Stereotactic body radiation therapy for stage I non-small cell lung carcinomas: Moderate hypofractionation optimizes outcome

OBJECTIVES

In case of inoperability or refusal of surgery, stereotactic body radiation therapy (SBRT) is the most effective treatment for a stage I non-small cell lung carcinoma (NSCLC). The results obtained by this irradiation technique are considerably superior to those observed in the time of conventional 3D irradiation and its toxicities are much less important, which makes it possible in elderly patients, or those presenting cardio-pulmonary comorbidities and a poor perfomance status.

MATERIALS AND METHODS

This study is a retrospective analysis of 90 patients who underwent SBRT for a stage I NSCLC between 2010 and 2015. Its purpose is to describe its effectiveness in term of overall survival (OS), specific survival (SS), local control (LC), regional control (RC) and metastatic control (MC) as well as their prognostic factors, and its tolerance.

RESULTS

LC, RC, MC as well as OS and SS rate at 4 years were comparable to the main prospective studies, respectively 89%, 92%, 70%, 33% and 66%. No LC prognostic factor could be identified. Radiation pneumonitis was observed with a rate of 61.5%, of which 56% were asymptomatic, and 4% of the patients had a rib fracture.

CONCLUSIONS

SBRT is an efficient and well-tolerated treatment for stage I non-small cell lung carcinomas.

Limited Long-Term Impact of Insect Venom Immunotherapy on the Micro-RNA Landscape in Whole Blood

OBJECTIVE

To perform a genome-wide characterization of changes in microRNA (miRNA) expression during the course of venom immunotherapy (VIT).

METHODS

miRNA was isolated from the whole-blood of 13 allergic patients and 14 controls, who experienced no allergic reaction upon stings by honeybees and wasps. We analyzed 2549 miRNAs from the whole blood of these patients prior to VIT and 12 months after the start of VIT. The results for differential expression obtained on a microarray platform were confirmed by quantitative real-time PCR. Out of the 13 patients, 8 had a negative allergic reaction with VIT, thus indicating that this approach was successful.

RESULTS

By comparing time points before and 12 months after ultrarush VIT, correlation analysis and principal component analysis both indicated a limited effect of VIT on the overall miRNA expression pattern. Volcano plot analysis based on raw P values revealed few deregulated miRNAs, most of which were increasingly expressed after VIT as compared with before VIT. Based on the 50 most altered miRNAs, no clear clustering was observed before or after VIT.

CONCLUSIONS

Our results indicate an overall reduced effect of VIT on the miRNA expression pattern in whole blood.

Physical contact between mesenchymal stem cells and endothelial precursors induces distinct signatures with relevance to the very early phase of regeneration

Multipotent adult stem cells/precursor cells, especially of the mesenchymal and endothelial lineage, may have great potential for bone tissue engineering. Although their potential is highly recognized, not much is known about the underlying molecular mechanisms that initiate the regeneration process, connect osteogenesis, and angiogenesis and, finally, orchestrate renewal of bone tissue. Our study addressed these questions by generating two in vitro cell culture models to examine the changes in the global gene expression patterns of endothelial precursor cells and mesenchymal stem cells after 24 hours of either humoral (conditioned medium) or direct cell-cell interaction (co-culture). Endothelial precursor cells were isolated from human buffy coat and mesenchymal stem cells from the bone marrow of the femoral head. The comparison of the treated and control cells by microarray analyses revealed in total more than 1500 regulated genes, which were analyzed for their affiliation to angiogenesis and osteogenesis. Expression array analyses at the RNA and protein level revealed data with respect to regulated genes, pathways and targets that may represent a valid basis for further dissection of the systems biology of regeneration processes. It may also be helpful for the reconstitution of the natural composition of a regenerative microenvironment when targeting tissue regeneration both in vitro and in situ.

Random Mutagenesis, Clonal Events, and Embryonic or Somatic Origin Determine the mtDNA Variant Type and Load in Human Pluripotent Stem Cells

In this study, we deep-sequenced the mtDNA of human embryonic and induced pluripotent stem cells (hESCs and hiPSCs) and their source cells and found that the majority of variants pre-existed in the cells used to establish the lines. Early-passage hESCs carried few and low-load heteroplasmic variants, similar to those identified in oocytes and inner cell masses. The number and heteroplasmic loads of these variants increased with prolonged cell culture. The study of 120 individual cells of early- and late-passage hESCs revealed a significant diversity in mtDNA heteroplasmic variants at the single-cell level and that the variants that increase during time in culture are always passenger to the appearance of chromosomal abnormalities. We found that early-passage hiPSCs carry much higher loads of mtDNA variants than hESCs, which single-fibroblast sequencing proved pre-existed in the source cells. Finally, we show that these variants are stably transmitted during short-term differentiation.

[Radiotherapy of bone metastases in France: A descriptive monocentric retrospective study]

PURPOSE

Bone metastases cause pain and affect patients' quality of life. Radiation therapy is one of the reference analgesic treatments. The objective of this study was to compare the current practices of a French radiotherapy department for the treatment of uncomplicated bone metastases with data from the literature in order to improve and optimize the management of patients.

MATERIAL AND METHODS

A retrospective monocentric study of patients who underwent palliative irradiation of uncomplicated bone metastases was performed.

RESULTS

Ninety-one patients had 116 treatments of uncomplicated bone metastases between January 2014 and December 2015, including 44 men (48%) and 47 women (52%) with an average age of 63years (25-88years). Primary tumours most commonly found were breast cancer (35%), lung cancer (16%) and prostate cancer (12%). The regimens used were in 29% of cases 30Gy in ten fractions (group 30Gy), in 21% of cases 20Gy in five fractions (group 20Gy), in 22% of cases 8Gy in one fraction (group 8Gy) and in 28% of cases 23.31Gy in three fractions of stereotactic body irradiation (stereotactic group). The general condition of the patient (P<0.001), pain score and analgesic (P<0.001), oligometastatic profile (P=0.003) and practitioner experience (P<0.001) were factors influencing the choice of the regimen irradiation. Age (P=0.46), sex (P=0.14), anticancer treatments (P=0.56), concomitant hospitalization (P=0.14) and the distance between the radiotherapy centre and home (P=0.87) did not influence the decision significantly. A total of three cases of spinal compression and one case of post-therapeutic fracture were observed, occurring between one and 128days and 577days after irradiation, respectively. Eight percent of all irradiated metastases were reirradiated with a delay ranging between 13 and 434days after the first irradiation. The re-irradiation rate was significantly higher after 8Gy (P=0.02). The rate of death was significantly lower in the stereotactic arm (P<0.001) and overall survival was significantly greater in the stereotactic arm (P<0.001).

CONCLUSION

This study showed that patients' analysed was comparable to the population of different studies. Predictive factors for the choice of the treatment regimen were identified. Non-fractionnated therapy was underutilised while stereotactic treatment was increasingly prescribed, showing an evolution in the management of patients.

Genetic and epigenetic factors which modulate differentiation propensity in human pluripotent stem cells

BACKGROUND

Human pluripotent stem cell (hPSC) lines are known to have a bias in their differentiation. This gives individual cell lines a propensity to preferentially differentiate towards one germ layer or cell type over others. Chromosomal aberrations, mitochondrial mutations, genetic diversity and epigenetic variance are the main drivers of this phenomenon, and can lead to a wide range of phenotypes.

OBJECTIVE AND RATIONALE

Our aim is to provide a comprehensive overview of the different factors which influence differentiation propensity. Specifically, we sought to highlight known genetic variances and their mechanisms, in addition to more general observations from larger abnormalities. Furthermore, we wanted to provide an up-to-date list of a growing number of predictive indicators which are able to identify differentiation propensity before the initiation of differentiation. As differentiation propensity can lead to difficulties in both research as well as clinical translation, our thorough overview could be a useful tool.

SEARCH METHODS

Combinations of the following key words were applied as search criteria in the PubMed database: embryonic stem cells, induced pluripotent stem cells, differentiation propensity (also: potential, efficiency, capacity, bias, variability), epigenetics, chromosomal abnormalities, genetic aberrations, X chromosome inactivation, mitochondrial function, mitochondrial metabolism, genetic diversity, reprogramming, predictive marker, residual stem cell, clinic. Only studies in English were included, ranging from 2000 to 2017, with a majority ranging from 2010 to 1017. Further manuscripts were added from cross-references.

OUTCOMES

Differentiation propensity is affected by a wide variety of (epi)genetic factors. These factors clearly lead to a loss of differentiation capacity, preference towards certain cell types and oftentimes, phenotypes which begin to resemble cancer. Broad changes in (epi)genetics, such as aneuploidies or wide-ranging modifications to the epigenetic landscape tend to lead to extensive, less definite changes in differentiation capacity, whereas more specific abnormalities often have precise ramifications in which certain cell types become more preferential. Furthermore, there appears to be a greater, though often less considered, contribution to differentiation propensity by factors such as mitochondria and inherent genetic diversity. Varied differentiation capacity can also lead to potential consequences in the clinical translation of hPSC, including the occurrence of residual undifferentiated stem cells, and the transplantation of potentially transformed cells.

WIDER IMPLICATIONS

As hPSC continue to advance towards the clinic, our understanding of them progresses as well. As a result, the challenges faced become more numerous, but also more clear. If the transition to the clinic is to be achieved with a minimum number of potential setbacks, thorough evaluation of the cells will be an absolute necessity. Altered differentiation propensity represents at least one such hurdle, for which researchers and eventually clinicians will need to find solutions. Already, steps are being taken to tackle the issue, though further research will be required to evaluate any long-term risks it poses.

The characterization of the circadian clock in the olive fly Bactrocera oleae (Diptera: Tephritidae) reveals a Drosophila-like organization

The olive fruit fly, Bactrocera oleae, is the single most important pest for the majority of olive plantations. Oxitec's self-limiting olive fly technology (OX3097D-Bol) offers an alternative management approach to this insect pest. Because of previously reported asynchrony in the mating time of wild and laboratory strains, we have characterized the olive fly circadian clock applying molecular, evolutionary, anatomical and behavioural approaches. Here we demonstrate that the olive fly clock relies on a Drosophila melanogaster-like organization and that OX3097D-Bol carries a functional clock similar to wild-type strains, confirming its suitability for operational use.

BMP-2 gene activated muscle tissue fragments for osteochondral defect regeneration in the rabbit knee

BACKGROUND

Previously published data indicate that BMP-2 gene activated muscle tissue grafts can repair large bone defects in rats. This innovative abbreviated ex vivo gene therapy is appealing because it does not require elaborative and time-consuming extraction and expansion of cells. Hence, in the present study, we evaluated the potential of this expedited tissue engineering approach for regenerating osteochondral defects in rabbits.

METHODS

Autologous muscle tissue grafts from female White New Zealand rabbits were directly transduced with an adenoviral BMP-2 vector or remained unmodified. Osteochondral defects in the medial condyle of rabbit knees were treated with either BMP-2 activated muscle tissue implants or unmodified muscle tissue or remained empty. After 13 weeks, repair of osteochondral defects was examined by biomechanical indentation testing and by histology/imunohistochemistry applying an extended O'Driscoll scoring system and histomorphometry.

RESULTS

Biomechanical investigations revealed a trend towards slightly improved mechanical properties of the group receiving BMP-2 activated muscle tissue compared to unmodified muscle treatment and empty defect controls. However, a statistically significant difference was noted only between BMP-2 muscle and unmodified muscle treatment. Also, histological evaluation resulted in slightly higher histological scores and improved collagen I/II ratio without statistical significance in the BMP-2 treatment group. Histomorphometry indicated enhanced repair of subchondral bone after treatment with BMP-2 muscle, with a significantly larger bone area compared to untreated defects.

CONCLUSIONS

Gene activated muscle tissue grafts showed potential for osteochondral defect repair. There is room for improvement via the use of appropriate growth factor combinations.

Release from prey preservation behavior via prey switch allowed diversification of cuticular hydrocarbon profiles in digger wasps

The cuticle of insects is covered by a layer of hydrocarbons (CHC), whose original function is the protection from desiccation and pathogens. However, in most insects CHC profiles are species specific. While this variability among species was largely linked to communication and recognition functions, additional selective forces may shape insect CHC profiles. Here, we show that in Philanthinae digger wasps (Crabronidae) the CHC profile coevolved with a peculiar brood-care strategy. In particular, we found that the behavior to embalm prey stored in the nest with hydrocarbons is adaptive to protect larval food from fungi in those species hunting for Hymenoptera. The prey embalming secretion is identical in composition to the alkene-dominated CHC profile in these species, suggesting that their profile is adaptively conserved for this purpose. In contrast, prey embalming is not required in those species that switched to Coleoptera as prey. Released from this chemical brood-care strategy, Coleoptera-hunting species considerably diversified their CHC profiles. Differential needs to successfully protect prey types used as larval food have thus driven the diversification of CHCs profiles of female Philanthinae wasps. To the best of our knowledge, this is the first evidence of a direct link between selection pressure for food preservation and CHC diversity.

Impact of synaptic localization and subunit composition of ionotropic glutamate receptors on synaptic function: modeling and simulation studies

Ionotropic NMDA and AMPA glutamate receptors (iGluRs) play important roles in synaptic function under physiological and pathological conditions. iGluRs sub-synaptic localization and subunit composition are dynamically regulated by activity-dependent insertion and internalization. However, understanding the impact on synaptic transmission of changes in composition and localization of iGluRs is difficult to address experimentally. To address this question, we developed a detailed computational model of glutamatergic synapses, including spine and dendritic compartments, elementary models of subtypes of NMDA and AMPA receptors, glial glutamate transporters, intracellular calcium and a calcium-dependent signaling cascade underlying the development of long-term potentiation (LTP). These synapses were distributed on a neuron model and numerical simulations were performed to assess the impact of changes in composition and localization (synaptic vs extrasynaptic) of iGluRs on synaptic transmission and plasticity following various patterns of presynaptic stimulation. In addition, the effects of various pharmacological compounds targeting NMDARs or AMPARs were determined. Our results showed that changes in NMDAR localization have a greater impact on synaptic plasticity than changes in AMPARs. Moreover, the results suggest that modulators of AMPA and NMDA receptors have differential effects on restoring synaptic plasticity under different experimental situations mimicking various human diseases.

[Risk of radionecrosis after hypofractionated stereotactic radiotherapy targeting the postoperative resection cavity of brain metastases]

PURPOSE

To investigate the factors that potentially lead to brain radionecrosis after hypofractionated stereotactic radiotherapy targeting the postoperative resection cavity of brain metastases.

METHODS AND MATERIALS

A retrospective analysis conducted in two French centres, was performed in patients treated with trifractionated stereotactic radiotherapy (3×7.7Gy prescribed to the 70% isodose line) for resected brain metastases. Patients with previous whole-brain irradiation were excluded of the analysis. Radionecrosis was diagnosed according to a combination of criteria including clinical, serial imaging or, in some cases, histology. Univariate and multivariate analyses were performed to determine the predictive factors of radionecrosis including clinical and dosimetric variables such as volume of brain receiving a specific dose (V_8Gy-V_22Gy).

RESULTS

One hundred eighty-one patients, with a total of 189 cavities were treated between March 2008 and February 2015. Thirty-five patients (18.5%) developed radionecrosis after a median follow-up of 15 months (range: 3-38 months) after hypofractionated stereotactic radiotherapy. One third of patients with radionecrosis were symptomatic. Multivariate analysis showed that infra-tentorial location was predictive of radionecrosis (hazard ratio [HR]: 2.97; 95% confidence interval [95% CI]: 1.47-6.01; P=0.0025). None V_8Gy-V_22Gy was associated with appearance of radionecrosis, even if V_14Gy trended toward significance (P=0.059).

CONCLUSION

Analysis of patients and treatment variables revealed that infratentorial location of brain metastases was predictive for radionecrosis after hypofractionated stereotactic radiotherapy for postoperative resection cavities.

biojs-io-biom, a BioJS component for handling data in Biological Observation Matrix (BIOM) format

The Biological Observation Matrix (BIOM) format is widely used to store data from high-throughput studies. It aims at increasing interoperability of bioinformatic tools that process this data. However, due to multiple versions and implementation details, working with this format can be tricky. Currently, libraries in Python, R and Perl are available, whilst such for JavaScript are lacking. Here, we present a BioJS component for parsing BIOM data in all format versions. It supports import, modification, and export via a unified interface. This module aims to facilitate the development of web applications that use BIOM data. Finally, we demonstrate its usefulness by two applications that already use this component. Availability: https://github.com/molbiodiv/biojs-io-biom, https://dx.doi.org/10.5281/zenodo.218277.

Contact of myeloma cells induces a characteristic transcriptome signature in skeletal precursor cells -Implications for myeloma bone disease

Physical interaction of skeletal precursors with multiple myeloma cells has been shown to suppress their osteogenic potential while favoring their tumor-promoting features. Although several transcriptome analyses of myeloma patient-derived mesenchymal stem cells have displayed differences compared to their healthy counterparts, these analyses insufficiently reflect the signatures mediated by tumor cell contact, vary due to different methodologies, and lack results in lineage-committed precursors. To determine tumor cell contact-mediated changes on skeletal precursors, we performed transcriptome analyses of mesenchymal stem cells and osteogenic precursor cells cultured in contact with the myeloma cell line INA-6. Comparative analyses confirmed dysregulation of genes which code for known disease-relevant factors and additionally revealed upregulation of genes that are associated with plasma cell homing, adhesion, osteoclastogenesis, and angiogenesis. Osteoclast-derived coupling factors, a dysregulated adipogenic potential, and an imbalance in favor of anti-anabolic factors may play a role in the hampered osteoblast differentiation potential of mesenchymal stem cells. Angiopoietin-Like 4 (ANGPTL4) was selected from a list of differentially expressed genes as a myeloma cell contact-dependent target in skeletal precursor cells which warranted further functional analyses. Adhesion assays with full-length ANGPTL4-coated plates revealed a potential role of this protein in INA-6 cell attachment. This study expands knowledge of the myeloma cell contact-induced signature in the stromal compartment of myelomatous bones and thus offers potential targets that may allow detection and treatment of myeloma bone disease at an early stage.

Laboratory rearing of solitary bees and wasps

Ecological experiments often require standardized methods that exclude natural variation and allow manipulation of a single parameter. It has been shown that domesticated honey bee larvae are raisable in a controlled environment. Here we demonstrate that this approach is also transferable to wild solitary bees and wasps without inducing negative effects on their development. Wells may also be supplemented with the antibiotic substance oxytetracycline to control the presence of bacteria. The method thus provides a useful tool to investigate offspring recruitment and larval development in solitary bees and wasps, plus their responses to manipulation of factors as for example diets, toxins and microbiota.

Pollen DNA barcoding: current applications and future prospects

Identification of the species origin of pollen has many applications, including assessment of plant–pollinator networks, reconstruction of ancient plant communities, product authentication, allergen monitoring, and forensics. Such applications, however, have previously been limited by microscopy-based identification of pollen, which is slow, has low taxonomic resolution, and has few expert practitioners. One alternative is pollen DNA barcoding, which could overcome these issues. Recent studies demonstrate that both chloroplast and nuclear barcoding markers can be amplified from pollen. These recent validations of pollen metabarcoding indicate that now is the time for researchers in various fields to consider applying these methods to their research programs. In this paper, we review the nascent field of pollen DNA barcoding and discuss potential new applications of this technology, highlighting existing limitations and future research developments that will improve its utility in a wide range of applications.

bcgTree: automatized phylogenetic tree building from bacterial core genomes

The need for multi-gene analyses in scientific fields such as phylogenetics and DNA barcoding has increased in recent years. In particular, these approaches are increasingly important for differentiating bacterial species, where reliance on the standard 16S rDNA marker can result in poor resolution. Additionally, the assembly of bacterial genomes has become a standard task due to advances in next-generation sequencing technologies. We created a bioinformatic pipeline, bcgTree, which uses assembled bacterial genomes either from databases or own sequencing results from the user to reconstruct their phylogenetic history. The pipeline automatically extracts 107 essential single-copy core genes, found in a majority of bacteria, using hidden Markov models and performs a partitioned maximum-likelihood analysis. Here, we describe the workflow of bcgTree and, as a proof-of-concept, its usefulness in resolving the phylogeny of 293 publically available bacterial strains of the genus Lactobacillus. We also evaluate its performance in both low- and high-level taxonomy test sets. The tool is freely available at github ( https://github.com/iimog/bcgTree ) and our institutional homepage ( http://www.dna-analytics.biozentrum.uni-wuerzburg.de ).

Bacterial Diversity and Community Structure in Two Bornean Nepenthes Species with Differences in Nitrogen Acquisition Strategies

Carnivorous plants of the genus Nepenthes have been studied for over a century, but surprisingly little is known about associations with microorganisms. The two species Nepenthes rafflesiana and Nepenthes hemsleyana differ in their pitcher-mediated nutrient sources, sequestering nitrogen from arthropod prey and arthropods as well as bat faeces, respectively. We expected bacterial communities living in the pitchers to resemble this diet difference. Samples were taken from different parts of the pitchers (leaf, peristome, inside, outside, digestive fluid) of both species. Bacterial communities were determined using culture-independent high-throughput amplicon sequencing. Bacterial richness and community structure were similar in leaves, peristomes, inside and outside walls of both plant species. Regarding digestive fluids, bacterial richness was higher in N. hemsleyana than in N. rafflesiana. Additionally, digestive fluid communities were highly variable in structure, with strain-specific differences in community composition between replicates. Acidophilic taxa were mostly of low abundance, except the genus Acidocella, which strikingly reached extremely high levels in two N. rafflesiana fluids. In N. hemsleyana fluid, some taxa classified as vertebrate gut symbionts as well as saprophytes were enriched compared to N. rafflesiana, with saprophytes constituting potential competitors for nutrients. The high variation in community structure might be caused by a number of biotic and abiotic factors. Nitrogen-fixing bacteria were present in both study species, which might provide essential nutrients to the plant at times of low prey capture and/or rare encounters with bats.

Draft genome of the Arabidopsis thaliana phyllosphere bacterium, Williamsia sp. ARP1

The Gram-positive actinomycete Williamsia sp. ARP1 was originally isolated from the Arabidopsis thaliana phyllosphere. Here we describe the general physiological features of this microorganism together with the draft genome sequence and annotation. The 4,745,080 bp long genome contains 4434 protein-coding genes and 70 RNA genes. To our knowledge, this is only the second reported genome from the genus Williamsia and the first sequenced strain from the phyllosphere. The presented genomic information is interpreted in the context of an adaptation to the phyllosphere habitat.

The effect of BMP-7 gene activated muscle tissue implants on the repair of large segmental bone defects

BACKGROUND

This study was conducted in order to investigate the effect of Bone Morphogenetic Protein-7 (BMP-7) transduced muscle cells on bone formation and to further develop an innovative abbreviated ex vivo gene therapy for bone repair. As conventional ex vivo gene therapy methods require an elaborative and time-consuming extraction and expansion of cells we evaluated an expedited approach. Fragments of muscle tissue were directly activated by BMP-7 cDNA and implanted into bone defects.

METHODS

25 male, syngeneic Fischer 344 rats were used in the present study. Muscle tissue was harvested from two donor rats and either transduced with an adenovirus carrying the BMP-7 cDNA or remained unmodified. 5mm osseous defects in the right femora of 23 rats were treated with either unmodified muscle tissue (control group) or BMP-7 activated muscle tissue (treatment group). Six weeks after surgery, rat femora were evaluated by radiographs, micro-computed tomography (μCT) and histology.

RESULTS

Implantation of BMP-7 activated muscle grafts led to bony bridging in 5 out of 12 defects (41.7%) and to bone formation without bridging in 2 out of 12 defects. In 2 femoral defects of this group radiographs, μCT-imaging and histology did not reveal significant mineralization. Three animals of the BMP-7 treatment group had to be euthanized due to serious wound infection. The bone volume of the treatment group was significantly (p=0.007) higher compared to the control group.

CONCLUSION

This study shows that BMP-7 gene activated muscle fragments have the potential to regenerate critical-size segmental bone defects in rats. However, further development of this promising expedited treatment modality is required to improve the healing rate and to investigate if the high infection rate is related to treatment with BMP-7 activated muscle grafts.

Genome-wide copy number profiling to detect gene amplifications in neural progenitor cells

DNA sequence amplification occurs at defined stages during normal development in amphibians and flies and seems to be restricted in humans to drug-resistant and tumor cells only. We used array-CGH to discover copy number changes including gene amplifications and deletions during differentiation of human neural progenitor cells. Here, we describe cell culture features, DNA extraction, and comparative genomic hybridization (CGH) analysis tailored towards the identification of genomic copy number changes. Further detailed analysis of amplified chromosome regions associated with this experiment, was published by Fischer and colleagues in PLOS One in 2012 (Fischer et al., 2012). We provide detailed information on deleted chromosome regions during differentiation and give an overview on copy number changes during differentiation induction for two representative chromosome regions.

Reptiles as Reservoirs of Bacterial Infections: Real Threat or Methodological Bias?

Bacterial infections secondary to snakebites and human pathogens (e.g., Salmonella) have been linked to the oral microbiota of snakes and pet reptiles. Based on culture-dependent studies, it is speculated that snakes' oral microbiota reflects the fecal flora of their ingested preys. However, cultured-based techniques have been shown to be limited as they fail to identify unculturable microorganisms which represent the vast majority of the microbial diversity. Here, we used culture-independent high-throughput sequencing to identify reptile-associated pathogens and to characterize the oral microbial community of five snakes, one gecko, and two terrapins. Few potential human pathogens were detected at extremely low frequencies. Moreover, bacterial taxa represented in the snake's oral cavity bore little resemblance to their preys' fecal microbiota. Overall, we found distinct, highly diverse microbial communities with consistent, species-specific patterns contrary to previous culture-based studies. Our study does not support the widely held assumption that reptiles' oral cavity acts as pathogen reservoir and provides important insights for future research.

Experimental computer tomograph

The computed tomography is one of the most important medical instruments, allowing the non-invasive visualization of cross sections which are free from superpositions. Since 2000 an experimental computer tomo-graph of the third generation for the purpose of education and research was set up and further developed. Besides the mechanical construction design reconstruction algorithms, including certain corrections of the measured data were developed and implemented. In 2013 iterative reconstruction methods were investigated and implemented for advanced reconstructions and dose reduction using various ray tracing algorithms. The new reconstruction technique leads to improvements in image quality and low dose reconstructions.