The effect of ultraviolet irradiation on the protozoan Tetrahymena pyriformis

A number of trials was conducted to test the effect of ultraviolet radiation on the protozoan Tetrahymena pyriformis, strain W. The material was cultivated in a culture medium and in a deficient experimental medium, the radiation flux being 90 to 5400 J/m2 in the logarithmic and stationary stages of population growth. As found, the culture medium has a protective effect against ultraviolet radiation, owing to an increased peptone content. The cells in the stationary stage of growth are more resistant to ultraviolet radiation than cells in the logarithmic stage of growth. The studied intensities of radiation did not damage the nutrients contained in the medium.     

Radiation up-regulates the expression of VEGF in a canine oral melanoma cell line

To evaluate radiosensitivity and the effects of radiation on the expression of vascular endothelial growth factor (VEGF) and VEGF receptors in the canine oral melanoma cell line, TLM 1, cells were irradiated with doses of 0, 2, 4, 6, 8 and 10 Gray (Gy). Survival rates were then determined by a MTT assay, while vascular endothelial growth factor receptor (VEGFR)-1 and -2 expression was measured by flow cytometry and apoptotic cell death rates were investigated using an Annexin assay. Additionally, a commercially available canine VEGF ELISA kit was used to measure VEGF. Radiosensitivity was detected in TLM 1 cells, and mitotic and apoptotic cell death was found to occur in a radiation dose dependent manner. VEGF was secreted constitutively and significant up-regulation was observed in the 8 and 10 Gy irradiated cells. In addition, a minor portion of TLM 1 cells expressed vascular endothelial growth factor receptor (VEGFR)-1 intracellularly. VEGFR-2 was detected in the cytoplasm and was down-regulated following radiation with increasing dosages. In TLM 1 cells, apoptosis plays an important role in radiation induced cell death. It has also been suggested that the significantly higher VEGF production in the 8 and 10 Gy group could lead to tumour resistance.     

The effect of heat processing on the biological values of selected foods using the amoeba Tetrahymena pyriformis as a test agent

Tetrahymena pyriformis strain W was used as the testing subject for the determination of the biological value of selected eatables. The eatables were investigated at a 2% concentration. Part of the test eatables was subjected to heat treatment at 0.1 MPa and at the temperature of 121 degrees C for 120 minutes. Heat treatment under these conditions was found to reduce the biological value of the eatables.     

The effect of dichlorvos and metathion on selected enzymes of the amoeba Tetrahymena pyriformis

The effect of dichlorvos and metathion was studied as exerted on acetylcholinesterase activity in the protozoan Tetrahymena pyriformis. In dichlorvos, the highest enzyme activity inhibition was obtained after 30 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 1.22 mg per litre. As to metathion, the highest enzyme activity inhibition was obtained after 60 minutes. A 50% inhibition of the enzyme activity was recorded at the dose of 879.2 ng per litre. One hour after exposure to this dose, almost 75% inhibition of the activity of the enzyme was recorded. The determination of acetylcholinesterase activity increases the sensitivity of the bioassay for organophosphates with the use of the Tetrahymena pyriformis protozoan. Dichlorvos was studied for its action at supratoxic doses (50.0, 100.0 and 150.0 mg per litre) and it was found that lactate dehydrogenase activity was almost completely suppressed; the inhibition of alanine aminotransferase was pronounced. A weaker activity inhibition was recorded in aspartate aminotransferase, alkaline and acid phosphatase; the activity of alpha-amylase increased. No dependence on dosage was demonstrated.     

A biological method for the determination of mycotoxins--Tetrahymena pyriformis

The toxic action of selected mycotoxins on a biological subject was tested in the protozoan Tetrahymena pyriformis. The following toxins were tested: toxin T-2 at doses from 1.52 micrograms to 100.0 mg per litre of medium, ochratoxin A at doses from 12.21 micrograms to 800.0 mg per litre of medium, and rubratoxin B at doses from 12.21 micrograms to 800.0 mg per litre of medium. In toxin T-2 the LD100 was found to be about 390.63 micrograms and LD50 about 48.83 micrograms per litre of medium. In ochratoxin A the LD100 was about 25.0 mg and LD50 about 3.13 mg per litre of medium. In rubratoxin B the LD100 was about 200.0 mg and LD50 about 25.0 mg per litre of medium.     

The effect of pesticides on the protozoan Tetrahymena pyriformis

The toxic effect of the following pesticides was examined: metathion (doses from 1.49 micrograms to 100.0 g per litre of medium), phenmedipham (doses from 24.42 micrograms to 400.0 mg per litre of medium), gamma-hexachlorocyclohexane (doses from 122.07 micrograms to 250.0 mg per litre of medium), and chlormequat (doses from 305.16 micrograms to 20.0 g per litre of medium). The tests were performed on the protozoan Tetrahymena pyriformis. The LD50 of metathion was found to be 8.94 micrograms per litre and the LD100 ranged from 23.84 to 47.68 micrograms per litre. In phenmedipham the LD50 ranged from 12.5 to 25.0 mg per litre and its LD100 was above 400.0 mg per litre. The LD50 of gamma-hexachlorocyclohexane is 976.56 micrograms per litre and LD100 about 7.91 mg per litre. The LD50 of chlormequat ranged from 312.5 to 625.0 mg per litre and LD100 was about 20.0 g per litre of medium.     

The effect of graduated radiation doses on the follicular apparatus of the ovaries and the adenohypophysis in sheep

Gradually increased radiation doses were applied directly to the ovaries of laparotomized ewes. The effect of these doses was studied as exerted on the qualitative and quantitative changes in the follicular apparatus of the ovaries and adenohypophysis of ewes in anoestrus and upon the recovery processes later on after irradiation. The ovaries irradiated with the dose of 4.79 Gy were found to be heavier when examined after some time from irradiation. The 10th and 30th day from irradiation the number of tertiary follicles decreased, the 100th day from irradiation their number increased to a four-fold level, as compared with the 10th day. Adenohypophysis showed a gradual growth of the number of PAS-positive cells. After the irradiation of ovaries with the dose of 9.57 Gy the ovaries showed the lowest rate of damage on the 10th day from irradiation; the 30th and 100th day from irradiation all the present tertiary follicles were in the state of atresia. In comparison with the control group, the amount of gonadotropic cells of adenohypophysis gradually increased, recovering from a rapid drop after irradiation. When the ovaries were irradiated with the dose of 19.14 Gy, all the tertiary follicles were in the state of atresia and the number of PAS-positive cells of adenohypophysis was lower in comparison with the control group.     

Preparation of fowl testes as recipient organs to germ-line chimeras by means of gamma-radiation

1. The aim of the study was to investigate the possibility of preparing adult fowl testes for the production of exogenous germ-lines by eradication of recipient spermatogenesis using gamma-radiation. 2. A comparison between several radiation therapy treatments (based on 60Co isotope) of male testes was conducted using gamma-rays of 18, 22 and 26 Gy in a single dose or repeated doses of 5 x 8 Gy over a 15-d period. Sperm concentration and motility were determined after each treatment. 3. Altered spermatogenesis was observed after a single treatment dose of 18 Gy, while single doses of 26 Gy were followed by reduced sperm numbers (from 22 x 10(9) to 31 x 10(6) sperm/ml) within 60 to 100 d after treatment. After a single treatment of 26 Gy sperm motility was reduced by 50%. In contrast, a fractionated treatment (5 x 8 Gy) with gamma-rays halted spermatogenesis 39 d after the distribution of the first 8 Gy dose. 4. Observations of the seminiferous tubules by electron microscopy performed 12 months after this treatment confirmed that moderate doses of gamma-rays (8 Gy) distributed repeatedly (5 x) over a limited period (15 d) sterilise adult fowl testes but maintain morphologically normal somatic (Leydig and Sertoli) cell populations.     

LATE COMPLICATIONS OF PELVIC IRRADIATION IN 16 DOGS

When external beam radiation therapy is administered to the pelvis, normal tissues irradiated may include the colon, small intestine, urethra, bladder, bone, and spinal cord. The objectives of this retrospective study were to determine the incidence and severity of late radiation effects following pelvic irradiation in dogs and to identify factors that increase the risk of these effects. Medical records of all dogs treated with curative intent external beam radiation therapy to the pelvic region between 1993 and 1999 were reviewed. Patients with follow-up longer than 9 months or any patient that developed late complications earlier than 9 months were evaluated. Sixteen dogs met criteria for inclusion in this study. All dogs were treated with a 6-MV linear accelerator with bilaterally opposed beams. Diseases treated included transitional cell carcinoma of the bladder, transitional cell carcinoma of the prostate, and anal sac apocrine gland adenocarcinoma. Four dose/fractionation schemes were used: 49.5 Gy in 3.3 Gy fractions, 54 Gy in 3.0 Gy fractions, 54 Gy in 2.7 Gy fractions, and 18 Gy intraoperative radiation therapy followed by 43 Gy external beam radiation therapy in 2.9 Gy fractions. Implantable chemotherapy in the form of an OPLA-Pt sponge was used in six dogs as a radiation potentiator. Colitis was the major late effect following pelvic irradiation, occurring in nine dogs (56%). Colitis was characterized as mild in three dogs, moderate in one dog, and severe in five dogs. Three of the dogs with severe effects suffered gastrointestinal perforation. All dogs with severe late effects received 3 or 3.3 Gy per fraction, and 80% received radiation potentiators. In the seven dogs that received 2.7 Gy or 2.9 Gy per fraction, late effects were classified as none (n = 5), mild colitis (n = 1), and moderate colitis (n = 1). Radiation therapy can be administered to the pelvic region with a minimal risk of late effects to the colon by giving smaller doses per fraction and avoiding systemic radiation potentiators.     

Radiation therapy in two cats with pituitary tumors

Two cats with large pituitary neoplasms (adenoma and adenocarcinoma) were treated with fractionated radiation therapy. Total doses of 40 Gy, respectively 36 Gy, were applied in 10 fractions of 4 Gy, and 3.6 Gy respectively. Side effects were minimal and transient. Anesthesia was well tolerated. Improvement of clinical signs could be observed during radiation therapy in both cats. One cat had a complete, the other a partial tumor response. One cat (suspicion of adenoma) was euthanized 1 3/4 years after therapy due to unrelated disease. No tumor was found on histopathology, however a small focal necrosis of brain tissue in the irradiated field was observed. The second animal with a pituitary adenocarcinoma was euthanized because of tumor recurrence 1 1/2 years after therapy. Radiation therapy was effective, despite the low total doses of radiation applied.     

Intrinsic radiosensitivity and repair of sublethal radiation-induced damage in canine osteosarcoma cell lines

OBJECTIVE: To characterize the radiosensitivity and capacity for sublethal damage repair (SLDR) of radiation-induced injury in 4 canine osteosarcoma cell lines. SAMPLE POPULATION: 4 canine osteosarcoma cell lines (HMPOS, POS, COS 31, and D17). PROCEDURES: A clonogenic colony-forming assay was used to evaluate the cell lines' intrinsic radiosensitivities and SLDR capacities. Dose-response curves for the cell lines were generated by fitting the surviving fractions after radiation doses of 0 (control cells), 1, 2, 3, 6, and 9 Gy to a linear quadratic model. To evaluate SLDR, cell lines were exposed to 2 doses of 3 Gy (split-dose experiments) at an interval of 0 (single 6-Gy dose), 2, 4, 6, or 24 hours, after which the surviving fractions were assessed. RESULTS: Mean surviving fraction did not differ significantly among the 4 cell lines at the radiation doses tested. Mean surviving fraction at 2 Gy was high (0.62), and the alpha/beta ratios (predictor of tissue sensitivity to radiation therapy) for the cell lines were low (mean ratio, 3.47). The split-dose experiments revealed a 2.8- to 3.9-fold increase in cell survival when the radiation doses were applied at an interval of 24 hours, compared with cell survival after radiation doses were applied consecutively (0-hour interval). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that these canine osteosarcoma cell lines are fairly radioresistant; alpha/beta ratios were similar to those of nonneoplastic, late-responding tissues. Future clinical investigations should involve increasing the fraction size in a manner that maximizes tumor killing without adverse effects on the nonneoplastic surrounding tissues.     

~(60)Co-γ射线辐射鹅观草诱变效应研究初报

用不同剂量10、20、30、40、50 Gy60Co-γ射线辐射直穗鹅观草与垂穗鹅观草干种子,研究了两种鹅观草的适宜诱变剂量及辐射后其生物学性状的变异。结果表明:60Co-γ射线辐射对垂穗鹅观草的出苗率产生了促进作用,促进2种鹅观草出苗的最佳辐射剂量是40 Gy。两种鹅观草在10、20、30、40Gy辐射处理时,分蘖数均高于对照,50 Gy辐射处理抑制了鹅观草分蘖6。0Co-γ射线处理后直穗鹅观草株高均高于对照,而垂穗鹅观草的株高均低于对照。辐射处理抑制了直穗鹅观草的结穗能力。两种鹅观草穗长和平均小穗数与辐射剂量的相关性很高,均随着辐射剂量的增大而增大。初步确定促进鹅观草生物学性状变异的适宜辐射剂量为30~40 Gy。     

Higher sensitivity in induction of apoptosis in fibroblast cell lines derived from LEC strain rats to ultraviolet B radiation

When lung fibroblast cell lines from LEC and WKAH rats were irradiated with ultraviolet B (UVB) and assayed for colony formation, LEC rat cells showed a higher sensitivity than did WKAH rat cells. The LEC rat cells were approximately 1.5-fold more sensitive to UVB radiation than were the WKAH rat cells in terms of D37 values, which are the doses of UVB required to reduce cell survival to 37%. When the rat cells were irradiated with UVB in the presence of 0.5 M dimethyl sulfoxide (DMSO), which efficiently scavenges free radicals such as hydroxyl radicals, no significant difference was observed between the survival curves of either LEC or WKAH rat cells irradiated with UVB in the presence of 0.5 M DMSO and those irradiated with UVB in the absence of DMSO. Therefore, formation of free radicals may not be involved in cell death induced by UVB radiation. Flow cytometry showed that the percentage of apoptotic cells in the LEC rat cell population increased with post-incubation time after UVB radiation. The proportion of apoptotic cells in the UVB-irradiated LEC rat cell population increased as the dose of UVB was increased. In contrast, no significant proportion of apoptotic cells was observed in the UVB-irradiated WKAH rat cell population. These results showed a higher sensitivity in induction of apoptosis by UVB radiation in LEC rat cells than in WKAH rat cells.     

Effect of immunization on the quantitative behavior of gamma globulins in the blood serum of cattle following whole-body x-ray irradiation

Five experiment series were applied to 38 calves, aged between two-and-a-half and four months, using whole-body exposure to X-ray treatment based on median lethal doses (MLD) between 1.2 Gy and 1.7 Gy. Various methods of immunisation were simultaneously applied, and their effects on irradiation-caused response of gamma globulin concentrations in blood serum were studied. Gamma globulin levels were determined by Kunkel's zinc sulphate turbidity test. Immunisation applied between 14 and 21 days prior to irradiation resulted on obvious stimulation of gamma globulin production. In two experiments with parenteral antigen application, gamma globulin levels increased through about 14 days in apparently irradiated animals declined, after that period of time, but they continued to rise in really irradiated probands. A high lethal dose of 1.7 Gy, however, was followed by significant drop, three weeks after irradiation, that is in concomitance with the climax of the radiation syndrome. When 1.5 Gy were used, rise in gamma globulin concentration was recordable also following oral administration of antigen. Response of irradiated animals was even more clearly pronounced by secondary reaction of antibody formation, following booster action due to experimental infection with homologous germs. The stimulating effect of irradiation upon gamma globulin levels in blood serum, when oral or parenteral immunisation had taken place, prior to irradiation, has been attributed to reaction of the immune-globulin producing system to the release of tissue proteins or tissue antigens. Immunisation, prior to irradiation, stimulated the immunological system which underwent stronger regeneration, after irradiation, or had obviously acquired higher resistance to radiation.     

Orthovoltage radiation and weekly low dose of doxorubicin for the treatment of incompletely excised soft-tissue sarcomas in 39 dogs

The efficacy and toxicity of orthovoltage radiation therapy and concurrent low doses of doxorubicin for the treatment of incompletely excised soft-tissue sarcomas in 39 dogs was investigated retrospectively. The 39 dogs had 40 soft-tissue sarcomas and received 51 Gy orthovoltage radiation in 17 daily 3 Gy fractions; they also received 10 mg/m(2) doxorubicin once a week administered intravenously one hour before the dose of radiation. The median follow-up time was 910 days. The tumours recurred locally in seven of the dogs, in five of them within the radiation field; the median time to their recurrence was 213 days (range 63 to 555 days). Six of the dogs developed a distant metastasis after a median time of 276 days (range eight to 826 days). The one-year and two- to four-year tumour control rates were 84 per cent and 81 per cent, respectively, and the one-, two- and three- to four-year survival rates were 85 per cent, 79 per cent and 72 per cent, respectively. Tumours with a mitotic rate of more than 9 per 10 high-power fields were significantly more likely to recur, and the dogs with such tumours survived for significantly shorter periods.     

不同剂量中波紫外线照射对鹌鹑内脏器官重量的影响

将10日龄鹌鹑300只(公、母各半)随机分成5组,每组60只(公、母各30只),以功率为15 W的中波紫外灯为紫外线光源,以每天连续照射1 h、2 h、4 h和6 h(紫外线照射剂量分别为1.4μW.h/cm2、2.8μW.h/cm2、5.6μW.h/cm2和8.4μW.h/cm2)的鹌鹑为试验组,未接受紫外线照射的鹌鹑为对照组,试验期为4周。系统比较了不同紫外线照射剂量下鹌鹑心脏、肝脏、脾脏、肺脏、肾脏、肌胃和腺胃等各内脏器官的重量。结果表明:每天照射1 h的中波紫外线(照射剂量为1.4μW.h/cm2)可显著增加心脏和肝脏的重量。     

A BOOST TECHNIQUE FOR IRRADIATION OF MALIGNANT CANINE NASAL TUMORS

Eighteen dogs with malignant nasal cavity tumors were treated with radiation therapy, including a boost technique. Three 3:0 Gy boost doses were added to a treatment protocol consisting of sixteen 3.0 Gy daily fractions, bringing the total dose to 57 Gy. This boost technique was implemented without an associated increase in overall treatment time by giving the boost doses on a twice-a-day basis. Boost doses were given during the first half of the radiation therapy period. The treatment was completed as planned in 16 of the 18 dogs; two dogs received lower doses (51 and 54 Gy). Median survival was 177 days, poorer than in some other reported studies of nasal tumor irradiation. Acute effects were unacceptable, with 11 of the 18 dogs developing severe mucositis, desquamation, edema, swelling, and pruritus. The extensive nature of the acute reactions compromised assessment of the effect of the increased radiation dose on the tumor. Although there is justification for assessing more aggressive radiation protocols in canine nasal tumor patients, total doses approximating 60 Gy can not be given as described because of the inability of acutely responding normal tissues to compensate.     

X-irradiation Removes Endogenous Primordial Germ Cells (PGCs) and Increases Germline Transmission of Donor PGCs in Chimeric Chickens

Primordial germ cells (PGCs) are embryonic precursors of germline cells with potential applications in genetic conservation, transgenic animal production and germline stem cell research. These lines of research would benefit from improved germline transmission of transplanted PGCs in chimeric chickens. We therefore evaluated the effects of pretransplant X-irradiation of recipient embryos on the efficacy of germline transmission of donor PGCs in chimeric chickens. Intact chicken eggs were exposed to X-ray doses of 3, 6 and 9 Gy (dose rate = 0.12 Gy/min) after 52 h of incubation. There was no significant difference in hatching rate between the 3-Gy-irradiated group and the nonirradiated control group (40.0 vs. 69.6%), but the hatching rate in the 6-Gy-irradiated group (28.6%) was significantly lower than in the control group (P<0.05). No embryos irradiated with 9 Gy of X-rays survived to hatching. X-irradiation significantly reduced the number of endogenous PGCs in the embryonic gonads at stage 27 in a dose-dependent manner compared with nonirradiated controls. The numbers of endogenous PGCs in the 3-, 6- and 9-Gy-irradiated groups were 21.0, 9.6 and 4.6% of the nonirradiated control numbers, respectively. Sets of 100 donor PGCs were subsequently transferred intravascularly into embryos irradiated with 3 Gy X-rays and nonirradiated control embryos. Genetic cross-test analysis revealed that the germline transmission rate in the 3-Gy-irradiated group was significantly higher than in the control group (27.5 vs. 5.6%; P<0.05). In conclusion, X-irradiation reduced the number of endogenous PGCs and increased the germline transmission of transferred PGCs in chimeric chickens.     

Inhibition of Crandell-Rees Feline Kidney cell proliferation by X-ray-induced senescence

Radioresistance and radiotoxicity have been reported following cancer treatments in felines. Optimizing radiation doses to induce cytotoxic effects to only cancer cells and not normal cells is critical in achieving effective radiation therapy; however, the mechanisms of radiation resistance, radiotoxicity, and DNA damage response (DDR) in feline cells have not yet been elucidated. A DNA double-strand break (DSB) is the most toxic type of DNA damage induced by X-rays and heavy ion beams used in treating cancers. Crandell-Rees Feline Kidney (CRFK) cells is one of the most widely used cat cells in life science research. Here, we report that DSB-triggered senescence induced by X-rays is important in inhibiting the proliferation of CRFK cells. We demonstrated through cell proliferation assay that X-rays at doses 2 Gy and 10 Gy are toxic to CRFK cells that irradiating CRFK cells inhibits their proliferation. In X-irradiated CRFK cells, a dose-dependent increase in DSB-triggered senescence was detected according to morphological changes and using senescence-associated β galactosidase staining assay. Moreover, our data indicated that in CRFK cells, the major DDR pathway, which involves the phosphorylation of H2AX at Ser139, was normally activated by ATM kinases. Our findings are useful in the understanding of X-rays-induced cellular senescence and in elucidating biological effects of radiation, e.g., toxicity, in feline cells. Furthermore, our findings suggest that the CRFK cell line is an excellent matrix for elucidating radioresistance and radiotoxicity in cat cells.     

The effects of gamma irradiation on the lymphoid organs of rainbow trout and subsequent susceptibility to fish pathogens

Fish were irradiated with 60Co gamma rays at doses ranging from 10 to 50 Gy. Lethal doses were determined in fishes of different ages. For a given dose, fry and fingerlings were more susceptible than subadults. Whatever the irradiation dose was, the fish displayed a sharp decrease in blood leucocyte count. At the lowest doses, this acute leucopaenia was reversible. The cellular damage in the lymphoid organs was particularly obvious in the thymus. The depletion of lymphoid cells from immunocompetent organs decreased (viral hemorrhagic septicaemia, VHS) or increased (Y. ruckeri, A salmonicida) the susceptibility of trout to pathogens. The suppressive effect of radiation was age dependent. Irradiation appeared to be a reliable technique to detect asymptomatic carrier fish.