Longitudinal analysis of the relationship between physical function and mortality in ambulatory older men

Background. Low physical performance is an important characteristic of frailty and sarcopenia. In this study, we wanted to assess and compare the predictive value of physical function measurements for all-cause mortality in older men. Methods. Data are from a longitudinal study of a population-based sample of 352 ambulatory older men aged 71 to 86 at study baseline. The Rapid disability rating scale-2, 36-Item short form health survey, Hand grip strength, Five times sit-to-stand test, Standing balance, and Timed Up and Go test were determined at baseline. Associations with all-cause mortality were assessed using Cox proportional hazard analyses. Age, BMI, smoking status, education, physical activity, and cognitive status were included as confounders. Follow-up exceeded 15 years. Results. The mean age of participants was 76 ± 4.2 years. Average follow-up duration was 184 ± 2 months. Seventy-eight percent (273) of the 352 men died during follow-up, with a median survival time of 110 months. All examined physical function measurements were associated with all-cause mortality. The Timed Up and Go test was the best predictor (adjusted HR per SD increase = 1.58, 95% CI = 1.40-1.79, P < 0.001) for global mortality. Conclusions. Our findings demonstrate that physical function measurements are important in the evaluation of older persons. We encourage the use of the Timed Up and Go test as a reliable, quick and feasible screening tool in clinical settings

Genetic variations in the androgen receptor are associated with steroid concentrations and anthropometrics but not with muscle mass in healthy young men

OBJECTIVE: The relationship between serum testosterone (T) levels, muscle mass and muscle force in eugonadal men is incompletely understood. As polymorphisms in the androgen receptor (AR) gene cause differences in androgen sensitivity, no straightforward correlation can be observed between the interindividual variation in T levels and different phenotypes. Therefore, we aim to investigate the relationship between genetic variations in the AR, circulating androgens and muscle mass and function in young healthy male siblings. DESIGN: 677 men (25-45 years) were recruited in a cross-sectional, population-based sibling pair study. METHODS: Relations between genetic variation in the AR gene (CAGn, GGNn, SNPs), sex steroid levels (by LC-MS/MS), body composition (by DXA), muscle cross-sectional area (CSA) (by pQCT), muscle force (isokinetic peak torque, grip strength) and anthropometrics were studied using linear mixed-effect modelling. RESULTS: Muscle mass and force were highly heritable and related to age, physical activity, body composition and anthropometrics. Total T (TT) and free T (FT) levels were positively related to muscle CSA, whereas estradiol (E2) and free E2 (FE2) concentrations were negatively associated with muscle force. Subjects with longer CAG repeat length had higher circulating TT, FT, and higher E2 and FE2 concentrations. Weak associations with TT and FT were found for the rs5965433 and rs5919392 SNP in the AR, whereas no association between GGN repeat polymorphism and T concentrations were found. Arm span and 2D:4D finger length ratio were inversely associated, whereas muscle mass and force were not associated with the number of CAG repeats. CONCLUSIONS: Age, physical activity, body composition, sex steroid levels and anthropometrics are determinants of muscle mass and function in young men. Although the number of CAG repeats of the AR are related to sex steroid levels and anthropometrics, we have no evidence that these variations in the AR gene also affect muscle mass or function

Thyroid hormone levels within reference range are associated with heart rate, cardiac structure, and function in middle-aged men and women

Background: Triiodothyronine (T3) has many effects on the heart, and marked changes in cardiac function and structure occur in patients with (subclinical) thyroid disease. We investigated whether between-subject variation in thyroid hormone levels within the euthyroid range is also associated with heart rate and echocardiographic heart function and structure. Methods: Subjects were selected from the Asklepios study (n=2524), a population-representative random sample of patients aged between 35 and 55 years, free from overt cardiovascular disease at baseline. Analyses were restricted to 2078 subjects (1013 women and 1065 men), not using antihypertensive or thyroid medication nor having antithyroperoxidase antibody levels above clinical cut-off or thyrotropin (TSH) levels outside the reference range. All subjects were phenotyped in-depth and underwent comprehensive echocardiography, including diastolic evaluation. Thyroid function parameters were determined by automated electrochemiluminescence. Results: Heart rate was robustly positively associated with (quartiles of) free T3 (FT3) and T3, both in subjects with TSH levels within reference (0.27-4.2 μU/L) and in narrow TSH range (0.5-2.5 μU/L; p<0.0001). FT3 and T3 were negatively associated with left ventricular (LV) end-diastolic volume but positively associated with relative wall thickness. Total T3 (TT3) was associated with enhanced ventricular contraction (as assessed by tissue Doppler imaging). Free thyroxine, FT3, and TT3 were positively associated with late ventricular filling, and TT3 was associated with early ventricular filling. Conclusion: We have demonstrated a strong positive association between thyroid hormone levels within the euthyroid range and heart rate, and more subtle effects on cardiac function and structure. More specifically, we suggest a smaller LV cavity size (with increased relative wall thickness), an enhanced atrial and ventricular contraction, and LV relaxation with higher circulating thyroid hormones. These results illustrate that variation in thyroid hormone levels, even within the reference range, exerts effects on the heart

Triiodothyronine and free thyroxine levels are differentially associated with metabolic profile and adiposity-related cardiovascular risk markers in euthyroid middle-aged subjects

Background: We previously showed that in healthy young men a less favorable body composition is associated with higher FT3 levels within the euthyroid range. Besides, a higher FT3-to-FT4 ratio has been related to a less favorable metabolic phenotype and more placental growth in pregnant women. In the present study, we therefore investigated whether serum TSH, thyroid hormone levels and the FT3-to-FT4 ratio are associated with metabolic and adiposity-related cardiovascular risk markers in a healthy population of middle-aged euthyroid men and women. Methods: Thyroid parameters were measured in 2524 generally healthy subjects from the Asklepios study (35-55yrs, mean age 46 years). Analyses were restricted to 2315 subjects (1138 women and 1177 men), not using thyroid medication, not having anti-TPO levels above clinical cut-off values nor TSH levels outside the reference range (0.27-4.2 mU/L). Twenty-seven percent of the women and 47.5% of the men were overweight, while 13% of women and 17% of men were obese. Twenty percent of the subjects were active smokers. Serum thyroid function parameters were determined by electrochemiluminescence. Results: (F) T3 and the FT3-to-FT4 ratio were positively related to BMI, waist circumference and components of the metabolic syndrome, i.e. triglycerides, systolic and diastolic blood pressure and fasting plasma glucose, and negatively with HDL-cholesterol levels, whereas FT4 was negatively associated to BMI, waist circumference and triglycerides (all p-values <0.001). TSH related positively to total cholesterol levels (p<0.01), triglycerides and to systolic and diastolic blood pressure (all p<0.001). The FT3-to-FT4 ratio was further positively associated to the adiposity-related inflammation markers interleukin-6 (IL6) and high-sensitive CRP (hs-CRP) and to pulse wave velocity. All associations were adjusted for sex, age, height and smoking and most associations persisted after additional adjustment for weight or waist circumference. Conclusion: In healthy euthyroid middle-aged men and women, higher (F) T3 levels, lower FT4 levels and thus a higher FT3-to-FT4 ratio are consistently associated with various markers of unfavorable metabolic profile and cardiovascular risk

Heisenberg model in a random field: phase diagram and tricritical behavior

By using the differential operator technique and the effective field theory scheme we study the tricritical behavior of Heisenberg classical model of spin-1/2 in a random field. The phase diagram in the T-h plane on a square and simple cubic lattice for a cluster with two spins is obtained when the random field is bimodal distributed.Comment: 10 pages, 1 figur

Association between insulin resistance, lean mass and muscle torque/force in proximal versus distal body parts in healthy young men

Objectives:The purpose of this study was to investigate whether there is already an association of insulin resistance (IR) with muscle mass and –force/torque in an adult population and whether this relationship is the same in distal and proximal body parts. Methods: 358 Healthy young men were divided into a more insulin sensitive (MIS) (n=89) and a less insulin sensitive (LIS) group (n=89), respectively using lower and upper quartiles of HOMA-IR index (Homeostasis Model Assessment of IR). Muscle force/torque and lean mass, were compared between the two groups. Results: LIS subjects had higher absolute thigh lean mass, but not higher thigh muscle torque, resulting in a lower torque per kg muscle. In upper arm, lean mass was higher in LIS subjects, but also absolute muscle torque resulted higher. For handgrip force, the LIS and MIS group had similar results, despite a trend towards higher forearm lean mass in LIS subjects. Lean mass % of total lean mass is lower in LIS subjects in more distal body parts. Conclusions:Already in a young healthy population, IR seems to be associated with lower force/torque per muscle mass and lower lean mass % of total lean mass predominantly in more distal body parts

Determinants of vitamin D status in young children : results from the Belgian arm of the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) study

Objective: To describe the vitamin D status of Belgian children and examine the influence of non-nutritional determinants, in particular of anthropometric variables. Design: Cross-sectional data of Belgian participants of the EU 6th Framework Programme IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) Study. Setting: 25-Hydroxyvitamin D (25(OH)D) was measured using RIA. Vitamin D status was categorized as deficient (= 75 nmol/1). Anthropometric measurements included height, weight, waist and hip circumferences and triceps and subscapular skinfold thicknesses. Subjects: Children (n 357) aged 4-11 years. Results: Serum 25(OH)D) ranged from 13.6 to 123.5 nmol/1 (mean 47.2 (SD 14.6) nmol/1); with 5% deficient, 53% insufficient, 40% sufficient and 2% optimal. No significant differences were found by age and gender. Significant differences in 25(OH)D were observed for month of sampling (P < 0.001), number of hours playing outside per week (r = 0.140), weight (r = -0.121), triceps (r = -0.112) and subscapular (r = -0.119) skinfold thickness, sum of two skinfold thicknesses (r = -0.125) and waist circumference (r = -0.108). Linear regression analysis of 25(OH)D adjusted for age, month of sampling and hours playing outside per week suggested that (i) weight, (ii) BMI Z-score, (iii) waist circumference and (iv) triceps and subscapular skinfold thickness (as well as the sum of both) independently influenced 25(OH)D. Conclusions: The majority of Belgian children had a suboptimal vitamin D status, with more than half having an insufficient status in winter and spring. Month of the year, weekly number of hours playing outside and body composition - both central and abdominal obesity - were identified as important determinants of vitamin D status in Belgian children