Chimeric mutants of staphylococcal hemolysin, which act as both one-component and two-component hemolysin, created by grafting the stem domain.

Staphylococcus aureus expresses several hemolytic pore-forming toxins (PFTs), which are all commonly composed of three domains: cap, rim and stem. PFTs are expressed as soluble monomers and assemble to form a transmembrane ß-barrel pore in the erythrocyte cell membrane. The stem domain undergoes dramatic conformational changes to form a pore. Staphylococcal PFTs are classified into two groups: one-component α-hemolysin (α-HL) and two-component γ-hemolysin (γ-HL). The α-HL forms a homo-heptamer, whereas γ-HL is an octamer composed of F-component (LukF) and S-component (Hlg2). Because PFTs are used as materials for nanopore-based sensors, knowledge of the functional properties of PFTs is used to develop new, engineered PFTs. However, it remains challenging to design PFTs with a ß-barrel pore because their formation as transmembrane protein assemblies requires large conformational changes. In the present study, aiming to investigate the design principles of the ß-barrel formed as a consequence of the conformational change, chimeric mutants composed of the cap/rim domains of α-HL and the stem of LukF or Hlg2 were prepared. Biochemical characterization and electron microscopy showed that one of them assembles as a heptameric one-component PFT, whereas another participates as both a heptameric one- and heptameric/octameric two-component PFT. All chimeric mutants intrinsically assemble into SDS-resistant oligomers. Based on these observations, the role of the stem domain of these PFTs is discussed. These findings provide clues for the engineering of staphylococcal PFT ß-barrels for use in further promising applications.

The effect of violence in childhood on school success factors in US children.

BACKGROUND: A robust literature-base on adverse childhood experiences (ACEs) provides strong evidence on the relationships between social adversity in childhood and the health and well-being of individuals across the lifespan. One form of social adversity, exposure to violence in childhood, is not only harmful to a child's health and well-being, but detrimental to their performance in school. Poor performance in school may affect educational attainment later in life and hinder a child's upward social mobility. We focus on the impact of violence-related ACEs on school success factors to add new evidence on how violence in childhood affects a child's educational progress. OBJECTIVE: To examine the impact of violence-related ACEs on school success factors, including grade repetition, school absence, and school-home contact. PARTICIPANTS AND SETTINGS: This study uses secondary data analysis of a nationally representative survey, the National Survey of Children's Health (NSCH), to study a sample of non-institutionalized children aged 6-17 in the US (n = 35,122). METHODS: We employed binary logistic regression and multinomial logistic regression using 95% confidence intervals to analyze the effect of violence in childhood on three school success factors, controlling for socio-demographic and health status characteristics. RESULTS: We found that violence in childhood increases the likelihood of grade repetition (OR = 1.47, 95% CI, 1.12-1.92), school-home contact (OR = 2.20, 95% CI, 1.86-2.60), and school absence greater than one week (OR=1.4, 95%CI,1.08-2.00; OR=1.86, 95%CI, 1.36-2.60), controlling for socio-demographic and health status characteristics. CONCLUSIONS: Violence in childhood has a statistically significant negative impact on each of the school success factors included in this study.

Provider Experiences with a Payer-Based PCMH Program.

BACKGROUND: The patient-centered medical home (PCMH) is an enhanced primary care model that aims to improve quality of care. Over the past several years, the PCMH model has been adopted by Medicare and private payers, which offer financial resources and technical assistance to participating practices. However, few studies have examined provider experiences and perspectives on the adoption of payer-based PCMH models in different practice settings. OBJECTIVE: The goal of this qualitative study was to analyze how providers experienced specific elements of a payer-based PCMH model and identify cross-cutting themes that can be applied to other payer-based PCMH initiatives. DESIGN: Observational qualitative study. PARTICIPANTS: A total of 65 individuals (which includes 57 primary care physicians) participated in focus group sessions. Telephone interviews were conducted with an additional 14 physicians and 2 practice administrators. APPROACH: Interviews and focus groups were recorded after obtaining the informed consent of participants. Written transcripts from the recordings were then imported into NVivo 11 for subsequent coding and qualitative analysis of themes. KEY RESULTS: We found that nurse care coordinators (NCCs) were the single most valuable and visible program element. Individual care plans served as effective tools of communication between the NCC and physician on patient care management goals and issues. The online data portal was viewed as the least valuable element. With regard to cross-cutting themes, some providers expressed a strained relationship with CareFirst due to communication challenges, a lack of trust, and differing priorities in selecting patients for care plans. CONCLUSION: Nurse care coordinators and the targeted use of individualized care plans are essential components in a payer-based PCMH program. Improving communication and trust in data reports are critical for effective implementation. Future research should examine provider experiences in other payer-based PCMH programs to see how interactions with payers affect program implementation.

SDS-induced oligomerization of Lys49-phospholipase A2 from snake venom.

Phospholipase A2 (PLA2) is one of the representative toxic components of snake venom. PLA2s are categorized into several subgroups according to the amino acid at position 49, which comprises either Asp49, Lys49, Arg49 or Ser49. Previous studies suggested that the Lys49-PLA2 assembles into an extremely stable dimer. Although the behavior on Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing or non-reducing conditions suggested the presence of intermolecular disulfide bonds, these bonds were not observed in the crystal structure of Lys49-PLA2. The reason for this discrepancy between the crystal structure and SDS-PAGE of Lys49-PLA2 remains unknown. In this study, we analyzed a Lys49-PLA2 homologue from Protobothrops flavoviridis (PflLys49-PLA2 BPII), by biophysical analyses including X-ray crystallography, SDS-PAGE, native-mass spectrometry, and analytical ultracentrifugation. The results demonstrated that PflLys49-PLA2 BPII spontaneously oligomerized in the presence of SDS, which is one of the strongest protein denaturants.