Equine digital tendons show breed‐specific differences in their mechanical properties that may relate to athletic ability and predisposition to injury

Background Throughout the ages, human subjects have selected horse breeds for their locomotor capacities. Concurrently, tissue properties may have diversified because of specific requirements of different disciplines. Objectives The aim of this study was to compare the biomechanical properties of tendons with different functions between equine breeds traditionally selected for racing or sport. Study design This study used ex vivo tendons and compared the mechanical properties of the common digital extensor tendon (CDET) and superficial digital flexor tendon (SDFT) between racehorses (Thoroughbred [TB]) and sports horses (Friesian Horse [FH], Warmblood [WB]). Methods The SDFT and CDET of FH (n = 12), WBs (n = 12) and TBs (n = 8) aged 3-12 years were harvested. The cross sectional area (cm(2)), maximal load (N), ultimate strain (%), ultimate stress (MPa) and elastic modulus (MPa) were determined and tested for significant differences between the breeds (P<0.05). Results The SDFT from WB horses had a significantly lower elastic modulus than TB horses and failed at a higher strain and load than both FHs and TBs. The mechanical properties of the CDET did not differ between breeds. In agreement with previous studies, the CDET failed at a higher stress and had a higher elastic modulus than the SDFT and, for the WB group of horses only, failed at a significantly lower strain. Interestingly, the mode of failure differed between breeds, particularly with respect to the FHs. Main limitations The exercise history of horses used in this study was unknown and the age-range was relatively large; both these factors may have influenced the absolute properties reported in this study. Conclusions This study shows for the first time that mechanical properties of the SDFT differ between breeds. These properties are likely to be related to selection for high-speed vs. an extravagant elastic gait and may be an important indicator of performance ability. The is available in Spanish - see Supporting Informatio

Using size-selected gold clusters on graphene oxide films to aid cryo-transmission electron tomography alignment

A three-dimensional reconstruction of a nano-scale aqueous object can be achieved by taking a series of transmission electron micrographs tilted at different angles in vitreous ice: cryo-Transmission Electron Tomography. Presented here is a novel method of fine alignment for the tilt series. Size-selected gold clusters of ~2.7 nm (Au(561 ± 14)), ~3.2 nm (Au(923 ± 22)), and ~4.3 nm (Au(2057 ± 45)) in diameter were deposited onto separate graphene oxide films overlaying holes on amorphous carbon grids. After plunge freezing and subsequent transfer to cryo-Transmission Electron Tomography, the resulting tomograms have excellent (de-)focus and alignment properties during automatic acquisition. Fine alignment is accurate when the evenly distributed 3.2 nm gold particles are used as fiducial markers, demonstrated with a reconstruction of a tobacco mosaic virus. Using a graphene oxide film means the fiducial markers are not interfering with the ice bound sample and that automated collection is consistent. The use of pre-deposited size-selected clusters means there is no aggregation and a user defined concentration. The size-selected clusters are mono-dispersed and can be produced in a wide size range including 2–5 nm in diameter. The use of size-selected clusters on a graphene oxide films represents a significant technical advance for 3D cryo-electron microscopy

Gut Microbiota Composition of Biliary Atresia Patients Before Kasai Portoenterostomy Associates With Long-term Outcome

BACKGROUND AND AIMS: Biliary atresia (BA) is a cholestatic, fibro-obliterative cholangiopathy of unknown etiology. BA is primarily treated by a surgical approach, i.e. the Kasai portoenterostomy (KPE), to obtain clearance of jaundice (COJ). The gut microbiota (GM) composition has been associated with the course of several cholestatic liver diseases. It is largely unknown, however, whether GM composition associates with the outcome of KPE. We compared the GM composition of BA patients and controls and assessed if GM composition before KPE was related to COJ after KPE. METHODS: We compared feces of term born BA patients before KPE and controls (patients undergoing inguinal hernia repair) by 16S rRNA sequencing. Composition and alpha diversity of the GM were compared between BA and controls before KPE and after KPE, between patients with COJ vs. without COJ (total serum bilirubin < or ≥ 20 μmol/L < 6mo post-KPE). RESULTS: Alpha diversity was comparable between BA (n = 12, age 1.6[1.3-1.8]mo) and controls (n = 6, age 2.0[1.4-2.1]mo; P = 0.22). Compared to controls, BA patients had lower abundances of Bifidobacteriaceae (β=-1.98, P < 0.001) and Lachnospiraceae (β=-1.84, P = 0.007), and higher abundances of Streptococcus (β=1.13, P = 0.003). The alpha diversity prior to KPE correlated negatively with COJ (R = -0.63, P = 0.03). Lower alpha diversity pre-KPE was associated with COJ [+] (βlogit = -0.64, P = 0.04). We observed greater abundances of genus Acinetobacter (β=1.27, P = 0.03) and family Clostridiaceae (β=1.45, P = 0.03) and lower abundances of the family Enterobacteriaceae, (genera Klebsiella (β=-1.21, P = 0.01), Salmonella (β=-1.57, P = 0.02)) in COJ [+] vs. COJ [-]. CONCLUSIONS: The gut microbiota of biliary atresia patients prior to Kasai portoenterostomy associates with outcome, clearance of jaundice, suggestive of predictive and mechanistic roles of the gut microbiota composition in bile homeostasis

Long-Term Neurodevelopmental Outcomes in Children with Biliary Atresia

Objective: To assess long-term neurodevelopmental outcomes in school-aged children with biliary atresia. Study design: All Dutch children (6-12 years of age) diagnosed with biliary atresia were invited to participate in this study. We used validated neurodevelopmental tests to assess motor skills and cognition, and questionnaires to assess behavior. Scores were compared with the Dutch norm population, by means of 1-sample tests. Results are given as number and percentage or mean ± SD. Results: We included 46 children, with a median age of 11 years (range, 6-13 years); 36 children had undergone a liver transplantation (78%). Twelve children (26%) received special education (vs 2.4% in the norm population; P <.01). Motor outcomes were significantly affected compared with the norm population (P <.01), with 25% normal (vs 85%), 25% borderline (vs 10%), and 50% low scores (vs 5%). Total IQ was lower in patients with biliary atresia, compared with the norm population (91 ± 18 vs 100 ± 15; P <.01). There were no significant differences in test scores between children with native liver and after liver transplantation. Conclusions: School-aged children with biliary atresia show neurodevelopmental impairments compared with the norm population, especially in motor skills. Our data strongly warrant evaluation of neurodevelopmental intervention programs to assess whether long-term outcomes could be improved

Computational spatiotemporal analysis identifies WAVE2 and cofilin as joint regulators of costimulation-mediated T cell actin dynamics

Fluorescence microscopy is one of the most important tools in cell biology research and it provides spatial and temporal information to investigate regulatory systems inside cells. This technique can generate data in the form of signal intensities at thousands of positions resolved inside individual live cells; however, given extensive cell-to-cell variation, methods do not currently exist to assemble these data into three- or four-dimensional maps of protein concentration that can be compared across different cells and conditions. Here, we have developed one such method and applied it to investigate actin dynamics in T cell activation. Antigen recognition in T cells by the T cell receptor (TCR) is amplified by engagement of the costimulatory receptor CD28 and we have determined how CD28 modulates actin dynamics. We imaged actin and eight core actin regulators under conditions where CD28 in the context of a strong TCR signal was engaged or blocked to yield over a thousand movies. Our computational analysis identified diminished recruitment of the activator of actin nucleation WAVE2 and the actin severing protein cofilin to F-actin as the dominant difference upon costimulation blockade. Reconstitution of WAVE2 and cofilin activity restored the defect in actin signaling dynamics upon costimulation blockade. Thus we have developed and validated an approach to quantify protein distributions in time and space for analysis of complex regulatory systems

Smc5/6: a link between DNA repair and unidirectional replication?

Of the three structural maintenance of chromosome (SMC) complexes, two directly regulate chromosome dynamics. The third, Smc5/6, functions mainly in homologous recombination and in completing DNA replication. The literature suggests that Smc5/6 coordinates DNA repair, in part through post-translational modification of uncharacterized target proteins that can dictate their subcellular localization, and that Smc5/6 also functions to establish DNA-damage-dependent cohesion. A nucleolar-specific Smc5/6 function has been proposed because Smc5/6 yeast mutants display penetrant phenotypes of ribosomal DNA (rDNA) instability. rDNA repeats are replicated unidirectionally. Here, we propose that unidirectional replication, combined with global Smc5/6 functions, can explain the apparent rDNA specificity

Routine Postoperative Antithrombotic Therapy in Pediatric Liver Transplantation:Impact on Bleeding and Thrombotic Complications

BACKGROUND:  Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) are serious causes of morbidity and mortality after pediatric liver transplantation. To reduce thrombotic complications, routine antithrombotic therapy consisting of 1 week heparin followed by 3 months acetylsalicylic acid, was implemented in our pediatric liver transplant program in 2003. This study aimed to evaluate incidences of bleeding and thrombotic complications since the implementation of routine antithrombotic therapy and to identify risk factors for these complications. METHODS:  This retrospective cohort study includes 200 consecutive pediatric primary liver transplantations performed between 2003 and 2016. Uni- and multivariate logistic regression analysis, Kaplan-Meier method, and Cox regression analysis were used to evaluate recipient outcome. RESULTS:  HAT occurred in 15 (7.5%), PVT in 4 (2.0%), and venous outflow tract thrombosis in 2 (1.0%) recipients. Intraoperative vascular interventions (odds ratio [OR] 14.45 [95% confidence interval [CI] 3.75-55.67]), low recipient age (OR 0.81 [0.69-0.95]), and donor age (OR 0.96 [0.93-0.99]) were associated with posttransplant thrombosis. Clinically relevant bleeding occurred in 37%. Risk factors were high recipient age (OR 1.08 [1.02-1.15]), high Child-Pugh scores (OR 1.14 [1.02-1.28]), and intraoperative blood loss in mL/kg (OR 1.003 [1.001-1.006]). Both posttransplant thrombotic (hazard ratio [HR] 3.38 [1.36-8.45]; p = 0.009) and bleeding complications (HR 2.50 [1.19-5.24]; p = 0.015) significantly increased mortality. CONCLUSION:  In 200 consecutive pediatric liver transplant recipients receiving routine postoperative antithrombotic therapy, we report low incidences of posttransplant vascular complications. Posttransplant antithrombotic therapy seems to be a valuable strategy in pediatric liver transplantation. Identified risk factors for bleeding and thrombotic complications might facilitate a more personalized approach in antithrombotic therapy

Indeterminate pediatric acute liver failure:Clinical characteristics of a temporal cluster of five children in the Netherlands in the spring of 2022

There is increasing global concern of severe acute hepatitis of unknown etiology in young children. In early 2022, our center for liver transplantation in the Netherlands treated five children who presented in short succession with indeterminate acute liver failure. Four children underwent liver transplantation, one spontaneously recovered. Here we delineate the clinical course and comprehensive diagnostic workup of these patients. Three of five patients showed a gradual decline of liver synthetic function and had mild neurological symptoms. Their clinical and histological findings were consistent with hepatitis. These three patients all had a past SARS-CoV-2 infection and two of them were positive for adenovirus DNA. The other two patients presented with advanced liver failure and encephalopathy and underwent dialysis as a bridge to transplantation. One of these children spontaneously recovered. We discuss this cluster of patients in the context of the currently elevated incidence of severe acute hepatitis in children

Maintenance of complex I and its supercomplexes by NDUF-11 is essential for mitochondrial structure, function and health

Mitochondrial supercomplexes form around a conserved core of monomeric complex I and dimeric complex III; wherein a subunit of the former, NDUFA11, is conspicuously situated at the interface. We identified nduf-11 (B0491.5) as encoding the Caenorhabditis elegans homologue of NDUFA11. Animals homozygous for a CRISPR-Cas9-generated knockout allele of nduf-11 arrested at the second larval (L2) development stage. Reducing (but not eliminating) expression using RNAi allowed development to adulthood, enabling characterisation of the consequences: destabilisation of complex I and its supercomplexes and perturbation of respiratory function. The loss of NADH dehydrogenase activity was compensated by enhanced complex II activity, with the potential for detrimental reactive oxygen species (ROS) production. Cryo-electron tomography highlighted aberrant morphology of cristae and widening of both cristae junctions and the intermembrane space. The requirement of NDUF-11 for balanced respiration, mitochondrial morphology and development presumably arises due to its involvement in complex I and supercomplex maintenance. This highlights the importance of respiratory complex integrity for health and the potential for its perturbation to cause mitochondrial disease. This article has an associated First Person interview with Amber Knapp-Wilson, joint first author of the paper

Novel standards in the measurement of rat insulin granules combining electron microscopy, high-content image analysis and in silico modelling

Knowledge of number, size and content of insulin secretory granules is pivotal for understanding the physiology of pancreatic beta cells. Here we re-evaluated key structural features of rat beta cells, including insulin granule size, number and distribution as well as cell size