Current status of radiant whole-body hyperthermia at temperatures >41.5 degrees C and practical guidelines for the treatment of adults. The German 'Interdisciplinary Working Group on Hyperthermia'

The term 'extreme' whole-body hyperthermia (WBH) describes the procedure of raising a patients' body-core temperature to 41.5-42.0 degrees C for 60 min. WBH represents the only hyperthermia technique that enables systemic heat treatment in patients with disseminated malignancies and is, therefore, usually combined with systemic chemotherapy. Up to now, several WBH-approaches have proved to be safe and associated with acceptable toxicity rates when radiant heat devices are employed. Until the late 1990s, the use of radiant WBH was restricted to a few specialized treatment centres worldwide. During the last 5 years, a larger number of WBH-devices were put into operation particularly in Germany. As a result, a novel generation on phase II trials on chemotherapy and adjunctive WBH in patients with various malignancies has been completed. Based on the promising results observed herein, first multi-centric phase III-trials on chemotherapy +/- WBH have been initiated, with a considerable number of patients treated at German institutions. The authors are members of the 'Interdisciplinary Working Group for Hyperthermia' ('Interdisziplinäre Arbeitsgruppe Hyperthermie'), a sub-group of the German Cancer Society. They formulated these guidelines in order to standardize the WBH treatment procedure and supportive measures, to provide some uniformity in the selection of patients to be treated and to define criteria of a successful WBH-treatment. These recommendations may be helpful to ensure the quality of WBH performed at different institutions.

Evaluation of radioprotective effects of Rajgira (Amaranthus paniculatus) extract in Swiss albino mice

The radioprotective efficacy of aqueous extract of Rajgira (Amaranthus paniculatus) leaves against whole body gamma radiation was studied in Swiss albino mice. The oral administration of Rajgira extract at 800 mg/kg body weight/day for 15 consecutive days before whole body exposure to radiation was found to be effective with the LD50/30 values of 6.33 and 8.62 Gy for irradiation alone and Rajgira+irradiation group, respectively, giving a dose reduction factor of 1.36. This effect of Rajgira accompanied the increased endogenous spleen colonies and the spleen weight without any side effect or toxicity, as well as the modulation of the radiation-induced decrease of reduced glutathione and the radiation-induced increase in lipid peroxidation assessed in the liver and the blood.

Whole-body exposure to 2.45GHz electromagnetic fields does not alter 12-arm radial-maze with reduced access to spatial cues in rats

Lai et al. [Lai H, Horita A, Guy AW. Microwave irradiation affects radial-arm maze performance in the rat. Bioelectromagnetics 1994;15(2):95-104] reported that exposure of rats to pulsed 2.45 GHz microwaves altered maze performance. Their maze was bordered by 20 cm high opaque walls. Using a maze test based on unrestrained access to spatial cues (no walls), we could not replicate this result [Cassel JC, Cosquer B, Galani R, Kuster N. Whole-body exposure to 2.45 GHz electromagnetic fields does not alter radial-maze performance in rats. Behav Brain Res 2004;155:37-43]. Here, we attempted another replication using a maze apparatus bordered by 30 cm high opaque walls. Performance of exposed rats was normal. These results show that microwave exposure as used herein does not alter spatial working memory, when access to spatial cues is reduced.

Blood–brain barrier and electromagnetic fields: Effects of scopolamine methylbromide on working memory after whole-body exposure to 2.45GHz microwaves in rats

We first verified that our 12-arm radial maze test enabled demonstration of memory deficits in rats treated with the muscarinic antagonist scopolamine hydrobromide (0.5mg/kg, i.p.). We then investigated whether a systemically-injected quaternary-ammonium derivate of this antagonist (scopolamine methylbromide; MBR), which poorly crosses the blood-brain barrier (BBB), altered maze performance after a 45-min exposure to 2.45 GHz electromagnetic field (EMF; 2 micros pulse width, 500 pps, whole-body specific energy absorption rate [SAR] of 2.0 W/kg, +/-2dB and brain averaged SAR of 3.0 W/kg, +/-3 dB); if observed, such an alteration would reflect changes in BBB permeability. The drug was injected before or after exposure. Controls were naive rats (no experience of the exposure device) and sham-exposed rats (experience of the exposure device without microwaves). In a final approach, rats were subjected to i.v. injections of Evans blue, a dye binding serum albumin, before or after EMF exposure. Whether scopolamine MBR was injected before or after exposure, the exposed rats did not perform differently from their naive or sham-exposed counterparts. Thus, EMFs most probably failed to disrupt the BBB. This conclusion was further supported by the absence of Evans blue extravasation into the brain parenchyma of our exposed rats.

Whole-body heating slows carotid baroreflex response in human subjects

Heat stress increases sympathetic activity and decreases parasympathetic activity to the heart. To test the hypothesis that carotid baroreflex responses of heart rate (HR) and systemic blood pressure become slowed with altered autonomic nerve activities during whole-body heat stress, we determined changes in HR and mean arterial pressure (MAP) in response to approximately 5 s of 40 mmHg neck pressure (NP) and of -65 mmHg neck suction (NS) in normothermia and during whole-body heating produced by a hot water-perfused suit. The NP and NS stimuli were triggered by R waves of an ECG during held expiration in the supine position. Whole-body heating did not alter the onset time of the HR and MAP responses during NP and NS. Whole-body heating significantly increased the time from onset of the HR response until peak of the response during NP (2.53 +/- 0.33 s in normothermia and 3.46 +/- 0.28 s during heating, P<0.05) and NS (1.20 +/- 0.23 s and 2.24 +/- 0.29 s, P<0.05). Whole-body heating significantly increased the time from onset of the MAP response until peak of the response during NP (4.31+/-0.46 s in normothermia, 6.67 +/- 0.56 s during heating, P<0.05) but not during NS (5.06 +/- 0.47 s and 4.50 +/- 0.60 s). These findings suggest that heat stress prolongs the response time of carotid-cardiac and carotid-vasomotor baroreflexes.

Genetic factors influencing bystander signaling in murine bladder epithelium after low-dose irradiation in vivo

Radiation-induced bystander effects occur in cells that are not directly hit by radiation tracks but that receive signals from hit cells. They are well-documented in vitro consequences of low-dose exposure, but their relevance to in vivo radiobiology is not established. To investigate the in vivo production of bystander signals, bladder explants were established from two strains of mice known to differ significantly in both short-term and long-term radiation responses. These were investigated for the ability of 0.5 Gy total-body irradiation in vivo to induce production of bystander signals in bladder epithelium. The studies demonstrate that irradiated C57BL/6 mice, but not CBA/Ca mice, produce bystander signals that induce apoptosis and reduce clonogenic survival in reporter HPV-G-transfected keratinocytes. Transfer of medium from explants established from irradiated animals to explants established from unirradiated animals confirmed these differences in bladder epithelium. The responses to the in vivo-generated bystander signal exhibit genotypic differences in calcium signaling and also in signaling pathways indicative of a major role for the balance of pro-apoptosis and anti-apoptosis proteins in determining the overall response. The results clearly demonstrate the in vivo induction of bystander signals that are strongly influenced by genetic factors and have implications for radiation protection, medical imaging, and radiotherapy.

Hematopoietic cell transplantation from HLA-identical sibling donors after low-dose radiation-based conditioning for treatment of CML

A total of 24 patients (median age 58; range, 27-71 years) with chronic myeloid leukemia (CML) in first chronic (CP1) (n=14), second chronic (n=4), or accelerated phase (n=6) who were not candidates for conventional hematopoietic cell transplantation (HCT), received nonmyeloablative HCT from HLA-matched siblings a median of 28.5 (range, 11-271) months after diagnosis. They were conditioned with 2 Gy total body irradiation (TBI) alone (n=8) or combined with fludarabine, 90 mg/m(2) (n=16). Postgrafting immunosuppression included cyclosporine and mycophenolate mofetil. All patients initially engrafted. However, 4 of 8 patients not given fludarabine experienced nonfatal rejection while all others had sustained engraftment. With a median follow-up of 36 (range, 4-49) months, 13 of 24 patients (54%) were alive and in complete remission. There were five (21%) deaths from nonrelapse mortality, one (4%) during the first 100 days after transplant. The proportions of grade II, III, and IV acute GVHD were 38, 4, and 8%, respectively. The 2-year estimate of chronic GVHD was 32%. The 2-year survival estimates for patients in CP1 (n=14) and beyond CP1 (n=10) were 70 and 56%, respectively. This study shows encouraging remission rates for patients with CML not eligible for conventional allografting.

Suppression of Thymic Lymphoma Induction by Life-Long Low-Dose-Rate Irradiation Accompanied by Immune Activation in C57BL/6 Mice

The induction of thymic lymphomas by whole-body X irradiation with four doses of 1.8 Gy (total dose: 7.2 Gy) in C57BL/6 mice was suppressed from a high frequency (90%) to 63% by preirradiation with 0.075 Gy X rays given 6 h before each 1.8-Gy irradiation. This level was further suppressed to 43% by continuous whole-body irradiation with 137Cs gamma rays at a low dose rate of 1.2 mGy/h for 450 days, starting 35 days before the challenging irradiation. Continuous irradiation at 1.2 mGy/h resulting in a total dose of 7.2 Gy over 258 days yielded no thymic lymphomas, indicating that this low-dose-rate radiation does not induce these tumors. Further continuous irradiation up to 450 days (total dose: 12.6 Gy) produced no tumors. Continuously irradiated mice showed no loss of hair and a greater body weight than unirradiated controls. Immune activities of the mice, as measured by the numbers of CD4+ T cells, CD40+ B cells, and antibody-producing cells in the spleen after immunization with sheep red blood cells, were significantly increased by continuous 1.2-mGy/h irradiation alone. These results indicate the presence of an adaptive response in tumor induction, the involvement of radiation-induced immune activation in tumor suppression, and a large dose and dose-rate effectiveness factor (DDREF) for tumor induction with extremely low-dose-rate radiation.

Cytological basis for enhancement of radiation-induced mortality by Friend leukaemia virus infection

PURPOSE

To analyse the cytological basis for enhancement of radiation-induced mortality by Friend leukaemia virus infection.

MATERIALS AND METHODS

Cellularity in haematopoietic tissues of C3H mice infected with FLV and/or whole-body irradiation was examined.

RESULTS

When mice were treated with a sublethal dose (3 Gy) of irradiation at 1 week after virus infection, most manifested a severe loss of cellularity in the spleen, bone marrow and peripheral blood 2 weeks after irradiation. More than 90% of the mice died within 1 month post-irradiation. However, this deleterious effect of virus infection on the survival of irradiated mice was observed only when they were irradiated at around 1 week after virus inoculation. Strain differences in the sensitivity to this effect were observed among virus-sensitive strains of mice.

CONCLUSIONS

The results indicate that Friend leukaemia virus infection can cause enhancement of radiation sensitivity of haematopoietic cells in host animals in a restricted manner in terms of genetic background and the interval between infection and irradiation.

The efficacy and reliability of lung protection during total body irradiation of patients with disseminated malignancies

The main problem in total body irradiation (TBI) is obtaining a homogenous dose distribution inside the whole irradiated body and ensuring appropriate dose reduction in the lungs. The process of irradiation should be comfortable for the patients and repeatable despite the size and age diversity among patients. The aim of this paper was 1) to check accuracy of the applied dose algorithm and reliability of the measurement technique used in the lung region during TBI taken alternatively on a Cobalt-60 unit and on 15 MV linear accelerators, and 2) to check if the described methodology made it possible to obtain reproducibly of the lowered level of the dose to the lungs for a diverse group of patients. TBI was performed as a preparatory regiment in children and adults with disseminated malignancies undergoing bone marrow transplantation (a dose of 12.6 Gy in the midline/central beam axis). Two consecutive groups of patients were retrospectively included in the study: 15 irradiated with Cobalt-60 and 15 with 15 MV photons. The doses were evaluated for three sections passing through the middle of the lungs and at their upper and lower sides. Two types of detectors: semiconductor and thermoluminescent ones were used simultaneously. The measured doses were evaluated statistically to reveal agreement between readings of the two types of detectors and agreement between the measured doses and those previously calculated. The results of measurements exhibited a not Gaussian-type distribution (dissymmetry). The Wilcoxon-type test revealed compliance between the doses measured with thermoluminescent (TL) and semiconductor (SEM) detectors for all sections passing through the lungs (p>0.05), excluding the lung exit (middle and lower sides) with the Cobalt therapy. The t-Student test used to compare the measured doses with those previously calculated revealed agreement (p>0.05) between the measured doses and those calculated for all lung sections for the 15 MV photon therapy, while for Cobalt therapy such an agreement was at some points doubtful. The calculation algorithm and measurement techniques have proved to be correct, which was revealed by agreement between the doses measured and those calculated. The shielding of the lungs during both types of fields was effective and reproducible as indicated by agreement between the doses measured with the two types of detectors. Better agreement between the measured and calculated doses was found for 15 MV photons than for the Cobalt unit.

[Effectiveness of repeated systematic radiotherapy for generalized prostate cancer]

Examination of 127 patients with generalized prostate cancer established a low prophylactic effect of systematic treatment with strontium-39 chloride: it failed to alleviate pain in metastatic cancer, nor was it followed by longer mean survival. Repeat systematic radiotherapy is not indicated when palliative measures such as hormonal therapy, local radiotherapy and chemotherapy are still effective.

Low dose total body irradiation followed by allogeneic lymphocyte infusion for refractory hematologic malignancy--an updated review

Allogeneic stem cell transplantation is curative for certain cancers, but the high doses of chemotherapy and radiotherapy used in conventional myeloablative conditioning regimens may lead to severe toxicity. In our initial study, we treated 25 patients with refractory cancers with 100 cGy total body irradiation (TBI) followed by allogeneic, non mobilized peripheral blood cells. Eighteen patients received sibling and 7 patients received unrelated cord blood stem cells. None of the 13 patients with solid tumors achieved donor chimerism or had a sustained response. Twelve patients with hematologic malignancies were treated, 1 received a cord blood transplant and 11 received sibling donor cells. Nine of these 11 patients achieved donor chimerism, ranging from 5% to 100%. Four patients had sustained complete remission of their cancers, and 2 are long-term survivors. The development of chimerism correlated with total previous myelotoxic chemotherapy (p < 0.001). This technique is now being extended into the haploidentical setting.

Effect of dose-rate and lung dose in total body irradiation on interstitial pneumonitis after bone marrow transplantation

The aim of this study is to evaluate the incidence of interstitial pneumonitis following fractionated total body irradiation conditioning for bone marrow transplantation with varying lung doses due to shielding technique and different dose-rates. Between 1987 and 2001, a total number of 105 patients have received total body irradiation conditioning for bone marrow transplantation for hematological malignancies at Gulhane Military Medical School. Twelve Gy fractionated total body irradiation was delivered in 6 fractions over 3 consecutive days with Co-60 teletherapy machine. Conditioning therapy included only cyclophosphamide (60 mg/ kg/day for two days) and total body irradiation. The median follow-up for patients was 12 months. Interstitial pneumonitis developed in 10 patients out of 105 patients (9.52%). The median total dose to lung was 9.60 Gy (8.88-10.90). The difference between total lung dose and interstitial pneumonitis was not significant. Pneumonitis development in the high dose-rate (>0.04 Gy/min) group versus low dose-rate (< or =0.04 Gy/min) group was statistically significant. Low dose-rate fractionated total body irradiation is a reliable conditioning program in bone marrow transplantation with effective lung sparing to avoid interstitial pneumonitis.

Whole-body exposure to 2.45 GHz electromagnetic fields does not alter radial-maze performance in rats

Mobile communication is based on utilization of electromagnetic fields (EMFs) in the frequency range of 0.3-300 GHz. Human and animal studies suggest that EMFs, which are in the 0.1 MHz-300 GHz range, might interfere with cognitive processes. In 1994, a report by Lai et al. [Bioelectromagnetics 15 (1994) 95-104] showed that whole-body exposure of rats to pulsed 2.45 GHz microwaves (2 micros pulse width, 500 pps, and specific absorption rate [SAR] 0.6 W/kg) for 45 min resulted in altered spatial working memory assessed in a 12-arm radial-maze task. Surprisingly, there has been only one attempt to replicate this experiment so far [Bioelectromagnetics 25 (2004) 49-57]; confirmation of the Lai et al. experiment failed. In the present study, rats were tested in a 12-arm radial-maze subsequently to a daily exposure to 2.45 GHz microwaves (2 micros pulse width, 500 pps, and SAR 0.6 W/kg) for 45 min. The performance of exposed rats was comparable to that found in sham-exposed or in naive rats (no contact with the exposure system). Regarding the methodological details provided by Lai et al. on their testing protocol, our results might suggest that the microwave-induced behavioral alterations measured by these authors might have had more to do with factors liable to performance bias than with spatial working memory per se.

Effects of whole-body 50-Hz magnetic field exposure on mouse Leydig cells

The main goal of this study was to evaluate the possible effect of whole-body magnetic field (MF) exposure on the steroidogenic capacity of Leydig cells in vitro. In four separate experiments, male CFLP mice were exposed to sinusoidal 50-Hz, 100-microT MF. The duration of exposure was 23.5 h/day over a period of 14 days. At the end of the exposure, interstitial (Leydig) cells were isolated from the testicles of the sham-exposed and exposed animals. The cells were cultured for 48 h in the presence or absence of 1, 10, or 100 mIU/ml human chorionic gonadotropin (hCG). The luteinizing hormone (LH) analog hCG was used to check the testosterone (T) response of the sham-exposed controls and to evaluate the possible effect of the whole-body MF exposure on the steroidogenic capacity of Leydig cells in vitro. Testosterone content of the culture media and blood sera was measured by radioimmunoassay (RIA). In the cultures obtained from MF-exposed animals, the hCG-stimulated T response was significantly higher (p < 0.01) compared with the sham-exposed controls, while the basal T production of cells and the level of serum T remained unaltered. No MF exposure-related histopathological alterations were found in testicles, epididymes, adrenals, prostates, and pituitary glands. The MF exposure did not affect the animal growth rate and the observed hematologic and serum chemical variables. Our results indicate a presumably direct effect of whole-body MF exposure on the hCG-stimulated steroidogenic response of mouse Leydig cells.

CT-based analysis of dose homogeneity in total body irradiation using lateral beam

A computed tomography (CT) based treatment planning system for total body irradiation (TBI) is presented and compared with the commonly practiced lateral treatment delivery. The TBI regimen has been proved to be an essential conditional regimen for patients undergoing bone marrow transplantation. The advantage of the TBI regimen with bone marrow transplantation (BMT) in hematological malignancies can be offset by toxicities arising from TBI in posttransplant complications. With the increasing survival rates, the evaluation of long‐term side effects and quality of life has become an important area of research interest. There have been several treatment techniques developed over the decades designed to achieve accurate dose delivery and dose homogeneity. This paper reports on the verification of the dose delivery for a basic lateral technique using thermoluminescent dosimeters (TLDs) placed in an anthropomorphic phantom and its correlation with CT‐based treatment planning. CT‐based treatment plans on several patients were used to evaluate the doses delivered to the whole body and critical organs. A large variation in doses delivered to the whole body was demonstrated, with some parts of the bone marrow failing to receive the prescribed dose and some critical organs, such as the lungs, receiving excessive doses. Placing the arms at the sides only partially compensates for the increased transmission of the lungs because the arms only shadow part of the lung. This study shows that CT‐based treatment planning for TBI provides precise and accurate dose calculations and allows for the correlation of clinical outcomes with the doses actually delivered to various organs.

PACS numbers: 87.53.Dq, 87.66.Xa, 87.66.Sq

Morphology of cerebral lesions in the Eker rat model of tuberous sclerosis

Tuberous sclerosis (TSC) is an autosomal dominant disorder, caused by mutations of either the TSC1 or TSC2 gene. Characteristic brain pathologies (including cortical tubers and subependymal hamartomas/giant astrocytomas) are thought to cause epilepsy, as well as other neurological dysfunction. The Eker rat, which carries a spontaneous germline mutation of the TSC2 gene (TSC2+/-), provides a unique animal model in which to study the relationship between TSC cortical pathologies and epilepsy. In the present study, we have analyzed the seizure propensity and histopathological features of a modified Eker rat preparation, in which early postnatal irradiation was employed as a "second hit" stimulus in an attempt to exacerbate cortical malformations and increase seizure propensity. Irradiated Eker rats had a tendency toward lower seizure thresholds (latencies to flurothyl-induced seizures) than seen in non-irradiated Eker rats (significant difference) or irradiated wild-type rats (non-significant difference). The majority of irradiated Eker rats exhibited dysplastic cytomegalic neurons and giant astrocyte-like cells, similar to cytopathologies observed in TSC lesions of patients. The most prominent features in these brains were hamartoma-like lesions involving large eosinophilic cells, similar to giant tuber cells in human TSC. In some cells from these hamartomas, immunocytochemistry revealed features of both neuronal and glial phenotypes, suggesting an undifferentiated or immature cell population. Both normal-appearing and dysmorphic neurons, as well as cells in the hamartomas, exhibited immunopositivity for tuberin, the protein product of the TSC2 gene.

Differential qualitative and temporal changes in the response of the hypothalamus-pituitary-adrenal axis in rats after localized or total-body irradiation

Stress such as exposure to ionizing radiation is able to activate the hypothalamus-pituitary-adrenal axis. The present study sought to examine the effects of different configurations of a 10-Gy gamma irradiation in rats on the hypothalamus-pituitary-adrenal axis to understand the mechanism of negative feedback by glucocorticoids induced by ionizing radiation. Specifically, we determined adrenocorticotropin and corticosterone levels in plasma as well as corticotrophin-releasing factor expression in the paraventricular nucleus of the hypothalamus by in situ hybridization from 6 h to 4 days after total-body, abdominal or head irradiation. In this study, we found an activation of the hypothalamus-pituitary-adrenal axis after radiation exposure. Plasma adrenocorticotropin and corticosterone levels were significantly increased after total-body and abdominal irradiation 3 days after exposure, in parallel with decreased labeling of corticotrophin-releasing factor mRNA in the parvocellular region of the paraventricular nucleus of the hypothalamus. Our results suggest that ionizing radiation activates the neuroendocrine system to protect the organism from the occurrence of radiation-induced inflammation.

Matching the dosimetry characteristics of a dual-field Stanford technique to a customized single-field Stanford technique for total skin electron therapy

PURPOSE

To compare the dosimetry characteristics of a customized single-field and a matching dual-field electron beam for total skin electron therapy (TSET) within the framework of the Stanford technique. To examine and quantify its impact on patient dosimetry.

METHODS AND MATERIALS

Two characteristically different electron beams were used for TSET employing the Stanford technique: a single-field beam created from a pencil beam of electrons passing through 7 meters of air and a dual-field beam created from two heavily scattered electron beams directed at oblique angles to patients. The dosimetry characteristics of the two beams were measured by using ionization chambers, radiographic films, and thermal luminescent detectors. The impact of beam characteristic on patient dosimetry was quantified on both anthromorphic phantoms and on patients. Treatment protocols aimed at matching the patient dose between the two systems were established on the basis of these and other measurements.

RESULTS

The dual-field beam was matched to the single-field beam, resulting in approximately the same mean energy (approximately 4.0 MeV) and most probable energy (approximately 4.5 MeV) at their respective treatment source-to-patient-surface distance (SSD). The depth dose curves on the beam axis were nearly identical for both beams. X-ray contamination on the beam axis was 0.43% for the dual-field beam, slightly higher than that (0.4%) of the single-field beam. The beam uniformity, however, was quite different: the dual-field beam was more uniform in the vertical direction but was worse in the lateral direction compared to the single-field beam. For a TSET treatment using the Stanford technique, the composite depth dose curves were nearly identically at the level of beam axis: with an effective depth of maximum buildup (d(max)) at approximately 1 mm below the skin surface and the depth to 80% depth dose at around 6 mm. The overall X-ray contamination was approximately 1.0% and 1.2% for the single-field and dual-field system, respectively. Away from the beam axis level, treatment using either beam was able to deliver over 90% of prescription dose to the main body surfaces. For body surfaces tangential to the beam axis (e.g., top of head and shoulders), the dose was low especially when using the dual-field beam. By adding boost radiation to the tangential surfaces and by adjusting the planned shielding for critical structures, the total dose to the patient over a complete course of TSET treatment could be matched closely for the two systems.

CONCLUSIONS

Although the depth doses can be matched at the level of the beam axis, there exist some characteristic differences in the angular distribution of the electrons between the large SSD single-field beam and the short SSD dual-field beam. These differences resulted in lower dose delivered to "tangential" body surfaces and to body structures that extended farther laterally when using the dual-field beam. However, by adjusting the treatment protocol regarding the boost irradiation and planned shielding, the total dose to patients from a complete course of TSET treatment using the dual-field beam can be matched to that given by the single-field beam. Special attention should be paid to the dosimetry at the "tangential" body surfaces when commissioning a dual-field TSET system.

IL-1beta, TNFalpha and IL-6 induction in the rat brain after partial-body irradiation: role of vagal afferents

PURPOSE

To evaluate the central nervous system neuroimmune and inflammatory responses during the prodromal phase of the acute irradiation syndrome in rat brains after partial-body exposure (head-protected) and to investigate the potential neural signalling pathways from the irradiated periphery to the non-irradiated brain.

MATERIAL AND METHODS

The study included four groups of rats: one irradiated group and one sham irradiated group, each containing non-vagotomized and vagotomized rats. In vagotomized rat groups, the subdiaphragmatic vagal section surgery was carried out 45 days before the irradiation exposure. The rats were partial-body irradiated with the head shielded with (60)Co gamma-rays to a dose of 15 Gy. They were sacrificed 6 h after the end of exposure. The hypothalamus, hippocampus, thalamus and cortex were then collected, and the concentrations of IL-1beta, TNFalpha and IL-6 in each were measured by ELISA assays.

RESULTS

Six hours after irradiation, IL-1beta levels had increased in the hypothalamus, thalamus and hippocampus, and TNFalpha and IL-6 levels had increased significantly in the hypothalamus. Vagotomy before irradiation prevented these responses.

CONCLUSIONS

It was concluded that the hypothalamus, hippocampus, thalamus and cortex react rapidly to peripheral irradiation by releasing pro-inflammatory mediators. The results also show that the vagus nerve is one of the major ascending pathways for rapid signalling to the brain with respect to partial body irradiation.

Prolongation of Life Span Associated with Immunological Modification by Chronic Low-Dose-Rate Irradiation in MRL-lpr/lprMice

Chronic low-dose-rate gamma irradiation at 0.35 or 1.2 mGy/h prolonged the life span of MRL-lpr/lpr mice carrying a deletion in the apoptosis-regulating Fas gene that markedly shortens life due to severe autoimmune disease. Immunological modifications as indicated by a significant increase of CD8(+) T cells and a significant decrease of CD3(+) CD45R/B220(+) as well as CD45R/B220(+) CD40(+) cells were found in parallel with amelioration of total-body lymphadenopathy, splenomegaly, proteinuria, and kidney and brain syndromes.

Dosimetric analysis of the carousel setup for the exposure of rats at 1.62 GHz

The so-called carousel setup has been widely utilized for testing the hypotheses of adverse health effects on the central nervous system (CNS) due to mobile phone exposures in the frequency bands 800-900 MHz. The objectives of this article were to analyze the suitability of the setup for the upper mobile frequency range, i.e., 1.4-2 GHz, and to conduct a detailed experimental and numerical dosimetry for the setup at the IRIDIUM frequency band of 1.62 GHz. The setup consists of a plastic base on which ten rats, restrained in radially positioned tubes, are exposed to the electromagnetic field emanating from a sleeved dipole antenna at the center. Latest generation miniaturized dosimetric E field and temperature probes were used to measure the specific absorption rate (SAR) inside the brain of three rat cadavers of the Lewis strain and two rat cadavers of the Fisher 344 strain. A numerical analysis was conducted on the basis of three numerical rat phantoms with voxel sizes between 1.5 and 0.125 mm3 that are based on high resolution MRI scans of a 300 g male Wistar rat and a 370 g male Sprague-Dawley rat. The average of the assessed SAR values in the brain was 2.8 mW/g per W antenna input power for adult rats with masses between 220 and 350 g and 5.3 mW/g per W antenna input power for a juvenile rat with a mass of 95 g. The strong increase of the SAR in the brain with decreasing animal size was verified by simulations of the absorption in numerical phantoms scaled to sizes between 100 and 500 g with three different scaling methods. The study also demonstrated that current rat phantom models do not provide sufficient spatial resolution to perform absolute SAR assessment for the brain tissue. The variation of the SAR(brain)(av) due to changes in position was assessed to be in the range from +15% to -30%. A study on the dependence of the performance of the carousel setup on the frequency revealed that efficiency, defined as SAR(brain)(av) per W antenna input power, and the ratio between SAR(brain)(av) and SAR(body)(av) are optimal in the mobile communications frequency range, i.e., 0.8-3 GHz.

Total skin electron beam radiotherapy for patients who have mycosis fungoides

It has taken four decades of basic and clinical research to bring about a consensus process and published report that recognize a TSEB radiotherapy technique that is optimized from several perspectives (see references [2-4, 13]). Short and long-term clinical results with consensus TSEB radiotherapy technique are good. The therapeutic ratio of TSEB radiotherapy is well-defined and is clinically acceptable. Meanwhile, adjuvant PUVA and ECP may significantly improve results, but further data are needed to confirm these preliminary findings (see references [23, 34, 39, 40, 42]).

Empirical and theoretical dosimetry in support of whole body resonant RF exposure (100 MHz) in human volunteers

This study reports the dosimetry performed to support an experiment that measured physiological responses of volunteer human subjects exposed to the resonant frequency for a seated human adult at 100 MHz. Exposures were performed in an anechoic chamber which was designed to provide uniform fields for frequencies of 100 MHz or greater. A half wave dipole with a 90 degrees reflector was used to optimize the field at the subject location. The dosimetry plan required measurement of transmitter harmonics, stationary probe drift, field strengths as a function of distance, electric and magnetic field maps at 200, 225, and 250 cm from the dipole antenna, and specific absorption rate (SAR) measurements using a human phantom, as well as theoretical predictions of SAR with the finite difference time domain (FDTD) method. On each exposure test day, a measurement was taken at 225 cm on the beam centerline with a NBS E field probe to assure consistently precise exposures. A NBS 10 cm loop antenna was positioned 150 cm to the right, 100 cm above, and 60 cm behind the subject and was read at 5 min intervals during all RF exposures. These dosimetry measurements assured accurate and consistent exposures. FDTD calculations were used to determine SAR distribution in a seated human subject. This study reports the necessary dosimetry for work on physiological consequences of human volunteer exposures to 100 MHz.