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Biomedical subjects

J Arnaud

Publications and source records attributed to J Arnaud.

At least 19 recordsLinked to original sources
PubMed2001

Plasma fatty acid status in Moroccan children: increased lipid peroxidation and impaired polyunsaturated fatty acid metabolism in protein-calorie malnutrition.

In previous studies on plasma fatty acid and antioxidant status in 29 malnourished Moroccan children (12 with mild protein-calorie malnutrition, 17 with severe protein-calorie malnutrition) compared to 15 healthy control children from the same area, we pointed out that these populations were heterogeneous in terms of their essential fatty acid and antioxidant status. The aim of the present study was to classify the children using the Waterlow classification and their essential fatty acid status. The discrepancies in lipid parameters, nutritional and inflammatory markers, blood oxidative indexes, antioxidant micronutrients or trace elements (selenium, zinc, vitamin E) related to polyunsaturated fatty acids were checked in these populations. Eight of the control subjects and nine of the severe protein-calorie malnutrition children were essential fatty acid-deficient, compared to only one of the mild protein-calorie malnutrition group. Examination of the essential fatty acid-sufficient subjects with mild protein-calorie malnutrition, compared to the essential fatty acid-sufficient control subjects, showed only a decrease in Z scores and a non-significant decrease in selenium and vitamin E. In severely malnourished children, albumin, cholesterol and low density lipoprotein (LDL) cholesterol, plasma selenium, vitamin E and zinc were low, whereas inflammatory proteins and triglycerides were high. These features worsened with essential fatty acid deficiency. In all protein-calorie malnutrition subjects, there was oxidative stress (increase in thiobarbituric-acid reactants, imbalance between plasma polyunsaturated fatty acid, vitamin E and selenium levels), even in the absence of essential fatty acid deficiency. Monounsaturated fatty acids, oleic acid/stearic acid (C18:1 n-9/C18:0) delta9 desaturase and n-3 and n-6 elongase activity indexes increased. The C18:1/C18:0 delta9 desaturase activity index was negatively correlated to Z scores (r = -0.44, P< 0.01 for Z score weight, r = -0.39, P < 0.01 for Z score height), albumin (r = -0.82, P < 0.01) and zinc (r = -0.51, P< 0.01) levels. In essential fatty acid-deficient, severe protein-calorie malnutrition subjects, delta6 desaturase activity was impaired, and there was a non-significant decrease in arachidonic acid. Essential fatty acid deficiency is a type of malnutrition, and is associated with an aggravation of all parameters in severe protein-calorie malnutrition. The increase in the C18:1/C18:0 delta9 desaturase activity and enhanced lipid peroxidation without any essential fatty acid deficiency could be early markers of protein-calorie malnutrition.

Antioxidants↗
PubMed2001

Blood micronutrients in Algeria, relationships with sex and age.

Despite trace elements and vitamins are major public health problems in some African countries, there are few studies reporting micronutrient status in North Africa. Therefore, it could be interesting to evaluate plasma concentrations of vitamin A, E and beta-cartene, along with zinc, copper, selenium erythrocyte glutathione peroxidase and superoxide dismutase in Algeria. Volunteers were randomly recruited in Constantine, Batna and Mila. Vitamins, trace elements and enzymes were measured in the University Hospital of Grenoble. 455 persons were included in the study. Subjects were divided in 3 groups: group I: 15 girls and 12 boys who were 6 to 12.9 years old, group II: 190 women and 192 men 13 to 49.9 years old, group III: 24 women and 24 men 50 to 65 years old. Plasma concentrations of micronutrients and enzymes are close to those commonly observed in Europe, except for vitamin A concentrations. Indeed, retinol levels are 30-35% lower than those reported in European countries, moreover almost 8% of the population showed retinol concentrations less than 1.05 mumol/l. beta-Carotene levels were also lower than in the French average population. Ten per cent of the population had plasma zinc levels lower than 10.6 mumol/l. Vitamin E, copper and selenium status seems satisfactory in Algeria. Vitamin A is not a public health problem, however a significant percentage of residents exhibits impaired vitamin A levels and may benefit from retinol supplementation. Larger studies are needed, and particularly in children, to detect possible higher prevalence of vitamin A deficiency in poor socio-economical classes and in inner geographic areas.

Adolescent↗
PubMed2001

Seasonal variations of antioxidant imbalance in Cuban healthy men.

OBJECTIVE: To determine the antioxidant imbalance in healthy Cuban men 2y after the end of the epidemic neuropathy (50 862 cases from 1991 to 1993) and to evaluate its change over 1 y. DESIGN: Prospective study. SETTING: La Lisa health centres (Havana, Cuba). SUBJECTS: One-hundred and ninety-nine healthy middle-aged men were selected and 106 completed the study. Subjects were studied at 3 month intervals over 1 year. INTERVENTIONS: No invervention. MAIN OUTCOME MEASURES: An assessment of dietary intake and the determination of blood lipid peroxides (TBARS), glutathione, diglutathione, glutathione peroxidase, superoxide dismutase, vitamin E, carotenoids, copper, zinc and selenium were performed at each period. RESULTS: While dietary zinc, vitamins C and E, carotenoids and fat dietary intakes and blood concentrations were low for adult men compared to international reference ranges, serum TBARS concentrations were high at every period. Some significant seasonal variations were observed. The lowest carotenoids (P < 0.002) and vitamin C(P = 0.0001) intakes, serum beta-carotene (P = 0.0001) and lutein/zeaxanthin (P < 0.05) concentrations, and the highest blood TBARS (P = 0.0001) and diglutathione (P < 0.001) concentrations were observed at the end of the rainy season (October). This period seemed to pose the greatest risk of antioxidant imbalance. CONCLUSIONS: Cuban men still represent a vulnerable population in terms of antioxidant imbalance. A national program of vegetable growing and increase in fruit and vegetable consumption is now evaluated in Cuba.

Adult↗
PubMed2001

Molecular modelling and endoplasmic reticulum retention of mutated TCR/CD3 complexes.

T cell receptor (TCR)/CD3 complex assembly takes place in the endoplasmic reticulum (ER). Normal TCR/CD3 complexes egress from the ER to the cis-Golgi, where the interaction with zeta2 homodimers occurs. This interaction leads to further uncontrolled transport of TCR/CD3/zeta molecules to the cell surface. The purpose of the present experiments was to determine firstly the basis for the impact of the Phe195/216 --> Val mutations on TCR/CD3 expression in Jurkat cells, and secondly why mutated J79-cell TCRalphabeta/CD3 hexamers are prevented from interacting with zeta2 homodimers. We found that Phe --> Val mutations cause serious perturbations in a so far undefined hydrophobic area formed by the two Phe195/216 on beta-strand F and aromatic/large hydrophobic amino acids on neighboring beta-strands B and A in Calpha and Cbeta domains, respectively. In addition, TCR/CD3 hexamers and zeta2 homodimers colocalize in normal Jurkat T cells, in revertant J79r58 cells, and in J79 cells transfected with wild-type TCRalpha cDNA but not in J79 mutant cells (confocal microscopy). Furthermore, mutated TCR/CD3 complexes seem to be actively retained in the ER in J79 cells but not in revertant J79r58 cells by a nondominant mechanism. We propose that a hitherto undefined ER-retention molecule controls both the protein structure and egress of TCR/CD3 complexes from the ER of alphabeta and gammadelta T cells.

Brefeldin A↗
PubMed2001

Vitamin B intake and status in healthy Havanan men, 2 years after the Cuban neuropathy epidemic.

A prospective epidemiological study was carried out over 1 year to evaluate vitamin B complex dietary intake and status in Cuba, 2 years after the Cuban neuropathy epidemic of 1993. Of the 199 healthy middle-aged men selected, 141 completed the study. Volunteers were followed up every 3 months for 1 year. Dietary intake and status of thiamin, riboflavin, vitamin B6, folate and vitamin B12 were assessed each time. The dietary intake of vitamin B complex was low, particularly in June and July (folate), and October (thiamin). A deficient status was observed for vitamin B complex, except for vitamin B6. Vitamin B complex intake and status varied over the year. However, dietary intake and status were poorly related. The results prove that healthy Cuban men represent a vulnerable population in terms of vitamin B complex status and stress the necessity to both promote preventive multivitamin supplementation and produce local food rich in vitamin B complex.

Adult↗
PubMed2001

Selenium status in an iodine deficient population of the West Ivory Coast.

Selenium is an essential trace element which is part of the active site of seleno-dependent glutathione peroxidase and type 1 deiodinase. Therefore, it plays a key role in thyroid hormone metabolism. The present work was undertaken in order to evaluate selenium status in two Ivory Coast populations: the first with high (Glanlé) and the second with low (Abidjan) prevalence of iodine deficiency. Selenium, glutathione peroxidase, glutathione reductase, glutathione and diglutathione were determined in blood and/or urine. In plasma and erythrocytes, selenium and glutathione peroxidase were dramatically low in Glanlé. Compared to Abidjan, selenium, glutathione peroxidase, vitamin E and riboflavin status were decreased whereas diglutathione was increased in Glanlé. The results clearly demonstrate a selenium deficiency and suggest an oxidant stress in Glanlé. Causes and consequences of this selenium deficiency and oxidant stress remain to be determined.

Anthropology, Cultural↗
PubMed2000

[Iron metabolism].

Iron is essential to the human organism but is also highly toxic. Therefore, in the organism, iron is always tightly bound to specific proteins. In the past few years, our understanding of iron cellular uptake and regulation mechanisms has been expanded. However, iron metabolism, particularly its intestinal absorption and release from ferritin, is still uncompletely understood. Intestinal absorption appears to be the prime factor of iron homeostasis control. Iron deficiency is one of the most common nutritional problems in the world. However, oxidative stress induced by iron overload has been implicated in a growing number of diseases.

Cells↗
PubMed2000

On the genetic mechanism of induction of CD3gamma-negative human T cell variants.

Invariant CD3gamma molecules are important components in TCR complex formation and function. Both CD3gamma alleles seem to be expressed co-dominantly. In the present report, we present experimental data which indicate that the induction of CD3gamma(-) Jurkat variants occurs with a frequency similar to that of TCRalpha(-) or TCRbeta(-) Jurkat cells. CD3delta(-), CD3epsilon(-) or CD3zeta(-) Jurkat variants were never obtained despite extensive efforts. Our data suggest a possible explanation for this genetic puzzle: the human CD3gamma gene has a mutational hot spot in a nucleotide sequence of nine adenosines (9A) in the exon 3 encoding most of the external CD3gamma domain. Thus, both CD3gamma alleles are easily mutated to either 8A or 10A sequences. Furthermore, absence of CD3gamma molecules in Jurkat T cells causes severe defects in TCR / CD3 assembly and function.

Cell Differentiation↗
PubMed2000

Vitamin and nutritional status in Cuban smokers and nonsmokers in the context of an emerging epidemic neuropathy.

A prospective survey was conducted in a random sample of smokers (SMO) and non-smokers (NON) men living in Havana. The aim of the survey was to investigate metabolic and dietary parameters discriminating between SMO and NON volunteers, which could explain underlying mechanisms to the higher risk of Epidemic Neuropathy (51,000 reported cases in Cuba from late 1991) previously demonstrated in the Cuban smoker. Forty three blood markers were determined and dietary intakes evaluated during 4 seasonal periods. alpha-carotene, beta-carotene, beta-cryptoxanthin, total carotenoids and riboflavin blood concentrations were lower in SMO vs. NON subjects. Activities of glutathione reductase and butryrylcholinesterase were lower in the SMO group, as did total protein levels. Copper and thiocyanates were higher in SMO subjects. Most of the dietary parameters did not differ between the two groups of volunteers. Low biologically available quantities of carotenoids and riboflavin from low dietary intakes and depletion through smoking would be the main precipitating factors of Epidemic Neuropathy. Protein depletion and copper delivery via tobacco smoke, sunlight exposure, level of physical activity and high consumption of cigarettes, in a context of low dietary supplies concerning especially B vitamins, were probably aggravating factors through oxidative stress and impairment of cyanide detoxification.

Adult↗
PubMed2000

Dissection of the role of CD3gamma chains in profound but reversible T-cell receptor down-regulation.

T-lymphocyte activity in the immune system is regulated by the quantity of surface membrane T-cell antigen receptors (TCR). The amount of surface-bound TCR is dependent on the rate of [1] biosynthesis, assembly and intracellular transport of the individual chains composing the TCR/CD3 complex and [2] the internalization and recycling of the receptors. The TCR-ligand interaction augments receptor internalization. In the present paper, we have studied short- and long-term down-regulation of TCR/CD3 complexes with monoclonal anti-TCR/CD3 antibodies, and attempted to determine which component(s) of the TCR/CD3 complex are responsible for these two phenomena. Our data indicate that short- and long-term down-regulation is mediated by different mechanisms, and that the extracellular and/or transmembrane regions of CD3gamma molecules appear to play an important role in chronic TCR/CD3 down-regulation and subsequent deficient re-expression. These results may have important implications for the understanding of induction of T-cell tolerance or anergy.

Antibodies, Monoclonal↗
PubMed2000

Cognitive decline is associated with systemic oxidative stress: the EVA study. Etude du Vieillissement Artériel.

OBJECTIVE: To determine whether systemic oxidative stress status is associated with cognitive decline. DESIGN: A longitudinal population-based study. SETTING: A cohort study of older subjects in Nantes, France. PARTICIPANTS: A total of 1166 high cognitive functioning subjects aged 60 to 70 in the Etude du Vieillissement Arteriel (EVA) cohort with a 4 year follow-up. MEASUREMENTS: Subjects completed a baseline interview and a global cognitive test (Mini-Mental Status Examination (MMSE)). Blood samples were obtained at baseline to determine plasma levels of selenium, carotenoids, thiobarbituric acid reactant substances (TBARS), an indicator of lipoperoxidation, and red blood cell vitamin E. Risk of cognitive decline, defined as a loss of 3 points in MMSE score between baseline and the 4 year follow-up, was assessed by oxidative stress level. RESULTS: Subjects with the highest levels of TBARS show an increased risk of cognitive decline (adjusted odds ratio (OR) = 2.25; confidence interval (CI) 95% = 1.26-4.02). This result is reinforced in the lower antioxidant status subgroup. Subjects with low levels of selenium have an increased risk of cognitive decline (OR = 1.58; CI 95% = 1.08-2.31) after adjustment for various confounding factors. CONCLUSIONS: These results suggest that increased levels of oxidative stress and/or antioxidant deficiencies may pose risk factors for cognitive decline. The direct implication of oxidative stress in vascular and neurodegenerative mechanisms that lead to cognitive impairment should be further explored.

Aged↗
PubMed1999

Impact of trace elements and vitamin supplementation on immunity and infections in institutionalized elderly patients: a randomized controlled trial. MIN. VIT. AOX. geriatric network.

BACKGROUND: Antioxidant supplementation is thought to improve immunity and thereby reduce infectious morbidity. However, few large trials in elderly people have been conducted that include end points for clinical variables. OBJECTIVE: To determine the effects of long-term daily supplementation with trace elements (zinc sulfate and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) on immunity and the incidence of infections in institutionalized elderly people. METHODS: This randomized, double-blind, placebo-controlled intervention study included 725 institutionalized elderly patients (>65 years) from 25 geriatric centers in France. Patients received an oral daily supplement of nutritional doses of trace elements (zinc and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) or a placebo within a 2 x 2 factorial design for 2 years. MAIN OUTCOME MEASURES: Delayed-type hypersensitivity skin response, humoral response to influenza vaccine, and infectious morbidity and mortality. RESULTS: Correction of specific nutrient deficiencies was observed after 6 months of supplementation and was maintained for the first year, during which there was no effect of any treatment on delayed-type hypersensitivity skin response. Antibody titers after influenza vaccine were higher in groups that received trace elements alone or associated with vitamins, whereas the vitamin group had significantly lower antibody titers (P<.05). The number of patients without respiratory tract infections during the study was higher in groups that received trace elements (P = .06). Supplementation with neither trace elements nor vitamins significantly reduced the incidence of urogenital infections. Survival analysis for the 2 years did not show any differences between the 4 groups. CONCLUSIONS: Low-dose supplementation of zinc and selenium provides significant improvement in elderly patients by increasing the humoral response after vaccination and could have considerable public health importance by reducing morbidity from respiratory tract infections.

Aged↗
PubMed1999

Are copper, zinc and selenium in erythrocytes valuable biological indexes of nutrition and pathology?

The real significance of the level of trace elements copper, zinc and selenium in erythrocytes is still a matter of debate. This review is an evaluation of the potential value of copper, zinc and selenium in red blood cells in physiology, nutrition and pathology, taking into account the other commonly used indices and the analytical difficulty encountered for erythrocyte determinations. The main analytical methods and reference values in erythrocytes are also presented. The literature of the last 3 decades was analyzed. On the basis of these papers, the role of erythrocyte copper in various pathologies should be re-investigated, especially when they include inflammatory processes or hormonal changes. The main interest of zinc determination in red blood cells concerns thyroid pathology. In general, the value of selenium in erythrocytes agrees with selenium in serum and its determination is often unnecessary.

Copper↗
PubMed1999

Microspatial genetic structure in the land snail helix aspersa (Gastropoda: helicidae)

The microspatial genetic structure of allele frequencies at seven isozyme loci was examined for 15 populations of the land snail Helix aspersa sampled in a village from Brittany (north-western France). Spatial heterogeneity of allele frequencies was highly significant (P < 0.001). Fixation indices reflected nonrandom mating within neighbourhoods and a slight but consistent differentiation between colonies (FST=0.044; P < 0.01). Analyses of gene flow or genetic distances failed to reveal a significant relationship with geographical distance, probably because of the complexity of environmental heterogeneity. However, matrix comparisons between genetic distances and connectivity networks among adjacent colonies (Gabriel-connected graph) yielded a significant correlation in every case, indicating a 'step-by-step' relationship between neighbouring localities. Moreover, most of the allozymes were spatially structured and showed (i) a gradual isolation of colonies with increasing geographical distances, and (ii), for some correlogram profiles, a circular gradient illustrating a multidirectional colonization of the village. The probable existence of disperser individuals allowed us to suggest a metapopulation model which would explain the maintenance of such animals in fragmented habitats where anthropogenic disturbances and extinction/recolonization events are commonly observed.

Journal Article↗
PubMed1999

Molecular mechanisms in the TCR (TCR alpha beta-CD3 delta epsilon, gamma epsilon) interaction with zeta 2 homodimers: clues from a 'phenotypic revertant' clone.

The association between the TCRalphabeta-CD3gammaepsilondeltaepsilon hexamers and zeta2 homodimers in the endoplasmic reticulum (ER) constitutes a key step in TCR assembly and export to the T cell surface. Incompletely assembled TCR-CD3 complexes are degraded in the ER or the lysosomes. A previously described Jurkat variant (J79) has a mutation at position 195 on the TCR Calpha domain causing a phenylalanine to valine exchange. This results in a lack of association between TCRalphabeta-CD3gammaepsilondeltaepsilon hexamers and zeta2 homodimers. Two main hypotheses could explain this phenomenon in J79 cells: TCR-CD3 hexamers may be incapable of interacting with zeta2 due to a structural change in the TCR Calpha region; alternatively, TCR-CD3 hexamers may be incapable of interacting with zeta2 due to factors unrelated to either molecular complex. In order to assess these two possibilities, the TCR-CD3 membrane-negative J79 cells were treated with ethylmethylsulfonate and clones positive for TCR membrane expression were isolated. The characterization of the J79r58 phenotypic revertant cell line is the subject of this study. The main question was to assess the reason for the TCR re-expression. The TCR on J79r58 cells appears qualitatively and functionally equivalent to wild-type TCR complexes. Nucleotide sequence analysis confirmed the presence of the original mutation in the TCR Calpha region but failed to detect compensatory mutations in alpha, beta, gamma, delta, epsilon or zeta chains. Thus, mutated J79-TCR-CD3 complexes can interact with zeta2 homodimers. Possible mechanisms for the unsuccessful TCR-CD3 interaction with zeta2 homodimers are presented and discussed.

Cell Membrane↗
PubMed1998

Effects of supplementation with a combination of antioxidant vitamins and trace elements, at nutritional doses, on biochemical indicators and markers of the antioxidant system in adult subjects.

OBJECTIVE: To test the impact of supplementation with nutritional doses of antioxidant nutrients on biochemical indicators of vitamin and trace element levels. DESIGN: A randomized double-blind trial was performed comparing two groups receiving daily either a combination of vitamins (beta-carotene, 6 mg; vitamin C, 120 mg; and vitamin E, 30 mg) and trace elements (zinc, 20 mg; and selenium, 100 micrograms); or a placebo. SUBJECTS: 401 subjects (166 males aged 45 to 60 years and 235 females aged to 35 to 60 years). MEASURE OF OUTCOME: Biological markers of vitamin and trace element status and free radical parameters were measured initially, 3 months, and 6 months after supplemention. RESULTS: Mean serum concentrations of alpha-tocopherol, vitamin C, beta-carotene, zinc and selenium increased significantly after 3 months of supplementation in the group receiving multivitamins associated with minerals. At baseline, 18.2% of the men and 5.1% of the women had low concentrations of serum vitamin C (< 20 mumol/l): 2.4% of the men and 17% of the women presented low concentrations of serum retinol (< 1.4 mumol/l): 18.7% of men and 10% of women had serum beta-carotene < 0.30 mumol/l. None of the study subjects had serum alpha-tocopherol concentrations below the limit cut-off point (< 9.3 mumol/l). Low serum zinc concentrations (< 10.7 mumol/l) were found in 15.1% of men and 23.8% of women. Low serum selenium concentrations (< 0.75 mumol/l) were found in 6% of men and 6.4% of women. A significant increase in plasma and red cell GPx activity was observed in groups receiving supplementation. No modifications were observed after 6 months of supplementation for malondyaldehyde. CONCLUSION: This study demonstrates the efficacy of an intake of antioxidant vitamins and trace elements, given at nutritional doses, on biochemical indicators of vitamin and trace elements status.

Adult↗
PubMed1998

Background and rationale behind the SU.VI.MAX Study, a prevention trial using nutritional doses of a combination of antioxidant vitamins and minerals to reduce cardiovascular diseases and cancers. SUpplementation en VItamines et Minéraux AntioXydants Study.

The "SUpplementation en VItamines et MinérauxAntioXydants" (SU.VI.MAX) study is a randomized double-blind, placebo-controlled, primary prevention trial designed to test the efficacy of daily supplementation with antioxidant vitamins (vitamin C, 120 mg; vitamin E, 30 mg; and beta-carotene, 6 mg) and minerals (selenium, 100 micrograms; and zinc, 20 mg), at nutritional doses (one to three times the daily recommended dietary allowances), in reducing the frequency of major health problems in industrialized countries, and especially the main causes of premature death (cancers and cardiovascular diseases). The study involves 12,735 eligible subjects (women aged 35 to 60 years; men aged 45 to 60 years) included in 1994 in France. They will be followed up for 8 years. The objectives and the specific design of this intervention study are linked to its public health aim. The targeted population is the general population (not simply high-risk subjects) and the antioxidant agents tested are being administered at a level which is not pharmacologic and which may be attained by dietary intake of natural sources of these micronutrients and/or enriched foods. The amounts we are testing in the SU.VI.MAX study are those which, in observational studies have been associated with the lowest risk of diseases. This report presents the rationale and discusses the justification of the design, doses and combination of antioxidant micronutrients chosen in the SU.VI.MAX study.

Adult↗