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PubMed1989

Standards and calibration facilities of the Australian Radiation Laboratory for ionizing radiation beams.

The Australian Radiation Laboratory (ARL) maintains national standards of exposure and working standards of absorbed dose. Some of the exposure standards maintained by ARL have been compared recently with those of the Bureau International des Poids et Mesures (BIPM) for 100 to 250 kV x-rays and 60Co gamma rays. The absorbed dose standard for 60Co gamma rays is compared regularly with other standards through the International Atomic Energy Agency (IAEA) and World Health Organization (WHO). All results show good agreement. A range of calibration qualities is offered at ARL, extending from 10 kV x-rays to 60Co gamma rays. A system of regional facilities has been developed for radiation protection calibrations; each facility is supplied with a set of 137Cs sources and an ionization chamber and electrometer for use with x-rays. The system is now almost complete throughout Australia.

Australia↗
PubMedDate not supplied

[Viability of rat thymocytes as affected by radiation and combined radiation-heat damage].

A share of damaged (nonviable) cells of rat thymus was quantitatively estimated on days 1 and 3 following irradiation with doses of 1, 3 and 6 Gy and a combined treatment with radiation and heat. The percentage of nonviable thymocytes was higher after the combined treatment than after the effect of radiation alone delivered in equivalent doses.

Animals↗
PubMed1985

Evidence for similarities between radiation damage expressed by beta-araA and damage involved in the interaction effect observed after exposure of V79 cells to mixed neutrons and gamma radiation.

Plateau-phase V79 cells were exposed sequentially to fast neutrons and gamma rays. A dose-dependent reduction in the shoulder width of the gamma-ray survival curve was observed after preexposure of cells to neutrons. A similar effect was demonstrated on the neutron survival curve when cells were preirradiated with gamma rays. Treatment of cells with 150 microM beta-araA after either gamma or neutron irradiation reduced primarily the shoulder of the survival curve. When beta-araA was given to the cells after exposure to mixed radiation modalities, survival curves similar to those observed after exposure to a single radiation modality and treatment with beta-araA were obtained. The kinetics of loss of the interaction observed after exposure of cells to gamma rays following neutron irradiation was similar to the kinetics of loss of sensitivity to beta-araA (T1/2 = 1 h) measured by delaying drug administration after exposure to gamma rays. The results suggest that the PLD expressed by beta-araA is at least partly involved in the interactive effect observed after combined exposure of plateau-phase V79 cells to neutrons and gamma rays.

Animals↗
PubMed1980

[Radiation therapy of cervix cancer with special reference to radiation effects upon the intestine (author's transl)].

The evaluation of the therapeutical preference of succession in the treatment of the uterine cervix, the radiation therapy today presents a special importance. This is established upon two facts; that is, the age-distribution and the incidence of the inoperability of the cases (one patient in every three cases of the cervical cancer is over 60 years of age; nearly 60% of the cases are in an inoperable stage). Although in our department only partially or completely inoperable cases went through a radiation therapy, 757 ( = 47,7% out of 1586 cases) achieved to survive for more than five years. At a discussion concerning the intestinal complications which occur due to irradiation, it has been proved, that 18,6% show reversible reactions. The permanent reactions like recto-vaginal-fistula etc. were only seen in 2,4%. It is interesting to note, that the patients subjected to intestinal complications were seen by advanced cases (stage III: 65,1%) and 69% of them were over 60 years of age. Irradiation consequences are by younger patients and by cases with a possible local operability rather rare. At the end, physiopathology and the treatment of the intestinal post-irradiation effects are discussed.

Age Factors↗
PubMed1980

Radiation sensitizing agents in clinical radiation and chemotherapy.

Patients with bronchogenic carcinoma or with advanced pediatric solid tumours were treated with various radiation therapy schedules alone or with a new alkylating carbamate: AB 132. Drug therapy appeared to potentiate radiation therapy results without significant toxicity except for certain neurologic symptoms (myasthenia, nightmares, disturbances of taste and smell). The latter appeared to be related to acetylcholinesterase and pseudocholinesterase inhibition.

Aziridines↗
PubMed1982

[Common proviral integration sites in C57BL mouse lymphoma induced by mouse radiation leukemia virus and absence of novel proviral sequences in DNA from radiation-induced lymphoma].

Radiation leukemia virus (RadLV)-induced lymphomas of C57BL mice display the appearance of novel proviral sequences at common sites of their DNAs. These results are compatible with the hypothesis of viral oncogenesis by promotor insertion. Radiation-induced tumors do not acquire detectable novel provirus, suggesting that activation of a transforming gene proceeds by a mechanism distinct from the former.

Animals↗
PubMed1984

[Multiple primary malignant cancer and radiation induced cancer--a point of view of radiation oncology].

The cases of multiple primary malignant neoplasm and radiation induced cancer were discussed based on the experiences of Tokyo Women's Medical College in which radiotherapy has been mainly used for cancer. These cases have been increasing in number and it seems to be that the problems of them shall be gradually developed in future, because survival time of cancer patients become longer due to improvement of cancer treatment. But if the mechanisms of cancer etiology on which radiation and other many things influence, would not be clear, radiotherapy have been still principal post in cancer treatment. Systemic multidisciplinary treatment of cancer must be considered and we are looking forward to establishing it.

Adult↗
PubMed1984

Effects of methoxsalen plus near-ultraviolet radiation or mid-ultraviolet radiation on immunologic mechanisms.

Skin cancers induced in mice by UVB, i.e., 280-320 nm radiation, are highly antigenic. They grow progressively in UVB-irradiated hosts because of certain specific immunologic alterations that are induced in the mice. Comparative studies of the immunologic aspects of carcinogenesis by UVB or methoxsalen plus UVA, i.e., 320-400 nm radiation (PUVA), formed the basis for the following conclusions: 1) Skin cancers induced by PUVA in C3H/HeN mammary tumor virus-negative mice are not highly antigenic, in contrast to those induced by UVB; 2) PUVA-induced tumors also differ from those induced by UVB, in that they do not exhibit preferential growth in UVB-irradiated mice; 3) PUVA treatment of mice, unlike UVB, does not induce susceptibility to the transplantation of UVB-induced tumors; 4) both UVB and PUVA treatments suppress the induction of contact hypersensitivity by a mechanism that involves suppressor lymphocytes.

Animals↗
PubMed1980

Absence of fractionation, protraction, radiation quality, and radical scavenger effects on radiation-induced interphase death of human G0 lymphocytes in vitro.

In vitro interphase death of human peripheral blood lymphocytes, measured by shortening of the mean lifetime of small G0 lymphocytes, was studied with 150 kV and 10 kV X-rays. No effect of radiation quality, of fractionation and of protraction was observed. The possibility of protection by L-cysteine and DMSO was tested in cells irradiated with 150 kV X-rays, but no protection effect with respect to cell survival could be demonstrated. Non-DNA radiation-sensitive site(s), possibly the cell membrane, appear to be responsible for interphase death.

Cell Membrane↗
PubMed1996

Radiation therapy: a radiation oncologist's point of view.

This article is intended as a clinical introduction to radiation therapy as a treatment modality. It discusses the indications and contraindications for radiotherapy. Additionally, it attempts to cover the expected response of a wide variety of tumors to radiation. It should be remembered that veterinary radiotherapy is still in its infancy, and that much of the information presented in this article is, unfortunately, anecdotal in nature.

Animals↗
PubMed1997

[A case of post-radiation constrictive pericarditis developing 12 years after radiation therapy].

A 70-year-old woman underwent radical mastectomy for carcinoma of the left breast in 1982. Postoperative radiation therapy was given in a total dose of 50 Gy for parasternal and left subclavian nodes. Symptoms of heart failure such as exertional dyspnea, facial edema, and hepatomegaly manifested in 1992. Cardiac catheterization revealed marked elevation of mean right atrial pressure and right ventricular end-diastolic pressure. The pressure wave form of the right ventricle showed the so called "dip and plateau" feature. Pericardiectomy without using extracorporeal circulation was performed in 1994. Operative findings and pathological study results were compatible with radiation-induced constrictive pericarditis. She rapidly recovered from heart failure after this operation, and has done very well to date.

Aged↗
PubMed1976

[Radiation pneumonitis and radiation fibrosis following systemic irradiation of thoracic lymph nodes in Hodgkin's disease].

146 of 226 patients suffering from Hodgkin's disease were submitted to a high voltage therapy in the chest using the method of single fields. In order to be in a position to judge the appearance and the development of a modification of the pulmonary parenchyma induced by radiations, the authors evaluated the data of 69 patients who could be checked up in relatively small intervals during at least one year after the radiotherapy. Dilatations of interpleural and hilar lymphomas or pulmonary infiltrates have to be considered as one of the most important causes of atypical pneumonia and fibrosis induced by radiation. 12 patients out of 35 (i.e. 35,3%) with intrathoracic lymphomatosis granulomatosa presented atypical pneumonias which mostly were not very serious, and four patients (i.e. 11,8%) had fibroses. If the mediastine was irradiated systematically for the purpose of prophylaxis, no pulmonary reaction was observed that could be demonstrated by means of X-rays.

Adolescent↗
PubMed2006

Possible selection effects for radiation risk estimates in Japanese A-bomb survivors: reanalysis of acute radiation symptoms data.

An earlier analysis examined the possibility of bias in the Life Span Study (LSS) cohort by studying Japanese A-bomb survivors with bomb-related acute injuries and those without such injuries. The authors reported significantly higher radiation risks, both for cancers and non-cancers, among those survivors with acute injuries compared with those without. The risks were reported to be particularly large among survivors aged <10 or > or =55 years of age at the time of bombings. The aim of this paper is to examine these findings more closely using the LSS acute effects data. All the analyses were carried out using Poisson regression. Relative risk models were fitted with adjustment for sex and other factors. Significant differences in relative risk between survivors with epilation and burns and those without epilation and burns are found for leukaemia. There is also some evidence for heterogeneity in the leukaemia risk between survivors with two or more acute injuries and those with no injuries, but the evidence is disappeared when survivors with one or more injuries are compared with those without injuries. For solid cancers, cardiovascular disease and all deaths combined, the risks do not differ to a statistically significant extent between survivors with and without injuries. There is no statistically significant heterogeneity in risk across age-at-exposure categories for survivors with injuries. For all deaths combined, relative risk estimates and their uncertainties are significantly higher for survivors exposed at ages <10 years when compared with other exposure ages, but risks are not significantly raised for survivors exposed at > or =55 years of age. With the exception of leukaemia, the findings from the present work are inconsistent with those of Stewart and Kneale.

Adult↗
PubMed1952

Studies on the mechanism of action of ionizing radiations. VII. Cellular respiration, cell division, and ionizing radiations.

On x-irradiation of the eggs and sperm of Arbacia punctulata there was inhibition of respiration with relatively large doses, whereas there was an increase with small doses. The dose required to produce an increase of respiration depended on the degree of sensitivity of the cell to the effect of ionizing radiation. Sperm cells were more sensitive; then came fertilized eggs; unfertilized eggs were the least sensitive. The inhibiting effect of x-rays on cell division was observed even on irradiation with x-ray doses which produced an increase of respiration. These results are compared to similar effects produced by thiol reagents and are attributed to oxidation of the thiol compounds in the cell.

Cell Division↗
PubMed1975

Carcinogenic effect of radiation on the mouse embryo; physical aspects of radiation dosimetry.

The doses received by the embryos from abdominal irradiation of the females at the time of pregnancy may adversely affect the offspring. The dose to the embryo will depend on the depth of the embryo from the surface, the distance of the embryo from the central axis of the beam and on the photon energy. A knowledge of the dose as well as the percentage depth dose in this region will be necessary for the meaningful correlation between the radiation dose and the neoplasm formation due to prenatal irradiation. This paper presents the results of our experimental investigation of the percentage depth doses in a mouse phantom. The results of theoretical computation of percentage depth doses to off-axis points are found to be in good agreement with the experimental values.

Adenocarcinoma↗
PubMed2004

Apoptosis induced by ultraviolet radiation is enhanced by amplitude modulated radiofrequency radiation in mutant yeast cells.

The aim of this study was to investigate whether radiofrequency (RF) electromagnetic field (EMF) exposure affects cell death processes of yeast cells. Saccharomyces cerevisiae yeast cells of the strains KFy417 (wild-type) and KFy437 (cdc48-mutant) were exposed to 900 or 872 MHz RF fields, with or without exposure to ultraviolet (UV) radiation, and incubated simultaneously with elevated temperature (+37 degrees C) to induce apoptosis in the cdc48-mutated strain. The RF exposure was carried out in a special waveguide exposure chamber where the temperature of the cell cultures can be precisely controlled. Apoptosis was analyzed using the annexin V-FITC method utilizing flow cytometry. Amplitude modulated (217 pulses per second) RF exposure significantly enhanced UV induced apoptosis in cdc48-mutated cells, but no effect was observed in cells exposed to unmodulated fields at identical time-average specfic absorption rates (SAR, 0.4 or 3.0 W/kg). The findings suggest that amplitude modulated RF fields, together with known damaging agents, can affect the cell death process in mutated yeast cells. Bioelectromagnetics 25:127-133, 2004.

Apoptosis↗
PubMed2005

Evidence for beneficial low level radiation effects and radiation hormesis.

Low doses in the mGy range cause a dual effect on cellular DNA. One is a relatively low probability of DNA damage per energy deposition event and increases in proportion to the dose. At background exposures this damage to DNA is orders of magnitude lower than that from endogenous sources, such as reactive oxygen species. The other effect at comparable doses is adaptive protection against DNA damage from many, mainly endogenous, sources, depending on cell type, species and metabolism. Adaptive protection causes DNA damage prevention and repair and immune stimulation. It develops with a delay of hours, may last for days to months, decreases steadily at doses above about 100 mGy to 200 mGy and is not observed any more after acute exposures of more than about 500 mGy. Radiation-induced apoptosis and terminal cell differentiation also occur at higher doses and add to protection by reducing genomic instability and the number of mutated cells in tissues. At low doses reduction of damage from endogenous sources by adaptive protection maybe equal to or outweigh radiogenic damage induction. Thus, the linear-no-threshold (LNT) hypothesis for cancer risk is scientifically unfounded and appears to be invalid in favour of a threshold or hormesis. This is consistent with data both from animal studies and human epidemiological observations on low-dose induced cancer. The LNT hypothesis should be abandoned and be replaced by a hypothesis that is scientifically justified and causes less unreasonable fear and unnecessary expenditure.

Apoptosis↗
PubMed1976

[Radiation exposure and radiation protection in radiodiagnosis of the temporomandibular joint].

There are considerable differences in the various methods of taking x-rays of the temporo-mandibular joint as far as skin exposure to radiation is concerned. Our own measurements revealed doses ranging from 0.2 to 0.8 rem. The values were especially high when using the method of PARMA. Therefore the question is raised whether, considering the provisions of the radiology regulations, there are any cases in which this way to demonstrate the temporomandibular joint is still indicated. As to the measured gonadal doses ranging between 0.02 and 0.18 mrem, no essential differences in the indications of the various methods need to be considered.

Dose-Response Relationship, Radiation↗