Hypercorticism blunts circadian variations of osteocalcin regardless of nutritional status.

Anorexia nervosa (AN) and Cushing's syndrome (CS) are both responsible for osteoporosis. The mechanisms leading to osteoporosis in AN include hypogonadism, nutritional depletion, and in some cases hypercorticism. Osteocalcin circulating level is a serum marker of osteoblastic activity that follows a circadian rhythm (OCR).

Cell cycling determines integrin-mediated adhesion in osteoblastic ROS 17/2.8 cells exposed to space-related conditions.

Six days of microgravity (Bion10 mission) induced dramatic shape changes in ROS 17/2.8 osteoblasts (7). During the Foton 11 and 12 space flights, we studied the kinetics (0-4 days) of ROS 17/2.

Space flight is associated with rapid decreases of undercarboxylated osteocalcin and increases of markers of bone resorption without changes in their circadian variation: observations in two cosmonauts.

Background: Microgravity induces bone loss by mechanism(s) that remain largely unknown.

Methods: We measured biochemical markers related to bone remodeling in two cosmonauts before, during, and after 21- and 180-day space flights, respectively.

Results: During both flights, type I procollagen propeptide and bone alkaline phosphatase decreased as early as 8 days after launch.

Weight gain reverses bone turnover and restores circadian variation of bone resorption in anorexic patients.

Objective: The present study was conducted in order to describe the variations and circadian rhythm of biochemical markers of bone remodelling at baseline and after weight gain in patients with anorexia nervosa (AN).

Subjects: We studied 9 women (mean age 21 years, range: 16-30) with established AN who remained amenorrhoeic during the study and with a low body mass index (BMI) after refeeding and 6 female controls (mean age 20 years, range, 18-24 and BMI: 20.6 +/- 1.

Effects of static or dynamic mechanical stresses on osteoblast phenotype expression in three-dimensional contractile collagen gels.

Studies performed at tissular (three-dimensional, 3-D) or cellular (two-dimensional, 2-D) levels showed that the loading pattern plays a crucial role in the osteoblastic physiology. In this study, we attempted to investigate the response of a 3-D osteoblastic culture submitted to either no external stress or static or dynamic stresses. Rat osteosarcoma cells (ROS 17/2.