Two independent and primitive envelopes of the bilobate nucleus of comet 67P.

The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes. Here we report that the comet's major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov-Gerasimenko is an accreted body of two distinct objects with 'onion-like' stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov-Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.

Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse.

Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.

The Comet Interceptor Mission.

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.

Medium-term outcome of medial patellofemoral ligament reconstruction using synthetic graft.

BACKGROUND: Recurrent patella instability is a common and debilitating condition which affects mainly adolescents and young adults. Medial patellofemoral ligament (MPFL) reconstruction is the most popular surgical treatment for recurrent patella instability. The most common graft choice in the literature is ipsilateral hamstring tendon (gracilis or semitendinosis) but the complication rate remains high (11-26%). Conversely, there are very few papers on the use of modern, synthetic grafts. METHODS: A total of 85 patients who underwent MPFL reconstruction using a modern, synthetic graft (Xiros, UK) from 2014 to 2022 were retrospectively reviewed. Exclusion criteria were patella alta, malalignment, trochlea dysplasia and significant pain between episodes of instability. The author has developed an operative technique which is anatomic, minimally invasive and reproducible. Pre- and post-operative Kujala and Oxford knee scores were collected and analysed. RESULTS: The male to female ratio was 27:58, the average age was 28 years, and the follow up range was 1-9 years (mean follow up 4.84 years). We found a statistically significant improvement in mean Kujala and Oxford knee scores (P < 0.001) postoperatively. No major complications such as knee stiffness, soft tissue reaction, re-dislocation, patella fracture were identified in the series. There were nine minor complications (10.6%): five cases of medial knee pain, two cases of residual instability and two of superficial infection. CONCLUSION: This study demonstrates that modern, synthetic graft is a viable option for MPFL reconstruction. The technique described, achieves good clinical outcomes with low complication rates when compared with the published literature.

Sialic acid and anti-ganglioside M1 antibodies are invaluable biomarkers correlated with the severity of autism spectrum disorder.

BACKGROUND: Autism spectrum disorders (ASD) are devastating neurodevelopmental disorders that showed global increased prevalence. They are characterized by impairment of social communication and stereotyped patterns. OBJECTIVE: This study aimed at measuring the levels of total sialic acid (SA) and anti-ganglioside M1 (anti- GM1) IgG antibodies as essential biomarkers in a cohort of children with ASD to identify their diagnostic yield as well as their correlation with the severity of autistic behaviors. METHODS: The demographic characteristics, anthropometric measurements, and clinical data were recorded. The levels of total plasma SA and serum anti-GM1 IgG antibodies levels were measured in 100 children with ASD and 100 healthy controls. The severity of ASD-related symptoms was assessed by using the Childhood Autism Rating Scale (CARS). RESULTS: Children with ASD had significantly higher levels of both SA and anti-GM1 antibodies than healthy controls (p < 0.001). SA showed a statistically significant moderate diagnostic performance while anti-GM1 antibody showed a statistically significant high diagnostic in differentiating severe from mild to moderate autism. Moreover, both SA and anti-GM1 antibodies levels were significantly correlated to the severity of ASD symptoms (p < 0.001). CONCLUSION: The significantly increased levels of SA and anti-GM1 antibodies in children with ASD and their correlation with autism-related symptoms suggest their possible etiopathogenic role in autism as one of the pediatric autoimmune neuropsychiatric disorders. However, further large-scale studies are still needed to explore their possible bidirectional relationship as biomarkers for autism.

Clinical Outcome of Percutaneous Intramedullary Fixation for Midshaft Clavicular Fractures Using Elastic Stable Nails.

BACKGROUND: This study investigated the clinical outcomes of fixation of displaced middle-third clavicular fractures using percutaneous elastic stable intramedullary nails. MATERIAL AND METHODS: This study included sixty patients with a mean age of 26.40 ± 8.91 years (16-53 years) presented with a displaced middle third fracture of the clavicle. According to the Robinson classification, 48 cases (80%) were type 2B1, 9 cases (15%) type 2B2 and 3 case (5%) 2A1. All cases were treated by elastic intramedullary nails and followed up for at least 12 months. RESULTS: At the end of the twelve months' follow-up period, the mean Constant Shoulder score was 95.70 ± 13.55, ranging from 48 to 100. 54 patients (90%) had excellent results, 3 patients (5%) had an adequate result and 3 patients (5%) had a poor result. There was a statistically significant relationship between the final score and age and associated medical conditions. CONCLUSIONS: 1. Elastic Stable Intramedullary Nailing is an image-dependent procedure indicated best for young medically free athletes with simple 2-part middle third clavicle fracture. 2. Hammering is not recommended to avoid dorsolateral cortex perforation. 3. The most common complication is medial skin irritation because of the subcutaneous position of the clavicle as well as the sharp end of the cut nail.

Body composition, phenotype and central obesity indices in Egyptian women with non-alcoholic fatty liver disease.

OBJECTIVES: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. The aim of this study is to investigate body composition and phenotype of Egyptian women with non-alcoholic fatty liver disease (NAFLD) and compare with those without and determine the optimal cut-off values of central obesity indices for predicting NAFLD. METHODS: The study included 100 women with NAFLD and 100 age and sex matched healthy controls without NAFLD. All women were subjected to ultrasonography examination. Anthropometric measurements included weight, height, waist circumference (WC), hip circumference (HC) and skinfolds thickness were assessed for all participants. Body fat % was evaluated by Tanita body composition analyzer. Body mass index (BMI), WC / height ratio (WHtR), WC / HC ratio (WHR) and visceral adiposity index (VAI) were calculated. Receiver-operating characteristic (ROC) curve was used to determine the optimal cut-off values. RESULTS: Data showed significant higher levels of WHtR, WHR, BMI, sum of skinfolds, body fat %, serum fasting blood lipids and glucose in NAFLD women compared to group of patients without NAFLD. The area under curve (AUC) was 0.920 for VIA, 0.883 for WHtR and 0.647 for WHR. The optimal cutoff value of VAI was 3.66, of WHtR was 0.66 and WHR was 0.84. All values showed high sensitivity and specificity values. CONCLUSION: NAFLD women were obese, had excess subcutaneous fat and body fat ratio. Central obesity indices are closely associated with the presence of NAFLD in Egyptian women and might be responsible for its development. Visceral adiposity index had superior diagnostic performance.

Clinical Outcome of Fixed Versus Adjustable Loop Cortical Suspension Devices in Arthroscopic Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction has remained the gold standard for ACL injuries, especially for young individuals and athletes exposed to high level sporting activities aiming to return to their preinjury level of activity. Cortical suspensory femoral fixation is commonly performed for graft fixation to the femur in anterior cruciate ligament reconstruction using hamstring tendons. The aim of this study was to compare the clinical results of using fixed and adjustable loop cortical suspension devices in arthroscopic ACL reconstruction using the Lysholm Knee Scoring Scale after 12 months postoperatively. MATERIAL AND METHODS: This study included a total of sixty patients who underwent transportal arthroscopic ACL reconstruction using a hamstring tendon autograft from November 2016 to December 2017. For femoral graft fixation, a fixed-length loop device was used in 30 patients (fixed-loop group) and an adjustable-length loop device was used in 30 patients (adjustable-loop group) randomly.For tibial graft fixation, interference screw was used for all patients. RESULTS: The present study shows that there was no statistically significant difference between the two groups regarding the Lysholm score with highly statistically significant difference between preoperative and postoperative Lysholm score in each group separately. CONCLUSION: Both fixed loop and adjustable loop devices in ACL reconstruction provided good clinical outcomes but without significant statistical difference between both groups from the clinical point of view postoperatively using the Lysholm score.

Association between Myeloperoxidase Levels and Risk of Insulin Resistance in Egyptian Obese Women.

BACKGROUND: Myeloperoxidase (MPO) is an enzyme involved in the pathogenesis of several diseases. AIM: The current study aimed to investigate serum MPO levels in obese Egyptian women and assess its relation with insulin resistance (IR) and other biochemical risk parameters. METHODS: The study included 80 obese women and 50 age-and-sex-matched healthy controls. Insulin resistance (IR) was evaluated by the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR). Serum MPO, fasting glucose, insulin and blood lipids and anthropometry were measured. Obese cases were divided into three groups based on MPO tertiles. ROC analysis was performed to obtain the optimal cut-off values of MPO to predicate IR in obese women. RESULTS: The mean serum MPO was significantly higher in obese cases than controls. Cases in the highest MPO tertile had higher HOMA-IR, blood lipids and pressure levels compared with those in the lower tertile. The cutoff point of MPO was > 87.8 (ng/mL) and area under curves was 0.82 (p < 0.01) for diagnosis of IR. MPO levels were higher in obese Egyptian women than healthy controls. CONCLUSION: Elevation of MPO was associated with abnormal metabolic parameters. MPO might be used as an earlier biomarker for IR and metabolic disturbance in obese women.

Serum soluble receptor of advanced glycation end products and risk of metabolic syndrome in Egyptian obese women.

Obesity is one of the diagnostic criteria of metabolic syndrome (MS). It is correlated with insulin resistance (IR) and high vascular risk as well. Advanced glycation end products (AGEs) and their receptor (RAGE) play an important role in abnormal metabolic components in obese women. This study aimed to explore the serum levels of sRAGE in Egyptian obese women and compare with healthy non-obese controls and investigate the relationship between serum sRAGE, metabolic parameters, and obesity complications. The soluble form of receptor for advanced glycation end products (sRAGE), anthropometry, metabolic and biochemical biomarkers were measured in 100 obese women and 100 age-matched healthy control non-obese women. The homeostasis model assessment estimate of insulin resistance (HOMA-IR) has been determined from serum insulin and glucose values. Serum sRAGE levels were significantly lower in obese cases than controls and inversely correlated with obesity and metabolic parameters. Results of univariate and multivariate analyses for determinants of serum sRAGE levels in obese cases showed that parameters statistically and significantly related were body mass index (BMI), waist circumference (WC), LDL-C, TG, BP, HOMA-IR, ALT and AST. sRAGE is a novel biomarker for metabolic dysfunction in Egyptian obese women and might predict the future cardio-metabolic events.

Serum apelin levels and metabolic risk markers in obese women.

BACKGROUND: Adipose tissue hormones, Adipokines, play an important role in obesity-associated complications. Apelin has recently been added to the family of adipokines. The aim of this study was to evaluate the relationship between serum apelin levels and metabolic abnormal parameters in Egyptian obese women. MATERIALS AND METHODS: The study included 400 unrelated women; they were 200 obese women and 200 non- obese matched healthy women. All participants underwent clinical, anthropometric and biochemical examinations. Insulin resistance (IR) was determined by the homeostasis model assessment of insulin resistance (HOMA-IR). Serum apelin levels and obesity biomarkers were measured using enzyme-linked immunoassay (ELISA) kits. Fat mass was measured by Tanita Body Composition Analyzer. RESULTS: Obese women showed significant higher levels of serum apelin, leptin, triglycerides, LDL-C, total cholesterol, fasting insulin HOMA-IR and blood pressure levels than controls. Significant positive correlations between apelin and leptin levels with abnormal metabolic markers were noted in obese women. CONCLUSION: The present study suggests the significant role that might be mediated by apelin for developing abnormal metabolic parameters among Egyptian obese women.

Cometary science. The morphological diversity of comet 67P/Churyumov-Gerasimenko.

Images of comet 67P/Churyumov-Gerasimenko acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) imaging system onboard the European Space Agency's Rosetta spacecraft at scales of better than 0.8 meter per pixel show a wide variety of different structures and textures. The data show the importance of airfall, surface dust transport, mass wasting, and insolation weathering for cometary surface evolution, and they offer some support for subsurface fluidization models and mass loss through the ejection of large chunks of material.

Cement filling control and bone marrow removal in vertebral body augmentation by unipedicular aspiration technique: an experimental study using leakage model.

STUDY DESIGN: Experimental design using a laboratory leakage model. OBJECTIVE: To examine that a new aspiration technique, with a double conduit cannula design, improves the uniformity of cement filling, thus significantly reducing the risk of extraosseous leakage. SUMMARY OF BACKGROUND DATA: In vertebral augmentation, understanding the forces governing the intravertebral cement flow is essential for controlling the cement formation. A path of least resistance posed by the irregularities in the bone matrix or vertebral shell increases the risk of leak. We have previously shown that using viscous cement reduces the leakage risk. However, this may damage the already weak bone due to the high forces required for the cement to enter the bone cavities. METHODS: An experimental leakage model for vertebral augmentation was used-with a path, simulating a blood vessel, to provoke leakage. A novel cannula with 2 concentric conduits was used. The inner conduit is used for cement delivery and the outer conduit for aspiration. A mixed level with 2 factors (2 x 2(2)) experiment design was used to examine the ability of aspiration to direct the cement flow in both low and high viscous cement regimes. RESULTS: Aspiration significantly enhanced the filling uniformity and reduced the risk of leakage. The reduction in leak with the suction simultaneous to the injection for low viscosity cement, elapsed time 4 minutes, was 1.5 cc (alpha = 0.05). In the suction experiments, the reduction in leakage as compared with the reference condition for the 8 minutes elapsed time was 0.5 cc, (alpha = 0.05). CONCLUSION: The aspiration technique combined with a new cannula design improved the uniformity of filling. The aspiration technique helps in removal of the displaced bone marrow or tumor tissue. The aspiration applied with the new cannula requires only a single incision. Thus, it does not result in an increased invasiveness.