Stress oxydant, fonctions vasculaires et athéroscléroseOxidative stress, vascular function and atherosclerosis

The vascular endothelium plays a major role in the regulation of the vascular tone, in response to several stimuli such as prostacyclin, endothelin and above all nitric oxide (NO^•). Oxidative stress, which is characterized by a relative increased level of reactive oxygen species (ROS), is able to decrease NO^• biodisponibility. This leads to a vascular dysfunction. In addition, ROS (produced in part by NADPH oxidase) participate, either directly or via oxidized low density lipoproteins, to signal transduction in vascular cells. They are thus involved in apoptosis, smooth muscle cell proliferation, monocyte adhesion to endothelial cells or platelet aggregation. Therapeutics which could modulate ROS production in the endothelial cells could be proposed to restore endothelial function.     

Stress oxydant et vieillissement

In aging, an increased production of mitochondrial oxygen reactive species, associated with decreased anti-oxidant defences results in an unbalanced pro/anti-oxidant equilibrium. This increased oxidative stress leads to an higher incidence of oxidative pathologies such as cardiovascular diseases, cancers or neurodegenerative diseases. Elderly people exhibit high levels of biological oxidative stress indices and a lowered anti-oxidant status. Deficiencies are worsened by institutionalisation, hospitalisation and pathologies. Supplementation trials, using combined anti-oxidants, vitamins, and trace-elements intakes, are beneficial especially in restoring immune functions. These interventional supplementations have to be considered as soon as a pathological event happens.     

Stress oxydant et vieillissementOxidative stress, nutrition and aging

In aging, an increased production of mitochondrial oxygen reactive species, associated with decreased anti-oxidant defences results in an unbalanced pro/anti-oxidant equilibrium. This increased oxidative stress leads to an higher incidence of oxidative pathologies such as cardiovascular diseases, cancers or neurodegenerative diseases. Elderly people exhibit high levels of biological oxidative stress indices and a lowered anti-oxidant status. Deficiencies are worsened by institutionalisation, hospitalisation and pathologies. Supplementation trials, using combined anti-oxidants, vitamins, and trace-elements intakes, are beneficial especially in restoring immune functions. These interventional supplementations have to be considered as soon as a pathological event happens.     

Éléments traces, stress oxydant et hépatopathies alcooliques

Marked disorders in trace-element homeostasis occurred following various experimental conditions of ethanol administration. A decrease in zinc, copper and selenium, and an increase in non-heme iron are often observed at the hepatic level. Some of these alterations may contribute to collagen accumulation and to the decrease in the major enzymatic antioxidants such as superoxide dismutase (Cu, Zn-SOD) and glutathion peroxidase (Se-GPx). The decrease in the antioxidant defense associated with the increase in the low molecular weight non-heme iron complexes or redox active iron, a pro-oxidant factor, may play a prominent role in the occurrence of oxidative stress, which leads to enhanced lipid peroxidation. The severity of inflammatory and fibrotic disorders, which has been reproduced in rats by long-term ethanol administration associated with a high fat diet, is correlated to the intensity of oxidative stress. Clinical studies report alterations in trace elements and in some parameters of oxidative stress in patients suffering from alcohol-dependent liver disease. Supplementation with selenium and/or zinc may be considered in the prevention of the progressive alcoholic liver injury.     

Oxidative stress modulation in neurodegenerative diseases

The primary pathological feature of neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and amyotrophic lateral sclerosis is the slow and progressive selective dysfunction and loss of neurons and axons in the central nervous system. Despite different triggering events, a common feature is the involvement of oxidative stress. Several evidences indicate that oxidative stress is critical for neurodegeneration. Here, we review the impact of oxidative stress involvement in neurodegenerative disorders, and discuss its contribution to neurons damage. We also discuss potential antioxidant therapies to modulate oxidative stress in this group of diseases. A better understanding of the imbalance between the production of reactive oxygen species and the ability of nervous system to remove them or repair the ensuing damage will be crucial for the development of new potential therapeutic strategies.     

Oxygène, stress oxydant et supplémentations antioxydantes ou un aspect différent de la nutrition dans les maladies respiratoires

Dioxygen is an element essential to our survival, our life, our development, our capacity of adaptation. Nevertheless, dioxygen is also at the origin of toxicity, acidity, deterioration, degeneration. Indeed, when the metabolism of dioxygen is altered, as in the respiratory diseases, an “oxidative stress” can appeared and induced metabolic anomalies associated with important consequences. Oxidative stress is defined as an imbalance between pro-oxidant (reactive oxygen species) and antioxidant factors, in favour of the former. The genomic, metabolic and functional modifications induced by oxidative stress were implied in the development of various degenerative diseases. Antioxidant treatments, in a nutritional or pharmacological way, appeared consequently as new potent therapies. In this review, the role of dioxygen in the cellular metabolism, and in the production of the reactive oxygen species is discussed. The negative effects of the oxidative stress on the organism are reported. Finally, the results of the studies on the nutritional antioxidant treatment firstly in the degenerative diseases, secondly in a chronic respiratory disease, the chronic obstructive pulmonary disease, are discussed in a last part.     

État nutritionnel des patients avec maladies du foie : épidémiologie et pronostic

Malnutrition is generally defined as protein-energy malnutrition (PEM) in patients with chronic liver disease, because the depletion of muscle mass and body fat is associated with protein depletion. Deficiencies of vitamins and minerals often coexist. PEM represents a common complication of advanced liver disease, both of alcoholic and nonalcoholic etiology. It is related to the severity of the liver disease more than to its etiology.Malnutrition negatively affects liver function, complications of the liver disease, and survival. Malnourished patients have an increased surgical risk and decreased survival after liver transplantation. The assessment of nutritional status in patients with chronic liver disease may be helpful in providing better prognostic information and more precise targeting of potential nutrition intervention.     

Stress oxydant au cours des syndromes inflammatoires chroniquesOxidative stress in chronic inflammatory syndromes

Oxidative stress, characterised by an increase in reactive oxygen mediators and/or a decrease in micronutrient availability leading to dysfunction of anti-oxidant defences, constitutes one of the factors contributing to the onset and/or perpetuation of chronic inflammatory syndromes. There is increasing evidence that oxidative stress is a major player in inflammatory bowel disease, chronic respiratory diseases like cystic fibrosis and asthma, or rheumatoid arthritis, and may be a potential therapeutic target. The objective of this review is to summarise present knowledge on the pathophysiological role of oxidative stress in the above mentioned diseases and to emphasize the current role of pharmacological and nutritional interventions designed to restore an appropriate oxidant/anti-oxidant balance.     

Stress oxydant au cours des états inflammatoires aigus et des états d’agression : implications pour la pratique cliniqueOxidative stress during acute inflammatory and critical states: implications for clinical practice

Oxygen free radicals (OFR) production and consumption are balanced in health. In acute inflammatory disease, OFR may overwhelm host defence mechanisms, a condition known as oxidative stress. They have been implicated in the pathogenesis of a wide variety of diseases. Oxidative stress plays a pivotal role in inflammatory situations and critical illness such as Systemic Inflammatory Response Syndrome, septic shock, adult respiratory distress syndrome, burns, trauma, and renal failure. Deficiencies in anti-oxidant defences include depletion of glutathione, vitamins A, C and E and selenium. Preventing the initiation or controlling the progression of local or systemic disease processes that complicate the course of critically ill patients with anti-oxidant therapies is an actual strategy. This review will present trials with single or multiple anti-oxidant therapies in critical situations. These studies strongly suggest that patients should benefit from anti-oxidant therapy. To date, data to support routine use of anti-oxidants in critical illness are limited. The choice of anti-oxidants dosage and appropriate target populations must be better defined.     

Place et impact des régimes chez les personnes très âgées

Successful ageing promotion is a major goal of care in geriatrician patients, even in old age. Cardiovascular prevention strategy, diabetes care or kidney protection involve dietary management. However, mortality and morbidity risk factors are modified in the oldest old, and on the other hand, dietary restrictions could impair health status of the older. Studies devoted to the oldest old are scarce. In most situations, exercise training promotion seems to better address the prevention goals than do diets.     

Allaitement maternel et lait maternel : quels bénéfices pour la santé de l’enfant

Breastfeeding has been shown to be beneficial for the health of neonates infants, mainly for the prevention of infectious diseases. Other beneficial effects such as prevention of atopic diseases or prevention of obesity has been also suggested. The optimal breastfeeding duration is still a matter of debate. Most of the beneficial effects were reported systematically for a duration of three months or more. However, there is a dose-dependent effect and breastfeeding, even for a short duration is beneficial for infants. Exclusive breastfeeding is presently recommended for six months, with introduction of complementary feeding at that time.     

Role of oxidative stress and antioxidants in neurodegenerative diseases

Neurodegenerative diseases (NDD) are a group of illness with diverse clinical importance and etiologies. NDD include motor neuron disease such as amyotrophic lateral sclerosis (ALS), cerebellar disorders, Parkinson's disease (PD), Huntington's disease (HD), cortical destructive Alzheimer's disease (AD) and Schizophrenia. Numerous epidemiological and experimental studies provide many risk factors such as advanced age, genetic defects, abnormalities of antioxidant enzymes, excitotoxicity, cytoskeletal abnormalities, autoimmunity, mineral deficiencies, oxidative stress, metabolic toxicity, hypertension and other vascular disorders. Growing body of evidence implicates free radical toxicity, radical induced mutations and oxidative enzyme impairment and mitochondrial dysfunction due to congenital genetic defects in clinical manifestations of NDD. Accumulation of oxidative damage in neurons either primarily or secondarily may account for the increased incidence of NDD such as AD, ALS and stroke in aged populations. The molecular mechanisms of neuronal degeneration remain largely unknown and effective therapies are not currently available. Recent interest has focused on antioxidants such as carotenoids and in particular lycopene, a potent antioxidant in tomatoes and tomato products, flavonoids and vitamins as potentially useful agents in the management of human NDD. The pathobiology of neurodegenerative disorders with emphasis on genetic origin and its correlation with oxidative stress of neurodegenerative disorders will be reviewed and the reasons as to why brain constitutes a vulnerable site of oxidative damage will be discussed. The article will also discuss the potential free radical scavenger, mechanism of antioxidant action of lycopene and the need for the use of antioxidants in the prevention of NDD.     

L'altération des fonctions sensorielles et de l'appétit est-elle une fatalité chez le sujet âgé ?

Profound differences of appetite occur in older persons. Appetite correlates poorly with body weight in older persons, leading to failure to increase ingestion of nutrients in response to weight loss. Older persons exhibit less hunger and earlier satiety. Dramatic and poorly understood alterations occur in the physiologic regulation of appetite. The response to social and psychological stimulants is similar to younger adults. The screening for sensory impairment should be included in the comprehensive geriatric assessment. Pharmacologic stimulants of appetite suggest a promising intervention for anorexia.     

Variation de l'équilibre hydrique de la personne âgée

Total body water is the sum of extracellular and intracellular compartments, and is reduced with age. This, together with the difficulties to maintain and fine tune water inflows and outflows make the elderly person highly succeptible to dehydration during acute episodes of disease. Clinical and biogical evaluation are indirect and the only validated tools to estimate hydration status. Measurements of body water spaces by isotope dilution or bioelectrical impedance analysis are possible and technically reliable. However, measured values need to be compared with reference values, which are not yet available. Building reference data base is the necessary fisrt step before progress can be made about optimal hydration and its influence over aging.