Pulsed-field gel electrophoresis as an epidemiologic tool for enterococci and streptococci

Enterococci (Enterococcus faecium and Enterococcus faecalis) and streptococci such as Streptococcus pyogenes (Group A streptococcus), Streptococcus agalactiae (Group B streptococcus), and Streptococcus pneumoniae are increasing in importance as both hospital-acquired and community pathogens. Emerging resistance and increasing incidence of these organisms has necessitated the analysis of their epidemiologic mechanisms of spread. Pulsed-field gel electrophoresis (PFGE) has emerged as the one of the most widely applicable, reproducible, and stable methods to examine strain identity in bacterial organisms. The procedure used in our laboratory for PFGE typing of whole cell DNA digested with SmaI for enterococci, S. pneumoniae, S. pyogenes, and S. agalacatiae is presented. Issues regarding interpretation are also reviewed and discussed.     

On the kinetics and mechanism of thermal degradation of polystyrene

The thermal degradation of polydisperse polystyrene samples with mol. wts. (M?_n) between 60000 and 22000 has been investigated at different temperatures under oxygen free conditions. Product analysis has been carried out by GPC. The experimental degradation could be simulated by a model consisting of scission and depolymerization. The dynamical behaviour of this model is expressed in a matrix from. The ratio of scission and depolymerization is constant for all polymers and different temperatures during degradation. Therefore, a master curve could be evaluated, which gives a general relation between the decrease of mol. wt. and the mass of volatiles. Finally a radical chain mechanism has been proposed in a lumped form which is consistent with the kinetic model and the experimental results.     

Triplications of chromosome 1p36.3, including the genes GABRD and SKI,are associated with a developmental disorder and a facial gestalt

Triplication of chromosomal region 1p36.3 is a rare genomic rearrangement. In this report, we delineate the phenotypic spectrum associated with 1p36.3 triplications. We describe four patients with microtriplications of variable size, but with a strong phenotypic overlap, and compare them to previously described patients with an isolated triplication or duplication of this region. The 1p36.3 triplication syndrome is associated with a distinct phenotype, characterized by global developmental delay, moderate intellectual disability, seizures, behavioral problems, and specific facial dysmorphic features, including ptosis, hypertelorism, and arched eyebrows. The de novo occurrence of these microtriplications demonstrates the reduced reproductive fitness associated with this genotype, in contrast to 1p36.3 duplications which are mostly inherited and can be associated with similar facial features but with a less severe developmental phenotype. The shared triplicated region encompasses four disease-related genes of which GABRD and SKI are most likely to contribute to the phenotype.     

Controversies in the management of children with bronchiolitis

In this review, we present and summarize data from recently conducted research regarding controversial aspects of the management of children with bronchiolitis. These data suggest that chronic medical history, gestational age at birth, postnatal age, and physiological variables can identify those children at higher risk for a more severe course of bronchiolitis. Large prospective studies also suggest that the likelihood of significant bacterial illness in febrile infants with bronchiolitis may be lower than in children without bronchiolitis. Nevertheless, urinary tract infections remain relatively common in young febrile children with bronchiolitis. Lastly and unfortunately, the data note a relative lack of effective therapies for children with bronchiolitis, although certain therapies such as systemic corticosteroids show potential efficacy and are in need of further study. The remaining uncertainty surrounding many issues pertaining to bronchiolitis highlight the need for more research aimed to: (1) develop prognostic models to identify patients at risk for a more severe clinical course, (2) develop generalizable diagnostic models to identify febrile infants with bronchiolitis at high and very low risk of significant bacterial illness, and (3) evaluate the effectiveness of promising therapies.     

The HOPA Gene Dodecamer Duplication Is Not a Significant Etiological Factor in Autism

A recent study has suggested that a dodecamer duplication in the HOPA gene in Xq13 may occur in a significant portion of male patients with autism. We have determined the incidence of this duplication in 202 patients from the South Carolina Autism Study. The incidence of the duplication was not significantly different between patients and controls. Three of the female patients inherited the duplication from nonautistic fathers. In addition, there was no systematic skewing of X inactivation in the female patients with the duplication, or in nonautistic mothers and sisters with the duplication. These findings suggest that the dodecamer duplication in the HOPA gene does not play a significant role in the etiology of autism.     

Liquid Guayule Natural Rubber,a Sustainable Processing Aid,Enhances the Processability,Durability and Dynamic Mechanical Properties of Rubber Composites

Petroleum-based oils are widely used as processing aids in rubber composites to improve processability but can adversely affect rubber composite performance and increase carbon footprint. In this research, liquid guayule natural rubber (LGNR), produced from guayule natural rubber, was used as a renewable processing aid to replace naphthenic oil (NO) in Hevea natural rubber, styrene-butadiene rubber (SBR) and guayule natural rubber (GNR) composites. The rheological properties, thermal stability, glass transition temperature, dynamic mechanical properties, aging, and ozone resistance of rubber composites with and without NO or LGNR were compared. Natural and synthetic rubber composites made with LGNR had similar processability to those made with NO, but had improved thermal stability, mechanical properties after aging, and ozone resistance. This was due to the strong LGNR–filler interaction and additional crosslinks formed between LGNR and the rubber matrices. The glass transition temperature of SBR composites was reduced by LGNR because of its increased molecular mobility. Thus, unlike NO, LGNR processing aid can simultaneously improve rubber composite durability, dynamic performance and renewability. The commercialization of LGNR has the potential to open a new sustainable processing-aid market.     

Adolescent Knowledge,Attitudes and Practices of Healthy Eating: Findings of Qualitative Interviews among Hong Kong Families

To tackle unhealthy eating among adolescents, it is crucial to understand the dietary knowledge, attitudes, and practices (KAP) on which adolescent eating habits are based. This qualitative study identifies the gaps in KAP by exploring what Chinese adolescents know, perceive, and practice regarding healthy eating to better inform targeted interventions for this important health problem. Parent–adolescent dyads were purposively sampled based on, for example, the dietary intake, age, and gender of the adolescent and household income, and each completed a 30 to 60 min interview. Twelve themes were synthesized: knowledge: (1) dietary recommendations, (2) health outcomes of healthy eating, (3) nutrition content in food, and (4) access to healthy meals; attitudes: (5) outcome expectation for healthy eating, (6) food preferences, and (7) self-efficacy regarding adopting healthy eating; and practices: (8) going grocery shopping for healthy food, (9) eating home-prepared meals. (10) eating out in restaurants or consuming takeaway food, (11) fruit and vegetable consumption, and (12) snacking, perceived unhealthy eating to be low risk, made unhealthy choices regarding snacking and eating out, and had insufficient fruit and vegetable intake. Programs should emphasize the positive short-term health outcomes of healthy eating and empower adolescents to acquire food preparation skills to sustain healthy eating habits.