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Parallel geodesics and minimal stable length of random groups
No full text21 pagesWe show that for any pair of long enough parallel geodesics in a random group G(m, d) with m generators at density d < 1/6, there is a van Kampen diagram having only one layer of faces. Using this result, we give an upper bound, depending only on d, of the number of pairwise parallel geodesics in G(m, d) when d < 1/6. As an application, we show that the minimal stable length of a random group at density d < 1/6 is exactly 1
Cemented Fixation in Arthroplasty for Hip Fractures Does Not Increase Cardiopulmonary Complications: A Secondary Analysis of the HIP ATTACK Trial
No full textInternational audienceBackground Cemented fixation in arthroplasty to treat hip fractures is now widely recommended, but it is not universally used. Some surgeons may feel that the risk of bone cement implantation syndrome and its cardiopulmonary sequalae are too high, in part, because the evidence provides little detail on postoperative myocardial injury and other medical complications after cement use. Questions/purposes We aimed to use data from the HIP ATTACK trial (an RCT in which patients with a hip fracture were randomized to accelerated time to surgery versus normal timing of surgery) for a secondary analysis to answer the following questions on arthroplasty for patients with hip fractures: (1) Are patients who undergo cemented hip arthroplasty for hip fractures more likely to experience cardiopulmonary events than patients who undergo uncemented hip arthroplasty? (2) Are patients who undergo cemented hip arthroplasty for hip fractures more likely to experience myocardial injury, identified by elevated troponin levels, than patients who undergo uncemented hip arthroplasty? Methods We performed a post hoc analysis of the HIP ATTACK trial for a subset of patients who were treated with THA or hemiarthroplasty for a femoral neck fracture because the trial collected postoperative troponin levels to allow us to identify myocardial injury. The HIP ATTACK trial consisted of 2970 patients. We limited our source cohort to the 1049 patients who underwent hip arthroplasty and were not lost to follow-up (four patients who had undergone arthroplasty were lost to follow-up). We excluded two patients with unknown fixation and six patients with “other arthroplasty.” We limited our analysis to femoral neck fractures, which excluded 75 more patients. Of the 966 patients who received hip arthroplasty, 61% (593) had cemented fixation. Patients with cemented fixation were older than patients with cementless fixation (median [IQR] 82 (74 to 88) versus 79 (71 to 86); p = 0.003). Race was self-reported by patients and differed between patients with cemented and cementless fixation. A higher proportion of patients who received cementless fixation had undergone THA (compared with hemiarthroplasty) than patients in the cemented fixation group (24% [91] versus 11% [66]; p < 0.001). We used logistic regression to estimate the association between cement use and a composite outcome consisting of all-cause mortality and various cardiopulmonary outcomes. We included cardiopulmonary outcomes possibly associated with bone cement implantation syndrome; there were only a small number of patients who had only nonsevere outcomes. We had 80% power to detect an OR of ≥ 1.6. We adjusted for all baseline differences between both groups except for anesthesia (as it was not associated with the outcome) and duration of surgery (as it is a function of cement use). Results After controlling for age, sex, race, and relevant comorbidity, we found that cement use was not associated with differences in the composite outcome at 90 days (OR 1.0 [95% confidence interval (CI) 0.7 to 1.4]; p = 0.99) or 1 year (OR 1.0 [95% CI 0.7 to 1.4]; p = 0.95) or with postoperative elevated troponin (OR 1.4 [95% CI 1.0 to 1.9]; p = 0.06) on Day 1. Conclusion There was no difference in cardiopulmonary outcomes among patients with arthroplasty to treat their hip fracture by fixation method. These findings further support the recommendations to use cemented femoral fixation in THA and hemiarthroplasty for patients with hip fractures. Surgeons with limited experience with cemented femoral fixation should familiarize themselves with these skills. Future studies should assess what barriers to cemented fixation exist and how they can be mitigated. Level of Evidence Level III, therapeutic study
The effects of over‐ and under‐stuffing the anterior knee compartment in primary TKA: A systematic review
No full textInternational audienceAbstract Purpose Up to 20% of patients remain dissatisfied following total knee arthroplasty (TKA), often due to anterior knee pain (AKP) and other patellofemoral complications. Several studies highlighted risks of over‐ or under‐stuffing within the patellofemoral compartment, yet there are no standardised methods for their assessment, and their effects on patient‐reported outcome measures (PROMs) remain unclear. The aim of this review was to synthesise and critically appraise all published studies that investigated effects of over‐ and under‐stuffing the anterior compartment on PROMs following primary TKA. Methods The protocol for this systematic review followed PRISMA guidelines was registered on PROSPERO (July 2024), before electronic searches by two readers (C.K. and V.G.) using Medline and Scopus. The authors included clinical studies published in English, reporting a quantifiable method to assess the anterior compartment in TKA, with clinical and/or radiographic outcomes. The authors excluded in vitro or ex vivo studies, reviews or editorials, studies on revision TKA and studies with follow‐up <1 year. Results Searches returned 160 records, of which 14 met the eligibility criteria (10 retrospective and 4 prospective), representing 4404 knees in 3718 patients. The primary outcome was over‐stuffing in five studies, which investigated its correlation with PROMs and/or AKP, while the primary outcome was under‐stuffing in two studies. The PROMs reported were Western Ontario and McMaster Universities Osteoarthritis Index (eight studies), knee society score (six studies), knee injury and osteoarthritis outcome score (two studies), as well as Oxford knee score, forgotten joint score and Kujala scores (each one study). Only two studies used dynamic assessments, while 12 used static assessments. Only 3 of the 14 studies found significant effects of over‐stuffing (by >5 mm) on PROMs. Conclusions Changes in anterior offset, particularly over‐stuffing, may cause patellofemoral complications. Although it would be ideal to restore the anterior compartment, small deviations do not affect clinical outcomes. A threshold of 5 mm could represent the ‘safe zone’ for change in anterior offset in patients undergoing TKA. Level of Evidence Level III
Hydrodynamic limit for an open facilitated exclusion process with slow and fast boundaries
No full text44 pagesInternational audienceWe study the symmetric facilitated exclusion process (FEP) on the finite one-dimensional lattice {1, . . . , N − 1} when put in contact with boundary reservoirs, whose action is subject to an additional kinetic constraint in order to enforce ergodicity, and whose speed is of order N^{−θ} for some parameter θ. We derive its hydrodynamic limit as N goes to infinity, in the diffusive space-time scaling, when the initial density profile is supercritical. More precisely, the macroscopic density of particles evolves in the bulk according to a fast diffusion equation as in the periodic case, which is now subject to boundary conditions that can be of Dirichlet, Robin or Neumann type depending on the parameter θ. In the Dirichlet case, the FEP exhibits a very peculiar behaviour: unlike for the classical SSEP, and due to the two-phased nature of FEP, the reservoirs impose boundary densities which do not coincide with their equilibrium densities. The proof is based on the classical entropy method, but requires significant adaptations to account for the FEP’s non-product stationary states and to deal with the non-equilibrium settin
Le laboureur et ses outils dans le glossaire gréco-copte de Dioscore d’Aphrodité (VIe siècle apr. J.-C.) : une source retrouvée, Hésiode, Les travaux et les jours, 427-439 et 467-469
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A Recombinant Elastic Peptide Rescues Elasticity From a Self‐Assembled Dermal Sheet Model Treated With Ascorbic Acid
No full textInternational audienceABSTRACT The extracellular matrix (ECM) plays a pivotal role in determining the structure and function of the skin. Collagen and elastin, in particular, are responsible for providing tensile strength and elasticity, respectively. However, imbalances in the components of the extracellular matrix (ECM) during tissue engineering often result in the deterioration of the mechanical properties and physiological relevance of dermal substitutes, in part due to the detrimental effect of ascorbic acid (AA) on elastic fibre biosynthesis. The objective of this study is to investigate the potential of a synthetic elastic protein (SEP) to improve ECM remodelling and to restore the equilibrium between collagen and elastin in reconstructed dermal tissues. Primary fibroblasts monolayers were treated with increasing concentrations of SEP in the presence or not of AA without affecting cytotoxicity. Western blot and immunofluorescence analyses showed that in the presence of AA – which typically reduced elastin synthesis‐ SEP improved elastic fibre formation without affecting type I collagen assembly. Additionally, 3D dermal substitutes treated with SEP and AA were analysed at the ultrastructural scale showing a specific colocalization of SEP with fibrillin‐rich fibrils. Finally, dynamic mechanical analyses were conducted to measure mechanical properties of decellularized ECM. In the presence of SEP, we observed an increase of 46% and 40% of elastic and Young's moduli respectively. By restoring ECM integrity, SEP is emerging as a promising biomimetic tool for the development of 3D skin substitutes. Its application has the potential to improve the physiological relevance and therapeutic value of engineered skin tissues
Impact of a brief HRV-biofeedback intervention on emotion regulation following a real-life stressful event: A randomized controlled study
No full textInternational audienceAlthough studies indicate that Heart Rate Variability Biofeedback (HRV-BFB) interventions seem to increase physiological regulation, their effects on broader aspects of emotion regulation during stress recovery remain inconsistent. The aim of the current study was to investigate the effect of a brief 6-min HRV-BFB intervention on different aspects of emotion regulation and well-being after exposure to a real-life stressor
Agromining of Nickel: Finally Becoming a Reality at Commercial Scale
No full textInternational audienceInitially proposed over 40 years ago, the biotechnology of agromining has had a long and tortuous gestational process on the way to becoming a proven commercial reality. The field has been marred by claims for unrealistic yields made by startup companies. Nevertheless, nickel agromining has become a viable business proposition for several companies now operating “metal farms” around the world. In this review, we provide a critical perspective on the current direction of the field and potential pitfalls still to overcome. Challenges and risks include the urgency for discovery of suitable metal crop species before extinction from habitat loss, the rapid domestication of wild species to be accommodated in regular cultivation systems, and the potential introduction and escape of non-native plant species. Initiatives to identify new hyperaccumulators using X-ray fluorescence scanning of herbarium collections should target the biodiversity hotspots of the world and should be coupled with ex situ conservation of threatened hyperaccumulator plant species in botanical gardens. With the rapid progress in the science needed to find and develop more effective hyperaccumulators, it is an exciting time for nickel agromining. The next few years are expected to be a make-or-break period in its transformation to a commercial reality
Comparison of individuals with radiologically isolated syndrome, early multiple sclerosis patients, and healthy controls using a digital neurological examination
No full textInternational audienceBackground: The revised McDonald criteria shifted toward the recognition of the radiologically isolated syndrome (RIS) as the first phase of the multiple sclerosis (MS) spectrum.Objectives: To characterize differences between RIS individuals, early MS patients, and healthy controls (HCs) using a high-precision clinical assessment tool based on digital technology.Methods: We performed a multicentric, cross-sectional study involving RIS, early MS patients, and HC. Subjects were assessed using Neuraccure, an iPad application capable of detecting subtle abnormalities in four neurological functions: hand coordination, low-contrast vision, reaction time, and eye movements.Results: In total, 565 individuals were included (MS: 255, RIS: 146, HC: 164). HC performed better than RIS and MS across all digital measures (p < 0.0001 to 0.03). There was no statistical difference between RIS and MS patients, except for the coordination test, which was slightly worse in MS patients (p = 0.03). The receiver operating characteristic (ROC) analysis indicated that the presence of at least two impaired functions could detect RIS and MS from HC with 83.2% sensitivity and 84.3% specificity. A higher number of impaired functions were associated with lower brain magnetic resonance imaging (MRI) volumes.Conclusion: High-precision neurological evaluation can distinguish HC from RIS and MS at an individual scale with a good performance
An embryo-derived peptide signal directs endosperm polarity in Arabidopsis
No full textAbstract Angiosperm seed formation requires the coordinated development of the products of double fertilization, the embryo and the endosperm. The endosperm mediates efficient nutrient transfer from surrounding maternal tissues to the developing embryo. This function requires a polarized tissue organization, which manifests as early polar gene expression and polar cellularization dynamics. We show that the receptor kinase HAIKU2 acts in coordination with the transcription factor WRKY10/MINISEED3 to ensure robust endosperm polarity establishment through the activity of the homeodomain transcription factors WUSCHEL-RELATED HOMEOBOX 8 and 9 . This process depends on egg cell fertilization and is mediated through the peptide PATHOGEN-INDUCED PEPTIDE-LIKE 7, which acts as a HAIKU2 ligand. Our results reveal how a molecular paracrine dialogue between the embryo and endosperm ensures optimal seed developmental coordination