Total and appendicular lean mass reference ranges for Australian men and women: the Geelong osteoporosis study.

The aim of this study was to develop reference ranges for total and appendicular lean mass measured using dual-energy X-ray absorptiometry (DXA) from a randomly selected population-based sample of men and women residing in southeastern Australia. Men (n = 1,411) and women (n = 960) aged 20-93 years, enrolled in the Geelong Osteoporosis Study, were randomly selected from the Barwon Statistical Division using the electoral roll as a sampling frame in 2001-2006 (67 % participation) and 1993-1997 (77 % participation), respectively. Using DXA (Lunar DPX-L or Prodigy Pro) at baseline for men and at the 10-year follow-up for women (2004-2008), total and appendicular lean mass were measured. Means and standard deviations for each lean mass measure (absolute and relative to height squared) were generated for each age decade, and cutpoints equivalent to T scores of -2.0 and -1.0 were calculated using data from young adult men and women aged 20-39 years. Young adult reference data were derived from 374 men and 308 women. Cutpoints for relative appendicular lean mass equal to T scores of -2.0 and -1.0 were 6.94 and 7.87 kg/m(2) for men and 5.30 and 6.07 kg/m(2) for women. The proportions of men and women aged ≥80 years with a T score less than -2.0 were 16.0 and 6.2 %, respectively. These reference ranges may be useful for identifying lean mass deficits in the assessment of muscle wasting and sarcopenia.

Musculoskeletal deterioration in men accompanies increases in body fat.

OBJECTIVE: To examine body fat and musculoskeletal changes in men over 5 years. METHODS: Body composition was evaluated for men in the Geelong Osteoporosis Study using whole body dual energy X-ray absorptiometry (DXA) during two time-periods. DXA was performed for 1329 men (25-96 years) during 2001-2006 and for 900 men (25-98 years), 2006-2011. The masses of fat, lean, and bone were expressed relative to the square of height (kg/m2). Each compartment was also expressed as a percentage relative to body weight (%fat, %lean, %bone). RESULTS: Mean BMI increased from 26.9 kg/m2 in 2001-2006, to 27.2 kg/m2 in 2006-2011 (P = 0.04). Mean fat mass increased by 9.0% from 6.98 kg/m2 (95% CI 6.84-7.11) in 2001-2006, to 7.60 kg/m2 (7.44-7.77) in 2006-2011 (P < 0.001); mean lean mass decreased by 0.9%, from 18.92 kg/m2 (18.83-19.01) to 18.75 kg/m2 (18.64-18.86) (P = 0.02), and mean bone mass decreased 1.6% from 1.041 kg/m2 (1.034-1.047), to 1.024 kg/m2 (1.016-1.032). Mean %fat increased from 23.4% to 25.2%, mean %lean decreased from 72.6% to 70.9% and mean %bone decreased from 4.0% to 3.9% (all P < 0.05). CONCLUSIONS: An increase in BMI, which reflects a substantial increase in body fat mass and declines in both lean and bone mass was reported. This may have implications for future development of bone fragility, sarcopenia, and sarcopenic obesity.

Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation.

OBJECTIVES: The peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart failure but has not been assessed in Fontan subjects. We sought to investigate whether adults with the Fontan circulation exhibit reduced skeletal muscle mass and/or metabolic abnormalities. DESIGN AND PATIENTS: Sixteen New York Heart Association Class I/II Fontan adults (30±2 years) underwent cardiopulmonary exercise testing and lean mass quantification with dual x-ray absorptiometry (DXA); eight had calf muscle (31)P magnetic resonance spectroscopy as did eight healthy age-matched and sex-matched controls. DXA results were compared with Australian reference data. SETTING: Single tertiary referral centre. RESULTS: Peak VO2 was 1.9±0.1 L/min (66±3% of predicted values). Skeletal muscle mass assessed by relative appendicular lean mass index was significantly reduced compared with age-matched and sex-matched reference values (Z-score -1.46±0.22, p<0.0001). Low skeletal muscle mass correlated with poorer VO2 max (r=0.67, p=0.004). Overall, skeletal muscle mass T-score (derived from comparison with young normal reference mean) was -1.47±0.21; 4/16 Fontan subjects had sarcopenic range muscle wasting (T-score <-2.0) and 9/16 had less marked, but clinically significant wasting (T-score <-1.0 but ≥-2.0). Muscle aerobic capacity, measured by the rate constant (k) of postexercise phosphocreatine resynthesis, was significantly impaired in Fontan adults versus controls (1.48±0.13 vs 2.40±0.33 min(-1), p=0.02). CONCLUSIONS: Fontan adults have reduced skeletal muscle mass and intrinsic muscle metabolic abnormalities.

Sex-differences in reasons for non-participation at recruitment: Geelong Osteoporosis Study.

BACKGROUND: Understanding reasons for non-participation in health studies can help guide recruitment strategies and inform researchers about potential sources of bias in their study sample. Whilst there is a paucity of literature regarding this issue, it remains highly plausible that men and women may have varied reasons for declining an invitation to participate in research. We aimed to investigate sex-differences in the reasons for non-participation at baseline of the Geelong Osteoporosis Study (GOS). METHODS: The GOS, a prospective cohort study, randomly recruited men and women aged 20 years and over from a region in south-eastern Australia using Commonwealth electoral rolls (2001-06 and 1993-97, respectively). Reasons for non-participation (n=1,200) were documented during the two recruitment periods. We used the Pearson's chi squared test to explore differences in the reasons for non-participation between men and women. RESULTS: Non-participation in the male cohort was greater than in the female cohort (32.9% vs. 22.9%; p<0.001). Overall, there were sex-differences in the reasons provided for non-participation (p<0.001); apparent differences related to time constraints (men 26.3% vs. women 10.4%), frailty/inability to cope with or understand the study (men 18.7% vs. women 30.6%), and reluctance over medical testing (men 1.1% vs women 9.9%). No sex-differences were observed for non-participation related to personal reason/disinterest, and language- or travel-related reasons. CONCLUSIONS: Improving participation rates in epidemiological studies may require different recruitment strategies for men and women in order to address sex-specific concerns about participating in research.

Social determinants of bone densitometry uptake for osteoporosis risk in patients aged 50yr and older: a systematic review.

The World Health Organization identifies that osteoporosis is one of the leading health problems in the Western world. An increased risk of fragility fracture is observed in more socially disadvantaged individuals in most Western countries. Dual-energy X-ray absorptiometry (DXA) is currently the procedure of choice to diagnose osteoporosis and assess fracture risk. We systematically reviewed the literature regarding social determinants of DXA utilization for osteoporosis detection in patients aged 50yr and older using a computer-aided search of MEDLINE, EMBASE, CINAHL, and PsychINFO from January 1994 to December 2010. Five cross-sectional studies, incorporating 16 separate analyses, were identified for inclusion in this review. The best evidence analysis identified limited evidence for a positive association between either income or education with DXA utilization; furthermore, the best evidence analysis found no evidence for an association between either marital status or working status and DXA utilization. Further research is required to identify whether a relationship exists and elucidate reasons for disparities in DXA utilization between different social groups, such as choice and referral processes, as a necessary precursor in identifying modifiable determinants and appropriate strategies to promote preventive screening to identify fracture risk.

PPAR gamma ligands, 15-deoxy-delta12,14-prostaglandin J2 and rosiglitazone regulate human cultured airway smooth muscle proliferation through different mechanisms.

The influence of two peroxisome proliferator-activated receptor gamma (PPARgamma) ligands, a thiazolidinedione, rosiglitazone (RG) and the prostaglandin D2 metabolite 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) on the proliferation of human cultured airway smooth muscle (HASM) was examined. The increases in HASM cell number in response to basic fibroblast growth factor (bFGF, 300 pm) or thrombin (0.3 U ml-1) were significantly inhibited by either RG (1-10 microM) or 15d-PGJ2 (1-10 microM). The effects of RG, but not 15d-PGJ2, were reversed by the selective PPARgamma antagonist GW9662 (1 microM). Neither RG nor 15d-PGJ2 (10 microM) decreased cell viability, or induced apoptosis, suggesting that the regulation of cell number was due to inhibition of proliferation, rather than increased cell death. Flow-cytometric analysis of HASM cell cycle distribution 24 h after bFGF addition showed that RG prevented the progression of cells from G1 to S phase. In contrast, 15d-PGJ2 caused an increase in the proportion of cells in S phase, and a decrease in G2/M, compared to bFGF alone. Neither RG nor 15d-PGJ2 inhibited ERK phosphorylation measured 6 h post mitogen addition. The bFGF-mediated increase in cyclin D1 protein levels after 8 h was reduced in the presence of 15d-PGJ2, but not RG. Although both RG and 15d-PGJ2 can inhibit proliferation of HASM irrespective of the mitogen used, only the antiproliferative effects of RG appear to be PPARgamma-dependent. The different antimitogenic mechanisms of 15d-PGJ2 and synthetic ligands for PPARgamma may be exploited to optimise the potential for these compounds to inhibit airway remodelling in asthma. British Journal of Pharmacology (2004) 141, 517-525. doi:10.1038/sj.bjp.0705630