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Biomedical subjects

J Nève

Publications and source records attributed to J Nève.

At least 19 recordsLinked to original sources
PubMed1991

Interest of zinc determination in leucocyte fractions for the assessment of marginal zinc status.

In order to test the sensitivity of leucocyte zinc determination in the assessment of zinc status, an isolation procedure of mononuclear (MNC) and polymorphonuclear (PMNC) cell fractions was developed. Zinc concentrations in cells from healthy subjects were (mean +/- SD, in mumol/10(10) cells): 0.81 +/- 0.24 in MNC and 0.55 +/- 0.06 in PMNC. In patients suffering from several diseases known to be associated with a marginal impairment in zinc status (cirrhosis, cancer, obesity, endocrine and rheumatic diseases), these concentrations did not differ from those in controls except in rheumatic patients in whom MNC zinc was increased (1.05 +/- 0.42 mumol/10(10) cells) and correlated with erythrocyte sedimentation rate (r = 0.41, P less than 0.01). This relation was also significant in the whole study population (r = 0.39, P less than 0.01). Leucocyte zinc therefore appears to have a limited value in the assessment of marginally impaired zinc status, except in inflammatory states.

Adult↗
PubMed1991

Physiological and nutritional importance of selenium.

The essential trace element selenium has recently attracted attention because of its potentialities in the maintenance of human health. Selenium forms part of the active site of the peroxide-destroying enzyme glutathione peroxidase, and it also has other functions, for example in biotransformation, detoxification and the immune response. Functional and clinical consequences of selenium deficiency states have been described, and the selenium requirement, which is influenced by the usual selenium exposure, has been discussed. Wide variations have been found in selenium status in different parts of the world, and populations or groups of patients exposed to marginal deficiency are more numerous than was previously thought. Current research activities in the field of human medicine and nutrition are devoted to the possibilities of using selenium for the prevention or treatment of degenerative or free radical diseases such as neurological disorders, inflammatory diseases or cancer. Pharmacological selenium doses are also recommended as an adjuvant in some treatments.

Cardiovascular Diseases↗
PubMed1991

Effects of acute and chronic prednisolone treatment on serum zinc levels in rats with adjuvant arthritis.

Several studies in animals and humans have independently demonstrated that zinc metabolism is significantly affected either by inflammation or by glucocorticoid administration. The relative importance of these two factors was assessed in this study by the investigation of the effects on serum zinc concentrations of acute and chronic prednisolone treatments in adjuvant arthritis rats and in healthy controls animals. Acute steroid administration (3 mg/kg, i.p.) caused a rapid drop in serum zinc followed by a quick recovery, regardless to the fact that these concentrations were normal (healthy animals) or already reduced by the inflammatory process. However, the modification occurred faster in inflamed animals. Chronic steroid administration (0.58 to 0.78 mg/kg/day during 1 to 4 weeks) had a more complex effect. A previous experiment in healthy rats demonstrated that such a treatment only induced a slight decrease in serum zinc. In adjuvant arthritis animals, the early steroid treatment of the induced process promoted a further decrease in serum zinc level while a delayed treatment did not result in additional changes.

Animals↗
PubMed1991

Lymphocyte response is enhanced by supplementation of elderly subjects with selenium-enriched yeast.

The effect of selenium supplementation on plasma selenium concentrations and lymphocyte-proliferation responses to mitogens was investigated in 22 elderly institutionalized subjects. Subjects were assigned to a 6-mo trial with either 100 micrograms Se/d (as selenium-enriched yeast) or a placebo. Plasma selenium concentrations of the selenium-supplemented group increased from 0.84 +/- 0.26 to 1.55 +/- 0.33 mumol/L (mean +/- SD) after 2 mo and the values plateaued thereafter. The mean response of lymphocytes to mitogens in elderly subjects tended to be lower than responses in healthy adults, although responses remained within the 5-95% confidence-interval limit for healthy adults. During selenium supplementation the proliferative response to pokeweed mitogen increased significantly (+79% of baseline concentrations after 4 mo, P less than 0.01) and reached the upper limit of the usual range for adults after 6 mo (+138%, P less than 0.001). In accordance with previous studies in animals and in vitro, this investigation demonstrates for the first time immunostimulatory properties of selenium-enriched yeast in elderly humans.

Aged↗
PubMed1991

Methods in determination of selenium states.

Selenium status in man has been assessed either by determination of the selenium concentration in biological materials or by the measurement of biochemical or clinical selenium-dependent functions. Over and above the discussion of normal levels and of the numerous factors liable to influence the above mentioned indices, the present review more specifically deals with the sensitivity of various parameters to changing selenium status, both in deficiency states and in over-exposure to the element, and the attempt is made to establish the specificity of these indicators in the diagnosis of selenium states. The possibilities for defining "adequate" or "optimum" selenium concentrations are also examined.

Erythrocytes↗
PubMed1991

Factors affecting determinations of manganese in serum by atomic absorption spectrometry.

A method was developed for the routine determination of manganese in serum from healthy human subjects by graphite furnace atomic absorption spectrometry. We controlled the experimental conditions rigorously, from sampling to analysis, to minimize contamination and to conserve diluted samples. We optimized the procedure with two serum Reference Materials, one of which had a manganese concentration very close to what is thought to be the physiological concentration in humans. The best analytical performance was obtained by directly injecting into the furnace serum diluted with an equal volume of a solution containing Triton X-100 and sodium EDTA and calibrating by the standard additions procedure or by a calibration graph constructed in a similar matrix. The Zeeman background correction produced better accuracy and precision than did the classical deuterium correction. Within-run CV for a manganese concentration of 12.7 nmol/L in serum was 7.9%, and between-run precision was 16.1%. The mean (SD) serum manganese concentration in 31 healthy adults was 10.8 (SD 3.0) nmol/L. Sex and age of subjects did not affect concentrations.

Blood Specimen Collection↗
PubMed1989

[Selenium: current epidemiological and physiopathological findings. Status in Belgium].

Selenium is an essential trace element involved in the "protection" of organism by its constitution of the active site of the enzyme glutathion peroxydase and its participation in functions such as biotransformation, detoxification and immune response. Functional and clinical consequences of selenium deficiency have been largely described as well as requirements that depend on several "aggression" factors. Further studies are however necessary to demonstrate its activity in the prevention of some chronic diseases.

Antibody Formation↗
PubMed1988

Changes in zinc, copper and selenium status during adjuvant-induced arthritis in rats.

Trace elements such as zinc, copper and selenium are involved in the pathogenesis of inflammatory diseases. In order to obtain more information about the overall movements of these minerals during the evolution of an experimental chronic inflammatory process, trace element levels were determined in five body compartments of the rat at several time intervals after induction of adjuvant arthritis. Rapid and significant changes in plasma zinc and copper levels and in liver zinc levels were observed. These modifications occurred as early as those in biochemical parameters of inflammation such as serum fibrinogen and ceruloplasmin, and preceded the appearance of any clinical symptom of the disease. Inverse correlations were found between plasma zinc levels and these two biochemical indices. Other modifications in trace element levels were observed two weeks after disease induction, the most important being a considerable increase in liver copper levels. Although food intake of affected animals decreased with the progression of the disease, there was no evidence of depletion in zinc and copper levels over the study period. A redistribution of body zinc between different biological compartments (mainly plasma and liver) occurred simultaneously with an accumulation of copper in several organs. The decreasing selenium status of animals was not clearly related to the inflammatory process.

Animals↗
PubMed1988

Selenium supplementation in healthy Belgian adults: response in platelet glutathione peroxidase activity and other blood indices.

Selenium status was explored by investigating effects of a 60-d Se supplementation with DL-selenomethionine (100 micrograms Se/d) in a group of 10 adults (plasma Se levels, 0.76-1.33 mumol/L). Plasma, erythrocyte, and urinary Se and activities of glutathione peroxidase (GSH Px) in plasma, erythrocytes, and platelets were measured before intervention and after 5, 15, 30, 45, and 60 d. A placebo was given to six adults. Plasma and urinary Se were the most sensitive indices to Se exposure. Se in plasma increased steadily during the course of the study whereas urinary Se reached a plateau between 30 and 60 d. By contrast erythrocyte Se did only change after 45 d. Enzyme in plasma and erythrocytes did not respond whereas platelet GSH Px did. The plateau of activity that was observed after 15 d for plasma Se in the range 1.40-1.50 mumol/L could mean that the Se status is insufficient for an optimal function of GSH Px and implies that dietary intake in Belgium (less than 50-60 micrograms Se/d) is not adequate.

Adult↗
PubMed1985

Selenium deficiency.

Selenium is undoubtedly an essential trace element: its involvement in GPx structure, the presence of deleterious effects of selenium deficiency in animals, and the recognition of deficiency states in man attest to its importance. However, if the consequences of selenium deficiency in man are now widely recognized, the mechanisms underlying these conditions are poorly understood. The definition of the exact role of selenium in human homeostasis has been hampered by the lack of a sensitive parameter, usable in routine investigation, to assess selenium status. Measurements of plasma and urinary levels, although useful in clinical practice, are inadequate indicators. The only true evidence of selenium deficiency lies in a positive response to selenium therapy. Deficiency states have been demonstrated for inhabitants of regions where selenium supply is limited, in protein-energy malnutrition, and in patients maintained on total parenteral nutrition without selenium supplementation. The benefit of selenium supplementation, together with other antioxidant drugs, in non-deficient subjects is still a matter of debate; its protective effect in neoplastic, cardiovascular and neurological degenerative diseases is not yet proven.

Animals↗
PubMedDate not supplied

Absorption and metabolism of oral zinc gluconate in humans in fasting state, during, and after a meal.

The absorption and metabolism of zinc in a commercial form for oral use (Rubozinc, 15 mg zinc as gluconate) were investigated in 10 subjects by a kinetic study of the serum zinc profile after administration of 45 mg zinc under three conditions: after an overnight fast, during a standardized breakfast, and 2 h after this meal. The pharmacokinetic parameters were calculated by a method suitable to the characterization of rebound effects (recycling of the element in the gastrointestinal tract). In fasting state, the parameters were comparable to those previously collected in the same subjects with oral 45 mg zinc as sulfate, except with very significantly higher Cmax and area under curve (AUC), showing a better bioavailability for zinc in the commercial form. The light meal perturbed the absorption process as evidenced by the significant increases in the lag time (+180%), the tmax (+57%), and the lag times for the first two cycles during the meal. However, the parameters returned to normal values 2 h after the meal. The Cmax only moderately decreased during the meal (31%) as did the AUC (-28%). An important delay in the absorption of zinc in the commercial form when taken during a meal was therefore demonstrated, but the effect on zinc bioavailability was only moderate.

Administration, Oral↗
PubMedDate not supplied

Pharmacokinetic study of orally administered zinc in humans: evidence for an enteral recirculation.

Starting from the experimental design of the established 'Zinc Tolerance Tests', the absorption and distribution of the essential trace element zinc in humans was investigated in 10 subjects by performing a pharmacokinetic study of the serum zinc profile after oral administration of a pharmacological dose of the metal, i.e. 0.69 mmol (45 mg) zinc as ZnSO4.7 H2O. The adopted experimental conditions include frequent measurements of serum concentrations, a total investigation time of 8 h after ingestion, and a correction of basal zinc levels taking into account the circadian variation. Rebound effects were evidenced in the time versus concentration curves showing a regular recycling of the element in the digestive tract. Estimation of the parameters by an original method allowed us to calculate the characteristics of the cycles. The first one occurred after 1.4 h, before the time needed for appearance of the maximum concentration which was around 2.3 h, and exhibited mean reabsorption of 70% of administered dose. The subsequent ones, maximum 5 during the investigation period, appeared at regular intervals of approximately 1.2 h, with a decrease in the quantity reabsorbed. These observations are consistent with the previously reported endogenous secretion of zinc, a physiological mechanism contributing to zinc homeostasis.

Absorption↗
PubMedDate not supplied

Effects of selenium supplementation on immune parameters in gut failure patients on home parenteral nutrition.

The relationships between some parameters of the immune response and selenium were investigated in five patients receiving home parenteral nutrition for short-bowel syndrome. They were first submitted to a relative depletion by providing 20 micrograms selenium/day as L-selenomethionine for 1 mo. Then, daily selenium intake was raised to 200 micrograms for 2-4 mo. On entering the study, the patients presented a relatively good health status, and immunological parameters were at the lowest limit of the normal range. Four patients rapidly responded to the 200-micrograms supplementation by a continuous increase in their plasma selenium levels, whereas the fifth patient showed a moderate and late increase. At the end of the trial, there was an improvement in the lymphocyte response to pokeweed and phytohemagglutinin mitogens in four patients and to CD3 in three patients. The response to two of three antigens (Candidin, Varidase) tested was also enhanced in the same patients, but the response to the third antigen (tetanus toxoid) was uniformly low in all patients. The only patient showing essentially no immune improvement after selenium supplementation was the one with a low and delayed increase in plasma selenium. This study supports a role for selenium in the maintenance of an optimal immune response in humans.

Aged↗
PubMedDate not supplied

[Intake of essential trace elements (selenium, copper and iron) in the nutrition of patients hospitalized with liver cirrhosis].

Dietary intake for three essential trace elements: selenium, copper and iron was studied in hospitalized patients receiving either ordinary meals or regimens adapted for liver cirrhosis. The aim of the study was to assess the effects of dietary manipulations: reduction in sodium intake for uncomplicated disease and protein restriction to 40 g per day in patients with hepatic encephalopathy. The meals proposed to these three groups were collected during fourteen days and daily intake for three elements was estimated by direct analysis of the assembled meals of the day. Dietary selenium was greatly affected by the restriction in protein intake contrary to copper and iron which were not significantly reduced. Moreover, overall daily trace element intake was rather low and clearly less than the most recent recommended allowances for these essential elements. Relationships between deficiency in some of these trace elements and worsening of the liver disease have been partly documented. They should encourage studies on the correction of dietary intake.

Copper↗