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result(s) for
"Delpech, Stéphane"
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Large-Scale Screening of Thiol and Fermentative Aroma Production during Wine Alcoholic Fermentation: Exploring the Effects of Assimilable Nitrogen and Peptides
by
Silvano, Anthony
,
Sanchez, Isabelle
,
Mouret, Jean-Roch
in
alcoholic fermentation
,
amino acids
,
ammonium
2020
In alcoholic fermentation, under oenological conditions, the environmental parameters impacting fermentation kinetics and aroma production have been widely studied. The nitrogen content of grape must was found to be one of the most important parameters for both of these aspects of fermentation. Many studies have been performed on the effect of mineral nitrogen addition. However, it has increasingly been observed that the nature of the nitrogen added leads to different results. Our work focused on the effects of peptide addition on both fermentation kinetics and aroma production. Peptides are one of the less well understood sources of assimilable nitrogen, as their incorporation by yeast remains unclear. In this study, we compared the effect of the addition of a “classic” assimilable nitrogen source (ammonium + amino acids) with that of peptide addition in both white and red must fermentation by screening 18 Saccharomyces cerevisiae strains in total. Our data show that peptide addition enhances fermentation kinetics and leads to specific changes in the production of fermentative aromas. The impact of peptides on thiol synthesis is rather limited.
Journal Article
Automated analysis of phylogenetic clusters
by
Ragonnet-Cronin, Manon
,
Fearnhill, Esther
,
Delpech, Valerie
in
Algorithms
,
Analysis
,
Applications software
2013
Background
As sequence data sets used for the investigation of pathogen transmission patterns increase in size, automated tools and standardized methods for cluster analysis have become necessary. We have developed an automated Cluster Picker which identifies monophyletic clades meeting user-input criteria for bootstrap support and maximum genetic distance within large phylogenetic trees. A second tool, the Cluster Matcher, automates the process of linking genetic data to epidemiological or clinical data, and matches clusters between runs of the Cluster Picker.
Results
We explore the effect of different bootstrap and genetic distance thresholds on clusters identified in a data set of publicly available HIV sequences, and compare these results to those of a previously published tool for cluster identification. To demonstrate their utility, we then use the Cluster Picker and Cluster Matcher together to investigate how clusters in the data set changed over time. We find that clusters containing sequences from more than one UK location at the first time point (multiple origin) were significantly more likely to grow than those representing only a single location.
Conclusions
The Cluster Picker and Cluster Matcher can rapidly process phylogenetic trees containing tens of thousands of sequences. Together these tools will facilitate comparisons of pathogen transmission dynamics between studies and countries.
Journal Article
Guidance landscapes unveiled by quantitative proteomics to control reinnervation in adult visual system
2022
In the injured adult central nervous system (CNS), activation of pro-growth molecular pathways in neurons leads to long-distance regeneration. However, most regenerative fibers display guidance defects, which prevent reinnervation and functional recovery. Therefore, the molecular characterization of the proper target regions of regenerative axons is essential to uncover the modalities of adult reinnervation. In this study, we use mass spectrometry (MS)-based quantitative proteomics to address the proteomes of major nuclei of the adult visual system. These analyses reveal that guidance-associated molecules are expressed in adult visual targets. Moreover, we show that bilateral optic nerve injury modulates the expression of specific proteins. In contrast, the expression of guidance molecules remains steady. Finally, we show that regenerative axons are able to respond to guidance cues ex vivo, suggesting that these molecules possibly interfere with brain target reinnervation in adult. Using a long-distance regeneration model, we further demonstrate that the silencing of specific guidance signaling leads to rerouting of regenerative axons in vivo. Altogether, our results suggest ways to modulate axon guidance of regenerative neurons to achieve circuit repair in adult.
Long-distance regeneration in the adult central nervous system shows severe guidance defects preventing circuit reformation. Here, the authors reveal a comprehensive map of guidance cues in the adult visual system that can be used to modulate the path of regenerating axons to achieve circuit repair.
Journal Article
A comprehensive study of phospholipid fatty acid rearrangements in metabolic syndrome: correlations with organ dysfunction
by
Sébille, Stéphane
,
Bescond, Jocelyn
,
Vandebrouck, Clarisse
in
Animals
,
Carbon
,
cardiovascular disease
2020
The balance within phospholipids (PLs) between saturated fatty acids and monounsaturated or polyunsaturated fatty acids is known to regulate the biophysical properties of cellular membranes. As a consequence, in many cell types, perturbing this balance alters crucial cellular processes, such as vesicular budding and the trafficking/function of membrane-anchored proteins. The worldwide spread of the Western diet, which is highly enriched in saturated fats, has been clearly correlated with the emergence of a complex syndrome known as metabolic syndrome (MetS). MetS is defined as a cluster of risk factors for cardiovascular diseases, type 2 diabetes and hepatic steatosis; however, no clear correlations have been established between diet-induced fatty acid redistribution within cellular PLs and the severity/chronology of the symptoms associated with MetS or the function of the targeted organs. To address this issue, in this study we analyzed PL remodeling in rats exposed to a high-fat/high-fructose diet (HFHF) over a 15-week period. PL remodeling was analyzed in several organs, including known MetS targets. We show that fatty acids from the diet can redistribute within PLs in a very selective manner, with phosphatidylcholine being the preferred sink for this redistribution. Moreover, in the HFHF rat model, most organs are protected from this redistribution, at least during the early onset of MetS, at the expense of the liver and skeletal muscles. Interestingly, such a redistribution correlates with clear-cut alterations in the function of these organs. This article has an associated First Person interview with the first author of the paper.
Journal Article
Adult Mouse Retina Explants: From ex vivo to in vivo Model of Central Nervous System Injuries
by
Schaeffer, Julia
,
Albert, Floriane
,
Nawabi, Homaira
in
Antibodies
,
Axon guidance
,
axon regeneration
2020
In mammals, adult neurons fail to regenerate following any insult to adult central nervous system (CNS), which leads to a permanent and irreversible loss of motor and cognitive functions. For a long time, much effort has been deployed to uncover mechanisms of axon regeneration in the CNS. Even if some cases of functional recovery have been reported, there is still a discrepancy regarding the functionality of a neuronal circuit upon lesion. Today, there is a need not only to identify new molecules implicated in adult CNS axon regeneration, but also to decipher the fine molecular mechanisms associated with regeneration failure. Here, we propose to use cultures of adult retina explants to study all molecular and cellular mechanisms that occur during CNS regeneration. We show that adult retinal explant cultures have the advantages to (i) recapitulate all the features observed in vivo , including axon regeneration induced by intrinsic factors, and (ii) be an ex vivo set-up with high accessibility and many downstream applications. Thanks to several examples, we demonstrate that adult explants can be used to address many questions, such as axon guidance, growth cone formation and cytoskeleton dynamics. Using laser guided ablation of a single axon, axonal injury can be performed at a single axon level, which allows to record early and late molecular events that occur after the lesion. Our model is the ideal tool to study all molecular and cellular events that occur during CNS regeneration at a single-axon level, which is currently not doable in vivo . It is extremely valuable to address unanswered questions of neuroprotection and neuroregeneration in the context of CNS lesion and neurodegenerative diseases.
Journal Article
Electrochemical Behavior of Al/Mg Alloys Immobilized in a Magnesium Potassium Phosphate Cement-Based Mortar
2023
Portland cement is extensively used for the conditioning of radioactive waste. However, its high alkalinity is a serious obstacle to the stabilization of waste containing aluminum metal since aluminum is oxidized by the pore solution with the production of dihydrogen. This work investigates the potential of an alternative binder, magnesium potassium phosphate (MKP) cement, for the stabilization of Al–Mg alloys comprising 2 to 4.5 wt% of Mg and other metallic impurities. The objective is to assess the influence of the alloy composition on its reactivity in the cementitious matrix at earlier ages, as well as at later ages, when the cement has reached a significant reaction degree. Two complementary techniques are used. Gas chromatography shows that the dihydrogen release, resulting from the corrosion process, is not influenced by the magnesium content in the alloy. Electrochemical impedance spectroscopy provides qualitative information about the corrosion but also makes it possible to assess the corrosion current using an equivalent electrical circuit linked to the kinetic parameters of the postulated corrosion mechanism. Over a one-year period, the corrosion current of the alloys, regardless of their Mg content, is reduced by almost three orders of magnitude in MKP mortar as compared to Portland-cement-based mortar.
Journal Article
Global Trends in CD4 Cell Count at the Start of Antiretroviral Therapy: Collaborative Study of Treatment Programs
by
Riggen, Larry
,
Anastos, Kathryn
,
Panayidou, Klea
in
Adult
,
and Commentaries
,
Anti-HIV Agents - therapeutic use
2018
Early initiation of combination antiretroviral therapy (cART), at higher CD4 cell counts, prevents disease progression and reduces sexual transmission of human immunodeficiency virus (HIV). We describe the temporal trends in CD4 cell counts at the start of cART in adults from low-income, lower-middle-income, upper-middle-income, and high-income countries (LICs, LMICs, UMICs, and HICs, respectively).
We included HIV-infected individuals aged ≥16 years who started cART between 2002 and 2015 in a clinic participating in the International epidemiology Databases to Evaluate AIDS (IeDEA) or the Collaboration of Observational HIV Epidemiological Research in Europe (COHERE). Missing CD4 cell counts at the start of cART were estimated through multiple imputation. Weighted mixed-effect models were used to smooth trends in median CD4 cell counts.
A total of 951855 adults from 16 LICs, 11 LMICs, 9 UMICs, and 19 HICs were included. Overall, the modeled median CD4 cell count at the start of cART increased from 2002 to 2015, from 78/µL (95% confidence interval, 58-104/µL) to 287/µL (250-328/µL) in LICs, from 99/µL (71-140/µL) to 234/µL (192-285/µL) in LMICs, from 71/µL (49-104/µL) to 311/µL (255-379/µL) in UMICs, and from 161/µL (143-181/µL) to 327/µL (286-372/µL) in HICs. In LICs, LMICs, and UMICs, the increase was more pronounced in women; in HICs, the opposite was observed.
Median CD4 cell counts at the start of cART increased in all income groups, but generally remained below 350/μL in 2015. Substantial additional efforts and resources are required to achieve earlier diagnosis, linkage to care, and initiation of cART.
Journal Article
Persistence of HIV-1 Transmitted Drug Resistance Mutations
by
Castro, Hannah
,
Phillips, Andrew
,
Pillay, Deenan
in
Adolescent
,
Adult
,
Anti-HIV Agents - pharmacology
2013
There are few data on the persistence of individual human immunodeficiency virus type 1 (HIV-1) transmitted drug resistance (TDR) mutations in the absence of selective drug pressure. We studied 313 patients in whom TDR mutations were detected at their first resistance test and who had a subsequent test performed while ART-naive. The rate at which mutations became undetectable was estimated using exponential regression accounting for interval censoring. Most thymidine analogue mutations (TAMs) and T215 revertants (but not T215F/Y) were found to be highly stable, with NNRTI and PI mutations being relatively less persistent. Our estimates are important for informing HIV transmission models.
Journal Article
Asymptomatic bacteriuria prior to partial and radical nephrectomy: To screen or not to screen? Results from the national and multicenter TOCUS database
by
Dinh, Aurélien
,
Vallée, Maxime
,
Poussot, Baptiste
in
Anti-Bacterial Agents
,
Anti-Bacterial Agents - therapeutic use
,
Antibiotics
2024
Introduction
In the era of increased bacterial resistance, the main strategy is to reduce the prescription of antibiotics when possible. Nowadays, it is highly recommended to screen for asymptomatic bacteriuria (ABU), prior to urological surgery with potential mucosal breach or urine exposure. Screening and treating urinary colonization is a strategy widely adopted before radical and partial nephrectomy but without any evidence. Our main end point in this study is to analyze the relationship between preoperative urine culture and the risk of postoperative febrile urinary tract infection (UTI) or surgical-site infection (SSI) in partial or radical nephrectomy patients.
Methods
We conducted a multicenter retrospective cohort study between January 2016 and January 2023 in 11 French tertiary referral hospitals (TOCUS database). We collected the data for 269 patients including several pre-, intra-, and post-operative variables that could potentially increase the risk of postoperative UTI and SSI including preoperative urinary culture results.
Results
The incidence rate of postoperative UTI and SSI was 8.9% in our study. After conducting a logistic multivariate analysis, a propensity score matching analysis, and a subgroup analysis, we found no significant correlation between the urine culture and the postoperative UTI risk [OR = 1.2 (0.5–2.7) (
p
= 0.7)]. Only the postoperative non-infectious complications were related to a higher risk of postoperative UTI [OR = 12 (4–37),
p
< 0.001)].
Conclusion
Our research shows that screening and treating for ABU prior to radical or partial nephrectomy seems to be unnecessary to prevent postoperative UTI and SSI.
Journal Article
Post‐exercise hypotension in male spontaneously hypertensive rats: The issue of calculation method
2023
In spontaneously hypertensive rats, exercise can lead to a post‐exercise decrease in blood pressure, named post‐exercise hypotension (PEH). This can be following physical training but also after a single bout of mild to moderate exercise when measured with tail‐cuff or externalized catheter methods. Our aim was to assess the PEH obtained with different calculation methods and to compare the magnitude of this effect induced by a moderate‐intensity continuous exercise or a high‐intensity intermittent exercise. Thirteen 16‐week‐old male spontaneously hypertensive rats performed two types of aerobic exercise (continuous or intermittent) on a treadmill. Arterial pressure was recorded by telemetry for 24 h which was started 3 h before physical exercise. Based on the literature, PEH was first evaluated with two different baseline values, and then with three different approaches. We observed that the identification of PEH depended on the method used to measure the rest value, and that its amplitude was also influenced by the calculation approach and the type of exercise performed. Hence, the calculation method and the amplitude of the detected PEH can significantly influence their physiological and pathophysiological inferences. In spontaneously hypertensive rats, exercise can lead to a post‐exercise decrease in blood pressure recording by radio‐telemetry, nammed post‐exercise hypotension. Hence, the choice of the calculation method and the amplitude of the detected hypotension can greatly influence their physiological and pathophysiological inferences
Journal Article