MHC-I alleles mediate clearance and antibody response to the zoonotic Lassa virus in Mastomys rodent reservoirs.

West African Mastomys rodents are the primary reservoir of the zoonotic Lassa virus (LASV). The virus causes haemorrhagic Lassa fever and considerable mortality in humans. To date, the role of Mastomys immunogenetics in resistance to, and persistence of, LASV infections is largely unknown. Here, we investigated the role of Major Histocompatibility Complex class I (MHC-I) on LASV infection status (i.e., active vs. cleared infection, determined via PCR and an immunofluorescence assay on IgG antibodies, respectively) in Mastomys natalensis and M. erythroleucus sampled within southwestern Nigeria. We identified more than 190 and 90 MHC-I alleles by Illumina high throughput-sequencing in M. natalensis and M. erythroleucus, respectively, with different MHC allele compositions and frequencies between LASV endemic and non-endemic sites. In M. natalensis, the MHC allele ManaMHC-I*006 was negatively associated with active infections (PCR-positive) and positively associated with cleared infections (IgG-positive) simultaneously, suggesting efficient immune responses that facilitate LASV clearance in animals carrying this allele. Contrarily, alleles ManaMHC-I*008 and ManaMHC-I*021 in M. natalensis, and MaerMHC-I*008 in M. erythroleucus, were positively associated with active infection, implying susceptibility. Alleles associated with susceptibility shared a glutamic acid at the positively selected codon 57, while ManaMHC-I*006 featured an arginine. There was no link between number of MHC alleles per Mastomys individual and LASV prevalence. Thus, specific alleles, but not MHC diversity per se, seem to mediate antibody responses to viremia. We conclude that co-evolution with LASV likely shaped the MHC-I diversity of the main LASV reservoirs in southwestern Nigeria, and that information on reservoir immunogenetics may hold insights into transmission dynamics and zoonotic spillover risks.

Immunogenetic-pathogen networks shrink in Tome's spiny rat, a generalist rodent inhabiting disturbed landscapes.

Anthropogenic disturbance may increase the emergence of zoonoses. Especially generalists that cope with disturbance and live in close contact with humans and livestock may become reservoirs of zoonotic pathogens. Yet, whether anthropogenic disturbance modifies host-pathogen co-evolutionary relationships in generalists is unknown. We assessed pathogen diversity, neutral genome-wide diversity (SNPs) and adaptive MHC class II diversity in a rodent generalist inhabiting three lowland rainforest landscapes with varying anthropogenic disturbance, and determined which MHC alleles co-occurred more frequently with 13 gastrointestinal nematodes, blood trypanosomes, and four viruses. Pathogen-specific selection pressures varied between landscapes. Genome-wide diversity declined with the degree of disturbance, while MHC diversity was only reduced in the most disturbed landscape. Furthermore, pristine forest landscapes had more functional important MHC-pathogen associations when compared to disturbed forests. We show co-evolutionary links between host and pathogens impoverished in human-disturbed landscapes. This underscores that parasite-mediated selection might change even in generalist species following human disturbance which in turn may facilitate host switching and the emergence of zoonoses.

Immunogenetics, sylvatic plague and its vectors: insights from the pathogen reservoir Mastomys natalensis in Tanzania.

Yersinia pestis is a historically important vector-borne pathogen causing plague in humans and other mammals. Contemporary zoonotic infections with Y. pestis still occur in sub-Saharan Africa, including Tanzania and Madagascar, but receive relatively little attention. Thus, the role of wildlife reservoirs in maintaining sylvatic plague and spillover risks to humans is largely unknown. The multimammate rodent Mastomys natalensis is the most abundant and widespread rodent in peri-domestic areas in Tanzania, where it plays a major role as a Y. pestis reservoir in endemic foci. Yet, how M. natalensis' immunogenetics contributes to the maintenance of plague has not been investigated to date. Here, we surveyed wild M. natalensis for Y. pestis vectors, i.e., fleas, and tested for the presence of antibodies against Y. pestis using enzyme-linked immunosorbent assays (ELISA) in areas known to be endemic or without previous records of Y. pestis in Tanzania. We characterized the allelic and functional (i.e., supertype) diversity of the major histocompatibility complex (MHC class II) of M. natalensis and investigated links to Y. pestis vectors and infections. We detected antibodies against Y. pestis in rodents inhabiting both endemic areas and areas considered non-endemic. Of the 111 nucleotide MHC alleles, only DRB*016 was associated with an increased infestation with the flea Xenopsylla. Surprisingly, we found no link between MHC alleles or supertypes and antibodies of Y. pestis. Our findings hint, however, at local adaptations towards Y. pestis vectors, an observation that more exhaustive sampling could unwind in the future.

Climate change drives loss of bacterial gut mutualists at the expense of host survival in wild meerkats.

Climate change and climate-driven increases in infectious disease threaten wildlife populations globally. Gut microbial responses are predicted to either buffer or exacerbate the negative impacts of these twin pressures on host populations. However, examples that document how gut microbial communities respond to long-term shifts in climate and associated disease risk, and the consequences for host survival, are rare. Over the past two decades, wild meerkats inhabiting the Kalahari have experienced rapidly rising temperatures, which is linked to the spread of tuberculosis (TB). We show that over the same period, the faecal microbiota of this population has become enriched in Bacteroidia and impoverished in lactic acid bacteria (LAB), a group of bacteria including Lactococcus and Lactobacillus that are considered gut mutualists. These shifts occurred within individuals yet were compounded over generations, and were better explained by mean maximum temperatures than mean rainfall over the previous year. Enriched Bacteroidia were additionally associated with TB exposure and disease, the dry season and poorer body condition, factors that were all directly linked to reduced future survival. Lastly, abundances of LAB taxa were independently and positively linked to future survival, while enriched taxa did not predict survival. Together, these results point towards extreme temperatures driving an expansion of a disease-associated pathobiome and loss of beneficial taxa. Our study provides the first evidence from a longitudinally sampled population that climate change is restructuring wildlife gut microbiota, and that these changes may amplify the negative impacts of climate change through the loss of gut mutualists. While the plastic response of host-associated microbiotas is key for host adaptation under normal environmental fluctuations, extreme temperature increases might lead to a breakdown of coevolved host-mutualist relationships.

MHC class II genes mediate susceptibility and resistance to coronavirus infections in bats.

Understanding the immunogenetic basis of coronavirus (CoV) susceptibility in major pathogen reservoirs, such as bats, is central to inferring their zoonotic potential. Members of the cryptic Hipposideros bat species complex differ in CoV susceptibility, but the underlying mechanisms remain unclear. The genes of the major histocompatibility complex (MHC) are the best understood genetic basis of pathogen resistance, and differences in MHC diversity are one possible reason for asymmetrical infection patterns among closely related species. Here, we aimed to link asymmetries in observed CoV (CoV-229E, CoV-2B and CoV-2Bbasal) susceptibility to immunogenetic differences amongst four Hipposideros bat species. From the 2072 bats assigned to their respective species using the mtDNA cytochrome b gene, members of the most numerous and ubiquitous species, Hipposideros caffer D, were most infected with CoV-229E and SARS-related CoV-2B. Using a subset of 569 bats, we determined that much of the existent allelic and functional (i.e. supertype) MHC DRB class II diversity originated from common ancestry. One MHC supertype shared amongst all species, ST12, was consistently linked to susceptibility with CoV-229E, which is closely related to the common cold agent HCoV-229E, and infected bats and those carrying ST12 had a lower body condition. The same MHC supertype was connected to resistance to CoV-2B, and bats with ST12 were less likely be co-infected with CoV-229E and CoV-2B. Our work suggests a role of immunogenetics in determining CoV susceptibility in bats. We advocate for the preservation of functional genetic and species diversity in reservoirs as a means of mitigating the risk of disease spillover.

Co-infections mask pathogen-specific associations with the gut microbiota in wild voles.

Research Highlight: Brila, I., Lavirinienko, A., Tukalenko, E., Kallio, E. R., Mappes, T. & Watts, P. C. (2022). Idiosyncratic effects of coinfection on the association between systemic pathogens and the gut microbiota of a wild rodent, the bank vole (Myodes glareolus). Journal of Animal Ecology, https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.13869. Interactions between pathogens and host-associated microbial communities can influence host fitness, disease progression and pathogen emergence. The vast majority of studies characterize interactions between single pathogens and bacterial commensals, yet co-infections with multiple pathogens are the norm in nature. In their paper on pathogen-microbiome interactions, Brila et al. (2022) examine how co-infections with four systemic pathogens associate with the gut microbiota in wild bank voles. Building on a series of tests, the authors show that excluding co-infection information from statistical models masks pathogen-specific patterns and confounds interpretations. This paper advances on previous studies by generating surveillance data on a phylogenetically diverse suite of vole pathogens to address the question as to whether pathogens exhibit unique or universal associations with gut commensals. They report that even bacterial pathogens with similar transmission ecology have divergent associations with gut microbes, and highlight that a mechanistic understanding of host-pathogen interactions is necessary for decoding the diverse consequences for gut microbial communities.

Disentangling direct from indirect effects of habitat disturbance on multiple components of biodiversity.

Human habitat disturbance affects both species diversity and intraspecific genetic diversity, leading to correlations between these two components of biodiversity (termed species-genetic diversity correlation, SGDC). However, whether SGDC predictions extend to host-associated communities, such as the intestinal parasite and gut microbial diversity, remains largely unexplored. Additionally, the role of dominant generalist species is often neglected despite their importance in shaping the environment experienced by other members of the ecological community, and their role as source, reservoir and vector of zoonotic diseases. New analytical approaches (e.g. structural equation modelling, SEM) can be used to assess SGDC relationships and distinguish among direct and indirect effects of habitat characteristics and disturbance on the various components of biodiversity. With six concrete and biologically sound models in mind, we collected habitat characteristics of 22 study sites from four distinct landscapes located in central Panama. Each landscape differed in the degree of human disturbance and fragmentation measured by several quantitative variables, such as canopy cover, canopy height and understorey density. In terms of biodiversity, we estimated on the one hand, (a) small mammal species diversity, and, on the other hand, (b) genome-wide diversity, (c) intestinal parasite diversity and (d) gut microbial heterogeneity of the most dominant generalist species (Tome's spiny rat, Proechimys semispinosus). We used SEMs to assess the links between habitat characteristics and biological diversity measures. The best supported SEM suggested that habitat characteristics directly and positively affect the richness of small mammals, the genetic diversity of P. semispinosus and its gut microbial heterogeneity. Habitat characteristics did not, however, directly impact intestinal parasite diversity. We also detected indirect, positive effects of habitat characteristics on both host-associated assemblages via small mammal richness. For microbes, this is likely linked to cross species transmission, particularly in shared and/or anthropogenically altered habitats, whereas host diversity mitigates parasite infections. The SEM revealed an additional indirect but negative effect on intestinal parasite diversity via host genetic diversity. Our study showcases that habitat alterations not only affect species diversity and host genetic diversity in parallel, but also species diversity of host-associated assemblages. The impacts from human disturbance are therefore expected to ripple through entire ecosystems with far reaching effects felt even by generalist species.

Las perturbaciones antropogénicas sobre los hábitats naturales pueden afectar tanto a la diversidad de las especies como a la diversidad genética intraespecífica, dando lugar a correlaciones entre estos dos elementos de la biodiversidad (denominados correlación de la diversidad genética de las especies, SGDC por sus siglas en inglés). Sin embargo, todavía queda sin explorar si las predicciones de la SGDC afectan a las comunidades de parásitos y microorganismos intestinales asociadas al hospedador. Adicionalmente, el rol que juegan las especies generalistas, especialmente aquéllas dominantes, suele ser descuidado, a pesar de la importancia de control que ejercen sobre la estructura de la comunidad, y su rol como fuente, reservorio y vector de enfermedades zoonóticas. Para poder evaluar las relaciones de SGDC y distinguir entre los efectos directos e indirectos que tienen las características del hábitat y las perturbaciones sobre los distintos componentes de la biodiversidad, se pueden utilizar nuevos enfoques analíticos como por ejemplo los modelos de ecuaciones estructurales (SEM, por sus siglas en inglés). Considerando seis modelos específicos y biológicamente sólidos, recopilamos las características del hábitat de 22 sitios ubicados en cuatro paisajes distintos situados en el centro de Panamá. Cada paisaje difería en el grado de perturbación antropogénica y fragmentación, medido por diferentes variables cuantitativas, como la cobertura del dosel, la altura del dosel y la densidad del sotobosque. En términos de biodiversidad, por un lado estimamos (1) la diversidad de especies de pequeños mamíferos y, por otro lado (2) la diversidad del genoma completo, (3) la diversidad de parásitos intestinales, y (4) la heterogeneidad de las comunidades microbianas del intestino de la especie generalista más dominante, la rata espinosa de Tomes Proechimys semispinosus. Para evaluar los vínculos entre las características del hábitat y las medidas de diversidad biológica se utilizó el modelado SEM. El SEM mejor apoyado sugirió que las características del hábitat afectan directa y positivamente a la abundancia de pequeños mamíferos, a la diversidad genética de P. semispinosus y a la heterogeneidad microbiana intestinal. Sin embargo, se observó que las características del hábitat no tienen un efecto directo en la diversidad de parásitos intestinales. Aparte de estos efectos directos, detectamos efectos indirectos y positivos de las características del hábitat en ambos conjuntos asociados al hospedador (diversidad de parásitos y microorganismos intestinales) a través de la abundancia de pequeños mamíferos. En el caso de las comunidades microbianas, esto está probablemente relacionado con la transmisión interespecífica, especialmente en hábitats compartidos y/o antropogénicamente alterados; mientras que la diversidad de hospedadores mitiga las infecciones de parásitos. El SEM reveló un efecto indirecto adicional pero negativo sobre la diversidad de parásitos intestinales a través de la diversidad genética de los hospedadores. Nuestro estudio muestra que los patrones de SGDC se filtran a través de las varias capas de diversidad biológica, añadiendo los ensamblajes asociados al hospedador como componentes biológicos afectados por las alteraciones del hábitat.

Gut microbiota individuality is contingent on temporal scale and age in wild meerkats.

Inter-individual differences in gut microbiota composition are hypothesized to generate variation in host fitness-a premise for the evolution of host-gut microbe symbioses. However, recent evidence suggests that gut microbial communities are highly dynamic, challenging the notion that individuals harbour unique gut microbial phenotypes. Leveraging a long-term dataset of wild meerkats, we reconcile these concepts by demonstrating that the relative importance of identity for shaping gut microbiota phenotypes depends on the temporal scale. Across meerkat lifespan, year-to-year variation overshadowed the effects of identity and social group in predicting gut microbiota composition, with identity explaining on average less than 2% of variation. However, identity was the strongest predictor of microbial phenotypes over short sampling intervals (less than two months), predicting on average 20% of variation. The effect of identity was also dependent on meerkat age, with the gut microbiota becoming more individualized and stable as meerkats aged. Nevertheless, while the predictive power of identity was negligible after two months, gut microbiota composition remained weakly individualized compared to that of other meerkats for up to 1 year. These findings illuminate the degree to which individualized gut microbial signatures can be expected, with important implications for the time frames over which gut microbial phenotypes may mediate host physiology, behaviour and fitness in natural populations.

A framework for testing the impact of co-infections on host gut microbiomes.

Parasitic infections disturb gut microbial communities beyond their natural range of variation, possibly leading to dysbiosis. Yet it remains underappreciated that most infections are accompanied by one or more co-infections and their collective impact is largely unexplored. Here we developed a framework illustrating changes to the host gut microbiome following single infections, and build on it by describing the neutral, synergistic or antagonistic impacts on microbial α- and ß-diversity expected from co-infections. We tested the framework on microbiome data from a non-human primate population co-infected with helminths and Adenovirus, and matched patterns reported in published studies to the introduced framework. In this case study, α-diversity of co-infected Malagasy mouse lemurs (Microcebus griseorufus) did not differ in comparison with that of singly infected or uninfected individuals, even though community composition captured with ß-diversity metrices changed significantly. Explicitly, we record stochastic changes in dispersion, a sign of dysbiosis, following the Anna-Karenina principle rather than deterministic shifts in the microbial gut community. From the literature review and our case study, neutral and synergistic impacts emerged as common outcomes from co-infections, wherein both shifts and dispersion of microbial communities following co-infections were often more severe than after a single infection alone, but microbial α-diversity was not universally altered. Important functions of the microbiome may also suffer from such heavily altered, though no less species-rich microbial community. Lastly, we pose the hypothesis that the reshuffling of host-associated microbial communities due to the impact of various, often coinciding parasitic infections may become a source of novel or zoonotic diseases.

Two decades of tuberculosis surveillance reveal disease spread, high levels of exposure and mortality and marked variation in disease progression in wild meerkats.

Infections with tuberculosis (TB)-causing agents of the Mycobacterium tuberculosis complex threaten human, livestock and wildlife health globally due to the high capacity to cross trans-species boundaries. Tuberculosis is a cryptic disease characterized by prolonged, sometimes lifelong subclinical infections, complicating disease monitoring. Consequently, our understanding of infection risk, disease progression, and mortality across species affected by TB remains limited. The TB agent Mycobacterium suricattae was first recorded in the late 1990s in a wild population of meerkats inhabiting the Kalahari in South Africa and has since spread considerably, becoming a common cause of meerkat mortality. This offers an opportunity to document the epidemiology of naturally spreading TB in a wild population. Here, we synthesize more than 25 years' worth of TB reporting and social interaction data across 3420 individuals to track disease spread, and quantify rates of TB social exposure, progression, and mortality. We found that most meerkats had been exposed to the pathogen within eight years of first detection in the study area, with exposure reaching up to 95% of the population. Approximately one quarter of exposed individuals progressed to clinical TB stages, followed by physical deterioration and death within a few months. Since emergence, 11.6% of deaths were attributed to TB, although the true toll of TB-related mortality is likely higher. Lastly, we observed marked variation in disease progression among individuals, suggesting inter-individual differences in both TB susceptibility and resistance. Our results highlight that TB prevalence and mortality could be higher than previously reported, particularly in species or populations with complex social group dynamics. Long-term studies, such as the present one, allow us to assess temporal variation in disease prevalence and progression and quantify exposure, which is rarely measured in wildlife. Long-term studies are highly valuable tools to explore disease emergence and ecology and study host-pathogen co-evolutionary dynamics in general, and its impact on social mammals.

Interaction between MHC diversity and constitution, gut microbiota and Astrovirus infections in a neotropical bat.

Astroviruses (AstVs) infect numerous mammalian species including reservoirs such as bats. Peptides encoded by the genes of the highly polymorphic Major Histocompatibility Complex (MHC) form the first line of host defence against pathogens. Aside from direct involvement in mounting adaptive immune responses, MHC class II genes are hypothesized to regulate gut commensal diversity and shape the production of immune-modulatory substances by microbes, indirectly affecting host susceptibility. Despite initial empirical evidence for the link between host MHC and the microbiota, associations among these factors remain largely unknown. To fill this gap, we examined MHC allelic diversity and constitution, the gut bacterial community and abundance pattern of a wild population of a neotropical bat (Artibeus jamaicensis) challenged by AstV infections. First, we show an age-dependent relationship between the host MHC class II diversity and constitution and the gut microbiota in AstV-uninfected bats. Crucially, these associations changed in AstV-infected bats. Additionally, we identify changes in the abundance of specific bacterial taxa linked to the presence of certain MHC supertypes and AstV infection. We suggest changes in the microbiota to be either a result of AstV infection or the MHC-mediated modulation of microbial communities. The latter could subsequently affect microbe-mediated immunity and resistance against AstV infection. Our results emphasize that the reciprocal nature of host immune genetics, gut microbial diversity and pathogen infection require attention, which are particularly important given their repercussions for disease susceptibility and severity in wild animal populations with a history of zoonotic spillover and frequent human contact.

Left ventricular mechanics and cardiovascular outcomes in non-compaction phenotype.

AIMS: This study aims at understanding left ventricular (LV) mechanics of non-compaction (LVNC) phenotype using echocardiographic strain analysis and at assessing the association of functional parameters with cardiovascular (CV) outcomes. METHODS AND RESULTS: Longitudinal (GLS) and circumferential strain (GCS) as well as rotation of the LV were analyzed in 55 LVNC patients and 55 matched controls. Cardiovascular outcomes were documented for a median follow-up duration of 6 years. GLS and GCS were impaired in LVNC. Similary, regional longitudinal and circumferential strain as well as twist were reduced. CV events occurred in 28 LVNC patients. Apical peak circumferential strain (APCS), peak systolic rotation of apical segments (APSR), and twist were strongly associated with events. This was independent of and incremental to LVEF and non-compacted to compacted myocardial thickness ratio (NC:C ratio). The association of twist with events was also independent of and slightly superior to GLS. CONCLUSIONS: GLS, GCS, regional strain, and twist were impaired in LVNC. APCS, APSR, and twist exhibited strong association with CV events independent of and incremental to LVEF and NC:C ratio, and in case of twist even GLS. Thus, STE-derived parameters may complement the echocardiographic assessment of LVNC patients in clinical routine.

Noise pollution on coral reefs? - A yet underestimated threat to coral reef communities.

Noise pollution is an anthropogenic stressor that is increasingly recognized for its negative impact on the physiology, behavior and fitness of marine organisms. Driven by the recent expansion of maritime shipping, artisanal fishing and tourism (e.g., motorboats used for recreational purpose), underwater noise increased greatly on coral reefs. In this review, we first provide an overview on how reef organisms sense and use sound. Thereafter we review the current knowledge on how underwater noise affects different reef organisms. Although the majority of available examples are limited to few fish species, we emphasize how the impact of noise differs based on an organisms' acoustic sensitivity, mobility and developmental stage, as well as between noise type, source and duration. Finally, we highlight measures available to governments, the shipping industry and individual users and provide directions for polices and research aimed to manage this global issue of noise emission on coral reefs.

Synthesis and Structure-Affinity Relationship of Small Molecules for Imaging Human CD80 by Positron Emission Tomography.

The costimulatory molecule CD80 is an early marker for immune activation. It is upregulated on activated antigen-presenting cells. We aimed at developing a tracer for imaging CD80 by positron emission tomography (PET). Novel CD80 ligands were synthesized and tested by SPR for affinity to human CD80 (hCD80) and displacement of endogenous ligands. Several compounds bound with one-digit nanomolar affinity to hCD80 and displaced CTLA-4 and CD28 at nanomolar concentrations. A structure-affinity relationship study revealed relevant moieties for strong affinity to hCD80 and positions for further modifications. Lead compound MT107 (7f) was radiolabeled with carbon-11. In vitro, [11C]MT107 showed specific binding to hCD80-positive tissue and high plasma protein binding. In vivo, [11C]MT107 accumulated in liver, gall bladder, and intestines but only scarcely in hCD80-positive xenografts. The unfavorable in vivo performance may result from high plasma protein binding and extensive biliary excretion.

Rapid Divergence of Predator Functional Traits Affects Prey Composition in Aquatic Communities.

Identifying traits that underlie variation in individual performance of consumers (i.e., trait utility) can help reveal the ecological causes of population divergence and the subsequent consequences for species interactions and community structure. Here, we document a case of rapid divergence (over the past 100 generations, or ∼150 years) in foraging traits and feeding efficiency between a lake and stream population pair of threespine stickleback. Building on predictions from functional trait models of fish feeding, we analyzed foraging experiments with a Bayesian path analysis and elucidated the traits explaining variation in foraging performance and the species composition of ingested prey. Despite extensive previous research on the divergence of foraging traits among populations and ecotypes of stickleback, our results provide novel experimental evidence of trait utility for jaw protrusion, gill raker length, and gill raker spacing when foraging on a natural zooplankton assemblage. Furthermore, we discuss how these traits might contribute to the differential effects of lake and stream stickleback on their prey communities, observed in both laboratory and mesocosm conditions. More generally, our results illustrate how the rapid divergence of functional foraging traits of consumers can impact the biomass, species composition, and trophic structure of prey communities.

Transgenerational selection driven by divergent ecological impacts of hybridizing lineages.

Dynamic interactions between ecological conditions and the phenotypic composition of populations likely play an important role in evolution, but the direction and strength of these feedbacks remain difficult to characterize. We investigated these dynamics across two generations of threespine sticklebacks from two evolutionary lineages undergoing secondary contact and hybridization. Independently manipulating the density and lineage of adults in experimental mesocosms led to contrasting ecosystem conditions with strong effects on total survival in a subsequent generation of juveniles. Ecosystem modifications by adults also varied the strength of selection on competing hybrid and non-hybrid juveniles. This variation in selection indicated (1) a negative eco-evolutionary feedback driven by lineage-specific resource depletion and dependence and (2) a large performance advantage of hybrid juveniles in depleted environments. This work illustrates the importance of interactions between phenotype, population density and the environment in shaping selection and evolutionary trajectories, especially in the context of range expansion with secondary contact and hybridization.

Successful therapy for a patient with an infected ascending aortic graft and sternal osteomyelitis without graft removal.

OBJECTIVE: Following open-heart surgery, sternal osteomyelitis or infection of the graft may be a serious complication with high mortality rates. The recommended treatment of an infected graft is its explantation. Because of the poor performance status of the patient, this may not always be an option. We report a successful treatment concept without removal of the infected graft. METHODS: The infected ascending aortic graft and the remaining sternum of a critically ill 60-year-old man were covered with a bilateral pectoralis muscle flap. RESULTS: Postoperatively, the laboratory test values normalized and the patient was discharged 1 month after the intervention. One year after surgery, the patient was in good condition and the examination showed no signs of infection. CONCLUSION: The thus demonstrated treatment concept with insertion of well-vascularized tissues in combination with a specific antibiotic regime in our hands proved to be an additional option for the successful management of life-threatening infections of a sternal osteomyelitis in combination of an infected aortic graft.

Posterior auricular perichondrial cutaneous graft combined with cartilage strip in nostril reconstruction.

OBJECTIVE: Reconstruction of alar structures of the nose remains difficult. The result has to be not only functional but also aesthetic. Different solutions to reconstruct alar defects are feasible. A good result that meets the specific demands on stability, aesthetics, and stable architecture without shrinkage of the area is not easily achieved. METHOD: A perichondrial cutaneous graft (PCCG), a graft consisting of a perichondral layer, fatty tissue, and skin that is harvested retroauriculary, is combined with an attached cartilage strip. CASE RESULT: A 72-year-old patient suffering from basal cell carcinoma of the ala of the nose underwent the reconstructive procedure with a good result in 1 year in terms of stability, color match, and graft take. CONCLUSION: First, a strip of cartilage had been included in a PCCG where tumor resection required sacrifice of more than 50% of the alar rim. The case shows that one can consider a cartilage strip-enhanced PCCG graft to reconstruct alar defects.

Perforator-sparing abdominoplasty technique in the presence of bilateral subcostal scars after gastric bypass.

BACKGROUND: The number of patients after gastric bypass being referred to plastic surgery units for secondary plastic surgery procedures is increasing. The characteristic abdominal deformity includes a draping apron of panniculus, occasionally associated with previous transverse surgical scars in the upper abdomen. Often a limited abdominoplasty of the low transverse type with limited undermining only up to the level of the umbilicus is performed in order not to compromise blood supply in the zone between the old transverse and the new transverse scar. METHOD: We propose a new, modified and safe surgical technique to perform a complete abdominoplasty with wide undermining up to the xiphoid process in patients with preexisting transverse subcostal scars after gastric bypass surgery, by selectively dissecting and preserving one to three periumbilical abdominal wall perforator vessels to secure flap blood supply. Vessel tunnelling through the rectus sheath and muscle and ligation of the cephalad branch of the perforator provide sufficient flap mobility without perforator tension or traction. Flap undermining is performed around these perforator vessels. To match dissected flap perforators with blood-flow, we performed post-operative color-flow duplex scanning. RESULTS: We treated two patients according to this new technique. In both cases the postoperative course was uneventful and a good aesthetic result was achieved. CONCLUSION: We conclude from our experience that with this perforator-sparing abdominoplasty technique, safe and complete abdominoplasty can be performed with no additional risk of complications and that a good cosmetic result can be achieved in patients after open gastric bypass surgery.