Photorespiration Regulates Carbon-Nitrogen Metabolism by Magnesium Chelatase D Subunit in Rice

The growth and development of plants are dependent on the interaction between carbon and nitrogen metabolism. Essential information about the metabolic regulation of carbon-nitrogen metabolism is still lacking, such as possible interactions among nitrogen metabolism, photosynthesis, and photorespiration. This study shows that higher photorespiration consumes more CO₂ fixed by photosynthesis, making the high photosynthetic efficiency mutant fail to increase production. In order to clarify the effects of photosynthesis and photorespiration on carbon and nitrogen metabolism in high photosynthetic efficiency mutant, a yellow-green leaf mutant (ygl53) was isolated from rice (Oryza sativa L.). Its chlorophyll (Chl) content decreased, but chloroplast development was not affected. Genetic analysis demonstrated that YGL53 encodes the magnesium chelatase D subunit (ChlD). The ygl53 mutant showed an increased net assimilation rate (An) and electron transport flux efficiency and catalase (CAT) activity, and it also had a higher photorespiration rate (Pr), lower H₂O₂, and reduced nitrogen uptake efficiency (NUpE); however, there was no loss in yield. The higher activities of glutamate synthase (GOGAT) and glutamine synthetase (GS) ensure the α-ketoglutaric acid (2-OG) and ammonia (NH₃) availabilities, which are produced from photorespiration in the ygl53 mutant. These have an important function for carbon and nitrogen metabolism homeostasis in ygl53. Further analysis indicated that the energy and substances derived from carbon metabolism supplemented nitrogen metabolism in the form of photorespiration to ensure its normal development when the An of photosynthesis was increased in the ygl53 mutant with reduced NUpE.

Light respiratory processes and gross photosynthesis in two scleractinian corals

The light dependency of respiratory activity of two scleractinian corals was examined using O2 microsensors and CO2 exchange measurements. Light respiration increased strongly but asymptotically with elevated irradiance in both species. Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes. Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range. P. decussata also harboured twice as many algal symbionts and higher total protein biomass compared to P. damicornis, possibly resulting in self-shading of the symbionts and/or changes in host tissue specific light distribution. Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.

The delayed pulmonary syndrome following acute high-dose irradiation: a rhesus macaque model

Several radiation dose- and time-dependent tissue sequelae develop following acute high-dose radiation exposure. One of the recognized delayed effects of such exposures is lung injury, characterized by respiratory failure as a result of pneumonitis that may subsequently develop into lung fibrosis. Since this pulmonary subsyndrome may be associated with high morbidity and mortality, comprehensive treatment following high-dose irradiation will ideally include treatments that mitigate both the acute hematologic and gastrointestinal subsyndromes as well as the delayed pulmonary syndrome. Currently, there are no drugs approved by the Food and Drug Administration to counteract the effects of acute radiation exposure. Moreover, there are no relevant large animal models of radiation-induced lung injury that permit efficacy testing of new generation medical countermeasures in combination with medical management protocols under the FDA animal rule criteria. Herein is described a nonhuman primate model of delayed lung injury resulting from whole thorax lung irradiation. Rhesus macaques were exposed to 6 MV photon radiation over a dose range of 9.0-12.0 Gy and medical management administered according to a standardized treatment protocol. The primary endpoint was all-cause mortality at 180 d. A comparative multiparameter analysis is provided, focusing on the lethal dose response relationship characterized by a lethal dose50/180 of 10.27 Gy [9.88, 10.66] and slope of 1.112 probits per linear dose. Latency, incidence, and severity of lung injury were evaluated through clinical and radiographic parameters including respiratory rate, saturation of peripheral oxygen, corticosteroid requirements, and serial computed tomography. Gross anatomical and histological analyses were performed to assess radiation-induced injury. The model defines the dose response relationship and time course of the delayed pulmonary sequelae and consequent morbidity and mortality. Therefore, it may provide an effective platform for the efficacy testing of candidate medical countermeasures against the delayed pulmonary syndrome.

A pilot study in rhesus macaques to assess the treatment efficacy of a small molecular weight catalytic metalloporphyrin antioxidant (AEOL 10150) in mitigating radiation-induced lung damage

The objective of this pilot study was to explore whether administration of a catalytic antioxidant, AEOL 10150 (C48H56C15MnN12), could reduce radiation-induced lung injury and improve overall survival when administered after 11.5 Gy of whole thorax lung irradiation in a non-human primate model. Thirteen animals were irradiated with a single exposure of 11.5 Gy, prescribed to midplane, and delivered with 6 MV photons at a dose rate of 0.8 Gy min. Beginning at 24 h post irradiation, the AEOL 10150 cohort (n = 7) received daily subcutaneous injections of the catalytic antioxidant at a concentration of 5 mg kg for a total of 4 wk. All animals received medical management, including dexamethasone, based on clinical signs during the planned 180-d in-life phase of the study. All decedent study animals were euthanized for failure to maintain saturation of peripheral oxygen > 88% on room air. Exposure of the whole thorax to 11.5 Gy resulted in radiation-induced lung injury in all animals. AEOL 10150, as administered in this pilot study, demonstrated potential efficacy as a mitigator against fatal radiation-induced lung injury. Treatment with the drug resulted in 28.6% survival following exposure to a radiation dose that proved to be 100% fatal in the control cohort (n = 6). Computed tomography scans demonstrated less quantitative radiographic injury (pneumonitis, fibrosis, effusions) in the AEOL 10150-treated cohort at day 60 post-exposure, and AEOL 10150-treated animals required less dexamethasone support during the in-life phase of the study. Analysis of serial plasma samples suggested that AEOL 10150 treatment led to lower relative transforming growth factor-Beta-1 levels when compared with the control animals. The results of this pilot study demonstrate that treatment with AEOL 10150 results in reduced clinical, radiographic, anatomic, and molecular evidence of radiation-induced lung injury and merits further study as a medical countermeasure against radiation-induced pulmonary injury.

[Morphologic changes in mice trachea, bronchi and lungs after prolonged combined radiation and inhaled chemical exposure]

Investigations of morphology and morphometry of the breathing organs (trachea, bronchi and lungs) and immunogenesis of mice subject to a combined sequential exposure to fractionated external γ-irradiation by the total dose of 350 cGy and a mix of acetone, ethanol and acetaldehyde in MPCs for piloted spacecrafts simulating the estimated levels in crewed exploration missions were conducted. Morphologic changes in the breathing organs of animals after space missions point to immunogenesis activation and appearance of a "structural trace" as a chronic inflammation with the growth of fibrous connective tissue in tracheal, bronchial and lung walls, increase in volume fractions of glands and vessels and reduction in loose fibrous connective tissue. Formation of the fibrous connective tissue was particularly noticeable in respiratory parts of the breathing organs suggesting a high risk of long-term adverse effects.

Reduced lung dose and improved inspiration level reproducibility in visually guided DIBH compared to audio coached EIG radiotherapy for breast cancer patients

INTRODUCTION

Patients with left-sided breast cancer with lymph node involvement have routinely been treated with enhanced inspiration gating (EIG) for a decade at our institution. In a transition from EIG to deep inspiration breath hold (DIBH) we compared the two techniques with focus on target coverage, dose to organs at risk and reproducibility of the inspiration level (IL).

MATERIAL AND METHODS

Twenty-four patients were computed tomography (CT) scanned with EIG and DIBH. For DIBH we used visual feedback and for EIG audio coaching, both during scan and treatment. Treatment plans for 50 Gy over 25 fractions were calculated. Seventeen of the patients were included in the analysis of reproducibility. They were audio coached for one minute before beam-on in DIBH at nine treatment sessions. These respiration curves were analysed with average maximum IL and standard deviation (SD) for the EIG part of the respiratory signal, and mean IL and SD for the DIBH. Comparison of dosimetric and respiration parameters were performed with the Wilcoxon signed rank-sum test.

RESULTS

In DIBH, the ipsilateral lung volume increased further compared to EIG (p < 0.0004, mean increase 11%). This lead to a 9% mean reduction (p = 0.002) of the ipsilateral lung volume receiving 20 Gy (V20 Gy). We found no other significant dosimetric differences between the two methods. The reproducibility of the IL was better with the DIBH method, observed as a significantly smaller SD in most patients (p < 0.04 for 16 of 17 patients).

CONCLUSION

The DIBH method resulted in a significantly larger lung volume and lower ipsilateral lung V20 Gy compared to EIG. The IL for visually guided DIBH was more reproducible than audio-coached EIG. Based on these findings, the DIBH technique is our new breathing adaptation standard for radiotherapy of patients with left-sided breast cancer with lymph node involvement.

Determination and maintenance of DE minimis risk for migration of residual tritium (3H) from the 1969 Project Rulison nuclear test to nearby hydraulically fractured natural gas wells

The Project Rulison underground nuclear test was a proof-of-concept experiment that was conducted under the Plowshare Program in 1969 in the Williams Fork Formation of the Piceance Basin in west-central Colorado. Today, commercial production of natural gas is possible from low permeability, natural gas bearing formations like that of the Williams Fork Formation using modern hydraulic fracturing techniques. With natural gas exploration and production active in the Project Rulison area, this human health risk assessment was performed in order to add a human health perspective for site stewardship. Tritium (H) is the radionuclide of concern with respect to potential induced migration from the test cavity leading to subsequent exposure during gas-flaring activities. This analysis assumes gas flaring would occur for up to 30 d and produce atmospheric H activity concentrations either as low as 2.2 × 10 Bq m (6 × 10 pCi m) from the minimum detectable activity concentration in produced water or as high as 20.7 Bq m (560 pCi m), which equals the highest atmospheric measurement reported during gas-flaring operations conducted at the time of Project Rulison. The lifetime morbidity (fatal and nonfatal) cancer risks calculated for adults (residents and workers) and children (residents) from inhalation and dermal exposures to such activity concentrations are all below 1 × 10 and considered de minimis. The implications for monitoring production water for conforming health-protective, risk-based action levels also are examined.

Dose-modifying factor for captopril for mitigation of radiation injury to normal lung

Our goal is to develop countermeasures for pulmonary injury following unpredictable events such as radiological terrorism or nuclear accidents. We have previously demonstrated that captopril, an angiotensin converting enzyme (ACE) inhibitor, is more effective than losartan, an angiotensin type-1 receptor blocker, in mitigating radiation-pneumopathy in a relevant rodent model. In the current study we determined the dose modifying factors (DMFs) of captopril for mitigation of parameters of radiation pneumonitis. We used a whole animal model, irradiating 9-10-week-old female rats derived from a Wistar strain (WAG/RijCmcr) with a single dose of irradiation to the thorax of 11, 12, 13, 14 or 15 Gy. Our study develops methodology to measure DMFs for morbidity (survival) as well as physiological endpoints such as lung function, taking into account attrition due to lethal radiation-induced pneumonitis. Captopril delivered in drinking water (140-180 mg/m(2)/day, comparable with that given clinically) and started one week after irradiation has a DMF of 1.07-1.17 for morbidity up to 80 days (survival) and 1.21-1.35 for tachypnea at 42 days (at the peak of pneumonitis) after a single dose of ionizing radiation (X-rays). These encouraging results advance our goals, since DMF measurements are essential for drug labeling and comparison with other mitigators.

Changes in global function and regional ventilation and perfusion on SPECT during the course of radiotherapy in patients with non-small-cell lung cancer

PURPOSE

This study aimed to (1) examine changes in dyspnea, global pulmonary function test (PFT) results, and functional activity on ventilation (V)/perfusion (Q) single-photon emission computerized tomography (SPECT) scans during the course of radiation (RT), and (2) factors associated with the changes in patients with non-small-cell lung cancer (NSCLC).

METHODS AND MATERIALS

Fifty-six stage I to III NSCLC patients treated with definitive RT with or without chemotherapy were enrolled prospectively. Dyspnea was graded according to Common Terminology Criteria for Adverse Events version 3.0 prior to and weekly during RT. V/Q SPECT-computed tomography (CT) and PFTs were performed prior to and during RT at approximately 45 Gy. Functions of V and Q activities were assessed using a semiquantitative scoring of SPECT images.

RESULTS

Breathing improved significantly at the third week (mean dyspnea grade, 0.8 vs. 0.6; paired t-test p = 0.011) and worsened during the later course of RT (p > 0.05). Global PFT results did not change significantly, while regional lung function on V/Q SPECT improved significantly after ∼45 Gy. The V defect score (DS) was 4.9 pre-RT versus 4.3 during RT (p = 0.01); Q DS was 4.3 pre-RT versus 4.0 during RT (p < 0.01). Improvements in V and Q functions were seen primarily in the ipsilateral lung (V DS, 1.9 pre-RT versus 1.4 during RT, p < 0.01; Q DS, 1.7 pre-RT versus 1.5 during RT, p < 0.01). Baseline primary tumor volume was significantly correlated with pre-RT V/Q DS (p < 0.01). Patients with central lung tumors had greater interval changes in V and Q than those with more peripheral tumors (p <0.05 for both V and Q DS).

CONCLUSIONS

Regional ventilation and perfusion improved during RT at 45 Gy. This suggests that adaptive planning based on V/Q SPECT during RT may allow sparing of functionally recoverable lung tissue.

Analysis of normal tissue complication probability of the lung using a reliability model

The volume effect of normal tissues and organs is an important factor for predicting normal tissue complication probability (NTCP) following partial, heterogeneous irradiation of organs at risk, and reducing the late sequela by conformal radiation therapy. We have previously developed a reliability model for calculation of NTCP, assuming a parallel architecture of functional subunits (FSU), where a critical number (k) out of the total number of FSUs (N) must be intact for the organ to maintain its function. Published data on radiation-induced lethal pneumonitis and altered breathing rate following partial volume irradiation of the mouse lung were analysed, and critical fraction and corresponding spatial density distribution of FSUs were estimated using this model. The critical fraction (k/N) seemed to be similar for the two endpoints, and a value of 0.7 was found to provide good fit to the experimental data. The critical fraction did not vary throughout the lung, and variation in volume effect cannot therefore be attributed to heterogeneous tissue architecture. On the other hand, our analysis revealed that the observed variation in volume effect of mouse lung may be attributed to heterogeneous spatial distribution in FSU density or also the spatial variation in inactivation probability of the FSUs.

Physiological effects of RF exposure on hypersensitive people by a cell phone

Persons with electromagnetic hypersensitivity (EHS) complain of subjective symptoms such as headaches, insomnia, memory loss etc. resulting from radio frequency (RF) radiation by cellular phones. There have been various EHS provocation studies on heart rate, blood pressure, and subjective symptoms using GSM phones. However, there are few provocation studies on case-control study investigating simultaneously physiological parameters from CDMA phones. In this study, two volunteer groups of 18 self-declared EHS and 19 controls were exposed to both sham and real RF exposures by a CDMA cellular phone for half an hour each. We investigated the physiological parameters such as heart rates, respiration rates, and hear rate variability (HRV). In conclusion, the RF exposure by a CDMA cellular phone did not have any effects on the physiological parameters for both groups.

The Impact of Heart Irradiation on Dose–Volume Effects in the Rat Lung

PURPOSE

To test the hypothesis that heart irradiation increases the risk of a symptomatic radiation-induced loss of lung function (SRILF) and that this can be well-described as a modulation of the functional reserve of the lung.

METHODS AND MATERIALS

Rats were irradiated with 150-MeV protons. Dose-response curves were obtained for a significant increase in breathing frequency after irradiation of 100%, 75%, 50%, or 25% of the total lung volume, either including or excluding the heart from the irradiation field. A significant increase in the mean respiratory rate after 6-12 weeks compared with 0-4 weeks was defined as SRILF, based on biweekly measurements of the respiratory rate. The critical volume (CV) model was used to describe the risk of SRILF. Fits were done using a maximum likelihood method. Consistency between model and data was tested using a previously developed goodness-of-fit test.

RESULTS

The CV model could be fitted consistently to the data for lung irradiation only. However, this fitted model failed to predict the data that also included heart irradiation. Even refitting the model to all data resulted in a significant difference between model and data. These results imply that, although the CV model describes the risk of SRILF when the heart is spared, the model needs to be modified to account for the impact of dose to the heart on the risk of SRILF. Finally, a modified CV model is described that is consistent to all data.

CONCLUSIONS

The detrimental effect of dose to the heart on the incidence of SRILF can be described by a dose dependent decrease in functional reserve of the lung.

Respiratory and cardiovascular responses evoked by tibialis anterior muscle afferent fibers in rats

The muscle metaboreflex is thought to be one of the neural mechanisms involved in the cardiovascular and respiratory adjustments to muscular activity. The afferent arm of the reflex is composed of thinly myelinated group III and unmyelinated group IV sensitive fibers. Such reflex arc had been extensively described in cats, dogs, rabbits and humans. However, results obtained in rats are controversial and the role of the afferent fibers from the tibialis anterior skeletal muscle has never been shown. The purpose of the present experiments was to study the responses of both respiratory and cardiovascular systems following activation of the metabosensitive fibers originating from tibialis anterior muscle in non decerebrated and non vagotomized barbituric anesthetized adult rats. Mean arterial blood pressure, mean arterial blood flow, heart rate and phrenic nerve activity (frequency and amplitude) were monitored during electrically induced fatigue or after intramuscular injection of potassium chloride or lactic acid (specific stimuli of the group III and IV afferent fibers). The experiments were performed under normal condition, then after regional circulatory occlusion, which isolated and maintained the neural drive and abolished humoral communication and after section of the peroneal nerve innervating the tibialis anterior muscle. We showed that cardiorespiratory parameters were increased significantly in response to stimuli under normal conditions and after venous outflow occlusion excluding any participation of central chemoception. No change was observed after nerve section. Our data indicate that changes occurring in rat hindlimb muscle such as the tibialis anterior are sufficient to regulate the cardiorespiratory function via metabosensitive fiber activation.

Changes in Expression of Injury After Irradiation of Increasing Volumes in Rat Lung

PURPOSE

To improve the cure rates of thoracic malignancies by radiation dose escalation, very accurate insight is required in the dose delivery parameters that maximally spare normal lung function. Radiation-induced lung complications are classically divided into an early pneumonitic and a late fibrotic phase. This study investigated the relative dose-volume sensitivity, underlying pathologic findings, and consequentiality of early to late pathologic features.

METHODS AND MATERIALS

We used high-precision, graded dose-volume lung irradiations and followed the time dependency of the morphologic sequelae in relation to overall respiratory function.

RESULTS

Two distinct pathologic lesions were identified in the early postirradiation period (6-12 weeks): vascular inflammation and parenchymal inflammation. Vascular inflammation occurred at single doses as low as 9 Gy. This translated into early respiratory dysfunction only when a large lung volume had been irradiated and was reversible with time. Parenchymal inflammation was seen after higher doses only (onset at 16 Gy), progressed into later fibrotic remodeling but did not translate into dysfunction at a 25% lung volume even after single doses up to 36 Gy.

CONCLUSION

Our data imply that a low dose scattered over a large lung volume causes more early toxicity than an extreme dose confined to a small volume. Such findings are crucial for clinical treatment planning of dose escalations and choices for modern radiotherapy techniques.

Herbivory mitigation through increased water-use efficiency in a leaf-mining moth-apple tree relationship

Herbivory alters plant gas exchange but the effects depend on the type of leaf damage. In contrast to ectophagous insects, leaf miners, by living inside the leaf tissues, do not affect the integrity of the leaf surface. Thus, the effect of leaf miners on CO2 uptake and water-use efficiency by leaves remains unclear. We explored the impacts of the leaf-mining moth Phyllonorycter blancardella (Lepidoptera: Gracillariidae) on light responses of the apple leaf gas exchanges to determine the balance between the negative effects of reduced photosynthesis and potential positive impacts of increased water-use efficiency (WUE). Gas exchange in intact and mined leaf tissues was measured using an infrared gas analyser. The maximal assimilation rate was slightly reduced but the light response of net photosynthesis was not affected in mined leaf tissues. The transpiration rate was far more affected than the assimilation rate in the mine integument as a result of stomatal closure from moderate to high irradiance level. The WUE was about 200% higher in the mined leaf tissues than in intact leaf portions. Our results illustrate a novel mechanism by which plants might minimize losses from herbivore attacks; via trade-offs between the negative impacts on photosynthesis and the positive effects of increased WUE.

Influence of ultraviolet radiation on selected physiological responses of earthworms

The purpose of this study was to investigate the adverse effects of ultraviolet (UV) radiation on earthworms. Earthworms that crawl out of the soil may die within a few hours after sunrise. This study shows that UV exposure can be lethal. In general, UV-B had a stronger damaging effect than UV-A. Different species of earthworms had different tolerances to UV exposure. In this study, Pontoscolex corethrurus showed the highest tolerance of the three tested species to UV radiation, while Amynthas graciliswas the most sensitive. UV radiation induced both acute and chronic responses. The acute response, which occurred immediately on or after UV exposure, was characterized by the appearance of abnormally strong muscle contractions,including S-shaped movements and jumping behavior, possibly caused by bad coordination between the circular and longitudinal muscles. The chronic response included damage to the skin and muscle cells, which resulted in a high mortality rate. Oxygen consumption by A. gracilis was significantly decreased after exposure to UV-A or UV-B. Since the circulation in earthworms is mediated by muscle contraction and the skin is the main organ of respiration, it is reasonable to expect that abnormal muscle contraction and a damaged epithelium could cause suffocation. Because of their sensitive responses, we propose that some earthworms, such as A. gracilis,could serve as a new model for studying UV-induced photodamage.

Involvement of medullary GABAergic and serotonergic raphe neurons in respiratory control: electrophysiological and immunohistochemical studies in rats

In the present study we first examined the possible involvement of the putative neurotransmitters gamma-aminobutyric acid (GABA) and serotonin (5-HT) in raphe-induced facilitatory or inhibitory effects on the respiratory activity of rats. Secondly, we investigated the possibility of spinal projections of GABAergic and serotonergic neurons from the medullary raphe nuclei to the phrenic motor nucleus (PMN). We observed that an intravenous (i.v.) injection of (+)-bicuculline, a GABA(A) receptor antagonist, significantly reduced respiratory inhibition induced by electrical stimulation of the raphe magnus (RM) or the raphe obscurus (RO). On the other hand, an i.v. injection of methysergide, a broad-spectrum 5-HT receptor antagonist, significantly reduced the respiratory facilitation induced by electrical stimulation of the raphe pallidus (RP) or RO. By using a combined method of retrograde tracing with Texas Red injected into the PMN region at segments C4 and C5 and immunohistochemical labeling, we observed that glutamic acid decarboxylase (GAD; a GABA synthesizing enzyme) immunopositive and Texas Red double labeled neurons were predominantly localized in the RM, and additionally in the RO. However 5-HT immunopositive and Texas Red double-labeled neurons were predominantly localized in the RP, and additionally in the RO and RM. These findings suggest that RM-, or RO-induced inhibitory effects, are transmitted, at least in part, to the PMN via a direct GABAergic descending pathway. The RP-, or RO-induced facilitatory effects in rats however, are transmitted via a serotonergic descending pathway.

[Low-intensity laser radiation in therapy of bronchial asthma]

Efficacy of low-intensity laser radiation (LR) was studied by changes in a histamine level in peripheral blood and external respiration function (ERF). A total of 228 patients with exogenic bronchial asthma (EBA) were divided into two groups: 167 patients with nonhormone dependent asthma (group 1) and 61 patients with hormone-dependent bronchial asthma (group 2). Low-intensity LR lowered a histamine level and improved ERF in both group 1 and 2. A definite negative correlation was found between histamine content and ERF parameters. Laser therapy alone is effective in mild EBA. For moderate and severe EBA and hormone-dependent bronchial asthma a combination of conventional drug therapy with low-intensity LR is recommended.

Thermophysiological responses of human volunteers to whole body RF exposure at 220 MHz

Since 1994, our research has demonstrated how thermophysiological responses are mobilized in human volunteers exposed to three radio frequencies, 100, 450, and 2450 MHz. A significant gap in this frequency range is now filled by the present study, conducted at 220 MHz. Thermoregulatory responses of heat loss and heat production were measured in six adult volunteers (five males, one female, aged 24-63 years) during 45 min whole body dorsal exposures to 220 MHz radio frequency (RF) energy. Three power densities (PD = 9, 12, and 15 mW/cm(2) [1 mW/cm(2) = 10 W/m(2)], whole body average normalized specific absorption rate [SAR] = 0.045 [W/kg]/[mW/cm(2)] = 0.0045 [W/kg]/[W/m(2)]) were tested at each of three ambient temperatures (T(a) = 24, 28, and 31 degrees C) plus T(a) controls (no RF). Measured responses included esophageal (T(esoph)) and seven skin temperatures (T(sk)), metabolic rate (M), local sweat rate, and local skin blood flow (SkBF). Derived measures included heart rate (HR), respiration rate, and total evaporative water loss (EWL). Finite difference-time domain (FDTD) modeling of a seated 70 kg human exposed to 220 MHz predicted six localized "hot spots" at which local temperatures were also measured. No changes in M occurred under any test condition, while T(esoph) showed small changes (< or =0.35 degrees C) but never exceeded 37.3 degrees C. As with similar exposures at 100 MHz, local T(sk) changed little and modest increases in SkBF were recorded. At 220 MHz, vigorous sweating occurred at PD = 12 and 15 mW/cm(2), with sweating levels higher than those observed for equivalent PD at 100 MHz. Predicted "hot spots" were confirmed by local temperature measurements. The FDTD model showed the local SAR in deep neural tissues that harbor temperature-sensitive neurons (e.g., brainstem, spinal cord) to be greater at 220 than at 100 MHz. Human exposure at both 220 and 100 MHz results in far less skin heating than occurs during exposure at 450 MHz. However, the exposed subjects thermoregulate efficiently because of increased heat loss responses, particularly sweating. It is clear that these responses are controlled by neural signals from thermosensors deep in the brainstem and spinal cord, rather than those in the skin.

Vagal pulmonary afferents and central respiratory effects of 5-HT in newborn rats

In decerebrate newborn rats, serotonin (5-HT) is a respiratory depressant via activation of 5-HT2 receptors, whereas it evokes respiratory stimulant effects when applied to the isolated brainstem obtained from the newborn rat. This discrepancy could be due to deafferentation in the in vitro preparation. The aim of our study was to analyse the role of vagal afferents in the modulation of central respiratory effects of 5-HT. In decerebrate cervically or abdominally bivagotomized newborn rats aged between 0 and 3 days, we recorded electrical activity from the diaphragm and from a hypoglossally innervated tongue muscle, as well as cardiac frequency (Fc), before and after application of 5-HT to the floor of the IVth ventricle. The effects of related agents (a 5-HT1A agonist, 8-OH DPAT, and a 5-HT2 agonist, DOI) were studied in cervically bivagotomized animals. For comparison, and to assess the spontaneous variability in inspiratory frequency (Fi) and Fc, sham groups were studied. Each group comprised ten newborn rats. In cervically bivagotomized newborn rats, 5-HT induces a significant increase in Fi, which is the opposite to that observed in decerebrate newborn rats with intact vagi. This respiratory effect is mediated in particular, via activation of 5-HT1A. By contrast, in abdominally bivagotomized newborn rats, a decrease in Fi was observed in response to 5-HT (as previously described in decerebrate animals with intact vagi). We conclude that pulmonary vagal afferents modulate the central respiratory action of 5-HT in decerebrate newborn rats, explaining the conflicting results between in vivo and in vitro experiments.

Pulmonary radiation injury: identification of risk factors associated with regional hypersensitivity

Effective radiation treatment of thoracic tumors is often limited by radiosensitivity of surrounding tissues. Several experimental studies have suggested variations in radiosensitivity of different pulmonary regions. Mice and rat studies in part contradict each other and urge for a more detailed analysis. This study was designed to obtain a more comprehensive insight in radiation injury development, expression, and its regional heterogeneity in lung. The latter is obviously highly critical for optimization of radiotherapy treatment plans and may shed light on the mechanisms of lung dysfunction after irradiation. Six different but volume-equal regions in rat lung were irradiated. Whereas the severity of damage, as seen in histologic analysis, was comparable in all regions, the degree of lung dysfunction, measured as breathing rates, largely varied. During the pneumonitic phase (early: 6-12 weeks), the most sensitive regions contained a substantial part of alveolar lung parenchyma. Also, a trend for hypersensitivity was observed when the heart lay in the irradiation field. In the fibrotic phase (late: 34-38 weeks), lung parenchyma and heart-encompassing regions were the most sensitive. No impact of the heart was observed during the intermediate phase (16-28 weeks). The severity of respiratory dysfunction after partial thoracic irradiation is likely governed by an interaction between pulmonary and cardiac functional deficits. As a repercussion, more severe acute and delayed toxicity should be expected after combined lung and heart irradiation. This should be considered in the process of radiotherapy treatment planning of thoracic malignancies.

INTEGRATION OF THE HEART RHYTHMOGENESIS LEVELS: HEART RHYTHM GENERATOR IN THE BRAIN

We propose that along with the intracardiac pacemaker, a generator of cardiac rhythm exists in the central nervous system--in the efferent structures of the cardiovascular center of the medullar oblongata. Signals in the medulla oblongata arise as a result of the hierarchic interaction of the brain structures. Neural signals originating there in the form of bursts of impulses conduct to the heart along the vagus nerves and after interaction with cardiac pacemaker structures, cause generation of the cardiac pulse in exact accordance with the frequency of "neural bursts". The intrinsic cardiac rhythm generator (the sinus node) is a life-sustaining factor that maintains the heart pumping function when the central nervous system is in a stage of deep inhibition, (e.g., under anesthesia or during unconsciousness). The brain generator is the factor that provides heart adaptive reactions in behaving organism. The integration of the two levels of rhythmogenesis in the brain and heart provides reliability and functional perfection of the cardiac rhythm generation system in the whole organism.

Chronic hypoxia abolishes expiratory prolongation following carotid sinus nerve stimulation in the anesthetized rat

In anesthetized rats, increases in phrenic nerve (PN) amplitude and frequency during brief periods of hypoxia or electrical stimulation of the carotid sinus nerve (CSN) are followed by an increase in expiratory duration. We investigated the effects of chronic exposure to hypoxia on PN responses to CSN stimulation. In Inactin anesthetized (100 mg/kg) Sprague-Dawley rats PN discharge and arterial pressure responses to 10-120 s of CSN stimulation (20 Hz, 0.2 ms duration pulses) were recorded after 7-10 days exposure to hypoxia (10 +/- .5% O2). In normoxic rats, the degree of CSN-evoked expiratory prolongation was dependent upon the duration of CSN stimulation. CSN-evoked increases in PN burst amplitude were not different comparing chronic hypoxic rats to rats maintained at normoxia while CSN-evoked increases in PN burst frequency were greater in chronic hypoxic rats (p<.05). CSN-evoked expiratory prolongation was abolished in chronic hypoxic rats. Following chronic hypoxia, changes occur within the central processing of arterial chemoreceptor inputs so that CSN stimulation evokes an enhanced PN frequency response and no expiratory prolongation.

The protective effect of recombinant human keratinocyte growth factor on radiation-induced pulmonary toxicity in rats

PURPOSE

Radiation-induced lung toxicity is a significant dose-limiting side effect of radiotherapy for thoracic tumors. Recombinant human keratinocyte growth factor (rHuKGF) has been shown to be a mitogen for type II pneumocytes. The purpose of this study was to determine whether rHuKGF prevents or ameliorates the severity of late lung damage from fractionated irradiation in a rat model.

METHODS AND MATERIALS

Female Fisher 344 rats were irradiated to the right hemithorax with a dose of 40 Gy/5 fractions/5 days. rHuKGF at dose of 5 mg/kg or 15 mg/kg was given via a single intravenous injection 10 min after the last fraction of irradiation. Animals were followed for 6 months after irradiation.

RESULTS

The breathing rate increased beginning at 6 weeks and reached a peak at 14 weeks after irradiation. The average breathing frequencies in the irradiated groups with rHuKGF (5 mg/kg and 15 mg/kg) treatment were significantly lower than that in the group receiving radiation without rHuKGF (116.5 +/- 1.0 and 115.2 +/- 0.8 vs 123.5 +/- 1.2 breaths/min, p < 0.01). The severity of lung fibrosis and the level of immunoreactivity of integrin alphavbeta6, TGFbeta1, type II TGFbeta receptor, Smad3, and phosphorylated Smad2/3 were significantly decreased only in the group receiving irradiation plus high-dose rHuKGF treatment compared with irradiation plus vehicle group, suggesting a dose response for the effect of rHuKGF.

CONCLUSIONS

This study is the first to demonstrate that rHuKGF treatment immediately after irradiation protects against late radiation-induced pulmonary toxicity. These results suggest that restoration of the integrity of the pulmonary epithelium via rHuKGF stimulation may downregulate the TGF-beta-mediated fibrosis pathway. These data also support the use of rHuKGF in a clinical trial designed to prevent radiation-induced lung injury.

Effects of boron neutron capture irradiation on the normal lung of rats

The whole lung of rats was irradiated with X-rays, thermal neutrons, or thermal neutrons in the presence of p-boronophenylalanine (BPA). A >/= 20% increase in breathing rate, in the period 40-80 days after irradiation, was indicative of radiation-induced pneumonitis. The ED(50) (+/-SE) for a >/= 20% increase in breathing rate, relative to age-matched controls, was 11.6 +/- 0.13 Gy for X-rays and 9.6 +/- 0.08 Gy for neutrons only. This indicated a thermal neutron beam RBE of 1.2 and an RBE of 2.2 for the high-LET components of the dose, assuming a dose reduction factor of 1.0 for gamma rays. Preliminary data indicate the compound biological effectiveness factor for BPA in the lung is approximately 1.5.

Dosimetric effect of respiratory motion in external beam radiotherapy of the lung

BACKGROUND AND PURPOSE

To study the effect of breathing motion on gross tumor volume (GTV) coverage for lung tumors using dose-volume histograms and relevant dosimetric indices.

PATIENTS AND METHODS

Treatment plans were chosen for 12 patients treated at our institution for lung carcinoma. GTV volumes of these patients ranged from 1.2 to 97.3 cm(3). A margin of 1-2 cm was used to generate the planning target volume (PTV). Additional margins of 0.6-1.0 cm were added to the PTV when designing treatment portals. For the purposes of TCP calculation, the prescription dose was assumed to be 70 Gy to remove the effects of prescription differences. Setup error was incorporated into the evaluation of treatment plans with a systematic component of sigma(RL) = 0.2 cm, sigma(AP) = 0.2 cm, and sigma(SI) = 0.3 cm and a random component of sigma(RL) = 0.3 cm, sigma(AP) = 0.3 cm, and sigma(SI) = 0.3 cm. Breathing motion was incorporated into these plans based on an independent analysis of fluoroscopic movies of the diaphragm for 7 patients. The systematic component of breathing motion (sigma(RL) = 0.3 cm, sigma(AP) = 0.2 cm, and sigma(SI) = 0.6 cm) was incorporated into the treatment plans on a slice by slice basis. The intrafractional component of breathing motion (sigma(RL) = 0.3 cm, sigma(AP) = 0.2 cm, and sigma(SI) = 0.6 cm) was incorporated by averaging the dose calculation over all displacements of the breathing cycle. Each patient was simulated 500 times to discern the range of possible outcomes. The simulations were repeated for a worst case scenario which used only breathing data with a large diaphragmatic excursion, both with and without intrafractional breathing motion.

RESULTS

Dose to 95% of the GTV (D95), volume of the GTV receiving 95% of the prescription dose (V95) and TCP changed an average of -1.4+/-4.2, -1.0+/-3.3, and -1.4+/-3.8%, respectively, with the incorporation of normal breathing effects. In the worst case scenario (heavy breathers), D95 and V95 changed an average of -9.8+/-10.1 and -8.3+/-11.3%, respectively, and TCP changed by -8.1+/-9.1%. GTVs with volumes greater than 60 cm(3) showed stronger sensitivity to breathing especially if the shape was non-ellipsoidal. In the normal breathing case, the probability of a decrease in D95, V95, or TCP of a magnitude greater than 10% is less than 4%, and in the worse case scenario this probability is approximately 30-40% with intrafractional breathing motion included, and less than 10% with intrafractional breathing motion not included.

CONCLUSIONS

With the PTV margins routinely used at our center, the effects of normal breathing on coverage are small on the average, with a less than 4% chance of a 10% or greater decrease in D95, V95, or TCP. However, in patients with large respiration-induced motion, the effect can be significant and efforts to identify such patients are important.

Possible involvement of the facial nucleus in regulation of respiration in rats

The facial nucleus (FN) has been known as a motor nucleus to control the activity of the facial skeletal muscles by its efferent somatic motoneurons. Much less, however, is known about the non-motor control functions of its interneurons. The present study was designed to investigate if the interneurons of the FN participate in controlling rhythmic respiration in the sodium thiopental-anesthetized and vagotomized Sprague-Dawley rats with facial motoneurons retrogradely degenerated with techniques of electrical and chemical stimulation of the FN and extracellular recording of discharge of neurons in the FN. Single pulse stimulation (75-100 microA, 0.2 ms) of the FN during inspiration caused a transient restrain in phrenic discharge. Short train stimulation (75-100 microA, 0.2 ms, 100 Hz, 3-5 pulses) delivered during the early- or mid-term of inspiration augmented the inspiratory duration, but switched the inspiration off when delivered during the later stage of inspiration. Short train stimulation delivered during expiration prolonged the expiratory duration. Continuous stimulation could inhibit the inspiration. Microinjection of kainic acid into the FN caused an augmentation in inspiratory duration and amplitude and in expiratory duration. These data indicate that the interneurons of the FN might participate in the modulation of respiration. Different discharge patterns of interneurons in the FN, interestingly some respiratory related patterns, were observed, which provide a possible structural basis for the role of the FN in respiratory regulation.

Effect of administration of lovastatin on the development of late pulmonary effects after whole-lung irradiation in a murine model

Our group's work on late radiation effects has been governed by the hypothesis that the effects observed in normal tissues are a consequence of multicellular interactions through a network of mediators. Further, we believe that inflammation is a necessary component of this process. We therefore investigated whether the recruitment of mononuclear cells, observed during the pneumonitic period in the irradiated normal lung, is dependent on the expression of chemokines, notably Mcp1. Since statins have been shown to reduce chemokine expression and inflammatory cell recruitment, we specifically examined whether statins could be used to reduce monocyte recruitment. Mice received 15 Gy whole-lung irradiation; treated groups were administered lovastatin three times weekly starting either immediately or 8 weeks postirradiation. At subsequent intervals, animals were killed humanely, and cellular, mRNA and protein analyses were undertaken. Statin-treated animals demonstrated a statistically significant reduction in both macrophage and lymphocyte populations in the lung compared to radiation alone as well as improved rates of survival and decreased collagen content. In addition, ELISA measurements showed that radiation-induced increases in Mcp1 protein were reduced by statin treatment. Additional experiments are needed to assess whether statins offer a potential treatment for the amelioration of late effects in breast and lung cancer patients undergoing radiation therapy.

Changes in the Thermal Dissipation and the Electron Flow in the Water–Water Cycle in Rice Grown Under Conditions of Physiologically Low Temperature

Effects of low temperature on chlorophyll (Chl) fluorescence, gas exchange rate, the amounts of xanthophyll cycle pigments (Xp) and the activities of several antioxidant enzymes were examined in the 8th leaf of two rice (Oryza sativa L.) cultivars (japonica and indica types) and rbcS antisense rice. All plants were grown hydroponically at 25/20 degrees C (day/night), and then exposed to 20/17 degrees C (day/night) after full expansion of the 8th leaf, or exposed to either 20/17 degrees C or 15/13 degrees C (day/night) during the expansion of the 8th leaf. All plants exposed to low temperatures showed a decrease in CO(2) assimilation rate without photoinhibition, and increases in the fraction of thermal dissipation in PSII, and in the electron flux through the water-water cycle (WWC) were observed. Although the increase of thermal dissipation was associated with increases in the ratio of carotenoids to Chl, the ratio of Xp to carotenoids and the de-epoxidation state of Xp, the increase of the electron flux of WWC was not accompanied by an increase in the activities of antioxidant enzymes. Such photoprotective responses did not differ between during and after full expansion of the leaf, and did not differ among the three genotypes. Quantitative analyses on the dissipation of excess light energy showed that thermal dissipation makes a larger contribution than WWC. Thus, although low temperature led to a decrease in CO(2) assimilation, rice potentially coped with the excess light energy by increasing the thermal dissipation and the electron flux of WWC under low temperature irrespective of leaf development and genotypes.

Loco-regional differences in pulmonary function and density after partial rat lung irradiation

PURPOSE

The purpose of this study was to explore regional differences in radiosensitivity of rat lung using lung function and computed tomography (CT) density as endpoints.

METHODS

At first, CT scans were used to determine rat lung volumes. The data obtained enabled the design of accurate collimators to irradiate 50% of the total lung volume for the apex, base, left, right, mediastinal and lateral part of the lung. Male Wistar rats were irradiated with a single dose of 18 Gy of orthovoltage X-rays. Further rat thorax CT scans were made before and 4, 16, 26, and 52 weeks after irradiation to measure in vivo lung density changes indicative of lung damage. To evaluate overall lung function, breathing frequencies were measured biweekly starting 1 week before irradiation.

RESULTS

Qualitative analysis of the CT scans showed clear density changes for all irradiated lung volumes, with the most prominent changes present in the mediastinal and left group at 26 weeks after radiation. Quantitative analysis using average density changes of whole lungs did not adequately describe the differences in radiation response between the treated groups. However, analysis of the density changes of the irradiated and non-irradiated regions of interest (ROI) more closely matched with the qualitative observations. Breathing frequencies (BF) were only increased after 50% left lung irradiation, indicating that the hypersensitivity of the mediastinal part as assessed by CT analysis, does not result in functional changes.

CONCLUSIONS

For both BF and CT (best described by ROI analysis), differences in regional lung radiosensitivity were observed. The presentation of lung damage either as function loss or density changes do not necessarily coincide, meaning that for each endpoint the regional sensitivity may be different.

Respiratory modulation of heart rate and blood pressure during Cheyne-Stokes respiration

Cheyne-Stokes respiration (CSR) is a form of periodic breathing associated with oscillations in heart rate (HR) and blood pressure (BP), which have previously been attributed to the effects of intermittent hypoxia and arousals from sleep. We herein review the major findings from a series of experiments, in which we explored the possibility that the ventilatory oscillations of CSR can independently modulate HR and BP. Using frequency spectral analysis, we showed that CSR in patients with heart failure causes oscillations in HR and BP that are eliminated by abolition of ventilatory oscillations, but persist during administration of supplemental O2 sufficient to prevent hypoxia. Analysis of the effects of arousals showed they have little or no effect on HR or BP independent of associated changes in ventilation. Finally, we showed that during simulated CSR, healthy awake patients were able to cause HR and BP oscillations in the absence of hypoxia or arousals. We conclude that ventilatory oscillations during Cheyne-Stokes respiration can modulate HR and BP independent of the effects of hypoxia and arousals from sleep.

Assessment of the protective effect of amifostine on radiation-induced pulmonary toxicity

The objective of this study was to assess the radioprotective effects of amifostine in the rat model of radiation-induced lung injury using fractionated doses of radiation, to determine whether amifostine given before irradiation protects tumor from radiation cytotoxicity, and to determine whether changes in plasma levels of transforming growth factor (TGF)-beta correlate with radioprotective effect of amifostine. R3230 AC mammary adenocarcinoma was transplanted on the right posterior chest wall of female Fisher-344 rats. Both tumor-bearing and non-tumor-bearing animals were irradiated to the tumor or right lung using 4 MV photons and fractionated dose of 35 Gy/5 fractions/5 days. Animals with tumors and those without were randomized into 4 groups, respectively (8 to 10 rats per group), to receive (1) radiation alone; (2) radiation + amifostine; (3) amifostine alone; (4) sham radiation. Amifostine (150 mg/kg) was given intraperitoneally 30 minutes before each fraction of irradiation. The tumor size was measured twice a week. Breathing rate was assessed every 2 weeks. TGF-beta levels in plasma were assessed monthly after treatment. Six months after irradiation, animals were euthanized and lung tissue was processed for hydroxyproline content analysis. A significant increase in breathing frequency started 9 weeks after irradiation in animals that received radiation only. In the radiation + amifostine group, there was both a delay and a significantly lower peak in breathing frequency (P < .001). Hydroxyproline content was higher in the radiation-alone group than in rats given amifostine prior to radiation (P < .05). The TGF-beta levels in plasma showed an increase from 1 to 3 months after radiation, peaking at 2 months in the rats with (2.80 +/- 0.23) or without (5.32 +/- 1.21) amifostine compared to sham irradiation. TGF-beta levels were significantly lower at 1 to 3 months in rats receiving amifostine plus radiation versus those receiving radiation alone. Tumor growth delay and regrowth rate after radiation were not different between radiation-alone and radiation + amifostine groups. This study confirms the protective effect of amifostine in reducing radiation-induced pulmonary toxicity. No tumor protection was demonstrated after fractionated radiotherapy. The reduction in pulmonary injury with amifostine in paralleling lower plasma levels of TGF-beta, suggesting that monitoring plasma levels of this cytokine may reflect the efficacy of an intervention aimed at preventing radiation-induced lung injury.

A small molecular weight catalytic metalloporphyrin antioxidant with superoxide dismutase (SOD) mimetic properties protects lungs from radiation-induced injury

Radiation therapy (RT) is an important therapeutic modality in the treatment of thoracic tumors. The maximum doses to these tumors are often limited by the radiation tolerance of lung tissues. Lung injury from ionizing radiation is believed to be a consequence of oxidative stress and a cascade of cytokine activity. Superoxide dismutase (SOD) is a key enzyme in cellular defenses against oxidative damage. The objective of this study was to determine whether the SOD mimetic AEOL 10113 [manganese (III) mesotetrakis (N-ethylpyridinium-2-yl) porphyrin (MnTE-2-PyP(5+))] increases the tolerance of lung to ionizing radiation. AEOL 10113 was able to significantly reduce the severity of RT-induced lung injury. This was strongly supported with histopathology results and measurements of collagen deposition (hydroxyproline content). There was a significant reduction in the plasma level of the profibrogenic cytokine transforming growth factor-beta (TGF-beta) in the group of rats receiving RT + AEOL 10113. In conclusion, the novel SOD mimetic, AEOL 10113, demonstrates a significant protective effect from radiation-induced lung injury.

Radioprotection of lungs by amifostine is associated with reduction in profibrogenic cytokine activity

Radiation-induced pulmonary toxicity causes significant morbidity and mortality in patients irradiated for lung cancer, breast cancer, lymphoma or thymoma. Amifostine is an important drug in the emerging field of cytoprotection. Recent advances in our understanding of the mechanism of radiation-induced injury at the molecular and cellular levels have stimulated interest in the development of effective radioprotective strategies. Accumulation of macrophages with associated production of reactive oxygen species (ROS) and production and activation of cytokines is a key process involved in the pathophysiology of radiation injury in the lung. The purpose of this study was to determine whether the mechanism of radioprotection by amifostine includes reduction in both macrophage activity and the expression and activation of profibrogenic cytokines. Our results demonstrated a reduction in both functional and histological radiation-induced lung injury by amifostine. In addition, this study is the first to demonstrate that amifostine given prior to irradiation reduced both the accumulation of macrophages and the expression/activation of lung tissue Tgfb1 which was followed by the reduction of plasma Tgfb1 levels during the development of radiation-induced lung injury. Future studies are needed to determine whether administration of amifostine both during and after radiotherapy may further increase its radioprotective effect.

Effects of solar radiation and feeding time on behavior, immune response and production of lactating ewes under high ambient temperature

A 6-wk trial was performed with 40 late-lactation Comisana ewes, which were either exposed to or protected from solar radiation and fed either in the morning (EXPM, PROM) or afternoon (EXPA, PROA) during summer in a Mediterranean climate. Behavioral traits of ewes were recorded once per week from 0800 to 2000 h. Rectal temperature (RT) and respiration rate (RR) were measured twice weekly at 1430 h. The phytohemagglutinin (PHA) skin test was performed to induce nonspecific delayed-type hypersensitivity at d 10, 20, and 32 of the experiment. Jugular blood samples were taken from ewes at the beginning and at d 21 and 42 of the experiment. Ewe milk yield was recorded daily. Individual milk samples were analyzed weekly for milk composition, coagulating properties, somatic cell count (SCC) and polymorphonuclear neutrophil leukocyte counts (PMNLC) and every 2 wk for bacteriological characteristics. Solar radiation and the interaction of solar radiation x time of feeding had significant effects on rectal temperatures. EXPM ewes had higher rectal temperatures than EXPA ewes, which in turn exhibited higher RT compared with PROM and PROA ewes. EXP groups also had significantly higher respiration rates than PRO groups. Immune response was lower in EXPM ewes at d 10 and in EXPM, EXPA, and PROM animals at d 20 compared with PROA ewes. Exposure to solar radiation resulted in decreased plasma concentrations of alanine amino-transferase, alkaline phosphatase, potassium, and magnesium, as well as in increased levels of nonesterified fatty acids and aspartate amino-transferase. Milk yield and composition were not changed by exposure to solar radiation and time of feeding, but the EXPM treatment resulted in lower yields of casein and fat and reduced clot firmness compared with the three other treatments. Milk SCC was similar across treatments, but PMNLC was higher in EXPM than in PROM and PROA milk. EXPM animals also had the greatest amounts of total and fecal coliforms and of Pseudomonadaceae as well as the highest number of mastitis related pathogens in their milk. Results suggest that provision of shaded areas can play a major role in helping lactating ewes to minimize the adverse effects of high ambient temperatures on thermal balance and energy and mineral metabolism. Changing the time of feeding to late afternoon may be beneficial to exposed ewes in lowering their heat loads during the warmest hours of the day, thereby reducing the detrimental impact of thermal stress on immune function and udder health.

Comparison of three rat strains for development of radiation-induced lung injury after hemithoracic irradiation

The purpose of this study is to define differences in radiation sensitivity among rat strains using breathing frequency and lung perfusion as end points of radiation-induced lung injury. The results have confirmed previous findings in mice showing that under stringently controlled iso-dose/volume irradiation conditions, substantial differences can be found in susceptibility to functional lung damage after radiation.

Effect of gamma-irradiation on phenylalanine ammonia-lyase activity, total phenolic content, and respiration of mushrooms (Agaricus bisporus)

Ionizing treatments were applied at 0.5 kGy, 1.5 kGy, and 2.5 kGy to edible mature mushrooms (Agaricus bisporus, albidus) in order to assess the effect of the gamma-irradiation on some biochemical parameters. Irradiation at doses of 1.5 kGy and 2.5 kGy reduced significantly (p < or = 0.05) the rate of respiration of the mushrooms, compared to that of samples irradiated at 0.5 kGy and nonirradiated control samples (C). Ionizing treatments increased significantly (p < or = 0.05) the phenylalanine ammonia-lyase (PAL) activity and total phenols concentration between days 1 and 4. From days 3-4, to the end of the storage period (day 12), both PAL activity and total phenols in the irradiated samples (I) collapsed to lower values. In contrast, the activity of polyphenol oxidase (PPO) increased until days 7, 9, and 12 for samples treated at 0.5, 1, and 2 kGy, respectively. Color measurements showed a loss of whiteness (L value) during storage. After day 4, however, the effectiveness of gamma-irradiation became apparent, and highest L values were obtained for I only.

Body heating induced by sub-resonant (350 MHz) microwave irradiation: cardiovascular and respiratory responses in anesthetized rats

These experiments were designed to investigate the effects of sub-resonant microwave (MW) exposure (350 MHz, E orientation, average power density 38 mW/cm2, average whole-body specific absorption rate 13.2 W/kg) on selected physiological parameters. The increase in peripheral body temperature during 350 MHz exposure was greater than that in earlier experiments performed at 700 MHz (resonance). Heart rate and mean arterial blood pressure were significantly elevated during a 1 degree C increase in colonic temperature due to 350 MHz exposure; respiratory rate showed no significant change. The results are consistent with other investigators' reports comparing sub-resonance exposures with those at resonance and above.

Cardiovascular and thermal effects of microwave irradiation at 1 and/or 10 GHz in anesthetized rats

Relatively large thermal gradients may exist during exposure of an animal to microwaves (MWs), particularly at high frequencies. Differences in thermal gradients within the body may lead to noticeable differences in the magnitude of cardiovascular changes resulting from MW exposure. This study compares the thermal distribution and cardiovascular effects of exposure to a single MW frequency with effects of simultaneous exposure to two frequencies. Ketamine-anesthetized male Sprague-Dawley rats (n = 58) were exposed individually to one of three conditions: 1-GHz, 10-GHz, or combined 1- and 10-GHz MWs at an equivalent whole-body specific absorption rate of 12 W/kg. The continuous-wave irradiation was conducted under far-field conditions with animals in E orientation (left lateral exposure, long axis parallel to the electric field) or in H orientation (left lateral exposure, long axis perpendicular to the electric field). Irradiation was started when colonic temperature was 37.5 degrees C and was continued until lethal temperatures were attained. Colonic, tympanic, left and right subcutaneous, and tail temperatures, and arterial blood pressure, heart rate, and respiratory rate were continuously recorded. In both E and H orientations, survival time (i.e., time from colonic temperature of 37.5 degrees C until death) was lowest in animals exposed at 1-GHz, intermediate in those exposed at 1- and 10-GHz combined, and greatest in the 10-GHz group (most differences statistically significant). At all sites (with the exception of right subcutaneous), temperature values in the 1- and 10-GHz combined group were between those of the single-frequency exposure groups in both E and H orientations. During irradiation, arterial blood pressure initially increased and then decreased until death. Heart rate increased throughout the exposure period. The general, overall patterns of these changes were similar in all groups. The results indicate that no unusual physiological responses occur during multi-frequency MW exposure, when compared with results of single-frequency exposure. Bioelectromagnetics 21:159-166, 2000. Published 2000 Wiley-Liss, Inc.

Predictive respiratory complication quotient predicts pulmonary complications in thoracic surgical patients

BACKGROUND

This study was designed to develop an accurate preoperative index of prediction of outcome and hospital charges after lung resection with standard available pulmonary tests in a tertiary cancer center.

METHODS

Sixty-one consecutive patients undergoing pulmonary resections were evaluated. All patients underwent spirometry, carbon monoxide diffusion capacity, split lung function testing, and room air blood gas analysis at rest and after a 2-minute step climb. The thoracic prospective data base and patient charts were reviewed for length of hospitalization, postoperative length of stay, and complications requiring therapy. Logistic regression analysis of the preoperative data, operation and postoperative outcome was used to develop a new postoperative predictive index: the predictive respiratory complication quotient (PRQ). We describe the design of the equation for the probability of serious pulmonary complications, hospital stay, and hospital charges based on PRQ.

RESULTS

Ten of 12 patients with a PRQ less than 2,200 suffered serious pulmonary complications of pneumonia, respiratory insufficiency, hypoxemia, and death. Forty-nine patients with a PRQ more than 2,200 did not experience any pulmonary complications. Postoperative length of stay and hospital charges correlated with the PRQ.

CONCLUSIONS

A construct such as the PRQ may provide a better prediction of outcome than its individual parts. We identified an important underlying relationship between intensive care unit stay, hospital stay and charges, and our index. A PRQ of less than 2,200 was associated with an increased risk of pulmonary complications and mortality.

A descriptive study of pulmonary complications after postoperative radiation therapy in node-positive stage II breast cancer

This study was conducted to assess the frequencies of symptomatic pulmonary complications following adjuvant postoperative radiotherapy using different treatment techniques in patients with Stage II node-positive breast cancer. During 1991-1993, 177 patients were referred to the Radiotherapy Department of Stockholm Söder Hospital; 144 after modified radical mastectomy and 33 after partial mastectomy. The records of these patients were studied retrospectively for clinically diagnosed radiotherapy-induced lung complications 1-7 months after treatment. Thirty-three of 138 patients (24%) irradiated after modified radical mastectomy developed pulmonary complications and 20 (14%) of these were diagnosed as severe, i.e. needing medical treatment with corticosteroids. No statistically significant difference could be found between the different electron energies used for treating the chest wall and the frequency of respiratory side-effects. Eighteen of 33 patients completed the prescribed treatment after partial mastectomy. Nine of these 18 patients (50%) developed pulmonary complications and 4 (22%) developed severe reactions. Fifteen patients received alternative treatments. With the techniques used after partial mastectomy the median central lung distance was 32 mm among the patients who experienced respiratory side-effects compared with 25 mm among the patients who were not affected (p = 0.03). This study identifies acute/subacute pulmonary side-effects as a clinically significant problem. Prospective follow-up with lung function tests, identification of risk factors, and individual lung dose volume histograms is warranted to assess the long-term implications.

Spatial heterogeneity of the volume effect for radiation pneumonitis in mouse lung

PURPOSE

In a previous study to determine the effect of partial volume irradiation on damage and morbidity from pneumonitis in mouse lung, a critical determinant of the volume effect was the spatial location of the irradiated subvolume within the lung. The goals of the present study were to (a) define the dose-volume effect curves for radiation pneumonitis in mouse lung, (b) define the threshold volume, and (c) further investigate the spatial heterogeneity of the radiosensitivity of mouse lung.

METHODS AND MATERIALS

Eight fractional volumes ranging from 94% to 17% of the lungs of C3Hf/Kam mice were irradiated with single doses ranging from 12 to 22 Gy, depending on the volume irradiated. The fractional volumes irradiated were determined from computed tomographic scans of mouse lung. To determine the effect of location of irradiated subvolume, equivalent volumes in the base and the apex were irradiated by shielding the prescribed adjacent volume in the apex or base respectively. Dose-response curves of breathing rate at 22 weeks and lethality at 28 weeks were constructed for each subvolume irradiated in the apex or base and fitted by logit analysis, and ED50s and LD50s with 95% confidence limits obtained, respectively. Lungs from dead mice or mice sacrificed when moribund were examined for histologic signs of pneumonitis.

RESULTS

Irradiation of any of the eight subvolumes in the base yielded a consistently lower isoeffect dose for both assays of radiation pneumonitis than if the same irradiated subvolume was located in the apex. Plots of isoeffect dose for breathing rate as a function of subvolume irradiated in the base or apex showed that these curves were not linear but exhibited a plateau between irradiated volumes of 70% and 80% in both the apex and base. A similar curve was obtained for lethality and volume irradiated in the base. A threshold volume, i.e., irradiation of that volume that should produce no changes in breathing rate or mortality, was dependent on the location of the irradiated subvolume.

CONCLUSION

The response of mouse lung to partial volume irradiation is heterogeneous and is critically dependent on the specific location of the irradiated subvolume in the lung, i.e., a given subvolume in the base is consistently more sensitive than the same subvolume in the apex using either breathing rate or lethality as assays of radiation pneumonitis. We suggest that this heterogeneity is due to the anatomy of the tracheobronchial tree, i.e., to the distribution of non-gas exchange-conducting airways in the irradiated volume. These data have implications for the modeling of dose-volume effects in the lung and the prediction of normal tissue complication probabilities for radiation pneumonitis in humans.

Age does not affect thermal and cardiorespiratory responses to microwave heating in calorically restricted rats

This study sought to determine whether age influences the thermal distribution and cardiorespiratory responses to 35 GHz microwave (MW) heating. Male Sprague-Dawley rats (n = 8/group) 3 to 4 mo old (young), 15 to 16 mo old (middle-aged), and 24 to 25 mo old (old) were used. All animals were restricted to 63% of ad libitum feed. Rats were anesthetized (ketamine) and a catheter was placed into a carotid artery for measurement of mean arterial blood pressure (MAP). Anesthetized rats were then exposed to MWs until death, while measuring MAP, heart rate and temperatures at five sites (colonic, left and right tympanic, subcutaneous, and tail). Before MW exposure, there were no significant (p < .05) differences among age groups in measured parameters. MW produced increases in temperature at each of the measured sites; temperatures at death did not differ between groups. Heart rate increased throughout MW exposure, in a statistically identical manner in all age groups. MAP was initially well maintained and then, in the latter phases of heating, precipitously declined until death, with no discernible age-related difference. Respiration rate was not altered by MW exposure in any group. Finally, there were no group differences in the MW exposure time required to induce death. Thus, age does not alter thermal and cardiorespiratory responses to 35 GHz MW heating in food-restricted rats.

[Intravenous laser irradiation of the blood at the health-resort stage of treatment for bronchial asthma patients]

The efficiency of spa treatment in combination with intravenous He-Ne laser (wavelength 0.63 microns) radiation of the blood was studied in 152 patients with bronchial asthma of endogenous genesis, mainly with that of moderate severity. By the end of 24-day treatment there were clinical improvements, better external respiratory parameters, and alleviated inflammation.

Recovery of overall and local lung function loss 18 months after irradiation for malignant lymphoma

PURPOSE

To determine the local and overall pulmonary injury 3 to 18 months after irradiation and to investigate whether the changes in overall lung function can be predicted using the three-dimensional (3-D) dose distribution in combination with dose-effect relations for local injury; and to study the influence of chemotherapy on the injury.

PATIENTS AND METHODS

Local perfusion (Q), ventilation (V), and tissue density were measured in 25 patients treated for malignant lymphoma, before, 3 to 4 months after, and 18 months after irradiation. Dose-effect relations for local injury, calculated using correlated single-photon emission computed tomographic (SPECT) and computed tomographic (CT) data, were combined with the 3-D dose distribution, to calculate the estimated mean local changes over the complete lung for each patient. The result was correlated with the actual changes in pulmonary function.

RESULTS

A dose-dependent increase with injury was observed at 3 to 4 months after irradiation, which at 18 months had recovered by approximately 50% to 60%. The estimated mean relative reduction of local Q predicted the change in overall lung function within 10% of the actually observed values in 63% to 73% of patients. Chemotherapy given before radiotherapy enhanced radiation-induced reduction of local Q significantly, with dose-modifying factors of 1.22 and 1.37 at 3 to 4 months and 18 months, respectively.

CONCLUSION

Partial recovery of radiation-induced reduction of local and overall lung function was observed at 18 months after irradiation. The overall functional outcome of most patients could be well predicted, based on the estimated mean local injury over the complete lung. Chemotherapy given before radiotherapy enhanced the radiation-induced reduction of local Q.

Radiosensitisation in normal tissues with oxygen, carbogen or nicotinamide: therapeutic gain comparisons for fractionated x-ray schedules

METHODS

Radiosensitisation with oxygen, carbogen or nicotinamide alone and oxygen or carbogen combined with nicotinamide was compared in early and late responding normal tissues in rodents. X-ray treatments were delivered as single doses or fractionated schedules of 2 fractions in 1 day, 2, 12 and 36 fractions in an overall time of 12 days and 10 fractions in 5 or 12 days. Acute skin reactions, survival of intestinal crypts, breathing rate, reduction in the packed red-cell volume and clearance of 51Cr-EDTA were used as assays of epidermal, gut, lung and renal damage.

RESULTS

Relative to air-breathing mice, carbogen or oxygen produced a small, and not always significant, increase in sensitivity (enhancement ratios < or = 1.15) in gut, lung and kidneys; however, in skin a dose enhancement of 1.2-1.3 was observed. The effect of nicotinamide in air, carbogen or oxygen was studied only in lung and gut. The drug produced variable but generally significant increases in radiosensitisation ( < or = 1.26) in all three gases. Relative to treatments in air, enhancement ratios for nicotinamide alone were usually slightly higher than those observed when either carbogen or oxygen were administered without the drug. With all three modifiers (i.e. oxygen, carbogen, nicotinamide alone or for the drug-gas combinations) there was no significant change in the enhancement ratios observed as the number of radiation dose fractions was varied.

CONCLUSIONS

Comparisons with fractionated X-ray studies done previously in rodent tumours indicate that a therapeutic benefit, relative to lung, gut and renal damage, would be observed with oxygen or carbogen alone but not with nicotinamide alone. The greatest gain would be achieved with the combination of carbogen and nicotinamide, with which a benefit was observed even relative to epidermal damage. These results indicate that some decrease in normal tissue tolerance could be observed when using these modifiers in clinical radiotherapy and, although small, the appropriate dose reductions should be considered; caution should be exercised especially when carbogen and nicotinamide are used in conjunction with the more radical accelerated schedules.

Toxicity of inhaled plutonium dioxide in beagle dogs

This study was conducted to determine the biological effects of inhaled 238PuO2 over the life spans of 144 beagle dogs. The dogs inhaled one of two sizes of monodisperse aerosols of 238PuO2 to achieve graded levels of initial lung burden (ILB). The aerosols also contained 169Yb to provide a gamma-ray-emitting label for the 238Pu inhaled by each dog. Excreta were collected periodically over each dog's life span to estimate plutonium excretion; at death, the tissues were analyzed radiochemically for plutonium activity. The tissue content and the amount of plutonium excreted were used to estimate the ILB. These data for each dog were used in a dosimetry model to estimate tissue doses. The lung, skeleton and liver received the highest alpha-particle doses, ranging from 0.16-68 Gy for the lung, 0.08-8.7 Gy for the skeleton and 0.18-19 for the liver. At death all dogs were necropsied, and all organs and lesions were sampled and examined by histopathology. Findings of non-neoplastic changes included neutropenia and lymphopenia that developed in a dose-related fashion soon after inhalation exposure. These effects persisted for up to 5 years in some animals, but no other health effects could be related to the blood changes observed. Radiation pneumonitis was observed among the dogs with the highest ILBs. Deaths from radiation pneumonitis occurred from 1.5 to 5.4 years after exposure. Tumors of the lung, skeleton and liver occurred beginning at about 3 years after exposure. Bone tumors found in 93 dogs were the most common cause of death. Lung tumors found in 46 dogs were the second most common cause of death. Liver tumors, which were found in 20 dogs but were the cause of death in only two dogs, occurred later than the tumors in bone and lung. Tumors in these three organs often occurred in the same animal and were competing causes of death. These findings in dogs suggest that similar dose-related biological effects could be expected in humans accidentally exposed to 238PuO2.

Long-term survival and symptom palliation in small primary bronchial carcinomas following treatment with intraluminal radiotherapy alone

Between April 1988 and December 1992, 37 patients with small, previously unirradiated, primary non-small cell carcinomas of the bronchus causing symptoms due to endobronchial disease were treated at the Christie Hospital, Manchester, with a single fraction of high dose rate intraluminal radiotherapy (ILT) using the microSelectron-HDR machine. Small primary (SP) lesions were defined as being less than 2 cm in diameter in a direction perpendicular to the central axis of the iridium-192 treatment source. Fifteen patients (41%) were treated to a dose of 15 Gy and 22 patients (59%) to 20 Gy at a distance of 1 cm from the central axis of the source. At 6 weeks following ILT, improvement in symptoms was seen in the following percentages of patients: haemoptysis 96%, pulmonary collapse 69%, cough 55% and dyspnoea 52%. The magnitude of improvement in these symptoms was largely maintained in patients surviving to 4 months and then 12 months post-ILT. Median actuarial survival was 709 days, 2-year survival 49.4% and 5-year survival 14.1%. Overall, there was no significant difference in survival after treatment with 20 Gy compared with 15 Gy at 1 cm. At the close of study, there were four patients still alive without disease recurrence with survivals of 38, 48, 49 and 63 months. All had had biopsy-proven squamous cell carcinomas and all had been treated with 20 Gy at 1 cm. Five patients died from massive haemoptysis as a terminal event at 4, 9, 9, 10 and 11 months post-ILT, well below the median survival for this group of patients. Again, all had been treated with 20 Gy as opposed to 15 Gy at 1 cm. Over the same time period, 287 patients with non-small cell carcinomas of more than 2 cm in diameter (large primary lesions, LP), were treated with a single fraction of ILT only, as their initial treatment. A consistently greater percentage of patients with SP lesions showed an improvement in the symptoms of haemoptysis and pulmonary collapse when compared with patients with LP lesions. Patients with LP lesions demonstrated a decreased actuarial survival when compared with SP lesions, with median survival being 156 days, 2-year survival 3.1% and no survivors beyond 39 months. This study demonstrates that, in patients with small endobronchial carcinomas a single fraction of ILT can give efficient palliation of symptoms and lead to long term disease-free survival, but that a dose of 20 Gy may be at the limit of bronchial radiation tolerance for a single dose technique employing a high dose rate source.

Damage and morbidity from pneumonitis after irradiation of partial volumes of mouse lung

PURPOSE

The aims of this study were to: (a) define the relationship of dose and volume irradiated to damage and morbidity in mouse lung, (b) determine the threshold volume for morbidity after partial lung irradiation; and (c) determine whether the response to radiation of mouse lung is independent of the region irradiated.

METHODS AND MATERIALS

C3Hf/Kam female mice were used in this study. The fractional volume of the lung to be irradiated was determined by two methods, weights and computed tomography (CT) scanning. Two experiments were performed to define the volume effect and to determine whether the response of the mouse lung to radiation was homogeneous. In the first experiment, single doses of x-rays ranging from 12 to 20 Gy were given to partial volumes of 84%, 70%, and 40% including the base, 50%, 33%, and 17% including the apex, to 43% in the middle, and to the sum of 57% as 17% in the apex and 40% in the base. In the second experiment, the same volumes of 50% and 70-75% in the apex and base of the lung were irradiated with single doses ranging from 12-19.25 Gy. Morbidity from radiation pneumonitis was quantitated by two end points, breathing rate and lethality between 12 and 32 weeks after irradiation. Damage was assessed by histopathological evidence of pneumonitis.

RESULTS

Clear well-defined dose-response curves were obtained for both breathing rate and lethality after all volumes irradiated. There was a clear volume-dependent shift of the dose-response curves for breathing rate and lethality at 28 weeks after irradiation, the end of the pneumonitis phase of damage, to higher doses compared with these data after whole-lung irradiation. In addition, the slopes of the dose-response curves for irradiation of partial lung volumes were more shallow compared to those after whole-lung irradiation. Increases in breathing rate correlated with lethality when the volume irradiated was equal to or greater than 50% of the reference volume. However, after irradiation of volumes smaller than 40%, breathing rate increases were not accompanied by death. A heterogeneous response of the mouse lung to radiation was observed in the first experiment and confirmed by the second experiment. For a given volume irradiated, the isoeffect dose was always less for the base than for the apex of the lung. The threshold volume for breathing rate changes was less than 17 and 40% when the irradiated volumes involved the apex and base, respectively. For lethality, the threshold volume was between 40 and 70% for the base and greater than 50% for the apex of the lung. Finally, damage as assessed by histological evidence of pneumonitis was observed in the irradiated area only.

CONCLUSIONS

(a) The volume effect was resolvable in mice, (b) the volume effect in mouse lung exhibits a clear threshold for morbidity, (c) the threshold volume for morbidity is dependent on the end point, (d) the response of mouse lung is heterogeneous, dependent on the site irradiated, and is always greater for the same volumes irradiated in the base than the apex, and, (e) histopathological damage does not always produce observable morbidity.