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1.
Reporting of the clinical relevant dose to organs at risk (OR) and other normal tissues is crucial in trials and protocols where the aim is to assess late complications and to increase the therapeutic ratio for external beam radiotherapy. The dose distribution in normal tissues and ORs are, however, most often heterogeneous, at least when more than two opposing beams are applied. To decide the most clinical relevant dose with respect to late occurring complications is therefore not a straight forward problem. In this work we discuss what parameters characterise the dose-volume-histogram (DVH) best by calculating normal tissue complication probabilities (NTCPs) by using the Lyman model and various sets of statistical parameters drawn out from the DVHs. These NTCPs are compared to NTCPs calculated from the full DVHs, when the sets of parameters are evaluated. Our calculations indicate that the NTCP based on the Lyman model is best correlated to the Dmax value, for serially organised tissues such as the spinal cord. For organs, described largely as tissues organised in parallel, the Dmedian or Dmean of the DVH may be applied. Our calculations reveal that Dmean is the parameter of choice when Dmeclian is quite small, but when the two parameters approach each other, Dmediarl will be a better choice, using a unity volume fraction. For ORs characterised by a mixed serial and parallel functional structure, as the heart, neither Dmax, Dmedian, nor Dmi,an may predict the actual NTCP. 相似文献
2.
Cyclodextrin formulation of dorzolamide and its distribution in the eye after topical administration. 总被引:2,自引:0,他引:2
Hakon H Sigurdsson Einar Stefánsson Elínborg Gudmundsdóttir Thór Eysteinsson Margrét Thorsteinsdóttir Thorsteinn Loftsson 《Journal of controlled release》2005,102(1):255-262
Due to limited aqueous solubility of dorzolamide at physiologic pH, the pH of Trusopt eye drops (cont. 2% dorzolamide) has to be kept at about 5.65, and to increase the topical bioavailability of the drug from Trusopt the contact time of the drug with the eye surface is increased by increasing the viscosity of the eye drops to 100 cps. This low pH and high viscosity can lead to local irritation. In this study, dorzolamide hydrochloride was formulated as 2% and 4% low viscosity solutions (viscosity 3 to 5 cps) containing randomly methylated beta-cyclodextrin at pH 7.45. These formulations were evaluated in rabbits. The animals were sacrificed at various time points after topical administration of the drug and the dorzolamide concentration determined in the different parts of the eye. Trusopt was used as a reference standard. The topical availability of dorzolamide from the cyclodextrin-containing eye drops appeared to be comparable to that from Trusopt and the drug reached retina and optic nerve to give measurable concentrations for at least 8 h after administration of the eye drops. 相似文献
3.
Kinzl Geelen F. Ferrio Langsteiner Dubitscher Pfister H. Donalies Kranz G. A. Adam Koller v. Baeyer Zillig G. Rost Sjvall Einar Hahn Rubner Max H. Hofmann Bresowsky Mller H. Liguori-Hohenauer Geller Braun F. Leibbrand Tbben H. 《International journal of legal medicine》1940,33(4):353-364
International Journal of Legal Medicine - 相似文献
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Leif Ivar Havelin Nils Roar Gjerdet Ole Dankert Lunde Milan Rait Einar Sudmann 《Acta orthopaedica》1986,57(5):419-422
The wear was examined in 39 Christiansen total hip prostheses, which were removed because of mechanical loosening after being used 5 (3-11) years. In the polyacetal acetabular cups, the head had made an eccentric defect, the mean volume of which was 680 (180-3310) mm3. The mean penetration of the head into the wall of the cup was 0.8 (0.1-3.2) mm. In two additional cups the head had penetrated right through the wall of the cup. In three prostheses the polyacetal sleeve of the trunnion was so worn that the head bore directly on the stem. There was a positive correlation between wear and the time the prostheses had been used before symptoms of loosening presented. 相似文献
6.
Post-polio syndrome patients treated with intravenous immunoglobulin: a double-blinded randomized controlled pilot study 总被引:1,自引:1,他引:0
E. Farbu T. Rekand E. Vik-Mo H. Lygren N. E. Gilhus J. A. Aarli 《European journal of neurology》2007,14(1):60-65
Post-polio syndrome (PPS) is characterized by new muscle weakness, atrophy, fatigue and pain developing several years after the acute polio. Some studies suggest an ongoing inflammation in the spinal cord in these patients. From this perspective, intravenous immunoglobulin (IvIg) could be a therapeutic option. We performed a double-blinded randomized controlled pilot study with 20 patients to investigate the possible clinical effects of IvIg in PPS. Twenty patients were randomized to either IvIg 2 g/kg body weight or placebo. Primary endpoints were changes in pain, fatigue and muscle strength 3 months after treatment. Surrogate endpoints were changes in cerebrospinal fluid (CSF) cytokine levels. Secondary endpoints were pain, fatigue and isometric muscle strength after 6 months. Patients receiving IvIg reported a significant improvement in pain during the first 3 months, but no change was noted for subjective fatigue and muscle strength. CSF levels of tumour necrosis factor- α (TNF- α ) were increased compared with patients with non-inflammatory neurological disorders. In conclusion, in this small pilot study no effect was seen with IvIg treatment on muscle strength and fatigue, however IvIg treated PPS patients reported significantly less pain 3 months after treatment. TNF- α was increased in the CSF from PPS patients. The results are promising, but not conclusive because of the low number of patients studied. 相似文献
7.
Ivar Rønnestad Einar Thorsen Kåre Segadal Arvid Hope 《European journal of applied physiology》1994,69(1):32-35
In diving, pulmonary mechanical function is limited by the increased density of the gas breathed. Breathing cold and dry gas may cause an additional increase in airways resistance. We have measured forced vital capacity, forced expired volume in 1 s (FEV1) and forced midexpiratory flow rate (FEF25%–75%) before and after breathing dry or humid gas at 29–32°C during a standardized exercise intensity on a cycle ergometer at an ambient pressure of 3.7 MPa. The atmosphere was a helium and oxygen mixture with a density of 6.8 kg · m–3. Six professional saturation divers aged 26–37 years participated in the study. There were no significant differences in convective respiratory heat loss between the exposures. The mean evaporative heat loss was 67 W (range 59–89) breathing dry gas and 37 W (range 32–43) breathing humid gas, corresponding to water losses of 1.7 g · min–1 (range 1.5–2.2) and 0.9 g · min–1 (range 0.8–1.1), respectively. There was a significant reduction in FEV1 of 4.6 (SD 3.6)% (P<0.05), and in FEF25%–75% of 5.8 (SD 4.7)% (P<0.05) after breathing dry gas. There were no changes after breathing humid gas. By warming and humidifying the gas breathed in deep saturation diving bronchoconstriction may be prevented. 相似文献
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Leslie K Jacobsen Kenneth R Pugh Robert T Constable Michael Westerveld W Einar Mencl 《Neuropsychopharmacology》2007,61(1):31-40
BACKGROUND: Cannabis remains the most widely used illicit substance by adolescents and is typically consumed by this population in the context of ongoing tobacco use. Human studies have shown that both cannabis and tobacco exert effects on cognitive function; however, little is known about possible interacting effects of these drugs on brain function and cognition during adolescent development. METHODS: Verbal learning and memory were assessed in 20 adolescent users of tobacco and cannabis and 25 adolescent tobacco users with minimal history of cannabis use. Functional magnetic resonance imaging was used to examine brain function and functional connectivity while a subset of these subjects performed a verbal working memory task. RESULTS: Delayed recall of verbal stimuli deteriorated during nicotine withdrawal among cannabis users but not among comparison subjects. During high verbal working memory load, nicotine withdrawal selectively increased task-related activation of posterior cortical regions and was associated with disruption of frontoparietal connectivity in adolescent cannabis users relative to comparison subjects. CONCLUSIONS: These observations suggest that cannabis use during adolescent development may disrupt neurocircuitry supporting verbal memory formation and that deficits associated with disruption of these neurocircuits are unmasked during nicotine withdrawal. 相似文献