| 1. |
|
|
| 2. |
|
|
| 3. |
- Burnet, N G, et al.
(författare)
-
Describing patients' normal tissue reactions: concerning the possibility of individualising radiotherapy dose prescriptions based on potential predictive assays of normal tissue radiosensitivity. Steering Committee of the BioMed2 European Union Concerted Action Programme on the Development of Predictive Tests of Normal Tissue Response to Radiation Therapy.
- 1998
-
Ingår i: International journal of cancer. Journal international du cancer. - 0020-7136. ; 79:6, s. 606-13
-
Tidskriftsartikel (refereegranskat)abstract
- Clinical radiotherapeutic doses are limited by the tolerance of normal tissues. Patients given a standard treatment exhibit a range of normal tissue reactions, and a better understanding of this individual variation might allow for individualisation of radiotherapeutic prescriptions, with consequent improvement in the therapeutic ratio. At present, there is no simple way to describe normal tissue reactions, which hampers communication between clinic and laboratory and between groups from different centres. There is also no method for comparing the severity of reactions in different normal tissues. This arises largely because there is no definition of a "normal" reaction, an "extreme" reaction or the particular term "over-reactor" (OR). This report proposes definitions for these terms, as well as a simple terminology for describing normal tissue reactions in patients having radiotherapy. The "normal" range represents the individual variation in normal tissue reactions amongst large numbers of patients treated in the same way which is within clinically acceptable limits. The term "OR" is applied to an individual whose reaction is more severe than the normal range but also implies that this forced a major change in the radiotherapeutic prescription or that the reactions were very severe or fatal. A "severe OR" would develop serious problems with a typical radical dose, while an "extreme OR" would have such difficulties at a much lower dose. To describe the normal range, a numerical scale is suggested, from 1 to 5, resistant to sensitive. The term "highly radiosensitive" (HR) is suggested for category 5. An "informal" relative scale, as suggested here, is quick and simple. It should allow comparison between different hospitals, compensate for differences in radiotherapeutic dose and technique and allow comparison of reactions between different anatomical sites. It should be adequate for discriminating patients at the extremes of the normal range from those at the centre. It is hoped that the definitions and terminology proposed here will aid communication in the field of predictive testing of normal tissue radiosensitivity.
|
|
| 4. |
- Burnet, N G, et al.
(författare)
-
Normal tissue radiosensitivity--how important is it?
- 1996
-
Ingår i: Clinical oncology (Royal College of Radiologists (Great Britain)). - 0936-6555. ; 8:1, s. 25-34
-
Tidskriftsartikel (refereegranskat)abstract
- The success of radiotherapy in eradicating tumours depends on the total radiation dose, but what limits this dose is the tolerance of the normal tissues within the treatment volume. Selection of the appropriate dose for all patients is based on a balance between minimising the incidence of severe normal tissue complications and maximizing the probability of local control. In patients treated to the same radical dose, a wide range of reactions is seen; in many clinical situations, radical doses are limited by the minority of patients whose normal tissues are particularly sensitive. Clinical studies of radiotherapy reactions have demonstrated that a large part of the spectrum of normal tissue reactions, perhaps as much as 80%, is due to differences in individual normal tissue sensitivity. This suggests that it might be possible to measure this sensitivity and to change treatment accordingly. The main objective of normal tissue sensitivity testing is to permit dose escalation without increased normal tissue complication rates in patients with more resistant normal tissues. Calculations suggest that the most "resistant' 40% of patients could be dose escalated by 17%-18%, which is likely to be associated with significant gains in local control, perhaps by as much as 34%-36%; this should translate into an increase in overall survival. It should also be possible to identify those relatively few patients who suffer serious normal tissue morbidity with conventional doses. Thus, if successful, predictive testing of normal tissue response should improve the therapeutic ratio of radiotherapy.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Ivancev, Krassi, et al.
(författare)
-
Abdominal aortic aneurysms: experience with the Ivancev-Malmo endovascular system for aortomonoiliac stent-grafts
- 1997
-
Ingår i: Journal of Endovascular Surgery. - 1074-6218. ; 4:3, s. 242-251
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To describe a component-based aortomonoiliac stent-graft system and the first clinical results achieved with this device in endovascular abdominal aortic aneurysm (AAA) repair. METHODS: From November 1993 to October 1996, 45 patients aged 60 to 86 years underwent endoluminal exclusion of true AAAs (median diameter 60 mm) involving the common iliac arteries (median diameter 16 mm right and 15 mm left) using unilimb stent-grafts deployed with the Iancev-Malmo system. RESULTS: Six immediate conversions occurred in the beginning of the series due to endografts that were too short. Complications, including 2 inadvertent renal artery occlusions, 7 kinked grafts, 6 iliac artery dissections, and 3 perioccluder leaks, were prominent features in the first 15 patients. Five patients died in the postoperative period, four of whom were nonsurgical candidates. There were five significant stent-graft migrations: one 3 weeks after surgery due to mechanical injury of the proximal stent and four after 1 year owing to continuous dilation of a wide proximal neck, stent-graft placement in a conical, thrombus-lined proximal neck, and two instances of proximal extension separation from the main graft. Translumbar aneurysm perfusion required embolization in 3 patients. CONCLUSIONS: Despite early complications associated with a learning curve, exclusion of large AAAs using unilimb stent-grafts is feasible. Strict inclusion criteria are necessary in order to improve mortality among nonsurgical candidates and minimize the risk for late migration.
|
|
| 8. |
- Larsson, Gunilla, et al.
(författare)
-
Kinetic Characterization of dUTPase from Escherichia coli
- 1996
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 271:39, s. 24010-24016
-
Tidskriftsartikel (refereegranskat)abstract
- The enzyme dUTPase catalyzes the hydrolysis of dUTP to dUMP and pyrophosphate, thereby preventing a deleterious incorporation of uracil into DNA. The best known dUTPase is that from Escherichia coli, which, like the human enzyme, consists of three identical subunits. In the present work, the catalytic properties of the E. coli dUTPase were investigated in the pH range 5-11. The enzyme was found to be highly specific for dUTP and discriminated both base and sugar as well as the phosphate moiety (bound dUDP was not hydrolyzed). The second best substrate among the nucleotides serving as building blocks for DNA was dCTP, which was hydrolyzed an astonishing 105 times less efficiently than dUTP, a decline largely accounted for by a higher Km for dCTP. With dUTP·Mg as substrate, kcat was found to vary little with pH and to range from 6 to 9 s1. Km passed through a broad minimum in the neutral pH range with values approaching 107 M. It increased with deprotonation of the uracil moiety of dUTP and showed dependence on two ionizations in the enzyme, exhibiting pKa values of 5.8 and 10.3. When excess dUTPase was reacted with dUTP·Mg at pH 8, the two protons transferred to the reaction medium were released in a concerted mode after the rate-limiting step. The Mg2+ ion enhances binding to dUTPase of dUTP by a factor of 100 and dUDP by a factor of 10. Only one enantiomer of the substrate analog 2-deoxyuridine-5-(-thio)-triphosphate was hydrolyzed by the enzyme. These results are interpreted to favor a catalytic mechanism involving magnesium binding to the -phosphate, rate-limiting hydrolysis by a shielded and activated water molecule and a fast ordered desorption of the products. The results are discussed with reference to recent data on the structure of the E. coli dUTPase·dUDP complex.
|
|
| 9. |
- Lundgren, Anna Karin, et al.
(författare)
-
Augmentation of skull bone using a bioresorbable barrier supported by autologous bone grafts. An intra-individual study in the rabbit.
- 1997
-
Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:2, s. 90-5
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this experimental investigation was to compare the effect of using autologous particulate bone grafts with and without a bioresorbable barrier covering for augmentation of the rabbit skull bone. For this purpose, bilateral, circular, 8 mm wide and 1 mm deep skull bone defects were prepared and overfilled with particulate bone grafts. The grafts placed in the test sites were covered with a bioresorbable barrier (Guidor Matrix Barrier). The grafts placed in the control sites were covered only by the repositioned, cutaneous flap. 12 weeks later, the animals were sacrificed, the experimental sites were defleshed and the height and volume of the augmented bone in the test and control sites were measured clinically. Histologically, morphometrical measurements of the bone tissue were performed in decalcified vertical cross-sections of the experimental sites. Statistically significant differences were found in favour of the coverage of the bone graft particles with the barrier, both with respect to the height and the volume of the augmented bone.
|
|
| 10. |
- Lundgren, Anna Karin, et al.
(författare)
-
Bone augmentation at titanium implants using autologous bone grafts and a bioresorbable barrier. An experimental study in the rabbit tibia.
- 1997
-
Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 8:2, s. 82-9
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present investigation was to compare the effect of using autologous bone particles covered with a bioresorbable matrix barrier with the use of bone particles alone on bone augmentation at titanium implants installed in the rabbit tibia. Two Brånemark System implants, one in each tibia, were inserted in each of 9 rabbits in such a way that 5 threads were not covered with bone. Autologous bone particles were harvested from the skull and placed over the exposed implant surfaces on each tibia. The bone graft on one tibia was covered with a Guidor Matrix Barrier, while the bone graft on the other tibia served as a control. After a healing period of 12 weeks, the animals were sacrificed and specimens taken for histomorphometrical analyses. The analyses showed that a significantly larger volume of augmented bone tissue had formed at the test sites. There were, however, no differences in the amount of mineralized bone. In fact, the difference in tissue volume was due to an increased amount of bone marrow at the test sites. The degree of mineralized bone to implant contact as well as the degree of mineralized bone within the threads at the test implants were similar to that at the controls. In conclusion, it was found that the coverage of particulate autologous bone grafts with a bioresorbable barrier resulted in a larger volume of augmented bone than the use of bone grafts not covered with a barrier.
|
|
