Publications by authors named "Seydoux J"

Background: LiCoO is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 °C) and long heating time (>24 h) to obtain the micronscale rhombohedral layered high-temperature phase of LiCoO (HT-LCO). Nanoscale HT-LCO is of interest to improve the battery performance as the lithium (Li) ion pathway is expected to be shorter in nanoparticles as compared to micron sized ones.

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  • Catch-up growth, linked to increased risk of type 2 diabetes, is marked by high insulin levels and rapid fat recovery following periods of food restriction.
  • In a rat study, refeeding on a high-fat diet was found to reduce the ability of adipose tissue to utilize glucose for fat production (de novo lipogenesis), leading to potential issues with glucose regulation.
  • The research supports the idea that dietary fats can disrupt normal glucose handling by promoting insulin resistance in muscles and reducing fat storage capabilities in fat tissue, contributing to glucose intolerance during catch-up growth.
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  • Obesity leads to chronic low-grade inflammation, which can negatively impact conditions like type 2 diabetes; anti-inflammatory approaches may help.
  • PI3Kγ is a key player in inflammation and insulin resistance, primarily functioning in immune cells and affecting processes like fat gain.
  • Mice without functional PI3Kγ are leaner due to increased energy expenditure and less fat gain, indicating that targeting PI3Kγ could be a new way to treat obesity and its related health issues.
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  • The study explores how different types of polyunsaturated fatty acids (PUFAs) affect fat accumulation and insulin levels during growth spurts on high-fat diets.
  • Rats fed diets high in linoleic acid (LA) or α-linolenic acid (ALA) showed better insulin sensitivity and lower fat mass when compared to those on low PUFA diets.
  • The research suggests that consuming PUFAs as 25-30% of energy intake can significantly improve body composition and insulin sensitivity, highlighting the benefits of LA and ALA over other fatty acids like arachidonic acid (AA) and DHA.
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We present the unusual case of a cytologically diagnosed Warthin tumor (WT) of long standing with sudden enlargement und subsequent resection. Histologically, the diagnosis of WT was confirmed, but the tumor additionally showed diffuse infiltrates of an adenocarcinoma undergoing unrestrained growth. Warthin tumor with malignant transformation was suspected and radiological staging examinations were conducted.

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  • The study focuses on "catch-up growth," a process linked to an increased risk of type 2 diabetes, particularly examining how glucose is used by fat cells during this phase.
  • Researchers used a rat model that simulates semistarvation followed by refeeding to study changes in fat tissue and glucose metabolism without increased food intake.
  • Results indicated that during catch-up fat, fat cells increase in number and change in composition, while hyperinsulinemia and enhanced fat-making processes (lipogenesis) occur early, suggesting these changes are crucial for storing glucose in fat rather than muscle.
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Recent advance in laparoscopy have changed the surgical approach of endometrial cancer patients. The Swissendos Center, Fribourg, in collaboration with AGO (Groupe de travail pour la gynécologie oncologique) and AGE (groupe de travail pour la gynécologie endoscopique) have established a consensus based on the available evidence for the use of laparoscopy in the management of patients with endometrial cancer The main objective was to define Swiss clinical practice guidelines appropriate to the country and consistent with the needs of the physicians.

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Energy conservation directed at accelerating body fat recovery (or catch-up fat) contributes to obesity relapse after slimming and to excess fat gain during catch-up growth after malnutrition. To investigate the mechanisms underlying such thrifty metabolism for catch-up fat, we tested whether during refeeding after caloric restriction rats exhibiting catch-up fat driven by suppressed thermogenesis have diminished skeletal muscle phosphatidylinositol-3-kinase (PI3K) activity or AMP-activated protein kinase (AMPK) signaling-two pathways required for hormone-induced thermogenesis in ex vivo muscle preparations. The results show that during isocaloric refeeding with a low-fat diet, at time points when body fat, circulating free fatty acids, and intramyocellular lipids in refed animals do not exceed those of controls, muscle insulin receptor substrate 1-associated PI3K activity (basal and in vivo insulin-stimulated) is lower than that in controls.

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The analyses of large epidemiological databases have suggested that infants and children who show catch-up growth, or adiposity rebound at a younger age, are predisposed to the development of obesity, type 2 diabetes and cardiovascular diseases later in life. The pathophysiological mechanisms by which these growth trajectories confer increased risks for these diseases are obscure, but there is compelling evidence that the dynamic process of catch-up growth per se, which often overlaps with adiposity rebound at a younger age, is characterized by hyperinsulinemia and by a disproportionately higher rate in the recovery of body fat than lean tissue (i.e.

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  • The study explores how weight loss and recovery can lead to increased fat storage, known as catch-up fat, due to decreased thermogenesis influenced by signals from fat tissue.
  • Researchers found that in a rat model of semistarvation followed by refeeding, levels of the gene SCD1 in skeletal muscle rise, linking this gene's activity to the process of fat recovery.
  • Elevated SCD1 levels help convert fatty acids, reducing their oxidation in mitochondria, which ultimately slows down the body’s energy expenditure and plays a role in regulating fat stores.
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Mice lacking beta-adrenoceptors, which mediate the thermogenic effects of norepinephrine and epinephrine, show diminished thermogenesis and high susceptibility to obesity, whereas mice lacking stearoyl-CoA desaturase 1 (SCD1), which catalyzes the synthesis of monounsaturated fatty acids, show enhanced thermogenesis and high resistance to obesity. In testing whether beta-adrenergic control of thermogenesis might be mediated via repression of the SCD1 gene, we found that in mice lacking beta-adrenoceptors, the gene expression of SCD1 is elevated in liver, skeletal muscle and white adipose tissue. In none of these tissues/organs, however, could a link be found between increased sympathetic nervous system activity and diminished SCD1 gene expression when thermogenesis is increased in response to diet or cold, nor is the SCD1 transcript repressed by the administration of epinephrine.

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Activation of the peroxisome proliferator-activated receptor (PPAR)-alpha increases lipid catabolism and lowers the concentration of circulating lipid, but its role in the control of glucose metabolism is not as clearly established. Here we compared PPARalpha knockout mice with wild type and confirmed that the former developed hypoglycemia during fasting. This was associated with only a slight increase in insulin sensitivity but a dramatic increase in whole-body and adipose tissue glucose use rates in the fasting state.

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The mechanisms by which CRH and related peptides (i.e. the CRH/urocortin system) exert their control over thermogenesis and weight regulation have until now focused only upon their effects on brain centers controlling sympathetic outflow.

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  • Catch-up growth is a process where rapid weight gain occurs, often leading to risks for obesity, type 2 diabetes, and cardiovascular diseases, characterized by high insulin levels and increased fat recovery.
  • A study using rat models found that during this catch-up growth, insulin was less effective in stimulating glucose use in muscles but more effective in fat tissues, indicating a shift in how the body processes glucose and fat.
  • The findings suggest that reduced body heat production (thermogenesis) may play a role in promoting fat recovery by causing insulin resistance in muscles and heightened insulin response in fat tissues, linking catch-up growth to future metabolic issues.
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After decades of controversies about the quantitative importance of autoregulatory adjustments in energy expenditure in weight regulation, there is now increasing recognition that even subtle variations in thermogenesis could, in dynamic systems and over the long term, be important in determining weight maintenance in some and obesity in others. The main challenge nowadays is to provide a mechanistic explanation for the role of adaptive thermogenesis in attenuating and correcting deviations of body weight and body composition, and in the identification of molecular mechanisms that constitute its effector systems. This workshop paper reconsiders what constitutes adaptive changes in thermogenesis and reassesses the role of the sympathetic nervous system (SNS) and uncoupling proteins (UCP1, UCP2, UCP3, UCP5/BMCP1) as the efferent and effector components of the classical one-control system for adaptive thermogenesis and fat oxidation.

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Life is a combustion, but how the major fuel substrates that sustain human life compete and interact with each other for combustion has been at the epicenter of research into the pathogenesis of insulin resistance ever since Randle proposed a 'glucose-fatty acid cycle' in 1963. Since then, several features of a mutual interaction that is characterized by both reciprocality and dependency between glucose and lipid metabolism have been unravelled, namely: the inhibitory effects of elevated concentrations of fatty acids on glucose oxidation (via inactivation of mitochondrial pyruvate dehydrogenase or via desensitization of insulin-mediated glucose transport),the inhibitory effects of elevated concentrations of glucose on fatty acid oxidation (via malonyl-CoA regulation of fatty acid entry into the mitochondria), and more recentlythe stimulatory effects of elevated concentrations of glucose on de novo lipogenesis, that is, synthesis of lipids from glucose (via SREBP1c regulation of glycolytic and lipogenic enzymes). This paper first revisits the physiological significance of these mutual interactions between glucose and lipids in skeletal muscle pertaining to both blood glucose and intramyocellular lipid homeostasis.

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  • Researchers studied how leptin affects respiration rates in mouse skeletal muscle and its interaction with metabolism using specific enzymes like PI3K and AMPK.
  • *The findings indicate that leptin boosts heat production in muscle by promoting a cycle between fat production and fat burning, which relies on both PI3K and AMPK signaling pathways.
  • *This process helps prevent excessive fat buildup in skeletal muscle, offering a new understanding of how leptin contributes to metabolic health.
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The peroxisome proliferator-activated receptor gamma (PPARgamma) plays a major role in fat tissue development and physiology. Mutations in the gene encoding this receptor have been associated to disorders in lipid metabolism. A thorough investigation of mice in which one PPARgamma allele has been mutated reveals that male PPARgamma heterozygous (PPARgamma +/-) mice exhibit a reduced body size associated with decreased body weight, reflecting lean mass reduction.

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The ability of a retinoid X receptor (RXR) to heterodimerize with many nuclear receptors, including LXR, PPAR, NGF1B and RAR, underscores its pivotal role within the nuclear receptor superfamily. Among these heterodimers, PPAR:RXR is considered an important signalling mediator of both PPAR ligands, such as fatty acids, and 9-cis retinoic acid (9-cis RA), an RXR ligand. In contrast, the existence of an RXR/9-cis RA signalling pathway independent of PPAR or any other dimerization partner remains disputed.

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To assess the role of the alpha1b-adrenergic receptor (AR) in glucose homeostasis, we investigated glucose metabolism in knockout mice deficient of this receptor subtype (alpha1b-AR-/-). Mutant mice had normal blood glucose and insulin levels, but elevated leptin concentrations in the fed state. During the transition to fasting, glucose and insulin blood concentrations remained markedly elevated for at least 6 h and returned to control levels after 24 h whereas leptin levels remained high at all times.

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We investigated, in skeletal muscle mitochondria isolated from semistarved and refed rats, the relation between the protein expression of uncoupling protein 3 (UCP3) and mitochondrial oxidative capacity, assessed as state 4 and state 3 respiration rates in presence of substrates that are either non-lipids (glutamate, succinate) or lipids (palmitoyl CoA, palmitoylcarnitine). During semistarvation, when whole-body thermogenesis is diminished, state 3 respiration was lower than in fed controls by about 30% independently of substrate types, while state 4 respiration was lower by 20% only during succinate oxidation, but UCP3 was unaltered. After 5 days of refeeding, when thermogenesis is still diminished, neither state 4, state 3 nor UCP3 were lower than in controls.

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