Radiation-induced hydronephrosis in the rat: a new experimental model

An experimental model for investigating the effects of localized X-irradiation of a single ureter or the bladder trigone in rats is described. Obstruction of the urinary tract in the irradiated region gives rise to hydroureter and hydronephrosis and the development of these, as detected urographically, gives a clear-cut end point. After irradiation of the ureter with a single dose of 37.4 Gy many rats died of gut lesions but after 23.4 Gy only one such death occurred while 14 of 16 rats developed hydronephrosis. Irradiation of the bladder trigone was not associated with intercurrent deaths, even after 40 Gy, and after 25 Gy 9 of 11 rats developed hydronephrosis.     

不同剂量x射线对大鼠精子CRISP2mRNA表达水平的影响

目的：观察不同剂量x射线对大鼠精子CRISP2mRNA表达水平的影响,探讨其在电离辐射所致大鼠精子功能改变中的作用。方法：用吸收剂量为1、2、4、和6Gy的x射线分别照射活体SD大鼠的外生殖系统1…4812、24h后,用PCR技术检测精子CRISP2基因mRNA表达水平;用光学显微镜观察精予活力。以未照射组为对照。结果：4、6GyX射线照射不同时间（1、4、8、12、24h时）后大鼠精子的CRISP2mRNA相对表达量均较对照组显著下降（P．〈0．05）,其中6Gb,照射24小时后相对表达量最低（P〈0．01）,而4Gy照射组与6Gy照射组相比较差异无统计学意义（P〉0．05）;2Gyx射线照射8h后CRISP2mRNA相对表达量下降有统计学意义（P〈0．05）;2GyX射线照射1、4h后及1GyX射线照射不同时间（1、4、8、12、24la）后大鼠精子的CRISP2mRNA相对表达量较对照组下降,但差异无统计学意义（P〉O．05）。1、2GyX射线照射不同时间（1、4、8、12、24小时）及4GyX射线照射（1、4、8h）后,精子活力与正常对照组相比无明显改变（P〉0．05）;4GyX射线照射12、24h后大鼠精子活力显著低于正常对照;6GyX射线照射不同时间（1、4、8、12、24h）后,精子活力明显低于对照组（P〈0．05）。结论：不同剂量X射线照射不同时间可导致SD大鼠精子活力下降,这可能与其下调CRISP2基因的mRNA表达水平有关。     

Quantitative regularities and peculiarities of the development of the cerebral form of radiation sickness at fractionated irradiation

Several peculiarities in manifestations of cerebral form of radiation sickness have been revealed at a fractionated double irradiation with equal and unequal doses per fraction and different intervals between the fractions. A reliable increase in average lifespan of rats irradiated with (100 + 100 Gy) equal doses at 10 and 60 min intervals between two fractions compared to the single radiation exposure to 200 Gy has been obtained. Lifespan of rats irradiated with a total dose greater than 200 Gy in most cases of double exposures with 10 min interval was reliably less than that for animals after a single exposure. The influence of the first dose on the reduction of animal average lifespan increased with fraction dose increasing from 150 to 300 Gy and was most pronounced at the total exposure dose of 400 Gy. Reaction of rats on the repeated irradiation was significantly weakened in comparison with the reaction on the first exposure. At a study of capacitation the interval of 30 min appeared to be more favorable compared to 10 min interval. Importance of a dose value in the first fraction has been demonstrated: the higher this value the worse the capacity of the rats 3 hours after the repeated exposure.     

Late occurring lesions in the skin of rats after repeated doses of X-rays

Late radiation damage, characterized by atrophy and necrosis in the skin and subcutaneous tissues, has been demonstrated in both the tail and feet of rats. The incidence of necrosis increased with total dose. These total doses, in the range 72-144 Gy, were given as 4-8 treatments of 18 Gy, each dose separated from the next by an interval of 28 days. This treatment protocol minimized acute epithelial skin reactions. The same regime applied to the skin on the back of rats resulted in a very severe acute reaction occurring after the second to fifth dose of 18 Gy. This was surprising since back skin, like tail skin, is less sensitive to large single doses of radiation than that of the foot. The late radiation reaction in the foot and tail of rats are compared and contrasted with other attempts to assess late effects in rodent skin and with late changes seen in pig skin.     

Change in the succinate dehydrogenase activity of peripheral lymphocytes in the rat in early periods following exposure to ionizing radiation

Activity of succinate dehydrogenase (SDH) in peripheral blood lymphocytes of albino mongrel rats was determined during an hour following gamma-irradiation. The highest SDH activity in blood lymphocytes (a 41 per cent increase) was registered 20-30 min following 75 Gy irradiation of the head. With a dose of 20 Gy the SDH response was twice as low. During 1 h following irradiation with a dose of 200 Gy the SDH activity exhibited a 10 per cent decrease.     

Dose-rate effects of mammary tumor development in female Sprague-Dawley rats exposed to X and gamma radiation

Mammary tumour development was followed in two experiments involving a total of 2229 female Sprague-Dawley rats exposed to various doses of X or gamma rays at different dose rates. The data for another 462 rats exposed to tritiated water in one of these experiments were also analyzed. The incidence of adenocarcinomas and fibroadenomas at a given time after exposure increased linearly in proportion to total radiation dose for most groups. However, no significant increase in adenocarcinomas was observed with chronic gamma exposures up to 1.1 Gy, and the increase in fibroadenomas observed with chronic gamma exposures at a dose rate of 0.0076 Gy h-1 up to an accumulated dose of 3.3 Gy was small compared to that observed after acute exposures. The incidence of all mammary tumors increased almost linearly with the log of dose rate in the range 0.0076 to 26.3 Gy h-1 for 3 Gy total dose of gamma rays. The effects of X rays appeared to be less influenced by dose rate than were the effects of gamma rays.     

Inhibitory effects of WR-2721 and cysteamine on tumor initiation in mammary glands of pregnant rats by radiation

We evaluated the effect of WR-2721 [S-2-(3-aminopropylamino)-ethylphosphorothioic acid] and cysteamine (2-mercaptoethylamine) on the development of radiation-induced mammary tumors in rats. Pregnant rats were treated with WR-2721 or cysteamine 30 min prior to whole-body irradiation with gamma rays from a (60)Co source at a dose of 1.5 or 2.6 Gy. Additional pregnant rats were given saline and then exposed to gamma rays at a dose of 0, 1.5 or 2.6 Gy as a control. All rats were implanted with pellets of diethylstilbestrol, a tumor promoter, 1 month after termination of nursing and were observed for 1 year to detect palpable mammary tumors. No mammary tumors developed in the saline-injected nonirradiated rats. However, when rats were irradiated with 1.5 or 2. 6 Gy after saline treatment, the incidence of mammary tumors was high (71.4 and 92.3%, respectively). Administration of WR-2721 or cysteamine prior to irradiation with 1.5 Gy significantly decreased the tumor incidence (23.8 and 20.8%, respectively). Tumor prevention by either agent was less effective at the higher dose. The appearance of the first mammary tumor occurred later in rats treated with WR-2721 or cysteamine than in the control rats. An increasing rate of adenocarcinoma in the control group was observed with increasing dose from 1.5 Gy up to 2.6 Gy. However, the development of adenocarcinoma did not increase after pretreatment with WR-2721 or cysteamine in rats irradiated with 2.6 Gy. Many of the mammary tumors that developed in the control rats were of the ER(+)PgR(+) type. Administration of WR-2721 produced no tumors of the ER(+)PgR(+) type. Cysteamine treatment increased the development of ER-negative tumors. The serum concentration of progesterone was significantly higher in rats treated with WR-2721 or cysteamine than in the control rats. On the other hand, the estradiol-17beta concentration was reduced by treatment with WR-2721, but not significantly compared to the control. WR-2721 and cysteamine had no effect on the prolactin concentration of the irradiated rats. The results suggest that administration of WR-2721 or cysteamine prior to the irradiation has a potent preventive effect on theinitiation phase during mammary tumorigenesis.     

Thymus lipids in continuously irradiated rats.

Male Wistar rats were irradiated continuously with a daily dose of 0.19 Gy (120 days), 0.57 Gy (90 days) and 0.96 Gy (35 days) of gamma rays. An other group of rats was irradiated continuously with graded doses of gamma rays, up to total exposures ranging from 3.83-19.15 Gy. Depending on both the daily dose and total exposure, there was a decrease in phospholipid content in the thymus which correlated well with thymus weight changes. The decrease in triacylglycerol content was a less reliable sign of radiation damage. The phospholipid content reflecting the patterns of organ cellularity is a valuable indicator of the extent as well as recovery from radiation-induced injury to the thymus.     

Effect of neutron and gamma radiation on physical endurance of rats in the swimming test

Three groups of adult male Wistar rats were exposed to neutrons (a single dose of 2 Gy) and gamma radiation (a continuous dose of 6 Gy delivered within 10.5 days) and a combination of both types of radiation. The physical fitness of irradiated and control rats was measured using a forced swimming test in the course and after the termination of the irradiation. A marked decrease in the physical fitness of all irradiated animals was followed by its normalization 3 weeks after irradiation.     

The influence of the exogenous melanin on the development of the second generation of the female Wistar rats exposed during the critical period of the pegnancy at the nonsterilizing doses of different rate means

The purpose of this study was to estimate the radio-protective activity of melanin for the reproductive status of Wistar rats. Wistar rats were exposed in utero either to the single gamma-irradiation on the tenth day of embryogenesis with the dose of 1 Gy or to the chronic gamma-irradiation with the total dose of 1 Gy during the first 10 days of embryogenesis. Such things like the ability of the rats to conceive, the embryogeny and early postnatal ontogeny of rat's posterity were studied. These doses of the radiation and the melanin did not produce the significant damages of the reproductive function of the survival offsprings of the first generation. The possible mechanisms of radio-protective effect of melanin on reproductive system of animals which have been exposed with the nonsterilizing doses at different mean dose rate were discussed.     

Islet function of the pancreas following irradiation

Function of islets of Langerhans of Wistar male rats was studied after irradiation of animals with different doses. The pancreas function was determined with regard to the incorporation of 65Zn into the gland tissues. Total-body irradiation (60Co) with the dose of 4.0 Gy somewhat increased the function of islets; at the dose of 8.0 Gy their function was transiently blocked, and at the dose of 15 Gy the function of islets of Langerhans was blocked completely.     

Effect of x-ray irradiation on the activity of key enzymes in heme biosynthesis and breakdown in the rat liver

The authors studied the effects of the whole-body x-irradiation on the activity of delta-aminolevulinate synthase and heme oxygenase in the liver of Wistar rats. The activity of delta-aminolevulinate synthase decreased to 81-49% of normal by the 1st-3d day after irradiation in a dose of 7 Gy followed by partial normalization of the enzyme activity by the 5th-7th day. The activity of heme oxygenase was over 2 times as increased by the 5th-7th day following irradiation in a dose of 7 Gy. Irradiation in a dose of 5 Gy did not alter the activity of heme oxygenase and caused a negligible reduction in the activity of delta-aminolevulinate synthase. During the most pronounced decrease in the rate of heme synthesis in the liver of irradiated rats, there was an elevation in the level of "free" heme (measured by the degree of tryptophane pyrrolase saturation with heme). This attests to a possible lowering of the rate of heme utilization in the synthesis of heme. A possible role of the effects described in the irradiation-induced decrease in the content of cytochrome P-450 in the animals' liver.     

Enhanced body radioresistance resulting from the transfusion of autologous blood irradiated with low doses of ionizing radiation]

Preliminary administration of autogenic blood irradiated in vitro with ionizing radiation in small doses of 0.05, 0.3 or 0.5 Gy resulted in a pronounced increase in the radioresistance of mice [correction of rats] subsequently irradiated in a dose of 9 Gy. The optimum was autotransfusion of blood irradiated in a dose of 0.3 Gy a day or 10 days prior to the total irradiation which increased the survival rate of experimental animals to 80% while, in control groups, the survival rate was only 10%.     

Resistance to reinfection in rats induced by irradiated metacercariae of Clonorchis sinensis

A study was made to observe the association between the resistance to reinfection induced by irradiated metacercariae (MC) of Clonorchis sinensis and antigen specific Th1- and Th2-type cytokine productions in rats. Rats were infected with 20 MC of C. sinensis, previously exposed to a single dose of gamma irradiation, which varied from 0 to 100 Gy. All of them, single dose of 12 Gy showed higher IgG antibody titer with lowest worm recovery. Thus, 50 MC were used to challenge infection in rats previously infected with 20 MC irradiated at 12 Gy and the highest resistance to challenge infection was observed. The results of lymphocyte proliferation with specific antigen, ES Ag were shown no difference of proliferative responses as compared with primary and challenge infection at 12 Gy irradiation dose. In the case of cytokines production were observed that interferon (IFN-gamma) and interlukin (IL-2) were significantly enhanced, while IL-4 and IL-10 was almost unchanged to make comparison between primary and secondary infection at 12 Gy irradiation dose. In conclusion, the single dose of 12 Gy could be adopted for induction of the highest resistance to challenge infection. Up-regulation of Th1 type cytokines, IFN-gamma and IL-2 may be affected to develop vaccine by irradiated MC.     

Synthesis of lipids in the thymocytes of irradiated rats

During the first two hours following whole-body gamma-irradiation of rats with a dose of 7.5 Gy, the content of free cholesterol, phosphatidylcholine and phosphatidylethanolamine in the thymus decreases. Incorporation of 2-14C-acetate into cholesterol and fatty acids of thymus phospholipids in vitro is inhibited. At a dose of 4 Gy, incorporation of 2-14C-acetate into cholesterol and total lipids of thymocytes is activated.     

Studies of long-term continuous irradiations using daily doses ranging from 0.07 to 0.30 Gy on the B lymphoid system of the rat

The effects of a continuous exposure to cobalt gamma rays administered to rats at a daily dose of 0, 0.07, 0.12, 0.20 or 0.30 Gy for a period of up to 90 or 135 days, have been observed on their B lymphocyte populations and on their immunoglobulin serum levels. The effects increase with the daily dose and the duration of irradiation. At a daily dose of 0.07 Gy, no clear effect was observed. The depletion was almost negligible after 30 days at a daily dose of 0.12 Gy, but visible after all other doses and durations. However, a clear difference in susceptibility was observed between the marginal zone B compartment and the follicular one, the former being much more affected by the radiation than the second.     

Radio-protective effects of melatonin against irradiation-induced oxidative damage in rat peripheral blood

During radiotherapy, ionizing irradiation interacts with biological systems to produce free radicals, which attacks various cellular components. The hematopoietic system is well-known to be radiosensitive and its damage may be life-threatening. Melatonin synergistically acts as an immunostimulator and antioxidant. In this study we used a total of 120 rats with 20 rats in each group. Group 1 did not receive melatonin or irradiation (Control group), Group 2 received only 10 mg/kg melatonin (Mel group), Group 3 exposed to dose of 2 Gy irradiation (2 Gy Rad group), Group 4 exposed to 8 Gy irradiation (8 Gy Rad group), Group 5 received 2 Gy irradiation plus 10 mg/kg melatonin (Mel +2 Gy Rad group) and Group 6 received 8 Gy irradiation plus 10 mg/kg melatonin (Mel+8 Gy Rad group). Following exposure to radiation, five rats from each group were sacrificed at 4, 24, 48 and 72 h. Exposure to different doses of irradiation resulted in a dose-dependent decline in the antioxidant enzymes activity and lymphocyte count (LC) and an increase in the nitric oxide (NO) levels of the serum. Pre-treatment with melatonin (10 mg/kg) ameliorates harmful effects of 2 and 8 Gy irradiation by increasing lymphocyte count(LC) as well as antioxidant enzymes activity and decreasing NO levels at all time-points. In conclusion 10 mg/kg melatonin is likely to be a threshold concentration for significant protection against lower dose of 2 Gy gamma irradiation compared to higher dose of 8 Gy. Therefore, it seems that radio-protective effects of melatonin are dose-dependent.     

Characteristics of the metabolism and gonadal action in mice of tritium-labelled deoxycytidine

The levels of 3H-deoxycytidine binding in mice and rats were shown to depend on the amount of the carrier and the routes of administration, and the dynamics of its retention, on the dose and schedule of its administration. As estimated by the criterion of the testis mass decrease the 3H-deoxycytidine dose of 37 kBq/g is equivalent to gamma-radiation dose of 0.06 Gy. The coefficient of 3H-deoxycytidine absorption from the digestive tract of mice and rats is 2-10 times as high as that of 3H-thymidine, while both compounds administered to rats transcutaneously have the same absorption coefficients amounting to 0.02.     

The effective dosage as the stimulating exposure in fractionated gamma irradiation

The study of early neurological disturbances (END) in rats after fractionated gamma irradiation with doses of 37.5-225 Gy at dose rate of 30.11 Gy/min has demonstrated that the initial response of animals to pulse ionizing radiation is a function of the electric charge induced by ionizing radiation. A change in the probability of occurrence of each of the END symptoms, with the increased intervals between exposures, is merely an indirect indication of the eliminating mechanisms and is intricately connected with the irritating charge value. The period of dose half-elimination in 16 min. The threshold effective dose rate leading to END is of the order of 2.12 Gy/min. The proposed empiric relationships permit to correlate the probability of END symptom occurrence with the continuous quantitative parameter of fractionated irradiation, that is, with an effective dose as an analogue of the irritating effect.     

Hypertension after bilateral kidney irradiation in young and adult rats

The mechanism of a rise in blood pressure after kidney irradiation is unclear but most likely of renal origin. We have investigated the role of the renin-angiotensin system and dietary salt restriction in the development of systolic hypertension after bilateral kidney irradiation in young and adult rats. Three to 12 months after a single X-ray dose of 7.5 or 12.5 Gy to both kidneys of young and adult rats, the systolic blood pressure (SBP) and plasma renin concentration (PRC) were measured regularly. A single X-ray dose of 12.5 Gy caused a moderate rise in SBP and a slight reduction in PRC in both young and adult rats. A dose of 7.5 Gy did not significantly alter the SBP or PRC during the follow-up period of 1 year. In a second experiment, the kidneys of young rats received an X-ray dose of 20 Gy. Subsequently, rats were kept on a standard diet (110 mmol sodium/kg) or a sodium-poor diet (10 mmol sodium/kg). On both diets, SBP started to rise rapidly 3 months after kidney irradiation. Sodium balance studies carried out at that time revealed an increased sodium retention in the irradiated rats compared to controls on the same diet. In rats on a low sodium intake, there was neither a delay nor an alleviation in the development of hypertension. Compared to controls, the PRC tended to be lower in irradiated rats up to 4 months after irradiation. Subsequently, malignant hypertension developed in all 20 Gy rats, resulting in pressure natriuresis, stimulating the renin-angiotensin system. Our findings indicated that hypertension after bilateral kidney irradiation was not primarily the result of an activation of the renin-angiotensin system. Although there were some indications that sodium retention played a role, dietary sodium restriction did not influence the development of hypertension.