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At least 667 records · Page 37

Vise to hold bones or other irregular objects

Vise with stationary vee-shaped jaw and segmented notched jaw for holding irregular shaped objects is described. Operation of the device and specific application to holding bones are explained. Diagram of equipment is provided.

Dowell, R. H.↗

Bone demineralization

Crew members of the Gemini 4, Gemini 5, and Gemini 7 missions were compared regarding skeletal changes in three major anatomic sites with respect to changes in skeletal density during space flight. Bone-mass changes have been found for the command pilot and the pilot of each mission in the conventional os calcis section, in the combined sections covering 60 percent of the os calcis, and in hand phalanges 5-2 and 4-2. Comparison of radiographically determined losses in X-ray absorbence with X-ray absorbence losses in healthy young men subjected to bedrest immobilization for the same length of time showed that losses for the crewmembers exceeded losses for the bedrest subjects in all cases; this was an indication that restriction of body movement did not represent the only factor involved.

Mack, P. B.↗

Changes in functional construction of bone in rats under conditions of simulated increased gravity.

An investigation was conducted to determine experimentally whether femur bones are altered in cross-sectional area or cross-sectional shape by chronic centrifugation at different G-levels in conformance to Wolff's law. It was found that the centrifuged animals exhibit on the average smaller body masses, femur lengths and femur cross sections, as compared to their corresponding age controls. The mean inhibitory effect of chronic centrifugation upon body and femur growth can be measured in a shortcut approximation by calculating the decrease of body masses and femoral dimensions on a percentage basis.

Amtmann, E.↗

Bone mineral measurement, experiment M078

Measurement tests revealed few deviations from baseline bone mineral measurements after 56 days in a Skylab-type environment. No mineral change was observed in the right radius. One individual, however, showed a possible mineral loss in the left os calcis and another gained mineral in the right ulna. The cause of the gain is unclear but may be attributable to the heavy exercise routines engaged in by the crewmember in question. Equipment problems were identified during the experiment and rectified.

Rambaut, P. C.↗

Determination of bone mineral mass in vivo

Radiographic equipment incorporates two radiation sources, generating high-energy and low-energy beams. Recording equipment measures amount of radiation that has penetrated limb. Data are fed into computer that determines mass of the examined bone.

Cameron, J. R.↗

Collaborative research in cardiovascular dynamics and bone elasticity

A collaborative research program covering a variety of topics of biomechanics and biomedical engineering within the fields of cardiovascular dynamics, respiration, bone elasticity and vestibular physiology is described. The goals of the research were to promote: (1) a better understanding of the mechanical behavior of the circulatory system and its control mechanisms; (2) development of noninvasive methods of measuring the changes in the mechanical properties of blood vessels and other cardiovascular parameters in man; (3) application of these noninvasive methods to examine in man the physiological effects of environmental changes, including earth-simulated gravitational changes; and (4) development of in-flight methods for studying the events which lead to post-flight postural hypotension.

Source record↗

Prevention of bone mineral changes induced by bed rest: Modification by static compression simulating weight bearing, combined supplementation of oral calcium and phosphate, calcitonin injections, oscillating compression, the oral diophosphonatedisodium etidronate, and lower body negative pressure

The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

Schneider, V. S.↗

Continued investigation of kinetic aspects of bone mineral metabolism

The total body calcium in humans was determined by measuring expired Ar-37 after neutron irradiation. The excretion of Ar-37 from humans was found to be much slower than the excretion from rats and dogs, and to be related to the age of a person. A study of the uniformity of the Ar-37 production throughout the thickness of the body was studied using phantoms. The results indicate that it should be possible to obtain a uniformity within plus or minus 3% for the production of Ar-37 per unit of calcium by using a bilateral irradiation. New low background, large volume proportional counters were developed and constructed, for more sensitive measurement of Ar-37 in the expired air from patients. A new irradiation enclosure was developed for measuring total body calcium in rats by the Ar-37 method. With this enclosure the Ar-37 production per gram of calcium is constant with a standard deviation of plus or minus 2.8% for any size rat between 100 and 500 grams. The use of Na-22 as measure of bone replacement in the fractured femur of a dog was not successful.

Palmer, H. E.↗

Development of a bone-fixation prosthetic attachment

An artificial limb attached directly to the bone by a quick-disconnect coupling was tested in-place at a California medical rehabilitation center. Its design concept and development, made possible by multiple spinoffs of aerospace technology, are discussed.

Owens, L. J.↗

Modification of os calcis bone mineral profiles during bedrest

The mineral content of the left central os calcis was determined using the photon absorptiometric technique modified for the space missions to permit area scanning, and was compared with total body calcium balance changes. The instrument consists of a rectilinear scanner that is programmed by a specially designed control module to move a low energy X-ray emitting radionuclide placed in opposition to a detector to scan the foot which is places between them. The foot is placed in a plexiglas box filled with water to provide tissue equivalence and to compensate for irregularities in thickness of tissue cover that surrounds the bone. The mineral content is obtained from basic attenuation equation.

Vogel, J. M.↗

Investigate methods for measuring muscle and bone mass changes in astronauts and animals which occur during space flight

Sodium-22 is being used as a tracer for bone mineral metabolism studies. Dogs are being grown from puppies to adulthood on a diet containing a constant level of sodium-22 in order to uniformly tag the entire skeleton with a long lived radionuclide. This study is still in progress and the dogs are still growing. Potassium-40 measurements were made on people, who are replacing muscle mass lost due to leg injuries, in a second study. It appears that potassium-40 measurements provide an accurate and convenient method for determining relative changes in the muscle content of the leg.

Palmer, H. E.↗

Experiment requirements: Vitamin D metabolites and bone demineralization, Spacelab 2, experiment no. 1

As a contribution toward an understanding of the molecular basis of bone loss, mineral imbalance, and increasing fecal calcium under conditions of prolonged space flight, the blood levels of biologically active vitamin D metabolites of flight crew members will be quantitatively measured. Prior to the mission, the refinement of existing and the development of new techniques for the assay of all vitamin D metabolites will provide an arsenal of methods suitable for a wide range of metabolite levels. In terms of practical application, the analysis of human and animal plasma samples, Spacelab crew plasma samples, and flight hardware are envisioned.

Schnoes, H. K.↗

The influence of exercise on bone atrophy

The relationship between the skeletal system, the muscular system, and exercise in bed rest studies are described. The regime of exercises performed, the mineral balance data derived, and the bone densitometric data obtained are discussed. A brief review of some of the histological results are also given.

Source record↗

Computerized tomographic determination of spinal bone mineral content

The aims of the study were three-fold: to determine the magnitude of vertebral cancellous mineral loss in normal subjects during bedrest, to compare this loss with calcium balance and mineral loss in peripheral bones, and to use the vertebral measurements as an evaluative criterion for the C12MDP treatment and compare it with other methods. The methods used are described and the results from 14 subjects are presented.

Cann, C. E.↗

Long-term follow-up of Skylab bone demineralization

The os calcis mineral was measured in the nine Skylab crew members and in eight control subjects, 5 years after the Skylab Program, utilizing a photon absorptiometric technique. These measurements were compared with preflight measurements in an attempt to discover any long-term effects of space flight on the skeletal system. A statistically significant loss of bone mineral was found in the crew members who flew, but caution is urged in the interpretation of this difference. A recommendation to continue studies of this type is made.

Tilton, F. E.↗

Control of bone remodelling by applied dynamic loads

The data showing the relationship between bone mass and peak strain magnitude prepared and submitted for publication. The data from experiments relating remodelling activity with static or dynamic loads were prepared and submitted for publication. Development of programs to relate the location of remodelling activity with he natural and artificial dynamic strain distributions continued. Experiments on the effect of different strain rates on the remodelling response continued.

Lanyon, L. E.↗