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Biomedical subjects

M M Chan

Publications and source records attributed to M M Chan.

66 records · Page 4Linked to original sources
PubMed1977

Effect of ethane-1-hydroxy-1,1-diphosphonate (EHDP) and dietary fluoride on biomechanical and morphological changes in chick bones.

There are only a few papers in the literature in which parameters related to bone strength are examined over wide range of fluoride concentrations. In this report, chicks were used and fed diets containing fluoride added at 0, 50, 200, or 800 ppm in preparation for measurements on bone strength. The diets were fed for 20 days. After 10 days, the birds were also injected daily with solutions containing either isotonic saline or 5 mg of ethane-1-hydroxy-1,1-diphosphonate (EHDP) as phosphorus/kg body weight or 10 mg of EHDP as phosphorus/kg body weight. The effects of added fluoride and EHDP on bone morphology and the biomechanical properties of bone were then examined. The rate of bone formation was assessed using histological and tetracycline labeling techniques. Administration of high fluoride and/or EHDP resulted in significant changes in bone morphology. The changes effected by the administration of EHDP appeared independent of fluoride induced changes. Biomechanical studies also indicated that both high levels of fluoride and EHDP caused a significant reduction in bone torsional breaking strength. The reductions in breaking strength were independent of changes in body size.

Animals↗
PubMed1976

Effects of fluoride and ethane-1-hydroxy-1,1-diphosphonate on bone metabolism in the growing chick.

White Leghorn cockerols were fed a semipurified diet (containing fluoride at 0 to 800 ppm) from the day of hatching. The birds were also injected daily with solutions containing ethane-1-hydroxy-1,1-diphosphonate (EHDP) at concentrations ranging from 5 to 20 mg as phosphorus/kg of body weight or isotonic saline. Changes in bone mineral composition and plasma Ca, Mg and F were determined as well as alterations in bone pyrophosphatase and the amounts of bone cyclic-3',5'-adenosine monophosphate (cAMP). Since dietary fluoride in high amounts is known to stimulate new bone formation, the purpose of the study was to assess whether a potent inhibitor of mineralization, such as EHDP, might alter the response to high dietary fluoride. Although bone fluoride and magnesium were increased in relationship to dietary fluoride, the administration of EHDP had little effect on these changes at low to moderate levels of fluoride. The levels of soluble bone pyrophosphatase were not greatly influenced by changes in dietary fluoride. Administration of EHDP at 20 mg P/kg, however, typically decreased the levels of bone pyrophosphatase. Bone cAMP did not appear to be influenced by either dietary fluoride or EHDP. Using tissue culture techniques, the effects of fluoride on calcium uptake and release from embryonic chick bone were also studied. The presence of 1 mM fluoride in the medium appeared to stimulate calcium uptake and reduced calcium release from chick bone. In general, the results were in keeping with previous suggestions that the major effect of fluoride on bone is the formation of fluoroapatite and subsequent effects this may have on other metabolic alterations.

Alkaline Phosphatase↗
PubMed1975

Effects of nutritional copper deficiency on the biomechanical properties of bone and arterial elastin metabolism in the chick.

Increased bone fragility was observed in chickens fed diets containing less than 1 ppm copper. Using a device that was designed to measure torsion during fracture, it could be demonstrated that bone from copper-deficient chicks fractured with less deformation and torque than bone from control chicks. The collagen of bone from copper-deficient chicks appeared to contain fewer cross-links than normal bone. The introduction of artificial cross-links into collagen from copper-deficient chick bone by formaldehyde and NaBH4 treatments improved bone strength and strain (deformation) so that it was comparable with normal bone. Copper deficiency blocks the formation of cross-links in collagens and elastin from various tissues. It is felt that the bone fragility related to nutritional copper deficiency is the result of decreased bone collagen cross linking. Arterial elastin metabolism was also investigated. By radioactively labeling arterial soluble elastin (tropoelastin) in vivo by an intraperitoneal injection of [G-3H]valine, it could be demonstrated that copper deficiency appeared to reduce its rate of metabolic turnover. Soluble elastin or tropoelastin is assumed to be the precursor of mature or insoluble elastin. The observations presented here are consistent with the view that by retarding the steps associated with elastin cross-link formation, the incorporation of soluble elastin into mature elastin may be retarded as well.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

The effect of fluoride supplementation on the strength of osteopenic bone.

The strength of osteopenic bone from calcium deprived rats, quail and roosters was significantly reduced after fluoride supplementation. Using a device which measures torque, femurs from rats fed low calcium diets with 100 parts per million fluoride added to the water supply fractured at lower torque values than those values observed for rats fed a low calcium diet without fluoride. Fluoride administration and calcium restriction in adult roosters and young Japanese quail also resulted in a reduction in bone strength. This detrimental effect on bone strength must be considered in any therapeutic attempt to use fluoride ion to stimulate bone formation in osteopenic bone disorders.

Animals↗