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To determine the optimal width of a midline posterior spinal block (MPSB) (to avoid delivering too great a dose to the cord and too small a dose to adjacent tissue), the authors determined with magnetic resonance (MR) imaging normal ranges of cord depth and width and correlated them with film dosimetric data. In 59 randomly selected patients there was a wide range for both depth and width. The average depths of the anterior and posterior surfaces of the cord were 6.7 cm +/- 1.4 and 5.4 cm +/- 1.3, respectively. The average cord width was 1.6 cm +/- 0.4. Optimal cord block width as a function of cord width was determined for a 6-MV photon beam. The optimal cord block width at the surface (half-value layer [HVL] thickness = 6) varied from 1.5 to 3.0 cm for cord widths of 0.8-2.4 cm, which correspond to two standard deviations from the average. There was no significant dependence on depth of the cord. For optimal treatment outcome, the MPSB width may have to be determined for each patient individually.  相似文献   
966.
Early influences associated with adult obesity include overfeeding leading to fat cell hyperplasia, inactivity, and faulty mechanisms of control of food intake. The first year of life is critical for the intiation of these influences; thus we need to reevaluate some of the approaches to infant feeding. Excessive weight gains in infants must be taken seriously. This article reviews related literature and makes recommendations for preventing early obesity.  相似文献   
967.
Summary Medium conditioned by human lung tissue was found to contain colony stimulating activity (CSA). This material was tested against mouse and human bone marrow as target system. Colony forming units (CFUc)from both species responded and gave rise to clonal growth in agar cultures. This colony formation was dose dependent and the relationship was a sigmoid one. Experiments to determine the molecular weight of human lung derived colony stimulating Factors brought evidence for four active molecular weight fractions with approximately 79000, 40000, 23000 and 2000 daltons. The 23000 dalton fraction activated human cells only, whereas the other fractions were active on both human and mouse bone marrow cells.  相似文献   
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The article provides an overview of the contemporary literature on the social and psychological factors which are associated with migration. Derived from the operationalisation of "migration" and an examination of the methodological peculiarities of migration research, a (transactional) stress model of migration is proposed incorporating potentially stress-eliciting influences of migration including occupational pressures, social isolation and/or family-related problems and their impact on psychological and physical health. There are inconsistencies in the findings regarding psychological health, which can in part be explained through the phenomena of the "healthy migrant effect", duration of stay in the host culture or the culture-specificity. Moreover, a discussion is provided of the extent that disorders associated with differentially stressed migrants will be manifested in the health care system. Finally, concluding remarks are offered together with a short discussion of the implication of these findings for future research and social and health policy decision-making.  相似文献   
970.
Xenobiotic metabolising enzymes modify most organic compounds into water soluble compounds. Sequence variations of these enzymes can lead to significant interindividual differences in the metabolism of xenobiotics. This review covers important sequence variations of phase I (cytochrome P450) and phase II (glutathion S-transferases, N-acetyltransferases, sulfotransferases, UDP-glucuronosyl transferases) enzymes and elucidates the significance for occupational health. At the present time, the determination of various sequence variations is not suitable for an individual risk assessment in occupational health.  相似文献   
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