Jean Demarquoy

• PhD
• Professor at Université Bourgogne Europe

The recent study exploring the bidirectional associations between gallstone disease, non-alcoholic fatty liver disease, and kidney stone disease highlights a critical concern in chronic disease management. Given the rising global prevalence of these conditions, understanding their interconnections is essential. The study emphasizes the importance o...

L-Carnitine, sourced from red meat, dairy, and endogenous synthesis, plays a vital role in fatty acid metabolism and energy production. While beneficial for cardiovascular, muscular, and neural health, its interaction with the gut microbiota and conversion into trimethylamine (TMA) and trimethylamine N-oxide (TMAO) raise concerns about heart health...

Gout, recognized as the most common form of inflammatory arthritis, arises from the accumulation of uric acid crystals, leading to intense pain, particularly in the big toe. This condition has traditionally been associated with the overproduction or reduced clearance of uric acid. Recent studies, however, have underscored the significant role of th...

This editorial explores the intricate relationship between microplastics (MPs) and gut microbiota, emphasizing the complexity and environmental health implications. The gut microbiota, a crucial component of gastrointestinal health, is examined in the context of potential microbial degradation of MPs. Furthermore, dysbiosis induced by MPs emerges a...

The gut microbiota and dysbiosis have been implicated in various metabolic diseases and gastrointestinal disorders. Recently, there has been growing evidence suggesting the influence of gut microbiota on neurological disorders, including autism. Although the number of children diagnosed with autism is increasing, the exact cause of the disease rema...

Unbalanced energy partitioning participates in the rise of obesity, a major public health concern in many countries. Increasing basal energy expenditure has been proposed as a strategy to fight obesity yet raises efficiency and safety concerns. Here, we show that mice deficient for a muscle-specific enzyme of very-long-chain fatty acid synthesis di...

Introduction L’Anses présente un état des connaissances sur les dangers liés aux champs électromagnétiques basses fréquences (CEM-BF) et les résultats de son expertise collective concernant les risques pour la santé liés aux expositions en milieu professionnel. Matériel et méthodes Ce travail est fondé sur l’analyse des données de la littérature s...

The tubular shape of mitochondrial cristae depends upon a specific composition of the inner mitochondrial membrane, including cardiolipin that allows strong curvature and promotes optimal organization of ATP synthase. Here we identify Hacd1, which encodes an enzyme involved in very long chain fatty acid biosynthesis, as a key regulator of compositi...

AIM To identify and characterize the protective effect that L-carnitine exerted against an oxidative stress in C2C12 cells. METHODS Myoblastic C2C12 cells were treated with menadione, a vitamin K analog that engenders oxidative stress, and the protective effect of L-carnitine (a nutrient involved in fatty acid metabolism and the control of the oxi...

Mitochondria and peroxisomes are small ubiquitous organelles. They both play major roles in cell metabolism, especially in terms of fatty acid metabolism, reactive oxygen species (ROS) production, and ROS scavenging, and it is now clear that they metabolically interact with each other. These two organelles share some properties, such as great plast...

The reduced diameter of skeletal myofibres is a hallmark of several congenital myopathies, yet the underlying cellular and molecular mechanisms remain elusive. In this study, we investigate the role of HACD1/PTPLA, which is involved in the elongation of the very long chain fatty acids, in muscle fibre formation. In humans and dogs, HACD1 deficiency...

N-3 polyunsaturated long chain fatty acids and especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are known to limit inflammation and to improve its resolution. The benefits resulting from the use of EPA and DHA are numerous, they are used for treating asthma and arthritis, for controlling blood pressure and vascular reactivity a...

Duchenne muscular dystrophy (DMD) arises as a consequence of mutations in the dystrophin gene. Dystrophin is a membrane-spanning protein that connects the cytoskeleton and the basal lamina. The most distinctive features of DMD are a progressive muscular dystrophy, a myofiber degeneration with fibrosis and metabolic alterations such as fatty infiltr...

Nucleotide sequences of the primers used for Q-PCR. The sequences are presented 5′–3′ and from left to right the forward and the reverse primer. (DOCX)

Fatty acid profile of the PL extracted from membranes of control and patient cells. The content for each fatty acid was determined and expressed in percent of the total amount of fatty acids. Those values represent the raw data used for making Table 1. Each number is the average of 7 independent experiments ± sem. (DOCX)

L-carnitine is a key molecule in both mitochondrial and peroxisomal lipid metabolisms. L-carnitine is biosynthesized from gamma-butyrobetaine by a reaction catalyzed by the gamma-butyrobetaine hydroxylase (Bbox1). The aim of this work was to identify molecular mechanisms involved in the regulation of L-carnitine biosynthesis and availability. Using...

Fatty acids are known to serve as energetic substrates, key components of membrane lipids, and as substrates for the synthesis of signaling molecules and complex lipids. They are also known to be ligands either of membrane receptors involved in cell signaling or of nuclear receptors mediating gene regulation. Accumulation of fatty acids due to alte...

Resveratrol is one of the best known polyphenol. While its effect on endothelial blood vessel cells, cancer cells, inflammatory processes and neurodegenerative events is well documented, only little is established on the metabolic implication of this phytophenol, particularly on skeletal muscle cells. Here, we report the effect of resveratrol on mo...

In Alzheimer's disease (AD) and dementia of the Alzheimer's type (DAT), the role played by peroxisomes is not well known. Peroxisomes are present in all eukaryotic cells, with the exception of erythrocytes. They are involved in the β-oxidation process of long-chain fatty acids, very-long-chain fatty acids, and branched-chain fatty acids. They parti...

In Alzheimer's disease (AD) and dementia of the Alzheimer's type (DAT), the role played by peroxisomes is not well known. Peroxisomes are present in all eukaryotic cells, with the exception of erythrocytes. They are involved in the β-oxidation process of long-chain fatty acids, very-long-chain fatty acids, and branched-chain fatty acids. They parti...

Peroxisomes and mitochondria are ubiquitously found organelles. They both are dynamic structures able to divide, to fuse and to undergo autophagic processes. Their activities are dependent on proteins that are, for most (mitochondria) or all (peroxisome) of them, synthesized in the cytosol from the nuclear genome. Nevertheless, the membrane structu...

The peroxisomal beta oxidation of very long chain fatty acids (VLCFA) leads to the formation of medium chain acyl-CoAs such as octanoyl-CoA. Today, it seems clear that the exit of shortened fatty acids produced by the peroxisomal beta oxidation requires their conversion into acyl-carnitine and the presence of the carnitine octanoyltransferase (CROT...

l ‐carnitine is found in nearly all living cells. l ‐carnitine present in human body can be either provided by a biosynthetic pathway or by food. Carnitine plays a major role in lipid and energy metabolism. In the human body, the primary role of l ‐carnitine is to shuttle long‐chain fatty acids into the mitochondria where they are used to produce e...

In mammals, during the aging process, an atrophy of the muscle fibers, an increase in body fat mass, and a decrease in skeletal muscle oxidative capacities occur. Compounds and activities that interact with lipid oxidative metabolism may be useful in limiting damages that occur in aging muscle. In this study, we evaluated the effect of L-carnitine...

L ‐Carnitine plays an important role in skeletal muscle bioenergetics, and its bioavailability and thus its import may be crucial for muscle function. We studied the effect of thyroid hormone, insulin, and iron overload, hormones and nutrients known to alter muscle metabolism, on L ‐carnitine import into C2C12 cells. We report here L ‐carnitine upt...

L-carnitine is an essential cofactor for the transport of fatty acids across the mitochondrial membranes. L-carnitine can be provided by food products or biosynthesized in the liver. After intestinal absorption or hepatic biosynthesis, L-carnitine is transferred to organs whose metabolism is dependent upon fatty acid oxidation, such as the skeletal...

Human adults store around 20g of l-carnitine. In the human body, l-carnitine is not metabolized but excreted through the kidney. Lost l-carnitine has to be replenished either by a biosynthetic mechanism or by the consumption of foods containing l-carnitine. Today, there is no "official" recommended daily allowance for l-carnitine but the daily need...

Extracellular ATP regulates cell proliferation, muscle contraction and myoblast differentiation. ATP present in the muscle interstitium can be released from contracting skeletal muscle cells. L-Carnitine is a key element in muscle cell metabolism, as it serves as a carrier for fatty acid through mitochondrial membranes, controlling oxidation and en...

Ghrelin is a 28-amino-acid peptide secreted during starvation by gastric cells. Ghrelin physiologically induces food intake and seems to alter lipid and glucid metabolism in several tissues such as adipose tissue and liver. Liver has a key position in lipid metabolism as it allows the metabolic orientation of fatty acids between oxidation and ester...

Gamma-butyrobetaine hydroxylase (BBOX1) is the enzyme responsible for the biosynthesis of l-carnitine, a key molecule of fatty acid metabolism. This cytosolic dimeric protein belongs to the dioxygenase family. In human, enzyme activity has been detected in kidney, liver and brain. The human gene encoding gamma-butyrobetaine hydroxylase is located o...

Experimental evidence indicates that n-3 fatty acids, especially the long-chain polyunsaturated fatty acids, unlike n-6 fatty acids could prevent cancer development. This survey shows that fatty acids could act through several mechanisms including the production of reactive oxygen species, the modulation of gene expression and signal transduction p...

l-Carnitine is a vitamin-like nutrient essential for energy production and lipid metabolism in many organs and tissues such as skeletal muscle and heart. Even if l-carnitine can be synthesized, most of the carnitine present in human body is provided by food. Until now, no large study has been conducted where the content in l-carnitine of various fo...

Aim. – The goal of this study was to clarify the precise role of carnitine in the normal function of muscle cell and to determine the rational for carnitine suplementation in improving physical performance.Recent data. – Recently, new data have been reported concerning the biosynthetic pathway for carnitine as well as its intracellular transport ac...

L-Carnitine is a key molecule in the transfer of fatty acid across mitochondrial membranes. Bioavailable L-carnitine is either provided by an endogeneous biosynthesis or after intestinal absorption of dietary items containing L-carnitine. After intestinal absorption or hepatic biosynthesis, L-carnitine is transferred to organs whose metabolism is d...

The carnitine system plays a key role in beta-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on gamma-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased...

Carnitine is involved in the transfer of fatty acids across mitochondrial membranes. Carnitine is found in dairy and meat products, but is also biosynthesized from lysine and methionine via a process that, in rat, takes place essentially in the liver. After intestinal absorption or hepatic biosynthesis, carnitine is transferred to organs whose meta...

Carnitine biosynthesis from lysine and methionine involves five enzymatic reactions. gamma-butyrobetaine hydroxylase (BBH; EC 1.14. 11.1) is the last enzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma-butyrobetaine to carnitine. The cDNA encoding this enzyme has been isolated and characterized. The cDNA contained an open re...

The five-fold higher carnitine content in the liver of fenofibrate-treated rats addresses the question about the possible role of this enhancement in the hypolipidaemic effect of the drug and the underlying mechanisms. When fenofibrate was administered with mildronate (a gamma-butyrobetaine hydroxylase inhibitor) in suitable amount, the content in...

The biosynthesis of carnitine from lysine and methionine involves five enzymatic reactions. Gamma-butyrobetaine hydroxylase (BBH; EC 1.14.11.1) is the last enzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma-butyrobetaine to carnitine. This enzyme had never been purified to homogeneity from rat tissue. This paper describes t...

This study was designed to determine which enzyme activities were first impaired in mitochondria exposed to 2,2'-azobis-(2-amidinopropane) dihydrochloride (AAPH), a known radical initiator. EPR spin-trapping revealed generation of reactive oxygen species although malondialdehyde formation remained very low. With increasing AAPH concentrations, Stat...

This study was designed to examine whether short- and long-term treatments by a low level of dietary L-carnitine are capable of altering enzyme activities related to fatty acid oxidation in normal Wistar rats. Under controlled feeding, ten days of treatment changed neither body weights nor liver and gastrocnemius weights, but succeeded in reducing...

This study was designed to examine whether n-3 and n-6 polyunsaturated fatty acids (PUFA) at a very low level in the diet (about 0.2%) may alter the fatty acid composition of mitochondrial outer membranes and the characteristics of carnitine palmitoyltransferase I (CPTI) activity in the liver of normal Wistar rats. The animals were fed diets contai...

This study was designed to examine whether the depletion of l-carnitine may induce compensatory mechanisms allowing higher fatty acid oxidative activities in liver, particularly with regard to mitochondrial carnitine palmitoyltransferase I activity and peroxisomal fatty acid oxidation. Wistar rats received d-carnitine for 2 days and 3-(2,2,2-trimet...

The urea cycle takes place in the hepatocyte of ureothelic animals. The conversion of ammonia into urea involves five reactions. The first 2 take place in the matrix of the mitochondria, the last 2 occur in the cytosol. Argininosuccinate synthetase (AS) is the third reaction of the urea cycle. It catalyses the condensation of citrulline and asparta...

Argininosuccinate synthetase (AS) is the third enzyme in ureogenesis, it catalyses the reaction of condensation of citrulline and aspartate into argininosuccinate. In the present report, we described the first characterization of AS within the outer membrane of rat liver mitochondria. Mitochondria-associated AS displayed the same kinetic characteri...

Murine macrophages respond to endotoxins by inducing a vast array of genes that play a major role in the host's response to infection and tumor growth. We have isolated and characterized a 1.8-kb cDNA, designated IRG2, from a cDNA library prepared from RNA isolated from the murine cell line, RAW 264.7, after bacterial LPS stimulation. The cDNA enco...

Citrullinemia is a recessive genetic disease caused by a deficiency in argininosuccinate synthetase (AS). Retroviruses were used to transduce the human AS gene into cultured human cells. Using amphotropic viruses with high titer (> 10(6) cfu/ml), we were able to correct the defect in cultured fibroblasts from citrullinemic patients. Retroviral tran...

Amphotropic and ecotropic packaging cell lines were used to obtain high titers (greater than 10(6) colony forming units/ml) of retroviruses encoding human argininosuccinate synthetase, and these viruses were used to transduce murine bone marrow cells using cocultivation in vitro. The bone marrow cells were transplanted into lethally irradiated reci...

The development and hormonal regulation of thioredoxin and of the thioredoxin-reductase system were investigated during the perinatal period in rat liver. An immunological procedure was developed in order to quantify thioredoxin in fetal and neonatal hepatocytes. Both immunoreactive thioredoxin and thioredoxin-reductase activity appeared on day 16....

Argininosuccinate synthetase (ASS, EC 6.3.4.5), the third enzyme of urea-cycle, was studied in desactivated extracts of rat liver. The enzyme is activated, in vitro, by Mg2+ ions (5 mM) and dithiothreitol (DTT: 10 mM). After reduction by DTT, thioredoxins isolated from rat liver were able to activate ASS by 370%.

The five urea cycle enzymes were studied in desactivated extracts of rat liver. After reduction by dithiothreitol (DTT) and in presence of Mg2+ ions, thioredoxines isolated from rat liver were able to activate carbamyl phosphate synthetase-I (CPS-I) and argininosuccinate synthetase (ASS) respectively by 468% and by 370%. Thioredoxines were purified...