Impact of contraception and IVF hormones on metabolic, endocrine, and inflammatory status

Assisted reproductive technologies (ART) represent commonly utilized management strategies for infertility with multifactorial causes (including genetically predisposed diseases). Amongst ART, in vitro fertilization (IVF) is the most popular. IVF treatment may predispose the mother to increased risks and complications during pregnancy, and there may be adverse fetal outcomes. Hormonal therapies, including oral contraceptives, may impair glucose and lipid metabolism, and promote insulin resistance and inflammation. IVF treatment involves administration of reproductive hormones, similar in composition but in much higher doses than those used for oral contraception. The provision of IVF reproductive hormones to mice associates with glucose intolerance. In addition, the physiological and hormonal changes of pregnancy can trigger an inflammatory response, and metabolic and endocrine changes. There is controversy regarding the potential effects of IVF hormonal therapies in the promotion of diabetogenic and inflammatory states, additional to those that occur during pregnancy, and which may therefore predispose women with IVF-conceived pregnancies to adverse obstetric outcomes compared with women with spontaneously conceived pregnancies. This review summarizes the limited published evidence regarding the effect of IVF-based fertility therapies on glucose homeostasis, insulin resistance, cardio-metabolic profile, and markers of inflammation

Development and validation of a composite material law for crash simulations

International audienceMore and more structural parts are building using organic matrix composite materials in order to reduce the weight of aircraft structures. In order to reduce the number of tests required at the different scale of the building block approach, an increase of the knowledge regarding strain rate dependency of such materials is still a topic of interest. Particularly most of the strain rate dependent material laws are based on or validated with tests performed on split Hopkinson bars [1,2]. Few results are available in the literature concerning the intermediate strain rate, typically ranging between 10-3 s-1 and 100 s-1. Consequently, this study is first dedicated to the experimental characterisation of the rate effect for this specific range of strain rate. For that purpose, tensile tests have been performed on a servo-hydraulic jack on off-axis specimens. Various off-axis angles have been considered: 15°, 30°, 45°, 60°, 75° and 90°. The geometry of the coupon for each angle has been defined thanks to a numerical study in order to reduce stress concentration near to the tabs and maximise the stress field homogeneity within the specimens. Three different loading speeds with at least three specimens were tested in order to evaluate discrepancy. A Photron SA-X high speed camera has been used to evaluate strain using a Digital Image Correlation software (Aramis GOM). Moreover, as multiple failure locations are observed for high loading rate tests, high speed imaging allow the localisation of the first failure.These results have been used in order to include rate dependency in an advanced material law initially proposed by ONERA for quasi-static loadings. This model written at the ply scale is based on a visco-elastic behaviour law until a ply failure criterion is reached. A Hashin like failure criterion is used and two failure modes are considered: fibre failure and matrix failure. The degradation of the ply properties is obtained with 2 damage variables: d1 for fibre failure and d2 for matrix failure. Improvements regarding rate dependency of this material law have been studied for its three main aspects: the visco-elastic behaviour, the failure criterion and the damage evolution law. Regarding the visco-elastic behaviour, previous works [3] have shown that a bi-spectral visco-elastic model is required in order to take into account the short relaxation times required to accurately described rate dependency for high strain rate tests and long relaxation times for low strain rate tests. The main drawback of this model is its computational cost due to the important number of viscous mechanisms that have to be considered. As full-scale crash simulation is the targeted application case, a modified version of this model has been proposed. It still has an accurate prediction of the different modulus evolutions with the loading rate but it has a reduce computational cost. Concerning the loading speed dependency of the failure criterion, dynamic off-axis tensile tests will be used as input data to analyse and improve the failure criterion. Finally, improvements of the different damage evolution laws will be based on results available in the literature [4]. Finally, this material law has been implemented in an explicit finite element code in order to validate it on more complex coupons

Effects of IVF therapies on metabolic, endocrine and inflammatory status in IVF-conceived pregnancy

Rationale In vitro fertilization (IVF) is a common treatment for infertility. In mice, IVF is associated with development of glucose intolerance. However, human data are limited regarding the metabolic, endocrine and inflammatory effects of IVF therapy in IVF‐conceived pregnancies. Objective To explore effects of IVF therapies on metabolic, endocrine and inflammatory parameters in IVF‐conceived pregnancy. Methodology Twelve‐week prospective observational study of adult normoglycaemic women, BMI 18.5‐38 kg/m2 and ≤ 39 years awaiting IVF therapy. Fasting blood samples were collected at baseline and 12 weeks, and serum analysed for reproductive hormones, glucose, lipids, insulin sensitivity, thyroid status, adiponectin inflammatory marker and lipopolysaccharide‐binding protein (LBP). Results Two hundred and seventy‐five women were analysed: 158 IVF‐conceived pregnant women and 117 with failed IVF. Compared with baseline, nonpregnant women had significant (P < .001) increases in 12‐week glucose (86.04‐87.62 mg/dL), insulin (8.72‐9.37 µIU/mL), HOMA‐IR (1.9‐2.1), T‐Chol (169.5‐174.9 mg/dL), TG (71.0‐83.7 mg/dL) and HDL‐C (52.0‐54.11 mg/dL) levels. At 12 weeks, pregnant women also had (P < .001) increases in T‐Chol (177.5‐199.5 mg/dL), TG (73.5‐126.78 mg/dL) and HDL‐C (55.3‐65.1 mg/dL), while a significant reduction in glucose (86.15‐82.19 mg/dL), HbA1c (5.3‐5.08%) and TSH (1.71‐1.36 µIU/mL) levels from baseline. Adiponectin and LBP levels remained the same in either group. Conclusion In vitro fertilization hormonal therapy impairs glucose and insulin levels; these effects are masked in early pregnancy. Changes in lipid profile occur following IVF therapies regardless of pregnancy outcome. Neither adiponectin nor LBP is affected by IVF therapies and during early IVF‐conceived pregnancy

Potentials and limitations of microorganisms as renal failure biotherapeutics

Renal insufficiency leads to uremia, a complicated syndrome. It thus becomes vital to reduce waste metabolites and regulate water and electrolytes in kidney failure. The most common treatment of this disease is either dialysis or transplantation. Although these treatments are very effective, they are extremely costly. Recently artificial cells, microencapsulated live bacterial cells, and other cells have been studied to manage renal failure metabolic wastes. The procedure for microencapsulation of biologically active material is well documented and offers many biomedical applications. Microencapsulated bacteria have been documented to efficiently remove urea and several uremic markers such as ammonia, creatinine, uric acid, phosphate, potassium, magnesium, sodium, and chloride. These bacteria also have further potential as biotherapeutic agents because they can be engineered to remove selected unwanted waste. This application has enormous potential for removal of waste metabolites and electrolytes in renal failure as well as other diseases such as liver failure, phenylketonuria, and Crohn’s disease, to name a few. This paper discusses the various options available to date to manage renal failure metabolites and focuses on the potential of using encapsulated live cells as biotherapeutic agents to control renal failure waste metabolites and electrolytes

Density hardening plasticity and mechanical aging of silica glass under pressure: A Raman spectroscopic study

In addition of a flow, plastic deformation of structural glasses (in particular amorphous silica) is characterized by a permanent densification. Raman spectroscopic estimators are shown to give a full account of the plastic behavior of silica under pressure. While the permanent densification of silica has been widely discussed in terms of amorphous-amorphous transition, from a plasticity point of view, the evolution of the residual densification with the maximum pressure of a pressure cycle can be discussed as a density hardening phenomenon. In the framework of such a mechanical aging effect, we propose that the glass structure could be labelled by the maximum pressure experienced by the glass and that the saturation of densification could be associated with the densest packing of tetrahedra only linked by their vertices

Oral Microencapsulated Live Saccharomyces cerevisiae Cells for Use in Renal Failure Uremia: Preparation and In Vivo Analysis

Orally administrable alginate-poly-L-lysine-alginate (APA) microcapsules containing live yeast cells was investigated for use in renal failure. At all times, yeast cells remain inside the microcapsules, which are then excreted in the stool. During their gastrointestinal passage, small molecules, like urea, diffuse into the yeast microcapsules where they are hydrolyzed. Orally administrating these microcapsules to uremic rats was found to decrease urea concentrations from 7.29 ± 0.89 mmol/L to 6.12 ± 0.90 mmol/L over a treatment period of eight weeks. After stopping the treatment, the urea concentrations increased back to uremic levels of 7.64 ± 0.77 mmol/L. The analysis of creatinine concentrations averaged 39.19 ± 4.33 μmol/L, 50.83 ± 5.55 μmol/L, and 50.28 ± 7.10 μmol/L for the normal-control, uremic-control and uremic-treatment groups, respectively. While creatinine concentrations for both uremic-control and uremic-treatment groups did not differ among each other (P > .05), they were, however, significantly higher than those of the normal control group (P < .05). Uric acid concentrations averaged 80.08 ± 26.49 μmol/L, 99.92 ± 26.55 μmol/L, and 86.49 ± 28.42 μmol/L for the normal-control, uremic-control and uremic-treatment groups, respectively. There were no significant differences in both calcium and phosphate concentrations among all three groups (P > .05). The microbial populations of five tested types of bacteria were not substantially altered by the presence of the yeast APA encapsulated yeast (P > .05)

Gut microbiota: next frontier in understanding human health and development of biotherapeutics

The gut microbiota is a remarkable asset for human health. As a key element in the development and prevention of specific diseases, its study has yielded a new field of promising biotherapeutics. This review provides comprehensive and updated knowledge of the human gut microbiota, its implications in health and disease, and the potentials and limitations of its modification by currently available biotherapeutics to treat, prevent and/or restore human health, and future directions. Homeostasis of the gut microbiota maintains various functions which are vital to the maintenance of human health. Disruption of the intestinal ecosystem equilibrium (gut dysbiosis) is associated with a plethora of human diseases, including autoimmune and allergic diseases, colorectal cancer, metabolic diseases, and bacterial infections. Relevant underlying mechanisms by which specific intestinal bacteria populations might trigger the development of disease in susceptible hosts are being explored across the globe. Beneficial modulation of the gut microbiota using biotherapeutics, such as prebiotics, probiotics, and antibiotics, may favor health-promoting populations of bacteria and can be exploited in development of biotherapeutics. Other technologies, such as development of human gut models, bacterial screening, and delivery formulations eg, microencapsulated probiotics, may contribute significantly in the near future. Therefore, the human gut microbiota is a legitimate therapeutic target to treat and/or prevent various diseases. Development of a clear understanding of the technologies needed to exploit the gut microbiota is urgently required

Mesure par thermographie infrarouge de l'influence de la vitesse sur l'endommagement diffus dans les matériaux composites

International audienceDans la gamme des vitesses lentes et quasi-statiques, la mesure de la densité de fissuration dans les matériaux composites stratifiés croisés à fait l’objet de nombreuses études. La plupart de ces techniques ont été utilisées dans le cadre de sollicitations cyclées où l’interruption de l’essai permet d’observer et de mesurer les mécanismes de dégradation du matériau au cours du chargement. Dans la gamme des vitesses dynamiques, le recours à de tels protocoles reste toutefois limité à cause de l’asservissement en boucle ouverte des moyens dynamiques. Dans ces travaux, afin de mesurer l’influence sur la cinétique de fissuration de l’augmentation de la vitesse vers des plages dynamiques, une technique de mesure non-intrusive par thermographie infrarouge (IR) est utilisée. Cette approche a notamment pu être utilisée pour mesurer l’évolution du dommage dans les composites soumis à des chargements statiques [1], de fatigues [2] et plus récemment à des chargements aux vitesses dynamiques intermédiaires [3]. Néanmoins, la détection et la quantification par thermographie IR de fissures transverses pour des chargements dynamiques restent encore peu étudiées dans la littérature du fait des limitations liées à la fréquence d’acquisition des caméras IR d’ancienne génération. Ces travaux proposent ainsi d’étendre l’analyse réalisée à basses vitesses dans les travaux de [4] à des vitesses de sollicitations dynamiques, par le biais de l’utilisation d’une caméra IR haute cadence (Telops FAST M3K). L’intérêt de la démarche présentée est double. Suivant un large spectre de vitesses de déformation, l’objectif est d’étudier l’évolution de la densité et de la dissipation calorifique du phénomène de fissuration transverse en fonction de l’augmentation de la vitesse de sollicitation et de l’épaisseur des échantillons. Le matériau de l’étude est un composite stratifié croisé carbone epoxy T700/M21 pour lequel l’influence de l’épaisseur sur la sensibilité à la vitesse est étudiée en faisant varier la séquence d’empilement ([0/90]s, [0/902]s et [0/903]s). L’ensemble des essais est réalisé à l’aide d’un vérin servohydraulique, sur des échantillons d’une longueur utile définie à 40 mm permettant de solliciter le matériau à des vitesses de déformation situées entre = 10-3 s-1et 101 s-1. Afin de minimiser la résolution spatiale et de maximiser la fréquence d’acquisition pour les hautes vitesses, le suivi de l’apparition du phénomène de fissuration transverse est réalisé uniquement suivant la tranche des échantillons testés. L’hypothèse associée à l’instantanéité de la propagation de fissure au travers de l’échantillon a pour cela été vérifiée à l’aide d’une méthode quantitative de suivi de la température suivant la largeur des éprouvettes (Figure 1(a)). Les premières tendances expérimentales préfigurent d’une relative insensibilité à la vitesse de la densité et de la cinétique de fissuration dans la gamme des basses vitesses pour la configuration [0/903]s(Figure 1(b)). Les analyses sont en cours de réalisation concernant les plus hautes vitesses et les différentes stratifications

Une démarche préliminaire vers une caractérisation fiable en dynamique. "Application à un composite thermoplastique"

De nombreuses études sur les matériaux composites à matrice organique, en particulier thermoplastique, ont montré que le comportement mécanique de tels matériaux est sensible à la vitesse de sollicitation. Cependant, il n’existe pas de consensus permettant de définir les moyens de caractériser, comparer et modéliser ce genre de comportement. Cette étude se focalise sur une démarche expérimentale visant à caractériser de manière robuste le comportement mécanique d’un composite à matrice polyamide 6,6 renforcé de fibres de verre tissées. Une large gamme de vitesses de déformation est étudiée (de ε=10-4 s-1 à ε=102 s-1), à l’aide d’une machine de traction conventionnelle et d’une machine de traction à vitesses rapides. En regard des précautions qu’imposent les essais dynamiques, une investigation portant sur l’optimisation d’une géométrie d’éprouvette a été réalisée. Cette dernière assure la cohérence de l’identification des propriétés macroscopiques, ainsi que le respect de critères émanant de la littérature concernant les effets de forme et les phénomènes de propagation d’ondes de choc. Dans un second temps, afin de minimiser les oscillations dues au montage, un atténuateur d’ondes volumiques a été étudié à l’aide d’une simulation dynamique du montage d’essais. Les résultats révèlent une diminution de l’amplitude des oscillations de la force mesurée et une meilleure homogénéité des déformations dans la zone utile de l’éprouvette. Il en résulte une procédure robuste permettant d’aboutir à des données fiables et donc exploitables pour identifier un modèle