Accuracy of body mass index in volunteer firefighters.

BACKGROUND: Obesity is prevalent among career firefighters and may contribute to heart attacks, a leading cause of on-duty fatalities. The US National Fire Protection Association estimates that 800 000 of 1.1 million firefighters are volunteers. Body mass index (BMI) is commonly used to assess obesity, but little is known about its accuracy in volunteer firefighters, in whom muscle mass may be higher, given firefighting's physical demands, reducing its accuracy in identifying obesity. AIMS: To evaluate the accuracy of BMI in identifying obese volunteer firefighters. METHODS: Height, weight and body composition were measured in 73 male volunteer firefighters (mean age 40±12). The proportions with BMI ≥ 25kg/m(2), ≥30kg/ m(2) and percent fat ≤ 20th percentile were determined. Using the age-specific 20th percentile for percent fat (Cooper Clinic) as the criterion for being over-fat, the accuracy of BMI was assessed using sensitivity and specificity calculations. RESULTS: The means ± standard deviation of BMI and percent fat were 32±6 and 25±5, respectively. The proportions with a BMI ≥ 25 and ≥30 were 90% and 60%, respectively. Fifty-one percent had a percent fat ≤ 20th percentile. The measure BMI ≥ 25 had a perfect sensitivity (1.0) and low specificity (0.19) and BMI ≥ 30 had a high sensitivity (0.89) and moderate specificity (0.69). CONCLUSIONS: Although BMI ≥ 30 accurately predicted being over-fat, it misclassified large and lean firefighters. Although BMI should be used cautiously, it can identify over-fat firefighters at risk of cardiovascular disease, and its measurement is cost-effective and simple.

CD73/5'-ecto-nucleotidase acts as a regulatory factor in osteo-/chondrogenic differentiation of mechanically stimulated mesenchymal stromal cells.

Bone regeneration is influenced by mesenchymal stromal cells (MSCs) and mechanical conditions. How healing outcome and mechanical stability are linked on the cellular level, however, remains elusive. Cyclic-compressive loading of MSCs affects the expression of molecules involved in angiogenesis and matrix assembly, but also reduces the expression of CD73, an ecto-5'-nucleotidase, which plays a crucial role in extracellular adenosine generation. Although, for almost 20 years, CD73 has been a major cell surface marker defining MSCs, little is known about its function in these cells. Therefore, the aim of this study was to determine the putative involvement of CD73 in MSC differentiation after cyclic-compressive loading. After cultivation in appropriate differentiation media, chondrogenic differentiation ability was significantly increased in loaded MSCs, hence following current models. Through treatment with the CD73 inhibitor adenosine 5'-(α, ß-methylene) diphosphate, chondrogenic matrix deposition was further increased; in contrast, mineral matrix deposition and expression of osteogenic markers was reduced. One major signal transduction pathway, which is activated via CD73-mediated adenosine, is the adenosine receptor pathway. Thus, the adenosine receptor expression pattern was investigated. MSCs expressed the four known adenosine receptors at the mRNA level. After mechanical stimulation of MSCs, Adora2a was down-regulated. These data point towards a role of CD73 in MSC differentiation possibly via A2AR signalling, which is mutually regulated with CD73. In conclusion, the findings of this study suggest that CD73 is another regulatory factor in osteo-/chondrogenic differentiation of MSCs and may provide a - thus far underestimated - therapeutic target to guide bone regeneration.