Multiple-relaxation-time discrete Boltzmann modeling of multicomponent mixture with nonequilibrium effects

A multiple-relaxation-time discrete Boltzmann model (DBM) is proposed for multicomponent mixtures, where compressible, hydrodynamic, and thermodynamic nonequilibrium effects are taken into account. It allows the specific heat ratio and the Prandtl number to be adjustable, and is suitable for both low and high speed fluid flows. From the physical side, besides being consistent with the multicomponent Navier-Stokes equations, Fick's law, and Stefan-Maxwell diffusion equation in the hydrodynamic limit, the DBM provides more kinetic information about the nonequilibrium effects. The physical capability of DBM to describe the nonequilibrium flows, beyond the Navier-Stokes representation, enables the study of the entropy production mechanism in complex flows, especially in multicomponent mixtures. Moreover, the current kinetic model is employed to investigate nonequilibrium behaviors of the compressible Kelvin-Helmholtz instability (KHI). The entropy of mixing, the mixing area, the mixing width, the kinetic and internal energies, and the maximum and minimum temperatures are investigated during the dynamic KHI process. It is found that the mixing degree and fluid flow are similar in the KHI process for cases with various thermal conductivity and initial temperature configurations, while the maximum and minimum temperatures show different trends in cases with or without initial temperature gradients. Physically, both heat conduction and temperature exert slight influences on the formation and evolution of the KHI morphological structure

Molecular epidemiology and nasal carriage of Staphylococcus aureus and methicillin-resistant S. aureus among young children attending day care centers and kindergartens in Hong Kong

OBJECTIVES: To investigate the prevalence and molecular epidemiology of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) nasal carriage in children. METHODS: We collected nasal and nasopharyngeal swabs from 2211 children aged 2-5 years attending 79 day care centers (DCCs) and 113 kindergartens (KGs) in all 18 geographical districts in Hong Kong. RESULTS: The overall carriage rates of S. aureus and MRSA were 27.6% (95% confidence interval [CI], 24.8-28.5%) and 1.3% (95% CI, 0.8-1.8%), respectively. Molecular typing (staphylococcal cassette chromosome mec [SCCmec], sequence type [ST], clonal cluster [CC]) showed that all the 28 MRSA isolates had SCCmec IV (n = 13) or V (n = 15) including 12 isolates with community-associated-MRSA genotypes (ST59-IV/V, ST30-IV and ST88-V), 10 isolates with healthcare-associated-MRSA genotypes (ST45-IV/V, CC5-IV and ST630-V) and six isolates with novel genotypes (ST10-V and CC1-IV). Spa typing indicated that there was some within and between DCCs/KGs transmission of certain MRSA and methicillin-sensitive S. aureus strains but this was not extensive. CONCLUSION: Our findings indicate the potential for DCCs to be a reservoir for emerging MRSA genotypes and highlight the need to enhance education and infection control measures to reduce their cross-transmission in this population.postprin

Molecular epidemiology and nasal carriage of Staphylococcus aureus and methicillin-resistant S. aureus among young children attending day care centers and kindergartens in Hong Kong

OBJECTIVES: To investigate the prevalence and molecular epidemiology of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) nasal carriage in children. METHODS: We collected nasal and nasopharyngeal swabs from 2211 children aged 2-5 years attending 79 day care centers (DCCs) and 113 kindergartens (KGs) in all 18 geographical districts in Hong Kong. RESULTS: The overall carriage rates of S. aureus and MRSA were 27.6% (95% confidence interval [CI], 24.8-28.5%) and 1.3% (95% CI, 0.8-1.8%), respectively. Molecular typing (staphylococcal cassette chromosome mec [SCCmec], sequence type [ST], clonal cluster [CC]) showed that all the 28 MRSA isolates had SCCmec IV (n = 13) or V (n = 15) including 12 isolates with community-associated-MRSA genotypes (ST59-IV/V, ST30-IV and ST88-V), 10 isolates with healthcare-associated-MRSA genotypes (ST45-IV/V, CC5-IV and ST630-V) and six isolates with novel genotypes (ST10-V and CC1-IV). Spa typing indicated that there was some within and between DCCs/KGs transmission of certain MRSA and methicillin-sensitive S. aureus strains but this was not extensive. CONCLUSION: Our findings indicate the potential for DCCs to be a reservoir for emerging MRSA genotypes and highlight the need to enhance education and infection control measures to reduce their cross-transmission in this population.postprin

An update on the human and animal enteric pathogen Clostridium perfringens

Clostridium perfringens, a rapid-growing pathogen known to secrete an arsenal of >20 virulent toxins, has been associated with intestinal diseases in both animals and humans throughout the past century. Recent advances in genomic analysis and experimental systems make it timely to re-visit this clinically and veterinary important pathogen. This Review will summarise our understanding of the genomics and virulence-linked factors, including antimicrobial potentials and secreted toxins of this gut pathogen, and then its up-to-date clinical epidemiology and biological role in the pathogenesis of several important human and animal-associated intestinal diseases, including pre-term necrotising enterocolitis. Finally, we highlight some of the important unresolved questions in relation to C. perfringens-mediated infections, and implications for future research directions

Unusual cause of a painful right testicle in a 16-year-old man: a case report

<p>Abstract</p> <p>Introduction</p> <p>Urgent surgical exploration of the scrotum of a child or teenager who presents with a painful and swollen testicle is paramount if testicular torsion is not to be missed. It is extremely rare for a non-scrotal pathology to present with acute scrotal signs. Here we present such a rare case and emphasize the importance of being aware of this potential clinical pitfall.</p> <p>Case presentation</p> <p>A 16-year-old Caucasian man presented as a surgical emergency with a five to six hour history of a painful, red, and swollen right hemiscrotum. He also complained of vague lower abdominal pain, vomiting, and watery diarrhea. He had a temperature of 38.5°C and a tender, red, and swollen right hemiscrotum. The right testicle appeared elevated. He was mildly tender in his central and upper abdomen and less so in the lower abdomen. No convincing localizing abdominal signs were noted. He had an increased white cell count (15 × 10⁹/L) and C-reactive protein (CRP; 300 mg/L). Urgent right hemiscrotal exploration revealed about 5 ml of pus in the tunica vaginalis and a normal testicle. A right iliac fossa incision identified the cause: a perforated retrocecal appendix. Appendectomy was performed, and both the abdomen and scrotum washed copiously with saline before closure. The patient made an uneventful recovery.</p> <p>Conclusion</p> <p>Acute appendicitis presenting with scrotal signs due to a patent processus vaginalis is an extremely rare clinical entity. To date, fewer than five such cases have been reported in the medical literature. It is, therefore, extremely important to be aware of this unusual clinical scenario, as only a high index of suspicion will enable prompt, successful management of both the appendicitis and the scrotal abscess.</p

The putative Tumor Suppressor VILIP-1 Counteracts Epidermal Growth Factor-Induced Epidermal-Mesenchymal Transition in Squamous Carcinoma Cells

Epithelial-mesenchymal transition (EMT) is a crucial step for the acquisition of invasive properties of carcinoma cells during tumor progression. Epidermal growth factor (EGF)-treatment of squamous cell carcinoma (SCC) cells provokes changes in the expression of lineage markers, morphological changes, and a higher invasive and metastatic potential. Here we show that chronic stimulation with EGF induces EMT in skin-derived SCC cell lines along with the down-regulation of the epithelial marker E-cadherin, and of the putative tumor suppressor VILIP-1 (visinin-like protein 1). In esophageal squamous cell carcinoma and non-small cell lung carcinoma the loss of VILIP-1 correlates with clinicopathological features related to enhanced invasiveness. VILIP-1 has previously been shown to suppress tumor cell invasion via enhancing cAMP-signaling in a murine SCC model. In mouse skin SCC cell lines the VILIP-1-negative tumor cells have low cAMP levels, whereas VILIP-1-positive SCCs possess high cAMP levels, but low invasive properties. We show that in VILIP-1-negative SCCs, Snail1, a transcriptional repressor involved in EMT, is up-regulated. Snail1 expression is reduced by ectopic VILIP-1-expression in VILIP-1-negative SCC cells, and application of the general adenylyl cyclase inhibitor 2′,3′-dideoxyadenosine attenuated this effect. Conversely, EGF-stimulation of VILIP-1-positive SCC cells leads to the down-regulation of VILIP-1 and the induction of Snail1 expression. The induction of Snail is inhibited by elevated cAMP levels. The role of cAMP in EMT was further highlighted by its suppressive effect on the EGF-induced enhancement of migration in VILIP-1-positive SCC cells. These findings indicate that VILIP-1 is involved in EMT of SCC by regulating the transcription factor Snail1 in a cAMP-dependent manner

Child, Maternal and Demographic Factors Influencing Caregiver-Reported Autistic Trait Symptomatology in Toddlers.

Current research on children's autistic traits in the general population relies predominantly on caregiver-report, yet the extent to which individual, caregiver or demographic characteristics are associated with informants' ratings has not been sufficiently explored. In this study, caregivers of 396 Singaporean two-year-olds from a birth cohort study completed the Quantitative Checklist for Autism in Toddlers. Children's gender, cognitive functioning and birth order, maternal age, and ethnic group membership were not significant predictors of caregiver-reported autistic traits. Poorer child language development and higher maternal depressive symptoms significantly predicted more social-communicative autistic traits, while lower maternal education predicted more behavioural autistic traits. Children's language and informants' educational level and depressive symptomatology may need to be considered in caregiver-reports of autistic traits.This research is supported by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Flagship Programme and administered by the Singapore Ministry of Health’s National Medical Research Council (NMRC), Singapore—NMRC/TCR/004-NUS/2008 and NMRC/TCR/012-NUHS/2014. Additional funding was provided by the Ministry of Education AcRF Tier 1 funding grant R581000130112 awarded to the corresponding/senior author and Singapore Institute for Clinical Sciences—A*STAR

Core Site-Moiety Maps Reveal Inhibitors and Binding Mechanisms of Orthologous Proteins by Screening Compound Libraries

Members of protein families often share conserved structural subsites for interaction with chemically similar moieties despite low sequence identity. We propose a core site-moiety map of multiple proteins (called CoreSiMMap) to discover inhibitors and mechanisms by profiling subsite-moiety interactions of immense screening compounds. The consensus anchor, the subsite-moiety interactions with statistical significance, of a CoreSiMMap can be regarded as a “hot spot” that represents the conserved binding environments involved in biological functions. Here, we derive the CoreSiMMap with six consensus anchors and identify six inhibitors (IC50<8.0 µM) of shikimate kinases (SKs) of Mycobacterium tuberculosis and Helicobacter pylori from the NCI database (236,962 compounds). Studies of site-directed mutagenesis and analogues reveal that these conserved interacting residues and moieties contribute to pocket-moiety interaction spots and biological functions. These results reveal that our multi-target screening strategy and the CoreSiMMap can increase the accuracy of screening in the identification of novel inhibitors and subsite-moiety environments for elucidating the binding mechanisms of targets