Co-construct, implement and evaluate a multi-level intervention to prevent a sedentary lifestyle in children-Study protocol of the CIPRES study.

BACKGROUND: A sedentary lifestyle is commonly associated with a higher risk of chronic disease development. Among school-aged children from European countries, screen-time represents a significant portion of sedentary time with 39.8% of children spending more than 2h/day in front of a screen on average. Therefore, effective solutions to reduce sedentary behavior (SB) must be found. Multilevel interventions based on the socio-ecological model (SEM) are particularly relevant to take into account influences of the social environment on individuals' SB. Moreover, the trans-contextual model (TCM) can offer complementary levers for individuals' behavior change. The CIPRES study is a theory-based multilevel intervention designed to decrease the SB in French primary school children aged 8-10 years. The present paper describes the protocol of a randomized controlled study to evaluate the effectiveness of the CIPRES multilevel intervention on SB. METHODS: The CIPRES study is a cluster-randomized controlled trial comparing intervention vs control groups. A total of 700 children are targeted for inclusion, distributed in four municipalities considered as clusters. The study consists of two successive phases: 1) co-building of a SB prevention intervention by using a participatory approach involving representatives of each level of the SEM (e.g., children, parents, staff from municipalities, teachers) and 2) implementation and evaluation of the intervention. The intervention will last for 6 weeks in each involved class. Primary outcome will be the sedentary time of children per week, assessed by accelerometry. In addition, children and their parents will be asked to fill out questionnaires concerning children's physical activity level, screen time, quality-of-life and variables of the TCM. DISCUSSION: This study will give information on the effectiveness of a theory-based intervention, involving multiple levels of actors in the co-construction and the implementation of the intervention, that may interest schools and public health officers looking for innovative sedentary prevention programs.

Wound-healing plasticity enables clonal expansion of founder progenitor cells in colitis.

Chronic colonic injury and inflammation pose high risks for field cancerization, wherein injury-associated mutations promote stem cell fitness and gradual clonal expansion. However, the long-term stability of some colitis-associated mutational fields could suggest alternate origins. Here, studies of acute murine colitis reveal a punctuated mechanism of massive, neutral clonal expansion during normal wound healing. Through three-dimensional (3D) imaging, quantitative fate mapping, and single-cell transcriptomics, we show that epithelial wound repair begins with the loss of structural constraints on regeneration, forming fused labyrinthine channels containing epithelial cells reprogrammed to a non-proliferative plastic state. A small but highly proliferative set of epithelial founder progenitor cells (FPCs) subsequently emerges and undergoes extensive cell division, enabling fluid-like lineage mixing and spreading across the colonic surface. Crypt budding restores the glandular organization, imprinting the pattern of clonal expansion. The emergence and functions of FPCs within a critical window of plasticity represent regenerative targets with implications for preneoplasia.

Effectiveness of multilevel interventions based on socio-ecological model to decrease sedentary time in children: a systematic review of controlled studies.

Objectives: Preventive actions of sedentary behavior (SB) based on the socio-ecological model are needed among children and young adolescents. The aim of this systematic review is to ascertain the effectiveness of multilevel interventions (i.e., involving consideration of at least two interventional levels) in reducing sedentary time (ST) in children aged 5-12 years. Methods: Adhering to PRISMA guidelines, a systematic literature search was conducted in three databases (PsyInfo, PubMed and ERIC) until July 2021. Results: 30 trials met the eligibility criteria and were included. They showed acceptable (< 8, n = 18) and high (≥ 8, n = 12) methodological quality. Among studies targeting 2 (n = 2), 3 (n = 19) and 4 levels (n = 9), 1 (50%), 9 (47%) and 7 (78%) were effective and reported significant reduction of ST, respectively. Conclusion: Interventions tend to be more effective when they involve 4 levels, using both agentic and structural strategies (targeting intrinsic determinants, in the organizational environment of the child). Findings underline the relevance of multilevel strategies to reduce ST in children, but also raise issues about operationalization of the socio-ecological perspective. Systematic review registration: PROSPERO, identifier: CRD42020209653.

Particle size distribution in the evaluation of the inhalation toxicity of cosmetic spray products.

While applying cosmetic sprays (pump sprays and propellant-based sprays) intended for use on the skin or hair, consumers may unintentionally inhale sprayed droplets/particles. Thus, it is essential to analyze the size distribution of sprayed droplets/particles because those less than 10 µm are considered to be respirable and may present a high systemic and local exposure risk. In this study, we investigated the droplet/particle size distribution of 78 cosmetic sprays by laser diffraction. Our results showed that the level of respirable droplets/particles released by pump sprays averaged 0.5% of all particles measured (0.00%-2.23%) and that released by propellant-based sprays averaged 15.25% (0.15%-32.27%). Dry shampoos (powder) released the highest percentage of respirable droplets/particles (16.66%-32.27%). A default value of 25% of respirable droplets/particles can also be suggested for dry shampoos. Droplet/particle size distribution was influenced by the spray dispensing system (pump or propellant-based), the product type (hairspray, sunscreen, etc.) and the galenic form (powder, oil, emulsion, etc.). However, it should be noted that more confidence is placed in the pump spray data due to the larger sample size. This study provides data on droplet/particle size, which may be used in a modelling approach to predict inhalation exposure. Therefore, it must be known and used, together with assessments of intrinsic and local toxicities to determine the margin of safety of the product by inhalation route, and to assess the risk of cosmetic sprays.

Organizational innovation under constraints: The case of covid patients' flow management in Parisian hospitals.

The COVID crisis has put hospitals under great stress over the past 2 years and some institutions came close to their breaking points. This has often forced decision makers and the entire institutions to change their practices and the organization of the hospitals in order to continue operating despite limited resources. It has also led some hospitals to develop and implement organizational innovations. This article is based on a qualitative case study analyzing the case of a crisis unit that has implemented various innovative medical and organizational actions in order to manage the flow of resuscitation Covid patients in a large group of hospitals in Paris. This team has implemented a new evaluation scale of resuscitation needs in order to better manage quantitatively and qualitatively the patients' flow; it has defined medical criteria to select the patients eligible for transfer; it has organized one hundred patients transfers to other hospitals' intensive care units, in and out of the region, involving private hospitals and private ambulances for a new collaboration. The case allows us to understand innovation in the midst of an extreme situation, when material and human resources are highly constrained, and with very strong time pressure. We highlight the importance of implementing flexible organizational processes and staffing the crisis team with physicians and nurses with specific and complementary skills and experience in flow management and crisis situations.

Transitional Anal Cells Mediate Colonic Re-epithelialization in Colitis.

BACKGROUND & AIMS: Epithelial wound healing is compromised and represents an unleveraged therapeutic target in inflammatory bowel disease (IBD). Intestinal epithelial cells exhibit plasticity that facilitates dedifferentiation and repair during the response to injury. However, it is not known whether epithelial cells of a neighboring organ can be activated to mediate re-epithelialization in acute colitis. Histological findings of a permanent squamous tissue structure in the distal colon in human IBD could suggest diverse cellular origins of repair-associated epithelium. Here, we tested whether skin-like cells from the anus mediate colonic re-epithelialization in murine colitis. METHODS: We studied dextran sulfate sodium-induced colitis and interleukin 10-deficient colitis in transgenic mice. We performed lineage tracing, 3-dimensional (3D) imaging, single-cell transcriptomics, and biophysical modeling to map squamous cell fates and to identify squamous cell types involved in colonic repair. RESULTS: In acute and chronic colitis, we found a large squamous epithelium, called squamous neo-epithelium of the colon (SNEC), near the anorectal junction. Neighboring squamous cells of the anus rapidly migrate into the ulcerated colon and establish this permanent epithelium of crypt-like morphology. These squamous cells derive from a small unique transition zone, distal to the border of colonic and anal epithelium, that resists colitic injury. The cells of this zone have a pre-loaded program of colonic differentiation and further upregulate key aspects of colonic epithelium during repair. CONCLUSION: Transitional anal cells represent unique reserve cells capable of rebuilding epithelial structures in the colon after colitis. Further study of these cells could reveal novel approaches to direct mucosal healing in inflammation and disease.

Persistence of Lgr5+ colonic epithelial stem cells in mouse models of inflammatory bowel disease.

Intestinal mucosal healing is the primary therapeutic goal of medical treatments for inflammatory bowel disease (IBD). Epithelial stem cells are key players in the healing process. Lgr5+ stem cells maintain cellular turnover during homeostasis in the colonic crypt. However, they are lost and dispensable for repair in a wide variety of injury models, including dextran sulfate sodium (DSS) colitis, radiation, helminth infection, and T-cell activation. The direct loss of Lgr5+ cells activates a plasticity response in the epithelium in which other cell types can serve as stem cells. Whether this paradigm applies to mouse models of IBD remains unknown. In contrast to previously tested models, IBD models involve an inflammatory response rooted in the loss of immunologic tolerance to intestinal luminal contents including the microbiome. Here, we show the persistence of Lgr5+ cells in oxazolone, 2,4,6-trinitrobenzene sulfonic acid (TNBS), and Il10-/-, and Il10-/- Tnfr1-/- IBD models. This contrasts with results obtained from DSS-induced injury. Through high-throughput expression profiling, we find that these colitis models were associated with distinct patterns of cytokine expression. Direct exposure of colonic epithelial organoids to DSS, oxazolone, or TNBS resulted in increased apoptosis and loss of Lgr5+ cells. Targeted ablation of Lgr5+ cells resulted in severe exacerbation of chronic, antibody-induced IL-10-deficient colitis, but had only modest effects in TNBS-induced colitis. These results show that distinct mouse models of IBD-like colitis induce different patterns of Lgr5+ stem cell retention and function.NEW & NOTEWORTHY Acute intestinal injury and epithelial repair are associated with the loss of fast-cycling Lgr5+ stem cells and plasticity in the activation of formerly quiescent cell populations. In contrast, here we show in murine inflammatory bowel disease the persistence of the Lgr5+ stem cell population and its essential role in restricting the severity of chronic colitis. This demonstrates a diversity of stem cell responses to colitis.

Comparing accuracy of lipoarabinomannan urine tests for diagnosis of pulmonary tuberculosis in children from four African countries: a cross-sectional study.

BACKGROUND: A sensitive and specific non-sputum-based test would be groundbreaking for the diagnosis of childhood tuberculosis. We assessed side by side the diagnostic accuracy of the urine-based lipoarabinomannan assays Fujifilm SILVAMP TB LAM (FujiLAM) and Alere Determine TB LAM Ag (AlereLAM) for detection of childhood tuberculosis. METHODS: In this cross-sectional study, we tested urine samples from children younger than 15 years with presumed pulmonary tuberculosis. Children were consecutively recruited from four dedicated outpatient childhood tuberculosis clinics in The Gambia, Mali, Nigeria, and Tanzania. Biobanked urine samples were thawed and tested using FujiLAM and AlereLAM assays. We measured diagnostic performance against a microbiological reference standard (confirmed tuberculosis) and a composite reference standard (confirmed and unconfirmed tuberculosis). Sensitivity and specificity were estimated with bivariate random-effects meta-analyses. FINDINGS: Between July 1, 2017, and Dec 1, 2018, we obtained and stored urine samples from 415 children. 63 (15%) children had confirmed tuberculosis, 113 (27%) had unconfirmed tuberculosis, and 239 (58%) were unlikely to have tuberculosis. 61 children were HIV-positive (prevalence 15%). Using the microbiological reference standard, the sensitivity of FujiLAM was 64·9% (95% CI 43·7-85·2; positive in 40 of 63 confirmed samples) and the sensitivity of AlereLAM was 30·7% (8·6-61·6; 19 of 63). The specificity of FujiLAM was 83·8% (95% CI 76·5-89·4; negative in 297 of 352 unconfirmed and unlikely samples) and the specificity of AlereLAM was 87·8% (79·0-93·7; 312 of 352). Against the composite reference standard, both assays had decreased sensitivity; the sensitivity of FujiLAM was 32·9% (95% CI 24·6-41·9; positive in 58 of 176 confirmed and unconfirmed samples) and the sensitivity of AlereLAM was 20·2% (12·3-29·4; 36 of 176). The specificity of FujiLAM was 83·3% (95% CI 71·8-91·7; negative in 202 of 239 unlikely samples) and the specificity of AlereLAM was 90·0% (81·6-95·6; 216 of 239). INTERPRETATION: By comparison with AlereLAM, FujiLAM showed higher sensitivity and similar specificity. FujiLAM could potentially add value to the rapid diagnosis of tuberculosis in children. FUNDING: German Federal Ministry of Education and Research, the Global Health Innovative Technology Fund, the UK Research and Innovation Global Challenges Research Fund, and the UK Medical Research Council.

Protection against mycobacterial infection: A case-control study of mycobacterial immune responses in pairs of Gambian children with discordant infection status despite matched TB exposure.

BACKGROUND: Children are particularly susceptible to tuberculosis. However, most children exposed to Mycobacterium tuberculosis are able to control the pathogen without evidence of infection. Correlates of human protective immunity against tuberculosis infection are lacking, and their identification would aid vaccine design. METHODS: We recruited pairs of asymptomatic children with discordant tuberculin skin test status but the same sleeping proximity to the same adult with sputum smear-positive tuberculosis in a matched case-control study in The Gambia. Participants were classified as either Highly TB-Exposed Uninfected or Highly TB-Exposed Infected children. Serial luminescence measurements using an in vitro functional auto-luminescent Bacillus Calmette-Guérin (BCG) whole blood assay quantified the dynamics of host control of mycobacterial growth. Assay supernatants were analysed with a multiplex cytokine assay to measure associated inflammatory responses. FINDINGS: 29 pairs of matched Highly TB-Exposed Uninfected and Highly TB-Exposed Infected children aged 5 to 15 years old were enroled. Samples from Highly TB-Exposed Uninfected children had higher levels of mycobacterial luminescence at 96 hours than Highly TB-Exposed Infected children. Highly TB-Exposed Uninfected children also produced less BCG-specific interferon-γ than Highly TB-Exposed Infected children at 24 hours and at 96 hours. INTERPRETATION: Highly TB-Exposed Uninfected children showed less control of mycobacterial growth compared to Highly TB-Exposed Infected children in a functional assay, whilst cytokine responses mirrored infection status. FUNDING: Clinical Research Training Fellowship funded under UK Medical Research Council/Department for International Development Concordat agreement and part of EDCTP2 programme supported by European Union (MR/K023446/1). Also MRC Program Grants (MR/K007602/1, MR/K011944/1, MC_UP_A900/1122).

A three-marker protein biosignature distinguishes tuberculosis from other respiratory diseases in Gambian children.

BACKGROUND: Our study aimed to identify a host cytokine biosignature that could distinguish childhood tuberculosis (TB) from other respiratory diseases (OD). METHODS: Cytokine responses in prospectively recruited children with symptoms suggestive of TB were measured in whole blood assay supernatants, harvested after overnight incubation, using a Luminex platform. We used logistic regression models with Least Absolute Shrinkage and Selection Operator (LASSO) penalty to identify the optimal biosignature associated with confirmed TB disease in the training set. We subsequently assessed its performance in the test set. FINDINGS: Of the 431 children included in the study, 44 had bacteriologically confirmed TB, 60 had clinically diagnosed TB while 327 had OD. All children were HIV-negative. Application of LASSO regression models to the training set (n = 260) resulted in the combination of IL-1ra, IL-7 and IP-10 from unstimulated samples as the optimally discriminant cytokine biosignature associated with bacteriologically confirmed TB. In the test set (n = 171), this biosignature distinguished children diagnosed with TB disease, irrespective of microbiological confirmation, from OD with area under the receiver operator characteristic curve (AUC) of 0•74 (95% CI: 0•67, 0•81), and demonstrated sensitivity and specificity of 72•2% (95% CI: 60•4, 82•1%) and 75•0% (95% CI: 64•9, 83•4%) respectively, with its performance independent of their age group and their age- and sex-adjusted nutritional status. INTERPRETATION: This novel biosignature of childhood TB derived from unstimulated supernatants is promising. Independent validation with further optimisation will improve its performance and translational potential. FUNDING: Steinberg Fellowship (McGill University); Grand Challenges Canada; MRC Program Grant.

In vitro measurement of skin sensitization hazard of mixtures and finished products: Results obtained with the SENS-IS assays.

Product safety evaluation in the EU is based on data mainly obtained on individual ingredients. However, mixture effects have been demonstrated in numerous skin sensitization studies due to the presence of irritating chemicals or to modification of dermal absorption. To evaluate the ability of the SENS-IS assay to detect such mixture effects, we performed three sets of experiments: First, the importance of the vehicle on absorption of individual ingredients was evaluated by testing the effect of commonly used cosmetic preparations on the sensitizing potential of 3 chemical allergens and 2 fragrance blends. The sensitizing potential of the 3 allergens was significantly reduced when tested in microemulsion while the "cleansing water" preparation significantly increased it. Water in oil, oil in water or oil preparations had significant but more moderate (enhancing or reducing) effects on the skin sensitization potency of the tested chemicals. We then analyzed the influence of irritants (SDS and Lactic acid) on the sensitizing potency of various allergens. The SENS-IS assay detected an enhancement of the potency of some allergens when mixed with non-irritating concentrations of irritant chemicals. We also tested the influence of mixing different sensitizers to analyze the effect of mixtures on the sensitization threshold. Some mixtures of chemicals, at doses that did not induce a positive signal in the SENS-IS assay alone, became positive, indicating a mixture effect. Finally we tested commercially available finished cosmetic products to find out that they were not all negative. These results indicate that the SENS-IS assay is a valuable source of information when analyzing mixture component effects and finished products.

Keys to successful implementation of a French national quality indicator in health care organizations: a qualitative study.

BACKGROUND: Several countries have launched public reporting systems based on quality indicators (QIs) to increase transparency and improve quality in health care organizations (HCOs). However, a prerequisite to quality improvement is successful local QI implementation. The aim of this study was to explore the pathway through which a mandatory QI of the French national public reporting system, namely the quality of the anesthesia file (QAF), was put into practice. METHOD: Seven ethnographic case studies in French HCOs combining in situ observations and 37 semi-structured interviews. RESULTS: A significant proportion of potential QAF users, such as anesthetists or other health professionals were often unaware of quality data. They were, however, involved in improvement actions to meet the QAF criteria. In fact, three intertwined factors influenced QAF appropriation by anesthesia teams and impacted practice. The first factor was the action of clinical managers (chief anesthetists and head of department) who helped translate public policy into local practice largely by providing legitimacy by highlighting the scientific evidence underlying QAF, achieving consensus among team members, and pointing out the value of QAF as a means of work recognition. The two other factors related to the socio-material context, namely the coherence of information systems and the quality of interpersonal ties within the department. CONCLUSIONS: Public policy tends to focus on the metrological validity of QIs and on ranking methods and overlooks QI implementation. However, effective QI implementation depends on local managerial activity that is often invisible, in interaction with socio-material factors. When developing national quality improvement programs, health authorities might do well to specifically target these clinical managers who act as invaluable mediators. Their key role should be acknowledged and they ought to be provided with adequate resources.

No added value of interferon-γ release to a prediction model for childhood tuberculosis.

The predictive value of a combination of clinical and radiological features with interferon-γ release assay (IGRA) for diagnosis of active tuberculosis (TB) disease among TB-exposed children is unknown.150 symptomatic HIV-negative children (aged 3 months to 14 years), prospectively recruited through active contact tracing, were included. Backward stepwise logistic regression and bootstrapping techniques were used for the development and internal validation of a clinical prediction model for active TB disease. Model discrimination and incremental value of a positive IGRA test were assessed by area under the receiver operating characteristic curve (AUC).35 (23%) children were diagnosed with active TB disease and started on treatment and 115 (77%) had other respiratory tract infections. A final parsimonious clinical model, comprising age <5 years (adjusted (a)OR 4.8, 95% CI 2.0-11.5) and lymphadenopathy on clinical examination (aOR 4.9, 95% CI 1.8-13.0) discriminated active TB disease from other disease with an AUC of 0.70 (95% CI 0.61-0.80). A positive IGRA result did not improve the discriminatory ability of the clinical model (c-statistic 0.72 versus 0.70; p=0.644).A clinical algorithm, including age <5 years and lymphadenopathy classified 70% of active TB disease among symptomatic TB-exposed children. IGRA does not add any discriminatory value to this prediction model.

Enzymatic degradation of Elephant grass (Pennisetum purpureum) stems: influence of the pith and bark in the total hydrolysis.

The internal pith of a high energy plant, Elephant grass (EG), was more extensively degraded (>50% dry matter) compared to the outer cortex (31%) or the whole stem (35%) by an enzyme preparation from Humicola insolens, Ultraflo. Reducing sugars and acetic acid release from the pith was also higher compared to the cortex. Supplementation of Ultraflo with a type-C feruloyl esterase increased the level of deacetylation but also led to reduced solubilisation. The addition of 20% dimethyl sulfoxide (DMSO) as a co-solvent also reduced the solubility of EG by Ultraflo, although acetic acid release was increased, complimenting previous results found on model substrates. The presence of DMSO was also shown to have a protective effect on xylanase activity but not acetyl esterase activity in Ultraflo. Xylan in the biomass was preferentially solubilised by DMSO, while Ultraflo removed more glucose than xylose.

Analysis of host responses to Mycobacterium tuberculosis antigens in a multi-site study of subjects with different TB and HIV infection states in sub-Saharan Africa.

BACKGROUND: Tuberculosis (TB) remains a global health threat with 9 million new cases and 1.4 million deaths per year. In order to develop a protective vaccine, we need to define the antigens expressed by Mycobacterium tuberculosis (Mtb), which are relevant to protective immunity in high-endemic areas. METHODS: We analysed responses to 23 Mtb antigens in a total of 1247 subjects with different HIV and TB status across 5 geographically diverse sites in Africa (South Africa, The Gambia, Ethiopia, Malawi and Uganda). We used a 7-day whole blood assay followed by IFN-γ ELISA on the supernatants. Antigens included PPD, ESAT-6 and Ag85B (dominant antigens) together with novel resuscitation-promoting factors (rpf), reactivation proteins, latency (Mtb DosR regulon-encoded) antigens, starvation-induced antigens and secreted antigens. RESULTS: There was variation between sites in responses to the antigens, presumably due to underlying genetic and environmental differences. When results from all sites were combined, HIV- subjects with active TB showed significantly lower responses compared to both TST(-) and TST(+) contacts to latency antigens (Rv0569, Rv1733, Rv1735, Rv1737) and the rpf Rv0867; whilst responses to ESAT-6/CFP-10 fusion protein (EC), PPD, Rv2029, TB10.3, and TB10.4 were significantly higher in TST(+) contacts (LTBI) compared to TB and TST(-) contacts fewer differences were seen in subjects with HIV co-infection, with responses to the mitogen PHA significantly lower in subjects with active TB compared to those with LTBI and no difference with any antigen. CONCLUSIONS: Our multi-site study design for testing novel Mtb antigens revealed promising antigens for future vaccine development. The IFN-γ ELISA is a cheap and useful tool for screening potential antigenicity in subjects with different ethnic backgrounds and across a spectrum of TB and HIV infection states. Analysis of cytokines other than IFN-γ is currently on-going to determine correlates of protection, which may be useful for vaccine efficacy trials.

New insights into sulfur metabolism in yeasts as revealed by studies of Yarrowia lipolytica.

Yarrowia lipolytica, located at the frontier of hemiascomycetous yeasts and fungi, is an excellent candidate for studies of metabolism evolution. This yeast, widely recognized for its technological applications, in particular produces volatile sulfur compounds (VSCs) that fully contribute to the flavor of smear cheese. We report here a relevant global vision of sulfur metabolism in Y. lipolytica based on a comparison between high- and low-sulfur source supplies (sulfate, methionine, or cystine) by combined approaches (transcriptomics, metabolite profiling, and VSC analysis). The strongest repression of the sulfate assimilation pathway was observed in the case of high methionine supply, together with a large accumulation of sulfur intermediates. A high sulfate supply seems to provoke considerable cellular stress via sulfite production, resulting in a decrease of the availability of the glutathione pathway's sulfur intermediates. The most limited effect was observed for the cystine supply, suggesting that the intracellular cysteine level is more controlled than that of methionine and sulfate. Using a combination of metabolomic profiling and genetic experiments, we revealed taurine and hypotaurine metabolism in yeast for the first time. On the basis of a phylogenetic study, we then demonstrated that this pathway was lost by some of the hemiascomycetous yeasts during evolution.

Left ventricle assist device: when and which patients should we refer?

Progress in the medical treatment of patients with heart failure with systolic dysfunction, cardiac resynchronization therapy, internal cardiac defibrillators and multidisciplinary management programmes has resulted in dramatic improvements in survival and quality of life; however, this progress has led to an increase in the prevalence of advanced heart failure. In the context of organ shortage for cardiac transplantation, the technological developments in left ventricular assist devices, shown in recent positive clinical studies, provide real hope for patients with advanced heart failure. This article summarizes the most recent clinical studies concerning left ventricular assist devices and discusses for whom and when a left ventricular assist device should be proposed.

Exploration of sulfur metabolism in the yeast Kluyveromyces lactis.

Hemiascomycetes are separated by considerable evolutionary distances and, as a consequence, the mechanisms involved in sulfur metabolism in the extensively studied yeast, Saccharomyces cerevisiae, could be different from those of other species of the phylum. This is the first time that a global view of sulfur metabolism is reported in the biotechnological yeast Kluyveromyces lactis. We used combined approaches based on transcriptome analysis, metabolome profiling, and analysis of volatile sulfur compounds (VSCs). A comparison between high and low sulfur source supplies, i.e., sulfate, methionine, or cystine, was carried out in order to identify key steps in the biosynthetic and catabolic pathways of the sulfur metabolism. We found that sulfur metabolism of K. lactis is mainly modulated by methionine. Furthermore, since sulfur assimilation is highly regulated, genes coding for numerous transporters, key enzymes involved in sulfate assimilation and the interconversion of cysteine to methionine pathways are repressed under conditions of high sulfur supply. Consequently, as highlighted by metabolomic results, intracellular pools of homocysteine and cysteine are maintained at very low concentrations, while the cystathionine pool is highly expandable. Moreover, our results suggest a new catabolic pathway for methionine to VSCs in this yeast: methionine is transaminated by the ARO8 gene product into 4-methylthio-oxobutyric acid (KMBA), which could be exported outside of the cell by the transporter encoded by PDR12 and demethiolated by a spontaneous reaction into methanethiol and its derivatives.

Protection of C. elegans from anoxia by HYL-2 ceramide synthase.

Oxygen deprivation is rapidly deleterious for most organisms. However, Caenorhabditis elegans has developed the ability to survive anoxia for at least 48 hours. Mutations in the DAF-2/DAF-16 insulin-like signaling pathway promote such survival. We describe a pathway involving the HYL-2 ceramide synthase that acts independently of DAF-2. Loss of the ceramide synthase gene hyl-2 results in increased sensitivity of C. elegans to anoxia. C. elegans has two ceramide synthases, hyl-1 and hyl-2, that participate in ceramide biogenesis and affect its ability to survive anoxic conditions. In contrast to hyl-2(lf) mutants, hyl-1(lf) mutants are more resistant to anoxia than normal animals. HYL-1 and HYL-2 have complementary specificities for fatty acyl chains. These data indicate that specific ceramides produced by HYL-2 confer resistance to anoxia.