Decreased myoblast differentiation in chronic binge alcohol-administered simian immunodeficiency virus-infected male macaques: role of decreased miR-206

Skeletal muscle stem cells play a critical role in regeneration of myofibers. We previously demonstrated that chronic binge alcohol (CBA) markedly attenuates myoblast differentiation potential and myogenic gene expression. Muscle-specific microRNAs (miRs) are implicated in regulation of myogenic genes. The aim of this study was to determine whether myoblasts isolated from asymptomatic CBA-administered simian immunodeficiency virus (SIV)-infected macaques treated with antiretroviral therapy (ART) showed similar impairments and, if so, to elucidate potential underlying mechanisms. Myoblasts were isolated from muscle at 11 mo after SIV infection from CBA/SIV macaques and from time-matched sucrose (SUC)-treated SIV-infected (SUC/SIV) animals and age-matched controls. Myoblast differentiation and myogenic gene expression were significantly decreased in myoblasts from SUC/SIV and CBA/SIV animals compared with controls. SIV and CBA decreased muscle-specific miR-206 in plasma and muscle and SIV decreased miR-206 expression in myoblasts, with no statistically significant changes in other muscle-specific miRs. These findings were associated with a significant increase in histone deacetylase 4 (HDAC4) and decrease in myogenic enhancer factor 2C (MEF2C) expression in CBA/SIV muscle. Transfection with miR-206 inhibitor decreased myotube differentiation, increased expression of HDAC4, and decreased MEF2C, suggesting a critical role of miR-206 in myogenesis. Moreover, HDAC4 was confirmed to be a direct miR-206 target. These results support a mechanistic role for decreased miR-206 in suppression of myoblast differentiation resulting from chronic alcohol and SIV infection. The parallel changes in skeletal muscle and circulating levels of miR-206 warrant studies to establish the possible use of plasma miR-206 as an indicator of impaired muscle function.

Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene

Based on a low-temperature scanning tunneling microscopy study, we present a direct visualization of a cycloaddition reaction performed for some specific fluorinated maleimide molecules deposited on graphene. Up to now, it was widely admitted that such a cycloaddition reaction can not happen without pre-existing defects. However, our study shows that the cycloaddition reaction can be carried out on a defect-free basal graphene plane at room temperature. In the course of covalently grafting the molecules to graphene, the sp² conjugation of carbon atoms was broken, and local sp³ bonds were created. The grafted molecules perturbed the graphene lattice, generating a standing-wave pattern with an anisotropy which was attributed to a (1,2) cycloaddition, as revealed by T-matrix approximation calculations. DFT calculations showed that while both (1,4) and (1,2) cycloadditions were possible on free-standing graphene, only the (1,2) cycloaddition could be obtained for graphene on SiC(0001). Globally averaging spectroscopic techniques, XPS and ARPES, were used to determine the modification in the elemental composition of the samples induced by the reaction, indicating an opening of an electronic gap in graphene.

Low loss optical waveguiding in large single crystals of a thiophene-based oligomer

Active optical waveguides based on functional small organic molecules in micro/nano regime have attracted great interest for their potential applications in high speed miniaturized photonic integrations.

High-precision (34) S/(32) S measurements in vertebrate bioapatites using purge-and-trap elemental analyser/isotope ratio mass spectrometry technology

RATIONALE

In ecological studies, the sulfur isotope compositions (δ(34) S values) of soft tissues (e.g. hair, skin, nail, muscle, collagen) allow the determination of both past and present-day living environments of organisms. However, technical limitations have so far prevented reliable sulfur isotope analyses of minerals having low sulfur content, such as bioapatite, which is the crystalline component of skeletal tissues. The development of 'purge-and-trap' technology in elemental analysers recently demonstrated new possibilities to solve some of those technical difficulties.

METHODS

We have used a VarioPYROcube elemental analyser (EA) equipped with 'purge-and-trap' technology, interfaced in continuous flow mode to an Isoprime 100 isotope ratio mass spectrometer, to measure the sulfur isotope compositions of bioapatite samples. We first characterised a working calibrated material of chemical composition close to those of our samples, the low-S bearing phosphorite BCR32, against the two δ(34) SV-CDT reference-calibrated materials, NBS-127 and IAEA-SO-5. We have confirmed a δ(34) SV-CDT value of +18.4‰ (1σ = 0.5; n = 18) in agreement with the previously published value. Using BCR32 as a compositional and isotopic reference material, we have then measured the δ(34) SV-CDT values of various bioapatite tissues (bone, dentine and enamel) from both modern and fossil vertebrates living in different environments (marine, freshwater and terrestrial).

RESULTS

Our results demonstrate the capacity of this analytical setup to measure the δ(34) SV-CDT values of low-S bioapatite samples (0.14 to 1.19 wt%) with a good analytical precision (1σ = 0.5; n = 14). Our results also show that the δ(34) SV-CDT values of modern and fossil vertebrate bioapatites allow discrimination between marine environments and freshwater or terrestrial ones.

CONCLUSIONS

Sulfur isotope analysis of bioapatite has great potential to track the living environment of extinct vertebrates for which only fossilised bones or teeth have been preserved. Copyright © 2016 John Wiley & Sons, Ltd.

The development of a peak-time criterion for designing controlled-release devices

This work consists of estimating dynamic characteristics for topically-applied drugs when the magnitude of the flux increases to a maximum value, called peak flux, before declining to zero. This situation is typical of controlled-released systems with a finite donor or vehicle volume. Laplace transforms were applied to the governing equations and resulted in an expression for the flux in terms of the physical characteristics of the system. After approximating this function by a second-order model, three parameters of this reduced structure captured the essential features of the original process. Closed-form relationships were then developed for the peak flux and time-to-peak based on the empirical representation. Three case studies that involve mechanisms, such as diffusion, partitioning, dissolution and elimination, were selected to illustrate the procedure. The technique performed successfully as shown by the ability of the second-order flux to match the prediction of the original transport equations. A main advantage of the proposed method is that it does not require a solution of the original partial differential equations. Less accurate results were noted for longer lag times.

SoK: Making Sense of Censorship Resistance Systems

An increasing number of countries implement Internet censorship at different scales and for a variety of reasons. Several censorship resistance systems (CRSs) have emerged to help bypass such blocks. The diversity of the censor’s attack landscape has led to an arms race, leading to a dramatic speed of evolution of CRSs. The inherent complexity of CRSs and the breadth of work in this area makes it hard to contextualize the censor’s capabilities and censorship resistance strategies. To address these challenges, we conducted a comprehensive survey of CRSs-deployed tools as well as those discussed in academic literature-to systematize censorship resistance systems by their threat model and corresponding defenses. To this end, we first sketch a comprehensive attack model to set out the censor’s capabilities, coupled with discussion on the scope of censorship, and the dynamics that influence the censor’s decision. Next, we present an evaluation framework to systematize censorship resistance systems by their security, privacy, performance and deployability properties, and show how these systems map to the attack model. We do this for each of the functional phases that we identify for censorship resistance systems: communication establishment, which involves distribution and retrieval of information necessary for a client to join the censorship resistance system; and conversation, where actual exchange of information takes place. Our evaluation leads us to identify gaps in the literature, question the assumptions at play, and explore possible mitigations.

No Evidence That Nitrogen Limitation Influences the Elemental Composition of Isopod Transcriptomes and Proteomes

The field of stoichiogenomics aims at understanding the influence of nutrient limitations on the elemental composition of the genome, transcriptome, and proteome. The 20 amino acids and the 4 nt differ in the number of nutrients they contain, such as nitrogen (N). Thus, N limitation shall theoretically select for changes in the composition of proteins or RNAs through preferential use of N-poor amino acids or nucleotides, which will decrease the N-budget of an organism. While these N-saving mechanisms have been evidenced in microorganisms, they remain controversial in multicellular eukaryotes. In this study, we used 13 surface and subterranean isopod species pairs that face strongly contrasted N limitations, either in terms of quantity or quality. We combined in situ nutrient quantification and transcriptome sequencing to test if N limitation selected for N-savings through changes in the expression and composition of the transcriptome and proteome. No evidence of N-savings was found in the total N-budget of transcriptomes or proteomes or in the average protein N-cost. Nevertheless, subterranean species evolving in N-depleted habitats displayed lower N-usage at their third codon positions. To test if this convergent compositional change was driven by natural selection, we developed a method to detect the strand-asymmetric signature that stoichiogenomic selection should leave in the substitution pattern. No such signature was evidenced, indicating that the observed stoichiogenomic-like patterns were attributable to nonadaptive processes. The absence of stoichiogenomic signal despite strong N limitation within a powerful phylogenetic framework casts doubt on the existence of stoichiogenomic mechanisms in metazoans.

Don’t Interrupt Me While I Type: Inferring Text Entered Through Gesture Typing on Android Keyboards

We present a new side-channel attack against soft keyboards that support gesture typing on Android smartphones. An application without any special permissions can observe the number and timing of the screen hardware interrupts and system-wide software interrupts generated during user input, and analyze this information to make inferences about the text being entered by the user. System-wide information is usually considered less sensitive than app-specific information, but we provide concrete evidence that this may be mistaken. Our attack applies to all Android versions, including Android M where the SELinux policy is tightened.

We present a novel application of a recurrent neural network as our classifier to infer text. We evaluate our attack against the “Google Keyboard” on Nexus 5 phones and use a real-world chat corpus in all our experiments. Our evaluation considers two scenarios. First, we demonstrate that we can correctly detect a set of pre-defined “sentences of interest” (with at least 6 words) with 70% recall and 60% precision. Second, we identify the authors of a set of anonymous messages posted on a messaging board. We find that even if the messages contain the same number of words, we correctly re-identify the author more than 97% of the time for a set of up to 35 sentences.

Our study demonstrates a new way in which system-wide resources can be a threat to user privacy. We investigate the effect of rate limiting as a countermeasure but find that determining a proper rate is error-prone and fails in subtle cases. We conclude that real-time interrupt information should be made inaccessible, perhaps via a tighter SELinux policy in the next Android version.

[Clozapine rechallenge after neutropenia in resistant schizophrenia: A review]

INTRODUCTION

Clozapine is an atypical antipsychotic known for its efficacy in refractory schizophrenia. One of the adverse effects is neutropenia. This dysplasia is a rare but major side effect which leads to a discontinuation and constitutes further contraindication. Thereafter, therapeutic options decrease dramatically. Mechanisms involved are not well known at this time and can be combined. A toxic hypothesis may be more likely than an immune-allergic one.

METHODS

We have reviewed publications on Medline describing procedures that allowed clozapine rechallenge after blood dyscrasia in refractory schizophrenia. Three different procedures were found: simple rechallenge, rechallenge with lithium and rechallenge with Granulocyte - colony stimulating factor (G-CSF). Rechallenge could be simple or multiple.

RESULTS

These past years, clozapine have been rechallenged successfully after neutropenia thanks to different procedures, the different options being simple rechallenge, rechallenge with lithium and/or rechallenge with G-CSF. Lithium as G-CSF are used to increase neutrophil blood rate and prevent neutropenia recurrence after clozapine rechallenge. G-CSF was first used within the context of chemotherapy and extends now to clozapine-induced neutropenia. Both for lithium and G-CSF, numerous procedures are reviewed and cannot be compared.

DISCUSSION

Publications are limited but increasing, and they point out that a careful rechallenge can be successful. However, interesting data can be extracted. First, clozapine is more likely to be incriminated in neutropenia when patients receive many drugs, but a careful study could prevent some discontinuation. Indeed, other drugs or a hematologic disease could be involved. Moreover, several contributing factors have been found such as HLA group and drug interaction. Ethnic origin also affects neutrophil rate. That is why, in Great Britain, a subgroup of patients "benign ethnic neutropenia" has been introduced to enlarge threshold and allow these patients to access clozapine despite lower blood counts. Then, rechallenge choice has to be done on a case-by-case basis and only after considering the benefits and risks of such a treatment. Most of the time, clinical advice of rechallenge arises from the inefficiency of other antipsychotics and even sismotherapy failure. Patients and sometimes families have to be informed and give their consent. Preventive measures have been found such as taking a hematologic recommendation and doing twice-a-week blood sample monitoring. With regards lithium and G-CSF, some efficient doses are assumed (lithium: 0,4-1,1 mEq/L and G-CSF>0,3 mg/week). Lithium as G-CSF may have other adverse effects which need to be considered. There is no successful rechallenge reported after agranulocytosis. Some publications highlight that if neutropenia occurs on rechallenge, it will do so more quickly and more severe than at the time of initial trial of clozapine.

CONCLUSION

There is emerging evidence of successful clozapine rechallenging. However, further investigations are required as randomized controlled trials to reassess guidelines and establish the safety and effectiveness of the different procedures. Because of the practical and ethical difficulties of designing such studies, referral hospitals could be elected, and common background writing proposed in order to ease data comparison.

Site-selective local fluorination of graphene induced by focused ion beam irradiation

The functionalization of graphene remains an important challenge for numerous applications expected by this fascinating material. To keep advantageous properties of graphene after modification or functionalization of its structure, local approaches are a promising road. A novel technique is reported here that allows precise site-selective fluorination of graphene. The basic idea of this approach consists in the local radicalization of graphene by focused ion beam (FIB) irradiation and simultaneous introduction of XeF₂ gas. A systematic series of experiments were carried out to outline the relation between inserted defect creation and the fluorination process. Based on a subsequent X-ray photoelectron spectroscopy (XPS) analysis, a 6-fold increase of the fluorine concentration on graphene under simultaneous irradiation was observed when compared to fluorination under normal conditions. The fluorine atoms are predominately localized at the defects as indicated from scanning tunneling microscopy (STM). The experimental findings are confirmed by density functional theory which predicts a strong increase of the binding energy of fluorine atoms when bound to the defect sites. The developed technique allows for local fluorination of graphene without using resists and has potential to be a general enabler of site-selective functionalization of graphene using a wide range of gases.

Risks for Workers Handling Solid Oral Doses: Development of a Tool to Improve Personal Protection

Handling of pharmaceutical specialities is required before its distribution or administration. Unpackaging and repackaging solid oral doses (SOD) in pharmacy settings; crushing, pills fragmenting or capsules opening inside care units may expose nurses and pharmacy dispensers to chemical contamination according to three recent North American studies. In the absence of a regulatory framework the application of the “principle of precaution” implies at first an analysis of the medication circuit and then the implementation of protective measures to prevent healthcare workers from contamination. Comparison of professional recommendations published in other countries allowed us to select a group of protective methods. We gathered these technical and organisational methods to compose a matrix of recommendations intended to hospital staff involved in SOD handling. This tool aims to improve the development of good manufacturing practices (GMP). It combines the issue of personal protection with other criteria such as quality, efficiency and safety of a medication.

Respective contributions of diet and medium to the bioaccumulation of pharmaceutical compounds in the first levels of an aquatic trophic web

Nowadays, pharmaceuticals (PCs) are ubiquitous in aquatic ecosystems. It is known that these compounds have ecotoxic effects on aquatic organisms at low concentrations. Moreover, some of them can bioaccumulate inside organisms or trophic webs exposed at environmental concentrations and amplify ecotoxic impacts. PCs can bioaccumulate in two ways: exposure to a medium (e.g., respiration, diffusion, etc.) and/or through the dietary route. Here, we try to assess the respective contributions of these two forms of contamination of the first two levels of an aquatic trophic web. We exposed Daphnia magna for 5 days to 0, 5, and 50 μg/L (15)N-tamoxifen and then fed them with control and contaminated diets. We used an isotopic method to measure the tamoxifen content inside the daphnids after several minutes' exposure and every day before and after feeding. We found that tamoxifen is very bioaccumulative inside daphnids (BCF up to 12,000) and that the dietary route has a significant impact on contamination by tamoxifen (BAF up to 22,000), especially at low concentrations in medium.