Expanded HILUS Trial: A Pooled Analysis of Risk Factors for Toxicity From Stereotactic Body Radiation Therapy of Central and Ultracentral Lung Tumors

PURPOSE

Stereotactic body radiation therapy for tumors near the central airways implies high-grade toxic effects, as concluded from the HILUS trial. However, the small sample size and relatively few events limited the statistical power of the study. We therefore pooled data from the prospective HILUS trial with retrospective data from patients in the Nordic countries treated outside the prospective study to evaluate toxicity and risk factors for high-grade toxic effects.

METHODS AND MATERIALS

All patients were treated with 56 Gy in 8 fractions. Tumors within 2 cm of the trachea, the mainstem bronchi, the intermediate bronchus, or the lobar bronchi were included. The primary endpoint was toxicity, and the secondary endpoints were local control and overall survival. Clinical and dosimetric risk factors were analyzed for treatment-related fatal toxicity in univariable and multivariable Cox regression analyses.

RESULTS

Of 230 patients evaluated, grade 5 toxicity developed in 30 patients (13%), of whom 20 patients had fatal bronchopulmonary bleeding. The multivariable analysis revealed tumor compression of the tracheobronchial tree and maximum dose to the mainstem or intermediate bronchus as significant risk factors for grade 5 bleeding and grade 5 toxicity. The 3-year local control and overall survival rates were 84% (95% CI, 80%-90%) and 40% (95% CI, 34%-47%), respectively.

CONCLUSIONS

Tumor compression of the tracheobronchial tree and high maximum dose to the mainstem or intermediate bronchus increase the risk of fatal toxicity after stereotactic body radiation therapy in 8 fractions for central lung tumors. Similar dose constraints should be applied to the intermediate bronchus as to the mainstem bronchi.

The solvent and treatment regimen of sodium selenite cause its effects to vary on the radiation response of human bronchial cells from tumour and normal tissues

Sodium selenite is often given to moderate the side effects of cancer therapy to enhance the cellular defence of non-cancerous cells. To determine whether sodium selenite during radiotherapy protects not only normal cells but also cancer cells, which would imply a reduction of the desired effect of irradiation on tumour during radiotherapy, the effect of the combined treatment of irradiation and sodium selenite was investigated. Human bronchial cells from carcinoma (A549) and normal tissue (BEAS-2B) were treated with sodium selenite and effects on growth and in combination with radiation on metabolic activity and cell cycle distribution were studied. The influence on radiosensitivity was determined via colony forming assays using different solvents of sodium selenite and treatment schedules. It was shown that sodium selenite inhibits growth and influences cell cycle distribution of both normal and tumour cells. Metabolic activity of normal cells decreased more rapidly compared to that of cancer cells. The influence of sodium selenite on radiation response depended on the different treatment schedules and was strongly affected by the solvent of the agent. It could be shown that the effect of sodium selenite on radiation response is strongly dependent on the respective experimental in vitro conditions and ranges from lead to an initially suspected but ultimately no real radioprotection to radiosensitizing up to no effect in one and the same cell line. This might be a reason for controversially described cell responses to radiation under the influence of sodium selenite in studies so far.

Rupture of Left Main Bronchus Associated with Radiotherapy-induced Bronchial Injury and Use of a Double-lumen Tube in Oesophageal Cancer Surgery

We report a case of rupture of the left main bronchus in a female patient with oesophageal carcinoma, who had received thoracic radiotherapy preoperatively. Endotracheal intubation was achieved with a left-sided double-lumen tube. After almost three hours of intubation and one and half hours of one-lung ventilation, bronchial injury was detected. Immediate surgical repair of the membranous part of the bronchus was undertaken, as well as completion of the oesophagectomy. Radiotherapy-induced damage to the bronchus was thought to have contributed to the rupture. The presentation, diagnosis and management of intraoperative bronchial rupture are discussed.

Cytotoxicity and genotoxicity of light emitted by incandescent, halogen, and LED bulbs on ARPE-19 and BEAS-2B cell lines

LED technology has the extraordinary ability to reduce energy consumption, constituting an economic and ecological advantage, so it is planned to replace incandescent, halogen and other inefficient bulbs for public and domestic lighting with LEDs. LEDs present specific spectral and energetic characteristics compared with those of other domestic light sources, so the potential risks for human health of these bulbs need to be explored. The aim of this study was to assess cytotoxicity and genotoxicity of light emitted by different commercial light bulbs: incandescent, halogen, and two LED bulbs with different correlated color temperatures. The evaluation was done on ARPE-19 as a specific cell model for eye toxicity and on BEAS-2B as a good cell model for toxicology tests. Light induced mainly cytotoxic effects on ARPE-19 and DNA damage on BEAS-2B, so different cell lines showed different biological responses. Moreover, our findings indicate that among the four bulbs, cold LED caused the highest cytotoxic effect on ARPE-19 and the highest genotoxic and oxidative effect on BEAS-2B. Cold LED is probably able to cause more cellular damage because it contains more high-energy radiations (blue). These results suggest that LED technology could be a safe alternative to older technologies, but the use of warm LED should be preferred to cold LED, which can potentially cause adverse effects on retinal cells.

BRONCHUS AND LUNG CANCER INCIDENCE IN POPULATION LIVING AROUND THE FORMER URANIUM MAINING AND MILING SITES

The indoor radon concentrations and lung cancer incidence in Eleshnitza village and Blagoevgrad district of Bulgaria were examined in the study reported here. The Eleshnitza was the second largest uranium mining and milling region of the country. The geometric mean of indoor radon concentration in Eleshnitza (465 Bq/m3) was higher than the geometric mean of Blagoevgrad district (78 Bq/m3). Retrospective analyses on lung cancer incidence, covering the period 1995-2012 have been shown the same trend. The results were suggestive of an existing relationship between the two variables. Possible effects attributable to age and gender on lung cancer incidence were examined and found to be significant.

Establishment of detailed respiratory tract model and Monte Carlo simulation of radon progeny caused dose

As radon is one of the most important natural radiation sources, its radiation hazard has always been a concern. α and β particles emitted by short-lived radioactive radon progeny nuclides could result in a high local dose and induce radiation damage to the respiratory tract. A detailed respiratory tract model needs to be built and dose distribution in the respiratory tract should be studied to reflect the characteristics of energy deposition caused by radon and its progeny. Therefore, in the present work, a dosimetric study was conducted on the respiratory tract and non-uniform dose distribution in the bronchial region was studied. First, a detailed voxel respiratory tract model was established based on the anatomic bronchial parameters of an adult Chinese male. The dimensional parameters of the tracheo-bronchial tree of an adult male adopted in ICRP Publication 66 (ICRP 1994 Human Respiratory Tract Model for Radiological Protection ICRP Publication 66 (Oxford: Pergamon)), featured by consecutive 16 generations of bronchi structures to express the irregular structure of the respiratory tract and the radiosensitive tissues in the bronchial region, were also built for dosimetric study. Then the deposition and clearance models recommended by ICRP were used to analyse the regional deposition and transfer in the respiratory tract, and a fluid dynamic simulation was used to obtain 3D distribution of radon progeny aerosol particles in the bronchial region. The result showed that the highest deposition fraction density occurs at the first and second generations of bronchi. Furthermore, the detailed voxel respiratory tract model along with the Monte Carlo method were used to obtain dose distribution in the BB region. It was found that the dose distribution in the respiratory tract is very non-uniform and the maximum voxel dose is about 30 times higher than the average voxel dose. The dose conversion factor (DCF) for lung in the home environment derived with the dosimetry method in the present work is 9.86 mSv·WLM^-1. Sensitivity analysis was performed for the parameters involved in the DCF calculation and it was found that the unattached fraction and breathing rate influence the DCF the most.

Endobronchial brachytherapy with curative intent: the impact of reference points setting according to the bronchial diameter

Endobronchial brachytherapy (EBB) is an effective treatment for endobronchial tumors. However, bronchial toxicity caused by over-irradiation remains problematic. To decrease bronchial toxicity, we developed a source-centralizing applicator for EBB. The purpose of the present study was to assess the efficacy and safety of EBB with varying reference dose points according to the bronchial diameter, using a source-centralizing applicator. We reviewed 15 patients with endobronchial carcinoma who were treated with curative intent using a combination of external beam radiotherapy (EBRT) and high-dose-rate EBB between 2005 and 2014. During each EBB session, we used a source-centralizing applicator that maintained the source-delivering catheter in the center of the bronchial lumen. Reference dose points were 5-7 mm from the source axis, depending on the bronchial diameter. The median radiation doses of EBRT and EBB were 40 Gy in 20 fractions and 18 Gy in 3 fractions, respectively. The median observation period was 36 months. The 3-year overall survival, progression-free survival and local control rates were 79%, 77% and 100%, respectively. Grade 2 radiation pneumonitis was observed in two cases. Bronchial toxicities, such as hemoptysis or the symptoms of chronic bronchitis, were not observed. EBB with varying reference dose points according to bronchial diameter, using a source-centralizing applicator, is a promising procedure that may be effective for tumor elimination and reducing toxicity to the bronchial wall.

Dosimetric impact of an air passage on intraluminal brachytherapy for bronchus cancer

The brachytherapy dose calculations used in treatment planning systems (TPSs) have conventionally been performed assuming homogeneous water. Using measurements and a Monte Carlo simulation, we evaluated the dosimetric impact of an air passage on brachytherapy for bronchus cancer. To obtain the geometrical characteristics of an air passage, we analyzed the anatomical information from CT images of patients who underwent intraluminal brachytherapy using a high-dose-rate ¹⁹²Ir source (MicroSelectron V2r®, Nucletron). Using an ionization chamber, we developed a measurement system capable of measuring the peripheral dose with or without an air cavity surrounding the catheter. Air cavities of five different radii (0.3, 0.5, 0.75, 1.25 and 1.5 cm) were modeled by cylindrical tubes surrounding the catheter. A Monte Carlo code (GEANT4) was also used to evaluate the dosimetric impact of the air cavity. Compared with dose calculations in homogeneous water, the measurements and GEANT4 indicated a maximum overdose of 5-8% near the surface of the air cavity (with the maximum radius of 1.5 cm). Conversely, they indicated a minimum overdose of ~1% in the region 3-5 cm from the cavity surface for the smallest radius of 0.3 cm. The dosimetric impact depended on the size and the distance of the air passage, as well as the length of the treatment region. Based on dose calculations in water, the TPS for intraluminal brachytherapy for bronchus cancer had an unexpected overdose of 3-5% for a mean radius of 0.75 cm. This study indicates the need for improvement in dose calculation accuracy with respect to intraluminal brachytherapy for bronchus cancer.

Effectiveness of bronchial thermoplasty in patients with severe refractory asthma: Clinical and histopathologic correlations

BACKGROUND

The effectiveness of bronchial thermoplasty (BT) has been reported in patients with severe asthma, yet its effect on different bronchial structures remains unknown.

OBJECTIVE

We sought to examine the effect of BT on bronchial structures and to explore the association with clinical outcome in patients with severe refractory asthma.

METHODS

Bronchial biopsy specimens (n = 300) were collected from 15 patients with severe uncontrolled asthma before and 3 months after BT. Immunostained sections were assessed for airway smooth muscle (ASM) area, subepithelial basement membrane thickness, nerve fibers, and epithelial neuroendocrine cells. Histopathologic findings were correlated with clinical parameters.

RESULTS

BT significantly improved asthma control and quality of life at both 3 and 12 months and decreased the numbers of severe exacerbations and the dose of oral corticosteroids. At 3 months, this clinical benefit was accompanied by a reduction in ASM area (median values before and after BT, respectively: 19.7% [25th-75th interquartile range (IQR), 15.9% to 22.4%] and 5.3% [25th-75th IQR], 3.5% to 10.1%, P < .001), subepithelial basement membrane thickening (4.4 μm [25th-75th IQR, 4.0-4.7 μm] and 3.9 μm [25th-75th IQR, 3.7-4.6 μm], P = 0.02), submucosal nerves (1.0 ‰ [25th-75th IQR, 0.7-1.3 ‰] immunoreactivity and 0.3 ‰ [25th-75th IQR, 0.1-0.5 ‰] immunoreactivity, P < .001), ASM-associated nerves (452.6 [25th-75th IQR, 196.0-811.2] immunoreactive pixels per mm² and 62.7 [25th-75th IQR, 0.0-230.3] immunoreactive pixels per mm², P = .02), and epithelial neuroendocrine cells (4.9/mm² [25th-75th IQR, 0-16.4/mm²] and 0.0/mm² [25th-75th IQR, 0-0/mm²], P = .02). Histopathologic parameters were associated based on Asthma Control Test scores, numbers of exacerbations, and visits to the emergency department (all P ≤ .02) 3 and 12 months after BT.

CONCLUSION

BT is a treatment option in patients with severe therapy-refractory asthma that downregulates selectively structural abnormalities involved in airway narrowing and bronchial reactivity, particularly ASM, neuroendocrine epithelial cells, and bronchial nerve endings.

Radon induced hyperplasia: effective adaptation reducing the local doses in the bronchial epithelium

There is experimental and histological evidence that chronic irritation and cell death may cause hyperplasia in the exposed tissue. As the heterogeneous deposition of inhaled radon progeny results in high local doses at the peak of the bronchial bifurcations, it was proposed earlier that hyperplasia occurs in these deposition hot spots upon chronic radon exposure. The objective of the present study is to quantify how the induction of basal cell hyperplasia modulates the microdosimetric consequences of a given radon exposure. For this purpose, computational epithelium models were constructed with spherical cell nuclei of six different cell types based on histological data. Basal cell hyperplasia was modelled by epithelium models with additional basal cells and increased epithelium thickness. Microdosimetry for alpha-particles was performed by an own-developed Monte-Carlo code. Results show that the average tissue dose, and the average hit number and dose of basal cells decrease by the increase of the measure of hyperplasia. Hit and dose distribution reveal that the induction of hyperplasia may result in a basal cell pool which is shielded from alpha-radiation. It highlights that the exposure history affects the microdosimetric consequences of a present exposure, while the biological and health effects may also depend on previous exposures. The induction of hyperplasia can be considered as a radioadaptive response at the tissue level. Such an adaptation of the tissue challenges the validity of the application of the dose and dose rate effectiveness factor from a mechanistic point of view. As the location of radiosensitive target cells may change due to previous exposures, dosimetry models considering the tissue geometry characteristic of normal conditions may be inappropriate for dose estimation in case of protracted exposures. As internal exposures are frequently chronic, such changes in tissue geometry may be highly relevant for other incorporated radionuclides.

Analysis of the miRNA-mRNA networks in malignant transformation BEAS-2B cells induced by alpha-particles

The aim of this study was to determine the toxicity induced by irradiation with alpha-particles on malignant transformation of immortalized human bronchial epithelial cells (BEAS-2B) using miRNA-mRNA networks. The expression of BEAS-2B cells was determined by measuring colony formation, mtDNA, mitochondrial membrane potential (MMP), and ROS levels. Changes in BEAS-2B cell gene expression were observed and quantified using microarrays that included an increase in 157 mRNA and 20 miRNA expression and a decrease in 77 mRNA and 48 miRNA. Bioinformatic software was used to analyze these different mRNA and miRNA, which indicated that miR-107 and miR-494 play an important role in alpha-particles-mediated cellular malignant transformation processes. The pathways related to systemic lupus erythematosus, cytokine-cytokine receptor interaction, MAPK signaling pathway, regulation of actin cytoskeleton, and cell adhesion molecules (CAMs) were stimulated, while those of ribosome, transforming growth factor (TGF)-beta signaling pathway, and metabolic pathways were inhibited. Data suggest that miRNA and mRNA play a crucial role in alpha-particles-mediated malignant transformation processes. It is worth noting that three target genes associated with lung cancer were identified and upregulated PEG 10 (paternally expressed gene 10), ARHGAP26, and IRS1.

Stochastic rat lung dosimetry for inhaled radon progeny: a surrogate for the human lung for lung cancer risk assessment

Laboratory rats are frequently used in inhalation studies as a surrogate for human exposures. The objective of the present study was therefore to develop a stochastic dosimetry model for inhaled radon progeny in the rat lung, to predict bronchial dose distributions and to compare them with corresponding dose distributions in the human lung. The most significant difference between human and rat lungs is the branching structure of the bronchial tree, which is relatively symmetric in the human lung, but monopodial in the rat lung. Radon progeny aerosol characteristics used in the present study encompass conditions typical for PNNL and COGEMA rat inhalation studies, as well as uranium miners and human indoor exposure conditions. It is shown here that depending on exposure conditions and modeling assumptions, average bronchial doses in the rat lung ranged from 5.4 to 7.3 mGy WLM(-1). If plotted as a function of airway generation, bronchial dose distributions exhibit a significant maximum in large bronchial airways. If, however, plotted as a function of airway diameter, then bronchial doses are much more uniformly distributed throughout the bronchial tree. Comparisons between human and rat exposures indicate that rat bronchial doses are slightly higher than human bronchial doses by about a factor of 1.3, while lung doses, averaged over the bronchial (BB), bronchiolar (bb) and alveolar-interstitial (AI) regions, are higher by about a factor of about 1.6. This supports the current view that the rat lung is indeed an appropriate surrogate for the human lung in case of radon-induced lung cancers. Furthermore, airway diameter seems to be a more appropriate morphometric parameter than airway generations to relate bronchial doses to bronchial carcinomas.

[Bronchial thermoplasty: a real advancement in the treatment of asthma]

New treatments are needed to improve the care of severe asthmatic patients. Bronchial thermoplasty aims to lessen the airway smooth muscles via the heating of bronchial walls by radiofrequency. The preliminary studies showed a good tolerance and some good efficacy. Randomized controlled trials have been undertaken on moderate to severe asthmatic patients, demonstrating an improvement in quality of life, rate of severe exacerbations and unscheduled medical visits. The main side-effects consist of asthma exacerbations, atelectasis and infections. Bronchial thermoplasty is an innovative treatment with good efficacy and acceptable tolerance for moderate to severe asthmatic patients. More studies are needed to better understand its mechanism of action and more clearly delineate the precise indications of this innovative technique.

Biophysical modelling of the effects of inhaled radon progeny on the bronchial epithelium for the estimation of the relationships applied in the two-stage clonal expansion model of carcinogenesis

There is a considerable debate between research groups applying the two-stage clonal expansion model for lung cancer risk estimation, whether radon exposure affects initiation and transformation or promotion. The aim of the present study is to quantify the effects of radon progeny on these stages with biophysical models. For this purpose, numerical models of mutation induction and clonal growth were applied in order to estimate how initiation, transformation and promotion rates depend on tissue dose rate. It was found that rates of initiation and transformation increase monotonically with dose rate, whereas effective promotion rate decreases with time but increases sublinearly with dose rate. Despite the uncertainty of results due to the lack of experimental data, present study suggests that effects of radon exposure on both mutational events and clonal growth are significant and should be considered in mechanistic models of carcinogenesis applied for analysing epidemiological data.

[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.

Attempted validation of ICRP 30 and ICRP 66 respiratory models

The validation of human biological models for inhaled radionuclides is nearly impossible. Requirements for validation are: (1) the measurement of the relevant human tissue data and (2) valid exposure measurements over the interval known to apply to tissue uptake. Two lung models, ICRP 30(1) and ICRP 66(2), are widely used to estimate lung doses following acute occupational or environmental exposure. Both ICRP 30 and 66 lung models are structured to estimate acute rather than chronic exposure. Two sets of human tissue measurements are available: (210)Po accumulated in tissue from inhaled cigarettes and ingested in diet and airborne global fallout (239,240)Pu accumulated in the lungs from inhalation. The human tissue measurements include pulmonary and bronchial tissue in smokers, ex-smokers and non-smokers analysed radiochemically for (210)Po, and pulmonary, bronchial and lymph nodes analysed for (239,240)Pu in lung tissue collected by the New York City Medical Examiner from 1972 to 1974. Both ICRP 30 and 66 models were included in a programme to accommodate chronic uptake. Neither lung model accurately described the estimated tissue concentrations but was within a factor of 2 from measurements. ICRP 66 was the exception and consistently overestimated the bronchial concentrations probably because of its assumption of an overly long 23-d clearance half-time in the bronchi and bronchioles.

Radon-induced reduced apoptosis in human bronchial epithelial cells with knockdown of mitochondria DNA

Radon and radon progeny inhalation exposure are recognized to induce lung cancer. To explore the role of mitochondria in radon-induced carcinogenesis in humans, an in vitro partially depleted mitochondrial DNA (mtDNA) cell line (ρ-) was generated by treatment of human bronchial epithelial (HBE) cells (ρ+) with ethidium bromide (EB). The characterization of ρ- cells indicated the presence of dysfunctional mitochondria and might thus serve a reliable model to investigate the role of mitochondria. In a gas inhalation chamber, ρ- and ρ+ cells were exposed to radon gas produced by a radium source. Results showed that apoptosis was significantly increased both in ρ- and ρ+ cells irradiated by radon. Moreover, apoptosis in ρ- cells showed a lower level than in ρ+ cells. Radon was further found to depress mitochondrial membrane potential (MMP) of HBE cells with knockdown mtDNA. Production of reactive oxygen species (ROS) was markedly elevated both in ρ- and ρ+ cells exposed to radon. The distribution of phases of cell cycle was different in ρ- compared to ρ+ cells. Radon irradiation induced a rise in G2/M and decrease in S phase in ρ+ cells. In ρ- cells, G1, G2/M, and S populations remained similar to cells exposed to radon. In conclusion, radon-induced changes in ROS generation, MMP and cell cycle are all attributed to reduction of apoptosis, which may trigger and promote cell transformation, leading to carcinogenesis. Our study indicates that the use of the ρ- knockdown mtDNA HBE cells may serve as a reliable model to study the role played by mitochondria in carcinogenic diseases.

Bronchial thermoplasty

Even with the use of maximum pharmacological treatment, asthma still remains uncontrolled in some cases. For such cases of uncontrolled asthma, a novel therapy--Bronchial Thermoplasty (BT)--has shown some promising results over the past few years. BT is application of controlled radiofrequency heat via catheter inserted through a flexible bronchoscope, to the bronchial walls. It reduces the smooth muscle mass in bronchial wall and thus results in decreased contractility. Three major trials of BT show that it does not cause any improvement in FEV1. However, BT causes improvement the quality of life and decreases the future exacerbations and emergency hospital visits due to asthma. But the benefit observed was too small to be clinically significant. Follow up (two to five years) results of these BT trials did not show any significant long-term adverse event related to BT. However, further independent large randomized controlled trials and results of application of BT in real hospital settings are needed to define its role in asthma management.

Effect of site-specific bronchial radon progeny deposition on the spatial and temporal distributions of cellular responses

Inhaled short-lived radon progenies may deposit in bronchial airways and interact with the epithelium by the emission of alpha particles. Simulation of the related radiobiological effects requires the knowledge of space and time distributions of alpha particle hits and biological endpoints. Present modelling efforts include simulation of radioaerosol deposition patterns in a central bronchial airway bifurcation, modelling of human bronchial epithelium, generation of alpha particle tracks, and computation of spatio-temporal distributions of cell nucleus hits, cell killing and cell transformation events. Simulation results indicate that the preferential radionuclide deposition at carinal ridges plays an important role in the space and time evolution of the biological events. While multiple hits are generally rare for low cumulative exposures, their probability may be quite high at the carinal ridges of the airway bifurcations. Likewise, cell killing and transformation events also occur with higher probability in this area. In the case of uniform surface activities, successive hits as well as cell killing and transformation events within a restricted area (say 0.5 mm(2)) are well separated in time. However, in the case of realistic inhomogeneous deposition, they occur more frequently within the mean cycle time of cells located at the carinal ridge even at low cumulative doses. The site-specificity of radionuclide deposition impacts not only on direct, but also on non-targeted radiobiological effects due to intercellular communication. Incorporation of present results into mechanistic models of carcinogenesis may provide useful information concerning the dose-effect relationship in the low-dose range.

Prediction of lung cancer risk for radon exposures based on cellular alpha particle hits

To explore the role of the multiplicity of cellular hits by radon progeny alpha particles for lung cancer incidence, the number of single and multiple alpha particle hits were computed for basal and secretory cells in the bronchial epithelium of human airway bifurcations. Hot spots of alpha particle hits were observed at the branching points of bronchial airway bifurcations. The effect of single and multiple alpha particle intersections of bronchial cells during a given exposure period, selected from a Poisson distribution, on lung cancer risk were simulated by a transformation frequency--tissue response model, based on experimentally observed cellular transformation and survival functions. Calculations of lung cancer risk at low radon exposure levels suggest that single hits produce a linear-dose response relationship, while the superposition of single and increasing multiple hits at higher exposure levels may also be approximated by a quasi-linear dose-effect curve. The simulations predict a carcinogenic enhancement effect for radon progeny accumulations at bifurcation branching sites, which may increase current risk estimates.

Direct and bystander effects induced by scattered radiation generated during penetration of radiation inside a water-phantom

In this study, the dose distribution of photon (6 MV) and electron (22 MeV) radiation in a water-phantom was compared with the frequency of apoptotic and micronucleated cells of two human cell lines (BEAS-2B normal bronchial epithelial cells and A549 lung cancer epithelial cells). Formation of micronuclei and apoptotic-like bodies was evaluated by the cytokinesis-block micronucleus test. Measurements were performed for five different phantom depths (3-20 cm). Irradiated cells were placed in a water-phantom in three variants: directly on the axis in the beam, under shielding (only in photon radiation) and outside the beam field. The results reveal a discrepancy between the distribution of physical dose at different depths of the water-phantom and biological effects. This discrepancy is of special significance in case of cells irradiated at a greater depth or placed outside the field and under shield during the exposure to radiation. The frequency of cytogenetic damage was higher than the expected value based on the physical dose received at different depths. Cells placed outside the beam axis were exposed to scattered radiation at very low doses, so we tested if bystander effects could have had a role in the observed discrepancy between physical radiation dose and biological response. We explored this question by use of a medium-transfer technique in which medium (ICM-irradiation conditioned medium) from irradiated cells was transferred to non-irradiated (bystander) cells. The results indicate that when cells were incubated in ICM transferred from cells irradiated at bigger depths or from cells exposed outside the radiation field, the number of apoptotic and micronucleated cells was similar to that after direct irradiation. This suggests that these damages are caused by factors released by irradiated cells into the medium rather than being induced directly in DNA by X-rays. Evaluation of biological effects of scattered radiation appears useful for clinical practice.

Cellular burdens and biological effects on tissue level caused by inhaled radon progenies

In the case of radon exposure, the spatial distribution of deposited radioactive particles is highly inhomogeneous in the central airways. The object of this research is to investigate the consequences of this heterogeneity regarding cellular burdens in the bronchial epithelium and to study the possible biological effects at tissue level. Applying computational fluid and particle dynamics techniques, the deposition distribution of inhaled radon daughters has been determined in a bronchial airway model for 23 min of work in the New Mexico uranium mine corresponding to 0.0129 WLM exposure. A numerical epithelium model based on experimental data has been utilised in order to quantify cellular hits and doses. Finally, a carcinogenesis model considering cell death-induced cell-cycle shortening has been applied to assess the biological responses. Present computations reveal that cellular dose may reach 1.5 Gy, which is several orders of magnitude higher than tissue dose. The results are in agreement with the histological finding that the uneven deposition distribution of radon progenies may lead to inhomogeneous spatial distribution of tumours in the bronchial airways. In addition, at the macroscopic level, the relationship between cancer risk and radiation burden seems to be non-linear.

Probability of bystander effect induced by alpha-particles emitted by radon progeny using the analytical model of tracheobronchial tree

Radiation-induced biological bystander effects have become a phenomenon associated with the interaction of radiation with cells. There is a need to include the influence of biological effects in the dosimetry of the human lung. With this aim, the purpose of this work is to calculate the probability of bystander effect induced by alpha-particle radiation on sensitive cells of the human lung. Probability was calculated by applying the analytical model cylinder bifurcation, which was created to simulate the geometry of the human lung with the geometric distribution of cell nuclei in the airway wall of the tracheobronchial tree. This analytical model of the human tracheobronchial tree represents the extension of the ICRP 66 model, and follows it as much as possible. Reported probabilities are calculated for various targets and alpha-particle energies. Probability of bystander effect has been calculated for alpha particles with 6 and 7.69 MeV energies, which are emitted in the (222)Rn chain. The application of these results may enhance current dose risk estimation approaches in the sense of the inclusion of the influence of the biological effects.

Lung dosimetry for inhaled radon progeny in smokers

Cigarette smoking may change the morphological and physiological parameters of the lung. Thus the primary objective of the present study was to investigate to what extent these smoke-induced changes can modify deposition, clearance and resulting doses of inhaled radon progeny relative to healthy non-smokers (NSs). Doses to sensitive bronchial target cells were computed for four categories of smokers: (1) Light, short-term (LST) smokers, (2) light, long-term (LLT) smokers, (3) heavy, short-term (HST) smokers and (4) heavy, long-term (HLT) smokers. Because of only small changes of morphological and physiological parameters, doses for the LST smokers hardly differed from those for NSs. For LLT and HST smokers, even a protective effect could be observed, caused by a thicker mucus layer and increased mucus velocities. Only in the case of HLT smokers were doses higher by about a factor of 2 than those for NSs, caused primarily by impaired mucociliary clearance, higher breathing frequency, reduced lung volume and airway obstructions. These higher doses suggest that the contribution of inhaled radon progeny to the risk of lung cancer in smokers may be higher than currently assumed on the basis of NS doses.

Screening of differential expressive genes in murine cells following radon exposure

This study was designed to construct and identify the subtracted cDNA library in peripheral blood cells of BALB/c mice and tracheal-bronchial epithelial cells of Wistar rats following exposure to radon inhalation. Two groups of the animals were exposed in a radon chamber at an accumulative dose of 100 WLM, while control animals were housed in a room at a background dose of 1 WLM. To construct a subtracted cDNA library enriched with differentially expressed genes, the SMART technique and suppression subtractive hybridization (SSH) assay were performed. The obtained forward and reverse cDNA fragments were directly inserted into a pMD-18 vector and transformed into Escherichia coli JM109. In total, 593 white bacterial clones were selected from both forward- and reverse-subtracted libraries. Among them, 81 clones were chosen for their differential expressions based on reverse Northern blot. Portions of these cDNA clones were also verified by a quantitative real-time polymerase chain reaction (PCR). The screening resulted in 14 upregulative and 8 downregulative known function/annotation genes, which were revealed to be functionally related to cell proliferation, cell oxidative and DNA damage, apoptosis, and tumor promotion. Access numbers were obtained from the GenBank for 11 unknown expressed sequence tags (EST). Analysis of biological roles of these cDNA fragments may provide further insight into mechanisms underlying adverse molecular events induced by high-dose radon exposure.

Radon and leukemia in the Danish study: another source of dose

An epidemiologic study of childhood leukemia in Denmark (2,400 cases; 6,697 controls) from 1968 to 1994 suggested a weak, but statistically significant, association of residential radon exposure and acute childhood lymphoblastic leukemia (ALL). The Danish study estimated a relative risk (RR) = 1.56 (95% CI, 1.05-2.30) for a cumulative exposure of 1,000 Bq m-3 y. For an exposure duration of 10 y their RR corresponds to a radon concentration of 100 Bq m-3. There are two dose pathways of interest where alpha particles could damage potential stem cells for ALL. One is the alpha dose to bone marrow, and two is the dose to bronchial mucosa where an abundance of circulating lymphocytes is found. Compared with an exposure of about 1 mSv y-1 from natural external background, radon and decay products contribute an additional 10 to 60% to the bone marrow equivalent dose. The other pathway for exposure of T (or B) lymphocytes is within the tracheobronchial epithelium (BE). Inhaled radon decay products deposit on the relatively small area of airway surfaces and deliver a significant dose to the nearby basal or mucous cells implicated in human lung cancer. Lymphocytes are co-located with basal cells and are half as abundant. Using a 10-y exposure to 100 Bq m-3, our dose estimates suggest that the equivalent dose to these lymphocytes could approach 1 Sv. The relatively high dose estimate to lymphocytes circulating through the BE, potential precursor cells for ALL, provides a dose pathway for an association.

H2AX phosphorylation and kinetics of radiation-induced DNA double strand break repair in human primary thyrocytes

BACKGROUND

Papillary thyroid carcinoma (PTC) represents the most frequent thyroid neoplasia and is associated with radiation exposure. A consistent proportion of PTC is characterized by chromosome rearrangements producing RET and TRK oncogenes, but the mechanisms underlying the thyrocyte propensity to such alterations are poorly understood. Diminished capacity of thyrocytes to repair radiation-induced DNA double strand breaks (DSBs) might play a role in chromosome rearrangements; however, this question has not been fully addressed due to the lack of physiologically relevant experimental models.

METHODS

Several normal human thyroid primary cultures were produced and characterized for their capacity to repair the DNA DSBs induced by ionizing radiation. For comparison, normal human bronchial epithelial cells were used. We employed the gammaH2AX foci assay; counts were determined at different time points after irradiation.

RESULTS

All the thyrocyte samples analyzed showed similar DNA DSBs induction. The rate of gammaH2AX foci clearance was homogenous, showing only small differences among samples.

CONCLUSION

This work reports the first characterization of DNA DSB repair in human primary thyrocytes, a relevant clinical model for thyroid carcinogenesis, and represents an important step toward dissection of the link between DNA DSB repair and thyroid-specific oncogenic rearrangements.

Radon progeny microdosimetry in human and rat bronchial airways: the effect of crossfire from the alveolar region

The objectives of the present study were (1) to present a comprehensive analysis of the microdosimetric quantities in both human and rat bronchial airways and (2) to assess the contribution of the crossfire alpha particles emitted from the alveolar region to bronchial absorbed doses. Hit frequencies, absorbed doses and critical microdosimetric quantities were calculated for basal and secretory cell nuclei located at different depths in epithelial tissue for each bronchial airway generation for defined exposure conditions. Total absorbed doses and hit frequencies were slightly higher in rat airways than in corresponding human airways. This confirms the a priori assumption in rat inhalation experiments that the rat lung is a suitable surrogate for the human lung. While the contribution of crossfire alpha particles is insignificant in the human lung, it can reach 33% in peripheral bronchiolar airways of the rat lung. The latter contribution may even further increase with increasing alveolar 214Po activities. Hence, the observed prevalence of tumors in the bronchiolar region of the rat lung may partly be attributed to the high-linear energy transfer crossfire alpha particles.

[A case of resection of esophageal cancer infiltrating the left main bronchus following preoperative chemo-radiotherapy and resection of metachronous lung metastasis]

We herein report a case of T4 esophageal carcinoma, which was resected after chemo-radiation therapy. In addition, the metachronous lung metastasis was also resected. A 59-year-old female with esophageal carcinoma, which invaded the left main bronchus, underwent chemo-radiation therapy (the combination of systemic chemotherapy of 5-FU/CDDP and external radiation therapy) from January 2004. After the therapy, although the imaging showed a downstaging of esophageal carcinoma, a severe esophageal stricture appeared with ingestion defective. So hyper-alimentation was performed. After the state of nutrition was improved, esophagectomy was performed on March 2004 without a complication. Histopathological study revealed that no viable cells remained. Nine months after esophagectomy, chest CT scan revealed that a solitary pulmonary tumor appeared in S6 of the right. The solitary tumor enlarged gradually. On August 2005, a surgical resection for the solitary pulmonary tumor was performed. Histopathologically, the lesion was compatible for metastasis from esophageal carcinoma. The patient is alive without recurrence more than 23 months after the last surgery.

TLR4 polymorphisms mediate impaired responses to respiratory syncytial virus and lipopolysaccharide

Severe bronchiolitis following respiratory syncytial virus (RSV) infection occurs in only a small subset of infected infants and the basis for variations in disease severity is not understood. Innate immune responses to RSV are mediated by TLR-4, and the (299)Gly and (399)Ile alleles of the TLR4 gene have been linked epidemiologically with increased severity of RSV disease in children. We hypothesized that cellular immune responses to RSV mediated by these variant forms of the receptor are defective relative to responses mediated via the common form of the receptor. Human bronchial epithelial cells were transfected with TLR4 constructs encoding the common TLR4 gene sequence ((299)Asp/(399)Thr), or the (299)Gly or (399)Ile alleles, and cytokine responses to in vitro RSV challenge were analyzed in the different transfected cells. Follow-up studies compared RSV-induced responses in PBMC from children expressing these same TLR4 genotypes. Human bronchial epithelial expressing (299)Gly or (399)Ile displayed normal levels of intracellular TLR4 but failed to efficiently translocate the receptor to the cell surface. This was associated with reduced NF-kappaB signaling post-TLR4 engagement, reduced production of IFNs, IL-8, IL-10, IL-12p35, IL-18, and CCL8, and the absence of acute-phase TNF-alpha. These findings were mirrored by blunted PBMC responses to RSV in children expressing the same TLR4 variants. Compromised first-line defense against RSV at the airway-epithelial surface of children expressing these TLR4 variants may thus confer increased susceptibility to severe infections with this virus.

[Efficiency of a combination of haloaerosols and helium-neon laser in the multimodality treatment of patients with bronchial asthma]

A hundred and thirty-eight patients with infection-dependent bronchial asthma, including 73 with moderate persistent asthma and 65 with severe persistent one, were examined. Four modes of a combination of traditional (drug) therapy (DT) and untraditional (halotherapy (HT) and endobronchial helium-neon laser irradiation (ELI) one were used. The efficiency of the treatment performed was evaluated, by determining the time course of clinical symptoms of the disease on the basis of scores of their magnitude and the patients' condition. The findings indicated that in moderate persistent asthma, both HT and ELI in combination with DT exerted an equal therapeutic effect, which provided a good and excellent condition in 83.3% of cases. In severe persistent asthma, such a condition was achieved in 93.75% of cases only when multimodality treatment involving DT, HT, and ELI had been performed.

Assessment and prevention of radioactive risk due to 222Radon on University Premises in Genoa, Italy

From October 2004 to September 2005, Radon222 activity in high-risk indoor spaces used by employees and students at the University of Genoa was measured with CR-39 nuclear track detectors. The mean concentration in winter (78.9 Bq/m3 +/- 74.92 S.D.) was low in relation to the microenvironment considered. When data were broken down by type and location of the spaces, no significant differences were found, despite the fact that the Genoa conurbation lies on soil of variable geological composition. The dose absorbed by employees was 0.42 mSv/year, with a relative risk of 4.2/1000 cases of Radon-related lung cancer. The dose absorbed by students was 0.28 mSv/year, with a relative risk of 2.5/1000 cases of Radon-related lung cancer. The level of radon activity detected never exceeded the limit of 500 Bq/m3 established by Italian law. Nevertheless, the value of the compound uncertainty index suggested that the real level of Radon contamination could have exceeded 400 Bq/m3 in selected spaces, a value requiring annual concentration tests.

Comparison of dose conversion factors for radon progeny from the ICRP 66 regional model and an airway tube model of tracheo-bronchial tree

Current epidemiological approaches to radon dosimetry yield a dose conversion factor (DCF) of 4 mSv WLM(-1) while the dosimetric approaches give a value closer to 13 mSv WLM(-1). The present study investigated whether the application of compartment models for the bronchial (BB) and bronchiolar (bb) regions, rather than more anatomically realistic airway tube models, has brought the dosimetric DCF to the higher values. The airway tube model of the tracheo-bronchial tree was used to calculate the effective dose per unit radon exposure. All other elements of the human respiratory tract from the reports of the ICRP or NRC were adopted. A dosimetric derivation of the radon DCF using the airway tube model yielded a value of 14.2 mSv WLM(-1). This value is slightly larger than, but not significantly different from, the result obtained through the ICRP 66 approach. It is concluded that utilization of the airway tube model instead of the regional ICRP 66 compartmental model cannot reconcile the gap between dose conversion factors derived from epidemiological and dosimetric approaches.

Radiation-induced narrowing of the tracheobronchial tree: An in-depth analysis

PURPOSE

Symptomatic narrowing of the tracheobronchial tree is not a common clinical problem after conventional-dose external beam radiation therapy but has been described when higher doses are utilized. This in-depth study quantifies changes in the caliber of the trachea and mainstem bronchi after high-dose external beam radiation therapy (EBRT).

METHODS AND MATERIALS

As part of an IRB-approved prospective clinical trial to assess for radiation-induced lung injury, patients with thoracic malignancies had pre- and serial post-RT CT scans in the radiation oncology department. This report focuses on 18 enrolled patients who received high-dose (> or = 73.6 Gy) EBRT for NSCLC. The caliber of the trachea, right mainstem bronchus, and left mainstem bronchus were measured utilizing three-dimensional coordinates in axial and coronal planes such that multiple measurements were made of each structure. The decrease in airway caliber was tested for significance using a one-sided Wilcoxon matched-pairs signed-ranks test. The correlation between airway caliber changes, dose, and follow-up interval was tested using the Spearman rank correlation coefficient and the effect of chemotherapy on airway narrowing was evaluated with a one-sided exact Wilcoxon rank sum test.

RESULTS

There was no significant narrowing of the trachea for all dose and time points. There were significant decreases in the caliber of both mainstem bronchi on axial measurements (p = 0.07 and 0.005 for right and left mainstem bronchi, respectively). Decrease in airway caliber ranged from 6 to 57% and appeared to be dose dependent (p = 0.08), progressed with increasing time post-RT (p = 0.04), and was worse in patients who also received chemotherapy (p = 0.04).

CONCLUSION

High-dose EBRT (> or = 73.6 Gy) appears to cause narrowing of the mainstem bronchi as early as 3 months post radiation therapy. Additional study is needed to assess the impact of such narrowing on RT-induced pulmonary symptoms.

Cyclooxygenase-2 as a signaling molecule in radiation-induced bystander effect

Radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation in that extranuclear and extracellular effects may also contribute to the final biological consequences of exposure to low doses of radiation. Evidence suggests that targeted cytoplasmic irradiation results in mutation in the nucleus of the "hit" cells and that cells, which are not directly hit by an alpha particle, whether nuclear or cytoplasm, but are in the vicinity of one that does get hit, contribute to the genotoxic response of the cell population. Although radiation-induced bystander effects have been well documented in a variety of biological systems, the mechanism is not known. Using the Columbia University charged particle beam in conjunction with a novel strip dish design, we showed recently that the cyclooxygenase-2 (COX-2) signaling cascade plays an essential role in the bystander process. Treatment of bystander cells with NS-398, which suppresses COX-2 activity, significantly reduced the bystander effect as well as the induction of the mitogen-activated protein kinase (MAPK) pathways. These results provided the first evidence that the COX-2-related pathway, which is essential in mediating cellular inflammatory responses, is the critical signaling link for the bystander phenomenon. A better understanding of the cellular and molecular mechanisms of the bystander phenomenon together with evidence of their occurrence in vivo will allow us to formulate a more accurate model in assessing the health effects of low doses of ionizing radiation.

[State of broncho-pulmonary system in liquidators of Chernobyl power accident consequences]

Liquidators of Chernobyl power accident consiquences were subjected to simultaneous external gamma-beta radiation and inhalation of particles containing radionuclides aerosols, nonradiation toxic chemicals and dust. Typical defects of medical examination of liquidators were seen: sending people with pulmonary diseases to post-accident work, erroneous interpretation of the disease severity with underestimation of previous occupational history and nonradiation factors deteriorating the case.

Alpha-hit, cellular dose, cell transformation and inactivation probability distributions of radon progenies in the bronchial epithelium

A fluid dynamics based model has been used to determine the deposition patterns of inhaled radon daughters in a realistic approach of the bronchial airway geometry. The interaction of the emitted alpha particles with epithelial cells has been analyzed by applying a complex hit probability model (Bronchial Alpha Hit Model). The biological response of the hit cells has been calculated by the Probability-Per-Unit-Track-Length Model, which relates the probability of a specific biological effect to the track length of alpha particles as a function of the particles' LET. The models mentioned above form a complex lung-radon interaction description. The calculations indicate that compared to the average values the transformation and cell killing probabilities are higher at bronchial carinal ridges. In addition, a considerable number of cells possessing a not negligible transformation and cell killing probabilities can also be found in the outer sides of the central zone.

Modelling the effect of non-uniform radon progeny activities on transformation frequencies in human bronchial airways

The effects of radiological and morphological source heterogeneities in straight and Y-shaped bronchial airways on hit frequencies and microdosimetric quantities in epithelial cells have been investigated previously. The goal of the present study is to relate these physical quantities to transformation frequencies in sensitive target cells and to radon-induced lung cancer risk. Based on an effect-specific track length model, computed linear energy transfer (LET) spectra were converted to corresponding transformation frequencies for different activity distributions and source-target configurations. Average transformation probabilities were considerably enhanced for radon progeny accumulations and target cells at the carinal ridge, relative to uniform activity distributions and target cells located along the curved and straight airway portions at the same exposure level. Although uncorrelated transformation probabilities produce a linear dose-effect relationship, correlated transformations first increase depending on the LET, but then decrease significantly when exceeding a defined number of hits or cumulative exposure level.

Management of Oropharyngeal and Tracheobronchial Secretions in Patients with Neurologic Disease

BACKGROUND

Neurologic disorders may impair the normal clearance of secretions. Effective palliation requires the management of excessive oral, pharyngeal and/or tracheobronchial secretions. This requires an understanding of underlying mechanisms and familiarity with the many available medical and surgical treatment options.

OBJECTIVES

The authors intend to review the relevant anatomy and physiology along with the available medical, surgical and physical therapies available to treat this commonly encountered problem.

DESIGN

A review of current management and the supporting literature.

CONCLUSIONS

Clinicians have many effective therapeutic options to choose from when managing the excessive oral, pharyngeal and/or tracheobronchial secretions caused by neurologic disorders. Treatment choices that are predicated upon pathophysiologic causes and patient status are the most likely to succeed.

Cell Cycle Effects of Radiation on Human Bronchial Epithelium and Lung Carcinoma Cells in Monolayer Cultures and a Three-Dimensional Co-culture System

The aim of this study was to investigate whether the three-dimensional structure of the bronchial tissue and the contact of non-malignant with malignant cells influence the effectiveness of radiotherapy. Monolayer cultures of cells of the human bronchial epithelial cell line BEAS 2B, monolayer co-cultures of BEAS 2B cells and cells of the GFP-transfected lung carcinoma cell line EPLC 32M1, organ cultures of human bronchial epithelium, and organ co-cultures with EPLC 32M1 cells were irradiated with 10 Gy, and the DNA content was analyzed using flow cytometry. In non-malignant epithelial cells, BEAS 2B monolayer cultures without tumor cells were highly radiosensitive. However, contact with tumor cells in monolayer co-cultures markedly reduced radiosensitivity. Non-malignant cells in three-dimensional organ cultures and organ co-cultures with tumor cells showed moderate radiosensitivity. In EPLC 32M1 tumor cells, proliferation was increased without irradiation when the cells were in contact with epithelial cells in both organ and monolayer co-cultures. Radiosensitivity was higher in organ co-cultures than in monolayer cultures and monolayer co-cultures. These data indicate that organ co-cultures in combination with flow cytometry allow investigation of the effects of radiation in an in vivo-like environment and that both the spatial organization and the interaction of non-malignant and tumor cells are crucial for the effectiveness of radiotherapy.

Lung radiofrequency ablation with and without bronchial occlusion: experimental study in porcine lungs

PURPOSE

This study was undertaken to compare the thermal lesion volumes in normal pig lungs when radiofrequency (RF) ablation is performed with and without airway occlusion.

MATERIALS AND METHODS

RF ablation was performed in six pigs. A straight 17-gauge internally cooled-tip electrode with a 2-cm exposed tip was inserted into the center of the lower lobe of the lung under biplane fluoroscopic guidance. In each animal, RF ablation was performed for 12 minutes with balloon occlusion of the main bronchus in one lung and without balloon occlusion in the contralateral lung. The tissue temperature around the electrode tip was measured immediately after RF application. The volumes of the thermal lesions were compared by histologic examination of the groups of lungs ablated with and without airway occlusion.

RESULTS

Tissue temperature was significantly higher in the bronchial occlusion group than in the group with normal ventilation (51 degrees C +/- 7 vs. 44 degrees C +/- 2; P < .05). RF ablation with bronchial occlusion resulted in the creation of a significantly greater thermal lesion volume compared with RF ablation with normal ventilation (6,535 mm(3) +/- 1,114 vs 3,368 mm(3) +/- 676; P < .03).

CONCLUSION

Prevention of ventilation in the normal swine lung via bronchial balloon occlusion during RF ablation increases the thermal ablation lesion volume, suggesting that active ventilation is a significant cause of in vivo heat loss.

An unusual cause of breathlessness after lobectomy for lung cancer

Localized bronchomalacia as a cause of breathlessness after lobectomy is an unusual complication. This condition was diagnosed with bronchoscopy and delineated by spiral computed tomographic scan. Stenting the lesion resulted in a successful outcome.

The bronchiolar epithelium as a prominent source of pro-inflammatory cytokines after lung irradiation

PURPOSE

To study in detail the temporal and spatial release of the pro-inflammatory cytokines tumor necrosis factor alpha, interleukin (IL)-1alpha, and IL-6 in the lung tissue of C57BL/6 mice after thoracic irradiation with 12 Gy.

METHODS AND MATERIALS

C57BL/6J mice were exposed to either sham irradiation or a single fraction of 12 Gy delivered to the thorax. Treated and sham-irradiated control mice were killed at 0.5 h, 1 h, 3 h, 6 h, 12 h, 24 h, 48 h, 72 h, 1 week, 2 weeks, 4 weeks, 8 weeks, 16 weeks, and 24 weeks post-irradiation (p.i.). Real-time multiplex reverse transcriptase polymerase chain reaction was established to evaluate the relative messenger RNA (mRNA) expression of TNF-alpha, IL-1alpha, and IL-6 in the lung tissue of the mice (compared with nonirradiated lung tissue). Immunohistochemical detection methods (alkaline phosphatase anti-alkaline phosphatase, avidin-biotin-complex [ABC]) and automated image analysis were used to quantify the protein expression of TNF-alpha, IL-1alpha, and IL-6 in the lung tissue (percentage of the positively stained area).

RESULTS

Radiation-induced release of the pro-inflammatory cytokines TNF-alpha, IL-1alpha, and IL-6 in the lung tissue was detectable within the first hours after thoracic irradiation. We observed statistically significant up-regulations for TNF-alpha at 1 h p.i. on mRNA (4.99 +/- 1.60) and at 6 h p.i. on protein level (7.23% +/- 1.67%), for IL-1alpha at 6 h p.i. on mRNA (11.03 +/- 0.77) and at 12 h p.i. on protein level (27.58% +/- 11.06%), for IL-6 at 6 h p.i. on mRNA (6.0 +/- 3.76) and at 12 h p.i. on protein level (7.12% +/- 1.93%). With immunohistochemistry, we could clearly demonstrate that the bronchiolar epithelium is the most prominent source of these inflammatory cytokines in the first hours after lung irradiation. During the stage of acute pneumonitis, the bronchiolar epithelium, as well as inflammatory cells in the lung interstitium, produced high amounts of TNF-alpha (with the maximal value at 4 weeks p.i.: 9.47% +/- 1.78%), IL-1alpha (with the peak value at 8 weeks p.i.: 14.76% +/- 7.77%), and IL-6 (with the peak value at 8 weeks p.i.: 4.28% +/- 1.33%).

CONCLUSIONS

In the present study we have clearly demonstrated the immediate expression of the pro-inflammatory cytokines TNF-alpha, IL-1alpha, and IL-6 in the bronchiolar epithelium in the first hours after lung irradiation. A second, long-lasting release of these cytokines by the bronchiolar and alveolar epithelium, as well as by inflammatory cells, was observed at the onset of acute pneumonitis. Therefore, we postulate that lung irradiation causes immediate epithelial reaction, with the bronchiolar epithelium becoming a significant source of pro-inflammatory cytokines capable of promoting inflammation through recruitment and activation of inflammatory cells.

[Long-term response of bronchopulmonary system in liquidators of Chernobyl accident]

Liquidators of chernobyl accident consequences were subjected to simultaneous external gamma-beta-radiation and inhalation of particles containing radionuclide aerosols and nonradiation toxic chemicals. findings are typical defects of the liquidators examination: assignment of individuals with pulmonary disorders to post-accident work, misinterpretation of the disease severity with underestimation of previous occupational anamnesis and aggravating role of nonradiation.

Bronchial stenosis: An underreported complication of high-dose external beam radiotherapy for lung cancer?

PURPOSE

To assess the incidence of clinically significant bronchial stenosis in patients treated with high doses (i.e., >70 Gy) of twice-daily external beam radiation therapy (RT).

METHODS AND MATERIALS

The outcomes of 103 patients with unresectable non-small-cell lung cancer, treated twice daily to doses ranging from 7080 to 8640 cGy between 1992 and 2001, were analyzed. Most were treated on prospective clinical trials. For the dose-effect comparison, the patients were divided on the basis of the total dose: 67 received 74 Gy (range, 70.8-74.5 Gy; median, 73.6 Gy), 20 received 80 Gy, and 16 received 86 Gy (range, 85.2-86.4 Gy; median, 86.4 Gy). Sixty-six patients received sequential chemotherapy before RT. RT-induced bronchial stenosis was defined as symptomatic airway narrowing diagnosed by bronchoscopy or computed tomography scan without evidence of recurrent tumor in that region.

RESULTS

Eight patients developed RT-induced, clinically significant, bronchial stenosis 2-48 months (median, 6 months) after RT. The 1-year and 4-year actuarial rate of stenosis was 7% and 38%, respectively. The median overall survival was 2.5 years (5 of 8 were alive at the writing of this report). A suggestion was also found of a dose-response effect with external beam radiotherapy-induced stenosis, with a rate of 4% and 25% at a dose of approximately 74 Gy and 86 Gy, respectively.

CONCLUSION

Radiation therapy-induced bronchial stenosis is a significant clinical complication of dose escalation for lung cancer. This complication has been previously mentioned in the literature, but ours is the largest report to date, and the findings suggest that the risk rises with increasing dose. It is likely that this process would manifest in more patients if their disease were controlled well enough for more prolonged survival.

Microdosimetry of radon progeny alpha particles in bronchial airway bifurcations

A Monte Carlo code, initially developed for the calculation of microdosimetric spectra for alpha particles in cylindrical airways, has been extended to allow the computation of microdosimetric parameters for multiple source-target configurations in bronchial airway bifurcations. The objective of the present study was to investigate the effects of uniform and non-uniform radon progeny surface activity distributions in symmetric and asymmetric bronchial airway bifurcations on absorbed dose, hit frequency, lineal energy, single hit specific energy and LET spectra. In order to assess the effects of multiple hits, dose-dependent specific energy spectra were calculated by solving the compound Poisson process by iterative convolution. While the simulations showed significant differences of cellular dose quantities at different cell locations for uniformly distributed surface activities, even higher variations, as high as several orders of magnitude, were observed for non-uniform surface activity distributions, depending on the location of the cell and the local activity distribution.

Spindle checkpoint and apoptotic response in alpha-particle transformed human bronchial epithelial cells

The mitotic spindle checkpoint and apoptosis in response to nocodazole, a microtubule-disrupting agent, were investigated in the alpha-particle transformed human bronchial epithelial cell lines BERP35T1, BERP35T4 and the parental BEP2D cell line. When treated with 0.2 microg/ml of nocodazole, BEP2D and BERP35T1 cells were efficiently arrested in the mitotic phase, whilst BERP35T4, a transformed cell line showing chromosomal instability, failed to be arrested as evidenced by a low G2/M fraction. BERP35T4 cells also showed a higher proportion of aneuploids when treated with nocodazole or not. Thus, the BERP35T4 cell line has a defect in spindle checkpoint function. The extent of apoptosis induced by nocodazole (0.3 microg/ml) was significantly higher (2-fold to 2.5-fold) in BEP2D cells than in the two transformed cell lines. Furthermore, the induced apoptosis was found to occur predominantly before mitotic division in BEP2D cells. In BERP35T4 cells, however, 50% of induced apoptosis occurred before mitotic division and 50% occurred after division in binucleated cells when co-treated with cytochalasin B. The 5'-CpG island of the Chfr gene, a mitotic checkpoint gene that functions in entry into metaphase, was found to be methylated in BERP35T4 cells but not in BEP2D cells. Consistent with methylation, the expression of the Chfr gene was markedly suppressed in BERP35T4 cells. Our results suggest that the impaired spindle checkpoint and abnormal apoptotic response may be related to the oncogenic progression of human bronchial epithelial cells initiated by exposure to alpha-particles.