Circulating periostin levels do not differ between postmenopausal women with normal and low bone mass and are not affected by zoledronic acid treatment.

Periostin is a secreted extracellular matrix protein preferentially expressed in bone by osteocytes and periosteal osteoblasts. Reduced periostin expression may affect osteoblast differentiation and collagen type I synthesis and predispose to osteoporosis and increased fracture risk. We aimed to evaluate circulating periostin levels in postmenopausal women with low bone mass, their possible correlations with clinical and laboratory parameters, as well as the 3-month effect of zoledronic acid. Serum samples for periostin, 25-hydroxyvitamin D, parathyroid hormone (PTH), C-terminal telopeptide of type I collagen (CTx), and total alkaline phosphatase (tALP) were obtained from 46 postmenopausal women with low bone mass at baseline and 3 months after zoledronic acid infusion and from 30 age-matched, postmenopausal controls with normal bone mass at baseline. There was no difference in periostin levels between women with normal and low bone mass (250±15 vs. 272±14 ng/ml, respectively; p=0.279). Periostin remained essentially unchanged after zoledronic acid infusion (262±18 ng/ml; p=0.130). Serum periostin levels at baseline were not affected by previous bisphosphonate treatment, and were correlated only to tALP (rs=0.351; p=0.018). In multiple linear regression analysis, tALP (B=3.17; 95% CI=0.59-5.79; p=0.018) was associated with serum periostin levels at baseline, independently from previous anti-osteoporotic treatment, age, body mass index, and 25-hydroxyvitamin D. In conclusion, serum periostin levels do not differ between postmenopausal women with normal and low bone mass and are not affected by zoledronic acid treatment. Women with higher tALP have independently higher periostin levels.

The reproducibility of hemodynamic, electrocardiographic, and gas exchange data during treadmill exercise in patients with stable angina pectoris.

Fourteen male patients with exercise test-induced angina and ST-segment depression underwent treadmill testing on three consecutive days to evaluate the reproducibility of certain treadmill variables. Computerized ST-segment analysis and expired gas analysis, including anaerobic threshold, were evaluated for reproducibility using an intra-class correlation coefficient analysis. Measured oxygen uptake at peak exercise displayed better reproducibility than total treadmill time, the onset of angina, and the gas exchange anaerobic threshold (ATGE). The double product, heart rate, and ST-segment displacement in lead X were found to be reproducible at peak exercise, the onset of angina, and the ATGE. The incorporation of gas exchange analysis can provide accurate physiologic determinants of exercise capacity in patients with angina pectoris. In addition, noninvasive estimates of myocardial oxygen demand and ischemia can be reproducibly determined. These findings have important implications for the design of studies evaluating the effects of an intervention on angina pectoris.