Late Effects in Mouse Heart after 60Co γ-irradiation of the Brain: An Ultrastructural Study

Summary

A single dose of 8 or 20 Gy ⁶⁰Co γ-rays was given to C3H male mice at 4 months of age. Degenerative changes in the cardiac muscle due to brain irradiation were observed first at 6 months after irradiation, and became progressively more severe at 12–24 months. The changes seen at the ultrastructural level included myofibrillolysis, the presence of lysosomal-like bodies and interstitial fibrosis. Ultrastructural changes in the control cardiac muscle throughout the experimental period were monitored and only minor aging changes were noted. The coronary arteries of control mice began to show a slight amount of smooth muscle degeneration and fibrosis 1 year into the experiment. At 18 months the lesions became more severe, and at 24 months there was relatively less distinction between the control and the 20 Gy treated group. Degenerative changes in the coronary arteries were noticed at 6 months after irradiation, and became progressively more severe at later times (12–24 months). The major changes included smooth muscle degeneration with fibrosis and the accumulation of debris and extracellular matrix. At 18 months the medial smooth muscle showed severe damage, with accumulations of matrix material and debris. There was additional fibrosis in the adventitial layer. There were few additional changes at 24 months after 20 Gy irradiation. Quantitative analyses indicated that the average fractional volumes of degenerated smooth muscle cells were 13, 27 and 39% in the unirradiated group at 12, 18 and 24 months, respectively, and 13 and 29% in the sham-irradiated group at 12 and 18 months into the experiment, respectively. These percentages were 12, 32 and 49% (P < 0·05) after 8 Gy irradiation, and 19% (P < 0·05), 46% (P < 0·01), and 42% after 20 Gy irradiation, respectively.     

90Sr血管内照射防治内膜损伤后再狭窄

目的研究常规治疗剂量和高剂量99Sr照射对血管壁平滑肌的生物学效应.方法18只新西兰兔分为3组,行髂动脉内膜剥脱术后,12只用90Sr后装技术行血管内照射,距放射源中心轴线2 mm深度血管壁吸收剂量分别为16和50Gy,6只未行血管内照射治疗作为对照组.28 d后处死动物进行组织病理学分析.结果50Gy组血管中层组织为类内皮样细胞所覆盖,其血栓发生率(3/6只)高于对照组(0/6只)和16Gy组(1/6只).16Gy组狭窄指数、增殖指数、增殖细胞核抗原阳性率和凋亡细胞阳性率与对照组比较差异有显著性.50Gy组狭窄指数、增殖指数与对照组和16Gy组比较,差异均有显著性.结论16Gy组血管内膜增生受到明显抑制,剂量增加到50Gy时,内膜增生现象完全受到抑制,除血栓发生率较高外,未见其他如假性动脉瘤等血管严重并发症.     

β射线内照射抑制血管内皮细胞和平滑肌细胞增殖的研究

目的 探讨β射线对血管内皮细胞和平滑肌细胞的细胞效应。方法 培养人脐静脉内皮细胞和牛主动脉平滑肌细胞,接受0、1.25、2.5、5.0、10、20、40 Gy β射线后,以四唑盐(MTT)比色实验评价剂量-效应关系,用划痕实验研究β射线对两种细胞增殖的影响。血管内皮细胞经0、2.5、5.0、10、20 Gy照射后,进行透射电镜超微结构观察和使用流式细胞仪进行DNA倍体及凋亡率分析。结果 血管内皮细胞在照射后2、24 h,在1.25～40 Gy其增殖呈剂量依赖性抑制;在照射后48、72 h,其剂量依赖性抑制在10 Gy时处于平台期。血管平滑肌细胞在照射后2、24和48 h,其增殖抑制在10Gy时处于平台期;在照射后72h,其增殖抑制在5 Gy时处于平台期。在照射后72 h,吸收剂量为5 Gy时,血管平滑肌细胞和内皮细胞的抑制率分别为27.9％和19.0％(P=0.016);吸收剂量为10 Gy时,血管平滑肌细胞和内皮细胞的抑制率分别为33.7％和20.9％(P=0.002)。划痕实验示吸收剂量为5Gy时血管内皮细胞几乎完全充填裂隙,而平滑肌细胞较少充填裂隙;10 Gy照射后,内皮细胞充填裂隙数量减少,而平滑肌细胞几乎未充填裂隙。透射电镜未发现典型的凋亡征象,流式细胞仪检查各实验组和对照组的凋亡率均<4.4％。DNA倍体分析发现对照组G_2/M期细胞数百分比为13.09％,各照射组依次为16.     

高剂量照射兔骨骼肌放射损伤的超微病理研究

目的 建立新西兰兔骨骼肌高剂量照射放射损伤模型,研究病理改变.方法 采用随机数字表法将28只新西兰兔分为照射组和对照组.照射组给予9 MeV电子线一次性照射单侧臀部80 Gy,分别于照射后1个月及6个月时取照射区骨骼肌组织,应用光镜和透射电镜观察其病理变化.结果 照射后1个月:光镜下肌细胞变性及坏死,肌间出血明显;电镜下肌细胞内见变性的肌原原纤维肿胀,明暗带结构不清,坏死区呈电子密度深浅不一的无定形区,线粒体肿胀、空泡变性.照射后6个月:光镜下肌细胞变性及坏死较1个月时明显,坏死区可见核碎裂,部分肌间血管管壁增厚、管腔闭塞,神经纤维退行性变,肌间纤维组织增生;电镜下变性区肌丝大量丢失,肌节萎缩,无定形坏死区范围增大,核内染色质减少、边集,胶原原纤维增生明显,线粒体异常增生.结论 9 MeV电子线一次性照射80 Gy照射兔骨骼肌后,骨骼肌细胞线粒体损伤、肌间血管及神经损伤可能是促进肌细胞及变性坏死的重要因素.     

Structural and functional alterations in the rat lung following whole thoracic irradiation with moderate doses: injury and recovery

PURPOSE: To characterize structural and functional injuries following a single dose of whole-thorax irradiation that might be survivable after a nuclear attack/accident. METHODS: Rats were exposed to 5 or 10 Gy of X-rays to the whole thorax with other organs shielded. Non-invasive measurements of breathing rate and arterial oxygen saturation, and invasive evaluations of bronchoalveolar lavage fluid, (for total protein, Clara cell secretory protein), vascular reactivity and histology were conducted for at least 6 time points up to 52 weeks after irradiation. RESULTS: Irradiation with 10 Gy resulted in increased breathing rate, a reduction in oxygen saturation, an increase in bronchoalveolar lavage fluid protein and attenuation of vascular reactivity between 4-12 weeks after irradiation. These changes were not observed with the lower dose of 5 Gy. Histological examination revealed perivascular edema at 4-8 weeks after exposure to both doses, and mild fibrosis beyond 20 weeks after 10 Gy. CONCLUSIONS: Single-dose exposure of rat thorax to 10 but not 5 Gy X-irradiation resulted in a decrease in oxygen uptake and vasoreactivity and an increase in respiratory rate, which paralleled early pulmonary vascular pathology. Vascular edema resolved and was replaced by mild fibrosis beyond 20 weeks after exposure, while lung function recovered.     

18F-FLT体外监测结肠癌细胞早期放射反应

目的 评价18F-脱氧胸腺嘧啶核苷（FLT）监测结肠癌细胞早期放射反应的作用.方法 应用四甲基偶氮唑蓝（MTT）检测并绘制SW480细胞受X线照射后生长曲线,光学显微镜下观察细胞形态变化.流式细胞仪检测照射后肿瘤细胞增殖周期的重新分布.分别于体外细胞以及肿瘤内检测照射前、后细胞摄取18F-FLT的变化.将18F-FLT（0.05±0.01）MBq加入培养液孵育细胞,分别于30,60,90,120 min测定细胞摄取18F-FLT的放射性.经荷瘤裸鼠尾静脉注射18F-FLT（1.90±0.85）MBq（0.25 ml）,60 min后处死动物,切除肿瘤与肌肉、肺、肝等,测定肿瘤与其他脏器摄取放射性比值变化.应用单因素方差分析进行统计学处理.结果 X线照射后,SW480细胞增殖受到明显的抑制,呈剂量依赖性.细胞形态随照射剂量的不同发生不同的变化.照射后细胞周期发生重新分布.10 Gy组,S期细胞百分比24 h从33.23%降至15.19%,72 h后降至12.44%.20 Gy组,S期细胞百分比24 h后从33.23%降至9.24%,72 h后降至5.43%.体外摄取实验发现,注射后60 min,SW480细胞摄取18F-FLT百分比为（5.21±1.60）%,10 Gy照射24 h后下降至（4.27±0.48）%,72 h降至（3.39±0.59）%.20 Gy组：照射后24 h,SW480摄取的放射性百分比下降至（3.41±0.58）%,72 h后降至（1.63±0.49）%.两照射组在72 h内分别下降了34.94%,69.72%（24 h∶F=8.253,P=0.009;72 h∶F=36.715,P＜0.001）.单位质量肿瘤组织摄取的18F-FLT随照射剂量的增加而逐渐降低（10Gy组：F=12.388,P=0.007;20 Gy组：F=16.744,P=0.004）.结论 18F-FLT在结肠癌细胞内的摄取可以快速反映照射治疗后的细胞变化,18F-FLT可能用于检测结肠癌放射治疗早期反应.     

Delayed vascular injury after single high-dose irradiation in the rat brain: histologic immunohistochemical, and angiographic studies.

PURPOSE: To investigate structural and functional changes in rats after focal brain irradiation by using histologic, immunohistochemical, and angiographic methods. MATERIALS AND METHODS: Sixty rats were irradiated stereotactically with photons from a 15-MeV linear accelerator. Two collimators and single doses ranging from 20 to 100 Gy were used to treat stereotactically defined areas of 3.7- and 4.7-mm cross section (80% isodose) in the right frontal lobe. The dose-response relationship for the end-point necrosis at 19 months revealed a mean tolerance dose (D50) of 34.2 Gy (standard errors: +4.1, -3.7 Gy). Histologic, immunohistochemical, and angiographic examinations were performed to evaluate delayed radiation effects. RESULTS: All animals irradiated with 100 Gy developed radiation necrosis after 9 months. Microangiography and immunohistochemical fluorescence staining of the endothelial cells revealed dose-dependent vascular dilatation and rarefaction. Animals irradiated with 20-50 Gy showed no morphologic changes after 9 months. With irradiation of 30-50 Gy, histologic vascular changes that increased with dose were found after 19 months. At that time, no changes were detected after irradiation with 20 Gy with both field sizes and after irradiation with 30 Gy and the 2-mm collimator. Radiation-induced functional disturbances of the brain vasculature could be demonstrated by extravasation of contrast medium by using a microangiographic technique. CONCLUSION: The observed effect had a definite dependence on dose, volume, and time after treatment.     

The effect of Captopril on benign and malignant reactions in irradiated rat skin

The effect of the angiotensin converting enzyme inhibitor Captopril on the severity of radiation-induced epilation and moist desquamation and the incidence of skin tumours was determined for up to 52 weeks in male rats. The irradiation consisted of a range of single doses (0, 10, 20, 30 Gy) of 60Co gamma rays to a 3.5 cm2 right hemithorax port. Half of each radiation dose group consumed control powdered chow, and half consumed chow containing Captopril (50 mg/kg/day) continuously after irradiation. There were time- and radiation-dose-dependent increases in all three skin reactions. Rats exposed to 10 Gy exhibited a mild and transient epilation, but no moist desquamation or neoplasia in the radiation port. In animals exposed to 30 Gy, however, epilation began at 2 weeks after irradiation, reached a peak at approximately 7 weeks, then persisted essentially unchanged through 52 weeks. Captopril had no significant effect on the epilation reaction. Two waves of moist desquamation were observed after 30 Gy. The first appeared at 3 weeks after irradiation, reached a peak from 6-10 weeks, then subsided partially but significantly from 12-26 weeks. The second wave of moist desquamation began at 26-28 weeks, often was ulcerative, and occasionally was accompanied by the appearance of tumours in the irradiated volume. Captopril significantly (p less than 0.05) reduced the severity of both phases of the moist desquamation reaction after 30 Gy, and reduced the percentage of animals exhibiting the most severe desquamation score (involving 50% of the radiation port). Of particular interest was the observation that Captopril also reduced the incidence of tumours. Of the 14 tumours detected, all were malignant (fibrosarcomas, squamous cell carcinomas), and only three (p less than 0.05) occurred in rats receiving Captopril. Multiple tumours (three cases), tumours induced by 20 Gy (three cases), and tumours appearing before 6 months (one case) were observed only in rats consuming control diet, never in Captopril-treated animals. Animals which developed tumours in the second 6 months post-irradiation exhibited significantly more severe moist desquamation during the first 6 months than did the tumour-free members of their treatment group. Thus Captopril, known to ameliorate acute lung damage in irradiated rats, also reduces chronic benign and malignant skin reactions in the radiation treatment field.     

Increased Deposition of von Willebrand Factor in the Rat Heart after Local Ionizing Irradiation

BACKGROUND AND PURPOSE: Von Willebrand factor (vWf), a glycoprotein involved in blood coagulation, is synthesized by endothelial cells. Increased amounts of vWf in blood plasma or tissue samples are indicative of damaged endothelium. In the present study, mRNA expression and localization of vWf were determined in irradiated rat heart tissue. MATERIAL AND METHODS: Sprague-Dawley rats received local heart irradiation with a single dose of 0, 15, or 20 Gy. Hearts were dissected at different time points (up to 16 months) after irradiation. In a second experiment, rats were injected with the radioprotector amifostine (160 mg/kg, i. p.) 15-20 min before irradiation and sacrificed after 6 months. Immunohistochemistry was performed using a polyclonal anti-vWf antibody. Serial sections were subjected to a general rat endothelial cell immunostaining (RECA-1) or a collagen staining (picrosirius red). mRNA expression was determined by using PCR. RESULTS: In control tissue, all endothelial cells lining the lumen of the endocardium and coronary arteries, but not capillary endothelial cells, were stained for vWf. 1 month after irradiation with both 15 and 20 Gy, myocardial capillaries became immunoreactive. From 3 months onward, staining was observed also within the extracellular matrix (ECM) of fibrotic areas. At mRNA level, no changes in vWf could be observed at all time points after irradiation, suggesting that vWf deposition was not due to increased biosynthesis of the protein. In sections of amifostine-treated rat hearts, vWf staining was increased to a lesser extent. CONCLUSION: These dose- and time-dependent increases in deposition of vWf indicate the presence of damaged endothelium in the irradiated rat heart. These increases in vWf accumulation precede development of fibrosis in the subendocardial layer and myocardium of the left ventricles, right ventricles, and atria.     

RBE values for colo-rectal injury after caesium 137 gamma-ray and neutron irradiation. I. Single doses

Colo-rectal damage in mice has been assessed after caesium gamma irradiation and 3 MeV neutrons given as single doses. Several assays were used, including body weight changes, faecal deformity and lethality. Dose response curves have been constructed for each assay at different times after irradiation, ranging from 10 days to 16 months. The data have been analysed in terms of the time course of expression of damage and the RBE for neutrons. An initial loss of weight at 10-20 days was presumably related to epithelial denudation, but a dose-dependent weight reduction (compared with controls) persisted over the animal's life span. Mice died progressively after localised pelvic gamma irradiation; there was no sharp demarcation between an early and late phase of lethal injury. Death resulted from intestinal stricture or stenosis. The time course for lethality was qualitatively different after neutrons, with little progression of damage between 5 and 11 months. Faecal deformity was detectable as a higher proportion of small pellets when the rectum became constricted by fibrosis. No significant faecal deformity was observed before 6 months after which time dose response curves could be obtained. The RBE for early damage (assessed at 1-3 months) was 2.2-2.7. This fell to 1.7-1.9 for late damage (determined at 10-15 months) over the range of neutron doses of 7.5-12 Gy. The need for sublethal assays allowing for sequential evaluation of radiation damage within the same animal is stressed, as is the need to compare RBE values from early and late endpoints at equivalent neutron doses.     

Serial histopathological changes in irradiated guinea pig lung receiving conventional fractionated and hyperfractionated irradiation.

PURPOSE: To determine serial histopathological differences in guinea pig lungs receiving the same total dose as clinically used between conventional fractionated and hyperfractionated irradiation. METHODS AND MATERIALS: The guinea pigs received 80 Gy in 40 daily fractions of 2 Gy each (conventional fractionation), 80 Gy in 80 fractions of 1 Gy each twice a day (hyperfractionation), 81 Gy in 27 daily fractions of 3 Gy each (conventional fractionation), or 81 Gy in 54 fractions of 1.5 Gy each twice a day (hyperfractionation). We evaluated the histopathological changes of irradiated guinea pig lungs at 1, 2, 3, 6, 9, and 12 months after irradiation. RESULTS: The guinea pig lungs that received 81 Gy in 27 daily fractions showed histopathological changes of inflammation including formation of lymph follicles after 6 months. The lungs which received 81 Gy in 54 fractions showed similar but slightly less pronounced changes than those that received 81 Gy in 27 daily fractions. The guinea pig lungs of other groups showed no histopathological changes during the observation period. CONCLUSION: In hyperfractionated irradiation the damage to the guinea pig lung is quantitatively less than that occurring as a result of conventional fractionated irradiation of the same total dose.     

De novo femoropopliteal stenoses: endovascular gamma irradiation following angioplasty--angiographic and clinical follow-up in a prospective randomized controlled trial

PURPOSE: To assess and report the follow-up results of a randomized controlled trial on centered endovascular gamma irradiation performed after percutaneous transluminal angioplasty (PTA) for de novo femoropopliteal stenoses. MATERIALS AND METHODS: Thirty patients who underwent PTA for de novo femoropopliteal stenoses were randomly assigned to undergo 14-Gy centered endovascular irradiation (irradiation group, n = 15) or no irradiation (control group, n = 15). Intraarterial angiography was performed 6, 12, and 24 months after treatment; duplex ultrasonography (US), the day before and after PTA and 1, 3, 6, 9, 12, 18, and 24 months later. Treadmill tests and interviews were performed the day before PTA and 1, 3, 6, 9, 12, 18, and 24 months later. Results of angiography, duplex US, treadmill tests, and interviews were evaluated with the nonpaired t or the Fisher exact test. RESULTS: Baseline characteristics did not differ significantly between the two groups. Mean absolute individual changes in degree of stenosis, compared with the degrees of stenosis shortly after PTA, in the irradiation group versus in the control group were -10.6% +/- 22.3 versus 39.6% +/- 24.6 (P <.001) at 6 months, -2.0% +/- 34.2 versus 40.6% +/- 32.6 (P =.002) at 12 months, and 7.4% +/- 43.2 versus 37.7% +/- 34.5 (P =.043) at 24 months. The rates of target lesion restenosis at 6 (P =.006) and 12 (P =.042) months were significantly lower in the irradiation group. The numbers of target lesion re-treatments were similar between the groups, but target vessel re-treatments were more frequent in the irradiation group. There were no significant differences in interview or treadmill test results between the two groups at t test analysis. CONCLUSION: The degree of stenosis was significantly reduced 6, 12, and 24 months after angioplasty of de novo femoropopliteal stenoses in the patients who underwent endovascular irradiation.     

32P液体球囊血管内照射预防血管成形术后再狭窄

目的 探讨^32P液体球囊血管内近距离照射治疗对防止血管成形术后再狭窄的量效关系及其抑制再狭窄发生的可能机制。方法 27只雌性大白兔据动脉球囊扩张损伤后，实验组(18只)分别给予3、9、18和36Gy^32P液体球囊行内照射治疗，对照组(9只)灌注生理盐水。术后于不同时间点取材，行HE染色、增殖细胞核抗原(PCNA)免疫组织化学染色以及电镜观察血管组织形态学的改变，用计算机图像分析法测量管腔面积和内膜面积。结果 对照组血管内膜明显增生，管腔变狭窄。18Gy组血管壁平滑肌细胞增殖明显受抑，细胞凋亡增加，管腔面积无明显丢失；36GY组血栓形成明显；3和9Gy组均未观察到明显的生物效应。结论 ^32P液体球囊血管内照射可防止血管成形术后再狭窄发生，其机制可能为抑制血管壁平滑肌细胞增殖，促进其凋亡及改善血管重塑形。     

Late radiation fibrosis in rat lung following protons and 250 kV X-rays irradiation

To investigate the biological effectiveness of proton beams in the development of pulmonary fibrosis the lungs of male 7-week-old Wistar rats were locally irradiated with a single dose of 10-50 Gy of 250 kV X-rays and modulated, 250 MeV protons at Particle Radiation Medical Science Center (PARMS). Animals were sacrificed serially after 3, 6, 9 and 12 months at which times the development of the fibrotic lesion in alveolar walls and peribronchial connective tissues was assessed quantitatively by analysis of microscopic images of Azan-Mallory stained sections. Fibrosis index (FI) values in alveolar walls and peribronchial tissues were defined as the fraction (in percent) of a specific image area, the gray level of which represents collagen deposits. Using this FI values, the increase of fibrotic lesion following 0-40 Gy of X-rays irradiation as a function of time were observed better in alveolar walls than in peribronchial tissues. Compared with 250 kV X-rays, 30 Gy of proton beams irradiation produced less increase in the time course of FI values of alveolar walls and dose-response curve at 12 months later suggested that the fibrotic lesion in alveolar walls after protons exposure of the doses above 30 Gy might develop more slowly.     

β射线局部照射预防自体移植静脉内膜增生的实验研究

目的：研究放射性同位素局部照射对自体移植静脉段内膜增生反应的影响及其可能机理。方法：建立40只大鼠自体静脉移植模型，随机分成对照组（单纯自体静脉移植组），8，18，36Gy组（按不同32P内膜照射剂量），每组10只，2周后取材固定，行HE染色，Verhoeff弹力纤维染色，增殖细胞核抗原（PCNA）免疫组化测定（SP法），计算机图像分析仪测量移植血管内膜厚度。结果：移植静脉段的内膜平均厚度：对照组与8Gy组差异无显著性（P＞0．05），但高于18，36，Gy组（P＜0．05），18Gy组与36Gy组间差异无显著性（P＞0．05），PCNA阳性片示，18，36Gy组VSMC增殖较对照组受到明显抑制（P＜0．01），两组差异无显著性（P＞0．05），8Gy组较对照组差异无显著性（P＞0．05），结论：适当剂量β射线局部照射可以抑制自体移植静脉的内膜增生及平滑肌细胞（SMC）的增殖，减少再狭窄的发生。     

Structural and functional alterations in the rat lung following whole thoracic irradiation with moderate doses: Injury and recovery

Purpose:?To characterize structural and functional injuries following a single dose of whole-thorax irradiation that might be survivable after a nuclear attack/accident.

Methods:?Rats were exposed to 5 or 10 Gy of X-rays to the whole thorax with other organs shielded. Non-invasive measurements of breathing rate and arterial oxygen saturation, and invasive evaluations of bronchoalveolar lavage fluid, (for total protein, Clara cell secretory protein), vascular reactivity and histology were conducted for at least 6 time points up to 52 weeks after irradiation.

Results:?Irradiation with 10 Gy resulted in increased breathing rate, a reduction in oxygen saturation, an increase in bronchoalveolar lavage fluid protein and attenuation of vascular reactivity between 4–12 weeks after irradiation. These changes were not observed with the lower dose of 5 Gy. Histological examination revealed perivascular edema at 4–8 weeks after exposure to both doses, and mild fibrosis beyond 20 weeks after 10 Gy.

Conclusions:?Single-dose exposure of rat thorax to 10 but not 5 Gy X-irradiation resulted in a decrease in oxygen uptake and vasoreactivity and an increase in respiratory rate, which paralleled early pulmonary vascular pathology. Vascular edema resolved and was replaced by mild fibrosis beyond 20 weeks after exposure, while lung function recovered.