Holistic integration of omics data reveals the drivers that shape the ecology of microbial meat spoilage scenarios

Background

The use of omics data for monitoring the microbial flow of fresh meat products along a production line and the development of spoilage prediction tools from these data is a promising but challenging task. In this context, we produced a large multivariate dataset (over 600 samples) obtained on the production lines of two similar types of fresh meat products (poultry and raw pork sausages). We describe a full analysis of this dataset in order to decipher how the spoilage microbial ecology of these two similar products may be shaped differently depending on production parameter characteristics.

Methods

Our strategy involved a holistic approach to integrate unsupervised and supervised statistical methods on multivariate data (OTU-based microbial diversity; metabolomic data of volatile organic compounds; sensory measurements; growth parameters), and a specific selection of potential uncontrolled (initial microbiota composition) or controlled (packaging type; lactate concentration) drivers.

Results

Our results demonstrate that the initial microbiota, which is shown to be very different between poultry and pork sausages, has a major impact on the spoilage scenarios and on the effect that a downstream parameter such as packaging type has on the overall evolution of the microbial community. Depending on the process, we also show that specific actions on the pork meat (such as deboning and defatting) elicit specific food spoilers such as Dellaglioa algida, which becomes dominant during storage. Finally, ecological network reconstruction allowed us to map six different metabolic pathways involved in the production of volatile organic compounds involved in spoilage. We were able connect them to the different bacterial actors and to the influence of packaging type in an overall view. For instance, our results demonstrate a new role of Vibrionaceae in isopropanol production, and of Latilactobacillus fuchuensis and Lactococcus piscium in methanethiol/disylphide production. We also highlight a possible commensal behavior between Leuconostoc carnosum and Latilactobacillus curvatus around 2,3-butanediol metabolism.

Conclusion

We conclude that our holistic approach combined with large-scale multi-omic data was a powerful strategy to prioritize the role of production parameters, already known in the literature, that shape the evolution and/or the implementation of different meat spoilage scenarios.

A Bayesian Approach to Describe and Simulate the pH Evolution of Fresh Meat Products Depending on the Preservation Conditions

Measuring the pH of meat products during storage represents an efficient way to monitor microbial spoilage, since pH is often linked to the growth of several spoilage-associated microorganisms under different conditions. The present work aimed to develop a modelling approach to describe and simulate the pH evolution of fresh meat products, depending on the preservation conditions. The measurement of pH on fresh poultry sausages, made with several lactate formulations and packed under three modified atmospheres (MAP), from several industrial production batches, was used as case-study. A hierarchical Bayesian approach was developed to better adjust kinetic models while handling a low number of measurement points. The pH changes were described as a two-phase evolution, with a first decreasing phase followed by a stabilisation phase. This stabilisation likely took place around the 13th day of storage, under all the considered lactate and MAP conditions. The effects of lactate and MAP on pH previously observed were confirmed herein: (i) lactate addition notably slowed down acidification, regardless of the packaging, whereas (ii) the 50%CO₂-50%N₂ MAP accelerated the acidification phase. The Bayesian modelling workflow—and the script—could be used for further model adaptation for the pH of other food products and/or other preservation strategies.

Application of a path-modelling approach for deciphering causality relationships between microbiota, volatile organic compounds and off-odour profiles during meat spoilage

Microbiological spoilage of meat is considered as a process which involves mainly bacterial metabolism leading to degradation of meat sensory qualities. Studying spoilage requires the collection of different types of experimental data encompassing microbiological, physicochemical and sensorial measurements. Within this framework, the objective herein was to carry out a multiblock path modelling workflow to decipher causality relationships between different types of spoilage-related responses: composition of microbiota, volatilome and off-odour profiles. Analyses were performed with the Path-ComDim approach on a large-scale dataset collected on fresh turkey sausages. This approach enabled to quantify the importance of causality relationships determined a priori between each type of responses as well as to identify important responses involved in spoilage, then to validate causality assumptions. Results were very promising: the data integration confirmed and quantified the causality between data blocks, exhibiting the dynamical nature of spoilage, mainly characterized by the evolution of off-odour profiles caused by the production of volatile organic compounds such as ethanol or ethyl acetate. This production was possibly associated with several bacterial species like Lactococcus piscium, Leuconostoc gelidum, Psychrobacter sp. or Latilactobacillus fuchuensis. Likewise, the production of acetoin and diacetyl in meat spoilage was highlighted. The Path-ComDim approach illustrated here with meat spoilage can be applied to other large-scale and heterogeneous datasets associated with pathway scenarios and represents a promising key tool for deciphering causality in complex biological phenomena.

Quantification of Campylobacter jejuni gene expression after successive stresses mimicking poultry slaughtering steps

Broiler meat is considered as the most important source of the foodborne pathogen Campylobacter jejuni. Exposure to stress conditions encountered during the slaughtering process may induce bacterial adaptation mechanisms, and enhance or decrease pathogen resistance to subsequent stress. This adaptation may result from changes in bacterial gene expression. This study aims to accurately quantify the expression of selected C. jejuni genes after stresses inspired from the poultry slaughtering process. RT-qPCR was used to quantify gene expression of 44 genes in three strains after successive heat and cold stresses. Main results indicated that 26 genes out of 44 were differentially expressed following the successive thermal stresses. Three clusters of genes were differentially expressed according to the strain and the stress condition. Up-regulated genes mainly included genes involved in the heat shock response, whereas down-regulated genes belonged to metabolic pathways (such as lipid, amino-acid metabolisms). However, four genes were similarly overexpressed in the three strains; they might represent indicators of the thermal stress response at the species scale. Advances in the molecular understanding of the stress response of pathogenic bacteria, such as Campylobacter, in real-life processing conditions will make it possible to identify technological levers and better mitigate the microbial risk.

Public health risk-benefit assessment of red meat in France: Current consumption and alternative scenarios

Consumption of red meat has been associated with the risks of colorectal cancer (CRC), cardiovascular disease (CVD), foodborne-pathogen related diseases and with the potential benefit obtained by reduction of iron deficiency anemia (IDA). Based on probabilistic models, current risks and benefit for the French population were aggregated into a single metric, the disability adjusted life years (DALY). In France, per 100,000 people, current red meat consumption was responsible for a mean of 19 DALYs due to CRC, 21 DALYs to CVD and 7 DALYs to foodborne diseases. Current consumption of iron throughout the diet led to a mean of 15 DALYs due to IDA. To mitigate the risks, scenarios were built per sub-population of age and gender. Among adult and elderly population, the big meat eaters would benefit to adhere to the current recommendation (less than 500 g/w): the risks of CRC and CVD would decrease. Regarding IDA (scenario built with fixed ground beef amount), for young population, a consumption of 375g/w would be sufficient to eliminate the burden while for 25-44 years-old females, 455g/w would reduce IDA, but not entirely. This study highlighted the importance of assessing health risk-benefit per sub-populations and the necessity of communicating the results accordingly.

Critical Analysis of Pork QMRA Focusing on Slaughterhouses: Lessons from the Past and Future Trends

Foodborne microbial diseases have a significant impact on public health, leading to millions of human illnesses each year worldwide. Pork is one of the most consumed meat in Europe but may also be a major source of pathogens introduced all along the farm-to-fork chain. Several quantitative microbial risk assessment (QMRA) have been developed to assess human health risks associated with pork consumption and to evaluate the efficiency of different risk reduction strategies. The present critical analysis aims to review pork QMRA. An exhaustive search was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) methodology. It resulted in identification of a collection of 2489 papers including 42 on QMRA, after screening. Among them, a total of 29 studies focused on Salmonella spp. with clear concern on impacts at the slaughterhouse, modeling the spreading of contaminations and growth at critical stages along with potential reductions. Along with strict compliance with good hygiene practices, several potential risk mitigation pathways were highlighted for each slaughterhouse step. The slaughterhouse has a key role to play to ensure food safety of pork-based products but consideration of the whole farm-to-fork chain is necessary to enable better control of bacteria. This review provides an analysis of pork meat QMRA, to facilitate their reuse, and identify gaps to guide future research activities.

Review of Quantitative Microbial Risk Assessment in Poultry Meat: The Central Position of Consumer Behavior

Food of animal origin, especially meat products, represent the main vehicle of foodborne pathogens and so are implicated in foodborne outbreaks. Poultry meat is a widely consumed food in various forms, but it is also a reservoir of thermotolerant Campylobacter and Salmonella bacterial species. To assess human health risks associated with pathogenic bacteria in poultry meat, the use of quantitative microbial risk assessment (QMRA) has increased over the years as it is recognized to address complex food safety issues and is recommended by health authorities. The present project reviewed poultry meat QMRA, identified key steps of the farm-to-fork chain with significant impacts on food safety, highlighted current knowledge gaps, and provided risk mitigation advices. A PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses)-based systematic analysis was carried out and enabled the collection of 4056 studies including 42 QMRA kept for analysis after screening. The latter emphasized Campylobacter spp. and Salmonella spp. contaminations during the consumer stage as the main concern. The role of consumer handling on cross-contamination and undercooking events were of major concern. Thus, proper hygiene and safety practices by consumers have been suggested as the main intervention and would need to be followed with regular surveys to assess behavior changes and reduce knowledge gaps.

Quantitative approach to assess the compliance to a performance objective (PO) of Campylobacter jejuni in poultry meat in France

Predictive modelling is used in microbiological risk assessment to quantify the growth and inactivation of microorganisms through the use of mathematical models. Campylobacter jejuni is one of the main foodborne pathogens and broiler meat is considered as the most important source of human campylobacteriosis. The purpose of this study was to assess the effects of heating and chilling during the poultry slaughter process on inactivation kinetics of Campylobacter jejuni during chilled storage in order to predict its contamination level prior to preparation and consumption in the consumer's home, and then to assess the compliance to a Performance Objective (PO). Three strains of C. jejuni were submitted to consecutive heat (54 °C for 3 min) and cold (3 °C for 2 h) stresses, mimicking the two main slaughtering steps, i.e. scalding and chilling, by inoculating chicken fillets with three different concentrations (4, 6 and 8 log₁₀ CFU/g). Fillets were then stored at 6 °C during 17 days under the modified atmosphere currently used by food processors (70% O₂/30% CO₂). For all strains, bacterial log reduction was the lowest when inoculated at 8 log₁₀ CFU/g. One strain showed an enhanced resistance during cold storage after application of stressing steps, suggesting an impact of the cell history on further bacterial resistance. Taking strain variability into account, after six days of storage, predictions showed compliance of ready-to-be-cooked chicken meat with a hypothetical PO of 2.55 log₁₀ CFU/g, value set before the meat enters the consumer's home by the ICMSF (International Commission on Microbiological Specifications for Foods). This study opens the path to assess the compliance to a PO of Campylobacter jejuni in poultry meat and more generally provides inputs to refine microbiological risk assessment by taking into account the cell history and more particularly the impact of stressful steps on the subsequent inactivation at consumer's home.

Spoilage of Chilled Fresh Meat Products during Storage: A Quantitative Analysis of Literature Data

A literature search was performed on spoilage of fresh meat products by combining keyword query, text mining and expert elicitation. From the 258 collected studies, a quantitative analysis was first performed to identify the methods which are the most used to evaluate spoilage beside the preservation strategies suggested. In a second step focusing on a subset of 24 publications providing quantitative data on spoilage occurrence time, associations between spoilage occurrence time of meat products and specific spoilage indicators were investigated. The analysis especially focused on factors well represented in the 24 publications, i.e., gas packaging (O2 and CO2) and storage temperature. Relationships between spoilage occurrence and several microbiological indicators were also sought. The results point out possible advantages of removing dioxygen in packaging to delay spoilage occurrence, whereas, in the presence of dioxygen, the carbon dioxide proportion in the gas mixtures was shown to influence spoilage occurrence. The collected data clearly reveal a potentially protective role of lactic acid bacteria. Besides, while a spoilage role could be attributed to Pseudomonas spp., the growth of mesophilic aerobic microbes, Brochothrix spp. and Enterobacteriaceae seemed independent of spoilage occurrence time.

Large-scale multivariate dataset on the characterization of microbiota diversity, microbial growth dynamics, metabolic spoilage volatilome and sensorial profiles of two industrially produced meat products subjected to changes in lactate concentration and packaging atmosphere

Data in this article provide detailed information on the diversity of bacterial communities present on 576 samples of raw pork or poultry sausages produced industrially in 2017. Bacterial growth dynamics and diversity were monitored throughout the refrigerated storage period to estimate the impact of packaging atmosphere and the use of potassium lactate as chemical preservative. The data include several types of analysis aiming at providing a comprehensive microbial ecology of spoilage during storage and how the process parameters do influence this phenomenon. The analysis includes: the gas content in packaging, pH, chromametric measurements, plate counts (total mesophilic aerobic flora and lactic acid bacteria), sensorial properties of the products, meta-metabolomic quantification of volatile organic compounds and bacterial community metagenetic analysis. Bacterial diversity was monitored using two types of amplicon sequencing (16S rRNA and GyrB encoding genes) at different time points for the different conditions (576 samples for gyrB and 436 samples for 16S rDNA). Sequencing data were generated by using Illumina MiSeq. The sequencing data have been deposited in the bioproject PRJNA522361. Samples accession numbers vary from SAMN10964863 to SAMN10965438 for gyrB amplicon and from SAMN10970131 to SAMN10970566 for 16S.

A Systematic Review of Beef Meat Quantitative Microbial Risk Assessment Models

Each year in Europe, meat is associated with 2.3 million foodborne illnesses, with a high contribution from beef meat. Many of these illnesses are attributed to pathogenic bacterial contamination and inadequate operations leading to growth and/or insufficient inactivation occurring along the whole farm-to-fork chain. To ensure consumer health, decision-making processes in food safety rely on Quantitative Microbiological Risk Assessment (QMRA) with many applications in recent decades. The present study aims to conduct a critical analysis of beef QMRAs and to identify future challenges. A systematic approach, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was used to collate beef QMRA models, identify steps of the farm-to-fork chain considered, and analyze inputs and outputs included as well as modelling methods. A total of 2343 articles were collected and 67 were selected. These studies focused mainly on western countries and considered Escherichia coli (EHEC) and Salmonella spp. pathogens. Future challenges were identified and included the need of whole-chain assessments, centralization of data collection processes, and improvement of model interoperability through harmonization. The present analysis can serve as a source of data and information to inform QMRA framework for beef meat and will help the scientific community and food safety authorities to identify specific monitoring and research needs.

Inactivation of Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica under High Hydrostatic Pressure: A Quantitative Analysis of Existing Literature Data

High hydrostatic pressure processing (HPP) is a mild preservation technique, and its use for processing foods has been widely documented in the literature. However, very few quantitative synthesis studies have been conducted to gather and analyze bacterial inactivation data to identify the mechanisms of HPP-induced bacterial inactivation. The purpose of this study was to conduct a quantitative analysis of three-decimal reduction times (t_3δ) from a large set of existing studies to determine the main influencing factors of HPP-induced inactivation of three foodborne pathogens (Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica) in various foods. Inactivation kinetics data sets from 1995 to 2017 were selected, and t_3δ values were first estimated by using the nonlinear Weibull model. Bayesian inference was then used within a metaregression analysis to build and test several models and submodels. The best model (lowest error and most parsimonious) was a hierarchical mixed-effects model including pressure intensity, temperature, study, pH, species, and strain as explicative variables and significant factors. Values for t_3δ and Z_P associated with inactivation under HPP were estimated for each bacterial pathogen, with their associated variability. Interstudy variability explained most of the variability in t_3δ values. Strain variability was also important and exceeded interstudy variability for S. aureus, which prevented the development of an overall model for this pathogen. Meta-analysis is not often used in food microbiology but was a valuable quantitative tool for modeling inactivation of L. monocytogenes and Salmonella in response to HPP treatment. Results of this study could be useful for refining quantitative assessment of the effects of HPP on vegetative foodborne pathogens or for more precisely designing costly and labor-intensive experiments with foodborne pathogens.

Estimation of the Burden of Iron Deficiency Anemia in France from Iron Intake: Methodological Approach

: Dietary iron deficiency (ID) is the first nutritional deficiency in the world, in terms of disability adjusted life years (DALY). This nutritional deficiency may lead to anemia, especially among children, adolescents, and adult women. The aim of this study was to build an original probabilistic model to quantitatively assess the ID, the iron deficiency anemia (IDA) and the subsequent health burden in France expressed in DALY, per age class and gender. The model considered the distribution of absorbed iron intake, the iron requirement distribution established by the European Food Safety Authority and the iron status in France. Uncertainty due to lack of data and variability due to biological diversity were taken into account and separated using a second-order Monte Carlo procedure. A total of 1290 (95% CI = 1230-1350) IDA cases corresponding to 16 (95% CI = 11-20) DALY were estimated per 100,000 individuals per year. The major contributors to IDA burden were menstruating females aged from 25 to 44 years old. Then, a consumption scenario was built with ground beef as intake, an increase in red meat consumption to 100 g/d would not eliminate entirely the IDA burden. The quantitative methodology applied here for France could be reused for other populations.

Estimation of the burden of disease attributable to red meat consumption in France: Influence on colorectal cancer and cardiovascular diseases

The consumption of red meat has been associated with colorectal cancer (CRC) and cardiovascular disease (CVD) worldwide. The objective of this study was to assess quantitatively the burden of disease of CRC and CVD due to the consumption of red meat in France. A probabilistic risk assessment model quantifying the risk, deaths and disability adjusted life years (DALY) of both outcomes was built. In the model, uncertainty and variability were propagated separately. The model used data on current CRC and CVD incidence and red meat consumption in France, as well as dose-response from epidemiological studies. Results were given by age class and gender. A total of 19 [95% CI = 8-33] DALY per 100,000 people per year for CRC associated with red meat consumption was estimated. For CVD, 21 [95% CI = 12-32] DALY per 100,000 people per year was estimated. The uncertainty was mainly due to the dose-response, as revealed by a sensitivity analysis. A scenario analysis, performed on red meat intake, highlighted that consumption of less than 65 g per day could limit the risk of CRC and CVD in the most affected sub-populations.

Selection procedure of bioprotective cultures for their combined use with High Pressure Processing to control spore-forming bacteria in cooked ham

High Pressure Processing (HPP) and biopreservation can contribute to food safety by inactivation of bacterial contaminants. However these treatments are inefficient against bacterial endospores. Moreover, HPP can induce spore germination. The objective of this study was to select lactic acid bacteria strains to be used as bioprotective cultures, to control vegetative cells of spore-forming bacteria in ham after application of HPP. A collection of 63 strains of various origins was screened for their antagonistic activity against spore-forming Bacillus and Clostridium species and their ability to resist to HPP. Some safety requirements should also be considered prior to their introduction into the food chain. Hence, the selection steps included the assessment of biogenic amine production and antibiotic resistance. No strain produced histamine above the threshold detection level of 50 ppm. From the assessment of antibiotic resistance against nine antibiotics, 14 susceptible strains were kept. Antagonistic action of the 14 strains was then assessed by the well diffusion method against pathogenic or spoilage spore-forming species as Bacillus cereus, Clostridium sp. like botulinum, Clostridium frigidicarnis, and Clostridium algidicarnis. One Lactobacillus curvatus strain and one Lactococcus lactis strain were ultimately selected for their widest inhibitory spectrum and their potential production of bacteriocin. A Lactobacillus plantarum strain was included as control. Their resistance to HPP and ability to regrow during chilled storage was then assessed in model ham liquid medium. Treatments of pressure intensities of 400, 500, and 600 MPa, and durations of 1, 3, 6, and 10 min were applied. After treatment, cultures were incubated at 8 °C during 30 days. Inactivation curves were then fitted by using a reparameterized Weibull model whereas growth curves were modelled with a logistic model. Although the two Lactobacillus strains were more resistant than L. lactis to HPP, the latter was the only strain able to regrow following HPP. The absence of biogenic amine production of this strain after growth on diced cube cooked ham was also shown. In conclusion this L. lactis strain could be selected as representing the best candidate for a promising preservative treatment combining biopreservation and HPP to control spore-forming bacteria in cooked ham.

Quantification of Campylobacter jejuni contamination on chicken carcasses in France

Highly prevalent in poultry, Campylobacter is a foodborne pathogen which remains the primary cause of enteritis in humans. Several studies have determined prevalence and contamination level of this pathogen throughout the food chain. However it is generally performed in a deterministic way without considering heterogeneity of contamination level. The purpose of this study was to quantify, using probabilistic tools, the contamination level of Campylobacter spp. on chicken carcasses after air-chilling step in several slaughterhouses in France. From a dataset (530 data) containing censored data (concentration <10CFU/g), several factors were considered, including the month of sampling, the farming method (standard vs certified) and the sampling area (neck vs leg). All probabilistic analyses were performed in R using fitdistrplus, mc2d and nada packages. The uncertainty (i.e. error) generated by the presence of censored data was small (ca 1 log₁₀) in comparison to the variability (i.e. heterogeneity) of contamination level (3 log₁₀ or more), strengthening the probabilistic analysis and facilitating result interpretation. The sampling period and sampling area (neck/leg) had a significant effect on Campylobacter contamination level. More precisely, two "seasons" were distinguished: one from January to May, another one from June to December. During the June-to-December season, the mean Campylobacter concentration was estimated to 2.6 [2.4; 2.8] log₁₀ (CFU/g) and 1.8 [1.5; 2.0] log₁₀ (CFU/g) for neck and leg, respectively. The probability of having >1000CFU/g (higher limit of European microbial criterion) was estimated to 35.3% and 12.6%, for neck and leg, respectively. In contrast, during January-to-May season, the mean contamination level was estimated to 1.0 [0.6; 1.3] log₁₀ (CFU/g) and 0.6 [0.3; 0.9] log₁₀ (CFU/g) for neck and leg, respectively. The probability of having >1000CFU/g was estimated to 13.5% and 2.0% for neck and leg, respectively. An accurate quantification of contamination level enables industrials to better adapt their processing and hygiene practices. These results will also help in refining exposure assessment models.

Development and Application of a Probabilistic Risk-Benefit Assessment Model for Infant Feeding Integrating Microbiological, Nutritional, and Chemical Components

A probabilistic and interdisciplinary risk-benefit assessment (RBA) model integrating microbiological, nutritional, and chemical components was developed for infant milk, with the objective of predicting the health impact of different scenarios of consumption. Infant feeding is a particular concern of interest in RBA as breast milk and powder infant formula have both been associated with risks and benefits related to chemicals, bacteria, and nutrients, hence the model considers these three facets. Cronobacter sakazakii, dioxin-like polychlorinated biphenyls (dl-PCB), and docosahexaenoic acid (DHA) were three risk/benefit factors selected as key issues in microbiology, chemistry, and nutrition, respectively. The present model was probabilistic with variability and uncertainty separated using a second-order Monte Carlo simulation process. In this study, advantages and limitations of undertaking probabilistic and interdisciplinary RBA are discussed. In particular, the probabilistic technique was found to be powerful in dealing with missing data and to translate assumptions into quantitative inputs while taking uncertainty into account. In addition, separation of variability and uncertainty strengthened the interpretation of the model outputs by enabling better consideration and distinction of natural heterogeneity from lack of knowledge. Interdisciplinary RBA is necessary to give more structured conclusions and avoid contradictory messages to policymakers and also to consumers, leading to more decisive food recommendations. This assessment provides a conceptual development of the RBA methodology and is a robust basis on which to build upon.

Fondaparinux upregulates thrombomodulin and the endothelial protein C receptor during early-stage reperfusion in a rat model of myocardial infarction

INTRODUCTION

Fondaparinux (FDX) was demonstrated to be cardioprotective in a rat model of myocardial ischemia reperfusion. In this model, FDX reduced infarct size after 2h of reperfusion, involving the activation of the survivor activating factor enhancement (SAFE) pathway as early as 30min post-reperfusion. Our aim was to study if this cardioprotection could be explained by anti-inflammatory mechanisms and a protective effect on vessels.

METHODS

Wistar male rats were subjected to 40minutes (min) of myocardial ischemia, followed by 30min or 2h of reperfusion. Rats were randomized into four groups: control 30min (n=7), FDX 30min (n=7), control 2h (n=7), and FDX 2h (n=7). The FDX groups received 10mg/kg injection of FDX 10min prior to initiating reperfusion. We studied: 1) mRNA expression of endothelial markers, such as thrombomodulin (TM), endothelial protein C receptor (EPCR), and tissue factor (TF) and 2) proteic expression of ICAM-1, NF-κB, IκB, and JNK. Leukocyte infiltration was assessed by histochemistry. We also evaluated TM and EPCR mRNA expression in a model of isolated rat mesenteric arteries incubated with FDX.

RESULTS

FDX upregulated the expression of TM and EPCR mRNA in the models of myocardial infarction and isolated mesenteric arteries. No difference was observed between the treated and control groups regarding the expression of pro-inflammatory signaling proteins, adhesion molecules, and leukocyte infiltration after 2h of reperfusion.

CONCLUSION

The cardioprotective effect of FDX at early-stage reperfusion could be related to vascular protection, yet not to an anti-inflammatory effect.

Original 2-(3-Alkoxy-1H-pyrazol-1-yl)azines Inhibitors of Human Dihydroorotate Dehydrogenase (DHODH)

Following our discovery of human dihydroorotate dehydrogenase (DHODH) inhibition by 2-(3-alkoxy-1H-pyrazol-1-yl)pyrimidine derivatives as well as 2-(4-benzyl-3-ethoxy-5-methyl-1H-pyrazol-1-yl)-5-methylpyridine, we describe here the syntheses and evaluation of an array of azine-bearing analogues. As in our previous report, the structure-activity study of this series of human DHODH inhibitors was based on a phenotypic assay measuring measles virus replication. Among other inhibitors, this round of syntheses and biological evaluation iteration led to the highly active 5-cyclopropyl-2-(4-(2,6-difluorophenoxy)-3-isopropoxy-5-methyl-1H-pyrazol-1-yl)-3-fluoropyridine. Inhibition of DHODH by this compound was confirmed in an array of in vitro assays, including enzymatic tests and cell-based assays for viral replication and cellular growth. This molecule was found to be more active than the known inhibitors of DHODH, brequinar and teriflunomide, thus opening perspectives for its use as a tool or for the design of an original series of immunosuppressive agent. Moreover, because other series of inhibitors of human DHODH have been found to also affect Plasmodium falciparum DHODH, all the compounds were assayed for their effect on P. falciparum growth. However, the modest in vitro inhibition solely observed for two compounds did not correlate with their inhibition of P. falciparum DHODH.

Original 2-(3-alkoxy-1H-pyrazol-1-yl)pyrimidine derivatives as inhibitors of human dihydroorotate dehydrogenase (DHODH)

From a research program aimed at the design of new chemical entities followed by extensive screening on various models of infectious diseases, an original series of 2-(3-alkoxy-1H-pyrazol-1-yl)pyrimidines endowed with notable antiviral properties were found. Using a whole cell measles virus replication assay, we describe here some aspects of the iterative process that, from 2-(4-benzyl-3-ethoxy-5-methyl-1H-pyrazol-1-yl)pyrimidine, led to 2-(4-(2,6-difluorophenoxy)-3-isopropoxy-5-methyl-1H-pyrazol-1-yl)-5-ethylpyrimidine and a 4000-fold improvement of antiviral activity with a subnanomolar level of inhibition. Moreover, recent precedents in the literature describing antiviral derivatives acting at the level of the de novo pyrimidine biosynthetic pathway led us to determine that the mode of action of this series is based on the inhibition of the cellular dihydroorotate dehydrogenase (DHODH), the fourth enzyme of this pathway. Biochemical studies with recombinant human DHODH led us to measure IC50 as low as 13 nM for the best example of this original series when using 2,3-dimethoxy-5-methyl-6-(3-methyl-2-butenyl)-1,4-benzoquinone (coenzyme Q1) as a surrogate for coenzyme Q10, the cofactor of this enzyme.

Assessment of Salmonella and Listeria monocytogenes level in ready-to-cook poultry meat: effect of various high pressure treatments and potassium lactate concentrations

The objective of this study was to develop a probabilistic model in order to determine the contamination level of Salmonella and Listeria monocytogenes in ready-to-cook poultry meat, after a high pressure (HP) treatment. The model included four steps: i) Reception of raw meat materials, mincing and mixing meat, ii) Partitioning and packaging into 200-g modified atmosphere packs, iii) High pressure treatment of the meat, and iv) Storage in chilled conditions until the end of the shelf-life. The model excluded the cooking step and consumption at consumer's home as cooking practices and heating times are highly variable. The initial contamination level of Salmonella and L. monocytogenes was determined using data collected in meat primary processing plants. The effect of HP treatment and potassium lactate on microbial reduction was assessed in minced meat, using a full factorial design with three high pressure treatments (200, 350 and 500 MPa), three holding times (2, 8 and 14 min) and two potassium lactate concentrations (0 or 1.8% w/w). The inactivation curves fitted with a Weibull model highlighted that the inactivation rate was significantly dependent on the HP treatment. From the literature, it was established that Salmonella was not able to grow in the presence of lactate, under modified atmosphere and chilled conditions whereas the growth of L. monocytogenes was determined using an existing model validated in poultry (available in Seafood Spoilage and Safety Predictor software, V. 3.1). Once implemented in the Excel add-in @Risk, the model was run using Monte Carlo simulation. The probability distribution of contamination levels was determined for various scenarios. For an average scenario such as an HP treatment of 350 MPa for 8 min, of 200 g minced meat containing 1.8% lactate (pH 6.1; aw 0.96), conditioned under 50% CO2, the prevalence rate of Salmonella and L. monocytogenes, after a 20-day storage at 6 °C was estimated to be 4.1% and 7.1%, respectively. The contamination level was low considering that the product is going to be cooked by the consumer afterwards: the 99th percentile of the distribution was equal to -2.3log cfu/g for Salmonella and 0.5log cfu/g for L. monocytogenes. More generally, the model developed here from raw material reception up to the end of the shelf-life enables to recommend combinations of HP treatment and lactate formulation to guarantee an acceptable microbial concentration before cooking.

Establishing equivalence for microbial-growth-inhibitory effects ("iso-hurdle rules") by analyzing disparate listeria monocytogenes data with a gamma-type predictive model

Preservative factors act as hurdles against microorganisms by inhibiting their growth; these are essential control measures for particular food-borne pathogens. Different combinations of hurdles can be quantified and compared to each other in terms of their inhibitory effect ("iso-hurdle"). We present here a methodology for establishing microbial iso-hurdle rules in three steps: (i) developing a predictive model based on existing but disparate data sets, (ii) building an experimental design focused on the iso-hurdles using the model output, and (iii) validating the model and the iso-hurdle rules with new data. The methodology is illustrated with Listeria monocytogenes. Existing data from industry, a public database, and the literature were collected and analyzed, after which a total of 650 growth rates were retained. A gamma-type model was developed for the factors temperature, pH, a(w), and acetic, lactic, and sorbic acids. Three iso-hurdle rules were assessed (40 logcount curves generated): salt replacement by addition of organic acids, sorbic acid replacement by addition of acetic and lactic acid, and sorbic acid replacement by addition of lactic/acetic acid and salt. For the three rules, the growth rates were equivalent in the whole experimental domain (γ from 0.1 to 0.5). The lag times were also equivalent in the case of mild inhibitory conditions (γ ≥ 0.2), while they were longer in the presence of salt than acids under stress conditions (γ < 0.2). This methodology allows an assessment of the equivalence of inhibitory effects without intensive data generation; it could be applied to develop milder formulations which guarantee microbial safety and stability.

The moisturizing effect of a wheat extract food supplement on women's skin: a randomized, double-blind placebo-controlled trial

Ceramides, specific lipid components of the skin, represent 35-40% of the intercellular cement binding cells together and contributing to skin hydration. A wheat extract rich in ceramides and digalactosyl-diglycerides was developed by Hitex in two forms: wheat extract oil (WEO) and wheat extract powder (WEP). In vitro tests and two clinical studies demonstrated promising efficacy results with WEP on skin hydration. To confirm these early results, a double-blind, randomized, placebo-controlled study was carried out on 51 women aged 20-63 years with dry to very dry skin who received either 350 mg of WEO or placebo for 3 months. Evaluation of skin hydration on legs, arms and face, assessed at baseline (D0) and at study end (D84) was performed by the dermatologist using dermatological scores (dryness, roughness, erythema), skin hydration measurement (corneometry) and self-assessment scores (Visual Analogue Scale: VAS). Perceived efficacy was noted by participants throughout the study; tolerability and overall acceptability of the study products were evaluated by the dermatologist and the participants at the end of study. Skin hydration was significantly increased between D0 and D84 on the arms (P < 0.001) and legs (P = 0.012) in the WEO group compared with placebo. Even if no significant statistical differences between groups were observed for the dermatological evaluation, skin dryness and redness tended to be reduced in the WEO group. Moreover, from D0 to D84, the VAS index had a tendency to increase in favour of WEO for the overall skin hydration (P = 0.084) indicating that participants perceived an improvement. The WEO capsules were perceived by participants as being more effective than placebo on all skin dryness signs. In conclusion, WEO capsules were well tolerated and appreciated. After 3 months' treatment, a significant increase in skin hydration and an improvement in associated clinical signs were observed in women with dry skin.

5-Iodo-3-ethoxypyrazoles: an entry point to new chemical entities

Our program, which has focused on the preparation of new pyrazole derivatives, has led us to report here an original and simplified preparation of ethyl 3-ethoxy-1H-pyrazole-4-carboxylate. This is based on the reaction of hydrazine monohydrochloride and diethyl 2-(ethoxymethylene)malonate. Further transformations of this key compound allowed the preparation of the two possible iodinated isomers, namely, 3-ethoxy-4-iodo- and 3-ethoxy-5-iodo-1H-pyrazole. These compounds have opened the way to a quick access to many original pyrazole series. As an illustration, we report here on the selectivity of N-arylation, by using the Lam and Cham method, the C4- and C5-arylation of some of these 3-ethoxypyrazole derivatives by using the Suzuki-Miyaura reaction, and C5-benzylation reactions by means of the Negishi reaction. This was followed by hydrolysis of the ethoxy group, which led to the corresponding pyrazol-3-one derivatives. As a conclusion of this work, we conducted an investigation into the regiochemistry of the condensation between diethyl 2-(ethoxymethylene)malonate and the hydrochloride salts of methyl, benzyl, or phenyl hydrazine.