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Search Results: 1 - 10 of 75 matches for " Corine Bayourthe "
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A Bioenergetic-Redox Approach to the Effect of Live Yeast on Ruminal pH during Induced Acidosis in Dairy Cow  [PDF]
Jean Philippe Marden, Corine Bayourthe, Eric Auclair, Raymond Moncoulon
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.410A1008
Abstract: The objective of this study was to evaluate the capacity of the live yeast (LY) Saccharomyces cerevisiae in optimizing ruminal pH and in understanding its mode of action during induced acidosis in dairy cow. Two non-lactating cannulated cows were used and offered twice daily a control diet (CD) consisting of 51% corn silage and 49% concentrates or a LY diet (LYD) composed of CD supplemented with 4 g of LY per cow and per day. Measurements of pH and redox potential (Eh) were continuously made at 1 h interval during an experimental period of 9 h per day. Samples of ruminal fluid were also taken at 2 h intervals for analyses of volatile fatty acids (VFA) and lactic acid. Oxygen partial pressure (logPO2) in the ruminal milieu was calculated from the Nernst equation, using either O2-H2O or lactate-propionate redox couples. The results showed an increase of 0.2 unit in ruminal pH when LYD was fed, which was accompanied by a mean difference in Eh of -20 mV with respect to CD. The logPO2 decreased significantly by 0.8 log unit for LYD when compared to CD. Concentrations of VFA and proportion of propionate were higher with LYD (114.4 mM and 17.1% total VFA) compared to CD (102.4 mM and 15.4% total VFA). Proportion of butyrate
Effects of Feeding Programs Based on One or Two Milk Replacer Daily Meals on Growth, Solid Feed Intake and Rumen Fermentation and Development of Dairy Calves  [PDF]
Christine Julien, Corine Bayourthe, Caroline Lacroux, Francis Enjalbert
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.612139
Abstract: Sixteen Holstein calves were used to study the effects of two feeding programs (FP) on growth, intake, rumen development and ruminal metabolism from birth to weaning. Two feeding programs based on milk replacer (MR) were tested: a once a day (OAD) MR (200 g/L) distribution vs. a standard twice a day (TAD) MR (125 g/L) distribution. All calves received water, wheat straw and a starter concentrate ad libitum. Four calves per group were slaughtered at weaning and rumen epithelium from the ventral sac was sampled for papillae (RP) density. Results showed that the FP had no effect on body weight of calves and total feed intake. From day 42 to day 56, ruminal pH was lower (P = 0.036) and ruminal oxydo-reducing potential was higher (P = 0.001) in OAD than TAD calves. Ruminal total volatile fatty acid (VFA) concentrations did not significantly differ between FP. From day 21 to day 63, butyrate ruminal concentration was significantly higher in OAD than TAD calves (5.17 vs 3.95 mmol/L). This probably explained the higher development of RP in calves fed once daily. Finally, the tested feeding system based on a once daily MR distribution affects the concentrate feeding pattern of calves.
Methodology Article: Can Ruminal Reducing Power Assessed in Batch Cultures be Comparable to in Vivo Measurements?  [PDF]
Christine Julien, Jean-Philippe Marden, Annabelle Troegeler-Meynadier, Corine Bayourthe
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2014, DOI: 10.4236/jasmi.2014.43011
Abstract:

In ruminant field of digestive research, the appeal to methods of less invasive studies and reproducing the in vivo conditions is essential. The objective of the present study was to determine whether the conditions created with the proposed in vitro batch culture was an accurate reproduction of the physico-chemical and fermentative ruminal conditions observed in vivo. Two experiments were conducted to compare ruminal reducing power measured in vitro, i.e. in batch cultures or, in vivo i.e. in live animals: dairy cows at maintenance (Experiment 1) and lactating dairy cows (Experiment 2). In Experiment 1, at the beginning of incubation period, in vitro redox potential (Eh), pH and Clark’s exponent (rH) values were significantly higher than in vivo (+42 mV, +0.25 and +1.9, respectively) whereas volatile fatty acids (VFA)

Interaction between Live Yeast and Dietary Rumen Degradable Protein Level: Effects on Diet Utilization in Early-Lactating Dairy Cows  [PDF]
Christine Julien, Jean Philippe Marden, Eric Auclair, Raymond Moncoulon, Laurent Cauquil, Jean Louis Peyraud, Corine Bayourthe
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.61001
Abstract: Four early lactating Holstein cows were used to study the effect of live yeast (LY, Actisaf® CNCM I-4407, Lesaffre Feed Additives, Marcq en Baroeul, France) supplementation on diet digestive utilization of dairy cows receiving concentrated corn silage-based diets with two rumen-degradable protein (RDP) levels. For a 33 d period, cows were fed a total mixed ration (TMR) containing an adequate level (AL) of RDP or a low level (LL, 30% below AL) by using soybean meal or tanned soybean meal, respectively: for 21 d with no LY addition followed by 12 d during which LY was added to the diet. The pH and redox potential (Eh) were recorded and ruminal fluid samples were collected over 3 consecutive days. Feces were collected individually over 48 h and individual dry matter intake (DMI) was measured for determining apparent nutrient digestibility. The effective degradability of individual feed ingredients composing both diets was evaluated with nylon bags technique. Structure of the ruminal bacterial community was studied and diversity index was calculated. Digestibility of organic matter (OM) and crude protein (CP) were lower for LL than those for AL. With LY, digestibility of OM and CP was increased: +2.4 and +0.8 points, for AL, and +3.7 and +5.9 points for LL, respectively. Live yeast reduced dietary N ruminal degradation with both AL and LL. Ruminal pH and Eh were lower with AL compared to LL: 5.95 and –167 mV vs. 6.13 and –144 mV. Live yeast increased ruminal total volatile fatty acids (VFA) (+8.6%), C2 (+10%), and C4 (+35%) contents for LL and decreased that of C3 (?9.8%) for AL. Neither the structure of bacterial populations of the rumen nor the diversity index (Shannon) was altered by treatments. Those results suggested a specific interest in using LY in RDP deficient diets for early lactating cows.
Quantitative Analysis of the Relationship between Ruminal Redox Potential and pH in Dairy Cattle: Influence of Dietary Characteristics  [PDF]
Yayu Huang, Jean Philippe Marden, Chaouki Benchaar, Christine Julien, Eric Auclair, Corine Bayourthe
Agricultural Sciences (AS) , 2017, DOI: 10.4236/as.2017.87047
Abstract: The ruminal redox potential (Eh) can reflect the microbiological activity and dynamics of fermentation in the rumen. It might be an important indicator of rumen fermentation in combination with pH. However, the ruminal Eh has been rarely studied in dairy cows due to the difficulty of its measurement, and the relationship between ruminal Eh and pH is not clear. The objective of this study was to investigate the relationship between ruminal Eh and pH of dairy cows by meta-analysis of systematic measurements from different experiments. A database was constructed from 22 experiments on cannulated dairy cattle including 57 dietary treatments. The ruminal pH and Eh were measured without air contact between 0 and 8 h post-feeding. The results demonstrated a quadratic correlation between ruminal Eh and pH with a reliable within-animal variation (Eh = -1697 + 540.7 pH -47.7 pH2, nobservation = 70, nanimal = 26, P < 0.001, RMSE = 56, AIC = 597). The dietary characteristics (NDF, NDFf, OM, starch, degradable starch, soluble sugars contents, and the dietary ionic balance) influencing the ruminal pH also affected the ruminal Eh, but not always to the same extent. Some of them still influenced the relationship between ruminal Eh and pH. While the mechanism of the interaction between ruminal Eh and pH remains to be elucidated, it would be interesting to associate Eh to microbial profile, ruminal VFA concentration and milk production performance in future studies.
Understanding the Logical Constants and Dispositions
Corine Besson
The Baltic International Yearbook of Cognition, Logic and Communication , 2010, DOI: 10.4148/biyclc.v5i0.279
Abstract: Many philosophers claim that understanding a logical constant (e.g. ‘if, then’) fundamentally consists in having dispositions to infer according to the logical rules (e.g. Modus Ponens) that fix its meaning. This paper argues that such dispositionalist accounts give us the wrong picture of what understanding a logical constant consists in. The objection here is that they give an account of understanding a logical constant which is inconsistent with what seem to be adequate manifestations of such understanding. I then outline an alternative account according to which understanding a logical constant is not to be understood dispositionally, but propositionally. I argue that this account is not inconsistent with intuitively correct manifestations of understanding the logical constants.
Melanoma: From Melanocyte to Genetic Alterations and Clinical Options
Corine Bertolotto
Scientifica , 2013, DOI: 10.1155/2013/635203
Abstract: Metastatic melanoma remained for decades without any effective treatment and was thus considered as a paradigm of cancer resistance. Recent progress with understanding of the molecular mechanisms underlying melanoma initiation and progression revealed that melanomas are genetically and phenotypically heterogeneous tumors. This recent progress has allowed for the development of treatment able to improve for the first time the overall disease-free survival of metastatic melanoma patients. However, clinical responses are still either too transient or limited to restricted patient subsets. The complete cure of metastatic melanoma therefore remains a challenge in the clinic. This review aims to present the recent knowledge and discoveries of the molecular mechanisms involved in melanoma pathogenesis and their exploitation into clinic that have recently facilitated bench to bedside advances. 1. The Melanocytes: From Photoprotection to Cancer 1.1. Melanocyte Development Melanoblasts undifferentiated and unpigmented precursors migrate from the neural crest to their final destination, the epidermis and hair follicles, where they differentiate and become mature melanocytes able to synthesize and transfer melanin pigment to neighbouring keratinocytes (Figure 1). Melanocytes are also found in the stria vascularis of the inner ear cochlea where they are involved in the production of endolymph along with ion exchange essential for hearing. Melanocytes are also located in the iris and in the choroid where pigments are involved in the formation, behind the retina, of the darkroom, which is necessary for the vision. This review will focus on cutaneous melanocytes only. Figure 1: General overview of melanocyte physiology. Melanocytes derived from the neural crest in the form of undifferentiated and unpigmented precursors, the melanoblasts, migrate to their final destination, the epidermis, where they synthesize melanin in melanosomes. Pax3, Sox10, endothelin3 (ED-3) and its receptor (Endrb), c-Kit and Mitf play a critical role in the development of melanocytes. Melanin is then transferred to neighboring keratinocytes to ensure skin protection against the deleterious effect of ultraviolet radiation. During embryogenesis, the survival and migration of melanocytes rely on signaling pathways such as Wingless signaling (Wnt)/ -catenin, the endothelin B receptor and its ligand endothelin-3, the receptor tyrosine kinase KIT and its ligand KIT-ligand/SCF (stem cell factor), NOTCH [1, 2], and transcription factors activity such as paired box gene 3 (PAX3), SRY (sex-determining
Nanotrend : studying nano-districts gives a new view on nanoscience
Corine Genet
Physics , 2009,
Abstract: The emergence of districts in nanotechnology represents a new pattern of scientific development. The factors affecting their growth are analysed to understand the drivers of economic development. By analyzing the top 200 nano-districts, Nanotrendchart sheds light on the clusterization process: academic production is seen to be highly concentrated, with fifteen districts representing over half of published articles; Asian districts are clearly growing significantly faster than those elsewhere; and district growth in the domain of engineering and physics is more rapid than in other disciplines. Scientific diversity, actors diversity as well as the degree of openness of the cluster influence their evolution. Highly specialised clusters witness lower growth rates
SAMHD1: a new insight into HIV-1 restriction in myeloid cells
Corine St Gelais, Li Wu
Retrovirology , 2011, DOI: 10.1186/1742-4690-8-55
Abstract: Myeloid-lineage cells, including monocytes, dendritic cells (DCs) and macrophages, play a multifaceted role in HIV-1 initial infection and viral dissemination; however, these cell types are restrictive to post-entry HIV-1 infection in vitro [1,2]. For gene therapy purposes, transduction of human DCs with an HIV-1-derived lentiviral vector can be significantly enhanced by preincubation with virus-like particles derived from SIV [3]. Subsequent studies indicated that Vpx proteins from sooty mangabey SIV (SIVsm) and HIV-2 lineages efficiently enhance HIV-1 infection in human DCs and promote the accumulation of full-length viral DNA [4]. Further studies from several laboratories suggested that Vpx, similar to HIV-1 Vpr, interacts with the DCAF1 component of the CUL4A/DDB1 and E3 ubiquitin ligase complex (reviewed in [5,6]). However, only SIVsm/HIV-2 Vpx can efficiently enhance HIV-1 infection in DCs and macrophages [5]. These studies led to the hypothesis that Vpx targets a putative HIV-1 restriction factor for proteasomal degradation in myeloid cells through the E3 ubiquitin ligase complex [5,6], prompting the search for the unknown HIV-1 restriction factor in human myeloid cells that is counteracted by Vpx.SIVsm, SIVsm-derived rhesus macaque SIV (SIVmac), and HIV-2 encode both Vpr, a homologue of the HIV-1 Vpr protein, and Vpx, a protein unique to the SIVsm lineage. vpx has likely evolved via duplication of the primate lentivirus vpr gene [5]. Early studies have demonstrated that macaques infected with Vpx-defective SIVmac or SIVsm had decreased viremia, impaired viral replication, and slower AIDS progression compared to wild-type SIV-infected animals, thus revealing the importance of Vpx in SIV pathogenesis [7,8]. The important role of Vpx in lentiviral infection in myeloid-lineage cells in vitro and in vivo indicates that Vpx is not merely a functional copy of Vpr, but may possess a unique function. Although Vpx has been reported to facilitate nuclear import of vira
The competing faces of mental health law: Recovery and access versus the expanding use of preventive confinement
John Petrila,Corine de Ruiter
Amsterdam Law Forum , 2011,
Abstract:
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