The activity of a putative polyisoprenol-linked sugar translocase (Wzx) involved in Escherichia coli O antigen assembly is independent of the chemical structure of the O repeat

During O antigen lipopolysaccharide (LPS) synthesis in bacteria, transmembrane migration of undecaprenylpyrophosphate (Und-P-P)-bound O antigen subunits occurs before their polymerization and ligation to the rest of the LPS molecule. Despite the general nature of the translocation process, putative O-antigen translocases display a low level of amino acid sequence similarity. In this work, we investigated whether complete O antigen subunits are required for translocation. We demonstrate that a single sugar, GlcNAc, can be incorporated to LPS of Escherichia coli K-12. This incorporation required the functions of two O antigen synthesis genes, wecA (UDP-GlcNAc:Und-P GlcNAc-1-P transferase) and wzx (O-antigen translocase). Complementation experiments with putative O-antigen translocases from E. coli O7 and Salmonella enterica indicated that translocation of O antigen subunits is independent of the chemical structure of the saccharide moiety. Furthermore, complementation with putative translocases involved in synthesis of exopolysaccharides demonstrated that these proteins could not participate in O antigen assembly. Our data indicate that recognition of a complete Und-P-P-bound O antigen subunit is not required for translocation and suggest a model for O antigen synthesis involving recognition of Und-P-P-linked sugars by a putative complex made of Wzx translocase and other proteins involved in the processing of O antigen.

Genetic variation in MME in relation to neprilysin protein and enzyme activity, Aβ levels, and Alzheimer's disease risk

Neprilysin (NEP), also known as membrane metalloendopeptidase (MME), is considered amongst the most important ß-amyloid (Aß)-degrading enzymes with regard to prevention of Alzheimer's disease (AD) pathology. Variation in the NEP gene (MME) has been suggested as a risk factor for AD. We conducted a genetic association study of 7MME SNPs - rs1836914, rs989692, rs9827586, rs6797911, rs61760379, rs3736187, rs701109 - with respect to AD risk in a cohort of 1057 probable and confirmed AD cases and 424 age-matched non-demented controls from the United Kingdom, Italy and Sweden. We also examined the association of these MME SNPs with NEP protein level and enzyme activity, and on biochemical measures of Aß accumulation in frontal cortex - levels of total soluble Aß, oligomeric Aß(1-42), and guanidine-extractable (insoluble) Aß - in a sub-group of AD and control cases with post-mortem brain tissue. On multivariate logistic regression analysis one of the MME variants (rs6797911) was associated with AD risk (P = 0.00052, Odds Ratio (O.R. = 1.40, 95% confidence interval (1.16-1.70)). None of the SNPs had any association with Aß levels; however, rs9827586 was significantly associated with NEP protein level (p=0.014) and enzyme activity (p=0.006). Association was also found between rs701109 and NEP protein level (p=0.026) and a marginally non-significant association was found for rs989692 (p=0.055). These data suggest that MME variation may be associated with AD risk but we have not found evidence that this is mediated through modification of NEP protein level or activity.

Functional expression of KCNQ (Kv7) channels in guinea-pig bladder smooth muscle and their contribution to spontaneous activity

Background and Purpose: The aim of the study was to determine whether KCNQ channels are functionally expressed in bladder smooth muscle cells (SMC) and to investigate their physiological significance in bladder contractility. 

Experimental Approach: KCNQ channels were examined at the genetic, protein, cellular and tissue level in guinea pig bladder smooth muscle using RT-PCR, immunofluorescence, patch-clamp electrophysiology, calcium imaging, detrusor strip myography, and a panel of KCNQ activators and inhibitors. 

Key Results: KCNQ subtypes 1-5 are expressed in bladder detrusor smooth muscle. Detrusor strips typically displayed TTX-insensitive myogenic spontaneous contractions that were increased in amplitude by the KCNQ channel inhibitors XE991, linopirdine or chromanol 293B. Contractility was inhibited by the KCNQ channel activators flupirtine or meclofenamic acid (MFA). The frequency of Ca2+-oscillations in SMC contained within bladder tissue sheets was increased by XE991. Outward currents in dispersed bladder SMC, recorded under conditions where BK and KATP currents were minimal, were significantly reduced by XE991, linopirdine, or chromanol, and enhanced by flupirtine or MFA. XE991 depolarized the cell membrane and could evoke transient depolarizations in quiescent cells. Flupirtine (20M) hyperpolarized the cell membrane with a simultaneous cessation of any spontaneous electrical activity. 

Conclusions and Implications: These novel findings reveal the role of KCNQ currents in the regulation of the resting membrane potential of detrusor SMC and their important physiological function in the control of spontaneous contractility in the guinea pig bladder.

Chronic workplace stress and insufficient physical activity: a cohort study

Objectives To examine whether exposure to workplace stressors predicts changes in physical activity and the risk of insufficient physical activity.

Methods Prospective data from the Finnish Public Sector Study. Repeated exposure to low job control, high job demands, low effort, low rewards and compositions of these (job strain and effort-reward imbalance) were assessed at Time 1 (2000-2002) and Time 2 (2004). Insufficient physical activity (<14 metabolic equivalent task hours per week) was measured at Time 1 and Time 3 (2008). The effect of change in workplace stressors on change in physical activity was examined using fixed-effects (within-subject) logistic regression models (N=6665). In addition, logistic regression analysis was applied to examine the associations between repeated exposure to workplace stressors and insufficient physical activity (N=13 976). In these analyses, coworker assessed workplace stressor scores were used in addition to individual level scores.

Results The proportion of participants with insufficient physical activity was 24% at baseline and 26% at follow-up. 19% of the participants who were sufficiently active at baseline became insufficiently active at follow-up. In the fixed-effect analysis, an increase in workplace stress was weakly related to an increase in physical inactivity within an individual. In between-subjects analysis, employees with repeated exposure to low job control and low rewards were more likely to be insufficiently active at follow-up than those with no reports of these stressors; fully adjusted ORs ranged from 1.11 (95% CI 1.00 to 1.24) to 1.21 (95% CI 1.05 to 1.39).

Conclusions Workplace stress is associated with a slightly increased risk of physical inactivity.

Endocrine disruptor activity in bottled mineral and flavoured water

A panel of reporter gene assays (RGAs) coupled with a single solid phase extraction (SPE) step was developed and used to screen bottled mineral water for the presence of four classes of endocrine disruptors (EDs), oestrogens, androgens, progestagens and glucocorticoids.

Fourteen brands of bottled mineral water in triplicate (42 samples) were analysed. Overall, hormonal activity was found in 78% of the samples. Oestrogenic, androgenic, progestagenic and glucocorticoid activity was found in 38%, 38%, 36% and 55% of the samples, respectively at an average concentration of 10 ng/l 17 beta-estradiol equivalent (EEQ), 26 ng/l testosterone equivalent (TEQ), 123 ng/l progesterone equivalent (PEQ) and 13.5 ng/l hydrocortisone equivalent (HEQ).

The level of oestrogenic, androgenic and progestagenic activity observed is not considered a matter of concern for the consumers' health. It is unknown whether the glucocorticoid levels observed are safe. The ED source, long term exposure and mixture effects remain to be investigated. (C) 2012 Elsevier Ltd. All rights reserved.

Endocrine disrupting effects of ochratoxin A at the level of nuclear receptor activation and steroidogenesis

Ochratoxin A (OTA) is a mycotoxin and extrolite of fungi which has been reported in a range of foods. This study uses mammalian reporter gene assays (RGAs) with natural steroid receptors and the H295R steroidogenesis assay to assess the endocrine disrupting activity of OTA.

At the receptor level, OTA (within a concentration range of 0.25–2500 ng/ml) did not induce an agonistic response in an oestrogen, androgen, progestagen or glucocorticoid RGA. An antagonistic effect was observed in all of the RGAs at the highest concentration tested (2500 ng/ml). However, while there was no significant cytotoxic effect observed in the MTT (thiazolyl blue tetrazolium bromide) cell viability assay at this concentration, there was a corresponding change in cell morphology which may be related to the resulting antagonistic effect.

At the hormone production level, H295R cells were used as a steroidogenesis model and exposed to OTA (within a concentration range of 0.1–1000 ng/ml). Treatment of the cells with 1000 ng/ml OTA increased the production of estradiol (117 ± 14 ng/ml) over 3 times that of the solvent control (36 ± 9 pg/ml). Western blotting confirmed an increase in aromatase protein.

Overall the results indicate that OTA does not appear to interact with steroid receptors but has the potential to cause endocrine disruption by interfering with steroidogenesis. This is the first study identifying the effect OTA may have on production of the steroid hormone estradiol.

Multiple Regulatory Pathways Associated with High-Level Ciprofloxacin and Multidrug Resistance in Salmonella enterica Serovar Enteritidis: Involvement of ramA and Other Global Regulators

Mechanisms of antibiotic resistance were examined in nalidixic acid-resistant Salmonella enterica serovar Enteritidis field isolates displaying decreased susceptibility to ciprofloxacin and in in vitro-derived ciprofloxacin-resistant mutants (104-cip and 5408-cip). All field isolates harbored a single gyrA mutation (D87Y). Deletion of acrB and complementation with wild-type gyrA increased quinolone susceptibility. Selection for ciprofloxacin resistance was associated with the development of an additional gyrA (S83F) mutation in 104-cip, novel gyrB (E466D) and parE (V461G) mutations in 5408-cip, overexpression of acrB and decreased susceptibility to nonquinolone antibiotics in both mutants, and decreased OmpF production and altered lipopoly- saccharide in 104-cip. Complementation of mutated gyrA and gyrB with wild-type alleles restored susceptibility to quinolones in 104-cip and significantly decreased the ciprofloxacin MIC in 5408-cip. Complementation of parE had no effect on quinolone MICs. Deletion of acrB restored susceptibility to ciprofloxacin and other antibiotics tested. Both soxS and marA were overexpressed in 104-cip, and ramA was overexpressed in 5408-cip. Inactivation of each of these global regulators lowered ciprofloxacin MICs, decreased expression of acrB, and restored susceptibility to other antibiotics. Mutations were found in soxR (R20H) and in soxS (E52K) in 104-cip and in ramR (G25A) in 5408-cip. In conclusion, both efflux activity and a single gyrA mutation contribute to nalidixic acid resistance and reduced ciprofloxacin sensitivity. Ciprofloxacin resistance and decreased susceptibility to multiple antibiotics can result from different genetic events leading to development of target gene mutations, increased efflux activity resulting from differential expression of global regulators associated with mutations in their regulatory genes, and possible altered membrane permeability.

Physical activity and the rejuvenation of Connswater (PARC study): protocol for a natural experiment investigating the impact of urban regeneration on public health

Background: There is a dearth of evidence regarding the impact of urban regeneration projects on public health, particularly the nature and degree to which urban regeneration impacts upon health-related behaviour change. Natural experiment methodology enables comprehensive large-scale evaluations of such interventions. The Connswater Community Greenway in Belfast is a major urban regeneration project involving the development of a 9 km linear park, including the provision of new cycle paths and walkways. In addition to the environmental improvements, this complex intervention involves a number of programmes to promote physical activity in the regenerated area. The project affords a unique opportunity to investigate the public health impact of urban regeneration.

Methods/Design: The evaluation framework was informed by the socio-ecological model and guided by the RE-AIM Framework. Key components include: (1) a quasi-experimental before-and-after survey of the Greenway population (repeated cross-sectional design), in tandem with data from a parallel Northern Ireland-wide survey for comparison; (2) an assessment of changes in the local built environment and of walkability using geographic information systems; (3) semi-structured interviews with a purposive sample of survey respondents, and a range of community stakeholders, before and after the regeneration project; and (4) a cost-effectiveness analysis. The primary outcome is change in proportion of individuals identified as being regularly physically active, according to the current UK recommendations. The RE-AIM Framework will be used to make an overall assessment of the impact of the Greenway on the physical activity behaviour of local residents.

Discussion: The Connswater Community Greenway provides a significant opportunity to achieve long-term, population level behaviour change. We argue that urban regeneration may be conceptualised meaningfully as a complex intervention comprising multiple components with the potential, individually and interactively, to affect the behaviour of a diverse population. The development and implementation of our comprehensive evaluation framework reflects this complexity and illuminates an approach to the empirical, rigorous evaluation of urban regeneration. More specifically, this study will add to the much needed evidence-base about the impact of urban regeneration on public health as well as having important implications for the development of natural experiment methodology.

Serum erythropoietic activity in acute anemia--an animal model

Serum erythropoietic activity and reticulocyte response to anemia were investigated using a rabbit model. In hemolytic anemia, induced by injections of phenylhydrazine on Day 0 the hemoglobin reached a nadir (mean, 6.23 g/dl) on Day 4 when SEA was maximal (mean, 765 mU/ml). In animals venesected on Day 0 and Day 1 to produce anemia of equal severity, the SEA was maximal (mean 235 mU/ml) on Day 2. In both groups the reticulocyte response peaked on Day 7--at 34% for the hemolytic group and 21% for the venesected group. The 2,3-diphosphoglycerate, measured on Day 4, was significantly reduced in the PHZ-treated group. In the venesected group the 2,3-DPG increased between Day 0 and Day 4. There were no concurrent changes in acid-base balance. These results imply that the degree of anemia is only one of the factors which influence the level of circulating SEA.

Physical Activity and Cognitive Function in the Elderly: a Systematic Review

Background: Physical activity appears important contributor for healthy aging, including cognitive function. However, it is unclear whether late life physical activity alone is beneficial to cognitive function. We performed a systematic review to examine the effect of late life physical activity in maintaining cognitive function in older persons.
Methods: Search Strategy and Selection criteria: The search sources consisted of PubMed, MEDLINE, CINAHL, Cochrane Controlled Trials Register (CENTRAL), and the University of Washington Medical School Library Database between July 15, 2011 and August 15, 2012 with language restricted to English. Studies that were published in journals on or after January 2000 with participants older than 60 years of age were reviewed. Randomized controlled trials including at least 30 participants and lasting for at least 6 months and all observational studies of at least 100 participants and lasting at least 1 year in duration were eligible for inclusion Two reviewers assessed the applicability and results of these studies.
Results: Twenty-six studies fulfilling the inclusion criteria are included. Twenty-one studies reported that late life physical activity resulted in maintenance or enhancement of cognitive function. Three studies reported a dose-response relationship between physical activity and cognition.
Conclusions: Late life physical activity is beneficial for cognitive function in the elderly. However, the majority of the evidence is of medium quality with moderate risk of bias. Larger, randomized controlled trials are needed to better define the association between late life physical activity and cognitive function. Further research is required to determine which types of exercise have the greatest benefits on specific cognitive domains. Despite these caveats, current data are sufficient to recommend that moderate level, late life physical activity may be an effective method to improve cognitive function and delay the onset and progression of cognitive disease in the elderly.

Knowledge of UK physical activity guidelines:Implications for better targeted health promotion

Objective. The aim of this study is to investigate the correlates of knowledge of the UK physical activity (PA) guidelines.

Method. A Northern Ireland-wide population survey (2010/2011) of 4653 adults provided cross-sectional data on PA, knowledge of guidelines and socio demographic characteristics. Multinomial logistic regression was used to investigate the associations between knowledge and socio-demographic characteristics (Model 1); and modifiable health behaviours (Model 2).

Results. Results showed that 47% of respondents were unaware of PA guidelines. Males who had a lower level of education (OR 5.91; 95% CI 1.67, 20.94), lived in more deprived areas (OR 4.80; 95% CI 1.87, 12.30), low income (OR 2.36; 95% CI 1.63, 3.41) and did no PA (OR 2.74; 95% CI 1.31, 5.76) were more likely to be unaware of the guidelines. Females who were younger (OR 1.03; 95% CI 1.02, 1.05) and reported poor health (OR 2.71; 95% CI 1.61, 4.58) were more likely to be unaware of the guidelines.

Conclusion. There is a lack of awareness about the levels of PA needed to promote health. An understanding of the characteristics of those who are unaware of the guidelines has important implications for the design of targeted, effective health promotion.

Physical Activity, Gender, Weight Status, and Wellbeing in 9- to 11-Year-Old Children: A Cross-Sectional Survey

Background: The aim of this study was to examine the relationship between physical activity and wellbeing in children, and to further explore the extent to which this may vary by gender and weight status. Method: A representative sample of 1424 9- to 11-year-olds completed a self-report measure of physical activity, the Child Health and Illness Profile, KIDSCREEN, and a self-esteem scale. Body Mass Index (BMI) measurements were also obtained. Results: 24% of children achieved the recommended level of 60 minutes of moderate-tovigorous intensity physical activity (MVPA) per day, with more boys than girls achieving this level. Children achieving the recommended level of MVPA scored significantly higher on measures of the Child Health and Illness Profile (F(5, 1354) = 5.03; P < .001), KIDSCREEN (F(3, 1298) = 4.68; P = .003), and self-esteem (F(1,1271) = 18.73; P = .003) than less active children although the effect sizes were small (ηp2 ≈ .01). Substantial gender differences in wellbeing were found reflecting gender specific behaviors and socialization. Weight status had negligible influence on wellbeing. Conclusions: Children who meet the recommended guidelines of MVPA were more likely to have better wellbeing. When attempting to raise children’s physical activity levels consideration should be given to the specific relationships between wellbeing and physical activity.

Individual Characteristics Associated with Mismatches between Self-Reported and Accelerometer-Measured Physical Activity

Background: Accurate assessment tools are required for the surveillance of physical activity (PA) levels and the assessment of the effect of interventions. In addition, increasing awareness of PA is often used as the first step in pragmatic behavioural interventions, as discrepancies between the amount of activity an individual perceives they do and the amount actually undertaken may act as a barrier to change. Previous research has demonstrated differences in the amount of activity individuals report doing, compared to their level of physical activity when measured with an accelerometer. Understanding the characteristics of those whose PA level is ranked differently when measured with either self-report or accelerometry is important as it may inform the choice of instrument for future research. The aim of this project was to determine which individual characteristics are associated with differences between self-reported and accelerometer measured physical activity.

Methods: Participant data from the 2009 wave of the Commuting and Health in Cambridge study were used. Quartiles of self-reported and accelerometer measured PA were derived by ranking each measure from lowest to highest. These quartiles were compared to determine whether individuals’ physical activity was ranked higher by either method. Multinomial logistic regression models were used to investigate the individual characteristics associated with different categories of mismatch.

Results: Data from 486 participants (70% female) were included in the analysis. In adjusted analyses, the physical activity of overweight or obese individuals was significantly more likely to be ranked higher by self-report than by accelerometer than that of normal-weight individuals (OR = 2.07, 95%CI = 1.28–3.34), particularly among women (OR = 3.97, 95%CI = 2.11–7.47).

Conclusions: There was a greater likelihood of mismatch between self-reported and accelerometer measured physical activity levels in overweight or obese adults. Future studies in overweight or obese adults should consider employing both methods of measurement.

Search for the Return of Activity in Active Asteroid 176P/LINEAR

We present the results of a search for the reactivation of active asteroid 176P/LINEAR during its 2011 perihelion passage using deep optical observations obtained before, during, and after that perihelion passage. Deep composite images of 176P constructed from data obtained between 2011 June and 2011 December show no visible signs of activity, while photometric measurements of the object during this period also show no significant brightness enhancements similar to that observed for 176P between 2005 November and 2005 December when it was previously observed to be active. An azimuthal search for dust emission likewise reveals no evidence for directed emission (i.e., a tail, as was previously observed for 176P), while a one-dimensional surface brightness profile analysis shows no indication of a spherically symmetric coma at any time in 2011. We conclude that 176P did not in fact exhibit activity in 2011, at least not on the level on which it exhibited activity in 2005, and suggest that this could be due to the devolatization or mantling of the active site responsible for its activity in 2005.

Trading Activity in Options and Stock Around Price-Sensitive News Announcements

This study investigates the trading activity in options and stock markets around informed events with extreme daily stock price movements. We find that informed agents are more likely to trade options prior to negative news and stocks ahead of positive news. We also show that optioned stocks overreact to the arrival of negative news, but react efficiently to positive news. However, the overreaction patterns are unique to the subsample of stocks with the lowest pre-event abnormal option/stock volume ratio (O/S). This finding suggests that the incremental benefit of option listing is related to the level of option trading activity, over and beyond the presence of an options market on the firm's stock. Finally, we find that the pre-event abnormal O/S is a better predictor of stock price patterns following a negative shock than is the pre-event O/S, implying that the former may contain more information about the future value of stocks than the latter.