The objective of this study was to assess the effects of ascorbic acid supplementation, 500 mg twice daily in the treatment of pressure ulcers as an adjunct to standardized treatment.
The design consisted of a multicenter blinded randomized trial. The control group received 10 mg of ascorbic acid twice daily.
Patients from 11 nursing homes and 1 hospital participated.
Main outcome measures included wound survival, healing rates of wound surfaces, and clinimetric changes over 12 weeks.
Eighty-eight patients were randomized. Intention-to-treat analysis showed that the wound closure probability per unit time (i.e., the closure rate) was not higher in the intervention group than in the control group (Cox hazard ratio of 0.78 [90% precision interval, 0.44–1.39]). Mean absolute healing rates were 0.21 and 0.27 cm2/week in the intervention and control group, respectively (PI of the adjusted difference: −0.17 to 0.13). Relative healing rates and healing velocities did not show favorable results of ascorbic acid supplementation, either. A panel scored slides of the ulcers with a report mark between 1 (bad) and 10 (excellent). The improvement was 0.45 and 0.72 points per week in the intervention and control group, respectively (PI of the adjusted difference: −0.50 to 0.20). With another clinimetric index we could not show any differences, either.
These data do not support the idea that ascorbic acid supplementation (500 vs. 10 mg twice daily) speeds up the healing of pressure ulcers. 相似文献
Object: Diesel soot has been recognized as probably carcinogenic to humans. Elemental carbon (also called black carbon) in soot
is considered at the moment as the most significant surrogate to be measured for assessing the exposure to this pollutant.
Its analysis is done by combustion in an oven and determination of the CO2 formed, after elimination of the organic fraction of the soot by heating and/or by solvent extraction. The analysis allows
determination of both fractions of the soot: “elemental carbon” (EC) and organic carbon␣(OC). The sum of EC and OC is called
TC (total carbon). Method: An informal European coordination group organized two round robin tests on filter samples collected from diluted diesel
emissions. The first round (RRT1) was performed on 13 different samples analyzed by ten laboratories. The range of loading
was 2.5 to 150 μg/cm2 of EC. No evaluation of the precision within laboratories could be made since each laboratory gave only one result per sample.
Therefore a second round (RRT2) was organized with two samples and a blank filter sent in several portions to 11 laboratories.
It should be stressed that each laboratory used its own method and that no standardization was planned at this stage. Results: Results of RRT1 showed that the coefficient of variation between laboratories decreased with higher loading and was around
10% to 15% for EC above about 20 μg/cm2. Dispersion of the results varied and it appeared that the way OC is removed from the soot is probably the most important
factor of influence. The correlation between the laboratories was good as a whole but some systematic differences could be
detected. Besides the different techniques to remove the organic carbon, the pretreatment of the filter by HCl (either as
a vapor or as a solution) to remove the inorganic carbonates (potential interference sources), is probably also a significant
factor of influence in the dispersion of the results between laboratories. It is not yet clear from these results whether
the “environmental” laboratories give different results from the “occupational” laboratories, but it is clear that their objectives
differ since for the “environmentalists”, EC is not a specific marker of diesel immissions, in contrast to the “occupationalists”.
Conclusion: It can be concluded that, although significant differences exist between laboratories they can be attributed mainly to the
narrow distribution of the results within a single laboratory, and that the overall agreement of the results for EC and TC
is fairly good. These results obtained with pure diesel engine emissions, should be complemented by field samples, but they
have already achieved relevant findings in the performance of the procedures used to assess exposure to diesel soot.
Received: 30 December 1996 / Accepted: 21 February 1997 相似文献
Six numerical integration algorithms based on linear and log trapezoidal methods as well as four cubic-spline methods were proposed for estimation of area under the curve (AUC). These six different algorithms were implemented using IMSL/IDLTM command language and evaluated using data simulated under five different dosing conditions and two different sampling conditions. Comparisons between AUC estimations using these six different algorithms and the theoretical results were made in terms of both overall AUC values and the superimposability of the concentration-time profiles. In well designed studies with ample data points, the algorithm based on IMSL/IDLTM function CSSHAPE with concavity preservation gave the best performance. In contrast, when the frequency of blood collection was limited, the algorithm based on the log trapezoidal rule proved to be stable with reasonable accuracy, and is recommended as the practical method for numerical interpolation and integration in pharmacokinetic studies. Algorithms based on the combination of the log trapezoidal rule and cubic-spline methods using IMSL/IDLTM function CSSHAPE can be developed to enhance overall performance. 相似文献
To elucidate the significance of angiotensin II (AID-induced hypertension chemotherapy, changes of tissue blood flow both in normal subcutis and in tumors (AH109A, LY80) were measured with the hydrogen gas clearance method. A newly-developed anesthetic machine was used to keep the animals' condition constant. Tissue blood flow in normal subcutis and tumors always fluctuated with time under normotension. The nature and the rate of fluctuation in tumor Wood flow were almost identical in two different types of tumors. However, the fluctuation of blood flow in tumor and that in normal subcutis were almost always inversely related when blood flows in these different tissues were measured simultaneously, i.e., when tissue blood flow in normal subcutis decreased, tumor blood flow increased, and vice versa. The findings supported the idea that the connection mode between the tumor vascular bed and normal vascular bed is a parallel circuit. Vascular resistance in the normal vascular bed under All-induced hypertension seemed to be greater than that under normotension, because the All-increased tumor blood flow always exceeded the maximum tumor blood flow under normotension. Due to the fluctuations of tumor blood flow, no-flow or low-flow areas, resistant to delivery of anti-cancer drugs, moved sporadically within the tumor under the normotensive condition. However, good conditions for drug delivery to tumor tissue were induced by All-induced hypertension. 相似文献