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Biomedical subjects

J C Stevenson

Publications and source records attributed to J C Stevenson.

At least 127 records · Page 7Linked to original sources
PubMed1991

Role of oestrogen in the development of osteoporosis.

The evidence now strongly supports a central role for oestrogen in the maintenance of the normal female skeleton. Loss of endogenous oestrogen leads to a period of accelerated bone loss which can be prevented with appropriate oestrogen replacement. The route of administration is not important provided adequate dosages are prescribed. Oestrogens may exert their actions by a direct steroid receptor mechanism or via local and/or systemic factors such as cytokines, prostaglandins or calcitonin. As the requirement for osteoporosis prevention grows, it is essential that the extent of the involvement oestrogen has in skeletal homeostasis is fully recognized.

Adult↗
PubMed1991

Changes in body composition with danazol therapy.

Whole body lean and fat mass measurements by dual energy x-ray absorptiometry were performed in 14 premenopausal women undergoing danazol treatment for endometriosis. After 6 months, there was a significant increase in lean tissue mass. Body fat decreased but this was significantly less in the android (upper body segment) region than in the gynoid (lower body segment) region. Danazol thus has both anabolic and androgenic effects on body composition. Dual energy x-ray absorptiometry provides a new, noninvasive, and rapid means of studying body composition.

Adipose Tissue↗
PubMed1990

Effects of transdermal versus oral hormone replacement therapy on bone density in spine and proximal femur in postmenopausal women.

66 early postmenopausal women were randomised to 28-day cycles of either transdermal hormone replacement therapy--continuous oestradiol 17-beta 0.05 mg daily, with norethisterone acetate 0.25 mg daily for 14 of each 28 days--or oral therapy--continuous conjugated equine oestrogens 0.625 mg daily, with dl-norgestrel 0.15 mg daily for 12 of each 28 days. An untreated reference group of 30 women were studied concurrently. Bone density was measured in the lumbar spine and proximal femur by dual photon absorptiometry at 6-month intervals for 18 months. Skeletal turnover was assessed by serum measurements of calcium, phosphate, and alkaline phosphatase, and by urine estimations of hydroxyproline/creatinine and calcium/creatinine excretion. In both treatment groups by comparison with the untreated groups by comparison with the untreated group, bone density increased in the vertebrae and proximal femur and biochemical measurements indicated a significant reduction in bone turnover.

Absorptiometry, Photon↗
PubMed1990

Transdermal administration of oestrogen/progestagen hormone replacement therapy.

The effects of an oestrogen/progestagen transdermal therapeutic system (TTS) were evaluated in sixteen oestrogen-deficient women. The patients applied conventional oestradiol-TTS for 14 days, then two combined norethisterone acetate/oestradiol patches for a further 14 days. The treatment was repeated for five cycles. Ten patients then underwent metabolic studies. One patient had amenorrhoea, but the rest experienced regular withdrawal bleeding which was seldom heavy. Fourteen endometrial biopsy samples were taken during the fifth treatment cycle; none showed proliferative or hyperplastic features. The effects of transdermal norethisterone acetate on symptoms, lipid metabolism, and psychological status were determined by comparing features in the oestrogen-only phase and in the combined phase; the effects were very mild. These preliminary findings show that transdermal progestagen can be successfully administered in hormone replacement therapy to prevent endometrial proliferation while minimising the adverse effects that may be seen with oral administration.

Administration, Cutaneous↗
PubMed1990

Pathogenesis, prevention, and treatment of osteoporosis.

Half of women who develop osteoporosis will sustain some form of osteoporotic fracture. Fracture incidence is directly related to bone density, which is determined by peak adult bone mass and the amount of postmenopausal bone loss. Peak adult bone mass is, to a large extent, genetically determined, but hormonal factors (time since menopause, number of pregnancies, and previous oral contraceptive use) are the prime determinants of bone density after menopause. Time elapsed since menopause, rather than chronological age, determines skeletal composition; oral contraceptive use and parity appear to have a positive effect on the skeleton. Nonhormonal factors such as body weight and some forms of weight-bearing exercise appear to correlate with bone density at certain skeletal sites. Hormone replacement in the early postmenopausal period is the most effective means of preventing osteoporosis and can have a major impact on the incidence of subsequent fracture. Calcitonin may be used as an alternative when hormonal therapy is contraindicated. Established osteoporosis is difficult to treat because bone density has fallen below the fracture threshold and trabecular elements may have been lost. Antiresorptive agents can be used to prevent further bone loss, and stimulation of new bone formation by use of anabolic steroids or fluoride may increase the overall amount of bone.

Bone Density↗
PubMed1990

Immunoglobulin haplotypes: markers of reproductive success?

Immunoglobulin haplotypes are highly polymorphic and are useful for analyses of both macro- and microdifferentiation of populations. The origins of this diversity are not known, but recent reports suggest strong selection at this locus. Increased rates of first-trimester spontaneous abortions have been reported when parents share GM phenotypes. Reduced fertility has been observed in mixed European descent white and Hutterite populations when both parents share immunoglobulin haplotypes. Population samples with completed family information and GM haplotype data are rare; the objective here is to provide this information on another sample. A sample of 242 Mennonite couples with mothers older than 40 years was divided into 3 groups of matings based on how many haplotypes were shared: 0, 1, or 2. The distribution of mean completed family sizes for the three groups were 3.35 +/- 1.85 (n = 23), 3.47 +/- 1.69 (n = 128), and 3.37 +/- 1.60 (n = 91), respectively; these values were not significantly different (F = 0.145, p = 0.865). The log-rank test was used to compare the time-to-next-birth curves. The intervals between first and later births (2-4 births) were not significantly different for the three subgroups either. There is also only limited evidence for segregation distortion in another sample of 923 offspring (in which at least one parent is heterozygous.

Abortion, Spontaneous↗
PubMed1989

Altered calcitonin gene in a young patient with osteoporosis.

To assess whether calcitonin is important in maintaining the integrity of bone the calcitonin gene of a young male patient with osteoporosis and no detectable plasma concentrations of calcitonin was studied. Genomic Southern blots with various restriction enzymes showed no large abnormalities in his calcitonin gene. Genomic clones representing his calcitonin gene were then analysed. His gene encoded normal precursor polypeptides for calcitonin and calcitonin gene related peptide; the only abnormality identified was a single base insertion in the intron separating exons IV and V of the gene. The affected sequence is homologous with an intron sequence from beta globin that is implicated in splicing and forming a crucial intermediate structure during the maturation of messenger RNA. The change observed may be responsible for the patient's calcitonin deficiency and consequently for his condition, suggesting that calcitonin is important in preventing bone loss.

Base Sequence↗
PubMed1989

Determinants of bone density in normal women: risk factors for future osteoporosis?

Postmenopausal osteoporosis is an important public health problem in developed countries. Preventive treatment might effect a large reduction in the incidence, but this needs to be applied selectively to those women at increased risk. Loss of bone density results in an increased risk of fractures in the classical sites of vertebrae and proximal femur. A cross sectional study of bone density measurements was carried out in these sites in British women with a modern, precise densitometric technique. Possible predictors and risk factors for bone density were assessed in these women. Bone density was measured by dual photon absorptiometry in 284 apparently healthy women volunteers aged 21 to 68. The values obtained were similar to those obtained from equivalent studies performed in women in the United States. Peak adult bone density had been attained soon after the end of linear skeletal growth. Thereafter there was some decline with age in the proximal femur, but the major fall in bone density in all sites was related to the menopause. Other factors decreasing bone density, and hence increasing risk for osteoporosis, such as low body weight, alcohol and cigarette consumption, nulliparity, lack of previous use of oral contraceptives, and lack of regular exercise, seemed to be important. None, however, could predict satisfactorily women at future risk for osteoporosis. Direct measurements of bone density in the clinically relevant sites are necessary to determine which women should received preventive treatment for postmenopausal osteoporosis. This would help make such treatment more cost effective.

Adult↗
PubMed1989

Estrogen receptors and human bone cells: immunocytochemical studies.

In this immunocytochemical study we have probed a number of human bone cell types and bone preparations for the presence of the estrogen receptor (ER) with two distinct monoclonal antibodies. Using a well-validated antibody (H222) that recognizes human ER and standard peroxidase-antiperoxidase methodology, we were unable to demonstrate nuclear staining for ER in cultured primary or transformed human bone-derived cells or in fetal bone sections. Attempts to visualize ER in osteosarcoma cell lines (TE85C and HTB96) using a silver enhancement procedure were also unsuccessful. Additionally, we failed to detect immunocytochemical staining for the progesterone receptor (using monoclonal antibody mPR1) in control or estrogen-treated human bone cell cultures. Estrogen and progesterone receptor staining was readily detectable in MCF7 human breast cancer cells. In contrast, with a monoclonal antibody that recognizes a 29 kDa cytoplasmic component (p29) closely related to human ER, we observed specific staining in all the osteoblastlike cells studied. Cytoplasmic staining for this p29 antigen was most intense in primary cultures of human bone-derived cells. It is possible that the relatively abundant but as yet undefined p29 antigen may act as a sensitive marker for the presence of ER in cells at levels below the detection limit of the anti-ER monoclonal antibody. If so, our results are consistent with the presence of ER in osteoblastlike cells at very low concentrations.

Adult↗
PubMed1989

Zoladex versus danazol in the treatment of pelvic endometriosis: effects on plasma lipid risk factors.

Plasma lipid risk markers for coronary heart disease (CHD) are influenced by sex steroid concentrations. Therapies that alter sex hormone levels have the potential to affect CHD risk. Zoladex had no effect on plasma lipids, but increased high density lipoprotein (HDL) subfraction 3, a lipoprotein of uncertain clinical significance. Danazol increased low density lipoprotein and decreased HDL concentrations to give a lipid profile associated with increased risk of CHD.

Buserelin↗
PubMed1989

A comparison of the skeletal effects of goserelin and danazol in premenopausal women with endometriosis.

The skeletal effects of two therapies for endometriosis that produce hypo-oestrogenism in 23 premenopausal women have been studied. Eleven women received goserelin 3.6 mg monthly by subcutaneous implant and 12 women received danazol 600 mg daily, orally, both for 6 months. Goserelin causes a small decline in spinal bone density, but a greater loss of density in the proximal femur. Preliminary results show no evidence that bone loss is reversible after stopping therapy. Danazol treatment is not associated with loss of bone. Prolonged or repeated courses of treatment with goserelin alone could lead to a clinically significant adverse effect on the skeleton.

Adult↗