Recovery from UV-induced Potentially Lethal Damage in Systemic Lupus Erythematosus Skin Fibroblasts

Summary

The repair of ultraviolet light-induced potentially lethal damage was investigated in density-inhibited skin fibroblast cell strains derived from patients with systemic lupus erythematosus. The effect of exposure to polychromatic ultraviolet light composed of environmentally relevant wavelengths or to the more commonly studied, short wavelength (254 nm) ultraviolet light was studied. Systemic lupus erythematosus cells, which are hypersensitive to ultraviolet light under growth promoting conditions, were able to repair potentially lethal damage as well as normal cells.     

The Influence of Experimental Design and Data Analysis on the Determination of Recovery Kinetics of Radiation Damage between Acute Dose-rate Treatments in Vivo

Summary

Current interest in determining the rate of recovery of damage between radiation doses in fractionated treatments has resulted in the development of several experimental designs and methods of analysis to address this. One approach is where two or more fractions are given with a varying interval. Isoeffect doses are then determined from the dose—response curves for each interval, and these are plotted on a logarithmic axis against time on a linear scale. An estimate of the rate of dose recovery can then be made if the data show monoexponential or well-defined multiexponential kinetics. However, three problems can be identified in this simple protocol. First, most repair models (e.g. Thames' IR and Curtis' LPL) assume that between two doses log_e(cell survival), i.e. underlying effect, not dose itself, recovers exponentially with time. Experimental data support this assumption. Since underlying effect and dose are not linearly related, recovery measured from the change in isoeffect dose can appear substantially slower (depending on dose per fraction) than the true underlying recovery rate of damage. This artifact is avoided by converting dose increments into changes in underlying effect (with the linear-quadratic model) or by measuring underlying effect more directly in ‘top-up’ experiments. The use of (neutron) top-up experiments is preferred, as it enables recovery between constant X-ray doses per fraction to be studied, and makes no prior assumptions regarding either the shape of the X-ray dose—response curve or how recovery takes place, although the shape of the neutron dose—response curve must be known. Second, plotting log(unrecovered damage) against time can overestimate recovery half-times, because such plots cannot handle negative values and therefore become naturally weighted in favour of the data from the longer time intervals where the difference from complete recovery is smallest. This problem is managed by using nonlinear regression to fit the values of unrecovered damage expressed on a linear scale against interval. Third, experiments using three or more evenly spaced fractions, ‘concertina’-style, permit interaction between non-adjacent fractions. If this is not taken account of, then recovery appears to be initially faster and multiexponential, even though the underlying recovery may be actually monoexponential. Thus concertina experiments are poor at resolving the precise shape of recovery-kinetics profiles and are less suited for measuring any dependence of recovery rate on dose per fraction compared with approaches using either just two fractions, or two fractions per day.     

不同剂量率X射线辐照对小鼠免疫系统的影响

目的 检测经相同剂量不同剂量率X射线照射的BalB／C小鼠外周血淋巴细胞周期及胸腺和脾脏指数。方法 18只BalB／c小鼠随机分为对照组（controI），低剂量率照射组（20cGy／min）和高剂量率照射组（300cGy／min），每组6只。低剂量组和高剂量组采用剂量率分别为2．0cGy／min和300cGy／min的1GyX射线对小鼠进行全身照射，24h后取血及器官，用流式细胞仪检测外周血淋巴细胞的周期变化，用称量的方法得到胸腺和脾脏指数。结果 高剂量率辐射时，小鼠外周血淋巴细胞的损伤较低剂量时大，而且对雄性鼠的影响大于雌性；同时，胸腺和脾脏指数变化也随着剂量率的增大而减小。结论 低剂量率的照射对小鼠外周血淋巴细胞、胸腺和脾脏的影响较高剂量率辐射小；雌性鼠的辐射耐受能力较雄性强。     

The Kinetics of Repair in Mouse Lung after Fractionated Irradiation

Summary

The kinetics of repair of sublethal damage in mouse lung was studied after fractionated doses of ¹³⁷Cs γ-rays. A wide range of doses per fraction (1·7–12 Gy) was given with interfraction intervals ranging from 0·5 to 24 h. The data were analysed by a direct method of analysis using the incomplete repair model. The half-time of repair (T_1/2) was 0·76 h for the pneumonitis phase of damage (up to 8 months) and 0·65 h for the later phase of damage up to 12 months. The rate of repair was dependent on fraction size for both phases of lung damage and was faster after large dose fractions than after small fractions. The T_1/2 was 0·6 h (95 per cent c.1. 0·53, 0·69) for doses per fraction greater than 5 Gy and 0·83 h (95 per cent c.1. 0·76, 0·92) for doses per fraction of 2 Gy. Repair was nearly complete by 6 h, at least for the pneumonitis phase of damage. To the extent that extrapolation of these data to humans may be valid, these results imply that treatments with multiple fractions per day that involve the lung will not be limited by the necessity for interfraction intervals much longer than 6 h.     

CT扫描机X线球管是否损坏的判断

Ｘ线球管 (Ｘ -ｒａｙｔｕｂｅ)是ＣＴ机中是一个极为贵重的部件 ,但它的使用寿命是有限的 ,一般厂家保证曝光次数为 5万次左右 ,而实际的使用寿命有的曝光次数可高达几十万次 ,而质量较差的只能使用 67万次 ,所以对Ｘ线球管损坏的判断不能只从曝光次数来衡量 ,也不能被一些假象所掩盖。因此 ,在多种多样的故障现象中作出正确的判断 ,将使你赢得宝贵的时间和为医院免去不必要的经济损失。在实际工作中 ,Ｘ线球管达到使用寿命而损坏的原因是多种多样的 ,一般有以下几个方面。1、Ｘ线球管发射Ｘ线的能力大大降低 (致使图像质量不能满足要求 )…     

ICU患者皮肤受损的护理体会

目的:探讨ICU患者压疮及皮肤受损的护理措施及体会.方法:对本组患者创面采用预防及加强护理与美宝创疡贴换药治疗法相结合进行综合治疗.结果:Ⅱ度创面平均5天～7天愈合,Ⅲ度创面平均7天～10天愈合,Ⅳ度创面平均12天～30天愈合.结论:通过加强预防措施及基础护理,结合美宝创疡贴换药治疗,可有效防控创面感染,减少创面的再次损伤和疼痛,是创面愈合的重要保障.     

The Action of Ultra-violet Light on Repair of X-ray Damage in L-cells Grown in Culture

Summary

L-cells are capable of considerable recovery after x-irradiation. The processes responsible for recovery start promptly after irradiation. Cells irradiated with ultra-violet light do not display any recovery. The application of ultra-violet light to x-irradiated cells led to partial inhibition of recovery after x-rays.     

X线衰减校正对SPECT断层图像质量的影响

目的:评价X线衰减校正对SPECT断层图像质量的影响.材料和方法:Jaszczak模型行常规断层显像,肺癌患者1例行99mTc-octreotide SPECT显像,对衰减校正图像(AC)和非衰减校正图像(NAC)进行对比分析.结果:AC图像较NAC图像计数明显增加,尤以中心部分显著,图像更加趋于均匀;分辨率方面,NAC图像分辨率为9.5mm,AC图像分辨率为7.9mm,对比度方面两者无显著性差异(P>0.05).结论:X线衰减校正可改善图像质量.     

17种生物碱类药物体外经皮渗透行为的实验研究

目的　研究生物碱类药物经皮吸收系数与药物油 /水分配系数的关系。方法　采用Ficks扩散装置测定 17种生物碱类药物在小鼠皮的透皮速率 ,并与含 2 %促渗剂氮酮比较。结果　生物碱类药物的经皮渗透系数 (kp )与药物油 /水分配系数(logk )的关系式为 :logkp =7.35× 10 -2 - 3.0 79× 10 -2 logk - 8.11(logk) 2 ;logkp( 2 %Azo) =8.32× 10 -2 - 2 .6 8× 10 -2 logk - 5 .2 7(logk ) 2 ;结论　 17种药物的油 /水分配系数平均最佳值为 2 .83,含 2 %氮酮后的其平均最佳值为 3.17。     

低曝光剂量对CT检出肺结节的影响

目的　探讨低剂量扫描对CT检出肺结节的影响。方法　选择肺转移瘤 2 6例 ,分别应用 195mAs / 6.5mm(剂量 /层厚 ) ,195mAs/ 3 .2mm ,5 0mAs/ 3 .2mm ,3 0mAs/ 3 .2mm 4种方案扫描肺部 ,统计在不同曝光剂量条件下检出的肺结节的数量、大小、部位。结果　 195mAs/ 3 .2mm ,5 0mAs/ 3 .2mm ,3 0mAs/ 3 .2mm组之间的肺结节检出数在总体上无显著差异 ,但按肺结节大小分类分析时 ,随曝光剂量的降低 ,对 <2mm和 5mm的肺结节的检出数有所减少 ,并且低剂量下 ,图像噪声明显增加。虽然 3 0mAs/ 3 .2mm组的图像噪声比 195mAs/ 6.5mm的明显高 ,但对肺结节的检出数明显高于 195mAs/ 6.5mm组。结论　总的来说 ,减低曝光剂量 ,图像噪声增加 ,图像质量下降 ,伪影可以掩盖细小肺结节 ,但在一定范围内适当降低曝光剂量 ,对肺结节的检出数无显著影响。低剂量薄层厚扫描筛查肺结节优于常规剂量常规层厚扫描。     

Recovery kinetics of X-ray damage in mouse skin: the influence of dose per fraction.

The rate of recovery from radiation damage, as a function of dose per fraction, was investigated in mouse skin. Two different experimental designs were used, both incorporating the neutron top-up technique which enables the X-ray dose per fraction to be kept constant whilst changing the interfraction interval. Either equally spaced X-ray fractions (concertina design) or single or multiple pairs of X-ray doses (single and multiple split-dose designs) were given at varying intervals, followed by graded doses of neutrons. A wide range of X-ray doses per fraction were investigated (from 1 to 10.5 Gy) and the data were analysed using the Thames Incomplete Repair (IR) model modified for use with neutron top-up doses. Analyses of the data, obtained from five different experiments, indicate that the rate of recovery from radiation damage is significantly faster at doses per fraction between 1 and 4.4 Gy than at 10.5 Gy. These data appear not to support the assumption, made by most recovery models, that the rate of recovery is independent of dose.     

多层螺旋CT准直对图像质量和辐射剂量的影响

目的 探讨多层螺旋CT不同准直宽度对图像质量和辐射剂量的影响与关系.方法 使用Philips Brilliance 16螺旋CT机及随机水模(头模直径20cm,体模直径30cm),分别使用头模准直16×0.75(总准直宽度12 mm)和16×1.5(总准直宽 度24 mm)轴扫;体模准直4×0.75(总准直宽度3 mm)、4×1.5(总准直宽度6 mm)、16×0.75(总准直宽度12 mm)、16×1.5(总准直宽度24 mm)、4×3(总准直宽度12 mm)及8×3(总准直宽度24 mm)螺旋扫描,取各种准直规格扫描图像各8幅,设中心及相当于3、6、9、12点位置距水模边缘下方2 cm处为感兴趣区,测量、记录各感兴趣区的CT值标准差(SD)及各种准直规格扫描的容积CT剂量指数(CTDIvol)值,所得数据进行统计学处理.结果 头颅轴 扫模式的2种准直规格CTDIvol分别为91.3 mGy和83.0 mGy,图像噪声分别为2.948±0.283和2.833±0.721.体模螺旋扫描,准直4×0.75与4×1.5 2种准直规格,其CTDIvol分别为25.4 mGy和18.3 mGy,图像噪声分别为14.874±3.571和14.594±3.265;16×0.75、16×1.5 2种准直规格,其CTDIvol分别为15.5 mGy和14.1 mGy,图像噪声分别为16.918±3.235和15.776±3.130;4×3、8×3 2种准直规格,其CTDIvol分别为15.5 mGy和14.1 mGy,图像噪声分别为17.276±3.564和16.722±3.366.各组准直规格扫描图像噪声无显著性差异(P>0.05).结论 准直宽度与辐射剂量成反比关系,对图像质量无显著影响,建议尽可能采用较大准直宽度扫描以降低辐射剂量.     

Progressive Development of Radiation Damage in Mouse Kidneys and the Consequences for Reirradiation Tolerance

Summary

The aim of this study was to investigate the influence of protracted overall treatment times on the development and repair of renal irradiation injury in mice.

Functional kidney damage was measured, from the proportion of ⁵¹CrEDTA remaining in the plasma at 30 min after injection of the tracer. Damage was assessed at monthly intervals for up to 14 months after two equal doses of X-rays given in 1 day, 1 month or 6 months. There was no difference between the time of onset or rate of development of damage after two fractions in 1 day or 1 month, but there was a time lag of 7–15 weeks (depending on dose) before the development of damage after 2F given in 6 months. After this time lag the rate of progression of damage was the same for 2F/6 months as for 2F in the shorter intervals. There was therefore no indication of any increase in total tolerated dose for the kidney when the treatment time was protracted, although the time scales for onset of this damage differed.

Tolerance of mouse kidneys to reirradiation at 6 months after single doses of 6–12 Gy was also assessed. All of the previously irradiated animals developed a more severe renal impairment after reirradiation than did the age-matched control mice. The most severe damage occurred in mice which received the highest initial radiation doses, but doses of only 6 Gy were sufficient to markedly reduce the tolerance to reirradiation.

It was concluded from these studies that no additional dose-sparing (tissue recovery) took place in the kidneys during a 6-month interval. This was true even when the initial radiation dose alone was insufficient to cause measurable renal dysfunction.     

Dose reduction technique in diagnostic X-ray computed tomography by use of 6-channel multileaf collimators

Recently, region-setting computed tomography (CT) has been studied as a region of interest imaging method. This technique can strongly reduce the radiation dose by limiting the irradiation field. Although mathematical studies have been performed for reduction of the truncation artifact, no experimental studies have been performed so far. In this study, we developed a three-dimensional region-setting CT system and evaluated its imaging properties. As an experimental system, we developed an X-ray CT system with multileaf collimators. In this system, truncated projection data can be captured by limiting of the radiation field. In addition, a truncated projection data correction was performed. Finally, image reconstruction was performed by use of the Feldkamp–Davis–Kress algorithm. In the experiments, the line profiles and the image quality of the reconstructed images were evaluated. The results suggested that the image quality of the proposed method is comparable to that of the original method. Furthermore, we confirmed that the radiation dose was reduced when this system was used. These results indicate that a 3D region-setting CT system using 6-channel multileaf collimators can reduce the radiation dose without in causing a degradation of image quality.     

皮肤扩张术在面颈部皮肤缺损的应用

目的：探讨面颈部烧伤或创伤后瘢痕、斑痣、血管瘤、白癜风等皮肤病变切除后修复皮肤缺损的理想措施。方法：本组对56例面颈部瘢痕及皮肤损伤所致的皮肤缺损患者，采用皮肤软组织扩张的方法，根据病变位置、缺损面积及形态，选用不同类型、不同容量，以最佳的设计方案埋植一个或数个扩张器，使二期手术具备质量高，皮肤面积充足的皮瓣修复缺损，尽量减少辅助切口及瘢痕。结果：面颈部器官形态、功能均获得满意效果，提高了面颈部缺损的修复质量。结论：皮肤软组织扩张术修复面颈部皮肤缺损，具有颜色质地好，表情自然，切口小，瘢痕少，术区皮肤不皱缩的优点。