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Biomedical subjects

A Bernard

Publications and source records attributed to A Bernard.

At least 523 records · Page 29Linked to original sources
PubMed1986

[Biological aspects of occupational exposure to cadmium and several other metals].

We have performed several cross-sectional epidemiological surveys among workers exposed to cadmium, mercury vapour or manganese in order to assess : their early biological or functional effects; the biological tests allowing an assessment of the amount of metal absorbed or stored in the body; the acceptable exposure levels. Studies have also been carried out among persons exposed to inorganic arsenic in order to define its inactivation mechanism and to develop a biological test of exposure. The kidney is the main critical organ following long-term exposure to cadmium. To prevent the occurrence of renal changes in the majority of male workers exposed to cadmium, its concentration in renal cortex should not exceed 215 micrograms/g (wet weight), and that in urine : 10 micrograms/g creatinine. A blood cadmium level of 1 microgram/100 ml has been suggested as maximum tolerable level for long-term exposure. Prolonged exposure to mercury vapour may lead to renal and neurological disturbances. The preclinical signs of nephrotoxicity are correlated with the amount of mercury absorbed which may be assessed by monitoring the mercury level in urine. The neurotoxic effects (particularly tremor) are mainly related to the integrated exposure (duration and intensity). A maximal permissible level of 50 micrograms Hg/g urinary creatinine is proposed to prevent the occurrence of these toxic effects. An exposure to manganese dust for 7 years on the average at a level below the maximum allowable airborne concentration (5 mg/m3) recommended by the ACGIH in the USA may still lead to a slight reduction in psychomotor and spirometric performances and interfere with calcium metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Arsenicals↗
PubMed1985

Preclinical toxic effects of manganese in workers from a Mn salts and oxides producing plant.

The results of the present epidemiological study among 141 workers (mean age: 34 years) from a Mn salts and oxides producing plant in Belgium suggest that preclinical perturbations (lung function, CNS, biological parameters) may occur in subjects exposed to airborne Mn levels (7 years on the average) usually lower (total dust, geometric mean about 1 mg/m3, 95th percentile 3.3 mg/m3) than the levels actually (5 mg/m3) tolerated.

Adult↗
PubMed1985

Surveillance of workers exposed to mercury vapour:validation of a previously proposed biological threshold limit value for mercury concentration in urine.

A cross-sectional epidemiological study was carried out among subjects exposed to mercury (Hg) vapour, ie, a group of 131 male workers (mean age: 30.9 yr; average duration of exposure, 4.8 yr) and a group of 54 female workers (mean age, 29.9 yr; average duration of exposure 7 yr). The results were compared with those obtained in well-matched control groups comprising 114 and 48 male and female workers, respectively. The intensity of current Hg vapour exposure was rather moderate as reflected by the levels of mercury in urine (HgU) (mean and 95th percentile: males 52 and 147 micrograms/g creatinine; females 37 and 63 micrograms/g creatinine) and of mercury in blood (mean and 95th percentile: males 1.4 and 3.7 micrograms/dl; females 0.9 and 1.4 microgram/dl). Several symptoms mainly related to the central nervous system (memory disturbances, depressive feelings, fatigue, irritability) were more prevalent in the Hg-exposed subjects. They were, however, not related to exposure parameters. In both male and female Hg-exposed workers no significant disturbances were found in short-term memory (audioverbal), simple reaction time (visual), critical flicker fusion, and colour discrimination ability. Only slight renal tubular effects were detected in Hg-exposed males and females, ie, an increased urinary beta-galactosidase activity and an increased urinary excretion of retinol-binding protein. The prevalence of these preclinical renal effects was more related to the current exposure intensity (HgU) than to the duration of exposure and was detected mainly when HgU exceeds 50 micrograms/g creatinine. Changes in hand tremor spectrum recorded with an accelerometer were found in the Hg-exposed males only. The prevalence of abnormal values for some hand tremor parameters (total velocity and total displacement in the 2-50-Hz band) was mainly increased in male workers exposed for more than 10 yr. Unlike the renal tubular effects, the preclinical signs of tremor were more related to the integrated exposure than to the current exposure. Since the female workers, who have been exposed to Hg vapour levels usually insufficient to increase their HgU levels above 50 micrograms/g creatinine, did not exhibit any change in hand tremor pattern, the results of the present study tend to validate our previously proposed biological threshold limit value of a HgU of 50 micrograms/g creatinine for workers chronically exposed to mercury vapour.

Belgium↗
PubMed1985

Environmental exposure to cadmium and renal function of elderly women living in cadmium-polluted areas of the Federal Republic of Germany.

An epidemiological study was performed to assess whether environmental pollution by cadmium as found in cadmium-polluted areas of the Federal Republic of Germany is associated with an increased prevalence of biological signs of kidney dysfunction in population groups non-occupationally exposed to heavy metals. The study was run in two industrial areas known to be highly contaminated by cadmium, lead and other heavy metals, viz. Stolberg and Duisburg. Düsseldorf was selected as a reference area. As a study population we selected 65- and 66-year-old women (n = 286) who had spent the major part of their lives in one of these areas. The average cadmium levels in blood (CdB) and urine (CdU) revealed significant differences in exposure to cadmium in the order Stolberg greater than Duisburg greater than Düsseldorf. Serum creatinine levels were, on average, significantly higher in the Stolberg group than in the Duisburg and Düsseldorf groups. However, with respect to the urinary excretion of low molecular weight proteins (beta 2-microglobulin, retinol-binding protein), albuminuria, total proteinuria, aminoaciduria, phosphaturia and some other biological findings, no significant differences between the study populations were noted. Similarly, the prevalence of clinically-confirmed hypertension as well as the relative frequency of hypertensive subjects (systolic greater than or equal to 160 and/or diastolic greater than or equal to 95 mm Hg) did not differ significantly among the three study groups. There was no exposure-response relationship between CdU and tubular proteinuria in the range of the CdU-levels found (0.1 to 5.2 micrograms/g creatinine). However, albuminuria tended to be increased at CdU levels greater than 2 micrograms/g creatinine.

Aged↗
PubMed1985

Influence of the diet on the portal and lymph transport of decanoic acid in rats. Simultaneous study of its mucosal catabolism.

The absorption route of decanoic acid, a medium chain fatty acid, infused in the intestinal lumen in the presence and absence of long chain fatty acids, has been analyzed. Ex vivo perfusion of isolated intestinal loop and intestinal lymph fistula was the technique used. Decanoic acid infused alone was essentially transported through the portal system. If infused in association with monopalmitin, oleic or palmitic acid, up to 3% of decanoic acid could be diluted in the lymph. Moreover, decanoic acid oxidation by the mucosa increased significantly with palmitic acid and in contrast decreased with oleic acid. These data show that both intestinal absorption processes and mucosal oxidation of the medium chain fatty acids are modulated by the lipid components of the diet.

Animals↗
PubMed1985

Inhibition of protein synthesis and intestinal absorptive cell ultrastructure in cycloheximide or puromycin-treated rats.

Inhibitors of protein synthesis are useful for the investigation of some aspects of intestinal fatty acid absorption. The aim of the present study was to investigate both the biochemical and morphological effects of two inhibitors of protein synthesis on the intestinal mucosa of adult rats. Our results showed that 4 or 4 1/2 h after a single dose of cycloheximide or multiple doses of puromycin, the inhibition of protein synthesis in the jejunal mucosa, measured by the incorporation of 14C-leucine, stabilized at 60% of the controls. At the same time, these two drugs had different effects on absorptive cell morphology: cycloheximide definitely altered the apical surface of these cells, disorganizing their cytoplasm; puromycin did not modify brush border morphology but remodeled the mitochondria and the Golgi complexes.

Animals↗
PubMed1985

[Biological monitoring of exposure to industrial toxic substances. Present-day situation and prospects for development].

Biological monitoring of exposure to an industrial chemical may be defined as the evaluation of the internal dose (internal exposure) by a biological method with the view of assessing the associated health risk. Depending on the biological parameter selected and on the time of sampling, internal dose may mean the amount of chemical recently absorbed, the amount stored in one or several compartments of the organism, or, under ideal conditions, the amount bound to the sites of action. The estimation of the internal dose has usually relied on two categories of tests: those based on the determination of the chemical and/or its metabolites in various biological media (eg, alveolar air, blood, urine) and those based on the quantification of a nonadverse biological effect, the intensity of which is related to the internal dose. Biological tests providing information on the amount of active chemical bound to the critical sites of action (target dose) and noninvasive analytical methods which measure the amount of cumulative toxins stored in certain body compartments (eg, bone, liver, kidney) are currently being developed. The main criteria to be considered in the selection of the most appropriate biological monitoring test of exposure are the specificity of the parameter and its sensitivity with respect to the exposure level, the analytical and biological applicability, the convenience for the workers, the possible risks associated with its application, and, of course, the accuracy of the exposure and/or health risk evaluation. Normally, the biological approach of exposure monitoring is reserved for chemicals which enter the organism and may exert systemic toxic effects. When a biological monitoring test of exposure is applicable, it offers several advantages over ambient air monitoring. A biological parameter reflecting the internal dose is necessarily more closely related to the systemic adverse effect(s) than any environmental measurement. Biological monitoring of exposure integrates the exposure by all routes (pulmonary, oral, and cutaneous) and sources. It may also take into account several factors which determine the uptake and the absorption of the chemical (individual variability, work load, hygiene habits, etc). However, contrary to ambient monitoring, biological monitoring is applicable only when sufficient information has been gathered on the metabolism of the chemical, its toxicity or that of its metabolites, and when some of the relationships between external exposure, internal dose and adverse effects have been assessed.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1985

T cell activation via CD2 [T, gp50] molecules: accessory cells are required to trigger T cell activation via CD2-D66 plus CD2-9.6/T11(1) epitopes.

Binding monoclonal antibodies (MAb) both to D66 and 9.6/T11(1) epitopes on the CD2 [T,gp50]-defined molecule produces a high level of T cell mitosis. This was observed with a battery of MAb of different isotypes. In contrast, none of the anti-D66 or anti-9.6/T11(1)Ab could trigger T cell proliferation in combination with anti-T11(3). Moreover, all anti-D66-9.6/T11(1) pairs of MAb tested required monocytes to activate T cells which were recruited through their Fc receptors. Variations among normal individuals were observed in the level of response to anti-D66-9.6/T11(1) pairs of Ab, 75% of a population of French Caucasians giving a high response. The level of response of a given individual was determined by his accessory cells. However, the level of response of an individual appeared to be minimally influenced by the isotype of a peculiar anti-D66 or anti-9.6/T11(1) Ab. The addition of exogeneous IL 2 could overcome the removal of accessory cells or the modulation of CD3 molecules. In contrast, IL 2 receptor appearance was not overcome by removal of monocytes. Thus, T cell activation via CD2 seems to be produced by "touching" several definite regions of this molecule which trigger a cascade of events similar to those produced by mitogenic lectins. One can assume that the appropriate conformational changes of the CD2 molecule induced by anti-D66-9.6/T11(1) pairs of Ab are solely produced when they are presented by accessory cells. This leaves open the question of whether accessory cells would also play a more active role.

Antibodies, Monoclonal↗
PubMed1985

Kidney disorders and hematotoxicity from organic solvent exposure.

Short-term exposure to certain solvents, such as several halogenated hydrocarbons, petroleum distillates, ethylene glycol, ethylene glycol ethers, and diethylene glycol, may cause renal tubular necrosis. Tubular lesions with metabolic acidosis have been reported in addicts inhaling solvent vapor (eg, toluene). A Goodpasture's syndrome may be induced by acute or subacute exposure to solvents, but its incidence is rare. No adequate proof is yet available that repeated exposure to nonsubstituted organic solvents may lead to the development of different types of chronic glomerulonephritis, but the available epidemiologic data are suggestive of the existence of such an association. Only a few solvents have been reported to act on the hematopoietic system of humans. The hematotoxicity (aplastic anemia, leukemia) of benzene is well established. Some ethylene glycol ethers are also toxic to bone marrow.

Adult↗
PubMed1985

[Tubular involvement during non-oliguric rhabdomyolysis. (Apropos of 2 cases)].

The authors report two cases of severe rhabdomyolysis in a 23-year-old woman following a toxic coma with muscular compression and in a 34-year-old man after a febrile state. Despite clinical and biological signs of marked muscular necrosis, oliguric acute renal failure did not occur. However, repetitive urinary dosage of N-acetyl-glucosaminidase (NAG), of retinol-binding-protein (RBP) and of beta-2-microglobulin (beta-2-m) revealed an early and long-standing tubular dysfunction not suggested by conventional laboratory data.

Acetylglucosaminidase↗
PubMed1985

[Urethral duplication in boys. Apropos of 2 cases].

The duplication of the urethra is a rare but well described anomaly. The authors report two more cases which contribute to illustrate the classification and the problems met in this condition. The classification proposed by D.I. Williams and M.M. Kenawi has been adopted. They distinguish 5 types of urethral duplications: epispadiac, hypospadiac (complete or incomplete forms), spindle urethra, bifid urethras (H-type) with an accessory pre-anal branch, and finally collateral duplications. The first reported case is a complete epispadial duplication type. The second case is a incomplete hypospadial duplication type, associated with late complications due to the unrecognized valve effect by the mucosal folds at the junction between the two urethras. The diagnosis, the treatment and the embryology are discussed in both cases.

Child, Preschool↗
PubMed1985

[Nuclear magnetic resonance. A technic of the future].

Nuclear magnetic resonance, a technique in its early stages in the field of proton imaging, appears to be very promising. It is capable of yielding not only morphological information, but also dynamic and metabolic information.

Humans↗
PubMed1985

Effect of progesterone treatment near term on the onset of labour in rats.

The effect of systematically delayed progesterone treatment on the onset of labour was examined in 45 pregnant rats. Measurement of progesterone (P) and prostaglandin F (PGF) in uterine vein plasma and uterine tissue before and during spontaneous labour or during prolonged pregnancy showed that the control animals exhibited the expected P-withdrawal (Pw) prior to spontaneous labour, however, properly timed P-treatment predictably prevented Pw and labour. When P was administered 11.7 +/- 2.8 hours before spontaneous labour, the animals delivered normally, despite increased plasma and tissue P-levels. These observations show that P-concentration cannot be equated to P-action.

Animals↗
PubMed1985

[Biological markers of exposure to toxic agents].

Exposure to chemical agents may be assessed either qualitatively or semi-quantitatively with the help of a questionnaire (type of exposure and duration) or quantitatively either by the measurement of the concentration of the xenobiotics in the environment (ambient monitoring) or by the measurement of biological parameters related to the internal doses (biological monitoring of exposure). In industry, ambient monitoring usually implies the measurement of chemicals in air with static or personal samplers. The internal doses may be assessed either by measuring the chemical or its biotransformation products in biological media or by measuring some biological effects caused by the chemical. Depending on the selected biological parameter and the time of sampling, the result may reflect the amount of chemical recently absorbed, the amount stored in the organism (body burden) or the amount of active metabolites bound to the site of action. The biological parameter of exposure is more directly related to the adverse health effects that one attempts to prevent than any environmental measurement. Biological monitoring may take into consideration absorption by all the routes and from all sources (occupational and environmental), interindividual differences in toxicokinetic and in hygiene habits. The application of a biological test requires the critical evaluation of several factors, namely the sensitivity and the specificity of the test, the precision and the accuracy of the analytical method and eventually ethical aspects.

Biotransformation↗