[An evaluation of the effect of magnetic-laser therapy on external respiratory function in complicated forms of acute pneumonia in children]

The authors studied the effects of magnetic laser therapy (MLT) on external respiration, blood transport of gas and clinical course of acute destructive pneumonia in children aged 1-12 years. It was established that energy of infrared laser combined with magnetic field reduces the severity of acute respiratory insufficiency, treatment course, prevents destructive complications in children with infiltrative acute destructive pneumonia.

[The effect of low-energy laser radiation in the infrared spectrum on bronchial patency in children with bronchial asthma]

Pulsed and continuous-wave low-energy infrared laser radiations were compared for effects on bronchial patency in 139 children with bronchial asthma aged 4-15 years. The pulsed regimen improved patency of the main bronchi in atopic asthma attacks and after them, while continuous-wave regimen improved patency of the peripheral bronchi in bacterial asthma in attack-free period.

[The effect of chronic irradiation with intermittent unmodulated microwaves on the functional status of the rabbit]

A group of 10 chinchilla male rabbits were exposed to 800 MHz alternative microwave fields. The data obtained revealed changes in the EEG, ECG and respiration in only 2 rabbits after 5-7 experiments.

[Evaluation of changes in electrophysiological and hormonal parameters in rabbits resulting from short-term low-intensity ultra-high-frequency irradiation]

The paper is devoted to study of the influence of short-term low-level microwave irradiation (6GHz, modulation 2 Hz, average intensity 0.015 mW/cm2, exposure time 50 min) on some electrophysiological and hormonal parameters in rabbits. No reliable changes in cardiac and respiratory rhythms, electromyogram intensity as well as cortisol, testosterone, insulin and thyroxine level in rabbits' blood were found.

Repair rate in mouse lung after clinically relevant radiation doses per fraction

Data published previously have shown that repair of sublethal damage in mouse lung proceeds with two significantly different repair half-times of 0.4 h and 4.0 h and that the fast component has approximately four times more weight than the slow component. None of these data, however, were obtained after small dose fractions similar to those used in clinical radiotherapy. The purpose of the experiments presented here was to determine the half-time of the fast component only of repair in mouse lung after doses per fraction of 2.0 Gy. We irradiated the whole thoraces of mice with six equal doses of 2.09 Gy given at intervals ranging from 0 to 45 min. The dose was topped up 24 h later by a range of single doses designed to bring the response, i.e. breathing rate and death from pneumonitis, into the observable range. Data on breathing rate were converted into quantal response data. All data were analyzed by the linear-quadratic model that contains two rates of repair (H.D. Thames et al., Radiother, Oncol. 15, 49-53, 1989). The data showed that the repair rate is very rapid, giving a t1/2 ranging from 0.25 to 0.75 h for breathing rate and mortality, in agreement with our data published previously for higher dose fractions. There were no differences between the t1/2's obtained from the two assays of damage. These data indicate that the half-time of the fast component of repair in mouse lung is approximately 0.4 h after clinically relevant dose fractions.

Dose-effect relations for local functional and structural changes of the lung after irradiation for malignant lymphoma

PURPOSE

To estimate the dose-effect relations for local functional (ventilation and perfusion) and structural (density) changes of the lung, 3-4 months after irradiation.

METHODS

Twenty-five patients with malignant lymphoma were irradiated with a (modified) mantle field to an average dose of 38 Gy, given in 21 fractions. Single photon emission computed tomography (SPECT) ventilation (V) and perfusion (Q) scans, and CT scans were performed before and 3-4 months after radiation treatment. The three-dimensional dose distribution was calculated using the CT data. After correlation of SPECT and CT data sets, the average post-treatment value of V, Q and lung density per voxel was calculated relative to the pre-treatment value, per dose interval of 4 Gy. Subsequently, the dose-effect relations in each patient were normalized to the average value per voxel in the dose interval of 0-12 Gy. In addition, in each dose interval of 4 Gy the fraction of patients with changes larger than 20% was calculated for all three parameters. The dose-effect relations for perfusion and ventilation normalized to the low-dose regions, and the dose-incidence curves for the fraction of patients with changes larger than 20% were fitted for all three parameters, using a logistic model.

RESULTS

Marked changes in the distribution of V and Q were found after irradiation. Prior to normalization to the low-dose regions, a change in V and Q was found in most patients in the dose interval of 0-12 Gy, varying from an increase of 37% to a decrease of 10%, which was followed by a decreasing trend at higher doses. The increase in the low-dose regions indicated a redistribution phenomenon, the magnitude of which was dependent of the irradiated volume. The logistic fit of the dose-effect relations for Q and V, normalized to the low-dose regions, resulted in values for D50 of 51 Gy and 54 Gy (given in 21 fractions on average), respectively, and for the steepness parameter k of 4.2 and 4.0, respectively. The logistic fit for the dose-incidence curves for Q, V and lung density resulted in values for D50 and k of 38 Gy, 37 Gy, 44 Gy and 10.3, 7.8 and 9.4, respectively.

CONCLUSIONS

With the combined use of SPECT and CT scans, we have obtained dose-effect relations for local functional and structural damage in the lung, 3-4 months after irradiation.

[Intersystemic functional integration under the action on the body of electromagnetic factors]

Frequency zones of the brain electrical activity, heart rate and respiration were studied through certain parameters characterised by individual asymmetry and low but stable intersystemic integration. Chronic electromagnetic irradiation reduced a resistance against an emotional stress as manifested in a "decay" of individual spatial-temporal infrastructure of informational parameters of the EEG, heart rate and respiration.

Different immobilization procedures during irradiation influence the estimation of alpha/beta ratios in mouse lip mucosa

In previous experiments an anaesthetic gas mixture of enflurane (Ethrane, Abbott, Belgium) and oxygen has been used in our department to position mice for local irradiation. The development of a new immobilization method allowed the investigation of possible dose modifying effects of enflurane with different gases as carrier on the radiation response of mouse lip mucosa. The effect of different immobilization procedures on single dose and fractionated irradiations was examined. The experiments were compared on the basis of the dose associated with 50% incidence of lower lip desquamation (ED50 +/- 95% CI). When mice were breathing air the ED50 value following single dose irradiation was 20.0 (19.6 to 20.5) Gy. For mice receiving an anaesthetic gas mixture of enflurane and oxygen the ED50 was decreased significantly to 17.5 (17.2 to 17.8) Gy, indicating a sensitizing effect of the anaesthetic mixture by a factor of 1.14. The impact of different experimental set-ups on the fractionation sensitivity has been assessed. In order to estimate alpha/beta ratios in different treatment conditions two and ten fraction experiments were performed, additionally to the single dose irradiations. Dose modification factors were 1.09 for two fractions and 0.97 for the ten fraction experiment. This varying dose modification leads to a pronounced shift in alpha/beta ratios (estimated by "direct analysis" and graphically illustrated with a Fe-plot). For air breathing animals an alpha/beta ratio of 16.4 (14.5 to 18.9) Gy was estimated by direct analysis, whereas for the enflurane/oxygen anaesthesia 8.7 (7.3 to 10.2) Gy were calculated. Both these data sets were adequately described with the linear-quadratic formalism, as was shown with Tucker's analysis. The sensitizing effect of oxygen alone in single dose irradiations (DMF: 1.07) suggests moderate physiological hypoxia in mouse lip mucosa. The present data emphasize the effect of different immobilization procedures on the estimation of alpha/beta ratios, especially when large fraction sizes are involved. Data from experiments involving large fraction sizes should be avoided in the estimation of repair parameters. Further experimental work has to be carried out to elucidate the possible dose modifying effects of anaesthetic agents in clinical practice, e.g. for infants and for patients undergoing intraoperative radiotherapy.

Pulmonary changes induced by combined mouse beta-interferon (rMuIFN-beta) and irradiation in normal mice--toxic versus protective effects

This study in normal mice was undertaken to investigate possible enhancement of pulmonary toxicity by interferon-beta (IFN-beta) combined with single doses of irradiation. A pharmacokinetic study preceded the toxicity study to determine the optimal route and timing of IFN administration. Graded single doses of radiation were combined with graded doses of IFN. Pulmonary toxicity was determined using endpoints of alveolar surfactant and procollagen in lung lavage fluid at 7 days, breathing frequency, lethality and histology. Increased lethality was seen when IFN was combined with irradiation at 12.5 Gy vs. irradiation alone. This occurred between 20 and 30 weeks post treatment with no increased breathing frequency or surfactant release, suggesting independent mechanisms of injury. Increased breathing frequency after 40 weeks, usually associated with fibrosis, was less pronounced for IFN treated vs. irradiation only controls. Ultrastructural studies at 72 weeks suggest reduced fibrosis in lungs of IFN treated vs. irradiation only controls. Supporting this was the finding that Procollagen III, a biosynthetic precursor of collagen, was increased in the lavage fluid at 7 days for all radiation doses but decreased with the addition of IFN at 12.5 and 15 Gy. Interferons can act either as sensitizers or radioprotectors, depending on the biological system and type of interferon. Our study suggests that while IFN-beta may increase the acute effects of radiation in the mouse lung, some protection from radiation-induced fibrosis, possibly related to alteration of immune mechanisms, may exist.

Mouse hemithoracic irradiation and its interaction with cytotoxic drugs

Irradiation of the mouse right or left hemithorax at 14 or 18 Gy produced a dose-dependent rise in breathing rate 16 weeks after irradiation without significant mortality. The measurement of breathing rate changes following right hemithoracic irradiation combined with the maximally tolerated dose of cytotoxic drugs was assessed as a method for qualitatively detecting drug-irradiation interactions which either exacerbate pneumonitis or alter its time course. Cyclophosphamide at 100 mg/kg accentuated and accelerated the rise in breathing rate, culminating in early mortality. BCNU 30 mg/kg delayed the appearance of the radiation response. Busulphan 30 mg/kg appeared to be radioprotective, but this was shown to be due to the DMSO-containing vehicle. Doxorubicin 6 mg/kg had no effect when combined with right or left hemithoracic irradiation. Carboplatin 100 mg/kg, vindesine 4 mg/kg and vinblastine 4 mg/kg had no substantial effect upon the changes in breathing rate.

Effect of radiation on pulmonary functions in patients with breast cancer

There is no systematic study available from our country regarding pulmonary function tests in patients of breast cancer who receive postoperative radiotherapy. Therefore, we planned a prospective study to find out the effect of radiation on pulmonary functions in patients with breast cancer; who had undergone surgery in the form of simple mastectomy and axillary clearance. Transient radiological changes were seen in two cases and one patient had fibrosis at 9 months.

Cardiovascular changes in unanesthetized and ketamine-anesthetized Sprague-Dawley rats exposed to 2.8-GHz radiofrequency radiation

Sprague-Dawley rats were exposed to 2.8-GHz radiofrequency radiation, first while unanesthetized and then while anesthetized with ketamine (150 mg/kg.I.M.). Irradiation at a power density of 60 mW/cm2 (whole-body average specific absorption rate of approximately 14 W/kg) was conducted for sufficient duration to increase colonic temperature from 38.5 to 39.5 degrees C. The time required for the temperature increase was significantly longer in the anesthetized state. During irradiation, heart rate increased significantly both with and without anesthesia, while mean arterial blood pressure increased only when the rats were unanesthetized. The heart rate increase in the anesthetized state contrasts with a lack of change in a previous study of Fischer rats. This difference between anesthetized Sprague-Dawley and Fischer rats should be considered when comparing cardiovascular data obtained from these two strains of rats.

Field orientation effects during 5.6-GHz radiofrequency irradiation of rats

Ketamine-anesthetized Sprague-Dawley rats were exposed in E and H orientations (long axis parallel to electric and magnetic fields, respectively) to far-field 5.6-GHz continuous-wave radio-frequency radiation (RFR). Power densities were used that resulted in equivalent whole-body average specific absorption rates of 14 W/kg in both orientations (90 mW/cm2 for E and 66 mW/cm2 for H). Irradiation was conducted to increase colonic temperature by 1 degree C (from 38.5 to 39.5 degrees C). During experimentation, arterial blood pressure and respiratory rate and colonic, tympanic, left and right subcutaneous (sides toward and away from RFR source), and tail temperatures were continuously recorded. Results showed no significant difference in the times required to cause a 1 degree C increase or to recover to the initial temperature when irradiation was stopped. Significant differences between E- and H-orientation exposure were seen in the patterns of localized heating. The tail and left subcutaneous temperature increases were significantly greater during E-orientation exposure, the tympanic site showed no difference, and the right subcutaneous temperature increase was significantly greater during H-orientation exposure. Under both exposure conditions, heart rate and mean arterial blood pressure significantly increased during irradiation; however, there were no significant differences between E and H orientation responses. These findings at 5.6 GHz are in contrast to the significant cardiovascular response differences between E- and H-orientation exposure noted during a previous study of irradiation at 2.45 GHz.

Thermal and physiologic responses to 1200-MHz radiofrequency radiation: differences between exposure in E and H orientation

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 1200-MHz continuous wave radiofrequency radiation in both E and H orientations (long axis of animal parallel to electric or magnetic field, respectively). Power densities were used that resulted in equivalent whole-body specific absorption rates of approximately 8 W/kg in both orientations (20 mW/cm2 for E and 45 mW/cm2 for H). Exposure was conducted to repeatedly increase colonic temperature from 38.5 to 39.5 degrees C in both orientations in the same animal. Irradiation in E orientation resulted in greater colonic, tympanic, left subcutaneous (side toward antenna), and tail heating. The results indicated a more uniform distribution of heat than that which occurred in previous experiments of 2450-MHz irradiation in E and H orientation. A lack of significant differences in blood pressure and heart rate responses between exposures in the two orientations in this study suggest that greater peripheral heating, as was seen in the earlier study of 2450 MHz, is necessary for these differences to occur.

Biological effects of inhaled 239PuO2 in rats with pre-existing pulmonary emphysema

The modifying effects of pre-existing pulmonary emphysema on the deposition, distribution, retention and effects of inhaled 239PuO2 in the rat were investigated. The presence of emphysema in the rats was documented by morphometric and respiratory function measurements. For rats exposed to similar airborne concentrations of 239PuO2, initial lung burdens of 239Pu per kg body mass were lower in rats with emphysema than in those without emphysema; however, the retention of 239Pu over time was similar in both groups. The distribution of 239Pu particles in the lungs of rats with emphysema tended to be more random than in the lungs of control rats. The life span, and incidences of non-neoplastic and neoplastic lesions in the lung, and risk of lung tumours per unit of alpha dose to the lungs in the rats with emphysema were similar to or less than in the control rats, when groups with similar initial lung burdens of 239Pu were compared. The results of this study suggest that humans with uncomplicated pulmonary emphysema are not necessarily more sensitive to the carcinogenic effects of inhaled 239PuO2 than individuals with normal lungs.

Physiologic consequences of local heart irradiation in rats

Noninvasive methods have been used to study the long-term cardiovascular and pulmonary functional changes at rest and after exercise in adult rats following local heart irradiation with single x-ray doses of 15, 17.5 or 20 Gy, and in non-irradiated control animals. Rats that had undergone a chronic exercise program were compared with untrained cohorts. The earliest dysfunction detected was an increased respiratory rate (f) at 10 weeks after irradiation in the highest dose group. In contrast, both telemetric heart-rate (HR) and rhythm and indirect systolic blood pressure measurements performed at rest only revealed changes starting at 43 weeks after irradiation with 20 Gy, up to which point the rats showed no clinical signs of heart failure. However, the number of minutes required for the recovery of the HR to pre-exercise levels following the implementation of a standardized exercise challenge was elevated in untrained rats compared with their trained cohorts at 18 weeks after irradiation with 20 Gy. Increases in recovery times were required in the two lowest dose groups, starting at 26 weeks after irradiation. It was concluded that the reserve capacity of the cardiopulmonary system masks functional decrements at rest for many months following local heart irradiation, necessitating the use of techniques which reveal reductions in reserve capacities. Further, the influence of local irradiation to the heart and lungs deserves closer scrutiny due to mutual interactions.

Thermal and physiological changes in rats exposed to CW and pulsed 2.8 GHz radiofrequency radiation in E and H orientations

Ketamine-anesthetized Sprague-Dawley rats were exposed in both E and H orientations to far-field 2.8 GHz continuous-wave (CW) and pulsed (0.5 microseconds, 500 pps) radiofrequency radiation (RFR) at equivalent whole-body average specific absorption rates (SAR) of approximately 14 W/kg. Intermittent irradiation was performed in all four exposure conditions, in the same animal, to repeatedly increase colonic temperature from 38.5 to 39.5 degrees C. Tympanic, subcutaneous (sides toward and away from RF sources), colonic, and tail temperatures, electrocardiogram, arterial blood pressure, and respiratory rate were continuously recorded. The results revealed no significant difference between the thermal effects of CW and pulsed RFR exposure. The results did show significant differences between the thermal effects of E- and H-orientation exposure. H-orientation irradiation produced significantly faster colonic temperature increases and, with the exception of the tail, produced significantly greater localized heating in the anesthetized rat, and higher local SAR in rat carcasses than did E-orientation exposure. Under all exposure conditions, heart rate and blood pressure increased significantly during irradiation and returned to baseline when exposure was discontinued. Respiratory rate remained unchanged during irradiation. There were no significant differences between the effects of E- and H-orientation exposure, or between CW and pulsed irradiation, upon heart rate, blood pressure, and respiratory rate.

[Effect of dipidolor on hemodynamics and respiration in rats after exposure to gamma-radiation and cytostatics]

It was shown in experiments on anesthetized rats that intramuscular administration of dipidolor (5 mg/kg) failed to exert any effect on the functioning of the cardiovascular and respiratory systems of the animals which previously had been irradiated with the dose of 50 Gy or given intravenous injections of platidyam (5 mg/kg) or cyclophosphane (50 mg/kg).

[External respiratory function during the combined treatment of breast cancer with the 254Cf irradiation of the parasternal lymph nodes]

External respiratory function was investigated in 92 breast cancer patients before and after combined therapy. Changes in external respiratory function of the obstructive and restrictive type were observed only in the patients who had been subjected to preoperative gamma teletherapy, radical mastectomy and subsequent contact irradiation of the parasternal lymph nodes by administering 252Cf into the thoracic artery (vein). These changes were determined by gamma teletherapy. The absence of disturbed indicators of gaseous exchange and acid-alkali balance of the capillary blood suggested a compensatory type of changes in external respiratory function.

The use of CT densitometry in the assessment of radiation-induced damage to the rat lung: a comparison with other endpoints

Changes in rat lung following irradiation have been assessed on the basis of survival, histopathology, function (breathing rate assay), and density changes measured by computed tomography (CT) scanning. CT densitometry is a non-invasive procedure which may be used without modification to assess lung damage in experimental animals and in man. An increase in the breathing rate is seen following irradiation of the thorax, the time of onset and severity of which are dose dependent and correlate with histopathological changes occurring at the same time. Lung density changes occurring after irradiation are more complex. For the lowest dose used (10.75 Gy) no density increase was observed and in fact density decreased with time after irradiation to a slightly greater extent than in non-irradiated controls. A post-irradiation increase in lung density was seen for rats given 13.0 Gy, but values fluctuated with maxima at 50 and 225 days after irradiation. Higher radiation doses (14.5, 16.0 Gy) were followed by a transient decrease in density before a dose-related density increase was observed. Density averaged over the whole lung proved to be a sub-optimal index of radiation-induced lung damage because of the focal nature of radiation-induced lung lesions and because of the apparently anomalous changes in post-irradiation damage which are observed. Further studies are being made to determine if regional density values will provide a more sensitive index.

The effect of thoracic irradiation for cancer of the breast on ventilation, perfusion and pulmonary permeability. A one-year follow-up

Regional and overall lung function was studied in 14 women during a one-year follow-up after postmastectomy irradiation for cancer of the breast. The dose was 40 Gy in the chest wall and 20-40 Gy in the apex of the lung. Immediately after irradiation there was a slight increase in pulmonary clearance of 99TCm-DTPA compared to baseline values. This increase, however, was not restricted to the field of irradiation. Three months after irradiation there were regional defects in the ventilation and perfusion scintigrams in 11 of the patients. At the same time there was a greater decrease in total lung capacity, vital capacity and diffusion capacity for CO than in ventilation and perfusion. One year after irradiation the lung function impairment had only insignificantly regressed. It is concluded that local lung irradiation may cause persistent regional and generalized lung function impairment. The early increase in pulmonary clearance of 99Tcm-DTPA could not be used as a predictor of subsequent lung function impairment.