Eurados review of retrospective dosimetry techniques for internal exposures to ionising radiation and their applications.

This work presents an overview of the applications of retrospective dosimetry techniques in case of incorporation of radionuclides. The fact that internal exposures are characterized by a spatially inhomogeneous irradiation of the body, which is potentially prolonged over large periods and variable over time, is particularly problematic for biological and electron paramagnetic resonance (EPR) dosimetry methods when compared with external exposures. The paper gives initially specific information about internal dosimetry methods, the most common cytogenetic techniques used in biological dosimetry and EPR dosimetry applied to tooth enamel. Based on real-case scenarios, dose estimates obtained from bioassay data as well as with biological and/or EPR dosimetry are compared and critically discussed. In most of the scenarios presented, concomitant external exposures were responsible for the greater portion of the received dose. As no assay is available which can discriminate between radiation of different types and different LETs on the basis of the type of damage induced, it is not possible to infer from these studies specific conclusions valid for incorporated radionuclides alone. The biological dosimetry assays and EPR techniques proved to be most applicable in cases when the radionuclides are almost homogeneously distributed in the body. No compelling evidence was obtained in other cases of extremely inhomogeneous distribution. Retrospective dosimetry needs to be optimized and further developed in order to be able to deal with real exposure cases, where a mixture of both external and internal exposures will be encountered most of the times.

Heteroresistant Bacteria Detected by an Extended Raman-Based Antibiotic Susceptibility Test.

Worldwide, multiresistant bacterial strains are emerging at unprecedented rates. This development seriously threatens the ability of humanity to treat even common infections, resulting in disability and death. Furthermore, this development endangers all medical achievements including cancer therapy or organ transplantations. Therefore, the World Health Organization has endorsed antimicrobial resistance as a great threat to humanity. To still allow effective treatment of patients, rapid, automated, and reliable antibiotic susceptibility testing (AST) of bacterial pathogens is essential. Thereby, speed and sensitivity of the AST results are crucial for improving patient care. Here, Raman spectroscopy as a nondestructive technique providing chemical-specific information is employed to monitor the deuterium uptake of metabolically active bacteria during antibiotic treatment, enabling fast and reliable AST. For this purpose, a bulk sample-preparation method was developed, allowing a high-throughput analysis of a significant number of cells. A protocol was developed for Gram-positive (Enterococcus faecalis) and Gram-negative (Escherichia coli) reference strains and was tested on 51 clinical isolates with well-characterized resistance phenotypes against ampicillin, ciprofloxacin, meropenem, and vancomycin. Borderline resistant and heteroresistant phenotypes were observed and further investigated. This is of critical importance as the sensitive detection of low-frequency heteroresistance in bacterial populations is a huge challenge. Such isolates seem susceptible but are resistant to treatment in vivo. Automatable analysis detects strong phenotypes within 3 h. On the basis of experimental and modeled data, heteroresistance is estimated to be detectable down to frequencies of 10-6 and investigated on clinical isolates as a proof-of-concept study, but requiring longer incubation time.

Identifying Dormant Growth State of Mycobacteria by Orthogonal Analytical Approaches on a Single Cell and Ensemble Basis.

Tuberculosis is currently the single most deadly infectious disease in the world and a public health priority as defined by WHO. Although the disease is in general curable, treatment success is hampered by the necessity of a long and side effect prone treatment. Low treatment efficiency may be partly due to the special growth states that mycobacteria enter to avoid being killed by antibiotics and to persist longer within the host. Such growth states have been recently defined as dormant or persistent. We produced dormant model-organism cultures using an acidification model and characterized those by a multilayered approach using mass spectrometry (MALDI-TOF), microscopy (SEM, Raman), and microbiological techniques (CFU, OD600, ATP-levels). With a fast and 96-well-adapted extraction protocol, mycobacteria could be inactivated and extracted for MALDI-TOF analysis. For the first time, we demonstrate growth-state-dependent changes in the mass signatures of the culture, allowing for a reliable differentiation of dormant state and exponential growth. We also demonstrate resuscitation from dormant state back to exponential growth. Viable mycobacteria were immobilized, and single organisms were analyzed individually by Raman microscopy. For single-cell Raman microscopy, Mycobacterium smegmatis cultures were fixed using a new fast and gentle single-step immobilization technique on a hydrophobic glass slide. We were able to distinguish single viable bacteria in the dormant state from their rapidly growing, genetically identical counterparts, identifying the growth state of the culture based on single-organism spectra. This allows for the separation of heterogeneous cultures depending on their growth state using the destruction-free optical method of Raman microscopy.

A COMPARISON OF DIFFERENT SPECTRA DECONVOLUTION METHODS USED IN EPR DOSIMETRY WITH GORILLA® GLASSES.

Two different spectra deconvolution methods have been compared on samples of Gorilla® Glass (GG) irradiated in the dose range 0-20 Gy and measured with X-band EPR. The first method used a matrix deconvolution procedure using sample-specific sets of reference signals. The second method used a 'universal' set of eight reference signals (due to five electron centers, two hole centers and a background) to fit EPR spectra from any GG sample. Dose-responses curves were constructed for each individual reference signal. These were then used to test reconstruction of a laboratory-administered dose of 2 Gy. For the matrix method, the values of the reconstructed and nominal doses were within ± 20% after averaging measurements from three aliquots of each sample. For the universal method, the most promising results were obtained with E1, E4 and H1 signals. The fitting failed for one sample, due to dominance of the background signal.

APPLICATION OF EPR TOOTH DOSIMETRY FOR VALIDATION OF THE CALCULATED EXTERNAL DOSES: EXPERIENCE IN DOSIMETRY FOR THE TECHA RIVER COHORT.

This study applies EPR tooth dosimetry for validation of external doses calculated with the TRDS-2016. EPR-based external dose in tooth enamel is calculated by subtraction of the contributions of natural and anthropogenic sources from the exposure of interest. These subtracted terms may contribute substantially to the overall uncertainty of the EPR-derived external dose. The validation method strongly depends on the uncertainties. The current study combines the results of a number of previous papers to propagate the uncertainty of EPR-derived external doses. It is concluded that the overall uncertainties of D ≥ 500 mGy are comparable with measurement uncertainties (≤30%); the overall uncertainties of D < 500 mGy become higher as the EPR-dose decreases because they are strongly effected by all other factors of influence. More than 70% of investigated individuals were exposed externally to doses <100 mGy with uncertainties >100%. Therefore, the validation task can be solved only based on statistical approaches. The validation of the TRDS-2016 predictions demonstrates good convergence of group-averages with EPR-based doses. The method for validation of the uncertainty of TRDS-2016 predictions should be also designed based on statistical approaches.

Camel molar tooth enamel response to gamma rays using EPR spectroscopy.

Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH pp) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry.

[New microbiological techniques]. / Neue mikrobiologische Techniken.

Microbiological diagnostic procedures have changed rapidly in recent years. This is especially true in the field of molecular diagnostics. Classical culture-based techniques are still the gold standard in many areas; however, they are already complemented by automated and also molecular techniques to guarantee faster and better quality results. The most commonly used techniques include real-time polymerase chain reaction (RT-PCR) based systems and nucleic acid hybridization. These procedures are used most powerfully from direct patient samples or in assays to detect the presence of nonculturable or fastidious organisms. Further techniques such as DNA sequencing are not yet used routinely for urological samples and can be considered experimental. However, in conjunction with dropping prices and further technical developments, these techniques promise to be used much more in the near future. Regarding bacterial identification from culture, mass spectrometry (MALDI-TOF MS) has become the technique of choice in recent years especially in Europe. It has tremendously shortened the time to result. This is now going to be extended to antibiotic susceptibility testing. This is of paramount importance in view of ever rising antimicrobial resistance rates. Techniques described in this review offer a faster and better microbiological diagnosis. Such continuous improvements are critical especially in times of cost pressure and rising antimicrobial resistance rates. It is in our interest to provide the best possible care for patients and in this regard a good and effective communication between the laboratory and the clinician is of vital importance.

External dose reconstruction in tooth enamel of Techa riverside residents.

This study summarizes the 20-year efforts for dose reconstruction in tooth enamel of the Techa riverside residents exposed to ionizing radiation as a result of radionuclide releases into the river in 1949-1956. It represents the first combined analysis of all the data available on EPR dosimetry with teeth of permanent residents of the Techa riverside territory. Results of electron paramagnetic resonance (EPR) measurements of 302 teeth donated by 173 individuals living permanently in Techa riverside settlements over the period of 1950-1952 were analyzed. These people were residents of villages located at the free-flowing river stream or at the banks of stagnant reservoirs such as ponds or blind river forks. Cumulative absorbed doses measured using EPR are from several sources of exposure, viz., background radiation, internal exposure due to bone-seeking radionuclides (89Sr, 90Sr/90Y), internal exposure due to 137Cs/137mBa incorporated in soft tissues, and anthropogenic external exposure. The purpose of the present study was to evaluate the contribution of different sources of enamel exposure and to deduce external doses to be used for validation of the Techa River Dosimetry System (TRDS). Since various EPR methods were used, harmonization of these methods was critical. Overall, the mean cumulative background dose was found to be 63 ± 47 mGy; cumulative internal doses due to 89Sr and 90Sr/90Y were within the range of 10-110 mGy; cumulative internal doses due to 137Cs/137mBa depend on the distance from the site of releases and varied from 1 mGy up to 90 mGy; mean external doses were maximum for settlements located at the banks of stagnant reservoirs (~500 mGy); in contrast, external doses for settlements located along the free-flowing river stream did not exceed 160 mGy and decreased downstream with increasing distance from the site of release. External enamel doses calculated using the TRDS code and derived from the EPR measurements were found to be in good agreement.

[Louse-borne-relapsing-fever in refugees from the Horn of Africa; a case series of 25 patients]. / 25 Fälle von Läuserückfallfieber bei Flüchtlingen aus Ostafrika.

Background | Relapsing fever is divided into tick borne relapsing fever (TBRF) and louse borne relapsing fever (LBRF). This report describes 25 refugees from East Africa who were diagnosed to suffer from LBRF within a period of 6 month only at a single hospital in Munich / Germany. Material & Methods | The aim was to point out common clinical features as well as laboratory findings and clinical symptoms before and after initiation of treatment in 25 patients with louse borne relapsing fever (LBRF) who were diagnosed and treated at Klinikum München Schwabing from August 2015 to January 2016. To the best of our knowledge this is the largest case series of LBRF in the western world for decades. Main focus of the investigation was put on clinical aspects. Results | All 25 patients suffered from acute onset of high fever with chills, headache and severe prostration. Laboratory analysis showed high CRP and a marked thrombocytopenia. A Giemsa blood stain was procured immediately in order to look for malaria. In the blood smear spirochetes with typical shape and aspect of borrelia species could be detected.The further PCR analysis confirmed infection with Borrelia recurrentis. Treatment with Doxycycline was started forthwith. The condition improved already on the second day after treatment was started and all were restored to health in less than a week. Apart from a mild to moderate Jarisch-Herxheimer-reaction we didn`t see any side effects of the therapy. Conclusion | LBRF has to be taken into account in feverish patients who come as refugees from East-Africa. It seems that our patients belong to a cluster which probably has its origin in Libya and more patients are to be expected in the near future. As LBRF might cause outbreaks in refugee camps it is pivotal to be aware of this emerging infectious disease in refugees from East-Africa.

Analysis of EPR and FISH studies of radiation doses in persons who lived in the upper reaches of the Techa River.

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth, and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teeth and bones that act as a source of confounding local exposures. In order to estimate and subtract doses from incorporated (89,90)Sr, the EPR and FISH assays were supported by measurements of (90)Sr-body burdens and estimates of (90)Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR to FISH measurements for residents of the upper Techa River were found to be consistent: The mean values vary from 510 to 550 mGy for the villages located close to the site of radioactive release to 130-160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2-2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the most recent Techa River Dosimetry System (TRDS). The TRDS external dose assessments are based on the data on contamination of the Techa River floodplain, simulation of air kerma above the contaminated soil, age-dependent lifestyles and individual residence histories. For correct comparison, TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from (137)Cs incorporated in donors' soft tissues. It is shown here that the TRDS-based absorbed doses in tooth enamel and muscle are in agreement with EPR- and FISH-based estimates within uncertainty bounds. Basically, this agreement between the estimates has confirmed the validity of external doses calculated with the TRDS.

Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk.

In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960.

Rapid detection of antibiotic resistance based on mass spectrometry and stable isotopes.

With the emergence and growing complexity of bacterial drug resistance, rapid and reliable susceptibility testing has become a topical issue. Therefore, new technologies that assist in predicting the effectiveness of empiric antibiotic therapy are of great interest. Although the use of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the rapid detection of antibiotic resistance is an attractive option, the current methods for MALDI-TOF MS susceptibility testing are restricted to very limited conditions. Here, we describe a technique that may allow for rapid susceptibility testing to an extent that is comparable to phenotypic methods. The test was based on a stable isotope labelling by amino acids in cell culture (SILAC)-like approach. This technique was used to visualise the growth of bacteria in the presence of an antibiotic. Pseudomonas aeruginosa was chosen as the model organism, and strains were incubated in normal medium, medium supplemented with (13)C6-(15) N2-labelled lysine and medium supplemented with labelled lysine and antibiotic. Peak shifts occurring due to the incorporation of the labelled amino acids were detected by MALDI-TOF MS. Three antibiotics with different mechanisms of action, meropenem, tobramycin and ciprofloxacin, were tested. A semi-automated algorithm was created to enable rapid and unbiased data evaluation. With the proposed test, a clear distinction between resistant and susceptible isolates was possible for all three antibiotics. The application of SILAC technology for the detection of antibiotic resistance may contribute to accelerated and reliable susceptibility testing.

TcpC protein from E. coli Nissle improves epithelial barrier function involving PKCζ and ERK1/2 signaling in HT-29/B6 cells.

The probiotic Escherichia coli Nissle 1917 (EcN) is widely used to maintain remission in ulcerative colitis. This is thought to be mediated by various immunomodulatory and barrier-stabilizing effects in the intestine. In this study, the mechanisms of barrier modulation by EcN were studied in the human epithelial HT-29/B6 cell culture model.EcN supernatant increased transepithelial resistance (TER) and reduced permeability to mannitol because of sealing of the paracellular passage pathway as revealed by two-path impedance spectroscopy. This increase in TER was attributed to the TcpC protein of EcN. TcpC induced protein kinase C-ζ (PKCζ) and extracellular-signal-regulated kinase 1/2 (ERK1/2) phosphorylation, which in turn resulted in upregulation of the barrier-forming tight junction protein claudin-14. By specific silencing of protein expression by small interfering RNA (siRNA), the sealing function of claudin-14 was confirmed. In conclusion, the TcpC protein of EcN affects innate immunity by improving intestinal barrier function through upregulation of claudin-14 via PKCζ and ERK1/2 signaling.

Feasibility of a multdisciplinary lung cancer videoconference between a peripheral hospital and a comprehensive cancer centre.

OBJECTIVE: Treatment of lung cancer patients is changing rapidly and new treatment options have emerged in recent years. In 2007, to guarantee the best treatment procedure for lung cancer patients being treated in our peripheral hospital, we decided to introduce an interdisciplinary tumour videoconference between the Haemato-Oncological Day Hospital in Merano and the Comprehensive Cancer Centre Innsbruck. This retrospective analysis aims to describe the feasibility of such a conference. PATIENTS AND METHODS: Two hundred and three patients with lung cancer treated at the peripheral hospital of Merano between May 2003 until May 2011 were retrospectively analysed. After introduction of the tumour videoconference in 2007, 54% (n = 110) of the patients in this cohort were discussed in the conference. RESULTS: One hundred and four videoconferences were performed. Videoconference was feasible for 110 patients. Radiotherapeutic treatments were prescribed more frequently in patients from the conference group. Overall, major and minor treatment changes were undertaken in 7% (n = 8) and 18% (n = 20), respectively. CONCLUSION: Interdisciplinary tumour videoconference is feasible between a peripheral hospital and a comprehensive cancer centre. Radiotherapeutic treatment was prescribed more frequently, suggesting that such a conference facilitates the access to cancer-centre-specific treatment modalities. Accordingly, tumour videoconference between a peripheral hospital and a cancer centre is to be recommend.

Review of reconstruction of radiation incident air kerma by measurement of absorbed dose in tooth enamel with EPR.

Electron paramagnetic resonance dosimetry with tooth enamel has been proved to be a reliable method to determine retrospectively exposures from photon fields with minimal detectable doses of 100 mGy or lower, which is lower than achievable with cytogenetic dose reconstruction methods. For risk assessment or validating dosimetry systems for specific radiation incidents, the relevant dose from the incident has to be calculated from the total absorbed dose in enamel by subtracting additional dose contributions from the radionuclide content in teeth, natural external background radiation and medical exposures. For calculating organ doses or evaluating dosimetry systems the absorbed dose in enamel from a radiation incident has to be converted to air kerma using dose conversion factors depending on the photon energy spectrum and geometry of the exposure scenario. This paper outlines the approach to assess individual dose contributions to absorbed dose in enamel and calculate individual air kerma of a radiation incident from the absorbed dose in tooth enamel.

A novel ex vivo set-up for dynamic long-term characterization of processes on mucosal interfaces by confocal imaging and simultaneous cytokine measurements.

We present a novel organ-explant imaging system for easy and cost-effective extended-time observation of host-pathogen interactions at mucosal interfaces. Data are complemented by parallel cytokine measurements at high temporal resolution. The set-up is based on a custom-built reusable organ chamber compatible with standard microscopes. Luminal and basal side of the explanted mucosa are connected to separate channels for optimized incubation and cytokine measurements, oxygen is provided via membrane oxygenation. Dynamic imaging with confocal microscopy permits a detailed analysis of the dynamics of pathogen-host cell interactions at the mucosal interface and the neighbouring tissue at high resolution. The system can be applied to various hollow organs with few modifications. Here we present first applications to study representative infections such as uropathogenic Escherichia coli (UPEC) infections in the urinary bladder or amoebiasis of the colon by using mouse organs. We show (i) intracellular bacteria in UPEC infections, (ii) phagocytic events on tissue during infection, as well as (iii) tissue invasion of virulent protozoans into epithelia. The versatility of this system and its higher degree of control in comparison with both traditional explant microscopy and in vivo two photon imaging solutions make it a valuable and easy-to-use addition to other current imaging techniques.