Transport of dust across the Solar System: Constraints on the spatial origin of individual micrometeorites from cosmic-ray exposure

The origin of micrometeorites (MMs) from asteroids and comets is well-established, but the relative contribution from these two classes remains poorly resolved. Likewise, determining the precise origin of individual MMs is an open challenge. Here, cosmic-ray exposure ages are used to resolve the spatial origins of 12 MMs collected from urban areas and Antarctica. Their 26Al and 10Be concentration, produced during cosmic-ray irradiation in space, were measured by accelerator mass spectrometry. These data are compared to results from a model simulating the transport and irradiation of the MM precursors in space. This model, for the first time, considers a variety of orbits, precursor particle sizes, compositions and densities and incorporates non-isotropic solar and galactic cosmic-ray flux profiles, depth-dependent production rates, as well as spherical evaporation during atmospheric entry. While the origin for six MMs remains ambiguous, two MMs show a preferential tendency towards an origin in the Inner Solar System (Near Earth Objects to the Asteroid Belt) and four towards an origin in the Outer Solar System (Jupiter Family Comets to the Kuiper Belt). These findings challenge the notion that dust originating from the Outer Solar System is unlikely to survive long-term transport and delivery to the terrestrial planets. This article is part of the theme issue 'Dust in the Solar System and beyond'.

Modern Tools for Modern Brachytherapy

This review aims to showcase the brachytherapy tools and technologies that have emerged during the last 10 years. Soft-tissue contrast using magnetic resonance and ultrasound imaging has seen enormous growth in use to plan all forms of brachytherapy. The era of image-guided brachytherapy has encouraged the development of advanced applicators and given rise to the growth of individualised 3D printing to achieve reproducible and predictable implants. These advances increase the quality of implants to better direct radiation to target volumes while sparing normal tissue. Applicator reconstruction has moved beyond manual digitising, to drag and drop of three-dimensional applicator models with embedded pre-defined source pathways, ready for auto-recognition and automation. The simplified TG-43 dose calculation formalism directly linked to reference air kerma rate of high-energy sources in the medium water remains clinically robust. Model-based dose calculation algorithms accounting for tissue heterogeneity and applicator material will advance the field of brachytherapy dosimetry to become more clinically accurate. Improved dose-optimising toolkits contribute to the real-time and adaptive planning portfolio that harmonises and expedites the entire image-guided brachytherapy process. Traditional planning strategies remain relevant to validate emerging technologies and should continue to be incorporated in practice, particularly for cervical cancer. Overall, technological developments need commissioning and validation to make the best use of the advanced features by understanding their strengths and limitations. Brachytherapy has become high-tech and modern by respecting tradition and remaining accessible to all.

Multihost Transmission of Schistosoma mansoni in Senegal, 2015-2018

In West Africa, Schistosoma spp. are capable of infecting multiple definitive hosts, a lifecycle feature that may complicate schistosomiasis control. We characterized the evolutionary relationships among multiple Schistosoma mansoni isolates collected from snails (intermediate hosts), humans (definitive hosts), and rodents (definitive hosts) in Senegal. On a local scale, diagnosis of S. mansoni infection ranged 3.8%-44.8% in school-aged children, 1.7%-52.6% in Mastomys huberti mice, and 1.8%-7.1% in Biomphalaria pfeifferi snails. Our phylogenetic framework confirmed the presence of multiple S. mansoni lineages that could infect both humans and rodents; divergence times of these lineages varied (0.13-0.02 million years ago). We propose that extensive movement of persons across West Africa might have contributed to the establishment of these various multihost S. mansoni clades. High S. mansoni prevalence in rodents at transmission sites frequented by humans further highlights the implications that alternative hosts could have on future public health interventions.

Three cooperative mechanisms required for recovery after brain damage

Stroke is one of the main causes of human disabilities. Experimental observations indicate that several mechanisms are activated during the recovery of functional activity after a stroke. Here we unveil how the brain recovers by explaining the role played by three mechanisms: Plastic adaptation, hyperexcitability and synaptogenesis. We consider two different damages in a neural network: A diffuse damage that simply causes the reduction of the effective system size and a localized damage, a stroke, that strongly alters the spontaneous activity of the system. Recovery mechanisms observed experimentally are implemented both separately and in a combined way. Interestingly, each mechanism contributes to the recovery to a limited extent. Only the combined application of all three together is able to recover the spontaneous activity of the undamaged system. This explains why the brain triggers independent mechanisms, whose cooperation is the fundamental ingredient for the system’s recovery.

Dynamical diffraction effects on the geometric phase of inhomogeneous strain fields

In specimens with an inhomogeneous displacement field in electron beam direction dynamical diffraction effects lead to complex non-linear properties of the diffracted electron wave. Consequently, the diffracted beam's phase contains information about the inhomogeneous displacement field. These phases are experimentally and theoretically investigated under different excitation errors and specimen thicknesses as well as for different depths of the displacement field. An inclined InGaAs layer with a larger lattice constant than the surrounding GaAs matrix serves as controlled displacement field, which is inhomogeneous in electron beam direction with a continuously changing depth. The phase and amplitude of the diffracted beam are measured by dark-field electron holography. The measurements agree with calculations performed by numerical propagation of the electron wave using the Darwin-Howie-Whelan equations. A strong dependency on the excitation conditions is found showing that the interplay between dynamical effects and the strain field must be considered in the interpretation of the geometric phase.

Evaluation of DNA Extraction Methods on Individual Helminth Egg and Larval Stages for Whole-Genome Sequencing

Whole-genome sequencing is being rapidly applied to the study of helminth genomes, including de novo genome assembly, population genetics, and diagnostic applications. Although late-stage juvenile and adult parasites typically produce sufficient DNA for molecular analyses, these parasitic stages are almost always inaccessible in the live host; immature life stages found in the environment for which samples can be collected non-invasively offer a potential alternative; however, these samples typically yield very low quantities of DNA, can be environmentally resistant, and are susceptible to contamination, often from bacterial or host DNA. Here, we have tested five low-input DNA extraction protocols together with a low-input sequencing library protocol to assess the feasibility of whole-genome sequencing of individual immature helminth samples. These approaches do not use whole-genome amplification, a common but costly approach to increase the yield of low-input samples. We first tested individual parasites from two species spotted onto FTA cards-egg and L1 stages of Haemonchus contortus and miracidia of Schistosoma mansoni-before further testing on an additional five species-Ancylostoma caninum, Ascaridia dissimilis, Dirofilaria immitis, Strongyloides stercoralis, and Trichuris muris-with an optimal protocol. A sixth species-Dracunculus medinensis-was included for comparison. Whole-genome sequencing followed by analyses to determine the proportion of on- and off-target mapping revealed successful sample preparations for six of the eight species tested with variation both between species and between different life stages from some species described. These results demonstrate the feasibility of whole-genome sequencing of individual parasites, and highlight a new avenue toward generating sensitive, specific, and information-rich data for the diagnosis and surveillance of helminths.

Males as somatic investment in a parthenogenetic nematode

We report the reproductive strategy of the nematode Mesorhabditis belari This species produces only 9% males, whose sperm is necessary to fertilize and activate the eggs. However, most of the fertilized eggs develop without using the sperm DNA and produce female individuals. Only in 9% of eggs is the male DNA utilized, producing sons. We found that mixing of parental genomes only gives rise to males because the Y-bearing sperm of males are much more competent than the X-bearing sperm for penetrating the eggs. In this previously unrecognized strategy, asexual females produce few sexual males whose genes never reenter the female pool. Here, production of males is of interest only if sons are more likely to mate with their sisters. Using game theory, we show that in this context, the production of 9% males by M. belari females is an evolutionary stable strategy.

N6-Methyladenosine detected in RNA of testicular germ cell tumors is controlled by METTL3, ALKBH5, YTHDC1/F1/F2, and HNRNPC as writers, erasers, and readers

BACKGROUND

Type II testicular germ cell tumors (GCTs) arise from a common precursor lesion (germ cell neoplasia in situ) and are stratified into seminomas and non-seminomas, which differ considerably in morphology, gene expression, and epigenetic landscape. The N6-methyladenosine (6mA) epigenetic modification is the most abundant modification in mRNA and is also detectable in eukaryotic DNA. The functional role of 6mA is not fully understood, but 6mA residues may influence transcription by affecting splicing, miRNA processing, and mRNA stability. Additionally, the methyl group of 6mA destabilizes Watson-Crick base-pairing affecting RNA structure and protein binding.

OBJECTIVES

Here, we analyzed the presence of the 6mA epigenetic modification in germ cells and GCT tissues and cell lines.

MATERIALS AND METHODS

We screened for the presence of 6mA in DNA and RNA by immunohistochemistry, mass spectrometry or ELISA-based quantification assays. Additionally, expression of 6mA writer-, eraser- and reader-factors was analyzed by microarrays, qRT-PCR, western blotting and screening of public databases.

RESULTS

We demonstrate that 6mA is detectable in RNA, but not DNA, of GCT cell lines and tissues, fibroblasts, and Sertoli cells as well as germ cells of different developmental stages. Based on expression analyses, our results suggest METTL3, ALKBH5, YTHDC1, YTHDF1, YTHDF2 and HNRNPC as main writers, erasers, and readers of the 6mA modification in GCTs.

DISCUSSION

Owing to the lack of 6mA in DNA of GCTs, a functional role in regulating DNA transcription can be excluded. Interestingly, expression levels of 6mA regulators are comparable between tumor and normal tissues/cells, suggesting a similar mechanism of 6mA regulation in RNA. Finally, we demonstrate that 6mA levels in RNA increase upon differentiation of GCT cell lines, suggesting a role of 6mA in cell fate decisions.

CONCLUSION

In summary, our data provide the starting point for further experiments deciphering the role of 6mA in the RNA of GCTs.

Pattern recognition with neuronal avalanche dynamics

Pattern recognition is a fundamental neuronal process which enables a cortical system to interpret visual stimuli. How the brain learns to recognize patterns is, however, an unsolved problem. The frequently employed method of back propagation excels at this task but has been found to be unbiological in many aspects. In this Rapid Communication we achieve pattern recognition tasks in a biologically, fully consistent framework. We consider a neuronal network exhibiting avalanche dynamics, as observed experimentally, and implement negative feedback signals. These are chemical signals, such as dopamine, which mediate synaptic plasticity and sculpt the network to achieve certain tasks. The system is able to distinguish horizontal and vertical lines with high accuracy, as well as to perform well at the more complicated task of handwritten digit recognition. Resulting from the learning mechanism, spatially separate activity regions emerge, as observed in the primary visual cortex using functional magnetic resonance imaging techniques. The results therefore suggest that negative feedback signals offer an explanation for the emergence of distinct activity areas in the visual cortex.

Improving the annotation of the Heterorhabditis bacteriophora genome

Background

Genome assembly and annotation remain exacting tasks. As the tools available for these tasks improve, it is useful to return to data produced with earlier techniques to assess their credibility and correctness. The entomopathogenic nematode Heterorhabditis bacteriophora is widely used to control insect pests in horticulture. The genome sequence for this species was reported to encode an unusually high proportion of unique proteins and a paucity of secreted proteins compared to other related nematodes.

Findings

We revisited the H. bacteriophora genome assembly and gene predictions to determine whether these unusual characteristics were biological or methodological in origin. We mapped an independent resequencing dataset to the genome and used the blobtools pipeline to identify potential contaminants. While present (0.2% of the genome span, 0.4% of predicted proteins), assembly contamination was not significant.

Conclusions

Re-prediction of the gene set using BRAKER1 and published transcriptome data generated a predicted proteome that was very different from the published one. The new gene set had a much reduced complement of unique proteins, better completeness values that were in line with other related species’ genomes, and an increased number of proteins predicted to be secreted. It is thus likely that methodological issues drove the apparent uniqueness of the initial H. bacteriophora genome annotation and that similar contamination and misannotation issues affect other published genome assemblies.

Drug-induced inhibition of phosphorylation of STAT5 overrides drug resistance in neoplastic mast cells

Systemic mastocytosis (SM) is a mast cell (MC) neoplasm with complex pathology and a variable clinical course. In aggressive SM (ASM) and MC leukemia (MCL) responses to conventional drugs are poor and the prognosis is dismal. R763 is a multi-kinase inhibitor that blocks the activity of Aurora-kinase-A/B, ABL1, AKT and FLT3. We examined the effects of R763 on proliferation and survival of neoplastic MC. R763 produced dose-dependent inhibition of proliferation in the human MC lines HMC-1.1 (IC₅₀ 5-50 nM), HMC-1.2 (IC₅₀ 1-10 nM), ROSA^{KIT WT} (IC₅₀ 1-10 nM), ROSA^{KIT D816V} (IC₅₀ 50-500 nM) and MCPV-1.1 (IC₅₀ 100-1000 nM). Moreover, R763 induced growth inhibition in primary neoplastic MC in patients with ASM and MCL. Growth-inhibitory effects of R763 were accompanied by signs of apoptosis and a G2/M cell cycle arrest. R763 also inhibited phosphorylation of KIT, BTK, AKT and STAT5 in neoplastic MC. The most sensitive target appeared to be STAT5. In fact, tyrosine phosphorylation of STAT5 was inhibited by R763 at 10 nM. At this low concentration, R763 produced synergistic growth-inhibitory effects on neoplastic MC when combined with midostaurin or dasatinib. Together, R763 is a novel promising multi-kinase inhibitor that blocks STAT5 activation and thereby overrides drug-resistance in neoplastic MC.

European Hernia Society guidelines on prevention and treatment of parastomal hernias

BACKGROUND

International guidelines on the prevention and treatment of parastomal hernias are lacking. The European Hernia Society therefore implemented a Clinical Practice Guideline development project.

METHODS

The guidelines development group consisted of general, hernia and colorectal surgeons, a biostatistician and a biologist, from 14 European countries. These guidelines conformed to the AGREE II standards and the GRADE methodology. The databases of MEDLINE, CINAHL, CENTRAL and the gray literature through OpenGrey were searched. Quality assessment was performed using Scottish Intercollegiate Guidelines Network checklists. The guidelines were presented at the 38th European Hernia Society Congress and each key question was evaluated in a consensus voting of congress participants.

RESULTS

End colostomy is associated with a higher incidence of parastomal hernia, compared to other types of stomas. Clinical examination is necessary for the diagnosis of parastomal hernia, whereas computed tomography scan or ultrasonography may be performed in cases of diagnostic uncertainty. Currently available classifications are not validated; however, we suggest the use of the European Hernia Society classification for uniform research reporting. There is insufficient evidence on the policy of watchful waiting, the route and location of stoma construction, and the size of the aperture. The use of a prophylactic synthetic non-absorbable mesh upon construction of an end colostomy is strongly recommended. No such recommendation can be made for other types of stomas at present. It is strongly recommended to avoid performing a suture repair for elective parastomal hernia. So far, there is no sufficient comparative evidence on specific techniques, open or laparoscopic surgery and specific mesh types. However, a mesh without a hole is suggested in preference to a keyhole mesh when laparoscopic repair is performed.

CONCLUSION

An evidence-based approach to the diagnosis and management of parastomal hernias reveals the lack of evidence on several topics, which need to be addressed by multicenter trials. Parastomal hernia prevention using a prophylactic mesh for end colostomies reduces parastomal herniation. Clinical outcomes should be audited and adverse events must be reported.

Effekte der telefonischen Nachsorge in der onkologischen Rehabilitation nach Brustkrebs – Ergebnisse einer randomisierten Studie

Hintergrund Die Effekte und Evidenz der onkologischen Rehabilitation und von Nachsorgeprogrammen nach onkologischer Erkrankung werden unverändert kontrovers beurteilt. Ziel dieser Studie war daher die Evaluation der Durchführbarkeit und der Nutzen einer telefonischen Nachsorge zur Verbesserung von therapeutischen Effekten nach onkologischer Rehabilitation.

Methodik 172 Brustkrebspatientinnen (27–54 Jahre) wurden zu Beginn der stationären Rehabilitation (T1), zu Reha-Ende (T2) und 6 Monate nach Reha-Ende (T3) (Kontroll-Gruppe ohne, Interventionsgruppe mit telefonischer Nachsorge in 4-wöchigen Abständen) mit einem Fragebogenpaket untersucht (u. a. IRES-24. HADS, LZI, Emotional Thermometer, Fragebogen „Return-to-work).

Ergebnisse Für den IRES-24 ergab sich in der 2-faktoriellen Varianzanalyse ein signifikanter Haupteffekt für den Messzeitpunkt (F(2,116)=40,49, p<0,01), ebenso für den HADS-Angst- sowie Depressionswert (F(2,117)=31,50, p<0,01; (F(2,11 6)=31,19, p<0,01), jedoch keine signifikanten Unterschiede in Abhängigkeit von der Intervention (KG vs. NG; (F(2,116)=3,03, p=0,059).

Schlussfolgerung Eine Verbesserung der Wirkung durch die telefonische Nachsorge ließ sich nicht belegen. Ursächlich hierfür könnte neben einer zu geringen Dosis der Intervention auch die in den letzten Jahren schon umgesetzten multimodalen Therapiekonzepte in der onkologischen Rehabilitation sein.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Predictors of early retirement after cancer rehabilitation-a longitudinal study

This longitudinal study was designed to assess patients' desire for early retirement and investigate which cancer-related and psychosocial characteristics are associated with early retirement. We assessed 750 cancer patients at the beginning (t₀ ) and end (t₁ ) of, and 12 months after (t₂ ) inpatient cancer rehabilitation. At t₀ , 22% had a desire to retire early. These patients reported significantly longer sick leave periods, less favourable workplace environments, lower work ability, higher psychological distress and lower quality of life than other patients. At t₂ , 12.5% of patients received temporary or permanent early retirement pensions. Of all patients with a desire for early retirement at t₀ , 43% had returned to work at t₂ . This subgroup had a significantly lower physical quality of life than other patients returning to work. The most influential predictors of early retirement were being on sick leave (OR = 6.50, 95% CI = 1.97-21.47) and a desire for early retirement (OR = 5.61, 95% CI = 2.73-11.52). Inverse predictors of early retirement were cancer remission (OR = 0.23, 95% CI = 0.10-0.53), perceived productivity (OR = 0.38, 95% CI = 0.18-0.83), work satisfaction (OR = 0.36, 95% CI = 0.17-0.77) and mental quality of life (OR = 0.94, 95% CI = 0.91-0.98). This underlines the need for cancer-specific multi-professional rehabilitation and occupational therapy programmes.

Plastic and evolutionary responses to heat stress in a temperate dung fly: negative correlation between basal and induced heat tolerance?

Extreme weather events such as heat waves are becoming more frequent and intense. Populations can cope with elevated heat stress by evolving higher basal heat tolerance (evolutionary response) and/or stronger induced heat tolerance (plastic response). However, there is ongoing debate about whether basal and induced heat tolerance are negatively correlated and whether adaptive potential in heat tolerance is sufficient under ongoing climate warming. To evaluate the evolutionary potential of basal and induced heat tolerance, we performed experimental evolution on a temperate source population of the dung fly Sepsis punctum. Offspring of flies adapted to three thermal selection regimes (Hot, Cold and Reference) were subjected to acute heat stress after having been exposed to either a hot-acclimation or non-acclimation pretreatment. As different traits may respond differently to temperature stress, several physiological and life history traits were assessed. Condition dependence of the response was evaluated by exposing juveniles to different levels of developmental (food restriction/rearing density) stress. Heat knockdown times were highest, whereas acclimation effects were lowest in the Hot selection regime, indicating a negative association between basal and induced heat tolerance. However, survival, adult longevity, fecundity and fertility did not show such a pattern. Acclimation had positive effects in heat-shocked flies, but in the absence of heat stress hot-acclimated flies had reduced life spans relative to non-acclimated ones, thereby revealing a potential cost of acclimation. Moreover, body size positively affected heat tolerance and unstressed individuals were less prone to heat stress than stressed flies, offering support for energetic costs associated with heat tolerance. Overall, our results indicate that heat tolerance of temperate insects can evolve under rising temperatures, but this response could be limited by a negative relationship between basal and induced thermotolerance, and may involve some but not other fitness-related traits.

Mesostructured silica and aluminosilicate carriers for oxytetracycline delivery systems

Oxytetracycline delivery systems containing various MCM-type silica and aluminosilicate with different antibiotic content were developed in order to establish the influence of the support structural and textural properties and aluminum content on the drug release profile. The antibiotic molecules were loaded into the support mesochannels by incipient wetness impregnation method using a drug concentrated aqueous solution. The carriers and drug-loaded materials were investigated by small- and wide-angle XRD, FTIR spectroscopy, TEM and N2 adsorption-desorption isotherms. Faster release kinetics of oxytetracycline from uncalcined silica and aluminosilicate supports was observed, whereas higher drug content led to lower delivery rate. The presence of aluminum into the silica network also slowed down the release rate. The antimicrobial assays performed on Staphylococcus aureus clinical isolates showed that the oxytetracycline-loaded materials containing MCM-41-type mesoporous silica or aluminosilicate carriers inhibited the bacterial development.

Complex mitonuclear interactions and metabolic costs of mating in male seed beetles

The lack of evolutionary response to selection on mitochondrial genes through males predicts the evolution of nuclear genetic influence on male-specific mitochondrial function, for example by gene duplication and evolution of sex-specific expression of paralogs involved in metabolic pathways. Intergenomic epistasis may therefore be a prevalent feature of the genetic architecture of male-specific organismal function. Here, we assess the role of mitonuclear genetic variation for male metabolic phenotypes [metabolic rate and respiratory quotient (RQ)] associated with ejaculate renewal, in the seed beetle Callosobruchus maculatus, by assaying lines with crossed combinations of distinct mitochondrial haplotypes and nuclear lineages. We found a significant increase in metabolic rate following mating relative to virgin males. Moreover, processes associated with ejaculate renewal showed variation in metabolic rate that was affected by mitonuclear interactions. Mitochondrial haplotype influenced mating-related changes in RQ, but this pattern varied over time. Mitonuclear genotype and the energy spent during ejaculate production affected the weight of the ejaculate, but the strength of this effect varied across mitochondrial haplotypes showing that the genetic architecture of male-specific reproductive function is complex. Our findings unveil hitherto underappreciated metabolic costs of mating and ejaculate renewal, and provide the first empirical demonstration of mitonuclear epistasis on male reproductive metabolic processes.

[Diagnostics and therapy of chronic pain following hernia operation]

The frequency of chronic pain after hernia repair is currently much higher than the recurrence rate. For inguinal hernias it has been shown that mesh-based techniques are comparable to mesh-free techniques concerning chronic pain. Risk factors could be clearly identified for inguinal hernia repair and include open repair, meshes with small pores, mesh fixation with sutures or tacks, pre-existing pain and severe pain during the early postoperative period. The last two risk factors are also important for incisional hernias. For laparoscopic incisional hernia repair, the width (> 10 cm) of the gap seems to correlate with chronic pain. The diagnostic measures are restricted to the identification of a segmental problem in terms of nerve entrapment which can be blocked by local anesthesia or definite neurectomy. In some cases of chronic pain after inguinal hernia repair removal of the mesh will be advisable. After incisional hernia repair a segmental involvement is rarely seen. Localized pain may be induced by stay sutures which can be removed. Mesh removal is, however, a complex procedure especially after open repair resulting in hernia recurrence and therefore represents a salvage technique. The prophylaxis of chronic pain is therefore of utmost importance as is the identification of patients at risk which is now possible. These patients for example with inguinal hernias should be treated laparoscopically with an adequate technique including meshes with big pores and without fixation or fixation with glue only.

Experimental evolution for generalists and specialists reveals multivariate genetic constraints on thermal reaction norms

Theory predicts the emergence of generalists in variable environments and antagonistic pleiotropy to favour specialists in constant environments, but empirical data seldom support such generalist-specialist trade-offs. We selected for generalists and specialists in the dung fly Sepsis punctum (Diptera: Sepsidae) under conditions that we predicted would reveal antagonistic pleiotropy and multivariate trade-offs underlying thermal reaction norms for juvenile development. We performed replicated laboratory evolution using four treatments: adaptation at a hot (31 °C) or a cold (15 °C) temperature, or under regimes fluctuating between these temperatures, either within or between generations. After 20 generations, we assessed parental effects and genetic responses of thermal reaction norms for three correlated life-history traits: size at maturity, juvenile growth rate and juvenile survival. We find evidence for antagonistic pleiotropy for performance at hot and cold temperatures, and a temperature-mediated trade-off between juvenile survival and size at maturity, suggesting that trade-offs associated with environmental tolerance can arise via intensified evolutionary compromises between genetically correlated traits. However, despite this antagonistic pleiotropy, we found no support for the evolution of increased thermal tolerance breadth at the expense of reduced maximal performance, suggesting low genetic variance in the generalist-specialist dimension.

Laparoskopische Narbenhernienreparation

The rationale for laparoscopic repair of incisional hernias lies in the fact that any kind of incisional hernia is caused by an intrinsic defect of wound healing. This means that the abdominal wall needs to be reinforced with foreign nonresorbable material. During laparoscopic repair a nonresorbable mesh with the characteristic feature that its two surfaces are quite different is used to completely cover the original incision. One surface is designed to ensure stable incorporation into the abdominal wall and the other, to keep adhesions between the mesh and the bowel to a minimum. Experience reported since its first description in 1993 has clearly shown that the main advantage of the laparoscopic technique over conventional methods is that it involves an extremely low risk of mesh infection. The reported recurrence rates of 1-11% are mainly attributable to technical error and demonstrate that in this way too, the laparoscopic technique is at least as good as the open techniques. Up to now, no mesh-related complications in the form of fistula or mesh migration have been described. In conclusion, then, laparoscopic repair of ventral hernia is an important addition to the surgical armamentarium, which at least in our hands has almost completely replaced conventional techniques.