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Results for “Bone Demineralization, Pathologic”

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PubMed2001

[Anemia and limping in a vegetarian adolescent].

UNLABELLED: A vegan diet in the child and adolescent can induce severe bone sequelae by rickets and osteomalacia and megaloblastic anemia by cobalamin deficiency. CASE REPORT: A 15-year-old adolescent was hospitalized because of lameness and pallor. The lameness was explained by femoral epiphysiolysis caused by rickets with severe hypocalcemia. The pallor, jaundice and splenomegalia were due to cobalamin-deficiency megaloblastic anemia. A prolonged supplemental diet with calcium, vitamins D and B12 as well as orthopedic treatment stabilized the bone lesions. The megaloblastic anemia was cured by parenteral cobalamin. The adolescent and his brother were victims of a diet imposed by a cult and a lack of care due to their parents refusing that a vegan diet was the cause of the deficient pathology. Penal proceedings led to the incarceration of the parents and to the placement of the children. COMMENTS: Deficiencies in calcium and vitamins D and B12 may be severe in a child's development with a vegan diet. This case report reveals the social and legal problems of an inappropriate diet in infancy imposed by parents who are followers of a fundamentalist church. Beyond the management of children in cults, health professionals have to prevent, screen and supplement the deficient diet.

Adolescent↗
PubMed1998

Factors affecting bone demineralization and blood lead levels of postmenopausal women--a population-based study from Germany.

We investigated the influence of various lifestyle factors on blood lead levels in postmenopausal women from the general population of Germany. Particular consideration was given to those factors which are suspected to be related to bone demineralization. The study population consisted of 424 women, aged 45 to 80 years, who were examined in a substudy of the National Health and Nutrition Survey called VERA (Verbundstudie Ernährungserhebung, und Risikofaktorenanalyse) from 1987 to 1988. Mean blood lead level was 61.4 micrograms/liter (SD, 27.3). In multiple linear regression analysis alcohol consumption, former use of oral contraception, hematocrit, and age were positively associated with blood lead levels, whereas calcium intake and high physical activity showed a negative association with blood lead levels. Some of the identified risk factors which are suspected to exert their influence on blood lead levels by affecting bone demineralization can be influenced by change of individual behavior. Thus, we conclude that reduction of alcohol consumption, adequate calcium intake, and physical activity may reduce blood lead levels as well as negative health effects of osteoporosis in postmenopausal women.

Adult↗
PubMed1996

Effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats: enhancement with zinc.

The effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats was investigated. Skeletal unloading was designed using a model of hindlimb suspension; the rats were fed for the 4 days of unloading. The metaphyseal tissues obtained from normal and skeletal-unloaded rats were cultured for 48 h in medium containing either vehicle or vitamin K2 (10(-6) and 10(-5) M). The presence of vitamin K2 (10(-5) M) caused a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal rats. Such an effect was not seen in the bone tissues from skeletal-unloaded rats. Additionally, the presence of zinc sulfate (10(-5) M) in effective concentration produced a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal and skeletal-unloaded rats. In the presence of vitamin K2 (10(-5) M), the stimulatory effect of zinc sulfate on bone calcium content was appreciably enhanced; although this effect was completely abolished by cycloheximide (10(-6) M), an inhibitor of protein synthesis. This study demonstrates that the effect of vitamin K2 (menaquinone-7) on trabecular bone calcification in rats with skeletal unloading-induced osteopenia is enhanced by zinc in vitro. The enhancement with zinc may be based on a newly synthesized protein in the bone tissues.

Alkaline Phosphatase↗
PubMed1979

Prolonged weightlessness and calcium loss in man.

Data have been accumulated from a series of studies in which men have been subjected to weightlessness in orbital space flight for periods of up to 12 weeks. These data are used to predict the long term consequences of weightlessness upon the skeletal system. Space flight induced a loss of calcium which accelerated exponentially from about 50 mg/d at the end of 1 week to approx. 300 mg/d at the end of 12 weeks. The hypercalciuria reached a constant level within 4 weeks while fecal calcium losses continued to increase throughout the period of exposure. This apparent diminution of gastrointestinal absorptive efficiency was accompanied by a slight decline in the plasma level of parathyroid hormone and a slight elevation in the plasma level of calcium and phosphorus. Although losses in mineral from the calcaneus were closely correlated with the calcium imbalance, no changes were detected in the mineral mass of the ulna and radius. From the data presented it is concluded that the process of demineralization observed in space flight is more severe than would be predicted on the basis of observations in immobilized, bed rested, or paralyzed subjects. It is, moreover, suggested that the process may not be totally reversible.

Bone Demineralization, Pathologic↗
PubMedDate not supplied

U.S. manned space flight: the first twenty years, a biomedical status report.

In the last 20 years, the biomedical problems facing man in space have been brought into sharper focus. Space motion sickness is presently our most serious problem. Its etiology remains obscure, but the "sensory conflict" theory appears most plausible. No valid predictive tests of susceptibility exist and presently we must rely on medication for prevention or mitigation of symptoms. Adaptation/biofeedback techniques may prove useful. Cardiovascular "deconditioning" may be effectively attenuated by use of anti-g suits or plasma expanding techniques. Recent bedrest simulation studies would seem to indicate that concerns about chronically elevated central venous pressure during space flight are unfounded. The loss of red cell mass in space flight appears to be self-limited, independent of mission duration, and not of clinical concern, based on recent Soviet experiences. And finally, clodronate, a new diphosphonate effective in preventing hypercalciuria and negative calcium balance in normal human bedrested subjects, may prove effective in preventing or lessening skeletal mineral loss in space.

Adaptation, Physiological↗
PubMed1988

The prevention of adverse physiological change in Space Station crewmembers.

Various physiological countermeasures, consisting primarily of isotonic and isometric exercises but also including prescribed nutrient intake, have been used in all manned spaceflights exceeding about one month in duration. So consistent has been this practice that the effects of weightlessness on the human, unconfounded by the use of countermeasures, are difficult to discern. Equally elusive, in the absence of control studies conducted in weightlessness, is an accurate assessment of the efficacy of the countermeasures themselves. Changes in body composition occurring during and following flights from Gemini through Shuttle, when compared with changes during and following bedrest, demonstrate certain mitigating effects that may be attributable to countermeasures and which provide some rationale for the choice of countermeasures in the Space Station.

Adaptation, Physiological↗
PubMed1984

NASA' s life sciences and space radiation biology.

Plans for the various missions in which men and women are expected to participate during the next 10 years are outlined. Such missions include flights of up to three months duration in low earth orbit as well as possible short excursions to geosynchronous orbit. Research activities are described which cover the full spectrum of physiological and psychological responses to space flight. These activities are shown to contribute to the ongoing Shuttle program and the future Space Station. The paper includes a summary of the major technical thrusts needed to support extended habitation in space.

Adaptation, Physiological↗
PubMed1989

Thin film bioreactors in space.

Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers us an opportunity to learn more about basic biological systems with one important variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would enable us to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

Animals↗
PubMed1992

Combined injury syndrome in space-related radiation environments.

The risk of combined injury (CI) to space travelers is a function of exposure to anomalously large surges of a broad spectrum of particulate and photon radiations, conventional trauma (T), and effects of weightlessness including decreased intravascular fluid volume, and myocardial deconditioning. CI may occur even at relatively low doses of radiation which can synergistically enhance morbidity and mortality from T. Without effective countermeasures, prolonged residence in space is expected to predispose most individuals to bone fractures as a result of calcium loss in the microgravity environment. Immune dysfunction may occur from residence in space independent of radiation exposure. Thus, wound healing would be compromised if infection were to occur. Survival of the space traveler with CI would be significantly compromised if there were delays in wound closure or in the application of simple supportive medical or surgical therapies. Particulate radiation has the potential for causing greater gastrointestinal injury than photon radiation, but bone healing should not be compromised at the expected doses of either type of radiation in space.

Bone Demineralization, Pathologic↗
PubMed1994

Bone demineralization induced by cementless alumina-coated femoral stems.

The biologic compatibility of ceramic materials has been widely demonstrated, and alumina (Al2O3) has been used extensively in clinical applications for nearly 20 years. The authors examined the behavior of bone tissue adjacent to the alumina coating in eight cementless hip prosthetic stems that appeared radiologically stable and were explanted because of pain. Histologic evaluation demonstrated the presence of a consistent layer of decalcified bone tissue in continuity with and parallel to the prosthetic interface. Based on laboratory findings, the authors attribute this demineralization phenomenon to a high local concentration of aluminum ions with metabolic bone disease, which is histologically comparable to the osteomalacic osteodystrophy described in dialysis patients. These findings must be carefully considered given the potential long-term implications for alumina-coated implants.

Aged↗
PubMed2000

Human water, sodium, and calcium regulation during space flight and exercise.

When one is exposed to microgravity, fluid which is normally pooled in the lower extremities is redistributed headward and weight bearing bones begin to demineralize due to reduced mechanical stresses. The kidney, which is the primary regulator of body fluid volume and composition, responds to the fluid shift and bone demineralization by increasing the urinary output of water, sodium, and calcium. This research involves developing a mathematical description of how water and electrolytes are internally redistributed and exchanged with the environment during space flight. This model consequently involves kidney function and the associated endocrine system. The model agrees well with actual data, including that a low sodium diet can prevent bone demineralization. Therefore, assumptions made to develop the model are most likely valid. Additionally, various levels of activity are also considered in the model since exercise may help to eliminate some of the undesired effects of space flight such as muscle atrophy and bone demineralization.

Aldosterone↗
PubMed1999

Human water, sodium, and calcium regulation during space flight and exercise.

When one is exposed to microgravity, fluid which is normally pooled in the lower extremities is redistributed headward and weight bearing bones begin to demineralize due to reduced mechanical stresses. The kidney, which is the primary regulator of body fluid volume and composition, responds to the fluid shift and bone demineralization by increasing the urinary output of water, sodium, and calcium. This research involves developing a mathematical description of how water and electrolytes are internally redistributed and exchanged with the environment during space flight. This model consequently involves kidney function and the associated endocrine system. The model agrees well with actual data, including that a low sodium diet can prevent bone demineralization. Therefore, assumptions made to develop the model are most likely valid. Additionally, various levels of activity are also considered in the model since exercise may help to eliminate some of the undesired effects of space flight such as muscle atrophy and bone demineralization.

Aldosterone↗