temporal areas, as well as volume loss in the basal ganglia. PET with [¹⁸F]florbetapir was negative for amyloidosis. The [¹⁸F]T807/AV1451 PET showed multifocal areas of retention at the cortical gray matter-white matter junction, a distribution considered pathognomonic for CTE. [¹⁸F]T807/AV1451 standard uptake value (SUV) analysis showed increased uptake (SUVr⩾1.1) in bilateral cingulate, occipital, and orbitofrontal cortices, and several temporal areas. Although definitive identification of the neuropathological underpinnings basis for [¹⁸F]T807/AV1451 retention requires postmortem correlation, our data suggest that [¹⁸F]T807/AV1451 tauopathy imaging may be a promising tool to detect and diagnose CTE-related tauopathy in living subjects.

Comparison of miRNAs and Their Targets in Seed Development between Two Maize Inbred Lines by High-Throughput Sequencing and Degradome Analysis

MicroRNAs (miRNAs) play an important role in plant growth, development, and response to environment. For identifying and comparing miRNAs and their targets in seed development between two maize inbred lines (i.e. PH6WC and PH4CV), two sRNAs and two degradome libraries were constructed. Through high-throughput sequencing and miRNA identification, 55 conserved and 24 novel unique miRNA sequences were identified in two sRNA libraries; moreover, through degradome sequencing and analysis, 137 target transcripts corresponding to 38 unique miRNA sequences were identified in two degradome libraries. Subsequently, 16 significantly differentially expressed miRNA sequences were verified by qRT-PCR, in which 9 verified sequences obviously target 30 transcripts mainly involved with regulation in flowering and development in embryo. Therefore, the results suggested that some miRNAs (e.g. miR156, miR171, miR396 and miR444) related reproductive development might differentially express in seed development between the PH6WC and PH4CV maize inbred lines in this present study.

The LIKE SEX FOUR2 regulates root development by modulating reactive oxygen species homeostasis in Arabidopsis

Maintaining reactive oxygen species (ROS) homeostasis plays a central role in plants, and is also critical for plant root development. Threshold levels of ROS act as signals for elongation and differentiation of root cells. The protein phosphatase LIKE SEX FOUR2 (LSF2) has been reported to regulate starch metabolism in Arabidopsis, but little is known about the mechanism how LSF2 affect ROS homeostasis. Here, we identified that LSF2 function as a component modulating ROS homeostasis in response to oxidative stress and, thus regulate root development. Compared with wild type Arabidopsis, lsf2-1 mutant exhibited reduced rates of superoxide generation and higher levels of hydrogen peroxide upon oxidative stress treatments. The activities of several antioxidant enzymes, including superoxide dismutase, catalase, and ascorbate peroxidase, were also affected in lsf2-1 mutant under these oxidative stress conditions. Consequently, lsf2-1 mutant exhibited the reduced root growth but less inhibition of root hair formation compared to wild type Arabidopsis plants. Importantly, protein phosphatase LSF2 interacted with mitogen-activated protein kinase 8 (MPK8), a known component of ROS homeostasis pathways in the cytoplasm. These findings indicated the novel function of LSF2 that controls ROS homeostasis to regulate root development.

[Safety and efficacy of Cox-maze Ⅲ procedure for patients with atrial fibrillation associated with rheumatic mitral valve disease]

OBJECTIVE

To evaluate the safety and efficacy of cut-and-sew Cox-Maze (CM) Ⅲ procedure for patients with atrial fibrillation associated with rheumatic mitral valve disease.

METHODS

Patients received mitral valve replacement and CM procedure between January 2007 and July 2015, were 1∶1 matched and assigned to CM Ⅳ group (undergoing surgical ablation) and CM Ⅲ group (undergoing cut-and-sew CM Ⅲ). Safety indices, mortality rate, complications and recovery rate of sinus rhythm were compared between the two groups.

RESULTS

Mean extracorporeal circulation time was (154±22) min in the CM Ⅲ group and (136±21) min in the CM Ⅳ group (P<0.001), and aortic clamp time was (85±9) min in the CM Ⅲ group and (74±12) min in the CM Ⅳ group (P<0.001). One patient (1.18%) in the CM Ⅲ group died of multi-organ failure 4 day after left ventricular rupture being sucessfully repaired, and 2 patients died (2.35%) in the CM Ⅳ group ( 1 due to left ventricular rupture and 1 due to low cardiac output syndrome). There was no significant difference in mortality between the two groups. Temporary pacemaker were applied for 76 cases (89.41%) in the CM Ⅲ and 70 cases (82.35%) in the CM Ⅳ group, without a statistical difference (P=0.186). There were also no statistical difference between the two groups in intraoperative urinary volume, postoperative drainage of fluid volume, hemoglobinuria, ventilator time, ICU time, hospital stay and the incidence of the complications (all P>0.05). Sinus rhythm recovery rate was 62.35 % in the CM Ⅲ group and 57.65 % in the CM Ⅳ group, without a statistical difference (P=0.531) at the operation day, but at discharge a statistical difference was found (97.62% in the CM Ⅲ group vs 81.93% in the CM Ⅳ group, P<0.001). All patients were followed up for three months, and no deaths occurred. Sinus rhythm recovery rate was 96.43 % in the CM Ⅲ group and 86.75% in the CM Ⅳ group, with a statistical difference (P=0.024).

CONCLUSION

The cut-and-sew Cox-Maze Ⅲ procedure is a safe and effective method for patients with atrial fibrillation associated with rheumatic mitral valve disease.

A Classic Near-Infrared Probe Indocyanine Green for Detecting Singlet Oxygen

The revelation of mechanisms of photodynamic therapy (PDT) at the cellular level as well as singlet oxygen (¹O₂) as a second messengers requires the quantification of intracellular ¹O₂. To detect singlet oxygen, directly measuring the phosphorescence emitted from ¹O₂ at 1270 nm is simple but limited for the low quantum yield and intrinsic efficiency of ¹O₂ emission. Another method is chemically trapping ¹O₂ and measuring fluorescence, absorption and Electron Spin Resonance (ESR). In this paper, we used indocyanine green (ICG), the only near-infrared (NIR) probe approved by the Food and Drug Administration (FDA), to detect ¹O₂in vitro. Once it reacts with ¹O₂, ICG is decomposed and its UV absorption at 780 nm decreases with the laser irradiation. Our data demonstrated that ICG could be more sensitive and accurate than Singlet Oxygen Sensor Green reagent^® (SOSG, a commercialized fluorescence probe) in vitro, moreover, ICG functioned with Eosin Y while SOSG failed. Thus, ICG would reasonably provide the possibility to sense ¹O₂in vitro, with high sensitivity, selectivity and suitability to most photosensitizers.

Clinical and immunochemical profiles of food challenge proven or anaphylactic shrimp allergy in tropical Singapore

BACKGROUND

Shellfish allergy in Singapore is highly prevalent, and shrimp allergy is the most common.

OBJECTIVE

This study aims to evaluate the clinical characteristics and immunological phenotype of shellfish allergy in this population.

METHODS

Patients with self-reported shellfish allergy were recruited from outpatient clinics of three large hospitals and from a population survey. Open oral food challenges (OFC) to glass prawn (Litopenaeus vannamei) and tiger prawn (Penaeus monodon) were carried out on all patients except for those who had a history of severe anaphylaxis. Skin prick tests (SPT) and specific IgE to crude and recombinant allergens were carried out to evaluate shrimp and dust mite sensitization. Immunoblots were used to assess IgE-binding proteins.

RESULTS

The 104 patients recruited were categorized into shellfish allergic (SA) when OFC was positive or had a history of severe anaphylaxis (n = 39), shellfish tolerant (ST) when OFC was negative (n = 27), and house dust mite positive controls (HDM(+) ) who were ST (n = 38). Oral symptoms (87.1%) were the predominant clinical manifestation. Positive challenge doses ranged from 2 to 80 g of cooked shrimp, with 25/52 patients reacting to either one or both shrimps challenged. The presence of specific IgE to shrimp either by SPT and/or ImmunoCAP(®) assay provided diagnostic test sensitivity of 82% and specificity of 22.2%. The inclusion of specific IgE to shrimp tropomyosin and IgE immunoblots with shrimp extracts did not improve the diagnostic proficiency substantially.

CONCLUSIONS AND CLINICAL RELEVANCE

This study highlights the predominance of oral symptoms in shrimp allergy in tropical Asia and that a high provocation dose may be necessary to reveal shrimp allergy. Furthermore, specific IgE diagnostic tests and immunoblots were of limited use in this population.

An energy adjustable linearly polarized passively Q-switched bulk laser with a wedged diffusion-bonded Nd:YAG/Cr⁴⁺:YAG crystal

An energy adjustable passively Q-switched laser is demonstrated with a composite Nd:YAG/Cr⁴⁺:YAG crystal by applying a wedged interface inside the crystal. The theoretical model of the monolithic laser resonator is explored to show the energy adjustable feature with different initial transmissions of the saturable absorber at the horizontal axis. By adjusting the pump beam location across the Nd:YAG crystal, the output pulse energy can be flexibly changed from 10.9 μJ to 17.6 μJ while maintaining the same output efficiency. The polarization state of the laser output is found to be along with the polarization of the C-mount pump diode. Finally, the behavior of the multi-transverse-mode oscillation is also discussed for eliminating the instability of the pulse train.

A potent anticancer agent of shikonin derivative targeting tubulin

In this study, a shikonin ester derivative, compound , was selected to evaluate its anticancer activities and we found that compound exhibited better antitubulin activities against the human HepG2 cell line with an IC50 value of 1.097 μM. Furthermore, the inhibition of tubulin polymerization results indicated that compound demonstrated the most potent antitubulin activity (IC50  = 13.88), which was compared with shikonin and colchicine as positive controls (IC50  = 25.28 μM and 22.56 μM), respectively. Compound was simulated to have good binding site with tubulin and arrested the cell cycle at G2/M phase, which also induces apoptosis in HepG2 cells, in which P53 and members of Bcl-2 protein family were both involved in the progress of apoptosis revealed by western blot. Confocal microscopy observations revealed compound targeted tubulin and altered its polymerization by interfering with microtubule organization. Based on these results, compound functions as a potent anticancer agent targeting tubulin.

Regulation of neural responses to emotion perception by ketamine in individuals with treatment-resistant major depressive disorder

The glutamate N-methyl-D-aspartate receptor antagonist ketamine has demonstrated antidepressant effects in individuals with treatment-resistant major depressive disorder (TRD) within 24 h of a single dose. The current study utilized functional magnetic resonance imaging (fMRI) and two separate emotion perception tasks to examine the neural effects of ketamine in patients with TRD. One task used happy and neutral facial expressions; the other used sad and neutral facial expressions. Twenty patients with TRD free of concomitant antidepressant medication underwent fMRI at baseline and 24 h following administration of a single intravenous dose of ketamine (0.5 mg kg(-1)). Adequate data were available for 18 patients for each task. Twenty age- and sex-matched healthy volunteers were scanned at one time point for baseline comparison. Whole-brain, voxel-wise analyses were conducted controlling for a family-wise error rate (FWE) of P<0.05. Compared with healthy volunteers, TRD patients showed reduced neural responses to positive faces within the right caudate. Following ketamine, neural responses to positive faces were selectively increased within a similar region of right caudate. Connectivity analyses showed that greater connectivity of the right caudate during positive emotion perception was associated with improvement in depression severity following ketamine. No main effect of group was observed for the sad faces task. Our results indicate that ketamine specifically enhances neural responses to positive emotion within the right caudate in depressed individuals in a pattern that appears to reverse baseline deficits and that connectivity of this region may be important for the antidepressant effects of ketamine.

Identification of miRNAs and their targets in transgenic Brassica napus and its acceptor (Westar) by high-throughput sequencing and degradome analysis

MicroRNAs (miRNAs) are a class of noncoding small RNAs (sRNAs) that play many roles in plant growth, development, and the stress response.

First Report of Acrostalagmus luteo-albus Causing Red Rust of Needle Mushroom (Flammulina velutipes) in China

Needle mushroom (Flammulina velutipes) is an edible and medicinal mushroom with annual production yields for China exceeding 2 million metric tons. Hebei province is one of the biggest producers of needle mushrooms in China. From 2009 to 2010, red rust-colored sporulation (fungal mycelia and conidia) was found on the substrate surface of white needle mushroom bags in more than 10 mushroom cultivation operations in Hebei. The rust-colored sporulation covered the substrate surface, where the development of the fruiting bodies was inhibited; the stipes were sparse and became light brown when the substrate was slightly affected. The fruiting bodies on severely affected substrate were unable to complete development or shriveled and died off on the substrate. More than 30 to 40% substrate bags were contaminated with the red rust mold, with approximately a 40% yield reduction in each production house. Single conidia were isolated from the red rust mold and cultured on potato dextrose agar at 25°C in the dark. The colony was round, compact, reddish-brown, and slow-growing (2 to 3 mm/d). Main conidiophore axes were erect, often branched in five to seven layers, tapered from the base to the upper part, pale reddish brown at the base, and almost hyaline at the apex. Two to five phialides usually verticillated at each level along the main stipe and its branches. Phialides were narrowly flask-shaped and only very slightly swollen at the base. Conidia were oval, measured 3.5 to 5.4 (4.5) × 2.3 to 3.6 (3.0) μm, L/W = 1.2 to 2.0 (1.5), and formed pale reddish brown, slimy heads. The isolate was tentatively identified as Acrostalagmus luteo-albus based on its morphological characteristics (2). For molecular analysis, the internal transcribed spacer (ITS) regions of ribosomal DNA from the isolate were PCR-amplified using universal primers ITS1 and ITS4. The resulting sequence (Accession No. KC127681) submitted to GenBank had a 99% identity to that of A. luteo-albus (JN545827) isolated from vineyard soil and Accession No. JQ387575 isolated from twig of declining persimmon tree. To confirm the pathogenicity of the isolate to needle mushroom, five bags of needle mushroom with stipes of 1 to 2 cm long were inoculated with a conidia suspension (10⁵ conidia/ml) of the isolate and incubated at 13 to 15°C in the dark, while five non-inoculated bags (sprayed with sterile water only) were used as a control. Five days after inoculation, the development of the fruiting body was obviously inhibited, and a few growing fruiting bodies became light brown, compared with the non-inoculated fruiting bodies, which were growing healthily and fast and were white with no symptoms. The pathogen was re-isolated from the inoculated fruiting bodies. A. luteo-albus is primarily saprophytic but is sometimes pathogenic. Indeed, it has been associated with post-harvest rot of ginger rhizomes in Brazil (1). To our knowledge, this is the first report of A. luteo-albus causing damage to needle mushroom in China. References: (1) S. I. Moreira et al. Trop. Plant Pathol. 38:218, 2013. (2) R. Zare et al. Mycol. Res. 108:576, 2004.

Targeted photosensitizer nanoconjugates based on human serum albumin selectively kill tumor cells upon photo-irradiation

Small and non-toxic nanoconjugates RGD–HSA–Ce6 could provide targeted and effective photodynamic therapy of tumor cells.

Voxel-based approach to generate entire human metacarpal bone with microscopic architecture for finite element analysis

With the development of micro-computed tomography (micro-CT) technology, it is possible to construct three-dimensional (3D) models of human bone without destruction of samples and predict mechanical behavior of bone using finite element analysis (FEA). However, due to large number of elements required for constructing the FE models of entire bone, this demands a substantial computational effort and the analysis usually needs a high level of computer. In this article, a voxel-based approach for generation of FE models of entire bone with microscopic architecture from micro-CT image data is proposed. To enable the FE analyses of entire bone to be run even on a general personal computer, grayscale intensity thresholds were adopted to reduce the amount of elements. Human metacarpal bone (MCP) bone was used as an example for demonstrating the applicability of the proposed method. The micro-CT images of the MCP bone were combined and converted into 3D array of pixels. Dual grayscale intensity threshold parameters were used to distinguish the pixels of bone tissues from those of surrounding soft tissues and improve predictive accuracy for the FE analyses with different sizes of elements. The method of selecting an appropriate value of the second grayscale intensity threshold was also suggested to minimize the area error for the reconstructed cross-sections of a FE structure. Experimental results showed that the entire FE MCP bone with microscopic architecture could be modeled and analyzed on a personal computer with reasonable accuracy.

Efficient high-power terahertz beating in a dual-wavelength synchronously mode-locked laser with dual gain media

We originally present a novel tactic to accomplish a compact efficient dual-wavelength synchronously mode-locked laser by physically combining the Nd:YVO4 crystal to the Nd:GdVO4 crystal as a composite gain medium. With the developed method, the total output power at 1.06 μm could be effectually produced to reach 1.3 W under the optimally balanced two-color intensities. The corresponding mode-locked pulse width and repetition rate are measured to be 47 ps and 2.86 GHz, respectively. Through the optical beating between two carrier frequencies of dual-color synchronous pulses, a train of 0.32 THz ultrashort pulses is further generated with the effective duration of down to 1.6 ps.

High-power tunable single- and multi-wavelength diode-pumped Nd:YAP laser in the (4)F3/2 → (4)I11/2 transition

We experimentally explore the fluorescent spectrum of the Nd:YAP crystal to manifest the feasibility of tunable single- and multi-wavelength operations in the (4)F3/2 → (4)I11/2 transition. An intracavity etalon is subsequently exploited to effectively select spectral lines at 1073, 1080, and 1084 nm with the tunabilities of 0.56, 1.13, and 0.1 nm, respectively. We also experimentally obtain multi-wavelength oscillations among various intermanifold lines in the Nd:YAP crystal with the output powers on the order of several watts for each group. Employing the Cr(4+):YAG crystal to realize the passively Q-switched operation, the maximum average output powers as high as 2.3 and 3.5 W for 1073 and 1080 nm are obtained. The corresponding pulse energies at 1073 and 1080 nm are up to 177 and 159 μJ, respectively.

Efficient high-energy passively Q-switched Nd:YLF/Cr4+:YAG UV laser at 351 nm with pulsed pumping in a nearly hemispherical cavity

We originally utilize a nearly hemispherical cavity to accomplish the energy scale-up for a high-repetition-rate nanosecond pulsed pumped Nd:YLF laser passively Q-switched by the Cr(4+):YAG saturable absorber. This compact laser is able to efficiently generate pulse energy as large as 1.38 mJ and pulse width as short as 5 ns under a pulse repetition rate of 100 Hz. Further employing the developed Nd:YLF laser to perform extracavity harmonic generations, the maximum pulse energies of 490 μJ at 527 nm and 360 μJ at 351 nm are achieved with the shortest pulse duration of 4 ns.

Tunable GHz pulse repetition rate operation in high-power TEM(00)-mode Nd:YLF lasers at 1047 nm and 1053 nm with self mode locking

We report on a high-power diode-pumped self-mode-locked Nd:YLF laser with the pulse repetition rate up to several GHz. A novel tactic is developed to efficiently select the output polarization state for achieving the stable TEM(00)-mode self-mode-locked operations at 1053 nm and 1047 nm, respectively. At an incident pump power of 6.93 W and a pulse repetition rate of 2.717 GHz, output powers as high as 2.15 W and 1.35 W are generated for the σ- and π-polarization, respectively. We experimentally find that decreasing the separation between the gain medium and the input mirror not only brings in the pulse shortening thanks to the enhanced effect of the spatial hole burning, but also effectively introduces the effect of the spectral filtering to lead the Nd:YLF laser to be in a second harmonic mode-locked status. Consequently, pulse durations as short as 8 ps and 8.5 ps are obtained at 1053 nm and 1047 nm with a pulse repetition rate of 5.434 GHz.

Parameter optimization for the visco-hyperelastic constitutive model of tendon using FEM

Numerous constitutive models describing the mechanical properties of tendons have been proposed during the past few decades. However, few were widely used owing to the lack of implementation in the general finite element (FE) software, and very few systematic studies have been done on selecting the most appropriate parameters for these constitutive laws. In this work, the visco-hyperelastic constitutive model of the tendon implemented through the use of three-parameter Mooney-Rivlin form and sixty-four-parameter Prony series were firstly analyzed using ANSYS FE software. Afterwards, an integrated optimization scheme was developed by coupling two optimization toolboxes (OPTs) of ANSYS and MATLAB for estimating these unknown constitutive parameters of the tendon. Finally, a group of Sprague-Dawley rat tendons was used to execute experimental and numerical simulation investigation. The simulated results showed good agreement with the experimental data. An important finding revealed that too many Maxwell elements was not necessary for assuring accuracy of the model, which is often neglected in most open literatures. Thus, all these proved that the constitutive parameter optimization scheme was reliable and highly efficient. Furthermore, the approach can be extended to study other tendons or ligaments, as well as any visco-hyperelastic solid materials.

Alterations of white matter tracts following neurotoxic hippocampal lesions in macaque monkeys: a diffusion tensor imaging study

Diffusion tensor imaging (DTI) is a valuable tool for assessing presumptive white matter alterations in human disease and animal models. The current study used DTI to examine the effects of selective neurotoxic lesions of the hippocampus on major white matter tracts and anatomically related brain regions in macaque monkeys. Two years postlesion, structural MRI, and DTI sequences were acquired for each subject. Volumetric assessment revealed a substantial reduction in the size of the hippocampus in experimental subjects, averaging 72% relative to controls, without apparent damage to adjacent regions. DTI images were processed to yield measures of fractional anisotropy (FA), apparent diffusion coefficient (ADC), parallel diffusivity (lADC), and perpendicular diffusivity (tADC), as well as directional color maps. To evaluate potential changes in major projection systems, a region of interest (ROI) analysis was conducted including the corpus callosum, fornix, temporal stem, cingulum bundle, ventromedial prefrontal white matter, and optic radiations. Lesion-related abnormalities in the integrity of the fiber tracts examined were limited to known hippocampal circuitry, including the fornix and ventromedial prefrontal white matter. These findings are consistent with the notion that hippocampal damage results in altered interactions with multiple memory-related brain regions, including portions of the prefrontal cortex.

Determination of Lycopene in Dietary Supplements and Raw Materials by High-Performance Liquid Chromatography: Collaborative Study

A collaborative study was conducted to evaluate the interlaboratory performance of an LC method for lycopene in dietary supplements and the raw materials commonly used in their manufacture. Twelve laboratories from six countries agreed to participate in the study. Results from 10 laboratories were received and are reported. Five dietary supplements, including both tablets and a softgel capsule with a lycopene content ranging from 25 g to 25 mg per unit, and three raw materials, including gelatin-based beadlets, vegetarian beadlets, and a suspension in oil ranging from 5 to 20 lycopene, were analyzed as blind duplicates. In addition to the commercial products, two positive controls and a negative control were included in the study. For the raw materials studied, the repeatability relative standard deviations (RSDr) ranged from 1.49 to 5.13 for total lycopene, and the reproducibility relative standard deviations (RSDR) ranged from 3.84 to 9.21 with HorRat values from 1.23 to 3.24. For finished products, the RSDr ranged from 1.31 to 4.62, RSDR from 4.28 to 10.5, and HorRat values from 0.79 to 2.07. Corresponding values for all-trans-lycopene were significantly higher. It is recommended that the method be considered for Official First Action for all-trans- and total lycopene in finished products and raw materials.

Comments on "Viscoelastic studies of human subscapularis tendon: relaxation test and a Wiechert model" by C. Machiraju, A.V. Phan, A.W. Pearsall, S. Madanagopal, Computer Methods and Programs in Biomedicine (2006)

Referring to the approach for determining the material parameters for a Wiechert model of the human subscapularis tendon proposed by Machiraju et al. [C. Machiraju, A.V. Phan, A.W. Pearsall, S. Madanagopal, Viscoelastic studies of a human subscapularis tendon: relaxation test and a Wiechert model, Computer Methods and Programs in Biomedicine (2006), doi:10.1016/j.cmpb.2006.05.004], some comments are made on the basis of the result of an alternative method that is capable of giving more reasonable values for the Wiechart model with the fitting discrepancies minimized by a multi-variable optimization strategy.

Microsatellite DNA markers for population-genetic studies of blue mackerel (Scomber australasicus) and cross-specific amplification in S. japonicus

Blue mackerel (Scomber australasicus) is targeted by large-scale purse-seiners in the western North Pacific, and its stock structure is still contentious. Herein, we described 10 polymorphic microsatellite loci for blue mackerel. The number of alleles among 32 individuals surveyed ranged from five to 27 (average of 16.2 alleles per locus). Departures from Hardy-Weinberg expectation were observed at two loci. Cross-specific amplification in the congener, S. japonicus, was successful, except for one locus, revealed to be diagnostic for these congeners. These microsatellite loci will be useful tools to address queries in population genetic structure, fishery management unit and taxonomic species status in the genus Scomber.

Immediate food hypersensitivity among adults attending a clinical immunology/allergy centre in Singapore

INTRODUCTION

The patient characteristics, clinical features and causative foods in 74 consecutive adult patients with immediate food hypersensitivity were studied.

METHODS

A retrospective review of 74 consecutive adults who presented during the study period from July 1, 1994 to April 30, 2002 was performed.

RESULTS

There were 35 male and 39 female patients, with a mean age of 36.3 +/- 10.9 (range, 19-66) years. The most common causative foods were seafood crustaceans, molluscs and bird's nest. Prawn and crab were the most commonly implicated crustacean, and limpet the commonest culprit mollusc. The main symptoms were periorbital angioedema (64.9 percent), dyspnoea/wheezing (44.6 percent) and urticaria (44.6 percent). 66 percent of the patients developed anaphylaxis. 34 (45.9 percent) had concomitant allergic rhinoconjunctivitis, asthma, eczema or combinations of these atopic diseases. Only six (8.1 percent) patients had a family history of food allergy. Skin prick tests (SPT) to commercially-prepared food allergens were positive in 22 of 36 patients (61.1 percent) tested. SPT to the fresh, cooked or canned food products were positive in 11 of 20 (55 percent) cases where the food allergen was not commercially available. Open food challenges were required for diagnosis in two patients who had negative SPT.

CONCLUSION

The most common food allergens in our patients were seafood crustaceans, molluscs and bird's nest. More than half of the patients had concomitant allergic rhinitis, asthma and/or eczema. The pattern of food allergy in Singapore differs from Caucasian populations, likely to be because of different regional dietary patterns and methods of food preparation.

Image deconvolution in spherical aberration-corrected high-resolution transmission electron microscopy

The method of image deconvolution developed previously for FEG high-resolution transmission electron microscope (HRTEM) without a spherical aberration (C(s)) corrector was for the first time applied to FEG HRTEM with a C(s)-corrector. The principle and the procedure of image deconvolution are briefly described. Four qualified [1 1 0] images of Si were selected from a through-focus series to perform image deconvolution. The projected potential is successfully derived from all the images, and the obtained "dumbbell" structure maps of Si [1 1 0] are in good agreement with the calculated potential map. The criterion of selecting qualified images for performing image deconvolution is indicated. The possibility of applying image deconvolution to defect study and to ab initio crystal structure determination is discussed.

Anaphylaxis in adults referred to a clinical immunology/allergy centre in Singapore

INTRODUCTION

To study the clinical features and causes of anaphylaxis in consecutive adult patients referred to a clinical immunology/allergy centre in Singapore.

METHODS

A retrospective review of 67 consecutive adults with anaphylaxis who presented from July 1, 1998 to February 28, 2002 was performed. Anaphylaxis was defined as a severe life-threatening systemic IgE-mediated hypersensitivity reaction. Non-steroidal anti-inflammatory drug-induced idiosyncratic reactions and other non-IgE mediated reactions were excluded. Hypotension and bronchospasm were not required to make a diagnosis. The aetiology was determined from clinical history followed by measurement of allergen-specific IgE levels, skin prick test with commercially-available allergen extracts or prick-prick test with the fresh/cooked/canned food products.

RESULTS

The mean age of patients was 32.9 +/- 10.9 (range 19-57) years. There were 44 (65.7 percent) males and 23 (34.3 percent) females. The main causes were food (44.8 percent), insect stings (32.8 percent) and idiopathic (22.4 percent). There were no cases due to drugs or natural rubber latex. Seafood (crustaceans and molluscs) comprised 66.7 percent of food-induced anaphylaxis. Honeybee and wasp stings together comprised 45 percent of insect venom anaphylaxis. The most common manifestations were dyspnoea (59.7 percent), urticaria (58.2 percent), angioedema (44.8 percent), and syncope (43.3 percent). Hypotension was documented in only 28.4 percent of cases.

CONCLUSION

Food (crustaceans and molluscs) was the most common cause followed by insect stings or bites. The inability to identify the causative insect in 50 percent of cases with insect venom anaphylaxis limited the role of specific immunotherapy. Compared to other reported series, there were no cases of drug or latex anaphylaxis.

Why generic and disease-specific quality-of-life instruments should be used together for the evaluation of patients with persistent allergic rhinitis

BACKGROUND

The importance of assessing health-related quality of life (HRQL) of patients with allergic rhinitis (AR) has been well established, but the specific roles of rhinitis-specific or general health instruments have not been delineated.

OBJECTIVE

We analysed the psychometric properties of a disease-specific instrument, the Rhinoconjunctivitis Quality-of-Life Questionnaire (RQLQ) and the general health instrument, the Medical Outcome Short-Form 36 (SF-36) as they are employed in combination in patients with persistent AR in clinical practice.

METHOD

We analysed the data collected from a prospective study of 43 newly diagnosed patients with persistent AR and 44 controls. We interviewed the patients four times, at baseline, weeks 4, 8 and 10.

RESULTS

The RQLQ and SF-36 have good discriminative property, internal consistency, and test-retest reliability. The RQLQ is superior to the SF-36 as an evaluative instrument because more of its domains respond to change, the magnitude of change was greater, and the response was faster. The SF-36 is more susceptible to floor and ceiling effects. Both instruments are unsuitable for mildly symptomatic patients based on Rasch model analysis. Each questionnaire assesses a distinct and significant portion of the total HRQL of persistent AR.

CONCLUSION

The SF-36 and RQLQ are good for discriminating rhinitis patients from controls, but the former is poor for detecting changes in QOL. Both are inappropriate for mildly symptomatic patients. Each instrument measures non-overlapping halves of the measurable HRQL. For an assessment of the HRQL in persistent AR that is complete and responsive both instruments should be employed together.

Modeling of muscle fatigue using Hill's model

A new model incorporating muscle fatigue has been developed to predict the effect of muscle fatigue on the force-time relationship of skeletal muscle by using the PAK-program. Differential equations in the incremental form have been implemented into Hill's muscle model. In order to describe the effect of muscle fatigue and recovery on skeletal muscle behaviors, a set of equations in terms of three phenomenological parameters which are a fatigue curve under sustained maximal activation, a recovery curve and an endurance function were developed. With reference to existing models and experimental results, the input parameters for fatigue curve under sustained maximal activation and endurance function were determined. The model has been investigated under an isometric condition. The effects of different shapes of the recovery curves have also been considered in this model. Validation of the model has been performed by comparing the predicted results with the experimental data from an existing literature.

Influence of interphase layer on the overall elasto-plastic behaviors of HA/PEEK biocomposite

A three-dimensional finite element unit cell model has been designed and constructed for studying mechanical properties of hydroxyapatite (HA) reinforced polyetheretherketone (PEEK) biocomposite. The model consists of an elastic-brittle HA spherical particle, an elasto-plastic matrix and an interphase layer between the particle and the matrix. The interphase layers with four different kinds of material behaviors have been taken into consideration to examine their effects on the overall properties of the composite. The damage evolution in the matrix and the interphase layer, and the interface failure, were also taken into account. Some other factors, such as mesh sensitivity, loading velocity and mass scale scheme, were also discussed in this investigation. A general-purpose finite element software package, ABAQUS, incorporated with a user-defined material subroutine, was used to perform the analysis. The predicted results were compared with the experimental data obtained from existing literatures. The results predicted by using the cell model with consideration of the matrix degradation and the effects of the damage and failure on the interphase layer are in good agreement with the experimental ones. Hence, the suitability of our proposed cell model incorporated with an appropriate type of the interphase layer for modeling the mechanical properties of the particulate biocomposite could be verified.

Active finite element analysis of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction

An active finite element model was developed to predict the mechanical behaviors of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction. The active finite element was created through incorporation of a user-defined material property into ABAQUS finite element code. The active finite element is controlled by a motor element that is activated by a mathematical function. The nonlinear passive behavior of the muscle was defined by the viscoelastic elements and can be easily altered to other properties by using other elements in the material library without the need of re-defining the constitutive relation of the muscle. The isometric force-length relationship, force-strain relations of the muscle-tendon complex during both shortening and lengthening contraction and muscle relaxation response were predicted using the proposed finite element model. The predicted results were found to be in good agreement with available experimental data. In addition, the stress distribution in the muscle-tendon complex during isometric, shortening and lengthening contractions was simulated. The location of the maximum stress may provide useful information for studying muscle damage and fatigue in the future.

Neuroactive steroids reduce neuronal excitability by selectively enhancing tonic inhibition mediated by delta subunit-containing GABAA receptors

Neuroactive steroids are potent modulators of gamma-aminobutyric acid type A receptors (GABAARs), and their behavioral effects are generally viewed in terms of altered inhibitory synaptic transmission. Here we report that, at concentrations known to occur in vivo, neuroactive steroids specifically enhance a tonic inhibitory conductance in central neurons that is mediated by extrasynaptic delta subunit-containing GABAARs. The neurosteroid-induced augmentation of this tonic conductance decreases neuronal excitability. Fluctuations in the circulating concentrations of endogenous neuroactive steroids have been implicated in the genesis of premenstrual syndrome, postpartum depression, and other anxiety disorders. Recognition that delta subunit-containing GABAARs responsible for a tonic conductance are a preferential target for neuroactive steroids may lead to novel pharmacological approaches for the treatment of these common conditions.

Wear performance of ultrahigh molecular weight polyethylene/quartz composites

Ultrahigh molecular weight polyethylene (UHMWPE)/quartz composites were compression molded in the presence of organosiloxane, and then hydrolyzed. The used organosiloxane is vinyl tri-ethyloxyl silane. The gelation, the melting behavior, the crystallinity, the mechanical properties and the wear resistance of UHMWPE/quartz composites were investigated. The results showed that organosiloxane can act as a cross-linking agent for UHMWPE matrix and serve as a coupling agent for improving the bonding between the quartz particles and the UHMWPE matrix. The correlation between the various properties and the morphology of the composites has been discussed. At about 0.5phr organsiloxane while the degree of crystallinity of the composite is at the peak value of 57%, the mechanical properties and the wear resistance of UHMWPE/quartz composites reaches their maximum.