| 31. |
- Andisheh, Bahram, 1967-
(författare)
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Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New methods of high dose delivery, such as intensity modulated radiation therapy (IMRT), stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), hadron therapy, tomotherapy, etc., all make use of a few large fractions. To improve these treatments, there are three main directions: (i) improving physical dose distribution, (ii) optimizing radiosurgery dose-time scheme and (iii) modifying dose response of tumors or normal tissues.Different radiation modalities and systems have been developed to deliver the best possible physical dose to the target while keeping radiation to normal tissue minimum. Although applications of radiobiological findings to clinical practice are still at an early stage, many studies have shown that sublethal radiation damage repair kinetics plays an important role in tissue response to radiation.The purpose of the present thesis is to show how the above-mentioned directions could be used to improve treatment outcomes with special interest in radiation modalities and dose-time scheme, as well as radiobiological modeling. Also for arteriovenous malformations (AVM), the possible impact of AVM network angiostructure in radiation response was studied.
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| 32. |
- Andisheh, Bahram, 1967-, et al.
(författare)
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Vascular structure and binomial statistics for response modeling in radiosurgery of cerebral arteriovenous malformations
- 2010
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 55:7, s. 2057-2067
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Tidskriftsartikel (refereegranskat)abstract
- Radiation treatment of arteriovenous malformations (AVMs) has a slow and progressive vaso-occlusive effect. Some studies suggested the possible role of vascular structure in this process. A detailed biomathematical model has been used, where the morphological, biophysical and hemodynamic characteristics of intracranial AVM vessels are faithfully reproduced. The effect of radiation on plexiform and fistulous AVM nidus vessels was simulated using this theoretical model. The similarities between vascular and electrical networks were used to construct this biomathematical AVM model and provide an accurate rendering of transnidal and intranidal hemodynamics. The response of different vessels to radiation and their obliteration probability as a function of different angiostructures were simulated and total obliteration was defined as the probability of obliteration of all possible vascular pathways. The dose response of the whole AVM is observed to depend on the vascular structure of the intra-nidus AVM. Furthermore, a plexiform AVM appears to be more prone to obliteration compared with an AVM of the same size but having more arteriovenous fistulas. Finally, a binomial model was introduced, which considers the number of crucial vessels and is able to predict the dose response behavior of AVMs with a complex vascular structure.
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| 33. |
- Annuk, Margus, et al.
(författare)
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Cyclooxygenase inhibition improves endothelium-dependent vasodilatation in patients with chronic renal failure
- 2002
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Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 17:12, s. 2159-2163
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Some studies have demonstrated beneficial effects of L-arginine as a substrate for nitric oxide synthesis, and diclofenac as an inhibitor of cyclooxygenase (COX)-derived vasoconstrictive agents on vascular responses in humans during several pathological conditions. The aim of the present study was to investigate the acute effects of L-arginine and diclofenac on endothelium-dependent vasodilatation (EDV) and endothelium-independent vasodilatation (EIDV) in patients with chronic renal failure (CRF). METHODS: Effects of L-arginine and diclofenac on EDV and EIDV were measured in 15 patients with CRF and in 15 healthy controls by means of forearm blood flow measurements with venous occlusion plethysmography during local intra-arterial infusions of methacholine (2 and 4 micro g/min evaluating EDV) and sodium nitroprusside (5 and 10 micro g/min evaluating EIDV). RESULTS: L-Arginine infusion increased methacholine-induced vasodilatation both in patients with CRF and healthy controls. Diclofenac infusion increased methacholine-induced vasodilatation only in patients with CRF. There was no significant change in nitroprusside-induced vasodilatation after L-arginine and diclofenac infusions both in patients with CRF and healthy controls. CONCLUSIONS: These results suggest that COX inhibition reduces the levels of a prostanoid-derived vasoconstrictive agent contributing to the impaired EDV in patients with CRF, while in this age group L-arginine improves EDV regardless of renal function.
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| 34. |
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| 35. |
- Annuk, Margus, et al.
(författare)
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Endothelial function, CRP and oxidative stress in chronic kidney disease
- 2005
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Ingår i: JN. Journal of Nephrology (Milano. 1992). - 1121-8428 .- 1724-6059. ; 18:6, s. 721-726
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chronic kidney disease (CKD) is associated with increased morbidity and mortality in cardiovascular disease (CVD). Apart from traditional risk factors, chronic inflammation, oxidative stress, malnutrition and endothelial dysfunction are important in CVD development in renal patients. Our aim was to investigate the relationship between high sensitivity C-reactive protein (CRP), endothelium dependent vasodilation (EDV) and oxidative stress markers in patients with CKD K/DOQI stage 3-5.METHODS: Measurements of CRP, conjugated dienes (CD), lipid hydroperoxide (LOOH), oxidized low density lipoprotein,glutathione and albumin were performed in 44 consecutive patients with CKD stage 3-5. EDV was measured by methacholine infusion in the brachial artery and venous occlusion plethysmography.RESULTS: Patients with high CRP had significantly lower glomerular filtration rates and albumin, but increased LOOH and CD. In multiple regression analysis, only LOOH and CD remained significant. Patients with poor EDV had increased urea and lower glutathione (GSH). In multiple regression analysis, GSH and urea were independently related to EDV. No correlation was found between CRP and endothelial function.CONCLUSION: CRP was related to lipid peroxidation, while endothelial function was related to intracellular oxidative stress in patients with CKD. CRP and EDV were unrelated to each other. Therefore, CRP and endothelial function could provide complementary prognostic information regarding future cardiovascular disorders in renal patients.
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| 36. |
- Annuk, Margus, et al.
(författare)
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Erythropoietin impairs endothelial vasodilatory function in patients with renal anemia and in healthy subjects
- 2006
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Ingår i: Nephron. Clinical practice. - : S. Karger AG. - 1660-8151 .- 2235-3186 .- 1660-2110. ; 102:1, s. c30-c34
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aim: The mechanisms underlying the aggravation or development of hypertension frequently seen during treatment of renal anemia with epoetins are not fully elucidated. The aim of the present study was to investigate the effects of epoetin alfa on endothelial vasodilatory function in patients with renal anemia and in healthy subjects. Methods: Eighteen preuremic patients with anemia (GFR 23.4 ± 11 SD ml/min, Hb 101 ± 8 g/l) and 10 healthy subjects underwent evaluation of endothelium-dependent vasodilation (EDV) and endothelium-independent vasodilation (EIDV) by means of forearm blood flow (FBF) measurements with venous occlusion plethysmography during local intra-arterial infusions of methacholine (MCh, evaluating EDV) and sodium nitroprusside (SNP, evaluating EIDV). These investigations were performed before and 30 min after an intravenous injection of epoetin alfa (10,000 IU). Ten healthy subjects underwent the same procedure with the exception that saline were given instead of epoetin. The patients were treated with epoetin alfa subcutaneously for 12-19 weeks and revaluated when Hb exceeded 120 g/l. Results: EDV was attenuated after the epoetin injection in both renal patients and healthy subjects. This impairment persisted after anemia had been treated. EDIV and blood pressure remained constant. Saline had no effect on the variables measured. Conclusion: Our results indicate that epoetin alfa impairs endothelial function in renal patients and healthy subjects which may have an impact on vascular complications.
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| 37. |
- Annuk, Margus, et al.
(författare)
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Impaired endothelium-dependent vasodilatation in renal failure in humans
- 2001
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Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 16:2, s. 302-306
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The main causes of death in patients with chronic renal failure (CRF) are cardiovascular complications. The aim of the present study was to compare endothelium-dependent vasodilatation (EDV) in patients with chronic renal failure with a control population controlling for hypertension, diabetes mellitus and hypercholesterolaemia. METHODS: Fifty-six patients with moderate CRF (mean creatinine clearance 29.4 ml/min/1.73 m(2)) underwent evaluation of EDV and endothelium-independent vasodilatation (EIDV) by means of forearm blood flow (FBF) measurements with venous occlusion plethysmography during local intra-arterial infusions of methacholine (Mch, 2 and 4 microg/min evaluating EDV) and sodium nitroprusside (SNP, 5 and 10 microg/min evaluating EIDV). Fifty-six control subjects without renal impairment underwent the same investigation. RESULTS: Infusion of Mch increased FBF significantly less in patients with renal failure than in controls (198 vs 374%, P<0.001), whereas no significant difference was seen regarding the vasodilatation induced by SNP (278 vs 269%). The differences in EDV between the groups were still significant after controlling for hypertension, blood glucose, and serum cholesterol in multiple regression analysis (P<0.001). EDV was related to serum creatinine (r=-0.37, P<0.01), creatinine clearance (r=0.45, P<0.005) and to serum triglyceride levels (r=-0.29, P<0.005) in the CRF group. CONCLUSIONS: Patients with moderate CRF have an impaired EDV even after correction for traditional cardiovascular risk factors and this impairment is related to the degree of renal failure.
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| 38. |
- Annuk, Margus, et al.
(författare)
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Oxidative stress and endothelial function in chronic renal failure
- 2001
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673 .- 1533-3450. ; 12:12, s. 2747-2752
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study aimed to investigate the relationship between oxidative stress and endothelium-dependent vasodilation in patients with chronic renal failure (CRF). Thirty-seven patients with CRF underwent evaluation of endothelium-dependent vasodilation and endothelium-independent vasodilation by means of forearm blood flow measurements with venous occlusion plethysmography during local intra-arterial infusions of methacholine (evaluating endothelium-dependent vasodilation) and sodium nitroprusside (evaluating endothelium-independent vasodilation). Lag phase of lipoprotein fraction to oxidation, total antioxidative activity, diene conjugates, thiobarbituric acid reactive substances, lipid hydroperoxide, reduced glutathione (GSH), oxidized GSH (GSSG), and the GSH redox ratio (GSSG/GSH) were all measured as markers of oxidative stress. Two groups of healthy subjects (61 and 37 subjects, respectively) were used as controls. In one group, oxidative stress markers were measured, whereas endothelium-dependent vasodilation and endothelium-independent vasodilation were assessed in the other group. Compared with controls, the patients with renal insufficiency had an impaired endothelium-dependent vasodilation, a shorter lag phase of lipoprotein fraction, and higher levels of diene conjugates, lipid hydroperoxide, and GSSG levels. The GSSG/GSH ratio was lower in patients with CRF. Endothelium-dependent vasodilation was positively correlated with total antioxidative activity (r = 0.41, P = 0.016), GSH (r = 0.44, P < 0.0098), and lag phase of LDL (r = 0.35, P = 0.036) and negatively correlated with GSSG (r = -0.40, P < 0.018), GSSG/GSH (r = -0.47, P = 0.0057), and diene conjugates (r = -0.53 P < 0.0015) in patients with CRF. These results show that an impaired endothelium vasodilation function and oxidative stress are related to each other in patients with CRF.
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| 39. |
- Anundi, Helena, et al.
(författare)
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Air and biological monitoring of solvent exposure during grafitti removal
- 2000
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 73:8, s. 561-569
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The principal aim of the study was to estimate the level of exposure to organic solvents of graffiti removers, and to identify the chemicals used in different cleaning agents. A secondary objective was to inform about the toxicity of various products and to optimise working procedures.METHODS: Exposure to organic solvents was determined by active air sampling and biological monitoring among 38 graffiti removers during an 8-h work shift in the Stockholm underground system. The air samples and biological samples were analysed by gas chromatography. Exposure to organic solvents was also assessed by a questionnaire and interviews.RESULTS: Solvents identified were N-methylpyrrolidone (NMP), dipropylene glycol monomethyl ether (DPGME), propylene glycol monomethyl ether (PGME), diethylene glycol monoethyl ether (DEGEE), toluene, xylene, pseudocumene, hemimellitine, mesitylene, ethylbenzene, limonene, nonane, decane, undecane, hexandecane and gamma-butyrolactone. The 8-h average exposures [time-weighted average (TWA)] were below 20% of the Swedish permissible exposure limit value (PEL) for all solvents identified. In poorly ventilated spaces, e.g. in elevators etc., the short-term exposures exceeded occasionally the Swedish short-term exposure limit values (STEL). The blood and urine concentrations of NMP and its metabolites were low. Glycol ethers and their metabolites (2-methoxypropionic acid (MPA), ethoxy acetic acid (EAA), butoxy acetic acid (BAA), and 2-(2-methoxyethoxy) acetic acid (MEAA)) were found in low concentrations in urine. There were significant correlation between the concentrations of NMP in air and levels of NMP and its metabolites in blood and urine. The use of personal protective equipment, i.e. gloves and respirators, was generally high.CONCLUSIONS: Many different cleaning agents were used. The average exposure to solvents was low, but some working tasks included relatively high short-term exposure. To prevent adverse health effects, it is important to inform workers about the health risks and to restrict the use of the most toxic chemicals. Furthermore, it is important to develop good working procedures and to encourage the use of personal protection equipment.
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| 40. |
- Arvidsson, Per I., et al.
(författare)
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Öppenheten förstör chansen till patent
- 2015
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Ingår i: Svenska dagbladet. - Stockholm : Svenska Dagbladet AB & Co.. - 2001-3868.
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Tidskriftsartikel (populärvet., debatt m.m.)
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