Femoral deficiency reconstruction using a hydroxyapatite-coated locked modular stem. A series of 43 total hip revisions

SummaryIntroductionWe report a continuous prospective series of patients operated on for total hip prosthesis femoral component loosening involving a bone defect. Reconstruction was performed using a hydroxyapatite-coated locked modular stem. The study's objective was to assess medium term clinical and X-ray results obtained with this original concept.Materials and methodsThe patients included received a REEF® (DePuy) femoral implant for aseptic loosening or loosening associated with a periprosthetic fracture. Implantation was systematically accompanied by an extended trochanteric osteotomy (ETO). Patients were followed up prospectively by clinical and X-ray examination. Their loosening was graded at inclusion according to Vives’ classification as revised by SOFCOT in 1999. Analysis focused on actuarial implant survivorship, dislocation and the bone/implant interface.ResultsForty-three hips were included: mean follow-up was 58.2 months (12–92) and mean age at surgery was 72.4 years (37–94). The main indications were severe bone loss rated grade III (n=15) or IV (n=16) according to the SOFCOT classification. There was one long-term failure, involving implant fracture secondary to nonunion of the femoral shaft. Mean Postel and Merle d’Aubigné (PMA) clinical assessment score increased from six preoperatively to 14.5 at end of follow-up. X-ray analysis found no stem migration by end of follow-up. There was consistent consolidation of the ETO around the stem, except in one case of stem fracture which evolved into tight nonunion. In terms of metaphyseal integration, five patients showed radiolucency without evolution over follow-up, and eight had severe calcar cortical atrophy at end of follow-up. Mean 5-year actuarial survivorship was 97.7±2.3%, with a 2% incidence of dislocation.DiscussionThe complications rate was low, and results were comparable with those reported in the literature. The study confirmed the interest of the extended trochanteric osteotomy exposure and the effectiveness of the hydroxyapatite-coated interlocked modular stem concept in the treatment of hip prosthesis loosening with femoral bone loss (involving or not the cortex). On analysis, the one case of failure does not proscribe the surgical technique employed. Implant osseointegration was difficult to analyze. The extent of the surgical approach and of its corresponding sequels, combined with the complexity of adjusting the implant, however, restrict this surgical option indications to level III and IV cases of femoral loosening.Level of evidence: level IV; therapeutic study

Implication of coronin 7 in body weight regulation in humans, mice and flies

Background: Obesity is a growing global concern with strong associations with cardiovascular disease, cancer and type-2 diabetes. Although various genome-wide association studies have identified more than 40 genes associated with obesity, these genes cannot fully explain the heritability of obesity, suggesting there may be other contributing factors, including epigenetic effects. Results: We performed genome wide DNA methylation profiling comparing normal-weight and obese 9-13 year old children to investigate possible epigenetic changes correlated with obesity. Of note, obese children had significantly lower methylation levels at a CpG site located near coronin 7 (CORO7), which encodes a tryptophan-aspartic acid dipeptide (WD)-repeat containing protein most likely involved in Golgi complex morphology and function. Anatomical profiling of coronin 7 (Coro7) mRNA expression in mice revealed that it is highly expressed in appetite and energy balance regulating regions, including the hypothalamus, striatum and locus coeruleus, the main noradrenergic brain site. Interestingly, we found that food deprivation in mice downregulates hypothalamic Coro7 mRNA levels, and injecting ethanol, an appetite stimulant, increased the number of Coro7 expressing cells in the locus coeruleus. Finally, by employing the genetically-tractable Drosophila melanogaster model we were able to demonstrate an evolutionarily conserved metabolic function for the CORO7 homologue pod1. Knocking down the pod1 in the Drosophila adult nervous system increased their resistance to starvation. Furthermore, feeding flies a high-calorie diet significantly increased pod1 expression. Conclusion: We conclude that coronin 7 is involved in the regulation of energy homeostasis and this role stems, to some degree, from the effect on feeding for calories and reward

Dual mobility cup reduces dislocation rate after arthroplasty for femoral neck fracture

<p>Abstract</p> <p>Background</p> <p>Hip dislocation after arthroplasty for femoral neck fractures remains a serious complication. The aim of our study was to investigate the dislocation rate in acute femoral neck fracture patients operated with a posterior approach with cemented conventional or dual articulation acetabular components.</p> <p>Methods</p> <p>We compared the dislocation rate in 56 consecutive patients operated with conventional (single mobility) cemented acetabular components to that in 42 consecutive patients operated with dual articulation acetabular components. All the patients were operated via posterior approach and were followed up to one year postoperatively.</p> <p>Results</p> <p>There were 8 dislocations in the 56 patients having conventional components as compared to no dislocations in those 42 having dual articulation components (p = 0.01). The groups were similar with respect to age and gender distribution.</p> <p>Conclusions</p> <p>We conclude that the use of a cemented dual articulation acetabular component significantly reduces the dislocation rates in femoral neck fracture patients operated via posterior approach.</p

Astrocytes and oligodendrocytes in the thalamus jointly maintain synaptic activity by supplying metabolites

Thalamic astrocytes and oligodendrocytes are coupled via gap junctions and form panglial networks. Here, we show that these networks have a key role in energy supply of neurons. Filling an astrocyte or an oligodendrocyte in acute slices with glucose or lactate is sufficient to rescue the decline of stimulation-induced field post-synaptic potential (fPSP) amplitudes during extracellular glucose deprivation (EGD). In mice lacking oligodendroglial coupling, loading an astrocyte with glucose does not rescue the EGD-mediated loss of fPSPs. Monocarboxylate and glucose transporters are required for rescuing synaptic activity during EGD. In mice deficient in astrocyte coupling, filling of an oligodendrocyte with glucose does not rescue fPSPs during EGD. Our results demonstrate that, in the thalamus, astrocytes and oligodendrocytes are jointly engaged in delivering energy substrates for sustaining neuronal activity and suggest that oligodendrocytes exert their effect mainly by assisting astrocytes in metabolite transfer to the postsynapse

Compared to conventional, ecological intensive management promotes beneficial proteolytic soil microbial communities for agro-ecosystem functioning under climate change-induced rain regimes

Projected climate change and rainfall variability will affect soil microbial communities, biogeochemical cycling and agriculture. Nitrogen (N) is the most limiting nutrient in agroecosystems and its cycling and availability is highly dependent on microbial driven processes. In agroecosystems, hydrolysis of organic nitrogen (N) is an important step in controlling soil N availability. We analyzed the effect of management (ecological intensive vs. conventional intensive) on N-cycling processes and involved microbial communities under climate change-induced rain regimes. Terrestrial model ecosystems originating from agroecosystems across Europe were subjected to four different rain regimes for 263 days. Using structural equation modelling we identified direct impacts of rain regimes on N-cycling processes, whereas N-related microbial communities were more resistant. In addition to rain regimes, management indirectly affected N-cycling processes via modifications of N-related microbial community composition. Ecological intensive management promoted a beneficial N-related microbial community composition involved in N-cycling processes under climate change-induced rain regimes. Exploratory analyses identified phosphorus-associated litter properties as possible drivers for the observed management effects on N-related microbial community composition. This work provides novel insights into mechanisms controlling agro-ecosystem functioning under climate change

Metabolic flexibility as a major predictor of spatial distribution in microbial communities

A better understand the ecology of microbes and their role in the global ecosystem could be achieved if traditional ecological theories can be applied to microbes. In ecology organisms are defined as specialists or generalists according to the breadth of their niche. Spatial distribution is often used as a proxy measure of niche breadth; generalists have broad niches and a wide spatial distribution and specialists a narrow niche and spatial distribution. Previous studies suggest that microbial distribution patterns are contrary to this idea; a microbial generalist genus (Desulfobulbus) has a limited spatial distribution while a specialist genus (Methanosaeta) has a cosmopolitan distribution. Therefore, we hypothesise that this counter-intuitive distribution within generalist and specialist microbial genera is a common microbial characteristic. Using molecular fingerprinting the distribution of four microbial genera, two generalists, Desulfobulbus and the methanogenic archaea Methanosarcina, and two specialists, Methanosaeta and the sulfate-reducing bacteria Desulfobacter were analysed in sediment samples from along a UK estuary. Detected genotypes of both generalist genera showed a distinct spatial distribution, significantly correlated with geographic distance between sites. Genotypes of both specialist genera showed no significant differential spatial distribution. These data support the hypothesis that the spatial distribution of specialist and generalist microbes does not match that seen with specialist and generalist large organisms. It may be that generalist microbes, while having a wider potential niche, are constrained, possibly by intrageneric competition, to exploit only a small part of that potential niche while specialists, with far fewer constraints to their niche, are more capable of filling their potential niche more effectively, perhaps by avoiding intrageneric competition. We suggest that these counter-intuitive distribution patterns may be a common feature of microbes in general and represent a distinct microbial principle in ecology, which is a real challenge if we are to develop a truly inclusive ecology

Remotely Sensed Canopy Nitrogen Correlates With Nitrous Oxide Emissions in a Lowland Tropical Rainforest

Tropical forests exhibit significant heterogeneity in plant functional and chemical traits that may contribute to spatial patterns of key soil biogeochemical processes, such as carbon storage and greenhouse gas emissions. Although tropical forests are the largest ecosystem source of nitrous oxide (N2O), drivers of spatial patterns within forests are poorly resolved. Here, we show that local variation in canopy foliar N, mapped by remote‐sensing image spectroscopy, correlates with patterns of soil N2O emission from a lowland tropical rainforest. We identified ten 0.25 ha plots (assemblages of 40–70 individual trees) in which average remotely‐sensed canopy N fell above or below the regional mean. The plots were located on a single minimally‐dissected terrace (km2) where soil type, vegetation structure and climatic conditions were relatively constant. We measured N2O fluxes monthly for 1 yr and found that high canopy N species assemblages had on average three‐fold higher total mean N2O fluxes than nearby lower canopy N areas. These differences are consistent with strong differences in litter stoichiometry, nitrification rates and soil nitrate concentrations. Canopy N status was also associated with microbial community characteristics: lower canopy N plots had two‐fold greater soil fungal to bacterial ratios and a significantly lower abundance of ammonia‐oxidizing archaea, although genes associated with denitrification (nirS, nirK, nosZ) showed no relationship with N2O flux. Overall, landscape emissions from this ecosystem are at the lowest end of the spectrum reported for tropical forests, consist with multiple metrics indicating that these highly productive forests retain N tightly and have low plant‐available losses. These data point to connections between canopy and soil processes that have largely been overlooked as a driver of denitrification. Defining relationships between remotely‐sensed plant traits and soil processes offers the chance to map these processes at large scales, potentially increasing our ability to predict N2O emissions in heterogeneous landscapes

Polymer versus phosphine stabilized Rh nanoparticles as components of supported catalysts : implication in the hydrogenation of cyclohexene model molecule

The solution synthesis of rhodium nanoparticles (Rh NPs) was achieved from the organometallic complex [Rh(η³-C₃H₅)₃] under mild reaction conditions in the presence of a polymer (PVP), a monophosphine (PPh₃) and a diphosphine (dppb) as a stabilizer, leading to very small Rh NPs of 2.2, 1.3 and 1.7 nm mean size, with PVP, PPh3 and dppb, respectively. The surface properties of these nanoparticles were compared using a model catalysis reaction namely, hydrogenation of cyclohexene, first under colloidal conditions and then under supported conditions after their immobilization onto an amino functionalized silica-coated magnetite support. PVP-stabilized Rh NPs were the most active catalyst whatever the catalytic conditions as a result of a strong coordination of the phosphine ligands at the metal surface that blocks some surface atoms even after several recycles of the supported nanocatalysts and limit the reactivity of the metallic surface

Anisotropic Panglial Coupling Reflects Tonotopic Organization in the Inferior Colliculus

Astrocytes and oligodendrocytes in different brain regions form panglial networks and the topography of such networks can correlate with neuronal topography and function. Astrocyte-oligodendrocyte networks in the lateral superior olive (LSO)—an auditory brainstem nucleus—were found to be anisotropic with a preferred orientation orthogonally to the tonotopic axis. We hypothesized that such a specialization might be present in other tonotopically organized brainstem nuclei, too. Thus, we analyzed gap junctional coupling in the center of the inferior colliculus (IC)—another nucleus of the auditory brainstem that exhibits tonotopic organization. In acute brainstem slices obtained from mice, IC networks were traced employing whole-cell patch-clamp recordings of single sulforhodamine (SR) 101-identified astrocytes and concomitant intracellular loading of the gap junction-permeable tracer neurobiotin. The majority of dye-coupled networks exhibited an oval topography, which was preferentially oriented orthogonal to the tonotopic axis. Astrocyte processes showed preferentially the same orientation indicating a correlation between astrocyte and network topography. In addition to SR101-positive astrocytes, IC networks contained oligodendrocytes. Using Na+ imaging, we analyzed the capability of IC networks to redistribute small ions. Na+ bi-directionally diffused between SR101-positive astrocytes and SR101-negative cells—presumably oligodendrocytes—showing the functionality of IC networks. Taken together, our results demonstrate that IC astrocytes and IC oligodendrocytes form functional anisotropic panglial networks that are preferentially oriented orthogonal to the tonotopic axis. Thus, our data indicate that the topographic specialization of glial networks seen in IC and LSO might be a general feature of tonotopically organized auditory brainstem nuclei

On the role of goal relevance in emotional attention: Disgust evokes early attention to cleanliness

Prior evidence has shown that aversive emotional states are characterised by an attentional bias towards aversive events. The present study investigated whether aversive emotions also bias attention towards stimuli that represent means by which the emotion can be alleviated. We induced disgust by having participants touch fake disgusting objects. Participants in the control condition touched nondisgusting objects. The results of a subsequent dot-probe task revealed that attention was oriented to disgusting pictures irrespective of condition. However, participants in the disgust condition also oriented towards pictures representing cleanliness. These findings suggest that the deployment of attention in aversive emotional states is not purely stimulus driven but is also guided by the goal to alleviate this emotional state