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| 2. |
- Hopewell, J W, et al.
(författare)
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Time factor for acute tissue reactions following fractionated irradiation: a balance between repopulation and enhanced radiosensitivity.
- 2003
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Ingår i: International journal of radiation biology. - 0955-3002. ; 79:7, s. 513-24
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Tidskriftsartikel (refereegranskat)abstract
- Experimental data for acute radiation-induced skin reactions are reviewed. These show that for dose fractionation schedules with gaps, repopulation is initiated after a lag period. After this lag period, the isoeffective dose for a given level of skin reaction first increases rapidly, but then slows. The timing of the lag period is related to the total turnover time of the tissue under investigation and, for example, is shorter in rodent skin than in pig or human skin. At the point when accelerated repopulation is initiated, there is a major shortening of the turnover time of the target cell population. At this time, there is evidence, for a short period, for an increase in radiosensitivity of the surviving stem cells in a number of acutely responding normal tissues. This effect is clearly illustrated by the results of experiments using sequential dose fractionation schedules. Prolongation of the schedule from 'short' to schedules that include irradiation over the period when the cell turnover is accelerated is associated with a marked increase in tissue radiosensitivity. Clinically, this is best illustrated by a comparison of the effects of accelerated fractionation schedules, involving multiple fractions/day, with daily fractionation schedules. The increase in radiosensitivity produced by the prolongation of the treatment from 2 to 4-5 weeks was equivalent to > or =1 Gy day(-1). Comparable findings were obtained from animal studies. In the oral mucosa of mice, the initiation of accelerated cell proliferation in surviving cells is associated with the loss of dose sparing by subsequent dose fractionation due to the loss of the capacity to repair sublethal damage. Studies in pig and human skin have indicated that increased radiosensitivity is associated with a loss of cells in the G1 phase of the cell cycle. A collation of these two sets of findings suggests that the repair of sublethal damage takes place over this phase of the cell cycle. One clinical implication of these findings is that the alpha/beta ratio for acute skin reaction changes with the length of the overall treatment time; it is approximately 4.0 Gy for 'short' fractionation schedules that avoid any shortening of the cell cycle time. This increases to 11.2-13.3 Gy for schedules given in 3-4 weeks and to approximately 35 Gy for schedules given in 5-6 weeks. Results for pig skin were in total agreement with those for human skin.
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| 3. |
- Matsumoto, Taro, et al.
(författare)
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p38 MAP kinase negatively regulates endothelial cell survival,proliferation, and differentiation in FGF-2-stimulated angiogenesis
- 2002
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Ingår i: Journal of Cell Biology. - 0021-9525 .- 1540-8140. ; 156:1, s. 149-160
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Tidskriftsartikel (refereegranskat)abstract
- The p38 mitogen-activated protein kinase (p38) is activated in response to environmental stress and inflammatory cytokines. Although several growth factors, including fibroblast growth factor (FGF)-2, mediate activation of p38, the consequences for growth factor-dependent cellular functions have not been well defined. We investigated the role of p38 activation in FGF-2-induced angiogenesis. In collagen gel cultures, bovine capillary endothelial cells formed tubular growth-arrested structures in response to FGF-2. In these collagen gel cultures, p38 activation was induced more potently by FGF-2 treatment compared with that in proliferating cultures. Treatment with the p38 inhibitor SB202190 enhanced FGF-2-induced tubular morphogenesis by decreasing apoptosis, increasing DNA synthesis and cell proliferation, and enhancing the kinetics of cell differentiation including increased expression of the Notch ligand Jagged1. Overexpression of dominant negative mutants of the p38-activating kinases MKK3 and MKK6 also supported FGF-2-induced tubular morphogenesis. Sustained activation of p38 by FGF-2 was identified in vascular endothelial cells in vivo in the chick chorioallantoic membrane (CAM). SB202190 treatment enhanced FGF-2-induced neovascularization in the CAM, but the vessels displayed abnormal features indicative of hyperplasia of endothelial cells. These results implicate p38 in organization of new vessels and suggest that p38 is an essential regulator of FGF-2-driven angiogenesis.
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| 4. |
- Mattsson, Sören, et al.
(författare)
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Swedish Cancer Society radiation therapy research investigation
- 2002
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 41:7-8, s. 596-603
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Tidskriftsartikel (refereegranskat)abstract
- In an investigation by the Swedish Cancer Society, the present status, critical issues and future aspects and prospects were described by an expert group for each of nine major areas of radiation research. A summary of the investigation is presented in this report. A more extensive summary (in Swedish) can be found at www.Cancerfonden.se. It is concluded that radiation therapy plays an increasingly important role in curative and palliative tumour treatment and presents a considerable challenge to research. Several suggestions are made that could improve the possibilities for high-quality radiation therapy research in Sweden.
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| 6. |
- Qvarnström, Olov Fredrik, et al.
(författare)
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DNA double strand break quantification in skin biopsies.
- 2004
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 0167-8140. ; 72:3, s. 311-7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Following induction of double strand breaks the histone H2AX is rapidly phosphorylated at regions flanking the breaks resulting in nuclear gamma H2AX foci. The purpose of this study was to use this endogenous signalling system to quantify the in vivo response to radiation in normal tissue. PATIENTS AND METHODS: Skin biopsies were taken from prostate cancer patients undergoing radiotherapy with a curative intent. Biopsies were taken at locations corresponding to 5 different doses in the range below 1.1 Gy per fraction. Biopsies were taken from patients 30 min following the first fraction and then once again following the fraction given after the first weekend break in the treatment course. The DNA double strand breaks were visualised as gamma H2AX foci using immunohistochemistry. Images were acquired using a CCD-camera and a fluorescence microscope and the gamma H2AX foci were quantified using digital image analysis including the basic procedures of top-hat transformation, threshold setting and labelling. RESULTS: Repeated assessments of the biopsies showed a high reproducibility in quantifying the number of foci per DNA area of the nucleated cells in epidermis. The reproducibility was equally good for the two biopsy occasions. A linear dose response was observed for the epidermis in the dose region 0-1 Gy. CONCLUSIONS: We have established a method to measure the relative amount of DNA double strand breaks by detecting gamma H2AX foci in patients exposed to radiotherapy. The method provides a tool to study induction and repair of DNA double strand breaks and has the potential to predict individual radiosensitivity.
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| 8. |
- Tannock, Ian F., et al.
(författare)
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Docetaxel plus prednisone or mitoxantrone plus prednisone for advanced prostate cancer
- 2004
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 351:15, s. 1502-12
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Mitoxantrone plus prednisone reduces pain and improves the quality of life in men with advanced, hormone-refractory prostate cancer, but it does not improve survival. We compared such treatment with docetaxel plus prednisone in men with this disease. METHODS: From March 2000 through June 2002, 1006 men with metastatic hormone-refractory prostate cancer received 5 mg of prednisone twice daily and were randomly assigned to receive 12 mg of mitoxantrone per square meter of body-surface area every three weeks, 75 mg of docetaxel per square meter every three weeks, or 30 mg of docetaxel per square meter weekly for five of every six weeks. The primary end point was overall survival. Secondary end points were pain, prostate-specific antigen (PSA) levels, and the quality of life. All statistical comparisons were against mitoxantrone. RESULTS: As compared with the men in the mitoxantrone group, men in the group given docetaxel every three weeks had a hazard ratio for death of 0.76 (95 percent confidence interval, 0.62 to 0.94; P=0.009 by the stratified log-rank test) and those given weekly docetaxel had a hazard ratio for death of 0.91 (95 percent confidence interval, 0.75 to 1.11; P=0.36). The median survival was 16.5 months in the mitoxantrone group, 18.9 months in the group given docetaxel every 3 weeks, and 17.4 months in the group given weekly docetaxel. Among these three groups, 32 percent, 45 percent, and 48 percent of men, respectively, had at least a 50 percent decrease in the serum PSA level (P<0.001 for both comparisons with mitoxantrone); 22 percent, 35 percent (P=0.01), and 31 percent (P=0.08) had predefined reductions in pain; and 13 percent, 22 percent (P=0.009), and 23 percent (P=0.005) had improvements in the quality of life. Adverse events were also more common in the groups that received docetaxel. CONCLUSIONS: When given with prednisone, treatment with docetaxel every three weeks led to superior survival and improved rates of response in terms of pain, serum PSA level, and quality of life, as compared with mitoxantrone plus prednisone.
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