Thermoneutral Temperature Exposure Enhances Slow Wave Sleep with a Correlated Improvement in Amyloid Pathology in a Triple-Transgenic Mouse Model of Alzheimer's Disease

Accumulation of amyloid-β (Aβ) plays an important role in Alzheimer's disease (AD) pathology. There is growing evidence that disordered sleep may accelerate AD pathology by impeding the physiological clearance of Aβ from the brain that occurs in normal sleep. Therapeutic strategies for improving sleep quality may therefore help slow disease progression. It is well documented that the composition and dynamics of sleep are sensitive to ambient temperature. We therefore compared Aβ pathology and sleep metrics derived from polysomnography in 12-month-old female 3xTg-AD mice (n = 8) exposed to thermoneutral temperatures during the light period over four weeks to those of age- and sex-matched controls (n = 8) that remained at normal housing temperature (22⁰C) during the same period. The treated group experienced greater proportions of slow wave sleep (SWS)-i.e., epochs of elevated 0.5-2 Hz slow wave activity during non-rapid eye movement (NREM) sleep-compared to controls. Assays performed on mouse brain tissue harvested at the end of the experiment showed that exposure to thermoneutral temperatures significantly reduced levels of DEA-soluble (but not RIPA- or FA-soluble) Aβ40 and Aβ42 in the hippocampus, though not in the cortex. With both groups pooled together and without regard to treatment condition, NREM sleep continuity and any measure of SWS within NREM at the end of the treatment period were inversely correlated with DEA-soluble Aβ40 and Aβ42 levels, again in the hippocampus but not in the cortex. These findings suggest that experimental manipulation of SWS could offer useful clues into the mechanisms and treatment of AD.

BMI is dead; long live waist-circumference indices: But which index should we choose to predict cardio-metabolic risk?

BACKGROUND AND AIMS

There is growing evidence that Body Mass Index (BMI) is unfit for purpose. Waist circumference (WC) indices appear to be the preferred alternative, although it is not clear which WC index is optimal at predicting cardio-metabolic risk (CMR) and associated health outcomes.

METHODS AND RESULTS

We obtained a stratified random probability sample of 53,390 participants from the Health Survey for England (HSE), 2008-2018. The four available CMR factors were; high-density lipoproteins (HDL) cholesterol, glycated haemoglobin (HbA1c), systolic (SBP) and diastolic blood pressure (DBP). Strength of association between the four cardio-metabolic risk factors and competing anthropometric indicators of weight status [BMI, Waist-to-height ratio (WHTR), unadjusted WC, and a new WC index independent of height, WHT·5R = WC/height^0.5] was assessed separately, using simple correlations and ANCOVAs, and together (combined) using MANCOVA, controlling for age, sex and ethnicity. Centile curves for the new index WHT·5R = WC/height^0.5were also provided.

CONCLUSIONS

Waist-circumference indices were superior to BMI when explaining/predicting our CMR factors, before and after controlling for age, sex and ethnicity. No single WC index was consistently superior. Results suggest that WHTR is the strongest predictor of HbA1c, confirming that shorter individuals are at great risk of diabetes. The most appropriate WC index associated with blood pressure was WHT·5R for DBP, or unadjusted WC for SBP. Given HDL cholesterol is independent of height, the best predictor of HDL was WHT.5R. Clearly, "no one size fits all!". MANCOVA identified WHT·5R to be the best single WC index associated with a composite of all four CMR factors.

UK university staff experience high levels of sedentary behaviour during work and leisure time

Objective. Reducing sedentary behaviours at work is imperative. Before effective strategies can be developed there is a need to understand profiles of activity within particular roles and organizations. This study aimed to determine activity profiles of staff by job title at a UK university. Methods. Three-hundred and seventeen participants completed the international physical activity questionnaire - short form to determine physical activity profiles. Fifty-one participants also wore a wrist-worn GENEActiv accelerometer for 7 days and completed a self-report diary denoting work and leisure hours. Results. Twenty-one per cent of respondents were categorized as inactive and achieved 298 ± 178 metabolic equivalent minutes (MET-min)/week. Those in administrative roles were most sedentary (501 ± 161 min/day). Accelerometer data highlighted that sedentary time was identical between job roles (pooled mean 8746 ± 823 counts) and equated to 84 ± 9% of total time. During working hours, management, professional and specialist job roles had the highest level of sedentary time (2066 ± 416 counts). Conclusion. Time spent undertaking sedentary activities during working hours contributes to reduced overall activity and can impede productivity, performance and health. Interventions encouraging regular movement and preventing sedentary behaviours at work are therefore required.

Objectively measured waist circumference is most strongly associated in father-boy and mother-girl dyads in a large nationally representative sample of New Zealanders

BACKGROUND

The prevalence of children with elevated weight or obesity is concerning for public health due to associated comorbidities. This study investigates associations between parental adiposity, physical activity (PA), fruit and vegetable consumption, and child adiposity and moderation by both child and parent gender.

METHODS

Cross-sectional nationally representative data from the New Zealand Health Survey were pooled for the years 2013/14-2016/17. Parent and child surveys were matched resulting in 13,039 child (2-14 years) and parent (15-70 years) dyads. Parent and child, height (cm), weight (kg) and waist circumference (WC) were measured objectively. Height and weight were used to calculate BMI. Linear regression, accounting for clustered samples (b [95% CI]) investigated associations between parental characteristics and child BMI z-score and WC. Interactions and stratification were used to investigate effect moderation by parent gender, child gender, and parent adiposity.

RESULTS

Parental PA and fruit and vegetable consumption were unrelated to child adiposity. Overall, higher parent BMI was related to a higher child BMI z-score (b = 0.047 [0.042, 0.052]) and higher parental WC was related to a higher child WC (0.15 [0.12, 0.17]). A three-way interaction revealed no moderation by parent gender, child gender, and parent BMI for child BMI z-score ((b = 0.005 [-0.017, 0.027], p = 0.318). However, a three-way interaction revealed moderation by parent gender, child gender, and parent WC for child WC (b = 0.13 [0.05, 0.22]). The slightly stronger associations were seen between father-son WC (b = 0.20 [0.15, 0.24]) and mother-daughter WC (b = 0.19 [0.15, 0.22]).

CONCLUSIONS

The findings are highly relevant for those wishing to understand the complex relationships between child-parent obesity factors. Findings suggest that family environments should be a key target for obesity intervention efforts and show how future public health interventions should be differentiated to account for both maternal and paternal influences on child adiposity.

The influence of sleep health on dietary intake: a systematic review and meta-analysis of intervention studies

BACKGROUND

Poor dietary intake increases disease risk, and poor sleep influences diet. This systematic review and meta-analysis of intervention studies aimed to evaluate the effect of sleep health on dietary intake in adults.

METHODS

Five online databases were used to identify studies published between 1970 and 2019. Included studies were interventions that modified sleep and reported dietary outcomes.

RESULTS

Fifty four full texts were assessed and 24 publications were included. Following risk of bias appraisal, data were narratively summarised and a sub-group of studies (n = 15) was meta-analysed to determine the effect of sleep on dietary intake. One intervention modified sleep timing and 23 modified duration. Sleep duration was partially restricted (≤5.5 h night^-1 ) (n = 16), totally restricted (n = 4), partially and totally restricted (n = 1), and extended (n = 2). Dietary outcomes were energy intake (n = 24), carbohydrate, fat, protein intake (n = 20), single nutrient intake (n = 5), diet quality (n = 1) and food types (n = 1). Meta-analysis indicated partial sleep restriction results in higher energy intake in intervention compared with control [standardised mean difference (SMD) = 0.37; 95% confidence interval (CI) = 0.21-0.52; P < 0.001], with a mean difference of 204 kcal (95% CI = 112-295; P < 0.001) in daily energy intake, and a higher percentage of energy from fat, protein, carbohydrate (fat: SMD = 0.33; 95% CI = 0.16-0.51; P < 0.001; protein: SMD = 0.30, 95% CI = 0.12-0.47, P = 0.001; carbohydrate: SMD = 0.22, 95% CI = 0.04-0.39, P = 0.014).

CONCLUSIONS

Partial sleep restriction with duration of ≤5.5 h day^-1 increases daily energy intake, as well as fat, protein and carbohydrate intake. Further research is needed to determine the relationship between other dimensions of sleep health and dietary intake.

Can you elaborate on that? Addressing participants' need for cognition in computer-tailored health behavior interventions

Computer-tailored interventions, which deliver health messages adjusted based on characteristics of the message recipient, can effectively improve a range of health behaviours. Typically, the content of the message is tailored to user demographics, health behaviours and social cognitive factors (e.g., intentions, attitudes, self-efficacy, perceived social support) to increase message relevance, and thus the extent to which the message is read, considered and translated into attitude and behaviour change. Some researchers have suggested that the efficacy of computer-tailored interventions may be further enhanced by adapting messages to suit recipients' need for cognition (NFC) - a personality trait describing how individuals tend to process information. However, the likely impact of doing so, especially when tailored in conjunction with other variables, requires further consideration. It is possible that intervention effects may be reduced in some circumstances due to interactions with other variables (e.g., perceived relevance) that also influence information processing. From a practical point of view, it is also necessary to consider how to optimally operationalise and measure NFC if it is to be a useful tailoring variable. This paper aims to facilitate further research in this area by critically examining these issues based on relevant theories and existing evidence.

Activity of Streptococcus mutans VicR Is Modulated by Antisense RNA

The VicRK 2-component system of Streptococcus mutans regulates genes associated with cell wall biogenesis and biofilm formation. A putative RNase III-encoding gene ( rnc) is located downstream from the vicRKX operon. The goals of this study were to investigate the potential role of VicR in the regulation of adjacent downstream genes and evaluate transcription levels of vicR during planktonic and biofilm growth. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to investigate whether vicRKX and adjacent downstream genes were cotranscribed. Binding of purified recombinant VicR protein to promoter regions of vicR, rnc, and syfA genes was confirmed by electrophoretic mobility shift assay and by chromatin immunoprecipitation analyses. VicR antisense (AS vicR) RNA was detected by Northern blotting and qRT-PCR assays. AS vicR overexpression mutants were constructed, and the biofilm biomass was determined by crystal violet microtiter assay. Adjacent downstream genes rnc, smc, syfA, smu.1511, and syfB were cotranscribed with vicRKX. The predicted promoter regions of vicR, rnc, and syfA genes were directly regulated by VicR. An AS vicR RNA transcript was detected upstream of the rnc gene. Expression of the AS vicR RNA transcript was elevated in planktonic cultures and repressed during biofilm growth. In addition, Western blot data showed that expression of the VicR protein decreased by 35% in planktonic as compared with biofilm cultures. Furthermore, we show that overexpression of AS vicR led to a reduction in biofilm formation. The downstream genes rnc, smc, syfA, smu.1511, and syfB are cotranscribed with vicRKX. VicR is autophosphorylated, and rnc and syfA are directly regulated by VicR. Expression of VicR protein correlated inversely with different levels of AS vicR RNA transcript and growth conditions. The biofilm biomass decreased in the AS vicR overexpression mutant. These data suggest a role for the AS vicR RNA transcript in posttranscriptional regulation of VicR protein production in S. mutans.

Clusters of health behaviours in Queensland adults are associated with different socio-demographic characteristics

Background

The co-occurrence of unhealthy lifestyles, calls for interventions that target multiple health behaviours. This study investigates the clustering of health behaviours and examines demographic differences between each cluster.

Methods

In total, 934 adults from Queensland, Australia completed a cross-sectional survey assessing multiple health behaviours. A two-step hierarchical cluster analysis using multiple iterations identified the optimal number of clusters and the subset of distinguishing health behaviour variables. Univariate analyses of variance and chi-squared tests assessed difference in health behaviours by socio-demographic factors and clusters.

Results

Three clusters were identified: the ‘lower risk’ cluster (n = 436) reported the healthiest profile and met all public health guidelines. The ‘elevated risk’ cluster (n = 105) reported a range of unhealthy behaviours such as excessive alcohol consumption, sitting time, fast-food consumption, smoking, inactivity and a lack of fruit and vegetables. The ‘moderate risk behaviour’ cluster (n = 393) demonstrated some unhealthy behaviours with low physical activity levels and poor dietary outcomes. The ‘elevated risk’ cluster were significantly younger and more socio-economically disadvantaged than both the ‘lower and moderate risk’ clusters.

Discussion

Younger people who live in more deprived areas were largely within the ‘elevated risk’ cluster and represent an important population for MHBC interventions given their wide range of unhealthy behaviours.

Effects of external loads on postural sway during quiet stance in adults aged 20-80 years

The purpose of this study was to investigate the effects of holding external loads on postural sway during upright stance across age decades. Sixty-five healthy adults (females, n = 35), aged 18-80 years were assessed in four conditions; (1) standing without holding a load, holding a load corresponding to 5% body mass in the (2) left hand, (3) right hand and (4) both hands. The centre of pressure (COP) path length and anteroposterior and mediolateral COP displacement were used to indirectly assess postural sway. External loading elicited reductions in COP measures of postural sway in older age groups only (P < 0.05). No changes were observed in younger or intermediate aged adults (P > 0.05). Holding external loads during standing is relevant to many activities of daily living (i.e. holding groceries). The reduction in postural sway may suggest this type of loading has a stabilising effect during quiet standing among older adults.

Designing more engaging computer-tailored physical activity behaviour change interventions for breast cancer survivors: lessons from the iMove More for Life study

BACKGROUND

Participating in regular physical activity is a recommended cancer recovery strategy for breast cancer survivors. However, tailored support services are not widely available and most survivors are insufficiently active to obtain health benefits. Delivering tailored programs via the Internet offers one promising approach. However, recent evaluations of such programs suggest that major improvements are needed to ensure programs meet the needs of users and are delivered in an engaging way. Understanding participants' experiences with current programs can help to inform the next generation of systems.

PURPOSE

The purposes of this study are to explore breast cancer survivor's perspectives of and experiences using a novel computer-tailored intervention and to describe recommendations for future iterations.

METHODS

Qualitative data from a sub-sample of iMove More for Life study participants were analysed thematically to identify key themes. Participants long-term goals for participating in the program were explored by analysing open-ended data extracted from action plans completed during the intervention (n = 370). Participants negative and positive perceptions of the website and recommendations for improvement were explored using data extracted from open-ended survey items collected at the immediate intervention follow-up (n = 156).

RESULTS

The majority of participants reported multi-faceted goals, consisting of two or more outcomes they hoped to achieve within a year. While clear themes were identified (e.g. 'being satisfied with body weight'), there was considerable variability in the scope of the goal (e.g. desired weight loss ranged from 2 to 30 kg). Participants' perceptions of the website were mixed, but clear indications were provided of how intervention content and structure could be improved.

CONCLUSIONS

This study provides insight into how to better accommodate breast cancer survivors in the future and ultimately design more engaging computer-tailored interventions.

Is the Ergogenicity of Caffeine Affected by Increasing Age? The Direct Effect of a Physiological Concentration of Caffeine on the Power Output of Maximally Stimulated EDL and Diaphragm Muscle Isolated from the Mouse

INTRODUCTION

Caffeine is a well-established performance enhancing nutritional supplement in a young healthy population, however far less is known about how its ergogenicity is affected by increasing age. A recent review has highlighted the value of studies examining the direct effect of caffeine on isolated skeletal muscle contractility, but the present work is the first to assess the direct effect of 70µM caffeine (physiological maximum) on the maximal power output of isolated mammalian muscle from an age range representing developmental to early ageing.

METHOD

Female CD1 mice were aged to 3, 10, 30 and 50 weeks (n = 20 in each case) and either whole EDL or a section of the diaphragm was isolated and maximal power output determined using the work loop technique. Once contractile performance was maximised, each muscle preparation was treated with 70µM caffeine and its contractile performance was measured for a further 60 minutes.

RESULTS

In both mouse EDL and diaphragm 70µM caffeine treatment resulted in a significant increase in maximal muscle power output that was greatest at 10 or 30 weeks (up to 5% and 6% improvement respectively). This potentiation of maximal muscle power output was significantly lower at the early ageing time point, 50 weeks (up to 3% and 2% improvement respectively), and in mice in the developmental stage, at 3 weeks of age (up to 1% and 2% improvement respectively).

CONCLUSION

Uniquely, the present findings indicate a reduced age specific sensitivity to the performance enhancing effect of caffeine in developmental and aged mice which is likely to be attributed to age related muscle growth and degradation, respectively. Importantly, the findings indicate that caffeine may still provide a substantial ergogenic aid in older populations which could prove important for improving functional capacity in tasks of daily living.

Restricting feeding to the active phase in middle-aged mice attenuates adverse metabolic effects of a high-fat diet

Time-restricted feeding ameliorates the deleterious effects of a high-fat diet on body weight and metabolism in young adult mice. Because obesity is highly prevalent in the middle-aged population, this study tested the hypothesis that time-restricted feeding alleviates the adverse effects of a high-fat diet in male middle-aged (12months) mice. C57BL6/J mice were fed one of three diets for 21-25weeks: 1) high-fat diet (60% total calories from fat) ad-libitum (HFD-AL), 2) HFD, time-restricted feeding (HFD-TRF), and 3) low-fat diet (10% total calories from fat) ad-libitum (LFD-AL) (n=15 each). HFD-TRF mice only had food access for 8h/day during their active period. HFD-TRF mice gained significantly less weight than HFD-AL mice (~20% vs 55% of initial weight, respectively). Caloric intake differed between these groups only during the first 8weeks and accounted for most but not all of their body weight difference during this time. TRF of a HFD lowered glucose tolerance in terms of incremental area under the curve (iAUC) (p<0.02) to that of LFD-AL mice. TRF of a HFD lowered liver weight (p<0.0001), but not retroperitoneal or epididymal fat pad weight, to that of LFD-AL mice. Neither HFD-AL nor HFD-TRF had any effect on performance in the novel object recognition or object location memory tests. Circulating corticosterone levels either before or after restraint stress were not affected by diet. In conclusion, TRF without caloric restriction is an effective strategy in middle-aged mice for alleviating the negative effects of a HFD on body weight, liver weight, and glucose tolerance.

TaylorActive--Examining the effectiveness of web-based personally-tailored videos to increase physical activity: a randomised controlled trial protocol

BACKGROUND

Physical inactivity levels are unacceptably high and effective interventions that can increase physical activity in large populations at low cost are urgently needed. Web-based interventions that use computer-tailoring have shown to be effective, though people tend to 'skim' and 'scan' text on the Internet rather than thoroughly read it. The use of online videos is, however, popular and engaging. Therefore, the aim of this 3-group randomised controlled trial is to examine whether a web-based physical activity intervention that provides personally-tailored videos is more effective when compared with traditional personally-tailored text-based intervention and a control group.

METHODS/DESIGN

In total 510 Australians will be recruited through social media advertisements, e-mail and third party databases. Participants will be randomised to one of three groups: text-tailored, video-tailored, or control. All groups will gain access to the same web-based platform and a library containing brief physical activity articles. The text-tailored group will additionally have access to 8 sessions of personalised physical activity advice that is instantaneously generated based on responses to brief online surveys. The theory-based advice will be provided over a period of 3 months and address constructs such as self-efficacy, motivation, goal setting, intentions, social support, attitudes, barriers, outcome expectancies, relapse prevention and feedback on performance. Text-tailored participants will also be able to complete 7 action plans to help them plan what, when, where, who with, and how they will become more active. Participants in the video-tailored group will gain access to the same intervention content as those in the text-tailored group, however all sessions will be provided as personalised videos rather than text on a webpage. The control group will only gain access to the library with generic physical activity articles. The primary outcome is objectively measured physical activity. Secondary outcomes include website engagement and retention, quality of life, depression, anxiety, stress, sitting time, sleep and psychosocial correlates of physical activity. Outcomes will be measured at baseline, 3, and 9 months.

DISCUSSION

This study presents an ideal opportunity to study the effectiveness of an isolated feature within a web-based physical activity intervention and the knowledge generated from this study will help to increase intervention effectiveness.

TRIAL REGISTRATION

Australian New-Zealand Clinical Trial Registry: ACTRN12615000057583 . Registered 22 January 2015. CQUniversity Ethics Project Number: H14/07-163.

An integrated curriculum approach to increasing habitual physical activity in deprived South Asian children

Integrating physical activity (PA) within a school curriculum is a promising approach for increasing PA in children. To date, no research has examined its effectiveness in increasing the low levels of PA witnessed in deprived South Asian (SA) children. The study aims to ascertain whether an integrated school-based curriculum and pedometer intervention could increase PA in children from deprived SA backgrounds. Following ethical approval and informed consent, 134 deprived SA children (63 boys, 71 girls, control (n = 40, mean age = 11.12 years, SD = 0.32 years) and intervention (n = 94, mean age = 9.48 years, SD = 0.62 years)) from a primary school in England, UK, completed a 6-week integrated PA intervention based on virtually walking from their school (middle of the country) to the coast and back (March-July 2013). Habitual PA was determined at baseline and post 6 weeks intervention for both groups, and determined weekly during the intervention in the experimental group. The results indicated that average daily steps were significantly higher at post 6 weeks compared to baseline for the intervention group (intervention mean change = 8694 steps/day, SD = 7428 steps/day vs. control mean change = -1121 steps/day, SD = 5592 steps/day, 95% CI of difference, 6726-7428 steps/day, P = .001, d = 1.76). In addition, significant decreases in BF% and waist circumference were observed in the intervention group post 6 weeks (mean change for BF% = -4.5%, mean change for WC = -1.7 cm, P = .001). School-based integrated curriculum and pedometer interventions provide a feasible and effective mechanism for increasing habitual PA in primary school children from deprived SA backgrounds.

Effect of arousing stimuli on circulating corticosterone and the circadian rhythms of luteinizing hormone (LH) surges and locomotor activity in estradiol-treated ovariectomized (ovx+EB) Syrian hamsters

In most proestrous hamsters, novel wheel exposure phase advances activity rhythms and blocks the preovulatory LH surge, which occurs 2h earlier the next day. Because wheel immobilization does not prevent these effects we hypothesized that arousal alone blocks and phase advances the LH surge. Ovariectomized (ovx) hamsters received a jugular vein cannula and estradiol benzoate (EB) or vehicle was injected sc. The next day (Day 1), at zeitgeber time (ZT) 4-5 (ZT 12 = lights off), after obtaining a blood sample, each hamster was exposed to constant darkness (DD), and either remained in her home cage or was transferred to a new cage and exposed to a running wheel or a 2-hour arousal paradigm. Blood samples were obtained in dim red light and activity was recorded hourly until ~ZT 10-11 on Days 1 and 2. For the next 1-2 weeks, activity was monitored in DD. Plasma LH and corticosterone were assessed by RIA. Novel wheel exposure or arousal at ZT 4 greatly attenuated the Day 1 LH surge in ovx+EB hamsters, and phase advanced the Day 2 LH surge by about 2h. In proestrous hamsters, novel wheel exposure led to a prolonged (>2h) increase in corticosterone levels only when LH surges were blocked. Phase advances in activity rhythms were enhanced by estradiol and arousal. The results suggest that estradiol modulates the effectiveness of non-photic stimuli. The role of the increased activity of the hypothalamic-pituitary-adrenal axis associated with novel wheel-induced attenuation of LH surges in ovx+EB hamsters remains to be determined.

Effects of acute caffeine ingestion on resistance training performance and perceptual responses during repeated sets to failure

AIM

The aim of the present study was to evaluate the effect of oral caffeine ingestion during repeated sets of resistance.

METHODS

Fourteen moderately resistance-trained men (20.9 ± 0.36 years and 77.62 ± 2.07 kg of body weight) ingested a dose of caffeine (5 mg.kg-1) or placebo prior to 3 sets of bench press and 3 sets of leg press exercises, respectively. The study used a double-blind, counterbalanced, crossover design. Repetitions completed and total weight lifted were recorded in each set. Readiness to invest in both physical (RTIPE) and mental (RTIME) effort were assessed prior each set, and rating of perceived exertion (RPE) was recorded after each set. Rest and peak heart rates were determined via telemetry.

RESULTS

Caffeine ingestion result in increased number of repetitions to failure in bench press (F[1,13]=6.16, P=0.027) and leg press (F[1,13]=9.33, P=0.009) compared to placebo. The sum of repetitions performed in the 3 sets was 11.60% higher in bench press (26.86 ± 1.74; caffeine: 30.00 ± 1.87; P=0.027) and 19.10% in leg press (placebo: 40.0 ± 4.22; caffeine: 47.64 ± 4.69; P=0.009). Also, RTIME was increased in the caffeine condition both in bench press (F[1,13]=7.02, P=0.02) and in leg press (F[1,13]=5.41, P=0.03). There were no differences in RPE, RTIPE and HR (P>0.05) across conditions.

CONCLUSION

Acute caffeine ingestion can improve performance in repeated sets to failure and increase RTIME in resistance-trained men.

Increased fragmentation of sleep-wake cycles in the 5XFAD mouse model of Alzheimer's disease

Sleep perturbations including fragmented sleep with frequent night-time awakenings and daytime naps are common in patients with Alzheimer's disease (AD), and these daily disruptions are a major factor for institutionalization. The objective of this study was to investigate if sleep-wake patterns are altered in 5XFAD mice, a well-characterized double transgenic mouse model of AD which exhibits an early onset of robust AD pathology and memory deficits. These mice have five distinct human mutations in two genes, the amyloid precursor protein (APP) and Presenilin1 (PS1) engineered into two transgenes driven by a neuron-specific promoter (Thy1), and thus develop severe amyloid deposition by 4 months of age. Age-matched (4-6.5 months old) male and female 5XFAD mice were monitored and compared to wild-type littermate controls for multiple sleep traits using a non-invasive, high throughput, automated piezoelectric system which detects breathing and gross body movements to characterize sleep and wake. Sleep-wake patterns were recorded continuously under baseline conditions (undisturbed) for 3 days and after sleep deprivation of 4h, which in mice produces a significant sleep debt and challenge to sleep homeostasis. Under baseline conditions, 5XFAD mice exhibited shorter bout lengths (14% lower values for males and 26% for females) as compared to controls (p<0.001). In females, the 5XFAD mice also showed 12% less total sleep than WT (p<0.01). Bout length reductions were greater during the night (the active phase for mice) than during the day, which does not model the human condition of disrupted sleep at night (the inactive period). However, the overall decrease in bout length suggests increased fragmentation and disruption in sleep consolidation that may be relevant to human sleep. The 5XFAD mice may serve as a useful model for testing therapeutic strategies to improve sleep consolidation in AD patients.

The effects of arm crank ergometry, cycle ergometry and treadmill walking on postural sway in healthy older females

Older adults are increasingly being encouraged to exercise but this may lead to muscle fatigue, which can adversely affect postural stability. Few studies have investigated the effects of upper body exercise on postural sway in groups at risk of falling, such as the elderly. The purpose of this study was to compare the effects arm crank ergometry (ACE), cycle ergometry (CE) and treadmill walking (TM) on postural sway in healthy older females. In addition, this study sought to determine the time necessary to recover postural control after exercise. A total of nine healthy older females participated in this study. Participants stood on a force platform to assess postural sway which was measured by displacement of the centre of pressure before and after six separate exercise trials. Each participant completed three incremental exercise tests to 85% of individual's theoretical maximal heart rate (HRMAX) for ACE, CE and TM. Subsequent tests involved 20-min of ACE, CE and TM exercise at a relative workload corresponding to 50% of each individual's predetermined heart rate reserve (HRE). Post fatigue effects and postural control recovery were measured at different times after exercise (1, 3, 5, 10, 15 and 30-min). None of the participants exhibited impaired postural stability after ACE. In contrast, CE and TM elicited significant post exercise balance impairments, which lasted for ∼ 10 min post exercise. We provide evidence of an exercise mode which does not elicit post exercise balance impairments. Older adults should exercise caution immediately following exercise engaging the lower limbs to avoid fall risk.

The effect of caffeine ingestion on functional performance in older adults

Caffeine is a widely used nutritional supplement which has been shown to enhance both physical and cognitive performance in younger adults. However, few studies have assessed the effect of caffeine ingestion on performance, particularly functional performance in older adults. The present study aims to assess the effect of acute caffeine ingestion on functional performance, manual dexterity and readiness to invest effort in older adults.

METHODS

19 apparently healthy, volunteers (10 females and 9 males aged 61-79; 66 ± 2 years) performed tests of functional fitness and manual dexterity post ingestion of caffeine (3mg*kg-1) or placebo in a randomised order. Pre and 60 minutes post ingestion, participants also completed measures of readiness to invest physical (RTIPE) and mental (RTIME) effort.

RESULTS

A series of repeated measures ANOVAS indicated enhanced performance in the following functional fitness tests; arm curls (P = .04), 8 foot up and go (P = .007), six minute walk (P = .016). Manual dexterity was also improved in the presence of caffeine (P = .001). RTIME increased (P = .015) pre to post ingestion in the caffeine condition but not in the placebo condition. There were no significant main effects or interactions for RTIPE or gender in any analysis (all P > .05).

CONCLUSIONS

The results of this study suggest that acute caffeine ingestion positively enhances functional performance, manual dexterity and readiness to invest effort in apparently healthy older adults.

The influence of age and weight status on cardiac autonomic control in healthy children: a review

Heart rate variability (HRV) analyses can provide a non-invasive evaluation of cardiac autonomic activity. How autonomic control normally develops in childhood and how this is affected by obesity remain incompletely understood. In this review we examine the evidence that childhood age and weight status influence autonomic control of the heart as assessed using HRV. Electronic databases (Pubmed, EMBASE and Cochrane Library) were searched for studies examining HRV in healthy children from birth to 18 years who adhered to the Task Force (1996) guidelines. Twenty-four studies met our inclusion criteria. Seven examined childhood age and HRV. A reduction in 24-hour LF:HF was reported from birth to infancy (1 year), while overall HRV (SDNN) showed a marked and progressive increase. From infancy to early-to-late childhood (from 12 months to 15 years) LF:HF ratio was reported to decline further albeit at a slower rate, while RMSSD and SDNN increased. Twenty studies examined the effects of weight status and body composition on HRV. In a majority of studies, obese children exhibited reductions in RMSSD (n = 8/13), pNN50% (n = 7/9) and HF power (n = 14/18), no difference was reported for LF (n = 10/18), while LF:HF ratio was elevated (n = 10/15). HRV changes during childhood are consistent with a marked and progressive increase in cardiac parasympathetic activity relative to sympathetic activity. Obesity disrupts the normal maturation of cardiac autonomic control.

Low socio-economic environmental determinants of children's physical activity in Coventry, UK: A Qualitative study in parents

Background

Children's physical activity (PA) is affected by socio-economic status (SES) and the environment. Children are not fully autonomous in their decision making; parental decisions thus affect how children utilise their surrounding environments for PA. The aim was to examine environmental influences on children's PA from a qualitative perspective in parents from low SES wards in Coventry, UK.

Method

59 parents of children in year 4 (aged 8–9years) completed the ALPHA environmental questionnaire. 16 of these parents took part in focus group discussions examining environmental facilitators and barriers to their child's PA (March–April, 2013).

Results

Emerging themes related to physical (i.e. poor access, safety and quality of the neighbourhood) and social environment (i.e. ‘rough’ neighbourhood due to crime and anti-social behaviour) influences on the PA behaviour of children. The parents believed these environmental factors resulted in the children engaging in greater sedentary activity (watching TV) indoors. The school environment was perceived as a supportive physical environment for children's PA behaviour.

Conclusion

Parent's perceptions of an unsupportive physical and social environment restrict children's opportunities to play outside and be physically active and may lead to increased body fat (BF). Schools provide a supportive environment for children from low SES to be physically active in.

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Qualitative study exploring the effect of parental perceptions on child's physical activity.

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Poor perceptions of the physical and social environment limit children's physical activity.

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Parents' safety concerns limit children's physical activity to indoors.

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Religious practice limits time available for physical activity in Muslim children.

Effect of heavy back squats on repeated sprint performance in trained men

AIM

This study examined the impact of post activation potentiation on repeated sprint performance in trained Rugby Union players.

METHODS

Ten, male, professional Rugby Union players (mean age=25.2±5.02 years) performed 7, 30-meter sprints, separated by 25 seconds, 4 minutes following back squats (90% 1 repetition maximum) or a control condition performed in a counterbalanced order.

RESULTS

Significant condition X sprint interactions for 10-meter (P=0.02) and 30-meter (P=0.05) indicated that times were significantly faster in the PAP condition for sprints 5, 6 and 7 across both distances. Fatigue rate was also significantly lower in the PAP condition for 10-meter (P=0.023) and 30-meter (P=0.006) sprint running speed.

CONCLUSION

This study evidences that a heavy resistance exercise stimulus administered four minutes prior to repeated sprints can offset the decline in sprint performance seen during subsequent maximal sprinting over 10 and 30-meters in Rugby Union players.

Low socio-economic environmental determinants of children's physical activity in Coventry, UK: A Qualitative study in parents

BACKGROUND

Children's physical activity (PA) is affected by socio-economic status (SES) and the environment. Children are not fully autonomous in their decision making; parental decisions thus affect how children utilise their surrounding environments for PA. The aim was to examine environmental influences on children's PA from a qualitative perspective in parents from low SES wards in Coventry, UK.

METHOD

59 parents of children in year 4 (aged 8-9years) completed the ALPHA environmental questionnaire. 16 of these parents took part in focus group discussions examining environmental facilitators and barriers to their child's PA (March-April, 2013).

RESULTS

Emerging themes related to physical (i.e. poor access, safety and quality of the neighbourhood) and social environment (i.e. 'rough' neighbourhood due to crime and anti-social behaviour) influences on the PA behaviour of children. The parents believed these environmental factors resulted in the children engaging in greater sedentary activity (watching TV) indoors. The school environment was perceived as a supportive physical environment for children's PA behaviour.

CONCLUSION

Parent's perceptions of an unsupportive physical and social environment restrict children's opportunities to play outside and be physically active and may lead to increased body fat (BF). Schools provide a supportive environment for children from low SES to be physically active in.

Objectively measured patterns of physical activity in primary school children in Coventry: the influence of ethnicity

AIMS

The aetiology of increased metabolic risk in South Asians is incompletely understood, but may include modifiable factors such as physical activity. This study assessed patterns of physical activity in UK primary school children and examined the influence of ethnicity.

METHODS

We studied a community sample of children aged 8-9 years attending primary schools in Coventry, UK. One hundred and sixty-one children wore combined physical activity and heart rate monitors for 7 days. Levels of activity and energy expenditure were compared between White European (n = 96) and South Asian children (n = 65). Patterns of physical activity during the school week were also described.

RESULTS

Seventy-three per cent of White Europeans compared with only 35% of South Asians achieved international recommendations of 60 minutes of moderate to vigorous physical activity daily (P < 0.0000). South Asians were less active during the week (106 ± 28 vs. 120 ± 32 counts/min, respectively, P = 0.0054) and at weekends (92 ± 34 vs. 108 ± 54 counts/min, P = 0.0118) compared with White Europeans. There were differences in energy expenditure with lower physical activity levels in South Asians (daily average 1.68 ± 0.13 vs. 1.76 ± 0.17, P < 0.0001). Differences were attributable to less activity after school in South Asians (97 ± 29 vs. 120 ± 43 counts/min, P < 0.0000) as daytime activity was comparable between groups (120 ± 41 vs. 124 ± 39 counts/min, P > 0.05).

CONCLUSION

South Asian children in Coventry do significantly less physical activity than White Europeans, mainly attributable to differences in after-school activity. Ethnically tailored interventions should explore whether physical activity can be increased in South Asian children and, if so, whether this increased physical activity improves metabolic health.

Acute caffeine ingestion enhances performance and dampens muscle pain following resistance exercise to failure

This double-blind, within-subjects experiment examined the effects of acute caffeine ingestion on perceptions of muscle pain following a bout of high-intensity, upper-body resistance exercise to failure. Moderately trained males (N.=18) ingested a dose of caffeine (5 mg · kg-1) or placebo in a randomised and counterbalanced order and 1 hour later completed bench press exercise to failure at an intensity of 60% 1 repetition maximum. Repetitions completed was taken as a measure of performance, peak heart rate was determined via heart rate telemetry during the exercise bout, rating of perceived exertion (RPE) and upper body muscle pain was recorded immediately upon failure of the exercise task and peak blood lactate concentration was determined post-exercise. Caffeine resulted in improved repetitions to failure (t [17]=3.119, P=0.006), greater peak blood lactate (t [17] =5.080, P=0.0001) and lower RPE (t 17=-3.431, P=0.003) compared to placebo. Muscle pain perception was also significantly lower in the caffeine condition compared to placebo (t [17]=-2.567, P=0.04). These results support prior studies using aerobic based exercise modes in suggesting that caffeine ingestion can dampen exercise-induced muscle pain. Specifically, caffeine ingestion enhances muscular strength performance and reduces upper body muscle pain perception immediately following a bout of high-intensity resistance exercise to failure.

Novel wheel running blocks the preovulatory luteinizing hormone surge and advances the hamster circadian pacemaker

In rodents, the preovulatory luteinizing hormone (LH) surge is timed by a circadian rhythm. We recently reported that a phenobarbital-induced delay of the estrous cycle in Syrian hamsters is associated with an approximately 2-h phase advance in both the circadian locomotor activity rhythm and the timing of the LH surge. The following study tests the hypothesis that a >2-h nonpharmacological phase advance in the circadian pacemaker that delays the estrous cycle by a day will also phase advance the LH surge by approximately 2 h. Activity rhythms were continuously monitored in regularly cycling hamsters using running wheels or infrared detectors for about 10 days prior to jugular cannulation. The next day, on proestrus, hamsters were transferred to the laboratory for 1 of 3 treatments: transfer to a "new cage" (and wheel) from zeitgeber time (ZT) 4 to 8 (with ZT12 defined as time of lights-off), or exposure to a "novel wheel" at ZT5 or ZT1. All animals were then placed in constant dark (DD). Blood samples were obtained just before onset of DD and hourly for the next 6 h, on that day and the next day for determination of plasma LH concentrations. Running activity was monitored in DD for about 10 more days. Transfer to a novel wheel at either ZT5 or ZT1 delayed the LH surge to day 2 in most hamsters, whereas exposure to a new cage did not. Only the delayed LH surges were phase advanced at least 2.5 h on average in all 3 groups. However, wheel-running activity was similarly phase advanced in all 3 groups regardless of the timing of the LH surge; thus, the phase advances in circadian activity rhythms were not associated with the 1-day delay of the LH surge. Interestingly, the number of wheel revolutions was closely associated with the 1-day delay of LH surges following exposure to a novel wheel at either ZT1 or ZT5. These results suggest that the intensity of wheel running (or an associated stimulus) plays an important role in the circadian timing mechanism for the LH surge.

Further examination of presumptive Rhizobium trifolii mutants that nodulate Glycine max

Two recent reports described the isolation of derivatives of a Rhizobium trifolii strain that had gained the ability to nodulate Glycine max and Vigna radiata and that had demonstrated altered patterns of carbon source utilization, free-living nitrogen fixation, and hydrogen uptake. More extensive characterization of these strains now supports the conclusion that these strains are R. japonicum and are not derived from the putative parent R. trifolii.

Photic influences on the developing mammal

In adult mammals, the daily light-dark cycle acts via the retinohypothalamic pathway to entrain the circadian clock in the suprachiasmatic nuclei (SCN) and to communicate information about daylength to photoperiodic species. Studies in rats show that during late fetal and early neonatal life, before the retinohypothalamic pathway has innervated the SCN, the maternal circadian system entrains the timing of the developing clock to prevailing lighting conditions. Although the nature of the maternal output signal(s) used to entrain the developing clock has not been elucidated, the maternal SCN are a necessary component of maternal entrainment during both prenatal and postnatal life. Maternal entrainment of the fetal and neonatal clock thus ensures that the developing circadian system is synchronized to the outside world until maturation of the retinohypothalamic pathway permits direct photic entrainment. The maternal circadian system is not only necessary for entrainment of the developing circadian system, but recent studies suggest it may also provide the immature mammal with important photoperiodic information. In the montane vole (Microtus montanus) and the Djungarian hamster (Phodopus sungorus), the prenatal photoperiod affects postnatal photoperiodic responses, and cross-fostering experiments show that this information about daylength is perceived by the fetus. This prenatal information, in conjunction with postnatal perception of photoperiod, allows the developing animal to determine which way the season is changing and to modify the rate of reproductive maturation accordingly.

TLR4-initiated and cAMP-mediated abrogation of bacterial invasion of the bladder

The remarkable resistance of the urinary tract to infection has been attributed to its physical properties and the innate immune responses triggered by pattern recognition receptors lining the tract. We report a distinct TLR4 mediated mechanism in bladder epithelial cells (BECs) that abrogates bacterial invasion, a necessary step for successful infection. Compared to controls, uropathogenic type 1 fimbriated Escherichia coli and Klebsiella pneumoniae invaded BECs of TLR4 mutant mice in 10-fold or greater numbers. TLR4 mediated suppression of bacterial invasion was linked to increased intracellular cAMP levels which negatively impacted Rac-1 mediated mobilization of the cytoskeleton. Artificially increasing intracellular cAMP levels in BECs of TLR4 mutant mice restored resistance to type 1 fimbriated bacterial invasion. This finding reveals a novel function for TLR4 and another facet of bladder innate defense.

A novel TLR4-mediated signaling pathway leading to IL-6 responses in human bladder epithelial cells

The vigorous cytokine response of immune cells to Gram-negative bacteria is primarily mediated by a recognition molecule, Toll-like receptor 4 (TLR4), which recognizes lipopolysaccharide (LPS) and initiates a series of intracellular NF-κB–associated signaling events. Recently, bladder epithelial cells (BECs) were reported to express TLR4 and to evoke a vigorous cytokine response upon exposure to LPS. We examined intracellular signaling events in human BECs leading to the production of IL-6, a major urinary cytokine, following activation by Escherichia coli and isolated LPS. We observed that in addition to the classical NF-κB–associated pathway, TLR4 triggers a distinct and more rapid signaling response involving, sequentially, Ca²⁺, adenylyl cyclase 3–generated cAMP, and a transcriptional factor, cAMP response element–binding protein. This capacity of BECs to mobilize secondary messengers and evoke a more rapid IL-6 response might be critical in their role as first responders to microbial challenge in the urinary tract.

In spite of frequent cross contamination by bacteria from the gut, urinary tract infections are relatively infrequent. Although much of the credit goes to cells lining the urinary tract, such as bladder cells, how this is achieved remains unclear. Human bladder cells display, on their surfaces, special molecules called Toll-like receptors, which sense the presence of bacteria and trigger the cells to release a variety of chemicals called cytokines. Cytokines contribute to the recruitment of phagocytic cells from the blood to the site of infection to clear bacteria. In this paper, we reveal that the Toll-like receptor–initiated intracellular signals leading to the production of cytokines by bladder cells involve the same pathway seen in other cells, as well as an additional and more rapid signaling pathway. Rapid production of cytokines by bladder cells will facilitate early clearance of bacteria. Additionally, possession of multiple signaling pathways by bladder cells for producing cytokines is advantageous because bacteria that infect the urinary tract have the capability to suppress certain signaling events that lead to cytokine production by bladder cells.

Anthropometric and physiological characteristics of junior elite volleyball players

OBJECTIVES

To investigate the anthropometric and physiological characteristics of junior elite volleyball players.

METHOD

Twenty five national level volleyball players (mean (SD) age 17.5 (0.5) years) were assessed on a number of physiological and anthropometric variables. Somatotype was assessed using the Heath-Carter method, body composition (% body fat, % muscle mass) was assessed using surface anthropometry, leg strength was assessed using a leg and back dynamometer, low back and hamstring flexibility was assessed using the sit and reach test, and the vertical jump was used as a measure of lower body power. Maximal oxygen uptake was predicted using the 20 m multistage fitness test.

RESULTS

Setters were more ectomorphic (p<0.05) and less mesomorphic (p<0.01) than centres. Mean (SD) of somatotype (endomorphy, mesomorphy, ectomorphy) for setters and centres was 2.6 (0.9), 1.9 (1.1), 5.3 (1.2) and 2.2 (0.8), 3.9 (1.1), 3.6 (0.7) respectively. Hitters had significantly greater low back and hamstring flexibility than opposites. Mean (SD) for sit and reach was 19.3 (8.3) cm for opposites and 37 (10.7) cm for hitters. There were no other significant differences in physiological and anthropometric variables across playing positions (all p>0.05).

CONCLUSION

Setters tend to be endomorphic ectomorphs, hitters and opposites tend to be balanced ectomorphs, whereas centres tend to be ectomorphic mesomorphs. These results indicate the need for sports scientists and conditioning professionals to take the body type of volleyball players into account when designing individualised position specific training programmes.

Bacterial penetration of the mucosal barrier by targeting lipid rafts

Several traditionally extracellular pathogens not known to possess invasive capacity have been shown to invade various mucosal epithelial cells. The mucosal epithelium performs an important barrier function and is not typically amenable to bacterial invasion. Valuable clues to the underlying basis for bacterial invasion have emerged from recent studies examining the invasion of bladder epithelial cells by uropathogenic Escherichia coli and alveolar epithelial cells by Pseudomonas aeruginosa. In both cases, bacterial invasion is achieved through targeting of molecules specifically found within distinct glycosphingolipid- and cholesterol-enriched microdomains called lipid rafts. The importance of lipid rafts in promoting bacterial invasion was shown as disruptors of lipid rafts blocked cellular invasion by both E. coli and P. aeruginosa. In addition, molecular components of lipid rafts were found to be highly enriched in membranes encasing these intracellular bacteria. Furthermore, caveolin proteins, which serve to stabilize and organize lipid raft components, are necessary for bacterial entry. Taken together, targeting of lipid rafts appears to be an effective but poorly recognized mechanism used by pathogenic bacteria to circumvent the mucosal barriers of the host.

The Distinct Binding Specificities Exhibited by Enterobacterial Type 1 Fimbriae Are Determined by Their Fimbrial Shafts

Type 1 fimbriae of enterobacteria are heteropolymeric organelles of adhesion composed of FimH, a mannose-binding lectin, and a shaft composed primarily of FimA. We compared the binding activities of recombinant clones expressing type 1 fimbriae from Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium for gut and uroepithelial cells and for various soluble mannosylated proteins. Each fimbria was characterized by its capacity to bind particular epithelial cells and to aggregate mannoproteins. However, when each respective FimH subunit was cloned and expressed in the absence of its shaft as a fusion protein with MalE, each FimH bound a wide range of mannose-containing compounds. In addition, we found that expression of FimH on a heterologous fimbrial shaft, e.g. K. pneumoniae FimH on the E. coli fimbrial shaft or vice versa, altered the binding specificity of FimH such that it closely resembled that of the native heterologous type 1 fimbriae. Furthermore, attachment to and invasion of bladder epithelial cells, which were mediated much better by native E. coli type 1 fimbriae compared with native K. pneumoniae type 1 fimbriae, were found to be dependent on the background of the fimbrial shaft (E. coli versus K. pneumoniae) rather than the background of the FimH expressed. Thus, the distinct binding specificities of different enterobacterial type 1 fimbriae cannot be ascribed solely to the primary structure of their respective FimH subunits, but are also modulated by the fimbrial shaft on which each FimH subunit is presented, possibly through conformational constraints imposed on FimH by the fimbrial shaft. The capacity of type 1 fimbrial shafts to modulate the tissue tropism of different enterobacterial species represents a novel function for these highly organized structures.

Bacterial penetration of bladder epithelium through lipid rafts

Type 1 fimbriated Escherichia coli represents the most common human uropathogen, owing much of its virulence to invasion of the uroepithelium, which is highly impermeable due to the preponderance of uroplakins and highly ordered lipid components. We sought to elucidate the molecular basis for E. coli invasion of the bladder epithelium by employing human 5637 bladder epithelial cells, and we found the following: (i) intracellular E. coli associated with caveolae and lipid raft components; (ii) RNA(i) reduction of caveolin-1 expression inhibited bacterial invasion; (iii) a signaling molecule required for E. coli invasion was located in lipid rafts and physically associated with caveolin-1; (iv) bacterial invasion was inhibited by lipid raft disrupting/usurping agents. In the mouse bladder, the E. coli type 1 fimbrial receptor, uroplakin Ia, was located in lipid rafts, and lipid raft disruptors inhibited E. coli invasion. Cumulatively, E. coli uroepithelial invasion occurs through lipid rafts, which, paradoxically, contribute to bladder impermeability.

Microbial entry through caveolae: variations on a theme

Caveolae and lipid rafts are increasingly being recognized as a significant portal of entry into host cells for a wide variety of pathogenic microorganisms. Entry through this mechanism appears to afford the microbes protection from degradation in lysosomes, though the level to which each microbe actively participates in avoiding lysosomal fusion may vary. Other possible variations in microbial entry through caveolae or lipid rafts may include (i) the destination of trafficking after entry and (ii) how actively the microbe contributes to the caveolae lipid/raft mediated entry. It seems that, though a wide variety of microorganisms are capable of utilizing caveolae/lipid rafts in various stages of their intracellular lifestyle, there can be distinct differences in how each microbe interacts with these structures. By studying these variations, we may learn more about the normal functioning of these cellular microdomains, and perhaps of more immediate importance, how to incorporate the use of these structures into the treatment of both infectious and non-infectious disease.

Cloning of the Streptococcus mutans gene encoding glucan binding protein B and analysis of genetic diversity and protein production in clinical isolates

Streptococcus mutans, the primary etiological agent of dental caries, produces several activities that promote its accumulation within the dental biofilm. These include glucosyltransferases, their glucan products, and proteins that bind glucan. At least three glucan binding proteins have been identified, and GbpB, the protein characterized in this study, appears to be novel. The gbpB gene was cloned and the predicted protein sequence contained several unusual features and shared extensive homology with a putative peptidoglycan hydrolase from group B streptococcus. Examination of gbpB genes from clinical isolates of S. mutans revealed that DNA polymorphisms, and hence amino acid changes, were limited to the central region of the gene, suggesting functional conservation within the amino and carboxy termini of the protein. The GbpB produced by clinical isolates and laboratory strains showed various distributions between cells and culture medium, and amounts of protein produced by individual strains correlated positively with their ability to grow as biofilms in an in vitro assay.

Porphyromonas gingivalis gingipains and adhesion to epithelial cells

Porphyromonas gingivalis is one of the principal organisms associated with adult periodontitis. Bacterial surface proteins such as fimbriae and gingipain hemagglutinin domains have been implicated as adhesins that actuate colonization of epithelium lining the gingival sulcus. We investigated the genetics of P. gingivalis adhesion to monolayers of epithelial cells using wild-type and gingipain mutant strains. These experiments suggested that arginine-specific gingipain (Rgp) catalytic activity modulated adhesion. From the data obtained with rgp mutants, we constructed a working hypothesis predicting that attachment and detachment of P. gingivalis to epithelial cells were mediated by gingipain adhesin and Rgp catalytic domains, respectively. A membrane-based epithelial cell binding assay, used to locate adhesins in extracellular fractions of wild-type and mutant strains, recognized gingipain peptides as adhesins rather than fimbriae. We developed a capture assay that demonstrated the binding of gingipain adhesin peptides to oral epithelial cells. The adherence of fimbrillin to epithelial cells was detected after heat denaturation of cell fractions. The prediction that Rgp catalytic activities mediated detachment was substantiated when the high level of attachment of an rgp mutant was reduced in the presence of wild-type cell fractions that contained gingipain catalytic activities.

Aging selectively suppresses vasoactive intestinal peptide messenger RNA expression in the suprachiasmatic nucleus of the Syrian hamster

Aging leads to many changes in the expression of circadian rhythms, including reduced amplitude, altered relationship to the environmental illumination cycle, and reduced sensitivity to phase resetting signals. Neuropeptide synthesizing neurons in the suprachiasmatic nucleus (SCN), the principal circadian pacemaker in mammals, play a role in regulating pacemaker function and in coupling the pacemaker to overt circadian rhythms. Aging may alter the activity of neuropeptide neurons in the SCN, which could be reflected in changes in mRNA expression. Therefore, this study investigated whether aging alters the level or rhythm of expression of neuropeptide mRNAs in the SCN of male Syrian hamsters, a well established model for the study of age-related changes in circadian rhythms. Three age groups of hamsters (young [3--5 months old], middle-aged [12--15 months old] and old [19--22 months old] were sacrificed at five times of day. Their brains were dissected and sections through the suprachiasmatic nucleus were prepared and used for in situ hybridization for mRNAs for vasoactive intestinal peptide (VIP), arginine vasopressin (AVP) and somatostatin (SS). Aging selectively decreased the SCN expression of VIP mRNA without affecting AVP mRNA or SS mRNA. Also, only AVP mRNA expression exhibited a robust 24-h rhythm, in contrast to previous findings in other species that VIP mRNA and SS mRNA, as well as AVP mRNA, exhibit 24-h rhythms in the SCN. The present findings suggest that age-related reductions in VIP mRNA expression may contribute to the alterations in entrainment and attenuated sensitivity to phase resetting signals that are characteristic of aging. Furthermore, the results demonstrate that neuropeptide gene expression in the SCN is differentially regulated by aging and varies among species.

Characterization of Porphyromonas gingivalis insertion sequence-like element ISPg5

Porphyromonas gingivalis, a black-pigmented, gram-negative anaerobe, is found in periodontitis lesions, and its presence in subgingival plaque significantly increases the risk for periodontitis. In contrast to many bacterial pathogens, P. gingivalis strains display considerable variability, which is likely due to genetic exchange and intragenomic changes. To explore the latter possibility, we have studied the occurrence of insertion sequence (IS)-like elements in P. gingivalis W83 by utilizing a convenient and rapid method of capturing IS-like sequences and through analysis of the genome sequence of P. gingivalis strain W83. We adapted the method of Matsutani et al. (S. Matsutani, H. Ohtsubo, Y. Maeda, and E. Ohtsubo, J. Mol. Biol. 196:445-455, 1987) to isolate and clone rapidly annealing DNA sequences characteristic of repetitive regions within a genome. We show that in P. gingivalis strain W83, such sequences include (i) nucleotide sequence with homology to tRNA genes, (ii) a previously described IS element, and (iii) a novel IS-like element. Analysis of the P. gingivalis genome sequence for the distribution of the least used tetranucleotide, CTAG, identified regions in many of the initial 218 contigs which contained CTAG clusters. Examination of these CTAG clusters led to the discovery of 11 copies of the same novel IS-like element identified by the repeated sequence capture method of Matsutani et al. This new 1,512-bp IS-like element, designated ISPg5, has features of the IS3 family of IS elements. When a recombinant plasmid containing much of ISPg5 was used in Southern analysis of several P. gingivalis strains, including clinical isolates, diversity among strains was apparent. This suggests that ISPg5 and other IS elements may contribute to strain diversity and can be used for strain fingerprinting.

Age-related changes in circadian responses to dark pulses

Aging involves many alterations in circadian rhythms, including a loss of sensitivity to both photic and nonphotic time signals. This study investigated the sensitivity of young and old hamsters to the phase advancing effect of a 6-h dark pulse on the locomotor activity rhythm. Each hamster was tested four times during a period of approximately 9 mo; periods of exposure to a 14-h photoperiod were alternated with the periods of exposure to constant light (20-80 lx), during which the dark pulses were administered. There was no significant difference in the phase shifts exhibited by the young (4-10 mo) and old hamsters (19-25 mo) or in the amount of wheel running activity displayed during each dark pulse. However, young hamsters had a significantly greater propensity to exhibit split rhythms immediately after the dark pulses. These results suggest that, although aging does not reduce the sensitivity of the circadian pacemaker to this nonphotic signal, it alters one property of the pacemaker, i.e., the flexibility of the coupling of its component oscillators.

Localization of serotonin(5A) receptors in discrete regions of the circadian timing system in the Syrian hamster

Endogenous serotonin and serotonergic drugs influence many aspects of circadian rhythms, including phase shifts, onset of locomotor activity, and period length and integrity of rhythms during exposure to constant light. The receptor subtype(s) mediating all of these circadian effects of serotonin has (have) not been identified. Immunoreactivity for the serotonin(5A) (5-HT(5A)) receptor has recently been identified in the rat suprachiasmatic nucleus (SCN). In this study, we investigated the distribution of the 5-HT(5A) receptors in four neural components of the circadian timing system (the SCN, the intergeniculate leaflet, and the median and dorsal raphe nuclei), in the Syrian hamster. Single and dual immunohistochemistry were conducted using an affinity-purified rabbit antibody generated against a peptide sequence unique to the 5-HT(5A) receptor, guinea pig anti-5-HT antisera and guinea pig anti-GABA antisera. For single labeling, immunoreactivity was visualized using DAB-nickel as the chromagen. All four regions showed strong, yet distinct, immunoreactivity for the 5-HT(5A) receptor. No specific labeling was present in the absorption or omission controls. For double labeling, immunoreactivity was visualized using immunofluorescence with Cy5- and FITC-labeled second antibodies followed by confocal microscopy. In the raphe nuclei, 5-HT-immunoreactivity and 5-HT(5A)-immunoreactivity were co-localized in cell bodies and axons. GABA-immunoreactive fibers surrounded some of the 5-HT(5A) receptor-immunoreactive cell bodies in the raphe nuclei. In conclusion, the 5-HT(5A) receptors are localized within several important neuroanatomical substrates of the circadian timekeeping system, and within the raphe nuclei, appear to be present on serotonin neurons. These findings suggest that some of the circadian effects of 5-HT may be mediated by the 5-HT(5A) receptor, which may function as a presynaptic autoreceptor.

Pleiotropic pigmentation mutants of Porphyromonas gingivalis

Porphyromonas gingivalis is a Gram-negative, black pigmented oral anaerobe associated with adult periodontitis. The adherence of the bacterium to junctional epithelial cells is the first step in infection and colonization. The molecular mechanisms and genetics of colonization are, as yet, not well understood, although it has been demonstrated that P. gingivalis fimbriae are involved in adhesion. In addition, cell surface cysteine proteinases may play a role either directly as adhesins or indirectly through their involvement in the biogenesis of fimbriae. A link has been established between cysteine proteinase-hemagglutinating activity and colongy pigmentation on blood agar. In this study a P. gingivalis ATCC 33277 transposon library was screened for white mutants. Pleiotropic mutants were identified with altered pigmentation, proteinase, hemagglutinin and haemolytic activities. Although the mutants fell into two classes based on the above phenotypes, by electron microscopy both classes showed increased fimbriation and decreased vesicle formation. Sequencing of genomic DNA flanking the transposon insertions revealed that one class of mutants carried disruptions in the gene encoding Lys-gingipain (kgp) and the other in a gene homologous to a glycosyl transferase. Potential roles for these genes in pigmentation, fimbriation, vesicle formation and attachment to epithelial cells are discussed.

Aging regulates 5-HT(1B) receptors and serotonin reuptake sites in the SCN

Middle age is associated with changes in circadian rhythms (e.g., alterations in the timing of the circadian wheel running rhythm) which resemble changes induced by selective destruction of the serotonergic input to the suprachiasmatic nucleus (SCN), the principal mammalian circadian pacemaker. We hypothesized that serotonergic neurotransmission in the SCN is decreased in middle-aged hamsters, as compared to young adults. This hypothesis was tested indirectly by investigating the effect of aging on two markers of serotonin neurotransmission, 5-HT(1B) receptors and serotonin reuptake sites, which are regulated by serotonin. Previous studies have shown that experimentally induced decreases in serotonergic neurotransmission increase 5-HT(1B) receptors but decrease serotonin reuptake sites. Quantitative autoradiography was conducted using [125I]iodocyanopindolol ([125I]ICYP) and [3H]paroxetine, selective radioligands for the 5-HT(1B) receptors and the serotonin reuptake sites, respectively. Consistent with the hypothesis, specific ([125I]ICYP binding was significantly elevated in the SCN of middle-aged hamsters, as compared to young hamsters. The results also showed that serotonin reuptake sites in the SCN were significantly increased in both middle-aged and old hamsters, as compared to young controls. This result could not have been caused by decreased serotonin release. Alternatively, increased serotonin reuptake, which would reduce serotonin levels in the synaptic cleft, may cause or contribute to the increase in 5-HT(1B) receptor binding in the SCN in middle aged animals. These results show that the SCN exhibits changes in serotonergic function during middle age, which has been characterized by changes in the expression of circadian rhythms. Because these changes occur during middle age, they probably reflect the aging process, rather than senescence or disease.

Identification and cloning of genes from Porphyromonas gingivalis after mutagenesis with a modified Tn4400 transposon from Bacteroides fragilis

Porphyromonas gingivalis is a gram-negative, black-pigmented, oral anaerobe strongly associated with adult periodontitis. Previous transposon mutagenesis studies with this organism were based on the Bacteroides transposon Tn4351. Characterization of Tn4351-disrupted genes by cloning has not been an efficient way to analyze large numbers of mutants and is further complicated by the high rate of cointegration of the suicide delivery vector containing Tn4351. In this study, we mutagenized P. gingivalis with a modified version of the Bacteroides fragilis transposon Tn4400. Plasmid pYT646B carrying the transposon was mobilized from Escherichia coli to P. gingivalis ATCC 33277 by conjugation. Both normal and inverse transposition frequencies were similar (3 x 10(-8)). However, the inverse transposon (Tn4400') contains a pBR322 replicon and a beta-lactamase gene; thus, the cloning of disrupted genomic DNAs from inverse transposition mutants was easily accomplished after ligation of genomic fragments and transformation into E. coli. Thousands of transconjugants could be obtained in a single mating experiment, and inverse transposition was random as demonstrated by Southern hybridization. By this procedure the disrupted genes from P. gingivalis pleiotropic mutants were quickly cloned, sequenced, and identified.

The formation of Uranus and Neptune in the Jupiter-Saturn region of the Solar System

Planets are believed to have formed through the accumulation of a large number of small bodies. In the case of the gas-giant planets Jupiter and Saturn, they accreted a significant amount of gas directly from the protosolar nebula after accumulating solid cores of about 5-15 Earth masses. Such models, however, have been unable to produce the smaller ice giants Uranus and Neptune at their present locations, because in that region of the Solar System the small planetary bodies will have been more widely spaced, and less tightly bound gravitationally to the Sun. When applied to the current Jupiter-Saturn zone, a recent theory predicts that, in addition to the solid cores of Jupiter and Saturn, two or three other solid bodies of comparable mass are likely to have formed. Here we report the results of model calculations that demonstrate that such cores will have been gravitationally scattered outwards as Jupiter, and perhaps Saturn, accreted nebular gas. The orbits of these cores then evolve into orbits that resemble those of Uranus and Neptune, as a result of gravitational interactions with the small bodies in the outer disk of the protosolar nebula.

Aging and photoperiod regulate glutamic acid decarboxylase(67) messenger RNA expression

Aging and short photoperiod exposure both induce similar long-term changes in circadian rhythms, including alterations in the timing and the amplitude of rhythms. Furthermore, these chronic conditions affect the function of the circadian pacemaker in the suprachiasmatic nuclei (SCN) by altering rhythmic expression of neuropeptide messenger RNAs (mRNAs). Because GABA modulates SCN neuronal activity, and GABAergic neurons innervate peptidergic neurons in the SCN, the present study investigated whether photoperiod or aging affect the expression of mRNA for GAD(67), the enzyme responsible for regulating the tonic levels of GABA. As a control for regional specificity, the reticular thalamic nucleus (RTN) was also examined. In situ hybridization for GAD(67) mRNA was performed on brain sections derived from Siberian hamsters exposed to a long day or a short day photoperiod for 15 days, and on brain sections from young (3-4 months old) and old (12-17 months old) Syrian hamsters exposed to a long photoperiod. The results showed that photoperiod and aging have different effects on GAD(67) mRNA expression. Exposure to short day photoperiod significantly increased GAD(67) mRNA expression in both the SCN and RTN of Siberian hamsters, while aging significantly decreased GAD(67) mRNA expression in the RTN of Syrian hamsters but had no effect on GAD(67) mRNA expression in the SCN. These findings suggest that modulation of GAD(67) mRNA expression in the SCN is associated with photoperiodic regulation of neuropeptide mRNA expression, but is not a common mechanism for chronic regulation of circadian rhythms. Also, GAD(67) mRNA expression in the RTN is differentially affected by photoperiod and aging.