Centre Nantais de Sociologie

This paper examines buyers’ preferences for quality in French first-sale fish markets. Using data covering 72 million transactions between 2011 and 2022, we first estimate quality premiums with an exact matching procedure that controls for product availability. We then apply interval regression models to explain differences in buyers’ willingness-to-pay for high-quality fish. Results show substantial heterogeneity in quality premiums across both lots and species. Econometric estimates further reveal that quality premiums decline with lot size and vary with buyer characteristics. Retailers and supermarkets pay more for high-quality fish, while wholesalers, processors, and canners are less sensitive to quality. These findings highlight how value from quality is distributed along the supply chain and which types of buyers capture it. • High-quality fish commands significant price premiums at first-sale markets • Premiums vary across fish species and transaction lots • Willingness-to-pay for quality declines with lot size • Retailers and supermarkets pay larger premiums than wholesalers and processors • Results show where value from quality is captured along the supply chain

ABSTRACTPatients with chronic kidney disease, and particularly those under hemodialysis, are prone to develop cardiovascular complications, mostly due to the exacerbation of vascular calcification. Vascular calcification relies on the transdifferentiation of vascular smooth muscle cells into calcifying cells. Sphingosine 1‐phosphate is a pleiotropic sphingolipid and an important regulator of osteogenesis and the cardiovascular system. Therefore, we explored the role of sphingosine 1‐phosphate metabolism in chronic kidney disease‐derived vascular calcification. Vascular calcification progression in chronic kidney disease and sphingosine 1‐phosphate signaling were examined in calcified vascular smooth muscle cells, in aortic explants, in rats with adenine‐induced chronic kidney disease, as well as in serum from hemodialysis patients. Sphingosine kinase 2 activity and sphingosine 1‐phosphate secretion, under the control of phospholipase D1, were exacerbated in calcified vascular smooth muscle cells. Furthermore, phospholipase D1 knockout mice display significantly less circulating sphingosine 1‐phosphate, supporting intertwined signalization cascades. Overall, sphingosine kinase expression and activity were upregulated in calcified aortic explants and in calcified aortas from rats. Sphingosine 1‐phosphate was increased in the serum of rats with mild vascular calcification. The Food and Drug Administration‐approved immunosuppressant drug fingolimod, a general modulator of S1P metabolism, strongly inhibited calcification in vascular smooth muscle cells and aortic explants. Additionally, fingolimod significantly reduced inflammation, attenuated metabolic syndrome and moderately inhibited aortic calcification in rats. Finally, we demonstrated for the first time that serum sphingosine 1‐phosphate was significantly increased in hemodialysis patients with mild abdominal aortic calcification. Our findings open an unexplored therapeutic option, which is targeting sphingosine 1‐phosphate metabolism, eventually with fingolimod, for the prevention and treatment of vascular calcification in chronic kidney disease patients.

The complexity of scRNA-sequencing datasets highlights the urgent need for enhanced clustering and visualization methods. Here, we propose Stardust, an iterative, force-directed graph layout algorithm that enables the simultaneous embedding of cells and marker genes. Stardust, for the first time, allows a single-stop visualization of cells and marker genes on a single 2D map. While Stardust provides its own visualization pipeline, it can be plugged in with state-of-the-art methods such as Uniform Manifold Approximation and Projection (UMAP) and t-Distributed Stochastic Neighbor Embedding (t-SNE). We benchmarked Stardust against popular visualization and clustering tools on both scRNA-seq and spatial transcriptomics datasets. In all cases, Stardust performs competitively in identifying and visualizing cell types in an accurate and spatially coherent manner.

The health impact of dairy products is debated due to their high saturated fatty acid (SFA) content. Emerging evidence suggests that dairy products intake may reduce cardiovascular disease risk, despite their SFA-rich lipids, leading to the "dairy food matrix" concept. Nevertheless, the impact of lipid and SFA intake from whole dairy sources on cardio-metabolic health remains poorly understood. This study investigated the cross-sectional association of SFA intake from various types of dairy products and dairy fat sources with cardio-metabolic outcomes. Data from 1619 participants of the STANISLAS cohort, who underwent extensive metabolic and cardiovascular phenotyping and completed a 133-item food frequency questionnaire covering dairy products and other dairy fat sources, were used. Associations of total dietary lipid, total dietary SFA, and SFA intakes from dairy products and dairy fat sources with metabolic outcomes (metabolic syndrome, hyperlipidemia, type 2 diabetes, prediabetes) and subclinical cardiovascular damages (i.e., arterial stiffness, atherosclerosis, left ventricular mass, diastolic dysfunction) were assessed using mixed models. Median [interquartile range] lipid consumption via dairy products and dairy fat sources was 23 [15, 34] g/day. Higher total dietary lipid intake was associated with lower arterial stiffness (exp(β) [95%CI]: 0.96 [0.92-0.99]). Total dietary SFA and SFA from dairy products were both inversely associated with left ventricular mass (exp(β) [95%CI]: 0.85 [0.74-0.98], and 0.99 [0.99-0.99], respectively). SFA from dairy fat sources, particularly from Butter, were inversely associated with hyperlipidemia (OR [95%CI]: 0.96 [0.93-0.99] for hypertriglyceridemia, 0.96 (0.93-0.99) for elevated LDLc, 0.95 (0.92-0.98) for elevated non-HDLc, 0.93 (0.89-0.96) for elevated Apolipoprotein B). SFA from Yogurt was inversely associated with Apolipoprotein B (OR [95%CI]: 0.92 [0.86-0.98]). Examining the specific diary matrix subtypes, our results suggest altogether neutral to beneficial associations of SFA from dairy products and dairy fat sources with cardio-metabolic health.

• We study the link between food insecurity and health among food assistance recipients. • Food insecurity and poor health are strongly and positively correlated in France. • The food insecurity-poor health correlation is stronger among natives than immigrants. • The low frequency of food center visits may explain why food insecurity affects health. This paper examines the relationship between food insecurity and poor health among food assistance recipients in France using a dataset collected in 2021 from nearly 4,000 respondents. For these individuals from disadvantaged socio-economic backgrounds, food assistance may eliminate the association between food insecurity and health reported in surveys of the general population. Regression estimates show a strong positive association between food insecurity and poor health (self-reported health, chronic disease, activity limitation). This correlation is significantly higher for native respondents than for migrants. After accounting for the endogeneity of food insecurity through a free-instrument approach that estimates bounds, we confirm the positive association between food insecurity and poor health. The low frequency of visits to food banks may explain why food insecurity persists among participants and continues to affect health.

L’idée que la grossesse puisse être formalisée par un calendrier spécifique, séquencé en mois et en trimestres, marqué par des seuils (seuil des 3 mois, période de réalisation des échographies, seuil de viabilité du fœtus, etc.) et délimité par une prévision de l’accouchement au jour près semble aujourd’hui aller de soi. Cet article interroge cette évidence en examinant la mise en nombre du temps de la grossesse sous l’angle de la quantification telle qu’elle a été définie par A. Desrosières : quelles sont les conventions qui président à la quantification du temps de la grossesse ? Quelles en sont les logiques sous-jacentes ? Quels sont les effets de ces opérations de quantification ? À partir d’une enquête qualitative menée dans deux maternités hospitalières franciliennes et d’une étude de la littérature secondaire, l’article retrace la généalogie de la mise en nombre de la grossesse depuis le début du xxe siècle et son évolution, puis il analyse le caractère normatif de cette quantification, ainsi que ses effets sociaux. Cette quantification repose, comme le révèle l’examen des conventions qui la sous-tendent, sur l’idée que l’ovulation est le premier jour de « vie » d’un individu-fœtus, qui constitue l’objet principal du parcours de soin. De plus, la mise en nombre du temps de la grossesse aboutit à sa standardisation, qui s’impose dans les pratiques, jusqu’à intervenir sur les processus physiologiques.

International audience