The effects of a fractionated gamma irradiation on life shortening and disease incidence in BALB/c mice

BALB/c male mice (12 weeks old) were exposed to a single or fractionated exposure of 137Cs gamma rays. The fractionated dose was split into 10 equal doses delivered at an interval of 1 day. The causes and possible causes of spontaneous death were ascertained by autopsy and histological examination, and the data were treated by competing risk analysis. Life shortening followed a linear dose dependency and was about the same for fractionated (38.1 +/- 3.1 days/Gy) as for single (46.2 +/- 4.3 days/Gy) exposure. Death from tumor disease was enhanced and that from nonstochastic lung and kidney diseases was reduced after fractionated compared to single exposure.     

Concentrations and antioxidative activity of anserine and carnosine in poultry meat extracts treated with demineralization and papain

Anserine and carnosine found in animal skeletal muscle are capable of inhibiting the catalysis of lipid oxidation by heme and non-heme iron. A demineralization technique and a proteolytic enzyme (papain) were used in this research in order to reduce the levels of proxidants while maintaining high levels of anserine and camosine in poultry (chicken, duck and turkey) meat extracts. Undemineralized poultry meat extracts contained larger amounts of anserine, camosine, heme and non-heme iron (p < 0.05) than did demineralized poultry meat extracts. Both undemineralized and demineralized breast meat extracts of chicken, duck and turkey contained higher concentrations of anserine and camosine, but lower amounts of heme and non-heme iron than did thigh meat extracts. In chicken, duck and turkey meat (breast and thigh) extracts (undemineralized and demineralized), the anserine concentrations were greater (p < 0.05) than the camosine concentrations. The hydrogen-donating ability of undemineralized and demineralized chicken breast meat extracts was not significantly different (p > 0.05): however, demineralized chicken breast meat extracts showed higher (p < 0.05) ferrous chelating ability than did undemineralized meat extracts. The concentrations of anserine, camosine, heme and non-heme iron in chicken breast meat extracts increased (p < 0.05) with the addition of papain (1%) to the meat mixture before extraction. Heme and non-heme iron in the chicken breast meat extracts increased as the reaction time for papain increased from 30 to 120 min, but the concentrations of anserine and camosine were not significantly affected by the longer reaction time for papain. The hydrogen-donating ability and ferrous chelating ability of demineralized chicken breast meat extracts were not significantly affected by papain. The ratios of carnosine/anserine were very specific in the chicken, duck and turkey meat extracts (breast and thigh); and the turkey meat extracts had lower (p < 0.05) camosine/anserine ratios than did the chicken and duck meat extracts. The camosine/anserine ratios of undemineralized and demineralized poultry meat extracts were not significantly different (p > 0.05). This suggests that the carnosine/anserine ratios of undemineralized chicken (0.62 - 0.80), duck (0.75 - 0.77) and turkey (0.15 - 0.16) meat extracts could be used to estimate the single meat species in uncooked or cooked meat products.     

Life shortening and disease incidence in BALB/c mice following a single d(50)-Be neutron or gamma exposure

Male BALB/c mice, 12 weeks old, were given a single exposure of either 137Cs gamma rays or d(50)-Be neutrons at a dose rate of 3 Gy/min. The animals were kept until death, and causes of death or possible causes of death were ascertained by autopsy and histology. The data were evaluated by competing risk methods. The survival time dose-effect curve for both types of exposure was linear and did not differ significantly (slopes: 55.8 +/- 4.0 days/Gy for neutrons and 46.2 +/- 4.3 days/Gy for gamma rays). The incidence of different diseases also was similar for both groups except that more carcinomas, sarcomas, and myeloid leukemias seemed to occur after neutron exposure and that nonstochastic lung and kidney diseases seemed to arise at lower doses.     

Dependence of the therapeutic effectiveness of interleukin-1beta on the time of the drug administration after irradiation of mice

In experiments on mice F1(CBA x C57BL/6) the dependence of 30th days survival on the time of betaleukin (medicine form of interleukin-1 beta) administering after exposure to 7.5 Gy whole body gamma-irradiation from 137Cs (approximately DL80/30) was studied. Betaleukin was injected subcutaneously in dose 25 mcg/kg 0.2, 1, 3, 6 and 24 h after the exposure. The highest therapeutic effect took place in case of 0.2 h interval, then it dropped but was slightly expressed at 1 h. The hemopoiesis condition was studied in 7 or 9 days after the mice exposure to 6 Gy and betaleukin administering 1 h later in dose 25 or 50 mcg/kg. The positive effect on granulopoiesis beginning from the level of CFU-GM was observed. There were analyzed the reasons of weaker betaleukin effect and shorter period of its effectiveness after exposure in comparison with literature data regarding IL-1.     

Effective bioconversion of farmed chicken products by black soldier fly larvae at commercially relevant growth temperatures

Global population growth and an increasing demand for meat has driven the intensification of livestock production. On poultry farms, the accumulation of waste such as faeces, carcasses and unsellable eggs creates environmental and health hazards that need to be mitigated. The larvae of the black soldier fly (Hermetia illucens; BSFL) offer a potential solution to the problems of waste management on poultry farms. BSFL consume large quantities of organic waste and convert it into larval biomass, which can then be processed for use as livestock feeds or biofuels. This makes BSFL an ideal candidate for value-added waste management on chicken farms. Here, we examined the development and nutrient profile of BSFL given five different diet treatments: poultry feed (control), chicken meat, chicken egg, chicken manure and a mixture of equal parts chicken meat, egg and manure. Chicken meat, egg and mixed diets were all found to be suitable feedstocks for BSFL, but the manure-only treatment was associated with a high failure rate of larval development. Mixing manure with other poultry waste streams ameliorated the negative impacts of manure on BSFL. Larvae reared on chicken meat, egg and the mixed diet had equal or higher mean crude protein (CP) (39.9%, 33.8% and 31.5%, respectively) and crude lipid (CL) contents (30.1%, 29.00% and 28.7%, respectively), compared with BSFL reared exclusively on chicken feed (CP: 30.9%, CL: 23.8%), demonstrating the suitability of these waste-stream diets for the potential animal feed quality of the BSFL. We discuss how BSFL bioconversion could be implemented to address environment management issues on poultry farms.     

Mitochondrial DNA mutation frequencies in experimentally irradiated compost worms, Eisenia fetida

The compost worm Eisenia fetida is routinely used in ecotoxicological studies. A standard assay to assess genetic damage in this species would be extremely valuable. Since mitochondrial DNA (mtDNA) is known to exhibit an increased mutation rate following exposure to ionising radiation we assessed the validity of a mtDNA-based assay for measuring increases in mutation rate in laboratory-irradiated compost worms. To this end the mutation frequency in the mtDNA of the compost worm E. fetida was quantified following in vivo gamma-irradiation of adult worms in three dose groups. Five adult worms exposed to 1.4 mGy/h for 55 days (total dose 1.85 Gy), five adult worms exposed to 8.5 mGy/h for 55 days (total dose 11.22 Gy) and five adult control worms were used to assess the effect of irradiation on mtDNA mutation induction. DNA samples extracted from irradiated adult worms were used in high-fidelity PCR of a 486 bp region of mtDNA spanning the ATPase 8 gene, chosen for its high spontaneous mutation rate. PCR products were cloned and sequenced to identify mutations, with 89-102 clones successfully sequenced per individual. A significant elevation in mtDNA mutation frequency (p=0.032) was seen in worms exposed at the higher dose rate (8.5 mGy/h, total dose 11.22 Gy; mutation frequency 27.98+/-4.85 x 10(-5)mutations/bp) in comparison to controls (mutation frequency 12.68+/-3.06 x 10(-5)mutations/bp), but no elevation in mutation frequency (p=0.764) was seen for the lower dose rate (1.4 mGy/h, total dose 1.85 Gy; mutation frequency 13.74+/-1.29 x 10(-5)mutations/bp) compared with controls. This indicates that although the technique has the potential to detect an elevation in mutation frequency, it does not have sufficient sensitivity at the doses likely to be encountered in environmental monitoring scenarios.     

谷氨酰胺对低剂量电离辐射损害的保护作用

观察小剂量电离辐射条件下大鼠补充谷氨酰胺(Gln)对体内谷胱甘肽(GSH)代谢的影响。SD雄性大鼠受照射后经饲料补充2%Gln。照射源为60Co;剂量率6×10-2Gy/h,1h/d,5d/周,累积剂量1.5Gy。与对照组相比,受照射大鼠睾丸重量降低,精子畸变率增高,肝脏GSH含量降低,外周血白细胞计数降低,血清Gln及Glu+Gln含量降低,差异具有显著性,补充Gln则与对照组无明显差异。表明小剂量电离辐射导致大鼠出现可逆性损害,机体的Gln需求有所增加,补充Gln对大鼠的GSH代谢有一定益处。     

Methodology for an assessment of derived radiation levels for agrocenoses

Radiation protection of agrarian ecosystems should be considered as an integral part of a system for radiation protection of environment, with a special concern to agroecosystems' features. A methodology is proposed for an assessment of maximum permissible doses of radiation impact for agrocenoses based on an unified analysis of available data about effects of radiation in cultivated plants. It is considered as a component of radiation protection system for agricultural ecosystems. Critical doses and dose rates are estimated for crops under different exposure situations. It is shown that doses that could result in decreasing indexes of productivity and survival for main crops below 50% are unlikely up to 170-200 Gy and 15-17 Gy at an acute exposure of dormant seeds and vegetative plants, correspondingly. At chronic exposure, above 10% loss of productivity in crops is not expected at dose rates below 3-10 mGy/h.     

Mutations and chromosomal aberrations in hMTH1-transfected and non-transfected TK6 cells after exposure to low dose rates of gamma radiation

The aim of the present study was to analyse the dose rate effect of gamma radiation at the level of mutations, chromosomal aberrations, and cell growth in TK6 cells with normal as well as reduced levels of hMTH1 protein. TK6 cells were exposed to gamma radiation at dose rates ranging from 1.4 to 30.0 mGy/h (chronic exposure) as well as 24 Gy/h (acute exposure). Cell growth, frequency of thymidine kinase mutants, and of chromosomal aberrations in painted chromosomes 2, 8, and 14 were analysed. A decline in cell growth and an increase in unstable-type chromosomal aberrations with increasing dose rate were observed in both cell lines. A dose rate effect was not seen on mutations or stable-type chromosomal aberrations in any of the two cell lines. Reduction in the hMTH1 protein does not influence the sensitivity of TK6 cells to gamma radiation. This result fits well with data of others generated with the same cell line.     

Reaction of posterity of two generations after exposure of pregnant Wistar rats to low dose irradiation during the period of fetus formation. Development of the first generation posterity

Whole-body single exposure of female Wistar rats to 0.25, 0.5 and 1 Gy of gamma-rays (dose rate of 0.03 cGy/s) on the 10th day of pregnancy (a period of formation of the reproductive system in fetus) was carried out. To study irradiation consequences on the antenatal and postnatal development of the progeny 220 females, 700 19-day-old fetuses and about 1100 young rats were examined. The antenatal development of the progeny of the first generation was significantly impaired after the exposure to 1 Gy. However even less radiation doses resulted in a pronounced tendency to higher rates of intrauterine death and a lower number of live fetuses. Significant deviatins in the postnatal development of the first generation progeny were found after the exposure to 0.5 Gy, although the exposure to 0.25 Gy led to a higher rate of postnatal death and a less number of newborns in the litter.     

Changes after irradiation in the number of mitotic cells and apoptotic fragments in growing mouse hair follicles and in the width of their hairs

The hair follicle or its differentiated product, the hair, which represents the linear historical record of the follicular proliferative activity, could provide a biological dosimeter of value for dose distribution determinations after accidental exposure. Here we present some further studies on irradiated mouse hair follicles and hair, and discuss the difficulties in obtaining similar data for humans. The incidence of cell death in the follicles has been shown elsewhere to be maximum 12 h after irradiation, and it increases with dose. Here we confirm that doses of 0.2-0.4 Gy can be readily detected. We show here that there is only a little more cell death in the larger follicles even though they contain many more cells and mitotic figures. About one-third of all the dead cell fragments in a follicle can be seen in a good longitudinal follicle section. Mitotic activity declines progressively with dose in the large follicles, which start with more mitotic cells, showing the dose-dependent changes most readily. The dead cells are morphologically identical to apoptotic cells at the level of the light microscope, and they fragment into several bodies, the number of which increases with dose. The total number of apoptotic bodies or fragments in whole large follicles increases almost 100-fold over a range of 1.3 Gy (from 0.2 to 1.5 Gy) and about tenfold over the range 0.2-0.5 Gy. The estimated number of dead (apoptotic) cells increases about sevenfold over the same 1.3-Gy range. The width of the middle portion of the broadest, awl, hairs measured 12 days after irradiation decreases with increasing dose. About 80% of the hairs show an obvious reduction in width after 2 Gy and the effects of a dose of about 1 Gy can be detected. The width of the hair is reduced by 10-14% per Gy. A comparison has been made between BDF1 (black) and BALB-c (albino) mice. The large follicles contain similar numbers of mitotic cells, but the BALB-c mice are more sensitive both in terms of the radiation-induced apoptosis and in terms of a reduction in awl hair width.     

Effects of low dose rate (0.003-0.025 Gy/h) chronic X-irradiation on radioresistant and radiosensitive L5178Y mouse lymphoma cells

Cultures of radioresistant (LY-R) and radiosensitive (LY-S) strains of L5178Y mouse lymphoma cells were exposed continuously to X-rays delivered at dose rates ranging from 0.003 to 0.025 Gy/h for up to 35 days. Populations of both strains proliferated actively during the exposure, but the growth rates were reduced in a dose rate-dependent manner. The reduction of growth rate occurred for strain LY-S earlier during the exposure and at lower dose rates than for strain LY-R. The survival (as measured by colony forming ability) of strain LY-R was affected only slightly at all dose rates applied. For strain LY-S, a decrease in the surviving fraction was observed in the initial part of the exposure. This decrease was followed by a plateau and eventually by an increase, in some cases to values close to the control level. The increase in the surviving fraction indicated that the radioresistance of the exposed LY-S cells had increased. This pattern was particularly clear for dose rates greater than 0.014 Gy/h. The pre-irradiated cells exhibited radioresistance when exposed to acute X-radiation after termination of the chronic exposure. The increase in radiation resistance was stable for at least 70 days after termination of the protracted exposure. These results show that mutagenic and/or selective phenomena leading to an increase in radiation resistance of mammalian cells can be caused by protracted exposures to X-rays at dose rates permitting active proliferation.     

Upper dose thresholds for radiation-induced adaptive response against cancer in high-dose-exposed, cancer-prone, radiation-sensitive Trp53 heterozygous mice

Trp53 heterozygous mice are radiation-sensitive and cancer-prone. Groups of 7-8-week-old female Trp53 heterozygous mice were exposed to 4 Gy of 60Co gamma radiation at high (0.5 Gy/min) or low (0.5 mGy/min) dose rate. Other groups received 10 or 100 mGy at low dose rate 24 h prior to the 4-Gy dose. Tumor frequency and latency were measured over the animals' life span. Exposure to 10 mGy prior to 4 Gy resulted in a small (approximately 5%) but significant life-span regain and increased latency (approximately 9%) for all malignant tumors taken together, but 100 mGy further reduced life span slightly (approximately 7%). Latency responses were tumor type-specific. The prior 10-mGy exposure resulted in a small (approximately 7%) regain in latency for lymphomas but no change in latency for spinal osteosarcomas. Increasing the adapting dose to 100 mGy eliminated the increase in lymphoma latency and further reduced life span (approximately 8%). A 10-mGy dose prior to 4 Gy at low dose rate had no effects. Adapting exposures had no significant effect on tumor frequency. We conclude that a single low dose induced a small protective response in vivo in Trp53+/- mice, reducing the carcinogenic effects of a subsequent large, high-dose-rate exposure by increasing tumor latency. The upper dose threshold at which low-dose protective effects gave way to detrimental effects was tumor type-specific, as found previously for spontaneous tumors in these same cancer-prone mice (Radiat. Res. 159, 320-327, 2003). However, the upper dose thresholds appear to be lower (below 100 mGy) for radiation-induced tumors than for the same tumors appearing spontaneously.     

Radiation-induced malformations after exposure of murine germ cells in various stages of spermatogenesis

We studied radiation effects in day 19 fetuses of the mouse strain 'Heiligenberger' after exposure (2.8 Gy, 137 Cs gamma rays, dose rate 0.28 Gy/h) of their fathers. We observed an increased lethality (exclusively due to preimplantation death and early resorptions) after exposure of all stages of spermatogenesis with the exception of early spermatogonia. In addition, there was a significant increase in the frequency of malformed fetuses (gastroschises only); this increase was observed primarily after exposure of the meiotic stages.     

The combined effects of dietary supplements and low-dose-rate high-LET radiation on mice in vivo

The purpose of this study was to investigate the combined actions of food supplements and lowdose-rate high-LET radiation on radiosensitivity, induction of the adaptive response, and tumor growth in SHK mice in vivo. The animals were irradiated with 0.11 Gy (0.005 Gy/day) of low-dose-rate high-LET radiation behind the concrete shield of a 70 GeV proton accelerator (Protvino, Moscow oblast). Four groups of the mice were fed with selected products (soy meat, buckwheat, lettuce leaves, and a drug based on cod-liver oil) during the entire irradiation period (22 days). The results of the study indicate that the mice with diets containing soy meat, buckwheat, and lettuce leaves in contrast to those fed with a diet containing cod-liver oil had reduced sensitivity to X-radiation at a dose rate of 1.5 Gy and a significant slowdown in the growth of the Ehrlich carcinoma. The combined effect of high-LET radiation and the food supplements mentioned above (except for the cod-liver oil) reduced the sensitivity of the mice to the irradiation at a dose rate of 1.5 Gy, induced the adaptive response, and caused a decrease in the growth rate of the Ehrlich carcinoma in contrast to the mice that were only irradiated with high-LET radiation.     

Cerebrovascular diseases in the cohort of workers first employed at Mayak PA in 1948-1958

The incidence of and mortality from cerebrovascular diseases (CVD) have been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2000. Information on external γ-ray doses is available for virtually all of these workers (99.9%); the mean total γ-ray dose (± SD) was 0.91 ± 0.95 Gy (99th percentile 3.9 Gy) for men and 0.65 ± 0.75 Gy (99th percentile 2.99 Gy) for women. In contrast, plutonium body burden was measured only for 30.0% of workers; among those monitored, the mean cumulative liver dose from plutonium α-particle exposure (± SD) was 0.40 ± 1.15 Gy (99th percentile 5.88 Gy) for men and 0.81 ± 4.60 Gy (99th percentile 15.95 Gy) for women. A total of 4418 cases of CVD, including 665 cases of stroke, and 753 deaths from CVD, including 404 deaths from stroke, were identified in the study cohort. Having adjusted for non-radiation factors, there were statistically significant increasing trends in CVD incidence but not mortality with both total external γ-ray dose and internal liver dose. Much of the evidence for increased incidence in relation to external dose arose for workers with cumulative doses above 1 Gy. Although the dose response is consistent with linearity, the statistical power to detect non-linearity at external doses below 1 Gy was low. CVD incidence was statistically significantly higher among workers with a plutonium liver dose above 0.1 Gy. There was a statistically significant increasing trend in incidence with increasing internal dose, even after adjusting for external dose, although the trend estimates differed between workers at different plants. The risk estimates for external radiation are generally compatible with those from other large occupational studies, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors.     

The effect of ionizing radiation on lipid metabolism in lymphoid cells

Lipid metabolism was studied in lymphoid tissues of rats after whole body irradiation with doses producing damage of different degrees to lymphoid cells (4-10 Gy). The content of free cholesterol, cholesterol esters, and total phospholipids was determined in peripheral blood lymphocytes and thymocytes 1-2 h after exposure. Simultaneously, the rate of in vitro incorporation of 2 14C-acetate into total lipids, phospholipids, and cholesterol of lymphoid cells was estimated. It was shown that exposure of rats to ionizing radiation caused activation of lipogenesis. Cholesterol synthesis was activated after a dose of 4 Gy and decreased with increasing dose.     

Influence of dose rate on survival time for 239PuO2-induced radiation pneumonitis or pulmonary fibrosis in dogs.

Beagle dogs were exposed once or repeatedly to 0.75-microns-diameter monodisperse aerosols of 239PuO2 by pernasal inhalation. The dogs that were exposed once received alveolar depositions (+/- standard deviation) of 3.9 +/- 1.9 kBq/kg body mass and accumulated doses of 23 +/- 8 Gy to the lung before death at 5.4 +/- 1.7 years after exposure. Dogs exposed repeatedly received a total alveolar deposition of 5.3 +/- 0.9 kBq/kg body mass during 7 to 10 semiannual exposures and accumulated doses of 22 +/- 5 Gy to the lung before death at 4.9 +/- 0.7 years after first exposure. Clearance of the plutonium from the lung in the dogs exposed repeatedly was slower than in the dogs exposed once. All dogs in the repeated-exposure study and all but one dog in the single-exposure study died from radiation effects. Pulmonary fibrosis accounted for 72% of the radiation-related deaths in the single-exposure study and 87% in the repeated-exposure study. The remaining dogs died with pulmonary cancer. Based on total cumulative radiation dose, the times after exposure to death from radiation pneumonitis and pulmonary fibrosis were not significantly different for single and repeated exposures. Thus dose rate does not appear to be an important factor in predicting death from radiation pneumonitis or pulmonary fibrosis for dogs inhaling 239PuO2.     

Effects of prolonged low-intensity irradiation on organ weight of the male rat reproductive system

The effects of prolonged irradiation at accumulated doses from 0.5 to 6.0 Gy (dose rate 3.03 cGy/day) on reproductive organs' weight (testes, epididymises, seminal vesicles, prostate) of male rats starting from the early ontogenetic period were studied. On the first day after the irradiation with 1.0 Gy dose a significant loss of the weight in testes and epididymises was revealed. This leaded to the marked atrophy of the organs with the increase of the radiation dose. Long-term restoration of the weight of testes and epididimyses was registered. It was not completed during three months after radiation exposure at 2.0 Gy and higher doses for epididimyses and 4.0-6.0 Gy for testes. The respective changes in the seminal vesicles and prostate weight were less pronounced and had more complicated character. However in the distant period (30-90 days of postreatment) after exposure to 2.0 Gy these parameters were noticeably decreased.     

Adaptive response of the chicken embryo to low doses of x-irradiation

Chicken embryos were x-irradiated in ovo with 5–30 cGy (=priming dose) at the 13th–15th day of development. After 3–48 h, brain- and liver-cell suspensions were x-irradiated in vitro with (challenge) doses of 4–32 Gy. Significantly less radiation damage was observed when the radiation response was measured by scheduled DNA synthesis, nucleoid sedimentation and viscosity of alkaline cell lysates 12–36 h after the priming exposure. In vivo, pre-irradiation with 10 cGy enhanced regeneration as evidenced by the DNA content of chicken embryo brain and liver 24 h following a challenge dose of 4 Gy. From nucleoid sedimentation analyses in brain and liver cells immediately after irradiation with 16 Gy and after a 30-min repair period in the presence of aphidicolin, dideoxythymidine and 3-aminobenzamide or in the absence of these DNA repair inhibitors, it is concluded that a reduction of the initial radiation damage is the dominant mechanism of the radio-adaptive response of the chicken embryo. Sedimentation of nucleoids from ethidium bromide (EB) (0.75–400 µg/ml)-treated cells suggests a higher tendency of radio-adapted cells to undergo positive DNA supercoiling in the presence of high EB concentrations.