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PB Greer K Dahl MA Ebert M White C Wratten P Ostwald P Pichler JW Denham 《Journal of Medical Imaging and Radiation Oncology》2008,52(5):517-524
The aims of this study were to investigate whether intrafraction prostate motion can affect the accuracy of online prostate positioning using implanted fiducial markers and to determine the effect of prostate rotations on the accuracy of the software‐predicted set‐up correction shifts. Eleven patients were treated with implanted prostate fiducial markers and online set‐up corrections. Orthogonal electronic portal images were acquired to determine couch shifts before treatment. Verification images were also acquired during treatment to assess whether intrafraction motion had occurred. A limitation of the online image registration software is that it does not allow for in‐plane prostate rotations (evident on lateral portal images) when aligning marker positions. The accuracy of couch shifts was assessed by repeating the registration measurements with separate software that incorporates full in‐plane prostate rotations. Additional treatment time required for online positioning was also measured. For the patient group, the overall postalignment systematic prostate errors were less than 1.5 mm (1 standard deviation) in all directions (range 0.2–3.9 mm). The random prostate errors ranged from 0.8 to 3.3 mm (1 standard deviation). One patient exhibited intrafraction prostate motion, resulting in a postalignment prostate set‐up error of more than 10 mm for one fraction. In 14 of 35 fractions, the postalignment prostate set‐up error was greater than 5 mm in the anterior–posterior direction for this patient. Maximum prostate rotations measured from the lateral images varied from 2° to 20° for the patients. The differences between set‐up shifts determined by the online software without in‐plane rotations to align markers, and with rotations applied, was less than 1 mm (root mean square), with a maximum difference of 4.1 mm. Intrafraction prostate motion was found to reduce the effectiveness of the online set‐up for one of the patients. A larger study is required to determine the magnitude of this problem for the patient population. The inability in the current software to incorporate in‐plane prostate rotations is a limitation that should not introduce large errors, provided that the treatment isocentre is positioned near the centre of the prostate. 相似文献
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Decreased plasma orexin-A levels in obese individuals 总被引:10,自引:0,他引:10
Adam JA Menheere PP van Dielen FM Soeters PB Buurman WA Greve JW 《International journal of obesity (2005)》2002,26(2):274-276
Orexin-A and -B stimulate appetite and food intake in rats. Orexins and orexin receptors are present in the hypothalamus as well as the enteric nervous system, the pancreas and the gut. The presence of orexins in peripheral blood, however, has not yet been reported. To determine whether orexin-A is present in human plasma and is related to body weight, we measured plasma orexin-A and leptin levels in a population with a body mass index (BMI) range from 19.8 to 59 kg/m(2). Plasma orexin-A levels correlated negatively and plasma leptin levels correlated positively with BMI. In obese and morbidly obese individuals, orexin-A levels were significantly lower and leptin levels were significantly higher when compared to normal. Our results support previous data suggesting that orexin-A acts also in a peripheral manner. The fact that lower levels of plasma orexin-A are present in obese individuals suggests that it is involved in the regulation of human energy metabolism. 相似文献
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JW Gregory SA Greene RT Jung CM Scrimgeour MJ Rennie 《Archives of disease in childhood》1993,68(2):205-209
Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months. 相似文献
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Age-related postural deficits elicit compensatory mechanisms such as ankle dorsiflexion in the elderly. To gain further insight into this problem, the ability to match an ankle angle during quiet stance was studied in 12 elderly and 12 young subjects. Following an initial single limb angular perturbation presented in the ±4° range, a subject had to return a tilt platform to level, as determined by the nonperturbed limb. Elderly subjects exhibited significant positive (0.9°) over-shoot of the level position, in contrast to young subjects who matched ankle angle with a mean error of −0.1°. The elderly group also exhibited an increase in positioning error for angular displacements in the range between −1 and +1°. The results document age-related postural changes in ankle positioning which might affect postural stability in older adults. 相似文献