PubMed · 3119173
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H K Genant, P Steiger, J E Block, C C Glueer, B Ettinger, S T Harris. 1987. Quantitative computed tomography: update 1987.. https://doi.org/10.1007/bf02555236
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Hormone treatment with an estrogen plus a progestagen (EPT) increases the risk of breast cancer. Both hormone activities are also induced by tibolone. In order to assess the breast safety of tibolone, it was evaluated in several pre-clinical models. The effects were inconclusive in breast cancer cell lines but, in various in vivo models, it did not stimulate the breast. In the 17,12-dimethylbenz(a)anthracene (DMBA) model, tibolone clearly inhibited the growth of breast tumors and, when given prophylactally, far less tumors developed. Ovariectomized monkeys showed no increase in the expression of the proliferation marker Ki67. The effects of tibolone and its metabolites on the steroid metabolizing enzymes in breast tissues were investigated in order to unravel its mode of action in the breast. Tibolone and its metabolites did not inhibit aromatase, but sulfatase was profoundly inhibited. The sulfated 3alpha-OH tibolone metabolite even showed irreversible inhibition of sulfatase. In addition, 17ss-hydroxysteroid dehydrogenase activities were slightly inhibited and sulfotransferase activity was stimulated at low concentrations. The consequence of these effects is that, for both endogenous estrogens and estrogenic-metabolites of tibolone, the equilibrium is preferential for the sulfated forms. The intracellular hormonal milieu tibolone and its metabolites also influence cellular homeostasis. It inhibits cell proliferation of normal breast epithelial cells and stimulates apoptosis. In this respect, tibolone behaves differently from estrogens. Clinical studies have shown that tibolone users experience less breast tenderness and do not show an increase in mammographic density as found with continuous combined EPT. The data concerning tibolone and breast cancer risk are inconclusive and require further investigation.
PURPOSE: To determine current national radiographic skeletal survey imaging practices, including migration to digital technologies, for evaluation of suspected infant abuse. MATERIALS AND METHODS: Of 155 children's health care facilities in the United States in which radiographic skeletal surveys are performed for suspected infant (<1 year old) abuse, 137 (88.4%) agreed to complete a questionnaire. Questions included facility type, imaging department volume, radiographic equipment, and details of skeletal survey imaging practices. Statistical analysis was performed with chi(2), Fisher exact, Pearson correlation, Spearman rank correlation, and Student t tests. RESULTS: One hundred seven completed questionnaires were returned. Forty-seven (43.9%) facilities used screen-film imaging; 60 (56.1%) used digital. Of screen-film users, 25 (53.2%) had already migrated or planned to migrate to digital within 1 year. Of screen-film users, 27 (60.0%) reported use of a high-detail imaging system, while 13 (21.7%) digital users employed a high-resolution technique (P < .001). Eighty-four (78.5%) facilities reported more than 10 images in their protocol, and 45 (42.0%) specified more than 15 images. Only one (0.9%) facility obtained fewer than three images. Upper extremities were imaged separately with at least two exposures in 81 (75.7%) facilities. Lower extremities were imaged separately with at least two exposures in 82 (76.6%) facilities. One hundred five (98.1%) facilities reported acquisition of lateral spinal views. CONCLUSION: Within U.S. pediatric health care facilities, most skeletal surveys in cases of suspected infant abuse include separate frontal views of the appendicular skeleton and frontal and lateral views of the axial skeleton. Imaging protocols and other image quality determinants vary widely, and as U.S. pediatric health care facilities migrate from film-based to digital imaging technology, imaging practices directly applicable to the digital environment are being retained; however, less attention is being paid to technical elements specific to digital imaging that affect high-detail image quality.
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