Engineering topics

Morukov, B. V.

Publications and source records attributed to Morukov, B. V..

4 records

NASA NTRS2001

Calcium Kinetics During Long-Duration Space Flight

Bone loss represents one of the most significant effects of space flight on the human body. Understanding the mechanisms underlying this loss is critical for maintaining crew health and safety during and after flight. This investigation documents the changes in bone metabolism and calcium kinetics during and after space flight. We previously reported calcium studies on three subjects during and after a 115-d stay on the Russian space station Mir. We report here data on an additional three subjects, whose stays on Mir were approximately 4 (n=l) and 6 (n=2) mos. Previously published data are included for comparison.

Smith, Scott M.↗

NASA NTRS1999

Calcium metabolism before, during, and after a 3-mo spaceflight: kinetic and biochemical changes

The loss of bone during spaceflight is considered a physiological obstacle for the exploration of other planets. This report of calcium metabolism before, during, and after long-duration spaceflight extends results from Skylab missions in the 1970s. Biochemical and endocrine indexes of calcium and bone metabolism were measured together with calcium absorption, excretion, and bone turnover using stable isotopes. Studies were conducted before, during, and after flight in three male subjects. Subjects varied in physical activity, yet all lost weight during flight. During flight, calcium intake and absorption decreased up to 50%, urinary calcium excretion increased up to 50%, and bone resorption (determined by kinetics or bone markers) increased by over 50%. Osteocalcin and bone-specific alkaline phosphatase, markers of bone formation, increased after flight. Subjects lost approximately 250 mg bone calcium per day during flight and regained bone calcium at a slower rate of approximately 100 mg/day for up to 3 mo after landing. Further studies are required to determine the time course of changes in calcium homeostasis during flight to develop and assess countermeasures against flight-induced bone loss.

NASA Discipline Regulatory Physiology↗

NASA NTRS1988

Regulation of calcium metabolism during prolonged antiorthostatic hypokinesia

Characteristics of the regulation of calcium exchange in healthy persons exposed to 182 days of antiorthostatic hypokinesia are investigated. Total calcium concentrations, ionized calcium activities and parathyroid hormone concentrations in blood serum were determined, before, during, and up to 15 days after a 182-day period of strict bed rest at a head down tilt of 4 deg; and tests of blood urine responses to a calcium lactate stress were performed to study the role of the kidneys. An increase in calcium ion activity is observed during the period of hypokinesia, while total calcium concentrations changed to a lesser degree. Plasma parathyroid hormone levels are found to significantly exceed background levels during hypokinesia and in the recovery period immediately following. Finally, the increase in calcium excretion in the urine during prolonged limitations of muscular activity is found to be connected with both an enhancement of calcium filtration and a decrease in its reabsorption in the kidneys, possibly due to changes in hormonal regulation.

Grigoryev, A. I.↗

NASA NTRS1988

Use of diphosphonates to correct disorders in calcium metabolism and mineral composition of bone tissue with 60-day hypokinesia in rats

Compounds of the diphosphonate group suppress bone resorption and bone tissue metabolism, from which it was assumed that they can be used for the prevention of osteoporosis and disorders of calcium homeostasis in humans during space flight. Two compounds of this group were used for preventive purposes in 60 day hypokinesia in rats. The results showed that diphosphonates have a marked effect on calcium metabolism and the condition of the bone tissues under conditions of long term hypokinesia: they reduce the content of ionized calcium in blood, delay the loss of calcium and phosphorus by the bone tissue, and to a considerable degree prevent reduction of bone density. This confirms the possibility of using compounds of this group for correcting and preventing changes of bone tissue and mineral metabolism during long term hypokinesia.

Morukov, B. V.↗