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At least 685 records · Page 38Linked to original sources
PubMed1955

The effect of ionizing radiation on phagocytosis and the bactericidal power of the blood. I. The effect of radiation on migration of leucocytes.

Exposure of rats to 600 r total body radiation did not influence either the rate or the extent of migration of their leucocytes 1 day after irradiation, but did decrease their migration on the 2nd and the 5th postirradiation day. Migration of rat leucocytes was not altered by infection of the animal with M. aureus. Leucocytes of rabbits irradiated with 100 r showed a normal rate and extent of migration. However rabbits exposed to 500 r or 800 r showed depression of leucocyte migration at two postirradiation intervals, on the 3rd to 5th and the 10th to 13th days after irradiation, with normal activity intervening. By the 21st postirradiation day the ability of leucocytes to migrate returned to normal. The effect of radiation on total and differential W.B.C. counts and the relationship of this effect to migration is discussed. The decrease in leucocyte migration could not be ascribed either to leucopenia or to plasma factors.

Animals↗
PubMed1960

Studies on susceptibility to infection following ionizing radiation. V. Comparison of intraperitoneal and intravenous challenge at intervals following different doses of x-radiation.

Ten week old female CF-1 mice were subjected to a single total body exposure of x-radiation in one of the following doses: 300, 400, and 500 r. At intervals thereafter, susceptibility to bacterial infection was determined by intraperitoneal challenge with graded inocula of Pseudomonas aeruginosa. Mice exposed to 400 or 500 r were also challenged by intravenous inoculation. The LD(50) of the test microorganism in each challenge was estimated from the mortality data. Exposure to 300 r caused little increase in susceptibility to this experimental infection. 400 r caused a moderate increase on the 3rd day post-irradiation with return to normal on the 17th. Leucocyte counts (geometric means) following this dose of radiation did not fall below 1200. 500 r caused a marked increase in susceptibility which lasted from the 3rd to 11th day, during which period the leucocyte counts were below 800. On the 20th day, susceptibility to infection was normal, although the geometric mean of leucocyte counts was only 2200. Comparison of mortalities resulting from equivalent inocula introduced by the two routes (intravenous and intraperitoneal) showed no difference in unirradiated mice. However, among mice irradiated with 400 or 500 r, higher mortalities resulted from intravenous inoculation. The difference was found to be due to the establishment of a small focus of infection at the site of intravenous injection as a result of leakage of a minute fraction of inoculum into the perivenous tissues of the tail. Bacterial multiplication occurred in such foci in irradiated (leucopenic) mice, but not in unirradiated mice, nor at the site of intraperitoneal inoculation even in irradiated mice.

Animals↗
PubMed2005

Radiation damage to the heart enhances early radiation-induced lung function loss.

In many thoracic cancers, the radiation dose that can safely be delivered to the target volume is limited by the tolerance dose of the surrounding lung tissue. It has been hypothesized that irradiation of the heart may be an additional risk factor for the development of early radiation-induced lung morbidity. In the current study, the dependence of lung tolerance dose on heart irradiation is determined. Fifty percent of the rat lungs were irradiated either including or excluding the heart. Proton beams were used to allow very accurate and conformal dose delivery. Lung function toxicity was scored using a breathing rate assay. We confirmed that the tolerance dose for early lung function damage depends not only on the lung region that is irradiated but also that concomitant irradiation of the heart severely reduces the tolerance of the lung. This study for the first time shows that the response of an organ to irradiation does not necessarily depend on the dose distribution in that organ alone.

Animals↗
PubMed2005

Randomized trial of amifostine in locally advanced non-small-cell lung cancer patients receiving chemotherapy and hyperfractionated radiation: radiation therapy oncology group trial 98-01.

PURPOSE: To test the ability of the cytoprotectant, amifostine, to reduce chemoradiotherapy-induced esophagitis and evaluate its influence on quality of life (QOL) and swallowing symptoms. PATIENTS AND METHODS: A total of 243 patients with stage II to IIIA/B non-small-cell lung cancer received induction paclitaxel 225 mg/m(2) intravenously (IV) days 1 and 22 and carboplatin area under the curve (AUC) days 1 and 22, followed by concurrent weekly paclitaxel (50 mg/m(2) IV) and carboplatin (AUC 2), and hyperfractionated radiation therapy (69.6 Gy at 1.2 Gy bid). Patients were randomly assigned at registration to amifostine (AM) 500 mg IV four times per week or no AM during chemoradiotherapy. Beyond standard toxicity end points, physician dysphagia logs (PDLs), daily patient swallowing diaries, and QOL (EORTC QLQ-C30/LC-13) were also collected. Swallowing AUC analyses were calculated from patient diaries and PDLs. RESULTS: A total of 120 patients were randomly assigned to receive AM, and 122, to receive no AM (one patient was ineligible); 72% received AM per protocol or with a minor deviation. AM was associated with higher rates of acute nausea (P = .03), vomiting (P = .007), cardiovascular toxicity (P = .0001), and infection or febrile neutropenia (P = .03). The rate of >/= grade 3 esophagitis was 30% with AM versus 34% without AM (P = .9). Patient diaries demonstrated lower swallowing dysfunction AUC with amifostine (z test P = .025). QOL was not significantly different between the two arms, except for pain, which showed more clinically meaningful improvement and less deterioration at 6 weeks follow-up (v pretreatment) in the AM arm (P = .003). The median survival rates for both arms were comparable (AM, 17.3 v no AM, 17.9 months; P = .87). CONCLUSION: AM did not significantly reduce esophagitis >/= grade 3 in patients receiving hyperfractionated radiation and chemotherapy. However, patient self-assessments suggested a possible advantage to AM that is being explored with modified dosing route strategies.

Aged↗
PubMed2005

Dose-dependent misrejoining of radiation-induced DNA double-strand breaks in human fibroblasts: experimental and theoretical study for high- and low-LET radiation.

Misrejoining of DNA double-strand breaks (DSBs) was measured in human primary fibroblasts after exposure to X rays and high-LET particles (helium, nitrogen and iron) in the dose range 10-80 Gy. To measure joining of wrong DNA ends, the integrity of a 3.2-Mbp restriction fragment was analyzed directly after exposure and after 16 h of repair incubation. It was found that the misrejoining frequency for X rays was nonlinearly related to dose, with less probability of misrejoining at low doses than at high doses. The dose dependence for the high-LET particles, on the other hand, was closer to being linear, with misrejoining frequencies higher than for X rays, particularly at the lower doses. These experimental results were simulated with a Monte Carlo approach that includes a cell nucleus model with all 46 chromosomes present, combined with realistic track structure simulations to calculate the geometrical positions of all DSBs induced for each dose. The model assumes that the main determinant for misrejoining probability is the distance between two simultaneously present DSBs. With a Gaussian interaction probability function with distance, it was found that the data for both low- and high-LET radiation could be fitted with an interaction distance (sigma of the Gaussian curve) of 0.25 microm. This is half the distance previously found to best fit chromosomal aberration data in human lymphocytes using the same methods (Holley et al., Radiat. Res. 158, 568-580, 2002). The discrepancy may indicate inadequacies in the chromosome model, for example insufficient chromosomal overlap, but may also be partly due to differences between fibroblasts and lymphocytes.

Cells, Cultured↗
PubMed1988

Radiation injury in a patient with unusually high sensitivity to radiation.

Radiation therapy is usually given with the assumption that interindividual variations in radiosensitivity are small, except for some patients with hereditary diseases associated with increased sensitivity. Recently, we observed radiation induced pericarditis in a breast carcinoma patient, in whom clinical signs, blood counts and chromosome analysis after in vitro irradiation of blood suggested a state of unusually high radiosensitivity. No evidence of constitutional chromosome abnormality was found in karyotypic analysis with the G-banding technique.

Breast Neoplasms↗
PubMed2001

[Levels of radiation exposure and radiation risk in flights aboard the orbital complex "Mir" and the International space station].

The paper presents results of calculating mean daily values of absorbed and equivalent doses from galactic cosmic rays (GCR) and Earth's radiation belts (ERB) to crew members on orbital missions aboard Mir and the International space station during solar minimum and maximum. Calculated doses were corrected in accordance with the dosimetric and spectrometric data from Mir missions 18 through to 23 that took place in the period of solar minimum. Contribution of local and albedo neutrons to equivalent dose was also taken into account. Presented are calculated total radiation risk and tumor risk over life time for Mir and ISS crews following missions of varying duration, and predictions for reduction in life span in view of recent dosimetric data.

Adult↗
PubMedDate not supplied

[Adaptation processes in natural Drosophila populations in radiation contaminated Belarus regions before and after radiation exposure removal].

We have shown that natural drosophila populations from the settlement Vetka of Gomel region with increased radiation background are more adapted to mutagenic effect of radiation than drosophila populations from Berezinsky reserve (the control). After the populations were placed into laboratory thermostat adaptation of Vetka population remained within 6-8 generations without irradiation. However the control population became more resistant too. So, the keeping of natural drosophila populations under laboratory conditions was a stress and led to unspecific adaptation the same as a low level of radiocontamination did. These facts should be considered in studying dynamics of the mutation level during radionuclide removal in animals caught in radiocontaminated regions and placed in vivaria conditions.

Adaptation, Physiological↗
PubMedDate not supplied

[The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 1. The experimental model. The radiation loads on animals kept continuously under external and internal radiation exposure in the area of the Chernobyl Atomic Electric Power Station].

Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.

Accidents↗
PubMed1991

[The regulations of radiation exposure, radiation loads on the population and the medical consequences of the Chernobyl accident].

The paper is concerned with analysis of strategy of the regulation of radiation exposure of the population and the practical use of the levels of intervention in different phases after the Chernobyl accident. The author represents data on the levels of whole-body irradiation of the population in the areas under strict control, and dose exposure of the thyroid in children and adults. Mean individual and collective doses of whole-body irradiation over the period of 1986-1989 and predictable dose exposures were assessed. Some data on probable pathology of radiation genesis in the population in affect on 1990 were considered.

Accidents↗
PubMed1989

[Biophysical foundations of the effect of cosmic radiation and accelerator radiation].

This book summaries the results of numerous studies, mainly by Soviet investigators, of the characteristics of radiation effects of high energy cosmic rays and of their simulation by heavy charged particle accelerators, and also of their biological effects. It contains the first systematic presentation of data on specific hadron effects. Facts are given showing the ability of these particles to cause profound local damage in tissues and organs. There is evidence that these particles should be considered one of the main factors limiting the duration of space flights. In the book a generalized kinetic model of radiation-induced cellular damage also is presented. This model allows an explanations of the observed changes in dose related survival with increasing LET and dose-rate, based on microdosimetric conceptions.

Animals↗
PubMed1980

Pathology of experimental radiation pancarditis. I. Observation on radiation-induced heart injuries following a single dose of x-ray irradiation to rabbit heart with special reference to its pathogenesis.

Radiation-induced heart injuries were morphologically studied by using the rabbits irradiated with a single dose of 3,000R (group I) or 300R of X-ray group II) from 1 hour until 6 months. There was no essential difference in the lesions of the hearts from group I and that of group II. Acute epicarditis was found as early as 1 hour after irradiation and it became maximum in severity at 1-2 days. In the myocardium, there were degeneration and resolution of the myocardial cell, various architectural changes of mitochondria, and disorganization of the intercalated disc. Polymorphonuclear cell infiltration and endothelial injuries of the capillaries occurred in the interstitial tissue. In addition, endocarditis with or without thrombus formation was often found. Acute inflammation was seen in the myocardium of group II rather later than that of group I, but it disappeared earlier. In the later stage, fibrosis finally occurred in the epicardium and endocardium. Glycoprotein degeneration of the muscle cells and fibrosis appeared in the myocardium. The pathogenesis of radiation pancarditis is thought to be dependent not only on the disturbance of microcirculation caused by endothelial cell damage of the capillaries, but also on alterations of the myocardial mitochondria as a result of direct injury.

Animals↗
PubMed1998

Biochemical outcome after radical prostatectomy, external beam radiation therapy, or interstitial radiation therapy for clinically localized prostate cancer.

CONTEXT: Interstitial radiation (implant) therapy is used to treat clinically localized adenocarcinoma of the prostate, but how it compares with other treatments is not known. OBJECTIVE: To estimate control of prostate-specific antigen (PSA) after radical prostatectomy (RP), external beam radiation (RT), or implant with or without neoadjuvant androgen deprivation therapy in patients with clinically localized prostate cancer. DESIGN: Retrospective cohort study of outcome data compared using Cox regression multivariable analyses. SETTING AND PATIENTS: A total of 1872 men treated between January 1989 and October 1997 with an RP (n = 888) or implant with or without neoadjuvant androgen deprivation therapy (n = 218) at the Hospital of the University of Pennsylvania, Philadelphia, or RT (n = 766) at the Joint Center for Radiation Therapy, Boston, Mass, were enrolled. MAIN OUTCOME MEASURE: Actuarial freedom from PSA failure (defined as PSA outcome). RESULTS: The relative risk (RR) of PSA failure in low-risk patients (stage T1c, T2a and PSA level < or =10 ng/mL and Gleason score < or =6) treated using RT, implant plus androgen deprivation therapy, or implant therapy was 1.1 (95% confidence interval [CI], 0.5-2.7), 0.5 (95% CI, 0.1-1.9), and 1.1 (95% CI, 0.3-3.6), respectively, compared with those patients treated with RP. The RRs of PSA failure in the intermediate-risk patients (stage T2b or Gleason score of 7 or PSA level >10 and < or =20 ng/mL) and high-risk patients (stage T2c or PSA level >20 ng/mL or Gleason score > or =8) treated with implant compared with RP were 3.1 (95% CI, 1.5-6.1) and 3.0 (95% CI, 1.8-5.0), respectively. The addition of androgen deprivation to implant therapy did not improve PSA outcome in high-risk patients but resulted in a PSA outcome that was not statistically different compared with the results obtained using RP or RT in intermediate-risk patients. These results were unchanged when patients were stratified using the traditional rankings of biopsy Gleason scores of 2 through 4 vs 5 through 6 vs 7 vs 8 through 10. CONCLUSIONS: Low-risk patients had estimates of 5-year PSA outcome after treatment with RP, RT, or implant with or without neoadjuvant androgen deprivation that were not statistically different, whereas intermediate- and high-risk patients treated with RP or RT did better then those treated by implant. Prospective randomized trials are needed to verify these findings.

Adenocarcinoma↗
PubMed1980

Value of radiation therapy in the management of patients with cerebral metastases from malignant melanoma: Radiation Therapy Oncology Group Brain Metastases Study I and II.

Sixty patients from two Radiation Therapy Oncology Group (RTOG) studies with cerebral metastases from malignant melanoma were analyzed to determine the response to whole brain irradiation. General performance status, neurologic function, and specific neurologic symptoms were evaluated for rate and duration of improvement. Also analyzed was the influence of chemotherapy and steroids, although neither was a controlled factor. Results indicate a significant benefit from radiation therapy in terms of symptomatic and neurologic function improvement. Symptomatic improvement was observed in 76%, with 31% completely improved. Of the four most frequent symptoms, complete or partial improvement was observed as follows: headache--27 of 37 patients (73%); motor loss--14 of 23 patients (61%); impaired mentation--13 of 24 patients (62%); and convulsions--10 of 12 patients (83%). Improvement in neurologic function class was observed in 18 of 44 patients (41%). Median survival for Study 1 patients was 10 weeks (range 1-200) and that of Study II patients 14 weeks (range 1-76). These results are comparable to those found in radiation therapy of brain metastases from all other primary tumors.

Adrenal Cortex Hormones↗
PubMed1979

Randomized study of control of the primary tumor and survival using preoperative radiation, radiation alone, or surgery alone in head and neck carcinomas.

Fifty-five selected patients with previously untreated squamous cell carcinoma of the head and neck regions were studied in a randomized, prospective manner. The three treatment categories were primary radiation (Gp R), primary surgery (Gp S), and preoperative radiation of 4000 rads in four weeks (Gp R/S). The local control rates for the 44 evaluable patients with a two-year minimum followup were 24%, 39%, and 43% respectively. Further treatment attempts in patients failing initial therapy yielded local control rates of 35%, 39%, and 43% for Gp R, Gp S, and Gp R/S, respectively. None of the local control rates nor the corresponding survival curves were significantly different at P less than 0.10. However, the group sizes were sufficiently small that true differences might not have been detected. Postoperative complications were higher in the primary radiation failures subsequently operated upon compared to the primary surgery group (P = 0.07).

Carcinoma, Squamous Cell↗
PubMed1995

Plastic hollow waveguides: properties and possibilities as a flexible radiation delivery system for CO2-laser radiation.

BACKGROUND AND OBJECTIVES: One significant inconvenience of the CO2 laser is the lack of flexible fibers essential for endoscopic applications. The goal of this study is to test the feasibility of hollow waveguides in view of a practical use in medicine. STUDY DESIGN/MATERIALS AND METHODS: Various types of plastic hollow waveguides for flexible delivery of CO2 laser radiation were examined. The transmission losses, divergence angle, damage threshold, and input and output beam profiles were determined. The interaction process between radiation transmitted through these guides with soft as well as hard tissues was studied. RESULTS: Plastic hollow waveguides can transmit high power (up to 50 W) with low losses (straight guide 1 dB/m) even through bendings. The divergence angle is < 13 degrees. Cutting quality and extent of thermal damage are comparable to incisions performed with a free laser beam. CONCLUSION: The results of this study show good cutting quality and durability of these flexible plastic hollow waveguides, which render possible to deliver CO2 radiation in the power range needed for most surgical applications with affordable transmission losses. Plastic hollow waveguides are, therefore, a real alternative to replace the mirror arms.

Animals↗
PubMed1989

31P NMR spectroscopic study of bioenergetic changes in radiation-induced fibrosarcoma-1 after radiation therapy.

The effects of localized gamma-irradiation on the in vivo 31P NMR spectra of RIF-1 tumors grown subcutaneously in C3H/HeN mice have been examined before and during the week after treatment. Increases in the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) and in tumor pH, and decreases in the ratio of Pi to the beta phosphorus resonance of the nucleotide triphosphates (beta NTP) were observed in irradiated tumors. The time course of changes in the 31P spectrum following treatment was the opposite of the pattern during untreated growth, and the magnitude and duration of the changes increased with increasing radiation dose, decreasing clonogenic cell survival and increasing growth delay. To examine the possibility that nontherapeutic systemic effects of the tumor irradiation were responsible for the changes observed, a number of animals bearing two tumors were examined. One tumor on each mouse was selectively irradiated. Changes in tumor volume, Pi/beta NTP, PCr/Pi, the ratio of phosphomonoesters to beta NTP, and tumor pH were all significantly different in the treated compared to the untreated tumor on each animal, indicating that these changes in 31P NMR spectra were a response to radiation therapy and not a systemic response to radiation toxicity.

Animals↗
PubMed1991

On the reaction of adult Rhipicephalus evertsi mimeticus and Hyalomma truncatum to horizontally incidenting optical radiation of various wavelengths ranges and different irradiances and to optical radiation of a sun-simulating wavelength spectrum.

The valence of horizontally incidenting light/optical radiation for host-seeking-inclined ixodid ticks was investigated by exposing male and female adults of Rhipicephalus evertsi mimeticus and Hyalomma truncatum to narrow-band monochromatic radiation in the wavelength range of 300-801 nm at irradiances corresponding to an overcast to clear sunny day, a cloudy day and a full-moon night as well as to optical radiation of a sun-simulating wavelength spectrum of 190-2600 nm within a test chamber from which other stimuli were excluded. It was demonstrated that independent of sex, adult ticks of R. e. mimeticus and H. truncatum responded to a wide wavelength spectrum in the visible and UV range, even at irradiances corresponding to a full-moon night. Interspecific differences existed in the degree and extent of the response as well as in the spectral sensitivity. Ticks of H. truncatum consistently showed a faster and stronger response and reacted phototactically positively in higher percentages than adults of R. e. mimeticus. Independent of wavelength range and irradiance, predominantly only few R. e. mimeticus ticks were stimulated to positive phototaxis, whereas at least 33.3% (in most cases, 50%) and maximally greater than 80% of H. truncatum adults reacted phototactically positively. Spectral sensitivity maxima were demonstrated at the yellow and red light and at the UV-A waveband width for R. e. mimeticus and at the violet, blue, green and yellow light wavelength for H. truncatum. With decreasing irradiance, the spectral sensitivity shifted to the blue wavelength range.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗