Prevalence and secular changes in abdominal obesity in Canadian adolescents and adults, 1981 to 2007-2009.

The purposes of this study were to: (i) provide contemporary estimates of the prevalence of abdominal obesity, as assessed by waist circumference (WC), in Canadian adolescents and adults; (ii) provide estimates of the prevalence of abdominal obesity within normal weight, overweight and obese body mass index categories and (iii) examine secular changes in abdominal obesity. Data were based on three national health surveys conducted in 1981, 1988 and 2007-2009. WC was measured at the mid-point between the last rib and iliac crest in all three surveys. The prevalence of Canadians with abdominal obesity increased with age and was higher in females than in males. In 12- to 19-year-old adolescents, the estimated prevalence of abdominal obesity was 1.8% in 1981, 2.4% in 1988 and 12.8% in 2007-2009. The corresponding values for 20- to 69-year-old adults were 11.4%, 14.2% and 35.6%. Between 1981 and 2007-2009, mean WC values increased by 4.2 cm in adolescent males, 6.7 cm in adolescent females, 6.5 cm in men and 10.6 cm in women. Within the 2007-2009 survey, 2.6% of normal weight adults had abdominal obesity, 35.3% of overweight adults had abdominal obesity and 93.0% of obese adults had abdominal obesity.

Testing the hierarchy of effects model: ParticipACTION's serial mass communication campaigns on physical activity in Canada.

The hierarchy of effects (HOE) model is often used in planning mass-reach communication campaigns to promote health, but has rarely been empirically tested. This paper examines Canada's 30 year ParticipACTION campaign to promote physical activity (PA). A cohort from the nationally representative 1981 Canada Fitness Survey was followed up in 1988 and 2002-2004. Modelling of these data tested whether the mechanisms of campaign effects followed the theoretical framework proposed in the HOE. Campaign awareness was measured in 1981. Outcome expectancy, attitudes, decision balance and future intention were asked in 1988. PA was assessed at all time points. Logistic regression was used to sequentially test mediating and moderating variables adjusting for age, sex and education. No selection bias was observed; however, relatively fewer respondents than non-respondents smoked or were underweight at baseline. Among those inactive at baseline, campaign awareness predicted outcome expectancy which in turn predicted positive attitude to PA. Positive attitudes predicted high decision balance, which predicted future intention. Future intention mediated the relationship between decision balance and sufficient activity. Among those sufficiently active at baseline, awareness was unrelated to outcome expectancy and inversely related to positive attitude. These results lend support to the HOE model, in that the effects of ParticipACTION's serial mass media campaigns were consistent with the sequential rollout of its messages, which in turn was associated with achieving an active lifestyle among those initially insufficiently active. This provides support to an often-used theoretical framework for designing health promotion media campaigns.

Adiposity, physical fitness and incident diabetes: the physical activity longitudinal study.

AIMS/HYPOTHESIS: The purpose of this study was to investigate the relationships among adiposity, physical activity, physical fitness and the development of diabetes in a diverse sample of Canadians. METHODS: The sample included 1,543 adults (709 men and 834 women) from the Canadian Physical Activity Longitudinal Study who were free of diabetes at baseline (1988). Several indicators of adiposity (BMI, waist circumference, WHR, sum of skinfold thicknesses), musculoskeletal fitness (sit-ups, push-ups, grip strength, trunk flexibility), cardiorespiratory fitness (maximal metabolic equivalents [METs]) and leisure-time physical activity levels were measured at baseline. Participants were followed until 2002-2004 for the ascertainment of new cases of diabetes. RESULTS: The 15.5-year cumulative incidence of diabetes was 5.0% (5.2% in men, 4.9% in women). Adiposity and physical fitness, but not physical activity, were significant predictors of diabetes after adjustment for age, sex and several covariates. For each standard deviation of the indicators of adiposity, the risk of diabetes was 99-194% higher. Conversely, the risk was 70 and 61% lower for each standard deviation of maximal METs and composite musculoskeletal fitness score, respectively. Receiver operating characteristic curve analyses confirmed that neither adiposity nor physical fitness provided a superior prediction of incident diabetes. CONCLUSIONS/INTERPRETATION: Adiposity and physical fitness were both important predictors of the development of diabetes in this cohort of Canadians.

Twelve-month effects of Canada on the Move: a population-wide campaign to promote pedometer use and walking.

Canada on the Move is a national campaign to promote pedometer use and walking among adult Canadians. The purpose of this paper is to investigate the initiative's impact on sufficient walking, defined here as at least an hour daily in the week prior to the survey. Data were collected via the national Canadian Physical Activity Monitor's rolling monthly sample throughout 2004. Population prevalence rates of walking were compared using Bonferroni-adjusted confidence intervals. Correlates of sufficient walking were estimated using odds ratios adjusted for age, sex, income and education. Message recall and pedometer ownership were associated with increased odds of self-reported walking. There was evidence of a campaign effect on walking behavior independent of secular trends. The increased likelihood of sufficient walking suggests an ongoing role for nationally funded public awareness campaigns. The effectiveness of health promotion to increase walking may be enhanced by combining motivational health-related messages with the dissemination and adoption of an easy-to-use tool for self-monitoring purposes.

Adiposity, adipose tissue distribution and mortality rates in the Canada Fitness Survey follow-up study.

OBJECTIVE: To compare mortality rates across indicators of adiposity and relative adipose tissue distribution in the Canadian population. SUBJECTS: The sample included 10,323 adult participants 20-69 y of age from the Canada Fitness Survey who were monitored for all-cause mortality over 13 y. METHODS: BMI, waist circumference (WC) and the sum of five skinfolds (SF5) were indicators of adiposity, and the first principal component of skinfold residuals (PC1) represented subcutaneous adipose tissue distribution. Proportional hazards regression was used to estimate relative mortality risk from mortality rates across levels of adiposity and adipose tissue distribution, controlling for the confounding effects of age, smoking status and alcohol consumption. RESULTS: :Significant curvilinear (J-shaped) relationships in men and linear relationships in women were observed between BMI, WC and SF5 and all-cause mortality rates. PC1 was not related to mortality rates in either men or women. In women, the inclusion of the other indicators of adiposity and adipose tissue distribution did not significantly add to the prediction of mortality rates beyond BMI; however, combinations of BMI and both WC and SF5 produced significant models in men. CONCLUSION: The results support the hypothesis that overall level of adiposity is an important predictor of all-cause mortality, more so than the relative distribution of subcutaneous body fat, once overall level of body fatness has been accounted for.

Original article underweight, overweight and obesity: relationships with mortality in the 13-year follow-up of the Canada Fitness Survey.

The purpose of this study was to determine the risk of all-cause mortality in the Canadian population across the new WHO/NIH BMI categories for the classification of overweight and obesity. The sample includes 10,725 adult participants (20-69 years) in the 1981 Canada Fitness Survey. A total of 593 deaths occurred during 13 years of follow-up. Hazard ratios (HR) for mortality were estimated using Cox proportional hazards models. Compared to normal weight individuals, there is an increased risk of mortality in the underweight category (HR 1.63, 95% CI 0.93-2.85) in addition to increasing levels of risk across the overweight (HR 1.16, 95% CI 0.96-1.39), obese class I (HR 1.25, 95% CI 0.96-1.65) and obese class II and III (HR 2.96, 95% CI 1.39-6.29) categories. Similar patterns were observed in sex-specific analyses. Underweight, overweight and obese Canadians are all at increased risk of mortality compared to those who are normal weight.

Signal polymorphism in the web-decorating spider Argiope argentata is correlated with reduced survivorship and the presence of stingless bees, its primary prey.

Many spiders, and in particular those in the genus Argiope, spin highly visible web decorations whose function and significance are the subject of spirited debate. In this work, we present data to address two of the competing hypotheses that fuel this controversy. In particular, we examine the relationship between the presence of web decorations and spider survivorship (predator-protection hypothesis) and the relationship between the presence of prey and spider decorating behavior (the prey-attraction hypothesis). Our laboratory studies reveal that the decorating behavior of the spider A. argentata has a genetic component but that the expression of decorating behavior tends to be elicited only when a spider is well fed. Furthermore, our field studies show that in the presence of abundant stingless bees, spider decorating behavior is induced. Nevertheless, our field surveys also suggest that spiders that decorate their webs show reduced survivorship. We propose that the high correlation between web decorating in the presence of stingless bees supports the hypothesis that A. argentata engage in decorating behavior when attracting or targeting specific prey types. However, we also propose that web decorations attract the predators of A. argentata because high-frequency decorators suffer lower survivorship than spiders that decorate moderately or rarely. These findings suggest that spider web decorating behavior is affected by conflicting selection pressures: the positive effect of prey attraction versus the negative effect of predator attraction. Due to the heritable component of decorating behavior, web decorating among A. argentata is likely to be particularly sensitive to the spider's local ecology as well as local patterns of gene flow.

Microstructural homogeneity of support silk spun by Eriophora fuliginea (C.L. Koch) determined by scanning X-ray microdiffraction.

Scanning X-ray microdiffraction (SXD) permits the 'imaging' in-situ of crystalline phases, crystallinity and texture in whole biopolymer samples on the micrometre scale. SXD complements transmission electron microscopy (TEM) techniques, which reach sub-nanometre lateral resolution but require thin sections and a vacuum environment. This is demonstrated using a support thread from a web spun by the orb-weaving spider Eriophora fuliginea (C.L. Koch). Scanning electron microscopy (SEM) shows a central thread composed of two fibres to which thinner fibres are loosely attached. SXD of a piece of support thread approximately 60 microns long shows in addition the presence of nanometre-sized crystallites with the beta-poly(L-alanine) structure in all fibres. The crystallinity of the thin fibres appears to be higher than that of the central thread, which probably reflects a higher polyalanine content of the fibroins. The molecular axis of the polymer chains in the central thread is orientated parallel to the macroscopic fibre axis, but in the thin fibres the molecular axis is tilted by about 71 degrees to the macroscopic fibre axis. A helical model is tentatively proposed to describe this morphology. The central thread has a homogeneous distribution of crystallinity along the macroscopic fibre axis.

Solid-state NMR relaxation studies of Australian spider silks.

Solid-state NMR techniques were used to study two different types of spider silk from two Australian orb-web spider species, Nephila edulis and Argiope keyserlingi. A comparison of (13)C-T(1) and (1)H-T(1rho) solid-state NMR relaxation data of the Ala Calpha, Ala Cbeta, Gly Calpha, and carbonyl resonances revealed subtle differences between dragline and cocoon silk. (13)C-T(1rho) and (1)H-T(1) relaxation experiments showed significant differences between silks of the two species with possible structural variations. Comparison of our data to previous (13)C-T(1) relaxation studies of silk from Nephila clavipes (A. Simmons et al., Macromolecules, 1994, Vol. 27, pp. 5235-5237) also supports the finding that differences in molecular mobility of dragline silk exist between species. Interspecies differences in silk structure may be due to different functional properties. Relaxation studies performed on wet (supercontracted) and dry silks showed that the degree of hydration affects relaxation properties, and hence changes in molecular mobility are correlated with functional properties of silk.

The function significance of silk decorations of orb-web spiders: a critical review of the empirical evidence.

A number of taxonomically diverse species of araneoid spiders adorn their orb-webs with conspicuous silk structures, called decorations or stabilimenta. The function of these decorations remains controversial and several explanations have been suggested. These include: (1) stabilising and strengthening the web; (2) hiding and concealing the spider from predators; (3) preventing web damage by larger animals, such as birds; (4) increasing foraging success; or (5) providing a sunshield. Additionally, they may have no specific function and are a consequence of stress or silk regulation. This review evaluates the strength of these explanations based on the evidence. The foraging function has received most supporting evidence, derived from both correlative field studies and experimental manipulations. This contrasts with the evidence provided for other functional explanations, which have not been tested as extensively. A phylogenetic analysis of the different decoration patterns suggests that the different types of decorations are as evolutionary labile as the decorations themselves: the analysis shows little homology and numerous convergences and independent gains. Therefore, it is possible that different types of decorations have different functions, and this can only be resolved by improved species phylogenies, and a combination of experimental and ultimately comparative analyses.

Evidence for diet effects on the composition of silk proteins produced by spiders.

Silks are highly expressed, secreted proteins that represent a substantial metabolic cost to the insects and spiders that produce them. Female spiders in the superfamily Araneoidea (the orb-spinning spiders and their close relatives) spin six different kinds of silk (three fibroins and three fibrous protein glues) that differ in amino acid content and protein structure. In addition to this diversity in silks produced by different glands, we found that individual spiders of the same species can spin dragline silks (drawn from the spider's ampullate gland) that vary in content as well. Freely foraging ARGIOPE: argentata (Araneae: Araneoidea), collected from 13 Caribbean islands, produced dragline silk that showed an inverse relationship between the amount of serine and glycine they contained. X-ray microdiffraction of the silks localized these differences to the amorphous regions of the protein that are thought to lend silks their elasticity. The crystalline regions of the proteins, which lend silks their strength, were unaffected. Laboratory experiments with ARGIOPE: keyserlingi suggested that variation in silk composition reflects the type of prey the spiders were fed but not the total amount of prey they received. Hence, it may be that the amino acid content (and perhaps the mechanical properties) of dragline silk spun by ARGIOPE: directly reflect the spiders' diet. The ability to vary silk composition and, possibly, function is particularly important for organisms that disperse broadly, such as Argiope, and that occupy diverse habitats with diverse populations of prey.

A comparison of the composition of silk proteins produced by spiders and insects.

Proteins that are highly expressed and composed of amino acids that are costly to synthesize are likely to place a greater drain on an organism's energy resources than proteins that are composed of ingested amino acids or ones that are metabolically simple to produce. Silks are highly expressed proteins produced by all spiders and many insects. We compared the metabolic costs of silks spun by arthropods by calculating the amount of ATP required to produce their component amino acids. Although a definitive conclusion requires detailed information on the dietary pools of amino acids available to arthropods, on the basis of the central metabolic pathways, silks spun by herbivorous, Lepidoptera larvae require significantly less ATP to synthesize than the dragline silks spun by predatory spiders. While not enough data are available to draw a statistically based conclusion, comparison of homologous silks across ancestral and derived taxa of the Araneoidea seems to suggest an evolutionary trend towards reduced silk costs. However, comparison of the synthetic costs of dragline silks across all araneomorph spiders suggests a complicated evolutionary pattern that cannot be attributed to phylogenetic position alone. We propose that the diverse silk-producing systems of the araneoid spiders (including three types of protein glues and three types of silk fibroin), evolved through intra-organ competition and that taxon-specific differences in the composition of silks drawn from homologous glands may reflect limited or fluctuating amino acid availability. The different functional properties of spider silks may be a secondary result of selection acting on different polypeptide templates.

Physical activity, physical fitness, and risk of dying.

We examined the relation between physical activity, physical fitness, and all-cause mortality in a national population-based study of Canadians. We followed men and women ages 20-69 years who had participated in the Canada Fitness Survey between 1981 and 1988. We assessed risk factors for 6,246 men and 8,196 women using multivariate Poisson regression analysis. At baseline, all subjects were asymptomatic according to self-reported screening questions for cardiovascular disease. Men who expended > or =0.5 kilocalories per kilogram of body weight per day (KKD) experienced a 20% decline in risk of mortality [rate ratio (RR) = 0.82; 95% confidence interval (CI) = 0.65-1.04] when compared with subjects expending <0.5 KKD. We observed a 30% decline in risk of mortality among women expending > or =3.0 KKD relative to those expending <0.5 KKD (RR = 0.71; 95% CI = 0.45-1.11). Similar patterns of risk were evident for both men and women when analyses were restricted to participation in nonvigorous activities. Those who perceived themselves to be of less than average fitness were at increased risk of mortality (male RR = 1.64, 95% CI = 1.21-2.22; female RR = 1.66, 95% CI = 1.21-2.26). Subjects with undesirable cardiorespiratory fitness levels were more likely to die, compared with those having recommended fitness levels (RR = 1.52; 95% CI = 0.72-3.18). Fifty-three per cent of men and 35% of women reported participating in a vigorous activity. The relation between daily energy expenditure and risk of mortality in these subjects could not be evaluated, as there were few deaths. Nonetheless, our results among participants reporting no vigorous activities support the hypothesis that there is a reduction in mortality risk associated with even modest participation in activities of low intensity.

Evolution of arthropod silks.

Silks belong to the class of molecules called structural proteins. The ability to produce silk proteins has evolved multiple times in the arthropods, and silk secreting glands have evolved via two different pathways. The comparative data and phylogenetic analyses in this review suggest that the silk-secreting systems of spiders and insects are homologous and linked to the crural gland (origin of systemic pathway to silk production) and cuticular secretions (origin of surficial pathway to silk production) of an onychophoran-like ancestor. The evolution of silk secreting organs via a surficial pathway is possible in adult and larval hexapods, regardless of their developmental mode. Silk secretion via a systemic pathway is possible in either adult or larval hexapods, but only larval insects have dedicated silk producing glands. Spiders, however, have evolved silk producing systems via both systemic pathway and surficial pathways, and a single individual retains both throughout its lifespan. Early in the evolution of spiders, silk glands were undifferentiated, suggesting that the number of silk secreting glands of any individual was related to the spider's energetic need to produce large quantities of protein. However, the complex silk-producing systems that characterize the aerial web-building spiders and the diverse types of proteins they produce suggest that their silks reflect the diverse and increasing number of ways in which spiders use them. Because the muscular and innervated spinnerets and spigots of spiders allow them to control fiber functional properties, silk proteins represent an avenue through which animal behavior may directly affect the molecular properties of a protein.

A reassessment of spinal stabilization in severe cerebral palsy.

A homogenous population of 37 institutionalized patients with scoliosis and severe cerebral palsy was evaluated to assess the impact of spinal stabilization on comfort, function, health, and ease of nursing care. Through a prospective care-burden study, a 34-month retrospective analysis, and a healthcare worker questionnaire, 17 fused patients with a mean current scoliosis of 35 degrees were compared with 20 nonfused patients with a mean scoliosis of 76 degrees. No clinically significant differences were noted in pain or pulmonary medication utilization or therapy, decubiti, function, or time for daily care. Nevertheless, the majority of healthcare workers believed that the fused patients were more comfortable.

Orthopedic aspects of musculoskeletal disease in children.

New information affecting the diagnosis and treatment of a wide variety of musculoskeletal conditions in children was published within the past year. A new etiology for acquired torticollis as well as a test to distinguish ocular and muscular torticollis were described. Familial predisposition for successful nonoperative treatment of interventional disk herniation was reported. Bone scintigraphy was shown to be helpful in defining the cause of occult gait disturbances, and accurate mapping of premature growth plate closure may soon be possible with magnetic resonance scans.

Subtalar arthrodesis for stabilization of valgus hindfoot in patients with cerebral palsy.

All patients with spastic cerebral palsy who underwent correction of valgus hindfoot by Grice extraarticular subtalar arthrodesis between 1971 and 1986 performed by two surgeons using an identical technique were reviewed. Twenty-nine patients (53 feet) were followed at an average of 8.9 years after operation. Traditional radiographic criteria for measurement of hindfoot alignment in skeletally mature individuals have poor reliability. Talar head uncovering is a useful and reproducible method for evaluation of hindfoot valgus in these patients. Five patients had progressive hindfoot or ankle deformity at latest follow-up. All five of these patients were spastic quadriplegics. There was no recurrence in the 17 patients who were less severely involved than the quadriplegic patients.

Aerial web-weaving spiders: Linking molecular and organismal processes in evolution.

Aerial web-weaving spiders display a wide variety of foraging behaviors that can be tied to the evolution of one family of proteins, the silks. In some cases, the physical structure and mechanical properties of silks alone determine the ecology of spiders: the habitats in which they forage, the prey they capture and their subsequent reproductive success. Future studies that integrate research on the physical structure of silks, the molecular genetics of silk synthesis and the foraging ecology of spiders in primitive and derived phylogenetic groups could reveal how molecular and organismal processes interact in evolution.