Search PubMed⌕ Search

Biomedical subjects

M Clément

Publications and source records attributed to M Clément.

At least 19 recordsLinked to original sources
PubMed2005

[Hypertension revealing aneurysmal renal fibrodysplasia].

A 20-year-old woman consulted for severe hypertension which revealed aneurismal stenosing fibrodysplasia of the renal arteries. The diagnosis was established by duplex Doppler which visualized tight stenosis of the distal portion of the right renal artery and the proximal portion of the left, associated with aneurismal lesions downstream from the strictures (1.8 cm on the right and 1.3 cm on the left). The lesions were highly suggestive of fibrodysplasia and were confirmed by magnetic resonance angiography. Endoluminal revascularization was undertaken because of the severe hypertension and the presence of arterial lesions. Revascularization was unsuccessful and severe hypertension persisted. Surgery was performed in two stages. The first procedure consisted in resection of the left aneurismal lesion with aortorenal internal saphene bypass. Secondarily, exclusion of the right aneurysm was performed with cure of the stricture by extracorporal renal surgery with anastomosis of the renal artery to the aorta and the renal vein to the vena cava. Clinical outcome was favorable. Angioscan and duplex Doppler controls at three and six months confirmed the anatomic success of the revascularization. Aneurysm of the renal artery, like renal artery stenotic dysplasia, is a rare but probably underestimated condition due to insufficient screening. This diagnosis should be entertained in hypertensive young women. There is risk of rupture of the aneurysm. Aneurysmal lesions can be associated with renal artery stenosis which usually involves a short segment of the artery, as in our case. Renal aneurysms should be treated when one of the following elements is present: aneurysm measuring more than 20 mm, progressing aneurysm, dissection, discovery in a patient with a renal risk (single kidney, renal insufficiency), desire for pregnancy, severe hypertension recently discovered in a young subject associated with dysplastic stenosis, isolated aneurysm associated with recent severe hypertension, as reported here.

Adult↗
PubMed2002

Docosahexaenoic acid-rich phospholipid supplementation: effect on behavior, learning ability, and retinal function in control and n-3 polyunsaturated fatty acid deficient old mice.

This study investigated the effects of docosahexaenoic acid (DHA)-rich phospholipid supplementation on behavior, electroretinogram and phospholipid fatty acid (PUFA) composition in selected brain regions and retina in old mice. Two groups of mice were fed a semisynthetic balanced diet or a diet deficient in alpha-linolenic acid. At the age of 8 months, half of each diet group was supplemented with DHA. In the open field, no differences in motor or exploratory activities were observed between the four diet groups. In the light/dark test of anxiety, the time spent in the light compartment was significantly higher in both supplemented groups than in control and deficient groups. Learning performance in the Morris water maze was significantly impaired in deficient old mice, but was completely restored by the phospholipid supplementation. The electroretinogram showed a significant alteration of a- and b-wave amplitudes in control compared to deficient mice. Phospholipid supplementation induced a significant increase of b-wave amplitude in both control and deficient groups and restored normal fatty acid composition in brain regions and retina in deficient mice. DHA-rich phospholipids may improve learning ability, visual function and reverse biochemical modifications in old mice fed an n-3 polyunsaturated fatty acid-deficient diet; they also may improve visual function in old mice fed a balanced diet.

Animals↗
PubMed2001

Molecular cloning of CaYRB1, the Candida albicans RanBP1/YRB1 homologue.

The yeast Ran binding protein 1 (Yrb1p) is a small protein of 23 kDa that is highly conserved among eukaryotes. It stimulates the GTPase activity of Gsp1p in the presence of the GTPase activating protein Rna1p. In addition to its role in nucleocytoplasmic transport of macromolecules, YRB1/RanBP1 could be involved in the regulation of microtubules structure and dynamics. Since microtubules are tightly associated with morphological changes, we have been interested to study the role and function of YRB1 in the pathogenic fungus Candida albicans, where there is regulated change in cellular morphology. The gene product of CaYRB1 encodes a 212 amino acid protein displaying 73% homology to the S. cerevisiae homologue. The bacterially expressed gene product has an apparent molecular weight of 35.7 kDa. We show that it can complement a S. cerevisiae yrb1 null mutant and that its mRNA does not appear to be regulated in response to conditions inducing morphological changes in C. albicans.

Amino Acid Sequence↗
PubMed2001

Overexpression of Bud5p can suppress mutations in the Gsp1p guanine nucleotide exchange factor Prp20p in Saccharomyces cerevisiae.

The gene product Prp20p, which is located in the nucleus, serves as the nucleotide exchange factor (GEF) for the small nuclear G protein Gsp1p in Saccharomyces cerevisiae, and catalyses the replacement of Gsp1-bound GDP by GTP. These proteins are involved in numerous cellular processes, including nucleocytoplasmic trafficking of macromolecules, cell cycle progression, DNA replication and maintenance of chromosome structure/stability. It is believed that in order to complete a full GDP/GTP cycle, Gsp1p has to shuttle between the nucleus and the cytoplasm, where its GTPase Activating Protein (GAP) Rna1p is located. Here, we report on the ability of Bud5p, the exchange factor for Rsr1p, to suppress conditional prp20 mutants when an extra copy of GSP1 is present. This suppression by BUD5 can be reversed by simultaneous overexpression of RNA1, and is not Rsr1p-dependent, nor allele-specific. We also show that Bud5p can physically interact with Gsplp, both in vitro and in vivo. These,findings raise the possibility that Bud5p could act as a cytoplasmic exchange factor for Gsp1p and, therefore, that a complete GDP/GTP cycle could take place in the cytoplasm.

Base Sequence↗
PubMed2001

ABH and Lewis histo-blood group antigens, a model for the meaning of oligosaccharide diversity in the face of a changing world.

Antigens of the ABH and Lewis histo-blood group family have been known for a long time. Yet their biological meaning is still largely obscure. Based on the available knowledge about the genes involved in their biosynthesis and about their tissue distribution in humans and other mammals, we discuss here the selective forces that may maintain or propagate these oligosaccharide antigens. The ABO, alpha 1,2fucosyltransferase and alpha 1,3fucosyltransferase enzyme families have been generated by gene duplications. Members of these families contribute to biosynthesis of the antigens through epistatic interactions. We suggest that the highly polymorphic genes of each family provide intraspecies diversity that allows coping with diverse and rapidly evolving pathogens. In contrast, the genes of low frequency polymorphism are expected to play roles at the cellular level, although they may be dispensable at the individual level. In addition, some members of these three gene families are expected to be functionally redundant and may either provide a reservoir for additional diversity in the future or become inactivated. We also discuss the role of the ABH and Lewis histo-blood group antigens in pathologies such as cancer and cardiovascular diseases, but argue that it is merely incidental and devoid of evolutionary impact.

ABO Blood-Group System↗
PubMed2001

ABH and Lewis histo-blood group antigens in cancer.

Antigens of the ABH and Lewis histo-blood group family can be found on many normal cells, mainly of epithelial type. In carcinomas, altered expression of the various carbohydrate epitopes of this family occur, and are often strongly associated with either a good or bad prognosis. A review of the available data on these tumor-associated markers, their biosynthesis and their prognostic value is proposed here. For a long time it has been unclear whether their presence could affect the behavior of carcinoma cells. Recent data, however, indicate that they play biological roles in the course of tumor progression. The presence of sialyl-Le(a) or sialyl-Le(x), which are ligands for selectins, promotes the metastatic process by facilitating interaction with the endothelium of distant organs. The loss of A and B antigens increases cellular motility, while the presence of H epitopes increases resistance to apoptosis by mechanisms that remain to be defined. The Le(y) antigen has procoagulant and angiogenic activities. All these observations are used to present a model that may account for the described associations between the presence or loss of these markers and the outcome of disease. Finally, their potential clinical applications as tumor-associated markers or as targets of immunotherapy are reviewed.

ABO Blood-Group System↗
PubMed2000

Vitamin E deficiency has different effects on brain and liver phospholipid hydroperoxide glutathione peroxidase activities in the rat.

The effect of vitamin E deficiency on glutathione peroxidase activity (GPX) and on the activity of a selenoenzyme (phospholipid hydroperoxide glutathione peroxidase (PHGPX) was measured in rat brain and liver. In brain, the activity of both enzymes was in the same range in homogenate and in microsomes. In contrast, in liver homogenate, PHGPX activity was approximately 20 times lower than that of GPX. Very interestingly, PHGPX activity was significantly decreased in brain microsomes by vitamin E deficiency, but slightly significantly increased in liver microsomes. In contrast, GPX activity was not affected in brain by vitamin E deficiency, but was significantly lower in liver homogenate and microsomes. Thus, PHGPX activity is partially controlled by vitamin E in membranes, and PHGPX is probably an enzyme different from GPX.

Animals↗
PubMed2000

Characterization of CaGSP1, the Candida albicans RAN/GSP1 homologue.

Gsp1p is a small nuclear-located GTP binding protein from the yeast Saccharomyces cerevisiae. It is highly conserved among eucaryotic cells and is involved in numerous cellular processes, including nucleocytoplasmic trafficking of macromolecules. To learn more about the GSP1 structure/function, we have characterized its Candida albicans homologue. CaGsp1p is 214 amino acids long and displays 91% identity to the ScGsp1p. There is functional complementation in S. cerevisiae, and its mRNA is constitutively expressed in the diploid C. albicans grown under various physiological conditions. Disruption of both alleles was not possible, suggesting that it could be an essential gene, but heterozygous mutants exhibited genomic instability.

Amino Acid Sequence↗
PubMed2000

Adsorption/thermal desorption-GC/MS for the analysis of pesticides in the atmosphere.

An analytical methodology using Automatic Thermal Desorption (ATD) and GC/MS was developed for the determination of the pesticides alachlor, atrazine, captan, formothion, lindane and phosalone in atmospheric samples. This methodology was developed to evaluate the atmospheric contamination by pesticides during treatments and by post-application. Atmospheric samples were collected by using (4 i.d. x 89 mm) stainless steel sampling tubes containing 125 mg of adsorbents at a flow rate of 80 ml min-1. Different types of adsorbents were tested for their ability to efficiently trap pesticides under study: Tenax TA, Carbopack Y, Carbopack B, Carbotrap, Carboxen, Chromosorb 106 and XAD-4. Results of experiment show that Tenax gives the better results for all the pesticides used but the use of the thermal-desorption method, especially for pesticides with low volatility and/or poor thermal stability presents some difficulties. This method was validated by the analysis of the contamination of atmosphere, through volatilization by post-application processes, of atrazine in a parcel of 1 ha.

Acetamides↗
PubMed2000

[Personal sports training in the management of obese boys aged 12 to 16 years].

OBJECTIVE: Estimation of both physical and psychological effects of an adapted physical training on children undergoing an obesity treatment. MATERIAL AND METHODS: The survey was carried out on 36 obese boys (ages = 12-16 years) who stayed in the medical center for at least four months. Eighteen of them were trained with the SELF method (the SELF-training is global, progressive, adapted to each boy, controlled and takes place within a ten-week period with five sessions a fortnight, each session lasting 30 to 40 minutes). The parameters that were studied concerned auxology, breathing function exploration, aerobic and anaerobic capacities, muscle strength and psychomotor qualities; the subjective effects of the training were estimated with a questionnaire about life quality, and the hand test. At inclusion the results were reported to a standard kind of population. At the end of the training the results of the 18 boys that were trained were compared to those of the 18 controls. RESULTS: Compared to a standard population, the obese children' aerobic capacity is diminished for the maximum power but is identical in absolute value for the VO2 max; their anaerobic capacities, muscle strength and psychomotor capacities are lower and their psyche is affected by the disease. After a three-month training period and after comparison with the 'control' group, there can be noticed a significant improvement in the psychomotor capacities, a major tendency for the improvement of the aerobic capacities and very positive effects on the psyche. CONCLUSION: SELF-training in association with dietetics appears to be very useful in the therapeutic care of obese children. For the follow-up at home it would need to be registered within the domain of physiotherapy.

Adolescent↗
PubMed2000

Specific phospholipid fatty acid composition of brain regions in mice. Effects of n-3 polyunsaturated fatty acid deficiency and phospholipid supplementation.

This study examined the effects of dietary alpha-linolenic acid deficiency followed or not by supplementation with phospholipids rich in n;-3 polyunsaturated fatty acid (PUFA) on the fatty acid composition of total phospholipids in 11 brain regions. Three weeks before mating, mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or deficient in alpha-linolenic acid. Pups were fed the same diet as their dams. At the age of 7 weeks, a part of the deficient group were supplemented with n;-3 polyunsaturated fatty acids (PUFA) from either egg yolk or pig brain phospholipids for 2 months. Saturated and monounsaturated fatty acid levels varied among brain regions and were not significantly affected by the diet. In control mice, the level of 22:6 n-3 was significantly higher in the frontal cortex compared to all regions. alpha-Linolenic acid deficiency decreased the level of 22:6 n-3 and was compensated by an increase in 22:5 n-6 in all regions. However, the brain regions were affected differently. After the pituitary gland, the frontal cortex, and the striatum were the most markedly affected with 40% reduction of 22:6 n-3. Supplementation with egg yolk or cerebral phospholipids in deficient mice restored a normal fatty acid composition in brain regions except for the frontal cortex. There was a regional distribution of the fatty acids in the brain and the impact of deficiency in alpha-linolenic acid was region-specific. Dietary egg yolk or cerebral phospholipids are an effective source of n-3 PUFA for the recovery of altered fatty acid composition induced by a diet deficient in n-3 PUFA.

Animals↗
PubMed2000

Phospholipid supplementation reverses behavioral and biochemical alterations induced by n-3 polyunsaturated fatty acid deficiency in mice.

This study investigated the effects of a diet deficient in alpha-linolenic acid followed or not by supplementation with phospholipids rich in n-3 polyunsaturated fatty acids (PUFA) on behavior and phospholipid fatty acid composition in selected brain regions. Three weeks before mating, two groups of mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or a diet deficient in alpha-linolenic acid. Pups were fed the same diet as their dams. At the age of 7 weeks, a part of the deficient group was supplemented with n-3 PUFA from either egg yolk or pig brain phospholipids for 2 months. In the open field, rearing activity was significantly reduced in the deficient group. In the elevated plus maze (anxiety protocol), the time spent on open arms was significantly smaller in deficient mice than in controls. Using the learning protocol with the same task, the alpha-linolenic acid deficiency induced a learning deficit. Rearing activity and learning deficits were completely restored by supplementation with egg yolk or cerebral phospholipids, though the level of anxiety remained significantly higher than that of controls. There were no differences among the 4 diet groups for either the Morris water maze or passive avoidance. In control mice, the level of 22:6 n-3 was significantly higher in the frontal cortex compared to all other regions analysed. The frontal cortex and the striatum were the most markedly affected by the deficiency. Supplementation with phospholipids restored normal fatty acid composition in brain regions except for frontal cortex. Egg yolk or cerebral phospholipids are an effective source of n-3 PUFA for reversing behavioral changes and altered fatty acid composition induced by a diet deficient in n-3 PUFA.

Animals↗
PubMed1999

Learning deficits in first generation OF1 mice deficient in (n-3) polyunsaturated fatty acids do not result from visual alteration.

The effects of (n-3) polyunsaturated fatty acids (PUFA) diet deficiency on learning, electroretinogram and retinal fatty acid composition were assessed for the first time in OF1 mice. Pups fed the same diets (deficient in alpha-linolenic acid or a control) as their dams were used aged 7 weeks for passive avoidance test and fatty acid analysis of retinal phospholipids. Visual function was measured by electroretinography in 4- and 7-week-old mice. The (n-3) PUFA-deficient diet significantly decreased learning performance and retinal docosahexaenoic acid level in adult mice. The electroretinogram showed a significant alteration of b-wave amplitude in deficient mice at 4 weeks but not at 7 weeks. These results show that learning deficits in mice fed a diet deficient in (n-3) PUFA were not due to visual alteration.

Animals↗
PubMed1998

Isolation and characterization of the Candida albicans SEC4 gene.

The SEC4 gene product is a major component of the protein secretion machinery. More specifically, it is believed to play a pivotal role in targeting and fusion of secretory vesicles to the plasma membrane. Its recently described implication with the Saccharomyces cerevisiae Rho3p, which is required for directing growing points during bud formation, has prompted us to investigate the role and function of Sec4p in the morphological changes of the yeast pathogen Candida albicans. We have therefore cloned the C. albicans SEC4 gene. It encodes a 210 amino acids long protein sharing up to 75% homology to the S. cerevisiae homolog, when conserved changes are allowed. Its RNA is constitutively expressed in C. albicans grown under various physiological conditions. We also show that it can functionally complement a S. cerevisiae sec4 thermosensitive mutant.

Amino Acid Sequence↗
PubMed1997

Graded dietary levels of RRR-gamma-tocopherol induce a marked increase in the concentrations of alpha- and gamma-tocopherol in nervous tissues, heart, liver and muscle of vitamin-E-deficient rats.

The effect of dietary RRR-gamma-tocopherol supplementation on serum and tissue alpha- and gamma-tocopherol concentrations was studied in vitamin-E-deficient rats fed diets containing adequate levels of RRR-alpha-tocopherol and graded levels of RRR-gamma-tocopherol over a 60 day period. Feeding rats with a RRR-alpha-tocopherol-supplemented diet induced in forebrain, sciatic endoneurium, skeletal muscle, heart and liver a marked increase in alpha-tocopherol concentration. In contrast, feeding rats with a diet containing the same level of RRR-gamma-tocopherol induced a small increase in gamma-tocopherol concentrations in brain, sciatic endoneurium, skeletal, muscle, heart and liver and a slight but significant decrease in alpha-tocopherol concentration in all tissues examined. In rats fed diets containing a constant level of RRR-alpha-tocopherol and graded levels of RRR-gamma-tocopherol, the concentrations of alpha-tocopherol in all tissues were much higher than those in rats fed a control diet containing RRR-alpha-tocopherol alone. The higher the gamma/alpha ratio, the more the alpha-tocopherol concentrations increased. Significant positive linear regressions were found between the gamma/alpha ratio and the alpha- and gamma-tocopherol concentrations in most of the tissues examined. These results indicate that when gamma-tocopherol was supplied continuously in the diet gamma-tocopherol accumulated significantly in the tissues but to a much smaller extent than when rats were fed with RRR-alpha-tocopherol. These experiments also indicate that gamma-tocopherol did not depress the serum and tissue alpha-tocopherol concentrations. On the contrary, gamma-tocopherol supplements induced a marked increase in alpha-tocopherol concentrations in the serum and tissues. These results suggest that there is a relationship between alpha- and gamma-tocopherol levels in vivo and that the biopotency of alpha-tocopherol should be reevaluated especially when high levels of gamma-tocopherol were present in the diet.

Animals↗
PubMed1997

Nitric oxide produced by ultraviolet-irradiated keratinocytes stimulates melanogenesis.

Ultraviolet (UV) radiation is the main physiological stimulus for human skin pigmentation. Within the epidermal-melanin unit, melanocytes synthesize and transfer melanin to the surrounding keratinocytes. Keratinocytes produce paracrine factors that affect melanocyte proliferation, dendricity, and melanin synthesis. In this report, we show that normal human keratinocytes secrete nitric oxide (NO) in response to UVA and UVB radiation, and we demonstrate that the constitutive isoform of keratinocyte NO synthase is involved in this process. Next, we investigate the melanogenic effect of NO produced by keratinocytes in response to UV radiation using melanocyte and keratinocyte cocultures. Conditioned media from UV-exposed keratinocytes stimulate tyrosinase activity of melanocytes. This effect is reversed by NO scavengers, suggesting an important role for NO in UV-induced melanogenesis. Moreover, melanocytes respond to NO-donors by decreased growth, enhanced dendricity, and melanogenesis. The rise in melanogenesis induced by NO-generating compounds is associated with an increased amount of both tyrosinase and tyrosinase-related protein 1. These observations suggest that NO plays an important role in the paracrine mediation of UV-induced melanogenesis.

Cell Division↗