Effects of GSM-900 microwaves on DMBA-induced mammary gland tumors in female Sprague-Dawley rats

The aim of this investigation was to test the hypothesis that sub-chronic whole-body exposure to GSM-900 microwaves had an effect on tumor promotion and progression. Mammary tumors were induced by ingestion of a single 10-mg dose of 7,12-dimethylbenz(a)anthracene (DMBA) in female Sprague-Dawley rats (Ico:OFA-SD; IOPS Caw). In two independent experiments, DMBA-treated animals were divided into four groups: sham-exposed (16) and exposed (three groups of 16 animals). The specific absorption rates (SARs), averaged over the whole body, were 3.5, 2.2 and 1.4 W/kg in the first experiment (May-July) and 1.4, 0.7 and 0.1 W/kg in the second experiment (September-November). Exposure started 10 days after DMBA treatment and lasted 2 h/day, 5 days/week for 9 weeks. Animals were exposed to plane waves with the electric field parallel to the long axis of the animals. Body weight and the number, location and size of the tumors were recorded at regular intervals. Rats were killed humanely 3 weeks after the end of exposure. The results are negative in terms of latency, multiplicity and tumor volume. With regard to tumor incidence, in the first experiment there was an increase in the rate of incidence at 1.4 W/kg but less at 2.2 W/kg and none at 3.5 W/kg. Overall, these results, which are rather inconsistent, do not bring new evidence of a co-promoting effect of exposure to GSM-900 signals using the DMBA rat model.

Thermophysiological consequences of whole body resonant RF exposure (100 MHz) in human volunteers

Thermophysiological responses of heat production and heat loss were measured in seven adult volunteers (six males and one female, aged 31-74 years) during 45 min dorsal exposures of the whole body to 100 MHz continuous wave (CW) radio frequency (RF) energy. Three power densities (PD) (average PD = 4, 6, and 8 mW/cm(2); whole body specific absorption rate [SAR] = 0.068 [W/kg]/[mW/cm(2)]) were tested in each of three ambient temperatures (T(a) = 24, 28, and 31 degrees C), as well as in T(a) controls (no RF). A standardized protocol (30 min baseline, 45 min RF or sham exposure, 10 min baseline) was used. Measured responses included esophageal and seven skin temperatures, metabolic heat production, local sweat rate, and local skin blood flow. No changes in metabolic heat production occurred under any test condition. Unlike published results of similar exposures at 450 and 2450 MHz, local skin temperatures, even those on the back that were irradiated directly, changed little or not at all during 100 MHz exposures. The sole exception was the temperature of the ankle skin, which increased by 3-4 degrees C in some subjects at PD = 8 mW/cm(2). During the 45 min RF exposure, esophageal temperature showed modest changes (range = -0.15 to 0.13 degrees C) and never exceeded 37.2 degrees C. Thermoregulation was principally controlled by appropriate increases in evaporative heat loss (sweating) and, to a lesser extent, by changes in skin blood flow. Because of the deep penetration of RF energy at this frequency, effectively bypassing the skin, these changes must have been stimulated by thermal receptors deep in the body rather than those located in the skin.

Inhibitory effect of local ischaemic preconditioning in total body irradiated rats

The aim of this study was to explore the relationship between local ischaemic preconditioning and the effectiveness of fractionated radiotherapy. The rat serum, bone marrow, and small intestine were examined for oxidative changes induced by total body irradiation with gamma rays with applied local ischaemic preconditioning immediately before irradiation. Serum concentrations of TBA-RS examined 12 hours after the last irradiation did not reveal any differences among the groups of animals analyzed. Twenty-four hours after the last dose of irradiation, the serum concentrations of TBA-RS varied in particular groups (P<0.0001). The concentration of triglycerides in the serum of local preconditioned ischaemia and irradiated animals showed a reversed shape similar to the TBA-RS fluctuation (P<0.003). The level of uric acid in the serum of animals treated only with radiation is slightly higher than the level of this acid in the serum of the local preconditioned ischaemia radiation group (P<0.58). The number of bone marrow polychromatic erythrocytes did not appear to differ substantially in both irradiated groups. At the first 12 hours after irradiation, the frequency of micronucleated polychromatic erythrocytes is significantly different in the bone marrow of both groups either in combination with ischaemic preconditioned radiation or with radiation alone (P<0.0002). In irradiated animals without ischaemic preconditioning, on the 3rd day after irradiation the number of crypts increased and in the next days decreased achieving the level of the control group on the 7th day. Irradiated rats with local ischaemic preconditioning did not reveal an increase in the number of crypts. The difference was statistically significant (P<0.05). These data indicate that the local ischaemic preconditioning modifies the radiation peroxidising effects through inhibition of free radical-dependent lipid peroxidation and, probably, other unrecognized mechanisms.

Hematopoietic recovery following autologous bone marrow transplantation in a nonhuman primate: effect of variation in treatment schedule with PEG-rHuMGDF

Mathematical modeling of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) pharmacokinetics (PK) and pharmacodynamics (PD) suggest that variations in the PEG-rHuMGDF treatment schedule could reduce the severity and duration of thrombocytopenia following myeloablation and bone marrow transplant (BMT). We tested this hypothesis in a rhesus monkey model of autologous (Au) bone marrow-derived mononuclear cell (BM-MNC) transplantation following lethal myeloablation. On day 0, animals were myeloablated by total body exposure to 920 cGy, 250 kVp x-irradiation (TBI). Four cohorts of animals were infused with 1 x 10(8) AuBM-MNC/kg body weight within 2 hours of TBI. The AuBMT-alone cohort received no cytokine, the daily dosage cohort received PEG-rHuMGDF (2.5 micro g/kg/day, s.c.) post TBI and AuBMT, and the pre/post-transplant cohort received PEG-rHuMGDF (2.5 micro g/kg/day, s.c.) pre (day -9 to day -5) and post TBI and AuBMT. The post-transplant PEG-rHuMGDF administration in the above cohorts was begun on day 1 post TBI and continued until platelet counts reached 200,000 micro l (range, 15-31 days). Another group received PEG-rHuMGDF (300 micro g/kg/day, s.c.) on days 1 and 3 only following TBI and AuBMT. The TBI controls received neither AuBMT nor cytokine therapy. In this model of AuBMT, with regard to the PEG-rHuMGDF administration schedule, the daily dosage of the post-transplant cohort did not significantly improve platelet recovery; the pre/post-transplant schedule and an abbreviated high-dosage, post-transplant schedule (days 1 and 3) significantly improved the duration and nadir of thrombocytopenia and platelet recovery. These data confirm predictions from PK/PD modeling of PEG-rHuMGDF that thrombocytopenia is preventable following AuBMT.

Phase I study of escalating doses of low-dose-rate, locoregional irradiation preceding Cytoxan-TBI for patients with chemotherapy-resistant non-Hodgkin's or Hodgkin's lymphoma

PURPOSE

In patients in whom bone marrow transplantation (BMT) fails, recurrence often occurs at sites known to have contained disease before initiating BMT. The purpose of this study was to find the maximal tolerable dose of locoregional irradiation (LRT) between 1000 and 2000 cGy that could be integrated with our Cytoxan-total body irradiation (TBI) BMT conditioning regimen in the treatment of lymphoma.

METHODS AND MATERIALS

Patients had Hodgkin's or non-Hodgkin's lymphoma in chemotherapy-refractory relapse. All patients received LRT to a maximum of three sets of fields encompassing either all current or all previously known sites of disease. Cytoxan-TBI consisted of cyclophosphamide 50 mg/kg daily for 4 days followed by TBI of 1200 cGy given in four fractions.

RESULTS

Twenty-one patients were enrolled. Radiation Therapy Oncology Group Grade 3 in-field acute toxicity was observed in 1 patient at each dose level up to 1500 cGy and in 3 of 6 patients receiving 2000 cGy. Clinically evident late toxicities were limited to hypothyroidism and one second malignancy occurring outside the LRT fields.

CONCLUSION

Low-dose-rate, LRT with concurrent Cytoxan-TBI before BMT has acceptable rates of in-field toxicity for doses up to 1500 cGy in five fractions. This regimen safely permits the use of a total combined radiation dose of up to 2700 cGy during 2 weeks, with encouraging in-field response rates in treatment-refractory patients.

Comparisons of pulmonary carcinogenesis in rats following inhalation exposure to plutonium dioxide or X-ray irradiation

Radiation-induced pulmonary carcinogenesis was compared in female Wistar rats following either inhalation exposure to alpha-emitting (239)PuO(2) aerosols, whole-body or thoracic X-ray irradiation. Dose-dependent survival reduction was correlated with increased malignant lung tumors at doses over 0.45 Gy, reaching the maximum incidence of 90% at 6.6-8.5 Gy in (239)Pu-exposed rats. While the differential dose responses for each histopathological type of tumors were noted, almost 70-80% were carcinomas among all of the primary tumors from (239)Pu-exposed rats. As the dose response curves for lung carcinomas were compared, the slope of the fit linear equation and the calculated relative effectiveness for 50% incidence of lung carcinomas were approximately 11-times as high in (239)Pu-exposure as those of thoracic X-irradiation. The numbers of tumor lesions distributed in the lung per tumor-bearing animal were about 2-fold more in (239)Pu-exposed rats, while the proportions of their histopathological types were similar between (239)Pu-exposure and X-irradiation. These results indicate that the magnitudes of the relative effectiveness or risk for pulmonary carcinogenesis are greater in (239)Pu-exposure than X-irradiation, and that radiation-induced lung tumors appear to originate mostly from the same target epithelial cells.

Physical models and dose factors for use in internal dose assessment

Internal dose assessment depends on the use of mathematical formulas for dose calculation and models of the human body and its organs. A simple, unified method for internal dose calculations is described, which brings together and simplifies concepts used in nuclear medicine and occupational internal dose systems previously described. Using the best current decay data and phantoms for internal dose calculations, dose factors for internal dose assessment are provided. Decay data for over 800 radionuclides from the data service at Brookhaven National Laboratory were combined with absorbed fraction data from a number of currently available mathematical whole body and organ models to provide the dose factors. This represents the first published update on nuclear medicine dose factors since MIRD Pamphlet No. 11 in 1975; in this paper, dose factors for many more nuclides are given (816 vs. 117 in MIRD 11), including some alpha emitters. New models are also employed, and dose factors for bone and marrow have been updated with recently suggested corrections. The good agreement of the new dose factors with previously published values for several of the models gives good confidence in their accuracy. This article gives an overview of the technical basis for these dose factors and some example tables of data, but the bulk of the data files will be distributed electronically. The use of an "electronic publishing" approach permits the publication of this kind of voluminous information in mainstream journals while facilitating rapid access and use without the need to purchase often expensive and bulky paper documents.

Effect of extended exposure to low-dose radiation on autoimmune diseases of immunologically suppressed MRL/MpTn-gld/gld mice

The purpose of this paper is to analyze the relationship between alterations of splenic T-cell subpopulations and the amelioration of autoimmune diseases of MRL/MpTn-gld/gld mice (MRL/gld mice) after extended exposure to low-dose radiation. After the onset of disease, 4-month-old MRL/gld mice were exposed to doses of 0.05, 0.2, and 0.5 Gy/day for 4 weeks (5 days/week), for total doses of 1, 4, and 10 Gy, respectively. The MRL/gld mice that were irradiated with 0.2 and 0.5 Gy/day showed an obvious decrease in the proportion of splenic CD4(-)CD8(-) T cells and remission of their autoimmune diseases. After the last irradiation, apoptotic cells were found in the white pulp of the spleen of the MRL/gld mice irradiated with 0.2 Gy/day, but not in the MRL/MpJ-+/+ mice (MRL/wild mice), which experienced a similar treatment. Before the onset of disease, 3-month-old MRL/gld mice subjected to 0.2 Gy/day showed a decrease in the proportion of splenic CD4(-)CD8(-) T cells and less remission of their autoimmune diseases than the 4-month-old mice. These results suggest that the accumulated CD4(-)CD8(-) T cells are more sensitive to radiation than other T-cell subpopulations, and that decreasing CD4(-)CD8(-) T cells with extended exposure to low-dose radiation leads to the amelioration of autoimmune disease.

Skin temperature changes induced by strong static magnetic field exposure

High intensity static magnetic fields, when applied to the whole body of the anesthetized rat, have previously been reported to decrease skin temperature. The hypothesis of the present study was that in diamagnetic water, molecules in the air play significant roles in the mechanism of skin temperature decrease. We used a horizontal cylindrical superconducting magnet. The magnet produced 8 T at its center. A thermistor probe was inserted in a subcutaneous pocket of the anesthetized rats to measure skin temperature. Animals (n=10) were placed in an open plastic holder in which the ambient air was free to move in any direction (group I). Animals (n=10) were placed in a closed holder in which the air circulation toward the direction of weak magnetic field was restricted (group II). Each holder was connected to a hydrometer to measure humidity around the animal in the holder. The data acquisition phase consisted of a 5 min baseline interval, followed by inserting the animal together with the holder into the center of the magnet bore for a 5 min exposure and a 5 min postexposure period outside the bore. In group I, skin temperature and humidity around the animal significantly decreased during exposure, followed by recovery after exposure. In group II, skin temperature and humidity did not decrease during the measurement. The skin temperature decrease was closely related to the decrease in humidity around the body of the animal in the holder, and the changes were completely blocked by restricting the air circulation in the direction of the bore entrance. Possible mechanisms responsible for the decrease in skin temperature may be associated with magnetically induced movement of water vapor at the skin surface, leading to skin temperature decrease.

Melatonin protects rat liver against irradiation-induced oxidative injury

The aim of this study was to investigate the antioxidant roles of different doses of melatonin (5 and 10 mg x kg (-1) ) against gamma-irradiation-caused oxidative damage in liver tissue after total body irradiation (TBI) with a single dose of 6.0 Gy. Fifty adult rats were divided into 5 equal groups, 10 rats each. Groups I and II were injected with 5 and 10 mg x kg (-1) of melatonin, and group III was injected with an isotonic NaCl solution. Group IV was injected with only 5 mg x kg (-1) of melatonin. Group V was reserved as a sham control. Following a 30-min-period, 6.0 Gy TBI was given to groups 1, 2 and 3 in a single fraction. The liver malondialdehyde (MDA) levels, super oxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured in all groups. TBI resulted in a significant increase in the liver tissue MDA levels and a decrease of SOD and GSH-Px activities. The results demonstrated that the liver tissue MDA levels in irradiated rats that were pretreated with melatonin (5 or 10 mg x kg (-1) ) were significantly decreased, while the SOD and GSH-Px activities were significantly increased. Decreasing the MDA levels by melatonin was dose dependent, but the liver tissue SOD and GSH activities were not. The data obtained in this study suggest that melatonin administration prior to irradiation may prevent liver damage by irradiation.

A Monte Carlo-based method to estimate radiation dose from spiral CT: from phantom testing to patient-specific models

The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and voxelized patient data. To accomplish this we have modified a general purpose Monte Carlo transport code (MCNP4B) to simulate the CT x-ray source and movement, and then to calculate absorbed radiation dose in desired objects. The movement of the source in either axial or spiral modes was modelled explicitly while the CT system components were modelled using published information about x-ray spectra as well as information provided by the manufacturer. Simulations were performed for single axial scans using the head and body computed tomography dose index (CTDI) polymethylmethacrylate phantoms at both central and peripheral positions for all available beam energies and slice thicknesses. For comparison, corresponding physical measurements of CTDI in phantom were made with an ion chamber. To obtain absolute dose values, simulations and measurements were performed in air at the scanner isocentre for each beam energy. To extend the verification, the CT scanner model was applied to the MIRD V model and compared with published results using similar technical factors. After verification of the model, the generalized source was simulated and applied to voxelized models of patient anatomy. The simulated and measured absolute dose data in phantom agreed to within 2% for the head phantom and within 4% for the body phantom at 120 and 140 kVp; this extends to 8% for the head and 9% for the body phantom across all available beam energies and positions. For the head phantom, the simulated and measured absolute dose data agree to within 2% across all slice thicknesses at 120 kVp. Our results in the MIRD phantom agree within 11% of all the different organ dose values published by the UK's ImPACT group for a scan using an equivalent scanner, kVp, collimation, pitch and mAs. The CT source model was shown to calculate both a relative and absolute radiation dose distribution throughout the entire volume in a patient-specific matrix geometry. Results of initial testing are promising and application to patient models was shown to be feasible.

The effect of melatonin against oxidative damage during total-body irradiation in rats

Melatonin has been reported to participate in the regulation of a number of important physiological and pathological processes. Melatonin, which is a powerful endogenous antioxidant, may play a role in the prevention of oxidative damage. The aim of this study was to investigate the effect of pretreatment with melatonin (5 mg kg(-1) and 10 mg kg(-1)) on gamma-radiation-induced oxidative damage in plasma and erythrocytes after total-body irradiation with a single dose of 5 Gy. Total-body irradiation resulted in a significant increase in plasma and erythrocyte MDA levels. Melatonin alone increased the levels of SOD and GSH-Px. Erythrocyte and plasma MDA levels in irradiated rats that were pretreated with melatonin (5 or 10 mg kg(-1)) were significantly lower than those in rats that were not pretreated. There was no significant difference between the effects of 5 and 10 mg kg(-1) on plasma MDA activities and CAT activities. However, erythrocyte MDA levels showed a dose-dependent decrease, while GSH-Px activities increased with dose. Our study suggests that melatonin administered prior to irradiation may protect against the damage produced by radiation by the up-regulation of antioxidant enzymes and by scavenging free radicals generated by ionizing radiation.

Radioprotection effect of low level preirradiation on mammals: modeling and experimental investigations

This paper is devoted to experimental and theoretical studies of low level preirradiation effects on radiosensitivity of mammals. It is shown experimentally that a priming exposure to a low dose can induce radioresistance in mice in two (early and late) periods after preirradiation. The manifestation of such effects is reduced mortality of preexposed specimens after challenge acute irradiation, the reason of the animal death being the hematopoietic subsyndrome of the acute radiation syndrome. Therefore, proceeding from the radiobiological concept of critical system, the theoretical investigation of the influence of preirradiation on mammalian radiosensitivity is conducted by making use of the mathematical models of the vital body system, hematopoiesis. Modeling results obtained make it possible to elucidate the mechanisms of the radioprotection effect of low level priming irradiation on mammals. Specifically, the state of acquired radioresistance in mice is caused by reduced radiosensitivity of lymphopoietic and thrombocytopoietic systems in the early period and by reduced radiosensitivity of granulocytopoietic system, which is accompanied by slightly reduced or close to the normal level radiosensitivity of lymphopoietic system, in the late period after preirradiation. In turn, reduced radiosensitivity of above-noted hematopoietic lines is the consequence of hypercompensation of radiation damages of certain cell pools during the recovering processes running in these systems after priming irradiation. It is important to emphasize that the evaluations of the duration of the early and late periods of postirradiation radioresistance in mice, carried out on the basis of the modeling and experimental investigations, practically coincide. All this demonstrates the effectiveness of joint modeling and experimental investigations of such complicated radiobiological problems as acquired radioresistance.

The accuracy of in vivo dose measurements during Cobalt-60 total body irradiation

The purpose of this study was to check the agreement between the doses measured during total body irradiation and those previously calculated. The irradiation was performed with the use of lateral and anterior-posterior fields. The lungs were shielded during the anterior-posterior fields only when followed by an electron boost applied to the thorax wall. A cobalt-60 source was used in eight fractions on four consecutive days. Thermoluminscent, semiconductor detectors and ionisation chambers were used for in vivo measurements at several reference points on the body. The agreement between the calculated and measured doses was tested at the p=0.05 level with the use of a Student's test for a group of thirty patients.

Safety and outcome after fludarabine-thiotepa-TBI conditioning for allogeneic transplantation: a prospective study of 30 patients with hematologic malignancies

Fludarabine, thiotepa and total body irradiation (TBI) has been used as conditioning in haplo-identical transplantation. We studied this conditioning regimen in adults undergoing matched sibling transplantation and alternative donor transplantation. A total of 30 consecutive patients underwent matched related, haplo-identical related or matched unrelated donor transplantation with fludarabine, thiotepa and TBI conditioning. All but four had advanced hematologic malignancies. For haplo-identical transplant, ATG was added to the regimen. All patients received peripheral blood stem cells; these were T-cell depleted for 2-antigen or 3-antigen mismatched related transplantation. Additional graft-versus-host disease prophylaxis consisted of tacrolimus and mini-methotrexate. One recipient of haplo-identical transplant failed to engraft; all other evaluable patients had prompt engraftment. Four patients died of regimen-related toxicity. In all, 14 additional patients died of regimen-related causes including four from failure to thrive with persistent thrombocytopenia and four from delayed pulmonary toxicity. Six patients relapsed. Progression-free survival at 12 months was 47% (90% CI: 25-69%) for recipients of HLA-identical sibling transplants and 30% (90% CI: 14-46%) for all patients. Five of six long-term survivors have extensive chronic GVHD. As a result of the delayed complications and a relatively high recurrence rate, we abandoned this regimen.

Effect of total body irradiation dose escalation on outcome following T-cell-depleted allogeneic bone marrow transplantation

Prior studies of non-T-cell-depleted (TCD) transplantation have demonstrated a reduction in relapse in patients receiving escalated doses of TBI; however, overall survival in these studies was not significantly improved due to increased treatment-related toxicity seen at the higher doses of irradiation. Toxicity was in part related to an increased incidence of GVHD. Because T-cell depletion of donor bone marrow reduces the incidence of GVHD and other treatment-related complications after allogeneic bone marrow transplantation, it was postulated that TBI dose may be safely escalated in this setting and may decrease the risk of relapse following TCD BMT. Herein, we report the results of a trial assessing the safety and impact of escalated doses of TBI after TCD BMT. Two hundred adults with hematologic malignancies were treated in consecutive cohorts defined by increasing doses of TBI (1400, 1480, and 1560 cGy) in combination with cyclophosphamide. In vitro T-cell depletion using anti-CD6 monoclonal antibody was used for GVHD prophylaxis. The incidence of grade II or greater acute GVHD in patients receiving 1560 cGy (36%) was significantly higher than in patients receiving 1400 cGy (18%) (P = .04) or 1480 cGy (13%) (P = .01). Two-year treatment-related mortality was significantly higher in patients who received 1560 cGy of TBI (33%) than in those who received 1400 cGy (20%) (P = .04) or 1480 cGy (19%) (P = .05). The increased dose of TBI did not reduce the rates of relapse, with the estimated 2-year risk of relapse being 24% (1400 cGy), 24% (1480 cGy), and 31% (1560 cGy) for the 3 cohorts of patients. Overall survival at 2 years was inferior for patients receiving 1560 cGy of TBI (36%) compared with those who received 1400 cGy (55%) or 1480 cGy (58%) (P = .01). We conclude that dose escalation of TBI is associated with increased GVHD and inferior survival following TCD BMT. Future efforts to reduce the risk of relapse after TCD BMT should focus on immunologic methods to induce the graft-versus-leukemia effect after BMT rather than intensification of the ablative regimen by escalation of irradiation dose.

Allogeneic bone marrow transplantation for children with histiocytic disorders: use of TBI and omission of etoposide in the conditioning regimen

The histiocytoses are rare disorders of antigen-processing phagocytic or antigen-presenting cells. Allogeneic bone marrow transplantation (BMT) can be curative of these disorders. We report a series of five children with Langerhans cell histiocytosis (n=2) or hemophagocytic lymphohistiocytosis (n=3), who received allogeneic BMT with a total body irradiation (TBI)-containing regimen (TBI, cytarabine, and cyclophosphamide) at our institution between 1995 and 2000. One of these patients received busulfan, cyclophosphamide, and etoposide for the first of two BMTs. All grafts except one (a matched sibling-donor graft) were T-cell-depleted grafts from unrelated donors. All received cyclosporine graft-versus-host disease (GvHD) prophylaxis; the recipient of the matched sibling graft also received methotrexate. Three patients engrafted at a median of 24 days after transplantation. The patient who did not receive TBI experienced primary graft failure and recurrent disease. After the TBI-containing conditioning regimen was given, a second transplant engrafted on day +17. One patient with concurrent myelodysplastic syndrome died of toxicity on day +33 without evidence of engraftment. No acute or chronic GvHD was observed. Four patients survive disease-free, a median of 63 months after transplantation, all with Lansky performance scores of 100. We conclude that a conditioning regimen containing TBI but not etoposide is effective in allogeneic BMT for children with histiocytic diseases.

Eye shielding during total body irradiation for bone marrow transplantation in children transplanted for a hematological disorder: risks and benefits

This is a retrospective analysis of 188 children who underwent total body irradiation (TBI) in one or two fractions before bone marrow transplantation (BMT) for a hematological disorder. While 139 children had eye shielding during TBI to decrease cataract formation, 49 did not. The blocks used for shielding caused cylindrical areas of decreased dose intensity in the brain. The aim of the study was to determine if there was an increased risk of relapse in the eyes or in the CNS after shielding of the eyes. The probability and severity of cataract formation with and without shielding were also evaluated. None of the 49 children without shielding had a relapse in their eyes or in the CNS after BMT. Of the children with shielding, none had a relapse in the eyes but two of the 139 (1.4%) had a CNS relapse. The incidence of cataracts without shielding was 90% (19 of 21 evaluable patients), while with shielding it was 31% (20 of 64). Severe cataracts were present in eight of 21 (38%) patients without and two of 64 (3%) patients with shielding. The probability of staying cataract free for at least five years was 0.77 with and 0.33 without shielding, at 8 years it was 0.53 and 0.24 respectively. The relative risk of developing a cataract without shielding vs shielding was three (95% CI=1.5; 5.9). It appears that the incidence of relapse in the eyes and CNS is not increased when the eyes are shielded during TBI. Shielding increased the latency time of cataract formation and decreased the severity of cataracts.

Prognostic value of cyclic GMP in patients undergoing allogeneic bone marrow transplantation after conditioning with total body irradiation

This study was performed to investigate whether measurement of cyclic GMP (cGMP), a marker for nitric oxide production, before and after allogeneic bone marrow transplantation (BMT) with total body irradiation (TBI) conditioning was of prognostic value. cGMP levels were monitored in 23 consecutive patients who received TBI as conditioning for BMT, and were compared with the outcome. cGMP became positive during the aplastic phase after BMT in 12 patients. In nine of these 12 patients, cGMP level decreased during the recovery phase. Eight of the nine patients survived, one dying after relapse. In three other patients, the cGMP level continued to increase even during the recovery phase and they died of severe complications. cGMP became positive on day 0 of BMT and during the leukocyte recovery phase after BMT in two and seven of the 23 patients, respectively. Subsequently, all patients died of severe complications. The two patients who were negative for cGMP both before and after BMT survived without complications. These results suggest that monitoring cGMP from early after BMT may be useful for predicting outcome and that it may be a useful prognostic marker.

A prospective, randomized trial for the prevention of mucositis in patients undergoing hematopoietic stem cell transplantation

Oral mucositis is a complication common to many cancer therapies and produces considerable pain and morbidity. The present study reports a double-blind, prospective, randomized clinical trial testing the efficacy of a calcium phosphate mouth rinse (Caphosol) with fluoride treatments vs a standard regimen of fluoride rinsing and placebo tray treatments in 95 patients undergoing hematopoietic stem cell transplantation (HSCT). The days and severity of mucositis were prospectively evaluated. There were statistically significant decreases in days of mucositis (3.72 vs 7.22 P=0.001), duration of pain (2.86 vs 7.67, P=0.0001), dose of morphine (34.54 mg vs 122.78 mg), days of morphine (1.26 vs 4.02, P=0.0001) and days to the onset of engraftment ANC (absolute neurotrophil count)>200 mm(3) (11.12 vs 12.56) in the Caphosol and fluoride treatment group vs fluoride-rinse group, respectively. Caphosol, a neutral, supersaturated, Ca(2+)/PO(4)(3-) mouth rinse, used in combination with topical fluoride treatments, is superior to fluoride rinse alone in reducing the frequency, intensity and duration of oral mucositis in patients undergoing HSCT.

Specific absorption rate and temperature elevation in a subject exposed in the far-field of radio-frequency sources operating in the 10-900-MHz range

The exposure of a subject in the far field of radiofrequency sources operating in the 10-900-MHz range has been studied. The electromagnetic field inside an anatomical heterogeneous model of the human body has been computed by using the finite-difference time-domain method; the corresponding temperature increase has been evaluated through an explicit finite-difference formulation of the bio-heat equation. The thermal model used, which takes into account the thermoregulatory system of the human body, has been validated through a comparison with experimental data. The results show that the peak specific absorption rate (SAR) as averaged over 10 g has about a 25-fold increase in the trunk and a 50-fold increase in the limbs with respect to the whole body averaged SAR (SARWB). The peak SAR as averaged over 1 g, instead, has a 30- to 60-fold increase in the trunk, and up to 135-fold increase in the ankles, with respect to SARWB. With reference to temperature increases, at the body resonance frequency of 40 MHz, for the ICNIRP incident power density maximum permissible value, a temperature increase of about 0.7 degrees C is obtained in the ankles muscle. The presence of the thermoregulatory system strongly limits temperature elevations, particularly in the body core.

Anti-pressor effects of whole body exposure to static magnetic field on pharmacologically induced hypertension in conscious rabbits

Acute effects of whole body exposure to static magnetic field (SMF) on pharmacologically induced hypertension in a conscious rabbit were evaluated. Hypertensive and vasoconstrictive actions were induced by norepinephrine (NE) or a nonselective nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-l-arginine methyl ester (l-NAME). The hemodynamics in a central artery of the ear lobe was measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, blood pressure (BP) changes in a central artery, contralateral to that of the MPPG measured ear lobe, were monitored. Magnetic flux densities were 5.5 mT (Bmax), the magnetic gradient peaked in the throat at the level of approximately 0.09 mT/mm, and the duration of exposure was 30 min. The results demonstrated that under normal physiological conditions without treatment of pharmacological agents, there were no statistically significant differences in the hemodynamics and BP changes between the sham and the SMF exposure alone. Under pharmacologically induced hypertensive conditions, the whole body exposure to nonuniform SMF with peak magnetic gradient in the carotid sinus baroreceptor significantly attenuated the vasoconstriction and suppressed the elevation of BPs. These findings suggest that antipressor effects of the SMF on the hemodynamics under NE or l-NAME induced high vascular tone might be, in part, dependent on modulation of NE mediated response in conjunction with alteration in NOS activity, thereby modulating BPs.

Human exposure assessment in the near field of GSM base-station antennas using a hybrid finite element/method of moments technique

A hybrid finite-element method (FEM)/method of moments (MoM) technique is employed for specific absorption rate (SAR) calculations in a human phantom in the near field of a typical group special mobile (GSM) base-station antenna. The MoM is used to model the metallic surfaces and wires of the base-station antenna, and the FEM is used to model the heterogeneous human phantom. The advantages of each of these frequency domain techniques are, thus, exploited, leading to a highly efficient and robust numerical method for addressing this type of bioelectromagnetic problem. The basic mathematical formulation of the hybrid technique is presented. This is followed by a discussion of important implementation details-in particular, the linear algebra routines for sparse, complex FEM matrices combined with dense MoM matrices. The implementation is validated by comparing results to MoM (surface equivalence principle implementation) and finite-difference time-domain (FDTD) solutions of human exposure problems. A comparison of the computational efficiency of the different techniques is presented. The FEM/MoM implementation is then used for whole-body and critical-organ SAR calculations in a phantom at different positions in the near field of a base-station antenna. This problem cannot, in general, be solved using the MoM or FDTD due to computational limitations. This paper shows that the specific hybrid FEM/MoM implementation is an efficient numerical tool for accurate assessment of human exposure in the near field of base-station antennas.

Age-dependent protection quantities for external neutron irradiation

Based on the recommendations issued by the International Commission on Radiological Protection (ICRP), equivalent doses and effective doses for different ages are obtained for external neutron sources. The calculations at 28 neutron energies from 1 x 10(-9) MeV to 20 MeV are carried out for six irradiation geometries: AP, PA, RLAT, LLAT, ROT and ISO. An age-dependent anthropomorphic mathematical phantom series of six age groups: newborn, 1, 5, 10, 15 years old and adult is used with the Monte Carlo computer code MCNP for the dose evaluations. The results for adults are compared with those in ICRP Publication 74 and are in good agreement. At low energies the effective doses increase as the phantom age increases, but at high energics they decrease with increasing age for the AP, PA, ROT and ISO irradiation geometries. In the whole energy region the effective doses decrease as the phantom age increases for the RLAT and LLAT irradiation geometries. The age-dependent equivalent doses behave similarly to the effective doses, with some exceptions caused by the influence of the organ position.

[Carcinogenic effects of single total-body irradiation with accelerated charged particles and gamma rays]

The study deals with the frequency of tumorigenesis in the endocrine glands, skin, soft tissues and internal organs of sexually mature female rats, exposed to accelerated charged particles with low LPE, such components of cosmic radiation as 645 MeV and 9 GeV protons and 4 GeV/nuclon ions of helium. The experiment continued until the animals' natural death. We established a high frequency of endocrine and uterine tumors and a comparatively wide range of localizations in rats which had received sufficient doses of gamma radiation. There were no intestinal or renal tumors, while very few tumors of the skin and soft tissues were detected in unexposed animals.