Bone Mass Content Research Articles

The relation between resonant frequencies and torsional stiffness of long bones in vitro. Validation of a simple beam model

The results of vibration analysis experiments and impact torsion tests performed on excised animal long bones were used to validate a simple beam model for the prediction of torsional stiffness from resonant frequencies. Resonant frequency data on two mutually perpendicular bending vibration modes of 142 excised long bones were evaluated. Torsional stiffness of the same bones had been determined by an impact torsion test. Using a simple beam model, a theoretical relation between resonant frequencies and torsional stiffness was derived. If total bone mass and bone length are known, the formula thus derived allows one to calculate torsional stiffness from resonant frequencies. Linear regression analysis shows a strong correlation between the measured and the calculated torsional stiffness for sheep femora ( r 2 = 0.63, n = 24), dog femora ( r 2 = 0.94, n = 34), dog tibiae ( r 2 = 0.79, n = 18) and monkey radii ( r 2 = 0.77, n = 66). It was found that this linear relation was valid not within one bone type alone. Linear regression analysis on the combined data of all bones demonstrated that all bones obeyed the same global linear relation between measured and the calculated torsional stiffness ( r 2 = 0.98, n = 142). This implies that one and the same beam model is valid for the different bone types investigated. The calculation of stiffness from resonant frequencies, however, requires total bone mass, m, and length to be known. In view of in vivo applications, the feasibility of using total bone mineral content (TBMC) as a measure for m was investigated. A good linear correlation was found between total bone mass and total bone mineral content. The correlation between torsional stiffness using TBMC data and measured torsional stiffness was still highly satisfying. Finally, a good linear correlation was observed between the properties of left and right bone from a single specimen. These results demonstrate a simple relation between resonant frequencies and bone mechanical properties in vitro. Under the condition that in vivo effects (muscles, skin, joints, etc.) on the vibrational behaviour can be accounted for properly, the results are promising as to the feasibility of the resonant frequency technique for fracture healing monitoring and osteoporosis evaluation.

Fracture risk as determined by prospective and retrospective study designs.

Both retrospectively and prospectively designed studies consistently show low bone mass and/or bone mineral content (BMC) to be risk factor for low-trauma fractures in postmenopausal women. Along with the reports of such studies there has been concern expressed that BMC measurements overlap between fracture groups, i.e., some women with high BMC develop fractures and some women with low BMC do not. In these commonly used epidemiologic study designs, BMC does not discriminate between those who have and have not experienced the untoward event at some level of the exposure factor. The ability to discriminate is more properly determined by the sensitivity and specificity of the measured value. To contrast the concepts of risk and sensitivity, a nested case-control study was conducted within a 24-year cohort study of women at risk for osteoporosis. We found that for each 1.0 decrement of BMC z-scores, the adjusted relative risk for the prospective study design was 1.67, while the odds ratio obtained from the most recent BMC z-score measurements was 1.87. A receiver operating characteristic (ROC) curve, calculated from the nested case-control study data, showed that BMC z-scores, measured after low-trauma fracture, have both low sensitivity and low specificity to detect existing fracture status.

Effect of dietary lactose on salt-mediated changes in mineral metabolism and bone composition in the rat

The effects of salt (sodium chloride) supplementation of rat diets (80 g/kg diet), with or without lactose (150 g/kg), were studied in weanling rats over 14 d. Dietary salt increased water intake and reduced weight gain and food conversion efficiency, but these variables were unaffected by lactose. Salt-supplemented rats exhibited a three- to fivefold increase in urinary calcium excretion and a small increase in urinary magnesium and phosphorus excretion, irrespective of dietary lactose content. In addition, salt supplementation reduced plasma alkaline phosphatase (EC 3.1.3.1) activity. Lactose increased urinary Ca and Mg excretion and plasma Ca and P concentrations. Salt reduced tibia mass but not tibia mass expressed relative to body-weight, but neither variable was affected by lactose. Both tibia Mg content and concentration were reduced by salt but unaffected by lactose, and neither tibia P content nor concentration was affected by salt or lactose. Tibia Ca content was reduced by salt but this was prevented by lactose. Tibia Ca concentration was unaffected by salt or lactose, although there was a reduction (not significant) in tibia Ca concentration in animals fed on the lactose-free diet. These results show that lactose had no independent effect on bone and that reduced accretion of bone mass and mineral content in rats fed on the high-salt diets was due, at least in part, to reduced growth. Failure to offset sodium-induced hypercalciuria by a compensatory increase in net Ca absorption may have contributed to reduced bone Ca accretion. The protective effect of lactose against reduced bone Ca accretion may be due to increased Ca absorption.

Trabecular bone mass and bone content of diet-related Trace elements among the Prehispanic inhabitants of the western Canary Islands

The trabecular bone mass (TBM) of 29 bone cylinders (obtained at the iliac crest with a Bordier's trephine) belonging to non-sanile adult skeletons of the prehispanic inhabitants of the Western Canary Islands was determined histomorphometrically. Scanbning electron microscope and/or binocular microscope observations of the cylinders were also performed in order to exclude diagenetic alterations of the bones. Bone content of Sr, Mg, Mn, Co, Cu, Fe and Zn of the skeletons and of soil samples from the burials where they were found were also measured. These procedures were also performed in a control group of 21 preciously healthy individuals dead as a result of trauma.

Increase of vertebral density by combination therapy with pulsatile 1-38hPTH and sequential addition of calcitonin nasal spray in osteoporotic patients

Combination therapy with the biologically active (1-38) human parathyroid hormone peptide and calcitonin using pulsatile and sequential activation of the skeleton for 14 months in patients with low-turnover osteoporosis resulted in an increase in trabecular bone mass. These favorable responses were observed without any significant changes in cortical (forearm) bone mass content.

Bone changes in rats with adjuvant arthritis: treatment with 1 alpha-hydroxycholecalciferol.

Adjuvant arthritis was induced in female Lewis rats by the injection of Mycobacterium butyricum in mineral oil in a hindpaw. Bone changes due to polyarthritis were evaluated in the tibia metaphyseal region of the noninjected hind leg. A decrease in bone mass and mineral content was observed in the affected bone. accompanied by a marked increase in bone resorption. Non-arthritic and arthritic rats were treated with the synthetic vitamin D analogue, 1 alpha-hydroxycholecalciferol (0.01 to 1.0 micrograms/kg/day orally) for 28 days. Treatment resulted in a small increase in bone weight and mineral content in the non-arthritic rats. Arthritic rats exhibited a larger increase in bone weight, hydroxyproline and calcium content. These beneficial effects were correlated with the ability of 1 alpha-hydroxycholecalciferol to increase extracellular calcium and phosphorus levels, as measured by the increased urinary excretion of calcium and inorganic phosphate and by the increase in serum calcium. Bone resorption and new bone formation were not affected by the treatment.

Interrelationship between metacarpal bone mass and bone mineral content in renal transplant recipients.

Metacarpal bone mass, bone mineral content in the forearm and bone mineral concentration were measured in 54 renal transplant recipients with a well functioning renal transplant a mean of 67 months after transplantation. Significantly decreased values of metacarpal bone mass, bone mineral content and bone mineral concentration were found. A highly significant correlation between metacarpal bone mass and bone mineral concentration was found in renal transplant recipients, probably indicating that changes in the amount of cortical bone and bone mineral occur simultaneously after renal transplantation.

Interrelationship Between Metacarpal Bone Mass and Bone Mineral Content in Nondialyzed and Dialyzed Patients with Chronic Renal Failure

Metacarpal bone mass (D2-d2)/D2 measured on radiographs, and bone mineral content (BMC) measured by photon absorptiometry, were studied in the forearms of 30 nondialyzed and 25 hemodialyzed patients with chronic failure and in a group of normal subjects. Metacarpal bone mass was reduced in nondialyzed women with chronic renal failure and the amount of bone mineral reduced both in males and females with chronic renal failure, whereas these measurements were normal in dialyzed patients with chronic renal failure. Bone mineral content in the forearm and metacarpal bone mass decreased with age, both in women with chronic renal failure and in normal women, the decrease being more pronounced in women with chronic renal failure than in normal women. No age-related decrease was seen in males. Bone mineral content corrected for the size of bone (BMC') decreased with age both in males and in females. Highly significant correlations were found between metacarpal bone mass and BMC' in nondialyzed and dialyzed patients with chronic renal failure, whereas no significant correlation could be demonstrated in normal subjects. The study indicates that changes in metacarpal bone mass and in BMC to some degree occur simultaneously in patients with chronic renal failure; an accelerated loss of bone mass and of bone mineral with age may be seen in women with chronic renal failure compared to normal women.

Effect of different calcium intakes on bone mineral composition in rats with a calcitonin secreting tumour.

The effects of hypercalcitoninaemia and different calcium intakes on bone composition were studied in rats with and without a transplanted calcitonin secreting tumour (MCT). The serum concentrations of immunoreactive calcitonin (iCT) increased progressively after transplantation. After 32 weeks the serum iCT concentrations in MCT rats were about 5-fold higher and serum ionized calcium was significantly reduced compared to control animals. In rats with hypercalcitoninaemia eating a standard calcium (0.9%) diet for 32 weeks, the dry weight and calcium and sodium content of the long bones were reduced compared to control rats without tumours or rats with a prolactin secreting tumour. The feeding of low (0.09%), medium (0.4%) and high (1.8%) calcium diets to MCT-rats resulted in corresponding levels of total and ionized serum calcium, but there was no difference in iCT concentrations. The MCT-rats taking the low calcium diet had decreased bone mass and calcium content compared to the other dietary groups. In conclusion, rats on normal calcium intake and carrying a calcitonin secreting tumour, but not a prolactin secreting tumour, had reduced femoral dry weight and bone mineral calcium content. Different calcium intake regimens did not affect hypercalcitoninaemia due to a tumour, but parallel changes in femoral dry weight and calcium content were found.

Effect of Estrogen onin Vivoandin VitroCollagen Biosynthesis and Maturation in Old and Young Female Guinea Pigs1

Study of collagen composition and in vivo and in vitro collagen biosynthesis and maturation in 10-day-old carrageenan-induced granulomas from female guinea pigs demonstrated that old animals have decreased amounts of neutral salt and acid soluble collagen, decreased in vitro biosynthesis and turnover, and lower ratios of proline to hydroxyproline (P: OH-P) in all collagen fractions. At any age the P:OH-P ratios appeared to reflect the rate of synthesis and turnover of collagen in the tissue studied, the more soluble, more immature, less polymerized forms having higher ratios. Estradiol administration to old animals reversed the values toward those found in young animals. In both young and old, estradiol decreased total collagen content of skin and granuloma while increasing bone mass, bone collagen, and calcium content. In the granuloma, estrogen reduced the amount and content of soluble collagen, almost eliminating the acid soluble; P:OH-P ratios in all fractions were increased and proline content of the...