A new biophysical decompression model for estimating the risk of articular bends during and after decompression

International audienceThe biophysical models that intend to predict the risk of decompression sickness after a change of pressure are not numerous. Few approaches focus in particular on joints as target tissues, with the aim to describe properly the mechanisms inducing pain. Nevertheless, for this type of decompression incidents, called , no model proved to fit the empirical results for a broad range of exposures and decompression procedures. We present here an original biophysical decompression model for describing the occurrence of articular bends. A target joint is broken down into two parts that exchange inert gases with the blood by perfusion and with each other by diffusion over distances of a few millimeters. This diffusion pathway allows the slow amplification of microbubbles growing during and after decompression, consistent with the possible delayed occurrence of bends. The diffusion coefficients introduced into this model are larger than those introduced into most modern decompression models. Their value remains physical (#10m/s). Inert gas exchanges and the formation, amplification and resorption of microbubbles during and after decompression were simulated. We used a critical gas volume criterion for predicting the occurrence of bends. A risk database extracted from COMEX experience and other published studies was used for the correlation of model parameters not known . We considered a large range of exposure, and the commonly used inert gases nitrogen and helium. This correlation phase identified the worst biophysical conformations most likely to lead to the formation, in tissues such as tendons, of a large number of microbubbles recruited from pre-existing gas nuclei during decompression. The risk of bends occurrence was found to be linked to the total separated gas volume generated during and after decompression. A clamping phenomenon occurs soon after the start of decompression, greatly slowing the gas exchanges controlled especially by the oxygen window. This model, which reproduces many empirical findings, may be considered both descriptive and predictive

Effect of n-3 fatty acids on metabolism of apoB100-containing lipoprotein in type 2 diabetic subjects

The effect of long-chain n-3 PUFA on the metabolism of apoB100-containing lipoprotein in diabetic subjects is not fully understood. The objective of the present study was to determine the effect of a daily intake of 1080mg EPA and 720mg DHA for diabetic subjects on the kinetics of apoB100-containing lipoprotein in the fasting state. A kinetic study was undertaken to determine the mechanisms involved in the effects of n-3 fatty acids in terms of a decrease in triacylglycerol level in type 2 diabetic patients. We have studied the effect of fish oils on the metabolism of apoB100 endogenously labelled by [5,5,5-2H3]-leucine in type 2 diabetic patients in the fasting state. The kinetic parameters of apoB100 in VLDL, intermediate-density lipoprotein and LDL were determined by compartmental modelling in five diabetic subjects before and 8 weeks aftern-3 fatty acid treatment. Treatment did not change the plasma cholesterol level (0·801 (sd 0·120)v. 0·793 (sd 0·163) mmol/l) but lowered the plasma triacylglycerol level (1·776 (sd 0·280) v.1·356 (sd 0·595) mmol/l; p<0·05). Treated patients showed a decrease in VLDL apoB100 concentration (0·366 (sd 0·030) v.0·174 (sd 0·036) g/l; v<0·05) related to a decrease in VLDL 1 production (1·49 (sd 0·23) v.0·44 (sd 0·19) mg/kg per h; p<0·05) and an increase in the VLDL conversion rate (0·031 (sd 0·024)v.0·052 (sd 0·040) per h; p<0·05), with no change in fractional catabolic rates. Treatment led to a higher direct production of intermediate-density lipoprotein (0·02 (sd 0·01) v 0·24 (sd 0·12) mg/kg per h; p<0·05). In conclusion, the present study, conducted in the fasting state, showed that supplementation with n-3 fatty acids in type 2 diabetic patients induced beneficial changes in the metabolism of apoB100-containing lipoprotei

A purple plaque in a patient with systemic sclerosis

We present the case of a 43-year old woman with anti-U3 ribonucleoprotein antibody-positive systemic sclerosis presenting with an enlarging purple plaque on the left upper arm. The skin was not sclerotic; however, there had been a cluster of long-standing telangiectases preceding the plaque. Histology and immunohistochemistry confirmed an angiosarcoma. There are five reported cases in the literature about angiosarcoma arising in the skin of patients with systemic sclerosis; however, to our knowledge, this is the first to have arisen from non-sclerotic skin. We would urge clinicians to adopt a high index of suspicion for atypical vascular tumours presenting in patients with systemic sclerosis

Potentially inappropriate medication use among patients with Alzheimer disease in the REAL.FR cohort: be aware of atropinic and benzodiazepine drugs!

Abstract Objective Few studies have investigated potentially inappropriate medication (PIM) use in patients with Alzheimer&apos;s disease (AD). The aim of our study was to assess the prevalence of PIM in community-dwelling patients diagnosed with mild-to-moderate AD and identify the clinical factors associated with PIM prescriptions. Methods REAL.FR is a 4-year, prospective, multicenter French cohort of AD patients recruited in centers of expertise. We analyzed patient baseline data at entry into the study. PIMs were assessed using the Laroche list. A multivariate logistic regression was conducted to assess factors associated with PIMs. Results A total of 684 AD patients were enrolled in the study [mean age 77.9±6.8 years, 486 (71.0 %) females]. According to the Laroche list, 46.8 % [95 % confidence interval (CI) 43.0-50.5 %] of the patients had at least one PIM. &quot;Cerebral vasodilators&quot; were the most widely used class of PIM, accounting for 24.0 % (95 % CI 20.9-27.3 %) of all prescriptions, followed by atropinic drugs (17.0 %, 95 % CI 14.1-19.8 %) and long half-life benzodiazepines (8.5 %, 95 % CI 6.4-10.6 %). Atropinic drugs were associated with cholinesterase inhibitors in 16 % of patients. In the multivariate analysis, only two factors, namely, female gender [odds ratio (OR) 1.5, 95 % CI 1.1-2.2] and polypharmacy (≥5 drugs; OR3.6, 95 % CI 2.6-4.5) were associated with prescriptions for PIMs. Conclusions These results reveal that approximately one out of two community-dwelling patients with mild-to-moderate AD treated by AD specialists use PIMs. They also indicate that the characteristics of the disease and the pharmacodynamic/ pharmacokinetic profile of the drugs prescribed are not sufficiently taken into account by physicians when prescribing for AD patients

Catalytic asymmetric synthesis of the alkaloid (+)-myrtine

A new protocol for the asymmetric synthesis of trans-2,6-disubstituted-4-piperidones has been developed using a catalytic enantioselective conjugate addition reaction in combination with a diastereoselective lithiation–substitution sequence; an efficient synthesis of (+)-myrtine has been achieved via this route.

Experience and Challenges from Clinical Trials with Malaria Vaccines in Africa.

Malaria vaccines are considered amongst the most important modalities for potential elimination of malaria disease and transmission. Research and development in this field has been an area of intense effort by many groups over the last few decades. Despite this, there is currently no licensed malaria vaccine. Researchers, clinical trialists and vaccine developers have been working on many approached to make malaria vaccine available.African research institutions have developed and demonstrated a great capacity to undertake clinical trials in accordance to the International Conference on Harmonization-Good Clinical Practice (ICH-GCP) standards in the last decade; particularly in the field of malaria vaccines and anti-malarial drugs. This capacity is a result of networking among African scientists in collaboration with other partners; this has traversed both clinical trials and malaria control programmes as part of the Global Malaria Action Plan (GMAP). GMAP outlined and support global strategies toward the elimination and eradication of malaria in many areas, translating in reduction in public health burden, especially for African children. In the sub-Saharan region the capacity to undertake more clinical trials remains small in comparison to the actual need.However, sustainability of the already developed capacity is essential and crucial for the evaluation of different interventions and diagnostic tools/strategies for other diseases like TB, HIV, neglected tropical diseases and non-communicable diseases. There is urgent need for innovative mechanisms for the sustainability and expansion of the capacity in clinical trials in sub-Saharan Africa as the catalyst for health improvement and maintained

New Speakers and Language Revitalisation: Arpitan and Community (Re)formation

Today, it is uncontroversial to claim that France’s regional (minority) languages (RLs) are in decline. However, revitalisation movements have nonetheless continued to surface, and this chapter considers one by-product of such efforts: the emergence of new speakers in RL contexts. The term ‘new speaker’ refers to individuals who acquire the target language not through traditional transmission contexts (e.g. home, family), but instead as adults through language revitalisation initiatives. The chapter focuses on revitalisation efforts in the context of Francoprovençal, a severely endangered and understudied RL spoken transnationally across French, Italian and Swiss borders. A critical examination of current studies supplemented with recently collected empirical data shows new speakers to be central agents in a movement championing proto-nation-statehood across national borders, reorienting the region’s traditional sociolinguistic field

Determinants of synaptic integration and heterogeneity in rebound firing explored with data-driven models of deep cerebellar nucleus cells

Significant inroads have been made to understand cerebellar cortical processing but neural coding at the output stage of the cerebellum in the deep cerebellar nuclei (DCN) remains poorly understood. The DCN are unlikely to just present a relay nucleus because Purkinje cell inhibition has to be turned into an excitatory output signal, and DCN neurons exhibit complex intrinsic properties. In particular, DCN neurons exhibit a range of rebound spiking properties following hyperpolarizing current injection, raising the question how this could contribute to signal processing in behaving animals. Computer modeling presents an ideal tool to investigate how intrinsic voltage-gated conductances in DCN neurons could generate the heterogeneous firing behavior observed, and what input conditions could result in rebound responses. To enable such an investigation we built a compartmental DCN neuron model with a full dendritic morphology and appropriate active conductances. We generated a good match of our simulations with DCN current clamp data we recorded in acute slices, including the heterogeneity in the rebound responses. We then examined how inhibitory and excitatory synaptic input interacted with these intrinsic conductances to control DCN firing. We found that the output spiking of the model reflected the ongoing balance of excitatory and inhibitory input rates and that changing the level of inhibition performed an additive operation. Rebound firing following strong Purkinje cell input bursts was also possible, but only if the chloride reversal potential was more negative than −70 mV to allow de-inactivation of rebound currents. Fast rebound bursts due to T-type calcium current and slow rebounds due to persistent sodium current could be differentially regulated by synaptic input, and the pattern of these rebounds was further influenced by HCN current. Our findings suggest that active properties of DCN neurons could play a crucial role for signal processing in the cerebellum

Photodegradation of polystyrene/montmorillonite clay: the effect of the type of clay and presence of salt

Compósitos de poliestireno/montmorilonita (PS/MMT) contendo 2,5% em peso de argila foram preparados com dois tipos de argila modificada com sais quaternários de amônio. Também foram preparadas amostras do PS + sal quaternário de amônio, utilizando-se proporção de sal semelhante à usada na modificação da argila. Todas as amostras foram expostas à radiação UV por períodos de até 12 semanas, e em seguida foram realizados testes para avaliar as modificações em massa molar, propriedades mecânicas (tração e impacto), estrutura química (FTIR) e superfície de fratura (MEV) dessas amostras. Os resultados mostraram que compostos metálicos existentes na argila catalisam o processo fotodegradativo do PS e a presença isolada do sal não altera significativamente o comportamento do PS frente à radiação UV