Bone density in adolescents

Article Abstract:

The loss of bone mineral density appears to be an unavoidable consequence of adulthood. While some factors may hasten or slow this loss somewhat, the rate of bone mineral loss appears to average about one percent per year. For this reason, the fate of bone between individuals may vary greatly, even when both people have bone mineral density within the normal range. For example, a person at the lower end of the normal range at 30 years would have the same bone mineral density as a person at the high end of the normal range at 70 years. Many factors affect bone mineral density, and the interaction of various factors is complex. Exercise and any activity that places stress on bone will tend to increase bone mineral density. However, in young women, exercise may also result in amenorrhea, which may act to decrease bone mineral density. Race is another factor that plays an important role in the determination of bone mineral density. It is well established that black women do not suffer osteoporosis at the same rate as white or Asian women. This is generally considered to be a consequence of the higher bone mineral density among black women. In the December 5, 1991 issue of The New England Journal of Medicine, researchers examined 150 girls ranging from 2 to 20 years. Black and white girls were matched for age and sexual development; it was found that there were no racial differences among the prepubertal girls. Bone mineral density increased with the onset of puberty in both groups, but the percentage increase among the black girls was more than three times that of the white girls, giving them an advantage in bone density likely to serve them well later in life. Questions about racial differences in bone development remain, and the findings of the present study are at odds with some previously reported results. Further research should account for discrepancies that might result from the techniques used to measure bone density, and attention should be paid to potential differences in the developmental curves of different parts of the skeleton. Furthermore, it would be important to measure estrogen levels in teenage black and white girls to determine the physiological basis for the observed differences. Greater understanding of the development of bone in the teenage years may improve the prevention of mineral loss in later years. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Physiological aspects, Health, Osteoporosis, Puberty, Health and race, Ethnic groups, Blacks, Black race

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Nontraumatic necrosis of bone (osteonecrosis)

Article Abstract:

Osteonecrosis, or death of a segment of bone, is caused by an interruption in the blood supply to the bone. The blood supply may be interrupted when blood vessels are blocked or injured. Formation of areas of dead tissue in the bone marrow causes the death of surrounding bone cells. Many different disorders or injuries are associated with osteonecrosis. Corticosteroid drugs can cause a severe form of the disorder. Osteonecrosis is relatively common, and it is responsible for 10% of joint replacements. Most patients experience mild pain, but a few have intense pain. Magnetic resonance imaging (MRI), computed tomography (CT imaging) and bone scans are used to diagnose early osteonecrosis, in addition to medical history and physical examination. X-rays are often used to follow the course of the disease, especially in the hip. Osteonecrosis patients may be treated with anti-inflammatory drugs and exercise depending on the cause of the disorder. Use of hyperbaric oxygen that is under higher than normal pressure is an experimental treatment used on some patients. Others may undergo a joint replacement or bone graft.

Bones, Osteonecrosis

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The effect of enforcing tobacco sales laws on adolescents' access to tobacco and smoking behavior

Article Abstract:

Laws that force store owners not to sell tobacco to minors may not necessarily reduce the use of tobacco by teenagers. Researchers asked 16-year-old girls to try to buy cigarettes in three Massachusetts communities that enforced the state law banning cigarette sales to minors and three that did not. Eighty-two percent of the stores in communities that enforced the law obeyed it, compared to 45% of the stores in communities that did not enforce it. However, girls in both communities still seemed to have equal access to cigarettes. Many teens go to other communities or ask someone else to buy cigarettes for them.

Purchasing, Laws, regulations and rules, Retail industry, Retail trade, Teenagers, Youth, Smokers, Cigarettes

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