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Biomedical subjects

O Guillard

Publications and source records attributed to O Guillard.

At least 19 recordsLinked to original sources
PubMed2006

Heterogeneous colonization pattern of European Cyprinids, as highlighted by the dace complex (Teleostei: Cyprinidae).

The dace (Leuciscus leuciscus), with a very large geographic distribution all over Europe, represents an interesting species model for studies of the global mechanisms underlying aquatic system biodiversity. To assess the congruence with the past colonization process hypothesis of the freshwater fauna in Western Europe, we investigated the evolutionary history of this species, by integrating morphological variation (eight meristic characters), mitochondrial (cytochrome b, 16S rDNA and control region, over a total of 2169 bp) and nuclear (12 allozymes loci) phylogenetic relationships, and investigating population dynamics via expansion, migration, bottleneck, and divergence time analyses. We carried out nested clade phylogeographic analysis for a total of 663 specimens from 31 populations taken from all over the distribution area. Unlike previous studies, we found that L. leuciscus is currently constituted by five lineages belonging to two clades (yielding 6.3% of pairwise divergence). The relationships between these lineages were accounted for by complex biogeographical patterns due to Pliocene and Pleistocene paleoclimatic events, validating the identification of new glacial refuges for freshwater fish in Western Europe. Finally, we demonstrated hybridization between L. leuciscus and Leuciscus idus.

Animal Migration↗
PubMed2005

Nickel-elicited systemic contact dermatitis from a peripheral intravenous catheter.

Nickel-elicited systemic contact dermatitis is a well-known entity, although it is far less common than allergic contact dermatitis. In most of the cases, the main way of nickel administration is oral. Clinical manifestations are miscellaneous including pompholyx, diffuse exanthema, flexural dermatitis or baboon syndrome. Systemic nickel dermatitis induced by venous catheters is very uncommon, but it is probably underdiagnosed. We report here 2 patients with diffuse recurrent maculopapular rash corresponding to nickel-elicited systemic contact dermatitis. They were both perfused during the last episode with the assistance of a peripheral polyurethane venous catheter during or just before the cutaneous eruption. At the base of the catheter, there was a small metallic eyelet on which dimethylglyoxime test was positive, indicating a release of nickel. Then, we measured nickel release in normal use conditions and found high nickel levels, although the manufacturer denied that nickel could be released. This diagnosis is important to know because such exanthema often occurred during postoperative or postpartum period. Its frequency is probably underestimated because it is often considered as a cutaneous drug reaction. To our knowledge, only 2 cases have been reported in the literature.

Adult↗
PubMed2001

Ultrastructural study of rat hippocampus after chronic administration of aluminum L-glutamate: an acceleration of the aging process.

An ultrastructural study of rat hippocampus was performed on young (group 1) and old (group 4) rats receiving daily subcutaneous injections of aluminum L-glutamate and on old untreated rats (group 5). Young controls were treated with sodium L-glutamate (group 2) and physiological saline (group 3). Group 1 showed vacuolated astrocytes with numerous lipofuscin deposits, mitochondrial swelling, a thinning of the myelin sheath, and many multivesicular bodies invading the cytoplasm. Cellular structure did not appear to be affected in groups 2 and 3. Group 4 showed swollen mitochondria, a demyelination process in axonal regions, sizable perivascular oedema with vessel retraction and gliofilament bundles. In this group, lipofuscin deposits in astrocytes were associated with multivesicular bodies that thinned the myelin sheath to the breaking point; however, no excitotoxic glutamate-induced effects were observed. In group 5, extreme cytoplasmic vacuolation was observed, with massive mitochondrial swelling, considerable thinning of the myelin sheath (at times to the breaking point), sizable vacuolar degeneration and gliofilament bundles. These results indicate that ultrastructural alterations in the hippocampus, such as cell vacuolization, massive mitochondrial swelling and the demyelination process, occur with aging and independently of aluminum intoxication. Similar alterations were observed in aluminum L-glutamate-intoxicated young rats, but not in controls. These results are consistent with aluminum-induced acceleration of the aging process.

Aging↗
PubMed2000

Effects of aluminum exposure on glutamate metabolism: a possible explanation for its toxicity.

The effects of aluminum (Al) exposure on glutamate metabolism were investigated to study the mechanism of Al toxicity in rat brain. In astrocytes, the glutamate-glutamine pathway prevents the accumulation of the excitatory neurotransmitter glutamate, recognized as a neuronal excitotoxin when present in excess in the extracellular space. Changes in the level of l-aspartate, l-glutamate, and its metabolite l-glutamine were investigated in various regions of rat brains following intraperitoneal injection of aluminium gluconate for 2 months. The changes observed were area- and amino-acid-specific. An increase in glutamine, but not in l-glutamate or l-aspartate, was noted in the hippocampus and neocortex of Al-treated rats. This increase in vivo was consistent with observations in vitro. Exposure of cultured astrocytes to Al chloride (200, 400, and 800 microM) specifically increased glutamine synthetase activity for the three concentrations tested. In parallel with this increase, a higher rate of disappearance of glutamate from culture medium was observed during the first 10 min of incubation for the three concentrations tested, as well as an accumulation of glutamine in the cellular extract after 30 min. These observations indicate that the astrocyte population is a potential target for Al toxic action that could mediate the pathogenesis of this metal.

Aluminum↗
PubMed1999

Chronic administration of aluminium L-glutamate in young mature rats: effects on iron levels and lipid peroxidation in selected brain areas.

Clinical and experimental studies have demonstrated the neurotoxicity of aluminium (Al), notably as a result of lipid peroxidation in vitro. We previously showed that Al is able to cross the blood-brain barrier as an L-glutamate complex and be deposited in rat brain. The present work in young mature rats investigated the in vivo effects of chronic Al-L-glutamate treatment on Al and iron movement in plasma and selected brain regions. Brain lipid peroxidation was determined by evaluating the production of thiobarbituric acid reactive substances (TBARS) and analysing polyunsaturated fatty acids (PUFAs) such as C20:4n-6 and C22:6n-3. Our results indicate that iron concentration was decreased in plasma and that Al accumulated especially in striatum where iron levels were decreased and in the hippocampus where TBARS were increased without PUFA modifications. These data show that Al administered chronically as an L-glutamate complex is neurotoxic in vivo and thus provides a good model for studying Al toxic mechanisms.

Aluminum↗
PubMed1999

[Chronic lead poisoning in children today. A pathology of poverty and social exclusion].

Despite the recognition of lead poisoning in children as a major public health problem in France since the 1980's, the setting-up of systematic detection of lead poisoning at a national level has not yet been done. The main source of intoxication in children is in paintings containing ceruse in housing built before 1948. Moderate chronic poisoning, although leading to irreversible lesions, particularly of the central nervous system, remains usually unnoticed. The biological diagnosis is mainly based upon blood lead level, completed by the protoporphyrine-zinc level. Large scale identification of dangerous housing and the control of rehabilitation are the only means available to decrease the incidence of lead posioning. Targeted screening is difficult because it concerns children excluded from classical health care systems. Prevention and long-term treatment requires elimination of the source of lead intoxication after an environmental inquiry. This raises the problems of rehousing and follow-up of intoxicated children.

Child↗
PubMed1997

Biological levels of aluminium after use of aluminium-containing bone cement in post-otoneurosurgery.

Use aluminium-containing biomaterials in otoneurosurgery for reconstitution of bone in contact with cerebrospinal fluid (CSF) also led to cases of encephalopathy and death. We report aluminium (Al) concentrations in the biological fluids of six French patients following use of Al-containing bone cement in otoneurosurgery. In five patients, the mean plasma Al levels (microgram/L) were: 1.20 +/- 0.05 (case 2), 9.20 +/- 0.10 (case 3), 1.00 +/- 0.05 (case 4), 2.80 +/- 0.05 (case 5) and 2.00 +/- 0.05 (case 6). In case 1, Al concentrations were 176 micrograms/L in the postauricular CSF accumulation, 34 micrograms/L in the pontocerebellar angle and 4 and 6 micrograms/L in the lumbar shunt. As a precautionary measure, in the first three cases the biomaterial was removed soon after the intervention, and no increase in plasma or CSF Al was observed. In the other cases, absence of neurobiological symptoms and normal concentrations of Al in plasma led neurosurgeons not to extract this biomaterial. Al assay thus may be considered to be a complementary and at times a decision-generating factor. Care is needed at all stages from sampling through analysis because Al is ubiquitous and factually high results may be clinically misleading. Herein, such considerations are discussed in conjunction with the neurotoxicity of this metal in man. In addition, the authors call for in-depth preliminary trials of these biomaterials in animals prior to introduction on the market.

Adult↗
PubMed1997

In vitro study of the antiseborrheic activity of zinc L-cysteate, a novel zinc compound, on rat preputial gland.

The antiseborrheic effect of zinc L-cysteate, a new zinc compound, was evaluated in vitro by determining the lipidic metabolic activity of rat preputial glands as measured by incorporation of 14C-sodium acetate. At 10(-3) and 10(-4) mol/l, zinc L-cysteate was more active than S-carboxymethyl L-cysteine used as reference in corresponding concentrations (p < 0.05 and p < 0.01, respectively). The pharmacologic results seem promising for clinical studies in dermatology.

Animals↗
PubMed1996

Absence of gastrointestinal absorption or urinary excretion of aluminium from an allantoinate complex contained in two antacid formulations in patients with normal renal function.

We studied the plasma and urinary excretion levels of aluminum (Al) on day 0, 10 and 30 in 79 patients with gastrointestinal symptoms and normal renal function who were receiving a complex based on Al allantoinates [C4H5N4 O3 Al (OH)2] and [C4H5N4 O3 Cl Al2 (OH)4]. We evaluated the extent of Al absorption after repeated administration of this complex in two antacid formulations, Ulfon Lyoc in lyophilised tablet form (group 1; n = 40) and Ulfon suspension (group 2; n = 39). The total Al load for each antacid and patient was 512 mg daily for a total of 15360 mg during the 30-day treatment. No significant rise in plasma Al concentration was noted with either formulation between day 0 and 10, day 0 and 30 or day 10 and 30, nor was there any significant increase in urinary excretion levels. Al absorption was not increased and no toxic effects were noted, indicating that such formulations are suitable for long-term therapy in patients with gastrointestinal symptoms.

Adult↗
PubMed1996

French external quality assessment schemes for lead in blood and aluminum in plasma and dialysis water.

An external quality assessment scheme (EQAS) for lead in blood was established in France in 1992 at the request of the Ministry of Labour and organised by the Drug Bureau. Participation is mandatory for laboratories wishing to obtain ministerial approval for the determination of blood lead levels. In 1994, two interlaboratory comparative exercises were carried out, each involving the analysis of 3 samples of human blood (2 with and 1 without lead supplementation). Out of 66 enrolled laboratories, 58 and 60 participated in the two exercises, respectively. The scattering of results was quite comparable to that observed in other EQAS. The EQAS for plasma aluminium was established in 1983 at the request of the Commission on Trace Elements of the Société Française de Biologie Clinique. Today, 80 laboratories in 22 countries on 4 continents participate in this scheme. Six exercises are carried out each year, each including 3 plasma samples (2 with and 1 without aluminium supplementation), 2 samples of water supplemented with aluminium and a blank (water). The results obtained in this scheme showed an improvement in the quality of the analyses.

Aluminum↗
PubMed1994

[Practical advice concerning biological fluids for analysis of trace-elements].

Sampling conditions are of utmost importance for the determination of trace elements in biological fluids. However, many biologists still underevaluate this critical step. This reports deals with collection of biological fluids from a routine point of view: detailed and careful descriptions of the contaminating role of air and the general handling of specimens are given in a practical and critical manner. The main commercial systems, made about needles, catheters, tubes (open and evacuated systems) and anticoagulants are reviewed. Choices and elementary rules, applicable in a hospital setting, are proposed.

Air Pollutants, Occupational↗
PubMed1993

An evaluation of the biological significance of aluminium in plasma and hair of patients on long-term hemodialysis.

In hemodialyzed patients, the risk of toxicity attributed to the body accumulation of aluminium (Al) justifies the need for monitoring Al in various human media. In this study, Al concentrations in the hair and plasma of 78 hemodialyzed patients with chronic renal failure and of 351 healthy volunteers were measured by electrothermal atomic absorption spectrometry with Zeeman effect. Plasma Al concentrations in patients were significantly higher than in the controls and positively correlated with time on dialysis. Hair Al levels were widely distributed with no significant distinction between patients and controls. On the subject of establishing correlation, the authors stress the importance of taking into account the kinetics of the elimination of minerals from hair. Even when this was done, in the patient group there was no statistical link between plasma and hair Al levels. Hair Al analysis is of no value as an indicator of body Al accumulation.

Adolescent↗
PubMed1993

Sampling conditions for biological fluids for trace elements monitoring in hospital patients: a critical approach.

Lack of coherence in the results of trace element (TE) analyses produced by various laboratories has been such as to necessitate much needed technical improvements and more detailed control over sample preparations. For too long, except for a few praiseworthy researchers, the importance of sampling conditions has been underestimated as a source of erroneous TE results. Many of the precautionary procedures for previously studied TE collection materials have proven to be so cumbersome that they cannot be applied in a hospital setting. This report deals with sampling material and conditions from a workday standpoint; a rigorous description of the contaminating roles of ambient air and routine handling of specimens places emphasis on the practical. While some metals, including cobalt, copper, iron, and selenium, present no significant risk of contamination, others, such as aluminum, cadmium, chromium, manganese, and nickel, pose quite a significant risk. They warrant attention with respect not only to the sampling itself but also the selection of the material to be used. Drawing on our hospital experience, we propose a critical approach toward the collection of samples of biological fluids (blood, urine, dialysis fluids). Needles, catheters, tubes (open and evacuated systems), and anticoagulants on the market are likewise assessed in terms of their contaminative roles. For each one elementary rules as well as realistic choices of materials and methods for a hospital environment are proposed.

Body Fluids↗
PubMed1993

Iron- and lactic acid-induced lipid peroxidation in rat kidney homogenates and slices.

Lactic acid 4 mM acted as a lipoperoxidant by increasing production of thiobarbituric acid-reactive substances (TBARS) in rat kidney slices and homogenates. This effect occurred mainly when slices and homogenates were incubated in a pH 5.4 medium conductive to full expression of compound acidity. TBARS increase was only slight when incubation was performed in Krebs buffer, pH 7.4. Moreover, sodium lactate 4 mM increased TBARS production only when homogenates were incubated in the pH 5.4 medium. Deferoxamine (1 mM) inhibited the prooxidant effect of lactic acid 4 mM, and TBARS increase was correlated with iron release. The iron mobilized may come from reserves where it is weakly bound or from ferritin; and ascorbic acid, present in low quantities in kidney, might trigger the release of this product.

Animals↗
PubMed1992

Congenital hypomagnesemia: alternatives to tissue biopsies for monitoring body magnesium status.

We have been monitoring a 12-year-old boy (his present age) suffering from selective magnesium (Mg) malabsorption. After ascertaining his Mg status, we attempted to maintain Mg balance through the use of oral supplements. Plasma and erythrocyte Mg concentrations were monitored at bimonthly intervals. However these measurements did not accurately reflect Mg status and we subsequently measured Mg in the following tissues: lymphocyte, tooth, and hair. Levels of Mg in stable tissues such as temporary teeth and lymphocytes, unfailingly revealed a marked deficit in Mg that was only two-thirds of the normal levels found in the control group. The use of these readily-accessible stable tissues can thus obviate the need for muscle or bone biopsy. Unfortunately the level in hair is higher than in healthy subjects, and thus does not constitute an adequate measure of Mg status.

Child↗