302 research outputs found

    Analyse van klachten na sterilisatie met Essure® in Nederland : Gezondheidsproblemen na een niet chirurgische sterilisatie-ingreep bij vrouwen

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    alleen digitaal verschenenHet RIVM heeft klachten geanalyseerd van vrouwen die zijn gesteriliseerd met Essure®. Dit zijn metalen veertjes die via de baarmoeder in beide eileiders worden gebracht waardoor deze na ongeveer 3 maanden dichtgroeien. Het voordeel van deze sterilisatiemethode is, in vergelijking met de traditionele afsluiting van de eileiders, dat er geen chirurgische ingreep voor nodig is. Het aantal gemelde klachten komt van ruim 1,5 procent van de circa 30.000 vrouwen die in Nederland met Essure® zijn behandeld. De meest genoemde klachten zijn pijn en vermoeidheid. Bij de pijnklachten gaat het vooral om de buik, de rug en het hoofd. Daarnaast worden hevige bloedingen tijdens en tussen de menstruatie, stemmingswisselingen, geheugenverlies en concentratieproblemen gemeld. Het werkelijke aantal vrouwen met klachten is onbekend. Veel vrouwen geven aan dat deze klachten hun dagelijks leven negatief beïnvloeden. Ze voelen de veertjes zitten of ervaren beperkingen bij het bewegen. Verder kunnen ze de dagelijkse taken en de zorg voor kinderen vaak minder goed uitvoeren. Er zijn ook vrouwen die aangeven dat hun relatie lijdt onder de ontstane problemen. Bij 16 procent van de vrouwen die klachten gemeld hebben, is Essure® verwijderd naar aanleiding van de klachten. 38 procent van de vrouwen in dit onderzoek heeft een afspraak gemaakt om dat te laten doen. De klachten zijn gemeld nadat hieraan via diverse kanalen aandacht is besteed. De Nederlandse Vereniging voor Obstetrie en Gynaecologie (NVOG) heeft de resultaten van de analyse medisch geduid. Sommige klachten zijn mogelijk toe te wijzen aan de plaatsing van Essure®, zoals bepaalde pijnklachten. Bij andere klachten is het moeilijker om een direct verband te leggen omdat er ook andere zaken van invloed kunnen zijn, zoals stoppen met de pil waardoor menstruatieklachten kunnen verergeren. Daarnaast komen verschillende klachten, bijvoorbeeld gewichtsschommelingen en urinewegproblemen, ook met enige regelmaat voor bij vrouwen die geen Essure® hebben. De gemelde klachten komen van vrouwen die tussen 2001 en 2016 het implantaat hebben gekregen. Hun gemiddelde leeftijd was 37 jaar op het moment van de sterilisatie.The RIVM has analyzed the complaints reported by women sterilized using Essure®. Essure® is a sterilization method where two metal coils are placed into both fallopian tubes through the cervix and uterus, provoking those to become blocked after approximately 3 months. In comparison with the traditional sterilization methods, the advantage of the Essure® method is that no surgical procedure is required. The complaints that were received came from more than1,5 percent of the 30.000 women who are estimated to have been sterilized using Essure® in the Netherlands. Probably not all women with health problems have submitted a complaint; therefore, the actual number of women with health problems is unknown. The most frequently mentioned health problems are pain and tiredness. The pain is reported to be located mainly in the abdomen, back, and head. In addition, heavy bleeding during and between menstruations, mood swings, memory loss and concentration problems are also reported frequently. Many women indicated that these health problems negatively affect their daily life. They feel the coils in their body and often experience limitations when moving. They are often less able to adequately perform their daily tasks and take care of their children.There are also women that indicated that their relationship was negatively affected by the health problems. In 16 percent of the women in this study, Essure® has been removed because of the health problems and 38 percent of the women have made an appointment to have Essure® removed. The complaints were submitted, among other reasons, because the media attention on problems experienced by women following sterilization using Essure®. The Dutch Society of Obstetrics and Gyneacology (NVOG) contributed to the interpretation of the results from this study. Some health problems can be directly related to Essure®, for instance some kinds of pain. For other health problems it is more difficult to establish a direct link, because other factors may influence the health problems as well. For instance, heavier menstruation may also be explained by the fact that women stopped taking oral contraceptives following sterilization using Essure®.Furthermore, there are other health problems such as weight changes and urinary tract problems that are also regularly experienced by women not sterilized with Essure®. Women that submitted a complaint were sterilized using Essure between 2001 and 2016. Their mean age at implantation was 37 years.Dutch Health Care Inspectorat

    Crystallization of poly(lactic acid) nucleated with the sorbitol TBPMN

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    We report on the crystallization of poly(lactic acid) (PLA) films in the presence of a sorbitol-based nucleating agent; 1,2,3-tridesoxy-4,6:5,7-bis-O-[(4-propylphenyl) methylene]-nonitol (TBPMN). Dispersion of the nucleating agent was performed by solution-mixing and melt-blending. Crystallization behavior was studied by differential scanning calorimetry (DSC). The structure and morphology were characterized by wide-angle X-ray scattering (WAXS), optical imaging, and atomic force microscopy (AFM). A significant impact of the nucleating agent was observed at or above a threshold concentration of 2 wt%, which was assigned to the solubility limit of TBPMN. The degree of crystallinity reached up to 39.6 % with 2 wt% TBPMN. An influence of the dispersion method was observed on the peak temperature of crystallization (Tcp). While Tcp decreased slightly for solution-mixed films, a sigmoidal trend was noted for melt-blended samples. Under isothermal conditions at 100 °C, the crystallization half-time was lowered from 6.5 min to 1.0 min. Avrami analysis pointed to the formation of 2-dimensional or 3-dimensional crystalline domains; WAXS data revealed α- and α'-crystals, depending on the dispersing method. AFM imaging showed a nanosized fibrillar network of the nucleator within the PLA matrix, demonstrating that TBPMN acted as a soluble self-assembly nucleator.</p

    Mechanics of epithelial tissue formation

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    A key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of randomly placed cells on the surface of the egg. We present a model for generating such a tissue, based on mechanical interactions between the cells, and find that the resulting cellular pattern corresponds to the Voronoi tessellation of the nuclei of the cells. Experimentally, we obtain the same result in both fruit flies and flour beetles, with a distribution of cell shapes that matches that of the model, without any adjustable parameters. Finally, we show that this pattern is broken when the cells grow at different rates.Animal science

    Modeling focal epileptic activity in the Wilson-Cowan model with depolarization block

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    Measurements of neuronal signals during human seizure activity and evoked epileptic activity in experimental models suggest that, in these pathological states, the individual nerve cells experience an activity driven depolarization block, i.e. they saturate. We examined the effect of such a saturation in the Wilson–Cowan formalism by adapting the nonlinear activation function; we substituted the commonly applied sigmoid for a Gaussian function. We discuss experimental recordings during a seizure that support this substitution. Next we perform a bifurcation analysis on the Wilson–Cowan model with a Gaussian activation function. The main effect is an additional stable equilibrium with high excitatory and low inhibitory activity. Analysis of coupled local networks then shows that such high activity can stay localized or spread. Specifically, in a spatial continuum we show a wavefront with inhibition leading followed by excitatory activity. We relate our model simulations to observations of spreading activity during seizures

    Emergent Oscillations in Networks of Stochastic Spiking Neurons

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    Networks of neurons produce diverse patterns of oscillations, arising from the network's global properties, the propensity of individual neurons to oscillate, or a mixture of the two. Here we describe noisy limit cycles and quasi-cycles, two related mechanisms underlying emergent oscillations in neuronal networks whose individual components, stochastic spiking neurons, do not themselves oscillate. Both mechanisms are shown to produce gamma band oscillations at the population level while individual neurons fire at a rate much lower than the population frequency. Spike trains in a network undergoing noisy limit cycles display a preferred period which is not found in the case of quasi-cycles, due to the even faster decay of phase information in quasi-cycles. These oscillations persist in sparsely connected networks, and variation of the network's connectivity results in variation of the oscillation frequency. A network of such neurons behaves as a stochastic perturbation of the deterministic Wilson-Cowan equations, and the network undergoes noisy limit cycles or quasi-cycles depending on whether these have limit cycles or a weakly stable focus. These mechanisms provide a new perspective on the emergence of rhythmic firing in neural networks, showing the coexistence of population-level oscillations with very irregular individual spike trains in a simple and general framework
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