Determining the Chernobyl impact on sediments of a pre-Alpine lake with a very comprehensive set of data

Man-made and natural radionuclides in Lake Wallersee were determined in the pre-Alpine environment at the northern slope of the Alps, which was heavily affected by the Chernobyl fallout in May 1986. The objective of this study was to get knowledge of location and quantity of man-made radionuclide input (especially (137)Cs) generated in the Chernobyl accident to lake sediments. Eleven sediment cores were sampled and activity depth profiles of (137)Cs and (210)Pb were determined with 5mm depth-resolution. The Chernobyl fallout produced an extreme (137)Cs peak in the sediment cores providing an excellent time marker. The chronological interpretation of deeper sediment layers was done by radiochemical analysis of (90)Sr and (239+240)Pu, which were released during atmospheric weapons' tests in the 1950s and 1960s. This allowed a complete chronological analysis of the sediment cores with a very compact set of data.

Dosimetric models used in the Alpha-Risk project to quantify exposure of uranium miners to radon gas and its progeny

The European project Alpha-Risk aims to quantify the cancer and non-cancer risks associated with multiple chronic radiation exposures by epidemiological studies, organ dose calculation and risk assessment. In the framework of this project, mathematical models have been applied to the organ dosimetry of uranium miners who are internally exposed to radon and its progeny as well as to long-lived radionuclides present in the uranium ore. This paper describes the methodology and the dosimetric models used to calculate the absorbed doses to specific organs arising from exposure to radon and its progeny in the uranium mines. The results of dose calculations are also presented.

Airway geometry models of children's lungs for use in dosimetry modeling

Single-path whole-lung and lobar models of the lungs of 11 children between 3 mo and 21 yr of age were developed based on a combination of cast data and published information on distal airway dimensions. The cast data used to generate these models were taken from one of the largest databases of actual measurements in children. The methods used to develop the children's models were based on techniques that have been used to develop adult single-path airway geometry models. Model dimensions for the conducting airways, as well as the estimated dead space, for all children fell within the range of the limited published information. Thus, the method for estimating airway dimensions in adults may be successfully applied to develop estimates of airway dimensions in children. The predicted total lung capacity (TLC) for the older children (aged 8 to 21 yr) fell within or near the range arising from published scaling equations. The assumptions used to generate the gas exchange region for children 8 yr and older produced results that were reasonably consistent with available physiological data. However, these assumptions do not result in a physiologically consistent gas exchange region for children 3 yr of age and younger; also, to maintain physiologically reasonable relationships between dead space and alveolar volume, the models for children 3 yr of age and younger resulted in predicted TLCs well below those predicted using published scaling equations. These discrepancies may be reflective of dysanaptic growth, in which the alveolar region is growing more rapidly than the airways. The results for children 3 yr of age and under suggest the need for a greater understanding of lung development during this critical period. This is particularly important considering the increasing evidence that exposure to pollutants and other toxicants and allergens during the first 2 yr of life may have long-term consequences on respiratory disease outcomes. Our results suggest that the geometry model airway dimensions for all ages are appropriate for use with dosimetry models, but dosimetry modelers need to assess carefully the reasonableness of TLC and functional residual capacity volumes to which airway dimensions are scaled for children 3 yr of age and under.

Detrimental and protective bystander effects: a model approach

This work integrates two important cellular responses to low doses, detrimental bystander effects and apoptosis-mediated protective bystander effects, into a multistage model for chromosome aberrations and in vitro neoplastic transformation: the State-Vector Model. The new models were tested on representative data sets that show supralinear or U-shaped dose responses. The original model without the new low-dose features was also tested for consistency with LNT-shaped dose responses. Reductions of in vitro neoplastic transformation frequencies below the spontaneous level have been reported after exposure of cells to low doses of low-LET radiation. In the current study, this protective effect is explained with bystander-induced apoptosis. An important data set that shows a low-dose detrimental bystander effect for chromosome aberrations was successfully fitted by additional terms within the cell initiation stage. It was found that this approach is equivalent to bystander-induced clonal expansion of initiated cells. This study is an important step toward a comprehensive model that contains all essential biological mechanisms that can influence dose-response curves at low doses.

Combined medical-psychiatric inpatient units

Considering the large number of elderly patients in acute hospitals who receive medical as well as psychiatric treatment because of relevant comorbidity, adequate interdisciplinary treatment models have to be developed and applied. The Centre for Elderly, a cooperation project between the departments of geriatric and psychogeriatric medicine in a community hospital in Germany, was founded in 2000. In addition to traditionally structured units, the centre consists of interdisciplinary units. Patient-, staff- and hospital-related characteristics influenced by the reformation of both departments were evaluated by comparing hospital-based registry data records containing age, gender, main and minor diagnoses, length of stay and patient transferrals within the centre. Experts working at the centre were asked to take a stand on the development of the treatment quality, allocation of patients, diagnostic procedures, consultation services and information transmission. The number of admissions to the Centre for the Elderly increased within one year. The distribution of the main diagnose groups remained unchanged, with an overlap between the geriatric and psychogeriatric department consisting of the main diagnoses dementia and depression. The length of stay and the number of transferrals decreased significantly in both departments. The majority of the interviewed employees stated that the treatment quality and the allocation of patients were improved. We conclude that interdisciplinary treatment between the departments of psychiatry and geriatric medicine may contribute to the medical needs of subgroups of elderly inpatients suffering from medical-psychiatric comorbidity.

Increased risk of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers after breast-conserving therapy compared to mastectomy

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Background: BRCA mutation carriers affected by breast cancer face an elevated risk of contralateral breast cancer (clBrCa). We here aimed at estimating the influence of breast conserving therapy (BCT) versus mastectomy (MXT) on the rik of clBrCa. Methods: We conducted a retrospective cohort study in 3810 index patients (pts) collected within the CHBOC. Deleterious BRCA1 or BRCA2 mutations were detected in 921 pts and medical records were obtained from 532 pts (344 BRCA1, 184 BRCA2 mutation carriers, 4 both) of whom 261 (49%) underwent BCT and 271 (51%) MXT. Pts were followed from the initial diagnosis of breast cancer until clBrCa or censored at time of prophylactic contralateral mastectomy, oophorectomy, death, or date of last visit. Median age at first diagnosis was 39.9 years (range 17.5 to 79.0) and median follow up 48.84 months (3413 person years). The hazard ratio (HR) was estimated using multivariate Cox regression analysis adjusting for conduct of radiotherapy, age at first breast cancer, and affected BRCA gene. Results: In the univariate analysis the risk of clBrCa was 12.2% (95% CI 7.6 to 16.8) at 5 years and 24.9% (95% CI 18.0 to 31.9) at 10 years for pts treated with MXT and 25.9% (95% CI 18.8 to 33.1) at 5 years and 45.7% (95% CI 35.0 to 56.5) at 10 years for pts treated with BCT. In the multivariate analysis, the HR was 1.8 for BCT versus MXT (95% CI 1.2 to 2.7). Neither age at diagnosis of the first primary nor BRCA mutation status were significantly predictive. A subgroup analysis comparing BCT plus radiotherapy with MXT minus radiotherapy revealed a HR of 1.6 (95% CI 1.02 to 2.56) for the BCT group. Conclusions: We report for the first time a 1.8-fold increased risk of clBrCa in BRCA mutation carriers undergoing BCT versus MXT. Scattered radiation is the most probable causation. Although results from further studies such as the WECARE study should be awaited, our results provide evidence that recommendations for primary brCa treatment of BRCA mutation carriers must to be reconsidered.

No significant financial relationships to disclose.

Fast Variability of Tera–Electron Volt γ Rays from the Radio Galaxy M87

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.

HESS observations of the galactic center region and their possible dark matter interpretation

The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin.

Stochastic modeling predictions for the clearance of insoluble particles from the tracheobronchial tree of the human lung

Bronchial clearance of deposited particles was simulated using a stochastic model of the tracheobronchial tree. The clearance model introduced in this study considers (1) a continuous decrease of the mucus thickness from the trachea to the terminal bronchioles according to a linear or an exponential function, (2) the possibility of mucus discontinuities, which are mainly found in intermediate and distal airways of the tracheobronchial compartment, (3) mucus production in proximal airways, (4) a slow bronchial clearance phase due to the capture of a defined particle fraction f (s) in the periciliary sol phase, and (5) an eventual delay of the mucociliary transport at carinal ridges of airway bifurcations. Based on the concept of mucus volume conservation in single bifurcations, a reduction of the thickness of the mucus blanket from proximal to distal airways causes a significant increase of the mucus velocities in small ciliated airways compared to other stochastic modeling predictions assuming a constant thickness of the mucus layer throughout the conducting airways. This effect is further enhanced by the consideration of mucus discontinuities. In contrast, the ability of bronchial airways to produce a certain volume of mucus has a decreasing effect on the mucus velocities. In all generated clearance velocity models, mucociliary clearance is completely terminated within 24 h after exposure, consistent with the experimental evidence. Implementation of a slow bronchial clearance phase predicts a long-term retention fraction, which is fully cleared from the lung after several weeks. For 1-microm MMAD particles, 24-h retention varies between 0.42 and 0.52, in line with the suggestions of the ICRP. Mucus delay at carinal ridges only affects short-term clearance by increasing the retained particle fraction at a given time, while long-term retention is not influenced.

An international multi-center study to assess the clinical accuracy of the molecular subclassification of leukemia by gene expression profiling

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Background: Microarray analysis can identify differentially expressed genes of pediatric and adult leukemias. Recently, the MILE (Microarray Innovations in Leukemia) study has started in 11 centers (European Leukemia Network: 7, USA: 3, Singapore: 1). MILE compares the accuracy of gene expression profiles of 16 acute and chronic leukemia subclasses, MDS, and non-leukemia as control group to routine diagnostic workup. Methods: In a pre-phase each center was trained on the identical microarray protocol (HG-U133 Plus 2.0 microarrays). 2 cell lines (MCF-7, HEPG2) and cell lysates of three leukemia patients (AML t(8;21), CML, CLL) were tested. After proficiency testing, centers started to analyze 2000 leukemia samples. Results: The pre-phase demonstrated a very high intra- and inter-laboratory comparability among centers. Using principal component analysis each sample type was clustered with no observable sub-grouping of the different centers. Replicates of leukemia samples demonstrated squared correlation coefficients between 0.930–0.997 for CML, 0.936–0.998 for CLL, and 0.940–0.999 for AML t(8;21).Here we present classification results of the first series of 607 pts. that were included prospectively in a training data set (total n=1,049) to form linear classifiers for all 153 class pairs. The average cross-validation accuracy is 89.4%. In first independent cohort (HG-U133 Plus 2.0, n=105) 89.5% classification accuracy were achieved. In a second independent cohort (n=1,094), analyzed previously in two centers on HG-U133A/B microarrays, 83.5% classification accuracy were achieved. In detail, 136 out of 139 (97.8%) chronic leukemia samples (CML or CLL) were classified fully in agreement with standard diagnostic procedures. For acute leukemia subtypes 767 out of 904 (84.8%) were classified correctly. Interestingly, an AML-like signature can be found in MDS samples with IPSS >1.5. Conclusions: This international multi-center study demonstrates a very high inter- and intralaboratory reproducibility of microarray analyses. Data will be used to design a new custom format microarray dedicated to further develop the application of gene expression profiling for diagnosis and subclassification of leukemia.

No significant financial relationships to disclose.

Clinical and immune responses of WT1-peptide vaccination in patients with acute myeloid leukemia

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Background: The transcription factor Wilms tumor protein (WT) 1 belongs to a new generation of tumor antigens, as it is essential for tumor cell proliferation. WT1 is highly expressed both in myeloid leukemias and many carcinomas. This phase 2 proof-of-concept trial was initiated to determine immunogenicity and toxicity of vaccination with a novel HLA-A2-restricted WT1 peptide vaccine. Methods: Sixteen HLA-A2-positive patients with acute myeloid leukemia and one patient with myelodysplasia received 3–18 vaccinations (median 8) of WT1. 126–134 peptide (0.2 mg) together with the T helper protein keyhole limpet hemocyanin (1 mg) and in addition GM-CSF (75 mcg for four days) and. Twelve patients had elevated blast counts at study entry and 5 patients complete remission with high risk for relapse. Results: Six of 12 patients with presence of leukemic blasts had evidence of antileukemic activity. One patient achieved complete remission for 12 months. The patient with myelodysplasia RAEB II had a major response of neutrophils and platelets. Two patients had minor responses with transient clearance of peripheral blasts or improvement of hematopoiesis, and two patients achieved disease stabilization for 3 and 14 months. WT1 transcripts as molecular disease marker decreased in 5 of these 6 patients and also in 4 of 5 high-risk patients. No significant toxicity occurred. The generation of a WT1-specific T cell response in peripheral blood and bone marrow was detected in 9 of 13 patients by tetramer analysis and 8 of 13 patients by intracellular cytokine staining. Conclusion: These results show that WT1 vaccination can induce functional T cell responses associated with antileukemic activity and warrant trials of WT1 vaccination in patients at high risk of relapse and with WT1-expressing carcinomas.

No significant financial relationships to disclose.

A low level of extragalactic background light as revealed by γ-rays from blazars

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.

Discovery of very-high-energy γ-rays from the Galactic Centre ridge

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

A model for the induction of chromosome aberrations through direct and bystander mechanisms

A state vector model (SVM) for chromosome aberrations and neoplastic transformation has been adapted to describe detrimental bystander effects. The model describes initiation (formation of translocations) and promotion (clonal expansion and loss of contact inhibition of initiated cells). Additional terms either in the initiation model or in the rate of clonal expansion of initiated cells, describe detrimental bystander effects for chromosome aberrations as reported in the scientific literature. In the present study, the SVM with bystander effects is tested on a suitable dataset. In addition to the simulation of non-linear effects, a classical dataset for neoplastic transformation in C3H 10T1/2 cells after alpha particle irradiation is used to show that the model without bystander features can also describe LNT-like dose responses. A published model for bystander induced neoplastic transformation was adapted for chromosome aberration induction and used to compare the results obtained with the different models.

Modeling lung cancer incidence in rats following exposure to radon progeny

Lung cancer incidence in Sprague-Dawley rats was simulated by a biologically based carcinogenesis model, which is formulated mathematically in terms of a stochastic state-vector model. Doses to the sensitive target cells in the bronchial epithelium of the rat lung were calculated by a stochastic dosimetry model, considering the distinct monopodial branching structure and the crossfire of alpha particles from alveolar tissue to bronchial epithelium. Bronchial and alveolar cellular doses could reasonably be approximated by lognormal distributions, with geometric standard deviations (GSD) between 7 and 10, depending on exposure conditions. Based on a dose-exposure conversion factor of 8.5 mGy WLM(-1) and a GSD of 8, lung cancer incidences were calculated for each cumulative exposure category in the rat inhalation study, consisting of different exposure rates and exposure times. The fair agreement between theoretical predictions and experimental data over the whole exposure range emphasises the necessity to incorporate the full cellular dose distributions rather than their mean values.

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.

Incorporation of microdosimetric concepts into a biologically-based model of radiation carcinogenesis

The generalised state-vector model of radiation carcinogenesis (SVM) simulates radiation induced biological effects by expressing the transition rates between the various initiation and promotion stages in terms of dose rate for low and high linear energy transfer (LET) particles. In the present work, the SVM has been reformulated to incorporate single track characteristics of particles with varying LET. Transition rates of the initiation phase were expressed as functions of LET by describing the complexity and clustering of DNA double strand breaks (DSBs) and its effect on repair kinetics, while the promotion phase was reformulated based on a multi-target single-hit hypothesis. Such an approach allows the consideration of hit frequencies and the variability of the specific energy and LET spectra of radon progeny alpha particles in bronchial target cells for different exposure conditions.

A multi-compartment model for slow bronchial clearance of insoluble particles--extension of the ICRP human respiratory tract models

To incorporate the various mechanisms that are presently assumed to be responsible for the experimentally observed slow bronchial clearance into the HRTM, a multi-compartment model was developed to simulate the clearance of insoluble particles in the tracheobronchial tree of the human lung. The new model considers specific mass transfer paths that may play an important role for slow bronchial clearance. These include the accumulation of particulate mass in the periciliary sol layer, phagocytosis of stored particles by airway macrophages and uptake of deposited mass by epithelial cells. Besides the gel layer representing fast mucociliary clearance, all cellular and non-cellular units involved in the slow clearance process are described by respective compartments that are connected by specific transfer rates. The gastrointestinal tract and lymph nodes are included into the model as final accumulation compartments, to which mass is transferred via the airway route and the transepithelial path. Predicted retention curves correspond well with previously published data.