The association between dog ownership or dog walking and fitness or weight status in childhood.

BACKGROUND: Health benefits of dog walking are established in adults: dog owners are on average more physically active, and those walking their dogs regularly have lower weight status than those who do not. However, there has been little research on children. OBJECTIVES: This study aimed to examine the association between dog ownership or dog walking and childhood fitness or weight status. METHODS: A survey of pet ownership and involvement in dog walking was combined with fitness and weight status measurements of 1021 9 to 10-year-old children in the Liverpool SportsLinx study. RESULTS: We found little evidence to support that children who live with, or walk with, dogs are any fitter or less likely to be obese than those who do not. CONCLUSIONS: This is an important finding, as it suggests that the activity that children currently do with dogs is not sufficient enough to impact weight status or fitness.

Physical activity guidelines and cardiovascular risk in children: a cross sectional analysis to determine whether 60 minutes is enough.

BACKGROUND: Physical activity reduces cardiovascular mortality and morbidity. The World Health Organisation (WHO) recommends children engage in 60 min daily moderate-to-vigorous physical activity (MVPA). The effect of compliance with this recommendation on childhood cardiovascular risk has not been empirically tested. To evaluate whether achieving recommendations results in reduced composite-cardiovascular risk score (CCVR) in children, and to examine if vigorous PA (VPA) has independent risk-reduction effects. METHODS: PA was measured using accelerometry in 182 children (9-11 years). Subjects were grouped according to achievement of 60 min daily MVPA (active) or not (inactive). CCVR was calculated (sum of z-scores: DXA body fat %, blood pressure, VO2peak, flow mediated dilation, left ventricular diastolic function; CVR score ≥ 1SD indicated 'higher risk'). The cohort was further split into quintiles for VPA and odds ratios (OR) calculated for each quintile. RESULTS: Active children (92 (53 boys)) undertook more MVPA (38 ± 11 min, P < 0.001), had greater VO2peak (4.5 ± 0.8 ml/kg/min P < 0.001), and lower fat % (3.9 ± 1.1 %, P < 0.001) than inactive. No difference were observed between active and inactive for CCVR or OR (P > 0.05). CCVR in the lowest VPA quintile was significantly greater than the highest quintile (3.9 ± 0.6, P < 0.05), and the OR was 4.7 times higher. CONCLUSION: Achievement of current guidelines has positive effects on body composition and cardiorespiratory fitness, but not CCVR. Vigorous physical activity appears to have beneficial effects on CVD risk, independent of moderate PA, implying a more prescriptive approach may be needed for future VPA guidelines.

Utility of the hypertriglyceridemic waist phenotype in the cardiometabolic risk assessment of youth stratified by body mass index.

BACKGROUND: It is unclear whether the hypertriglyceridemic waist phenotype (HTWP) can be used to identify those at most risk of cardiometabolic disorders. OBJECTIVES: The utility of the HTWP as a useful predictor of cardiometabolic risk in youth stratified by body mass index was assessed. METHODS: Three hundred and eighty-seven children (12-17.5 years) were used within this cross-sectional study. Participants were classified as normal weight or overweight/obese according to the International Obesity Task Force criteria. The HTWP phenotype was defined as having a waist circumference ≥90th percentile for age and gender with concomitant triglyceride concentrations ≥1.24 mmol L(-1) . Cardiometabolic risk profiles were compared using MANCOVA. RESULTS: Normal weight participants with the HTWP had significantly higher levels of C-reactive protein 2.6 ± 0.4 vs. 1.6 ± 0.3 mg L(-1) (P < 0.05) and cardiometabolic risk scores (1.3 ± 0.3 vs. -0.7 ± 0.2 and 2.1 ± 0.4 vs. -0.5 ± 0.2; both P < 0.05) compared with those of a normal weight without the HTWP. Overweight/obese participants with the HTWP had significantly higher C-reactive protein levels (3.5 ± 0.6 vs. 2.6 ± 0.5; P < 0.05) as well as both cardiometabolic risk scores (1.6 ± 0.6 vs. 0.9 ± 0.2 and 2.2 ± 0.6 vs. 0.8 ± 0.2; both P < 0.001) when compared with overweight/obese participants without the HTWP. CONCLUSIONS: The HTWP may serve as a simple and clinically useful approach to identify youth at increased cardiometabolic risk.

Assessment of biochemical liver markers, physical activity, fitness and body mass index for a cardiometabolic risk model in childhood.

AIM: The aim of this study was to investigate clustered cardiometabolic risk scores in healthy 10- to 12-year-olds using anthropometric characteristics, measurements of cardiorespiratory fitness (CRF) and physical activity and blood markers of metabolic disease. We also evaluated how including markers of liver cell injury would affect the clustered cardiometabolic risk assessment model. METHODS: This cross-sectional study focused on 99 children aged 10-12 years. The main outcome included assessing participants with increased and low cardiometabolic risk factors using a clustered risk score model that incorporated markers implicated in metabolic syndrome pathogenesis. Two clustered risk scores were calculated, one incorporating markers of liver cell injury. RESULTS: Children classified as 'increased risk' exhibited significantly lower CRF and higher body mass index Z-scores than their 'low-risk' peers. No significant differences in physical activity were observed. This trend remained unchanged when markers of liver injury were included in the clustered risk assessment model. CONCLUSION: The clustered risk score model is a scientifically robust method of cardiometabolic risk assessment, which reiterates the importance of weight reduction and CRF promotion in childhood. Our study did not show a significant contribution of liver injury markers, and further research is needed to evaluate their effect on cardiometabolic risk stratification in childhood.

Ten-year changes in positive and negative marker food, fruit, vegetables, and salad intake in 9-10 year olds: SportsLinx 2000-2001 to 2010-2011.

BACKGROUND: To investigate changes in intakes of 'negative' and 'positive' foods, fruit, vegetables, and salad in serial cohorts of 9-10-year-old children from 2000-2001 to 2010-2011. METHODS: For this serial, cross-sectional study, children in school year 5 (9-10 years of age) completed the SportsLinx Lifestyles Survey [n = 30,239 (15,336 boys and 14,903 girls)]. Changes in positive and negative food scores, and the proportion of boys and girls reportedly consuming fruit, vegetables and salad on the previous day to surveying, were investigated annually from 2000 to 2011. RESULTS: The consumption of negative foods declined and positive foods increased significantly compared to baseline. Positive changes in fruit, vegetables and salad consumption were observed over time, with the most recent cohort more likely to consume fruit, vegetables and salad compared to the 2000-2001 baseline. Girls displayed more favourable positive and negative food scores and were more likely to consume fruit, salad and vegetables across several study years compared to boys. CONCLUSIONS: The consumption of negative and positive foods, fruit, vegetables, and salad has improved over the last 10 years. In addition, girls appear to have better positive and negative food scores, and were more likely to consume fruit, vegetables and salad, across a number of study years or cohorts compared to boys. These encouraging findings suggest that children's food intake has improved since 2000. Furthermore, the data indicate that boys and girls may require separate or different healthy eating messages to further improve food intake.

The relationship between body mass index, aerobic performance and asthma in a pre-pubertal, population-level cohort.

PURPOSE: To assess the relationship between asthma, body mass index (BMI) and aerobic performance, as indicated by a shuttle test. METHODS: 20,577 participants (10,413 boys) from the SportsLinx serial cross-sectional study participated. Parental reports of asthma status and home postcode data were gathered from consent forms. Stature, sitting stature and body mass were measured and BMI, somatic maturity and indices of multiple deprivation scores (IMD) were derived. Performance on the 20 m multi-stage shuttle runs test (20mSRT) was used to estimate cardiorespiratory fitness (CRF). RESULTS: Asthma [F (1, 17,015) = 82.26, P < 0.01] and gender [F (1, 17,015) = 678.491, P < 0.001] significantly influenced 20mSRT. The addition of BMI, maturity and IMD to the model did not alter these significant effects. There was a significant interaction between 20mSRT and BMI [F (1, 16,723) = 132.80, P < 0.01], with a significant decrease in 20mSRT from the 50th BMI percentile upwards [t (16,699) = 36.88, P < 0.01]. Binary logistic regression revealed gender and 20mSRT to be significant predictors of asthma occurrence; BMI SDS just reached significance whilst maturity and IMD were not significant contributors to the model. CONCLUSIONS: This study demonstrates the negative influences of low CRF and high BMI on the risk of asthma occurrence in pre-pubertal children. Furthermore, it highlights the significant influence of BMI on CRF, revealing these effects to be manifest considerably below those BMI percentiles conventionally associated with being overweight or obese.

Changes in fitness, body mass index and obesity in 9-10 year olds.

BACKGROUND: The prevalence of obesity in children has increased substantially in recent years and, paediatric obesity and poor fitness are risk factors for disease. The present study aimed to assess changes in body mass index (BMI), the prevalence of obesity and changes in aerobic endurance over time in 9-10-year-old schoolchildren. METHODS: Participants were recruited by the SportsLinx project from primary schools across Liverpool. Height and weight data were used to calculate BMI. The prevalence of obesity and overweight were estimated using age- and sex-specific cut-off points. Performance on the 20-m multi-stage shuttle runs test (20 mMST) was used as a marker of aerobic endurance. Data were available for 13,418 (6572 boys, 6846 girls) 9-10-year-old children. Analysis of covariance was completed to assess year-on-year changes in BMI controlling for deprivation (IMD) and 20 mMST performance, and 20 mMST performance controlling for IMD and BMI. RESULTS: No significant changes in BMI from baseline were observed (P > 0.05). Obesity prevalence reduced in girls (2005 = 10.3%, 2008 = 8.52% in 2008). The data for boys showed no reductions in prevalence (2005 = 6.77%, 2008 = 7.87%). The most recent cohort for boys and two most recent cohorts for girls had lower levels of aerobic endurance than baseline (2004-2005) (P

Cardiorespiratory fitness and body mass index of 9-11-year-old English children: a serial cross-sectional study from 1998 to 2004.

OBJECTIVE: To examine the changes over time in cardiorespiratory fitness and body mass index (BMI) of children. DESIGN: Serial cross-sectional, population-based study. SETTING: Primary schools in Liverpool, UK. PARTICIPANTS: A total of 15,621 children (50% boys), representing 74% of eligible 9-11-year olds in the annual school cohorts between 1998/9 and 2003/4, who took part in a 20m multi-stage shuttle run test (20mMST). MAIN OUTCOME MEASURES: Weight, height, BMI (kg/m(2)) and obesity using the International Obesity Taskforce definition. RESULTS: Median (95% confidence interval) 20mMST score (number of runs) fell in boys from 48.9 (47.9-49.9) in 1998/9 to 38.1 (36.8-39.4) in 2003/4, and in girls from 35.8 (35.0-36.6) to 28.1 (27.2-29.1) over the same period. Fitness scores fell across all strata of BMI (P<0.001). Moreover, BMI increased over the same 6-year period even among children in fittest third of 20mMST. CONCLUSION: In a series of uniform cross-sectional assessments of school-aged children, BMI increased whereas cardiorespiratory fitness levels decreased within a 6-year period. Even among lean children, fitness scores decreased. Public health measures to reduce obesity, such as increasing physical activity, may help raise fitness levels among all children - not just the overweight or obese.

Autocrine regulation of milk secretion by a protein in milk.

Frequency or completeness of milk removal from the lactating mammary gland regulates the rate of milk secretion by a mechanism which is local, chemical and inhibitory in nature. Screening of goat's milk proteins in rabbit mammary explant cultures identified a single whey protein of M(r) 7600 able to inhibit synthesis of milk constituents. The active whey protein, which we term FIL (Feedback inhibitor of Lactation), also decreased milk secretion temporarily when introduced into a mammary gland of lactating goats. FIL was synthesized by primary cultures of goat mammary epithelial cells, and was secreted vectorially together with other milk proteins. N-terminal amino acid sequencing indicated that it is a hitherto unknown protein. The evidence indicates that local regulation of milk secretion by milk removal is through autocrine feedback inhibition by this milk protein.

Cloning of an Aspergillus niger invertase gene by expression in Trichoderma reesei.

The filamentous fungus Aspergillus niger produces two glycosylated forms of the sucrose-hydrolysing enzyme, invertase. In contrast, some Trichoderma species lack invertase and are unable to utilise sucrose as a sole carbon source. Using an A. niger genomic library constructed in a cosmid vector containing the ura5 gene of Podospora anserina as a selectable marker, and the T. reesei ura5- strain as a sucrose-minus recipient strain, an A. niger invertase gene (suc1) has been cloned by a sib selection procedure. PAGE and enzyme analysis confirmed that transformants had acquired invertase activity. The cloned gene contained DNA sequences which were complementary to the amino-acid sequences of tryptic peptides found in invertase purified from A. niger. The suc1 invertase gene can be used as a dominant selectable marker for the transformation of Trichoderma strains.

Purification and characterisation of an Aspergillus niger invertase and its DNA sequence.

A secreted invertase was purified 23-fold by ultrafiltration, ion-exchange, and gel filtration chromatography from the culture supernatant of 18 h sucrose-grown cultures of Aspergillus niger. The purified enzyme hydrolysed sucrose and raffinose but there was no detectable hydrolysis of inulin, melezitose or PNPG. Invertase activity was optimal at pH 5.5 and 50 degrees C. The molecular mass of reduced invertase was 115 kDa, as determined by SDS gel electrophoresis. The native molecular weight of between 225 kDa and 250 kDa, estimated by electrophoresis under non-denaturing conditions, suggests that the protein is a dimer of identical subunits. The suc1 gene encoding this protein was completely-sequenced. The translated sequence yields a protein of 566 amino acids with a calculated molecular mass of 61 kDa, suggesting that carbohydrates represent about 50% of the mass of the protein.