8 resultados para RADIATION EFFECT

em University of Queensland eSpace - Australia


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Patients with advanced cancer frequently express positive attitudes and can be unduly optimistic about the potential benefits of treatment. In order to evaluate an illusory domain in the context of advanced cancer, we developed a scale of will to live and characterized the beliefs that patients held about the curability of their cancer, and how committed they were to using alternative treatments. A measure of quality of life was used as the dependent variable in order to assess the association between these attributes. After a preliminary exploration confirmed the presence of an illusory domain, these concepts were prospectively tested in 149 ambulant patients with advanced cancer who attended for palliative systemic treatment, radiation treatment or supportive care. The scale of global quality of life was reliable (Cronbach's alpha coefficient 0.72). The distribution of the scores of will to live was skewed, with no respondent scoring poorly, and the scale was reliable (Cronbach's alpha coefficient 0.82). The scale of belief in curability showed diverse beliefs. In some cases, there was a discrepancy between respondents' beliefs in curability and what they believed to be the report by their doctors. There was also an association between a committed use of alternative treatments and a belief in the curability of the cancer (p

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Targeted treatment education for cancer patients has the potential to promote adjustment through assisting patients to participate in treatment decision making, comply with treatment regimens and cope more effectively with treatment side effects. A quasi-experimental longitudinal pre-test post-test and follow-up design was used to assess the effect of a patient education video about radiation therapy on patients' psychological distress, knowledge about radiation therapy, self-efficacy about coping with treatment and physical symptoms. Patients with head and neck (n = 26) and breast cancer (n = 66) were recruited into the study and allocated into control and intervention groups. No significant differences were found between the control and intervention groups on any of the outcome variables. However, patients in the intervention group reported high levels of satisfaction with the video and all reported that they would recommend the video to other patients preparing for radiation therapy. As well, 90% of patients in the intervention group reported that some or all of the information in the video was new to them. Education materials that have excellent face validity and that are well received by patients may fail to produce significant change using standard controlled study designs. Future research in this area may need to consider alternative paradigms for evaluating the helpfulness of such materials. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

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Leaf area growth and nitrogen concentration per unit leaf area, N-a (g m(-2) N) are two options plants can use to adapt to nitrogen limitation. Previous work indicated that potato (Solanum tuberosum L.) adapts the size of leaves to maintain Na and photosynthetic capacity per unit leaf area. This paper reports on the effect of N limitation on leaf area production and photosynthetic capacity in maize, a C4 cereal. Maize was grown in two experiments in pots in glasshouses with three (0.84-6.0 g N pot(-1)) and five rates (0.5-6.0 g pot(-1)) of N. Leaf tip and ligule appearance were monitored and final individual leaf area was determined. Changes with leaf age in leaf area, leaf N content and light-saturated photosynthetic capacity, P a,, were measured on two leaves per plant in each experiment. The final area of the largest leaf and total plant leaf area differed by 16 and 29% from the lowest to highest N supply, but leaf appearance rate and the duration of leaf expansion were unaffected. The N concentration of expanding leaves (N-a or %N in dry matter) differed by at least a factor 2 from the lowest to highest N supply. A hyperbolic function described the relation between P-max and N-a. The results confirm the 'maize strategy': leaf N content, photosynthetic capacity, and ultimately radiation use efficiency is more sensitive to nitrogen limitation than are leaf area expansion and light interception. The generality of the findings is discussed and it is suggested that at canopy level species showing the 'potato strategy' can be recognized from little effect of nitrogen supply on radiation use efficiency, while the reverse is true for species showing the 'maize strategy' for adaptation to N limitation. (c) 2004 Elsevier B.V. All rights reserved.

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The impact of ambient ultraviolet (UV)-B radiation on the endemic bryophyte, Grimmia antarctici, was studied over 14 months in East Antarctica. Over recent decades, Antarctic plants have been exposed to the largest relative increase in UV-B exposure as a result of ozone depletion. We investigated the effect of reduced UV and visible radiation on the pigment concentrations, surface reflectance and physiological and morphological parameters of this moss. Plexiglass screens were used to provide both reduced UV levels (77%) and a 50% decrease in total radiation. The screen combinations were used to separate UV photoprotective from visible photoprotective strategies, because these bryophytes are growing in relatively high light environments compared with many mosses. G. antarctici was affected negatively by ambient levels of UV radiation. Chlorophyll content was significantly lower in plants grown under near-ambient UV, while the relative proportions of photoprotective carotenoids, especially beta-carotene and zeaxanthin, increased. However, no evidence for the accumulation of UV-B-absorbing pigments in response to UV radiation was observed. Although photosynthetic rates were not affected, there was evidence of UV effects on morphology. Plants that were shaded showed fewer treatment responses and these were similar to the natural variation observed between moss growing on exposed microtopographical ridges and in more sheltered valleys within the turf. Given that other Antarctic bryophytes possess UV-B-absorbing pigments which should offer better protection under ambient UV-B radiation, these findings suggest that G. antarctici may be disadvantaged in some settings under a climate with continuing high levels of springtime UV-B radiation.

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We evaluated the effect of adjuvant whole brain irradiation (WBI) after surgery or radiosurgery for solitary brain metastases in a Phase III multicentre trial with randomization to 30-36 Gy WBI or observation. The study was closed early due to slow accrual after 19 patients (WBI 10, observation 9). There was no difference in CNS failure-free survival or overall survival between the arms. There was a trend to reduced CNS relapse with WBI (30% versus 78%, P = 0.12). Limited analysis of quality of life and neurocognitive function data revealed no evidence of difference between the arms. Our results are not inconsistent with two larger randomized trials and support the use of upfront WBI to decrease brain recurrence in this setting. (c) 2006 Elsevier Ireland Ltd. All rights reserved.