Flexible multibody approach in forward dynamic simulation of locomotive strains in human skeleton with flexible lower body bones

A method for bone strain estimation is examined in this article. The flexibility of a single bone in an otherwise rigid human skeleton model has been studied previously by various authors. However, in the previous studies, the effect of the flexibility of multiple bones on the musculoskeletal model behavior was ignored. This study describes a simulation method that can be used to estimate the bone strains at both tibias and femurs of a 65-year old Caucasian male subject. The verification of the method is performed by the comparison of the results with other studies available in literature. The results of the study show good correlation with the results of previous empirical studies. A damping effect of the flexible bones on the model is also studied in this paper.

Femoral neck geometry and hip fracture risk : the Geelong Osteoporosis Study

To determine the relationship between femoral neck geometry and the risk of hip fracture in post-menopausal Caucasian women, we conducted a retrospective study comparing the femoral neck dimensions of 62 hip fracture cases to those of 608 randomly selected controls. Measurements were made from dual-energy X-ray absorptiometry scans (Lunar DPX-L), using the manufacturers ruler function, and included: hip axis length (HAL), femoral neck axis length (FNAL), femoral neck width (FNW), femoral shaft width (FSW), medial femoral shaft cortical thickness (FSCT_med), and lateral femoral shaft cortical thickness (FSCT_lat). The fracture group was older (median age 78.3 years vs 73.8 years), lighter (median weight 59.9 kg vs 64.5 kg), and, after adjustment for age, taller (mean height 158.7±0.8 cm vs 156.7±0.2 cm) than the controls. Furthermore, bone mineral density was lower in this group (0.682±0.016 g/cm² vs 0.791±0.006 g/cm²). After adjustment for age, bone mineral content (BMC) or height, hip fracture patients had greater FNW (up to 6.6%) and FSW (up to 6.3%) than did the controls. Each standard deviation increase in FNW and FSW was associated with a 1.7-fold (95% CI 1.3–2.3) and a 2.4-fold (95% CI 1.8–3.2) increase in the fracture risk, respectively. BMC-adjusted FNAL was greater in the fracture group (+2.1%) than in the controls, while the age-adjusted FSCT_med was reduced (–7.2%). There was a trend towards longer HAL (up to 2.1%) after adjustment for age or BMC, and thinner age-adjusted FSCT_lat (–1.7%) in fracture patients that did not reach statistical significance. In multivariate analysis, the risk of hip fracture was predicted by the combination of age, FNW, FSW, BMC and FSCT_med. HAL was not analyzed because of the small number of HAL measurements among fracture cases. We conclude that post-menopausal women with hip fractures have wider femoral necks and shafts, thinner femoral cortices and longer femoral neck axis lengths than do women with no fractures. Alteration in hip geometry is associated with the risk of hip fracture.

Fracture thresholds revisited : Geelong Osteoporosis Study

Osteoporosis, in the absence of fracture, is defined as a deficit in bone mineral density (BMD) of 2.5 SD or more below the young adult reference mean in postmenopausal Caucasian populations. BMD is a measure of fracture risk but not the sole predictor. We have assessed a combination of easily accessible measures of age, height, weight, and BMD to improve fracture risk assessment. Women with low trauma fractures and a control group were recruited from south-eastern Australia. Discriminant analysis derived multivariate equations that assessed fracture risk. Age was not in the best models at the spine and forearm sites. Weight and height contributed to the relationship for the forearm sites only. At the proximal femur, the BMD level that separates fracture cases from nonfracture cases, increases with age. These separation levels of BMD were higher than the WHO's level of osteoporosis (T-score < −2.5 SD) at ages older than 62 years. This increasing BMD threshold with age suggests that other age-related risk factors assume increasing importance among the elderly.

Femoral neck dimensions are unlikely to be associated with age at menarche

Hip axis length (HAL) has been reported as an independent risk factor for hip fracture. Later puberty may increase bone size because of delayed epiphyseal fusion. We sought to identify associations between bone size at the proximal femur with age at menarche and other indices of growth such as stature. Femoral neck dimensions were measured from dual-energy X-ray absorptiometry scans of the proximal femur in a random sample of 203 premenopausal Caucasian women (age 20–30 years). There were no associations between age at menarche and HAL, femoral axis length (FAL) or femoral neck width (FNW). Age at menarche was associated with height (r= 0.2, p= 0.02). Variations in HAL, FAL and FNW do not appear to be related to age at menarche.

Nicotine dependence in a prospective population-based study of adolescents : the protective role of a functional tyrosine hydroxylase polymorphism

Dopamine is a key neurotransmitter of the mesolimbic reward pathway in the human brain, and tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine biosynthesis. Consequently, the gene encoding TH is a strong candidate for involvement in the genetic component of addiction. The importance of this gene in nicotine dependence is supported by many studies showing a link between nicotine administration and TH expression. A functional tetranucleotide repeat polymorphism within intron 1 of the TH gene (HUMTH01-VNTR) has been shown to modify tobacco use in two independent Caucasian samples from the USA and Australia. Using information drawn from an eight-wave Australian population-based longitudinal study of adolescent health, we tested the effect of the HUMTH01-VNTR on nicotine dependence. Comparisons were made between dependent smokers and non-dependent smokers. These data provide further support for a protective association between the K4 allele and dependent smoking (odds ratio 0.54, 95% confidence interval 0.28-1.0). No associations were observed at any of three other common TH polymorphisms (rs6356, rs6357 and HUMTH01-PstI). Including these data, three independent studies, two of which use identical phenotypes, have now identified a protective relationship between the K4 allele of the functional HUMTH01-VNTR polymorphism and high-level smoking.

Estimating individual glomerular volume in the human kidney : clinical perspectives

Background. Measurement of individual glomerular volumes (IGV) has allowed the identification of drivers of glomerular hypertrophy in subjects without overt renal pathology. This study aims to highlight the relevance of IGV measurements with possible clinical implications and determine how many profiles must be measured in order to achieve stable size distribution estimates.

Methods. We re-analysed 2250 IGV estimates obtained using the disector/Cavalieri method in 41 African and 34 Caucasian Americans. Pooled IGV analysis of mean and variance was conducted. Monte-Carlo (Jackknife) simulations determined the effect of the number of sampled glomeruli on mean IGV. Lin’s concordance coefficient (RC), coefficient of variation (CV) and coefficient of error (CE) measured reliability.

Results. IGV mean and variance increased with overweight and hypertensive status. Superficial glomeruli were significantly smaller than juxtamedullary glomeruli in all subjects (P < 0.01), by race (P < 0.05) and in obese individuals (P < 0.01). Subjects with multiple chronic kidney disease (CKD) comorbidities showed significant increases in IGV mean and variability. Overall, mean IGV was particularly reliable with nine or more sampled glomeruli (RC > 0.95, <5% difference in CV and CE). These observations were not affected by a reduced sample size and did not disrupt the inverse linear correlation between mean IGV and estimated total glomerular number.

Conclusions. Multiple comorbidities for CKD are associated with increased IGV mean and variance within subjects, including overweight, obesity and hypertension. Zonal selection and the number of sampled glomeruli do not represent drawbacks for future longitudinal biopsy-based studies of glomerular size and distribution.

Mid-femoral and mid-tibial muscle cross-sectional area as predictors of tibial bone strength in middle-aged and older men

While it is widely acknowledged that bones adapt to the site-specific prevalent loading environment, reasonable ways to estimate skeletal loads are not necessarily available. For long bone shafts, muscles acting to bend the bone may provide a more appropriate surrogate of the loading than muscles expected to cause compressive loads. Thus, the aim of this study was to investigate whether mid-thigh muscle cross-sectional area (CSA) was a better predictor of tibial mid-shaft bone strength than mid-tibia muscle CSA in middle aged and older men. 181 Caucasian men aged 50–79 years (mean±SD; 61±7 years) participated in this study. Mid-femoral and mid-tibial bone traits cortical area , density weighted polar moment of area and muscle CSA [cm²] were assessed with computed tomography. Tibial bone traits were positively associated with both the mid-femur (r=0.44 to 0.46, P<0.001) and the mid-tibia muscle CSA (r=0.35 to 0.37, P<0.001). Multivariate regression analysis, adjusting for age, weight, physical activity and femoral length, indicated that mid-femur muscle CSA predicted tibial mid-shaft bone strength indices better thn mid-tibia muscle CSA. In conclusion, the association between a given skeletal site and functionally adjacent muscles may provide a meaningful probe of the site-specific effect of loading on bone.

A cross-cultural study investigating body features associated with male adolescents' body dissatisfaction in Australia, China, and Malaysia

This study investigated how dissatisfaction with particular aspects of the body was associated with overall body dissatisfaction among male adolescents in Western and Asian cultures. One hundred and six Malaysian Malays, 55 Malaysian Chinese, 195 Chinese from China, and 45 non-Asian Australians aged 12 to 19 years completed a questionnaire assessing dissatisfaction with their overall body and dissatisfaction with varying aspects of their body. Dissatisfaction with the face, height, and hair was positively correlated with overall body dissatisfaction among Malaysian Malays after body mass index, age and dissatisfaction with body areas typically included in measures (weight/shape, upper, middle, and lower body, and muscles) had been controlled for. Dissatisfaction with the face was positively correlated with overall body dissatisfaction among Malaysian Chinese. These findings demonstrate the differences in body focus for males from different cultures and the importance of using assessment measures that address all possible areas of body focus.

Glomerular hypertrophy in subjects with low nephron number: contributions of sex, body size and race

Background. We have shown that low nephron number (Nglom) is a strong determinant of individual glomerular volume (IGV) in male Americans. However, whether the same pattern is present in female Americans remains unclear. The contributions of body surface area (BSA) and race to IGV in the context of Nglom also require further evaluation. Methods. Kidneys without overt renal disease were collected at autopsy in Mississippi, USA. The extremes of female Nglom were used to define high and low N glom for both sexes. Nglom and IGV were estimated by design-based stereology. A total of 24 African and Caucasian American females (n = 12 per race; 6 per Nglom extreme) were included. These subjects were subsequently matched to 24 comparable males by age and Nglom and to 18 additional males by age, Nglom and BSA. Results. IGV average and variance were very similar in female African and Caucasian Americans with high and low Nglom. Males with low Nglom from both races showed greater IGV average and variance than comparable females matched by age and Nglom. These differences in IGV between sexes were not observed in Caucasian Americans with low Nglom that were matched by age, Nglom and BSA. In contrast, glomeruli from African Americans were larger than those from Caucasian Americans, especially in subjects with high Nglom. Conclusions. While female Americans with low Nglom did not show glomerular hypertrophy, comparable males with low Nglom showed marked glomerular hypertrophy that was closely associated with high BSA. Glomerular size in African Americans may be confounded by multiple additional factors. © The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Environmental and genetic determinants of vitamin D insufficiency in 12-month-old infants

We aimed to investigate the relationship between genetic and environmental exposure and vitamin D status at age one, stratified by ethnicity. This study included 563 12-month-old infants in the HealthNuts population-based study. DNA from participants' blood samples was genotyped using Sequenom MassARRAY MALDI-TOF system on 28 single nucleotide polymorphisms (SNPs) in six genes. Using logistic regression, we examined associations between environmental exposure and SNPs in vitamin D pathway and filaggrin genes and vitamin D insufficiency (VDI). VDI, defined as serum 25-hydroxyvitamin D3(25(OH)D3) level ≤50 nmol/L, was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Infants were stratified by ethnicity determined by parent's country of birth. Infants formula fed at 12 months were associated with reduced odds of VDI compared to infants with no current formula use at 12 months. This association differed by ethnicity (P;bsubesub;= 0.01). The odds ratio (OR) of VDI was 0.29 for Caucasian infants (95% CI, 0.18-0.47) and 0.04 for Asian infants (95% CI, 0.006-0.23). Maternal vitamin D supplementation during pregnancy and/or breastfeeding were associated with increased odds of infants being VDI (OR, 2.39; 95% CI, 1.11-5.18 and OR, 2.5; 95% CI, 1.20-5.24 respectively). Presence of a minor allele for any GC SNP (rs17467825, rs1155563, rs2282679, rs3755967, rs4588, rs7041) was associated with increased odds of VDI. Caucasian infants homozygous (AA) for rs4588 had an OR of 2.49 of being associated with VDI (95% CI, 1.19-5.18). In a country without routine infant vitamin D supplementation or food chain fortification, formula use is strongly associated with a reduced risk of VDI regardless of ethnicity. There was borderline significance for an association between filaggrin mutations and VDI. However, polymorphisms in vitamin D pathway related genes were associated with increased likelihood of being VDI in infancy. © 2014 Elsevier B.V. All rights reserved.

Healthy weight regulation and eating disorder prevention in high school students: a universal and targeted web-based intervention

Background: Given the rising rates of obesity in children and adolescents, developing evidence-based weight loss or weight maintenance interventions that can be widely disseminated, well implemented, and are highly scalable is a public health necessity. Such interventions should ensure that adolescents establish healthy weight regulation practices while also reducing eating disorder risk.

Objective: This study describes an online program, StayingFit, which has two tracks for universal and targeted delivery and was designed to enhance healthy living skills, encourage healthy weight regulation, and improve weight/shape concerns among high school adolescents.

Methods: Ninth grade students in two high schools in the San Francisco Bay area and in St Louis were invited to participate. Students who were overweight (body mass index [BMI] >85th percentile) were offered the weight management track of StayingFit; students who were normal weight were offered the healthy habits track. The 12-session program included a monitored discussion group and interactive self-monitoring logs. Measures completed pre- and post-intervention included self-report height and weight, used to calculate BMI percentile for age and sex and standardized BMI (zBMI), Youth Risk Behavior Survey (YRBS) nutrition data, the Weight Concerns Scale, and the Center for Epidemiological Studies Depression Scale.

Results: A total of 336 students provided informed consent and were included in the analyses. The racial breakdown of the sample was as follows: 46.7% (157/336) multiracial/other, 31.0% (104/336) Caucasian, 16.7% (56/336) African American, and 5.7% (19/336) did not specify; 43.5% (146/336) of students identified as Hispanic/Latino. BMI percentile and zBMI significantly decreased among students in the weight management track. BMI percentile and zBMI did not significantly change among students in the healthy habits track, demonstrating that these students maintained their weight. Weight/shape concerns significantly decreased among participants in both tracks who had elevated weight/shape concerns at baseline. Fruit and vegetable consumption increased for both tracks. Physical activity increased among participants in the weight management track, while soda consumption and television time decreased.

Conclusions: Results suggest that an Internet-based, universally delivered, targeted intervention may support healthy weight regulation, improve weight/shape concerns among participants with eating disorders risk, and increase physical activity in high school students. Tailored content and interactive features to encourage behavior change may lead to sustainable improvements in adolescent health.

Migratory implications for coronary heart disease risk prevention in Asian Indians: Evidence from the leading health indicators.

OBJECTIVEctives of this descriptive comparative study were to (1) review data obtained from the World Health Organisation Statistical Information System (WHOSIS) database relating to the prevalence of risk factors for coronary heart disease (CHD) among Indians and Australians and (2) compare these data with published epidemiological studies of CHD riskfactors in adult migrant Asian Indians to provide a comprehensive and comparable assessment of risk factors relating to CHD and the mortality attributable to these risk factors. Design: ThDESIGNdy was undertaken using a database search and integrative review methodology. Data were obtained for comparison of CHD risk factors between Indians and Australians using the WHOSIS database. For the integrative review the MEDLINE, CINAHL, EMBASE, and Cochrane databases were searched using the keywords 'Migrants', 'Asian Indian', 'India', 'Migration', 'Immigration', 'Risk factors', and coronary heart disease. Two reviewers independently assessed the eligibility of the studies for inclusion in the review, the methodological quality and extracted details of eligible studies. Results from the integrative review on CHD risk factors in Asian Indians are presented in a narrative format, along with results from the WHOSIS database. Results: TRESULTSadjusted mortality for CHD was four times higher in migrant Asian Indians when compared to both the native population of the host country and migrants from other countries. Similarly when compared to migrants from other countries migrant Asian Indians had the highest prevalence of overweight individuals. Prevalence rates for hypercholesterolemia were up to 18.5 % among mgrant Asian Indians and migrant Asian Indian women had a higher prevalence of hypertriglyceridaemia compared to Caucasian females. Migrant Asian Indians also had a higher incidence of hypertension and upto 71 % of migrnt Asian Indian men did not meet current guidelines for participation in physical activity. Ethnic-specific prevalence of diabetes ranged from 6-7% among the normal weight to 19-33% among the obese migrant Asian Indians compared with non-Hispanic whites. ConclusionCONCLUSIONAsian Indians have an increased risk of CHD. Culturally sensitive strategies that recognise the effects of migration and extend beyond the health sector should be developed to target lifestyle changes in this high risk population.

Profile of European adults interested in internet-based personalised nutrition: the Food4Me study

PURPOSE: Personalised interventions may have greater potential for reducing the global burden of non-communicable diseases and for promoting better health and well-being across the lifespan than the conventional "one size fits all" approach. However, the characteristics of individuals interested in personalised nutrition (PN) are unclear. Therefore, the aim of this study was to describe the characteristics of European adults interested in taking part in an internet-based PN study. METHODS: Individuals from seven European countries (UK, Ireland, Germany, The Netherlands, Spain, Greece and Poland) were invited to participate in the study via the Food4Me website ( http://www.food4me.org ). Two screening questionnaires were used to collect data on socio-demographic, anthropometric and health-related characteristics as well as dietary intakes. RESULTS: A total of 5662 individuals expressed an interest in the study (mean age 40 ± 12.7; range 15-87 years). Of these, 65 % were female and 97 % were Caucasian. Overall, 13 % were smokers and 47 % reported the presence of a clinically diagnosed disease. Furthermore, 47 % were overweight or obese and 35 % were sedentary during leisure time. Assessment of dietary intakes showed that 54 % of individuals reported consuming at least 5 portions of fruit and vegetables per day, 46 % consumed more than 3 servings of wholegrains and 37 % limited their salt intake to <5.75 g per day. CONCLUSIONS: Our data indicate that individuals volunteering to participate in an internet-based PN study are broadly representative of the European adult population, most of whom had adequate nutrient intakes but could benefit from improved dietary choices and greater physical activity. Future use of internet-based PN approaches is thus relevant to a wide target audience.