Manfred Heer

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Osteopenia and osteoporosis are complications of adolescent anorexia nervosa (AN) and may result in a permanent deficit of bone mass in adulthood. It is still unclear if a complete catch-up in bone mineral density (BMD) is possible after weight rehabilitation in AN. Methods. We investigated bone formation (bAP, PICP), bone resorption (CTX) and BMD (lumbar(More)
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(More)
Previously it was shown that hyperleptinemia ensues from the therapeutically induced weight gain in patients with anorexia nervosa (AN). However, not all studies have been able to confirm this finding. To further investigate leptin secretion during weight gain in AN and potential functional implications serum leptin levels, body mass index (BMI),% body fat,(More)
Several hormonal systems participating in body fluid and electrolyte homeostasis were investigated in six healthy volunteers in a supine body position during a period of 9 days and nights. Under strictly controlled conditions, striking circadian rhythms were observed for plasma levels of vasopressin, renin, aldosterone, guanosine 3',5'-cyclic monophosphate,(More)
In the present study the response to acute saline loading was investigated. During a 24-day study period six male subjects followed a standardized diet including a daily intake of 40 ml water and 125 mg NaCl per kg body weight. Before, during, and after a ten-day period of 6 degrees head down tilt (HDT) each volunteer received an intravenous 0.9% saline(More)
It has repeatedly been shown that high serum leptin levels at target weight ensue from therapeutically induced weight gain in patients with anorexia nervosa (AN). It was hypothesized that elevated leptin levels may be an important factor underlying the difficulties of maintaining the target-weight in AN patients after re-feeding. The aim of this study was(More)
Results from space have been unexpected and not predictable from the results of ground-based simulations. Therefore, the concept of how weightlessness and gravity modulates the regulation of body fluids must be revised and a new simulation model developed. The main questions to ask in the future are the following: Does weightlessness induce a diuresis and(More)
BACKGROUND The associations between nitrogen metabolism and bone turnover during bed rest are still not completely understood. METHODS We measured nitrogen balance (nitrogen intake minus urinary nitrogen excretion) and biochemical metabolic markers of calcium and bone turnover in six males before head-down tilt bed rest (baseline), during 2, 10, and 14(More)
Similar to the response to central hypervolemic conditions on Earth, the shift of blood volume from the legs to the upper part of the body in astronauts entering micro-gravity should, in accordance with the Henry-Gauer mechanism, mediate diuresis and natriuresis. However, fluid balance and kidney function experiments during various space missions resulted(More)
We tested the hypothesis that adaptation to microgravity, simulated by a 10-day period of head-down tilt (HDT), alters the responses to an intravenous fluid load by causing a larger fraction of the infused volume to be retained and magnifying the acute hemodynamic effects. HDT caused a significant (p less than 0.01) decrease in blood volume (-0.72 liters)(More)