Search

Osteoporosis is a condition in which bone density is reduced, which can result in decreased bone strength. This condition inevitably accompanies old age, but the process is faster in women, particularly after menopause. Two factors which influence osteoporosis are inadequate absorption of calcium and increased bone resorption (removal by absorption). Following gastrectomy (surgical removal of all or a portion of the stomach) calcium absorption is impaired. The usefulness of calcium supplementation in osteoporosis has not been determined. Some reports suggest that calcium supplementation may be useful in preventing osteoporosis or reducing further bone resorption, although the changes that have already taken place appear to be irreversible. Better evaluation of the amount of osteoporosis present in bone is now possible with improved methods for measuring of bone mineral status, particularly dual energy X-ray absorptiometry. A study was undertaken of 16 men who had undergone gastrectomy over 30 years ago. These men are now between the ages of 50 and 72. Measurements of bone mineral density were obtained for each patient using dual energy X-ray absorptiometry, a procedure which uses a small X-ray source and detector to determine the bone mineral density. Six men were initially found to have low bone mineral density. They were given calcium supplementation for six months. This supplementation did not affect the loss of bone density over a six-month period and was of no significant benefit to the treated patients. (Consumer Summary produced by Reliance Medical Information, Inc.)

Systemic lupus erythematosus (SLE) affects women more often than men and occurs primarily during the reproductive years. Long-term use of corticosteroids is used as treatment of SLE. Estrogen deficiency and the use of glucocorticoids are associated with the development of osteoporosis, a reduction in bone mass below that expected for age and sex. Osteoporosis is related to an increased risk of fractures. Dual energy X-ray absorptiometry, a new technique for rapid assessment of bone mineral density (BMD), was used in patients with SLE who were taking corticosteroids, to assess possible drug effects on their bone mass. This technique provides clinicians with a significant advancement in the assessment of BMD; precision and quality of the image are high and the procedure causes no discomfort to the patient. A reduction in BMD was seen in patients with SLE who were taking steroids; however, since patients were assessed six months after initiation of steroids, the period when BMD was greatest may have been missed. Continuing reduction in BMD results in a greater risk of fracture than chronically low BMD. In addition, patients in this study were premenopausal and primarily in their 30s; the investigators feel it may be more relevant to assess patients as they reach menopause, when there is a higher risk of osteoporosis. Lupus patients and those receiving steroids are not necessarily at risk for the development of osteoporosis. Further studies are needed to determine if a chronically low BMD or a decreasing BMD is most important in predisposition to osteoporosis. It is important to continue to assess patients as they approach and go through menopause, especially using dual energy X-ray absorptiometry, a low risk and convenient procedure. (Consumer Summary produced by Reliance Medical Information, Inc.)

A number of the more important environmental impacts of the operation of large coal-fired power plants are associated with the very large quantities of solid materials resulting from these processes. These are, principally: coal ash residues, and solid residues of flue gas desulfurisation processes. By far the greater proportion of these materials, generally around 80% of the total solid discards from the electricity supply industry, comprise fly ash from the particulate collection equipment and bottom ash from the hoppers under the economisers and air preheaters of large pulverised coal boilers. The utilisation and disposal of the fly ash residues has been the subject of a great deal of development activity over many decades. In the main, the emphasis has been on the increased use of fly ash materials in high volumes, as constituents of cements and mortars, or for the manufacture of concrete and aggregate materials. The unsold ashes are used for land reclamation and for beneficial landfill, wherever possible. In recent years, there has been increasing interest in the processing of boiler fly ashes to improve ash quality and consistency, and in the manufacture of high-value secondary products. The utilisation of power station fly ashes depends on their physical and chemical properties, and there have been a number of recent developments in power plant design and operation, which have resulted in significant changes in the characteristics of fly ashes, eg the progressive introduction of NO_x emission control technologies and in-furnace NO_x reduction technologies. The increasing interest in the co-firing of non-conventional fuels such as petroleum coke and biomass/waste materials has resulted in the production of mixed and more complex materials. The paper will present a review of the major developments, which can affect coal fly ash quality and discuss the impact of these issues on the utilisation of fly ashes as feed materials for the manufacture of high-value secondary products.
© 2002 Society of Chemical Industry