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PubMedDate not supplied

Plant responses to current solar ultraviolet-B radiation and to supplemented solar ultraviolet-B radiation simulating ozone depletion: an experimental comparison.

Field experiments assessing UV-B effects on plants have been conducted using two contrasting techniques: supplementation of solar UV-B with radiation from fluorescent UV lamps and the exclusion of solar UV-B with filters. We compared these two approaches by growing lettuce and oat simultaneously under three conditions: UV-B exclusion, near-ambient UV-B (control) and UV-B supplementation (simulating a 30% ozone depletion). This permitted computation of "solar UV-B" and "supplemental UV-B" effects. Microclimate and photosynthetically active radiation were the same under the two treatments and the control. Excluding UV-B changed total UV-B radiation more than did supplementing UV-B, but the UV-B supplementation contained more "biologically effective" shortwave radiation. For oat, solar UV-B had a greater effect than supplemental UV-B on main shoot leaf area and main shoot mass, but supplemental UV-B had a greater effect on leaf and tiller number and UV-B-absorbing compounds. For lettuce, growth and stomatal density generally responded similarly to both solar UV-B and supplemented UV-B radiation, but UV-absorbing compounds responded more to supplemental UV-B, as in oat. Because of the marked spectral differences between the techniques, experiments using UV-B exclusion are most suited to assessing effects of present-day UV-B radiation, whereas UV-B supplementation experiments are most appropriate for addressing the ozone depletion issue.

Atmosphere↗

PubMed2002

Identification of radiation-responsive genes in vitro using a gene trap strategy predicts for modulation of expression by radiation in vivo.

A large number of genes are known to be responsive to ionizing radiation, and there is strong evidence for the existence of inducible radiation resistance in mammalian cells. We have developed a gene trap insertional mutagenesis strategy to identify novel genes involved in responses to radiation. Using this approach, we have isolated four gene-trap integrations in embryonic stem cells. In three cases (9A, 3E and 9H) the trapped genes are radiation-inducible, and in one (7D) the gene is down-regulated. Sequence analysis of fusion transcripts from three of the integrations indicate one novel gene (3E), the mouse homologue (9A) of a known but uncharacterized human gene that encodes a protein with significant homology to several GTPase-activating proteins and a murine locus, Mym (9H). The embryonic stem cell clone with the 9A insertion was introduced into the mouse germline, and the in vivo expression pattern of 9A was studied in detail. A unique, spatially restricted pattern of expression in embryos and adult animals was observed. There is tissue-specific in vivo induction of the 9A gene in adult mice by radiation. This study demonstrates the potential of the gene trap approach for the identification and functional analysis of novel radiation-regulated genes. Similar strategies may facilitate the discovery and characterization of genes involved in other cellular stress responses.

Amino Acid Sequence↗

PubMed2001

Treatment with a combination of doxorubicin, surgery, and radiation versus surgery and radiation alone for cats with vaccine-associated sarcomas: 25 cases (1995-2000).

OBJECTIVE: To compare use of doxorubicin, surgery, and radiation versus surgery and radiation alone for treatment of cats with vaccine-associated sarcoma. DESIGN: Retrospective study. ANIMALS: 25 cats with vaccine-associated sarcomas. PROCEDURE: Time to first recurrence and survival time were compared between the 2 treatment groups. The number of surgeries (1 or > 1) were compared with respect to time to first recurrence and survival time. RESULTS: Median time to first recurrence was 661 days for the group that received doxorubicin, surgery, and radiation. Median time to first recurrence has not yet been attained for the group treated with surgery and radiation alone. Median survival time was 674 days for the group treated with doxorubicin, surgery, and radiation and 842 days for the group treated with surgery and radiation alone. For time to first recurrence and survival time, significant differences were not detected between cats that had 1 surgery and those that had > 1 surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Significant differences between the 2 treatment groups were not detected. The efficacy of doxorubicin in the treatment of vaccine-associated sarcomas is uncertain.

Animals↗

PubMed1993

Surgical resection and radiation therapy versus biopsy and radiation therapy in the treatment of glioblastoma multiforme.

There has been considerable controversy over the concept of treating glioblastoma multiforme with cytoreductive surgery. Therefore, a retrospective study of cases treated between 1986 and 1991 was conducted to analyze and compare the results of stereotactic biopsy followed by radiation therapy performed in 58 patients with those of surgical resection plus radiation therapy in 57 patients. In both groups, conventionally fractionated radiation (1.7 to 2.0 Gy/day) was delivered, with a total dose of 50 to 60 Gy. Biopsy was performed only in patients with tumors judged to be inoperable. These patients carried a higher surgical risk and were in worse neurological condition than the patients in the resection group. The median survival time for the resection group was 39.5 weeks, as compared with 32 weeks for the biopsy group. This difference was not significant. The most important prognostic factor was the patient's age. The treatment variable biopsy versus resection did not reach prognostic relevance. In patients with midline shift who underwent biopsy, the Karnofsky Performance Scale score decreased in more patients during radiation therapy. The clinical status 6 weeks after surgery, however, showed no significant differences between the two groups. The comparable survival times for the two groups place doubt on the concept of treating glioblastoma multiforme with cytoreductive surgery. Presently, radiation therapy is the most effective treatment for patients with glioblastoma. There is no question that decompressive surgery followed by radiation therapy should be performed whenever necessary for sever space-occupying lesions and when it will not cause new neurological deficits.

Aged↗

PubMed2000

[Occurrence of BOOP outside radiation field after tangential radiation therapy for breast carcinoma].

We report three cases of bronchiolitis obliterans organizing pneumonia (BOOP) that occurred outside the radiation field after radiation therapy using tangential fields for breast carcinoma. All patients complained of a cough between 14 and 20 weeks after completion of radiation therapy. Fever also developed in two of the three. Chest radiography and computed tomography demonstrated peripheral alveolar opacities outside the radiation field on the same side as the radiation therapy. Laboratory data showed an increased level of C-reactive protein and an increased erythrocyte sedimentation rate. Bronchoalveolar lavage showed an elevated total cell count with a very high percentage of lymphocytes. Transbronchial lung biopsy revealed a histologic pattern consistent with BOOP. Treatment with corticosteroids resulted in rapid clinical improvement and complete resolution of the radiographic abnormalities. This pulmonary disorder appears to be induced by radiation, especially when a tangential field is employed for breast carcinoma, though the etiology has not been fully investigated. It is important to be aware of this type of pulmonary complication in patients given radiotherapy for breast carcinoma.

Breast Neoplasms↗

PubMedDate not supplied

[Effect of extremely low frequency electromagnetic radiation and ultra-violet radiation on aggregation of thymocytes and erythrocytes].

Electromagnetic radiation of superhigh frequencies (46.12 and 46.19 GHz, 0.3-1 mV/cm2) at an incident dose of about 12 kJ/m2 enhances the ability of isolated rabbit thymocytes for aggregation interaction with homologous erythrocytes. In the case of 46.19 GHz frequency, the stimulatory effect disappears as radiation dose in increased. A radiation of 46.12 GHz stimulates thymocytes also at high radiation doses. Superhigh-frequency radiation enhances the sensitivity of thymocytes to the damaging effect of UV radiation.

Animals↗

PubMed2000

Inverse association between age at the time of radiation exposure and extent of disease in cases of radiation-induced childhood thyroid carcinoma in Belarus.

BACKGROUND: Increased incidence of childhood thyroid carcinoma, particularly in the youngest children, has been reported from Belarus since the nuclear reactor accident at Chernobyl in 1986. The relation between disease severity and age at the time of the accident, not previously established in this cohort, was analyzed in this study. METHODS: The authors studied the association between disease severity, expressed by TNM classification, and age at radiation exposure in a cohort of 483 patients younger than 8 years at the time of the Chernobyl accident who have been diagnosed with differentiated thyroid carcinoma since 1986 at the Center for Thyroid Cancer in Minsk. The associations between age at radiation exposure and TNM categories were compared among 4 groups of patients who were ages <2, 2.1-4, 4.1-6, and 6.1-8 years at the time of the accident. Multivariate discriminant analysis was performed to examine the effects of age at the time of the accident, gender, histology, tumor stage, and N classification on the frequency of distant metastasis. RESULTS: Younger age at the time of the Chernobyl accident was associated with greater extrathyroidal tumor extension (P<0.01) and more lymph node involvement (P<0.0001) and tended to be associated with more distant metastases (P = 0.09). Compared with patients who were ages 6.1-8 years at the time of the accident, patients who were younger than 2 years had significantly more extrathyroidal tumor invasion (P = 0.004), lymph node involvement (P = 0.004), and distant metastases (P = 0.05). The age at diagnosis increased with older age at the time of radiation exposure (linear regression analysis; correlation coefficient = 0. 67; P<0.001). Multivariate analysis revealed that younger age at the time of the accident (P = 0.001) and advanced locoregional tumor extension (P<0.001) were the only powerful factors influencing the risk for distant metastasis of this malignancy. CONCLUSIONS: The severity of disease was associated inversely with age at the time of radiation exposure in these cases of radiation-induced childhood thyroid carcinoma.

Adolescent↗

PubMed1997

Increased MRP expression is associated with resistance to radiation, anthracyclines and etoposide in cells treated with fractionated gamma-radiation.

The failure of chemotherapy is often associated with the failure of radiotherapy in the treatment of cancer. To investigate this relationship, the CCRF-CEM (CEM) human T-cell leukaemia cell line was treated with fractionated gamma-radiation totalling 75 Gy (10 cycles of 1.5 Gy daily for 5 days). This produced the CEMRR subline which was 1.5-fold resistant to radiation compared with the parental CEM cells. The CEMRR subline was also resistant to daunorbicin, idarubicin and etoposide but not to paclitaxel, cis-platinum or chlorambucil. Treatment with 50 microM buthionine sulphoximine, an inhibitor of glutathione synthesis, reversed the daunorubicin resistance in the CEMRR subline. Multidrug resistance-associated protein (MRP) mRNA was 6-fold higher in the CEMRR subline than in the CEM cells, and there was no detectable expression of P-glycoprotein in either the CEM cells or the CEMRR subline. Treatment of the CEM cells with 2 Gy of gamma-radiation caused an increase in MRP-mRNA within 4 hr which, by 24 hr, was greater than 5-fold that of the untreated CEM cells. No change in MRP mRNA was observed in the CEMRR subline with similar treatment. We conclude that MRP is involved in the immediate response to radiation and it may account for the drug resistance that often develops following radiation treatment.

ATP-Binding Cassette Transporters↗

PubMed2002

Significance of radiation exposure from work-related chest X-rays for epidemiological studies of radiation workers.

BACKGROUND: Previous epidemiologic studies of workers at nuclear weapons facilities have not included X-ray exposures as part of the occupational radiation exposure. The research objective was to determine the contribution of work-related chest X-ray (WRX) exposure relative to the cumulative occupational radiation exposure. METHODS: Cases and controls were identified from a cohort of workers whose employment began as early as 1943. Medical records for 297 subjects were used to determine the bone marrow dose from their X-ray examinations. Individual dose data, however, were only available for 45 workers. Bone marrow dose estimates were calculated by converting the entrance-skin-exposure (from X-ray procedures) and occupational exposure (from monitoring data) to dose. RESULTS: Stereoscopic photofluorography delivered a bone marrow dose nearly 100 times that delivered by today's chest X-ray technique. Photofluorography was the predominant radiation source during the 1940s and 1950s. The cumulative WRX dose was, on average, 50 times their occupational doses. No correlation between occupational and WRX dose was found, but may be due to the small study size and incomplete dose data. CONCLUSIONS: These findings illustrate the importance of including WRX doses in retrospective epidemiological studies of radiation workers, especially if photofluorographic chest X-rays were performed and occupational exposure to ionizing radiation is low.

Bone Marrow↗

PubMed2001

Absence of cervical radiation myelitis after hyperfractionated radiation therapy with and without concurrent chemotherapy for locally advanced, unresectable, nonmetastatic squamous cell carcinoma of the head and neck.

PURPOSE: To evaluate the risk of developing radiation myelitis after a cervical spinal cord dose of 50.6 Gy given via 1.1 Gy b.i.d. fractionation during a prospective, randomised trial of hyperfractionated radiation therapy (HFX RT) to a total dose of 77 Gy given in 70 fractions of 1.1 Gy b.i.d., with and without concurrent low-dose, daily cisplatin (CDDP) for head and neck cancer. METHODS: Of 130 patients with locally advanced, unresectable, nonmetastatic squamous cell carcinoma of the head and neck (SCC H&N) who entered a prospective, randomised trial, 101 patients received 50.6 Gy to a portion of their spinal cord and survived > 1 year following the beginning of therapy. Forty-five patients were treated with HFX RT alone and fifty-six patients also received CDDP. RESULTS: None of these 101 patients developed cervical radiation myelitis. Therefore, it was not possible to investigate the influence of potentially contributing factors on the occurrence of radiation myelitis, such as interfraction interval, cord length, and administration of concurrent CDDP. CONCLUSIONS: Given the increasing number of studies with both altered fractionated regimens and concurrent radio-chemotherapy in SCC H&N, new studies with more patients are needed to gain better insight into the risks of developing cervical radiation myelitis.

Adult↗

PubMed1982

An estimate of the radiation-induced cancer risk from the whole-body stray radiation exposure in neutron radiotherapy.

The 1980 BEIR III risk factors have been used to estimate the secondary cancer risks from the whole-body stray radiation exposures which occur in neutron radiotherapy. The cancer risks have been calculated using the linear, linear-quadratic and quadratic dose-response models for the gamma component of the stray radiation. The linear dose-response model has been used to calculate the risk for the neutron component of the stray radiation. These risk estimates take into consideration for the first time the age and sex distribution of cancer patients undergoing neutron therapy. Changes in the cancer risk as a function of the RBE (10-100) assigned to the stray neutron radiation component have also been assessed. The excess risks in neutron-treated patients have been compared to the excess cancer risks for photon-treated patients and with the expected incidence of cancer in a normal population having the same age and sex distribution. These risk estimates clearly indicate that it will be necessary to tolerate a higher incidence of secondary cancers in patients undergoing fast neutron neutron therapy than is the case with conventional photon therapy. However, for neutron RBEs of less than 50 the increased cancer risk is only a fraction of the normal expected incidence of cancer in this population. Moreover, comparison of the radiation-induced cancer risk with reported normal tissue complication rates in the treatment volume indicates that the excess cancer risk is substantially lower than the risk from other late normal tissue effects.

Adolescent↗

PubMed2006

Final toxicity results of a radiation-dose escalation study in patients with non-small-cell lung cancer (NSCLC): predictors for radiation pneumonitis and fibrosis.

PURPOSE: We aimed to report the final toxicity results on a radiation-dose escalation trial designed to test a hypothesis that very high doses of radiation could be safely administered to patients with non-small-cell lung cancer (NSCLC) by quantifying the dose-volume toxicity relationship of the lung. METHODS AND MATERIALS: A total of 109 patients with unresectable or medically inoperable NSCLC were enrolled and treated with radiation-dose escalation (on the basis of predicted normal-lung toxicity) either alone or with neoadjuvant chemotherapy by use of 3D conformal techniques. Eighty-four patients (77%) received more than 69 Gy, the trial was stopped after the dose reached 103 Gy. Estimated median follow-up was 110 months. RESULTS: There were 17 (14.6%) Grade 2 to 3 pneumonitis and 15 (13.8%) Grade 2 to 3 fibrosis and no Grade 4 to 5 lung toxicity. Multivariate analyses showed them to be (1) not associated with the dose prescribed to the tumor, and (2) significantly (p<0.001) associated with lung-dosimetric parameters such as the mean lung dose (MLD), volume of lung that received at least 20 Gy (V20), and the normal-tissue complication probability (NTCP) of the lung. If cutoffs are 30% for V20, 20 Gy for MLD, and 10% for NTCP, these factors have positive predictive values of 50% to 71% and negative predictive value of 85% to 89%. CONCLUSIONS: With long-term follow-up for toxicity, we have demonstrated that much higher doses of radiation than are traditionally administered can be safely delivered to a majority of patients with NSCLC. Quantitative lung dose-volume toxicity-based dose escalation can form the basis for individualized high-dose radiation treatment to maximize the therapeutic ratio in these patients.

Adult↗

PubMed1977

Interaction of ICRF 159 with radiation, and its effect on sub-lethal and potentially lethal radiation damage in vitro.

ICRF 159 has been shown to increase the X-radiation sensitivity of exponentially growing EMT6 mouse tumour cells in vitro. This was found only with ICRF 159 exposure times longer than 10 h and only when the drug was given before irradiation. The increase in radiation sensitivity was expressed as a reduction of the shoulder of the radiation survival curve. As ICRF 159 was shown to have no effect on the repair of sub-lethal radiation damage, it was concluded that the drug reduced the capacity to accumulate such damage. ICRF 159 was also shown to have no effect on the repair of potentially lethal radiation damage in late plateau cells.

Cell Survival↗

PubMed1994

Increase in mast cells and hyaluronic acid correlates to radiation-induced damage and loss of serous acinar cells in salivary glands: the parotid and submandibular glands differ in radiation sensitivity.

The detailed mechanisms which can explain the inherent radiosensitivity of salivary glands remain to be elucidated. Although DNA is the most plausible critical target for the lethal effects of irradiation, interactions with other constituents, such as cell membrane and neuropeptides, have been suggested to cause important physiological changes. Moreover, mast cells seem to be closely linked to radiation-induced pneumonitis. Therefore, in the present study the effects of fractionated irradiation on salivary glands have been assessed with special regard to the appearance of mast cells and its correlation with damage to gland parenchyma. Sprague-Dawley strain rats were unilaterally irradiated to the head and neck with the salivary glands within the radiation field. The irradiation was delivered once daily for 5 days to a total dose of 20, 35 and 45 Gy. The contralateral parotid and submandibular glands served as intra-animal controls and parallel analysis of glands was performed 2, 4, 10 or 180 days following the last radiation treatment. Morphological analysis revealed no obvious changes up to 10 days after the irradiation. At 180 days a radiation dose-dependent loss of gland parenchyma was seen, especially with regard to serious acinar cells in parotid gland and acinar cells and serous CGT (convoluted granular tubule) cells in the submandibular gland. These changes displayed a close correlation with a concomitant dose-dependent enhanced density of mast cells and staining for hyaluronic acid. This cell population seems to conform with the features of the connective tissue mast cell type. The parotid seems to be more sensitive to irradiation than the submandibular gland. Thus, the present results further strengthen the role of and the potential interaction of mast cells with radiation-induced tissue injury and alterations in normal tissue integrity.

Animals↗

PubMed1999

Cytogenetic analysis in human lymphocytes after exposure to simulated cosmic radiation which reflects the inflight radiation environment.

PURPOSE: To determine the relative biological effectiveness (RBE) of a mixed neutron-gamma-radiation field and its high LET component on the induction of chromosome aberrations in human lymphocytes. MATERIALS AND METHODS: Human lymphocyte cultures were exposed in vitro to low doses of simulated cosmic radiation (2.39-5.81 mGy) at low dose rates (0.04-0.15 mGy/h). Chromosome aberrations, micronuclei, and sister chromatid exchanges (SCE) were analysed. The RBE for dicentric chromosomes was given in comparison to 60Co gamma-rays. RESULTS: For the induction of dicentric chromosomes by simulated cosmic radiation the RBE was up to 64, and up to 113 when calculating only the high LET component. The investigation of micronuclei and SCE showed no significant differences between controls and irradiated samples. CONCLUSIONS: Preliminary data indicate a high biological effectiveness of cosmic radiation and its neutron component in comparison with 60Co gamma-radiation.

Aerospace Medicine↗

PubMed2002

Dose-effect modifying factors in radiation protection--a 1967 National Commission on Radiation Protection document revisited.

In 1967 Subcommittee M-4 of the National Commission on Radiation Protection proposed a system for evaluating, summing and reporting occupational exposures. It appears that some 30 years later these concepts could be implemented in a system of radiation protection based on Katz's cellular track structure model, which is able to quantify and predict the response of systems relevant to radiation protection, such as survival or oncogenic transformations in cell cultures, enzymes, bacteria or whole organisms. As a consequence of this approach, an m-power-law (with m ranging between 2 and 3.5) dependence of effect, or radiation risk, after doses of standard Co-60 radiation, would follow.

Effect Modifier, Epidemiologic↗

PubMed2003

Is radiation protection for the unborn child guaranteed by radiation protection for female workers?

ICRP Publication 88 recommends doses to the embryo and fetus from intakes of radionuclides by the mother for various intake scenarios. Mainly by answering the question 'Is radiation protection for the unborn child guaranteed by radiation protection for female workers?' it has been assessed if the intake scenarios given in ICRP Publication 88 are adequate for radiation protection purposes. This is generally the case, but the consideration of an additional chronic intake scenario for early pregnancy would be helpful. It is demonstrated that following chronic intake by inhalation, for most radionuclides radiation protection for (female) workers is also adequate for protection of the unborn child, considered as a member of the public. However, there are a number of radionuclides for which possible intakes in routine operations should be more restricted (up to 1% of the annual limits on intake for workers in the case of nickel isotopes) to ensure radiation protection for the unborn child.

Computer Simulation↗

PubMed2001

Radiation protection at synchrotron radiation facilities.

A synchrotron radiation (SR) facility typically consists of an injector, a storage ring, and SR beamlines. The latter two features are unique to SR facilities, when compared to other types of accelerator facilities. The SR facilities have the characteristics of low injection beam power, but high stored beam power. The storage ring is generally above ground with people occupying the experimental floor around a normally thin concrete ring wall. This paper addresses the radiation issues, in particular the shielding design, associated with the storage ring and SR beamlines. Normal and abnormal beam losses for injection and stored beams, as well as typical storage ring operation, are described. Ring shielding design for photons and neutrons from beam losses in the ring is discussed. Radiation safety issues and shielding design for SR beamlines, considering gas bremsstrahlung and synchrotron radiation, are reviewed. Radiation source terms and the methodologies for shielding calculations are presented.

Electrons↗