Maturational and social factors contributing to relative age effects in school sports: Data from the London Youth Games.

Few studies have investigated whether relative age effects (RAEs) exist in school sport. None have sought to test the competing maturational and social-agent hypotheses proposed to explain the RAE. We aimed to determine the presence of RAEs in multiple school sports and examine the contribution of maturational and social factors in commonplace school sports. We analyzed birth dates of n=10645 competitors (11-18 years) in the 2013 London Youth Games annual inter-school multisport competition and calculated odds ratio (OR) for students competing based on their yearly birth quarter (Q1-Q4). Multivariate logistic regression was used to determine the relative contribution of constituent year (Grade) and relative age in netball and football which used multiyear age groupings. In girls, RAEs were present in the team sports including hockey, netball, rugby union, cricket and volleyball but not football. In boys, RAEs were stronger in common team sports (football, basketball cricket) as well as athletics and rowing. In netball and football teams with players from two constituent years, birth quarter better-predicted selection than did constituent year. Relatively older players (Q1) from lower constituent years were overrepresented compared with players from Q3 and Q4 of the upper constituent years. RAEs are present in the many sports commonplace in English schools. Selection of relatively older players ahead of chronologically older students born later in the selection year suggests social agents contribute to RAEs in school sports.

The duration of fecal Salmonella shedding following clinical disease among dairy cattle in the northeastern USA.

The objectives of this study were to determine the duration of fecal Salmonella shedding among dairy cattle in the northeastern United States following laboratory-confirmed clinical disease and to evaluate whether age group or serotype was associated with either shedding period or mortality. Study farms included 22 dairy herds that had at least two previous salmonellosis cases confirmed by fecal culture. Veterinarians continued to submit culture samples from clinical suspects following herd enrollment, and fecal samples from positive cattle were collected monthly until three sequential negative results were obtained or until loss to follow-up. There were 357 culture-positive clinical cases that each involved a single serotype during the shedding period. The Kaplan-Meier median duration of fecal Salmonella shedding was 50 days, and the maximum was 391 days. S. Newport was the predominant serotype, accounting for 51% of the cases. Age group and serotype were not significant predictors of Salmonella shedding duration in a Cox proportional hazards model, when stratifying by herd. However, the proportion of adult cows shedding for at least two consecutive monthly samples was significantly greater than the proportion of female calves shedding for this duration (Fisher's exact test p-value<0.01). Age group was also associated with mortality in this study; calves with salmonellosis were more likely to die than cows as estimated by a logistic regression model which controlled for herd as a random effect (p-value=0.04).

The incidence of salmonellosis among dairy herds in the northeastern United States.

The objectives of this study were to estimate the incidence of salmonellosis among a large sample of dairy herds in the northeastern United States (both at the animal level and the herd level), to describe the serotypes and antimicrobial resistance profiles of the positive samples, and to determine whether various herd-level factors were important predictors of incidence. Participating veterinarians enrolled 831 dairy herds and submitted fecal samples from 2,565 female dairy cattle for Salmonella culture because of suspicion of clinical disease. Estimates of animal-level incidence rates were calculated for each age group as the number of cases per animal time at risk, and an estimate of herd-level incidence rate was calculated as the number of positive herds per herd time at risk. Descriptive analysis of serotype data and level of antimicrobial resistance was performed, and Poisson regression analysis was used to study associations between the within-herd incidence of salmonellosis and certain predictor variables (herd size, housing type, vaccination status, and prior history of Salmonella infection). Salmonella was isolated from 576 (22.5%) samples representing 93 herds. The animal-level incidence rates for preweaned female calves, heifers, and adult cows were 8.1, 0.04, and 1.8 cases per 1,000 animal-years, respectively. The herd-level incidence rate was 8.6 positive herds per 100 herd-years. Salmonella Newport was the predominant serotype, accounting for 41% of the cases, followed by Salmonella Typhimurium. Over 68% of all isolates were resistant to 5 or more antimicrobial agents. Herd size was the only significant predictor of the incidence of salmonellosis in a multivariable model; herds with at least 400 female dairy cattle had a higher incidence rate than smaller herds. Our results shed light on the impact of salmonellosis on the dairy industry in the northeastern United States, and they help clarify the role of dairy cattle as a source of Salmonella serotypes that are also important human pathogens.

An active school model to promote physical activity in elementary schools: action schools! BC.

OBJECTIVE: To assess the impact of an active school model on children's physical activity (PA). DESIGN: 16-month cluster randomised controlled trial. SETTING: 10 elementary schools in Greater Vancouver, BC. PARTICIPANTS: 515 children aged 9-11 years. INTERVENTION: Action Schools! BC (AS! BC) is an active school model that provided schools with training and resources to increase children's PA. Schools implemented AS! BC with support from either external liaisons (liaison schools, LS; four schools) or internal champions (champion schools, CS; three schools). Outcomes were compared with usual practice (UP) schools (three schools). MAIN OUTCOME MEASUREMENTS: PA was measured four times during the study using pedometers (step count, steps/day). RESULTS: Boys in the LS group took 1175 more steps per day, on average, than boys in the UP group (95% CI: 97 to 2253). Boys in the CS group also tended to have a higher step count than boys in the UP group (+804 steps/day; 95% CI: -341 to 1949). There was no difference in girls' step counts across groups. CONCLUSIONS: The positive effect of the AS! BC model on boys' PA is important in light of the current global trend of decreased PA.

Promoting clinical scholarship through scholarly writing.

To promote clinical scholarship, critical thinking, problem-solving ability, and effective writing and research skills in their students, faculty replaced their major care plan with a capstone scholarly paper. The authors discuss how faculty, who serve as mentors, guide their students through the development of the scholarly paper.

Disease management program improves asthma outcomes.

OBJECTIVE: To show that a disease management program that empowers patients with asthma to participate in the management of their condition can improve quality of life and reduce the use of medical services. STUDY DESIGN: Utilization and quality-of-life data were tracked to identify outcome changes in patients with moderate to severe asthma. Baseline measures were used as a control and were compared with measures taken at 6 and 12 months after enrollment. PATIENTS AND METHODS: Study participants were from a single Medicaid managed care plan in western Pennsylvania. Patients' quality of life during their participation in the program was tracked through an outside pharmacoepidemiologic research firm. Utilization data were updated with every interaction between a patient and case management nurse. RESULTS: Both quality-of-life and utilization data show statistically significant improvements at 6 months. Further, 12-month data show improvement that is statistically significant in all measures with the exception of the adult quality-of-life measure, where a small sample size limited the statistical results. CONCLUSIONS: A collaborative, proactive approach to asthma management improves patients' quality of life and reduces use of costly medical services.

Identification of the major phosphorylation site of the hepatitis C virus H strain NS5A protein as serine 2321.

The hepatitis C virus (HCV) NS5A protein is phosphorylated by a cellular, serine/threonine kinase. To identify the major site(s) of NS5A phosphorylation, radiolabeled HCV-H NS5A phosphopeptides were purified and subjected to phosphoamino acid analysis and Edman degradation. These data identified the major intracellular phosphorylation site in the HCV-H NS5A protein as Ser(2321), a result verified by two additional, independent methods: (i) substitution of Ala for Ser(2321) and the concomitant disappearance of the major in vivo phosphorylated peptides and corresponding in vitro phosphorylated peptides; and (ii) comigration of the digestion products of a synthetic peptide phosphorylated on Ser(2321) with the major in vivo phosphorylated NS5A peptides. Site-directed mutagenesis of Ser(2321) suggested that phosphorylation of NS5A is dispensable for previously described interactions with NS4A and PKR, a cellular, antiviral kinase that does not appear to catalyze NS5A phosphorylation. The proline-rich nature of the amino acid sequence flanking Ser(2321) (PLPPPRS(2321) PPVPPPR) suggests that a proline-directed kinase is responsible for the majority of HCV NS5A phosphorylation, consistent with previous kinase inhibitor studies.

Combining isotopic and ecomorphological data to refine bovid paleodietary reconstruction: a case study from the Makapansgat Limeworks hominin locality.

The relationship between environmental change and hominin evolution remains obscure. For the most part, this stems from the difficulty of reconstructing ancient hominin habitats. Bovids are among the most frequently utilized paleoenvironmental indicators, but little is known about the habitat preferences of extinct taxa. It is generally assumed that fossil bovids both ate the same things and occupied the same habitats as their closest extant relatives. We test the first part of this assumption by reconstructing the diets of seven bovids from Makapansgat Limeworks, South Africa. Since diet and habitat are linked, these reconstructions have implications for our understanding of fossil bovid habitat tolerances. Ecomorphological and stable carbon isotope analyses are employed, allowing us to take advantage of the strengths and overcome the weaknesses of both. In most cases, fossil bovids did have similar diets to their extant relatives, and probably occupied similar habitats. Gazella vanhoepeni and Aepyceros sp., however, were almost exclusive browsers, and not mixed feeders like their living counterparts.

Cloning and assembly of complex libraries of full-length HCV cDNA clones.

Many studies of the molecular biology of hepatitis C virus (HCV) begin by obtaining representative cDNA clones of the viral genome. Most cloning strategies have been devised to deal with the low levels of HCV RNA present in starting material used for RNA isolation and cDNA synthesis. Typical sources include patient sera, liver samples, sera and tissues from infected chimpanzees, or in some cases, viral RNA obtained after replication in cell culture. Thus far, patient samples are the most common source of HCV RNA for cDNA cloning. Titers of HCV RNA in patient sera are low, typically ranging from 10(3) to 10(8) mol/mL. Except for a few instances, where cDNA libraries were obtained directly by isolating RNA from large volumes of high-titer sera (1,2), PCR is used for amplifying HCV cDNA prior to cloning. Since this procedure requires smaller amounts of HCV RNA, it is more generally useful for construction of complex cDNA libraries from a wide variety of HCV-containing samples.

Use of the vaccinia virus/t7 expression system for studying HCV protein processing.

HCV and related viruses are now classified as a separate genus in the family Flaviviridae (1), which includes two other genera, Flavivirus (2), and Pestivirus (3). The positive-strand HCV genome RNA is approx 9.4 kb in length and contains a highly conserved 5' noncoding region followed by a long open reading frame encoding a polyprotein of 3010-3033 amino acids (4,5) Recently, it was determined that the 3' end contains another highly conserved noncoding region approx 100 bp in length (6-8). Because a cell-culture system supporting efficient HCV replication is lacking, efforts to define potential HCV-encoded polypeptides have utilized expression of HCV cDNA in cell-free translation systems and in cell cultures. The HCV polyprotein appears to be cleaved at multiple sites to produce at least 10 structural and nonstructural (NS) proteins (9). The order and nomenclature of these cleavage products for the HCV-H strain are NH(2)-C-El-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B-COOH, where C, El, and E2 are putative structural proteins and the remaining NS proteins are believed to be replicase components (9-12). Host signal peptidase in the endoplasmatic reticulum lumen appears to catalyze cleavages in the structural-NS2 region (C/El, E1/E2, E2/p7, and p7/NS2 sites) (9,13), whereas an HCV-encoded serine proteinase located in the N-termmal one-third of the NS3 protein is responsible for four cleavages in the NS region (3/4A, 4A/4B, 4B/5A, and 5A/5B sites) (11,14-16).

Expression and Characterization of the HCV NS2 Protease.

Heterologous expression systems have been widely used to study hepatitis C virus (HCV) proteins in lieu of an efficient method for establishing HCV infections in cell culture. Studies of HCV polyprotein processing in both mammalian-cell-based and cell-free expression systems have shown that host signalase is responsible for cleavages between the structural proteins and at the N-terminus of NS2 (1-4), whereas a chymotrypsin-like serine protease located in the N-terminal region of NS3 is responsible for most cleavages between the nonstructural proteins, including the 3/4A, 4A/4B, 4B/5A, and 5A/5B sites (5-10). However, two observations indicated that the 2/3 site is cleaved by a distinct virus-encoded protease, known as the NS2, NS2-3, or Cpro-2 protease: (1) mutation of the catalytic serine at amino acid (aa) 1165 of NS3 abolished cleavage at all sites in the nonstructural polyprotein except the 2/3 site, and (2) two mutations in NS2 located more than 30 residues from the NS2-NS3 junction abolished cleavage at the 2/3 site, but had little or no effect on downstream cleavages catalyzed by the serine protease (8,11). The minimal region required for cleavage at the 2/3 site has been mapped to aa 898 on the N-terminal side (8) and aa 1207 on the C-terminal side (11) (numbers refer to HCV 1a and 1b isolates). Although a single construct extending from aa 898 to 1207 has never been tested for proteolytic viability, cleavage with an efficiency similar to that of polypeptides containing full-length NS2 and NS3 has been demonstrated for truncated constructs extending from aa 898 to 1233 or 827 to 1207 (8,11).

The NS5A/NS5 proteins of viruses from three genera of the family flaviviridae are phosphorylated by associated serine/threonine kinases.

Phosphorylation of the expressed NS5A protein of hepatitis C virus (HCV), a member of the Hepacivirus genus of the family Flaviviridae, has been demonstrated in mammalian cells and in a cell-free assay by an associated kinase activity. In this report, phosphorylation is also shown for the NS5A and NS5 proteins, respectively, of bovine viral diarrhea virus (BVDV) and yellow fever virus (YF), members of the other two established genera in this family. Phosphorylation of BVDV NS5A and YF NS5 was observed in infected cells, transient expression experiments, and a cell-free assay similar to the one developed for HCV NS5A. Phosphoamino acid analyses indicated that all three proteins were phosphorylated by serine/threonine kinases. Similarities in the properties of BVDV NS5A, YF NS5, and HCV NS5A phosphorylation in vitro further suggested that closely related kinases or the same kinase may phosphorylate these viral proteins. Conservation of this trait among three quite distantly related viruses representing three separate genera suggests that phosphorylation of the NS5A/NS5 proteins or their association with cellular kinases may play an important role in the flavivirus life cycle.

Molecular virology of hepatitis C virus: an update with respect to potential antiviral targets.

Hepatitis C virus (HCV), a positive-strand enveloped RNA virus, is a major cause of chronic liver disease worldwide. Cis-acting RNA elements and virus-encoded polypeptides required for HCV replication represent attractive targets for the development of antiviral therapies. Internal ribosome entry site-directed translation of HCV genome RNA produces a long polyprotein which is co- and post-translationally processed to yield at least 10 viral proteins. A host signal peptidase is responsible for maturation of the structural proteins located in the N-terminal one-third of the polyprotein. Thus far, four enzymatic activities encoded by the non-structural (NS) proteins have been reported. The NS2-3 region encodes an autoproteinase responsible for cleavage at the 2/3 site. The N-terminal one-third of NS3 functions as the catalytic subunit of a serine proteinase which cleaves at the 3/4A, 4A/4B, 4B/5A and 5A/5B sites, and NS4A is an essential cofactor for some of these cleavages. NS3 also encodes an RNA-stimulated NTPase/RNA helicase at its C terminus, and NS5B has been shown to possess an RNA-dependent RNA polymerase activity. To date, no functions have been reported for NS4B or NS5A in RNA replication, however, NS5A has been implicated in modulating the sensitivity of HCV to interferon. Sequence and structural conservation within the 3' terminal 98 bases of genomic RNA suggest a functional importance in the virus life-cycle and hence another target for antiviral intervention. Recently, HCV infection was shown to be initiated in chimpanzees following intrahepatic inoculation of RNA transcribed from cloned HCV cDNA. The ability to generate large quantities of infectious HCV RNA may facilitate the development of reliable cell culture replication systems useful for the evaluation of antiviral drugs.

Cloning of a Vibrio cholerae vibriobactin gene cluster: identification of genes required for early steps in siderophore biosynthesis.

Vibrio cholerae secretes the catechol siderophore vibriobactin in response to iron limitation. Vibriobactin is structurally similar to enterobactin, the siderophore produced by Escherichia coli, and both organisms produce 2,3-dihydroxybenzoic acid (DHBA) as an intermediate in siderophore biosynthesis. To isolate and characterize V. cholerae genes involved in vibriobactin biosynthesis, we constructed a genomic cosmid bank of V. cholerae DNA and isolated clones that complemented mutations in E. coli enterobactin biosynthesis genes. V. cholerae homologs of entA, entB, entC, entD, and entE were identified on overlapping cosmid clones. Our data indicate that the vibriobactin genes are clustered, like the E. coli enterobactin genes, but the organization of the genes within these clusters is different. In this paper, we present the organization and sequences of genes involved in the synthesis and activation of DHBA. In addition, a V. cholerae strain with a chromosomal mutation in vibA was constructed by marker exchange. This strain was unable to produce vibriobactin or DHBA, confirming that in V. cholerae VibA catalyzes an early step in vibriobactin biosynthesis.

Phosphorylation of the hepatitis C virus NS5A protein in vitro and in vivo: properties of the NS5A-associated kinase.

NS5A derived from a hepatitis C virus (HCV) genotype 1b isolate has previously been shown to undergo phosphorylation on serine residues (T. Kaneko, Y. Tanji, S. Satoh, M. Hijikata, S. Asabe, K. Kimura, and K. Shimotohno, Biochem. Biophys. Res. Commun. 205:320-326, 1994). In this report, phosphorylation of NS5A derived from HCV isolates of the 1a and distantly related 2a genotypes is demonstrated. Phosphoamino acid analysis of NS5A from the 1a isolate indicated that phosphorylation occurs predominantly on serine, with a minor fraction of threonine residues also being phosphorylated. NS5A phosphorylation was observed in diverse cell types, including COS-1, BHK-21, HeLa, and the hepatoma cell line HuH-7. Phosphorylation of a glutathione S-transferase (GST)/HCV-H NS5A fusion protein was also demonstrated in an in vitro kinase assay. This activity seemed to be highest when the pH of the reaction was neutral or slightly alkaline and displayed a preference for Mn2+ over Mg2+, with an optimum concentration of approximately 10 mM Mn2+. Somewhat surprisingly, in vitro phosphorylation of NS5A was inhibited by the addition of > or = 0.25 mM Ca2+ to reaction buffer containing Mn2+ and/or Mg2+. Comparison of phosphopeptide maps of NS5A phosphorylated in vitro and in cultured cells showed that most of the phosphopeptides comigrated, suggesting that one or more kinases involved in NS5A phosphorylation in vivo and in vitro are the same. The effects of various kinase inhibitors on NS5A phosphorylation were consistent with a kinase activity belonging to the CMGC group of serine-threonine kinases. The development of an in vitro kinase assay for NS5A phosphorylation should facilitate identification of kinase(s) responsible for its phosphorylation and of phosphorylation sites which may influence the function of NS5A in HCV propagation.

Early hominid evolution and ecological change through the African Plio-Pleistocene.

The habitats in which extinct hominids existed has been a key issue in addressing the origin and extinction of early hominids, as well as in understanding various morphological and behavioral adaptations. Many researchers postulated that early hominids lived in an open savanna (Dart, 1925; Robinson, 1963; Howell, 1978). However, Vrba (1985, 1988) has noted that a major global climatic and environmental shift from mesic, closed to xeric, open habitats occurred in the late African Pliocene (approximately 2.5 m.y.a.), thus implying that the earliest hominids existed in these mesic, wooded environs. This climatic shift is also suggested to have contributed to a pulse in speciation events with turnovers of many bovid and possibly hominid species. Previous environmental reconstructions of hominid localities have concentrated on taxonomic identities and taxonomic uniformitarianism to provide habitat reconstructions (e.g., Vrba, 1975; Shipman & Harris, 1988). In addition, relative abundances of species are often used to reconstruct a particular environment, when in fact taphonomic factors could be affecting the proportions of taxa. This study uses the morphological adaptations of mammalian assemblages found with early hominids to reconstruct the habitat based on each species' ecological adaptations, thus minimizing problems introduced by taxonomy and taphonomy. Research presented here compares east and south African Plio-Pleistocene mammalian fossil assemblages with 31 extant mammalian communities from eight different habitat types. All communities are analyzed through ecological diversity methods, that is, each species trophic and locomotor adaptations are used to reconstruct an ecological community and derive its vegetative habitat. Reconstructed habitats show that Australopithecus species existed in fairly wooded, well-watered regions. Paranthropus species lived in similar environs and also in more open regions, but always in habitats that include wetlands. Homo is the first hominid to exist in areas of fairly open, arid grassland. This change from closed to open habitats occurs gradually from about 4 m.y.a. until about 2 m.y.a. when there is a major increase in arid and grazing adapted mammals. Therefore, the appearance of open savannas do not appear to have influenced the origination or adaptations of the earliest hominids, but could have contributed to their demise. As Stanley (1992) hypothesized, Homo species appear the first to be adapted to open, arid environments.