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Biomedical subjects

A Gauthier

Publications and source records attributed to A Gauthier.

At least 73 records · Page 4Linked to original sources
PubMed1995

Influence of hydroxypyridones and desferrioxamine on the mobilization of aluminium from tissues of aluminium-loaded rats.

Significantly increased levels of aluminium were assayed in the liver and various brain regions of male Wistar rats after intra-peritoneal injection of aluminium gluconate for a period of 1-2 months. Cessation of aluminium gluconate administration for one month did not alter the tissue content of aluminium, apart from the spleen and hippocampus, indicating temporal stability of the aluminium loading. Administration of desferrioxamine, or one of the hydroxypyridone chelators, decreased tissue aluminium content in the liver and in all regions of the brain investigated. Desferrioxamine was more effective in mobilizing liver aluminium than either of the two hydroxypyridones, CP20 and CP94, whereas the more hydrophobic of the hydroxypyridones, diethyl hydroxypyrid-4-ones, (CP94), was most effective in mobilizing brain aluminium. From the present study it appears that orally active chelators of appropriate hydrophobicity may be extremely effective in mobilizing brain aluminium.

Aluminum↗
PubMed1995

Bile salt secretion by hepatocytes incubated with bile salts and liposomes or low density lipoproteins.

The purpose of this work was to determine the effect of exogenous unesterified cholesterol provided in either artificial liposomes or LDL on bile salt synthesis by isolated rat hepatocytes. Rates of de novo synthesis were determined in the presence of 300 or 600 microM taurocholate, 600 microM taurodehydrocholate, cholate, deoxycholate or chenodeoxycholate. There was no significant difference between the cholesterol uptake by hepatocytes when the degree of hydrophobicity of the bile salts changed (cholate vs deoxycholate or chenodeoxycholate). Compared to taurocholate, taurodehydrocholate lowered the hepatic incorporation of unesterified cholesterol for the first 60 minutes; compared to control, taurocholate stimulated the cholesterol incorporation for the first 20 minutes. A possible explanation for this finding would be an interaction between bile salts and exogenous cholesterol, depending on the kind of conjugated bile salt. Taurocholate increased the exchange of cholesterol between liposomes or LDL and hepatocyte membranes. It resulted in a significant increase of bile salt synthesis and secretion. This phenomenon was not observed with taurodehydrocholate.

Animals↗
PubMed1995

HLA class II gene polymorphism in Tunisians.

The polymorphism of HLA class II genes (HLA-DRB, DQB, DPB) was investigated in 101 Tunisians using polymerase chain reaction. (PCR) amplification and reverse dot blot (RDB) hybridization. Allele and haplotype frequencies, as well as DRB1-DQB1 linkage disequilibria, were calculated. A total of 26 DRB1 alleles were detected and the most prevalent variant was DRB1*0301 with an allelic frequency at 21.87%. In the DR1 group, DRB1*0102 was most frequent than DRB1*0101. In the DR4 group, DRB1*0403 was the most common allele and was associated with DQB1*0402. Interestingly this DRB1-DQB1 association has not been observed in other populations. With regard to the DR8 group, DRB1*0804 was the unique variant detected, whereas with the DR13 specificity, the most common variant was DRB1*1303 in Algerians also. Although the DQB1 polymorphism analysis showed an allelic distribution very close to that observed in caucasoids, many DRB1-DQB1 associations which have not been reported in studies of other populations, were described. Finally at the DPB1 locus DPB1*1701 and *1301 allele frequencies distinguish clearly this Tunisian sample from a French caucasoïd panel of 83 subjects. In conclusion, a specific distribution of HLA components in terms of gene and haplotype frequencies characterizises this Tunisian population. This specific pattern may reflect the great ethnic diversity of this community. All these informations may be helpful in the future for HLA and disease association studies.

Gene Frequency↗
PubMed1995

[Treatment of caustic stenoses of the upper digestive tract].

Stenosis of the upper digestive tract developed in 22 patients with stage IIB or stage III caustic burns due to massive ingestion of an alkaline substance in 18 cases and an acid substance in 4 cases is analysed. Emergency oesogastrectomy without thoracotomy was performed in emergency situations in 10 patients in whom mortality reached 30%. For the remaining 12 patients with minimal stage IIB lesions, a jejunostomy was opened for enteral nutrition. After three months, stenosis developed in 10 cases and required surgical treatment in 7 after failure of endoscopic dilatations. Surgery included retrosternal coloplasy with oesophagectomy for 3 patients. There were no deaths. Two patients with a stenosis of the cervical anastomosis were treated endoscopically. These results suggest that the use of the endoscope in the acute phase can help ascertain the best management technique and confirms that stage IIB stenosis can develop a tight stenosis in 50% of the cases. This situation requires surgical treatment in 70% of the cases.

Adult↗
PubMed1994

Abnormal expression of protein 4.1 in spermatozoa of infertile men with teratospermia.

Molecular defects responsible for morphologically abnormal spermatozoa (teratospermia) associated with male sterility are largely unknown. We report defective expression of protein 4.1, a cytoskeletal protein initially recognised in red cells. In some patients with severely amorphous sperm heads, protein 4.1 had an abnormal sub-cellular localisation (tail instead of head) and appeared as high-molecular-weight isoforms, especially a 135 kDa species instead of the 82 kDa isoform seen in fertile sperm. Because the 135 kDa isoform is characteristic of immature germ cells from testis, its presence in teratospermia suggests profoundly disturbed sperm differentiation.

Cytoskeletal Proteins↗
PubMed1994

Ultrastructural changes in brain parenchyma during normal aging and in animal models of aging.

During aging, the brain parenchyma of animals and humans share many similarities, both in the gray and the white matter. Unfortunately, until now, neither aged animals nor animal models reproduce the two hallmarks of aging of the human brain: senile plaques and tangles. Therefore, observations performed on animals are limited to some aspects of the involutive process which affects brain parenchyma during aging and their appropriateness to the human situation. One striking aspect concerns the occurrence of vacuolated necrotic cells whose number increases with advancing age. These cells can constitute markers of the brain involutive process and they characterize, both in animal and human, the more vulnerable areas of the brain affected by the neuronal rarefaction. Experimental animal models can be used to study the various conditions which sustain the cell survival and to determine, at the cellular level, the factors leading the brain parenchyma to an irreversible state of degradation.

Adult↗
PubMed1994

Pharmacokinetics of a single oral dose of clobazam in patients with liver disease.

The pharmacokinetic effect of a single oral in dose of 20 mg clobazam was studied in 15 patients with liver disease and in 6 healthy volunteers. Plasma concentrations of clobazam and its main metabolite, norclobazam, were measured by gas liquid chromatography. Clobazam was rapidly absorbed. Peak plasma concentrations were 350 +/- 63 ng/ml at 1.7 +/- 0.8 hr in healthy volunteers, 239 +/- 70 ng/ml at 3 +/- 1.9 hr in patients with viral hepatitis and 240 +/- 113 ng/ml at 2.5 +/- 1.5 hr in patients with cirrhosis. Total distribution volume was 173 +/- 88 l and 168 +/- 71 l in patients with viral hepatitis and cirrhosis respectively, and 81 +/- 20 l in volunteers. Corresponding half-life values were 47 +/- 18 hr and 51 +/- 21 hr in patients and 22 +/- 6.3 hr in volunteers. The difference between patients was not significant, whereas the difference between patients and volunteers was significant.

Absorption↗
PubMed1994

An experimental animal model of aluminium overload.

In order that better therapeutic approaches to disorders in man characterized by aluminium (Al) overload might be developed it is essential to have an appropriate animal model. Chronic oral administration of Al citrate to male Wistar rats leads to an Al overload in a relatively short period of time when compared to previous published animal models. Liver and brain Al levels are increased by 25 and 30-fold respectively compared to control rats after 6 months of loading. Al tissue content was significantly greater when the Al citrate was administered in an iron-free diet. The distribution of Al in brain was similar to that in the Al encephalopathy of patients with chronic renal failure or Alzheimer's disease and is in accord with observations that areas of brain that accumulate greatest amounts of Al have highest concentrations of transferrin receptors. In the brain, the toxic effect of Al at the cellular level was characterized by an extensive cytoplasmic vacuolation in astrocytes (especially) and neurones. These changes are reminiscent of those observed in certain human neurodegenerative diseases.

Administration, Oral↗
PubMed1993

[Chronic hepatitis C and Gougerot-Sjogren syndrome. Apropos of a case].

The authors report a patient with concomitant Sjögren's syndrome and chronic hepatitis C. Close associations between autoimmune liver disease, chronic hepatitis C, and Sjögren's syndrome have been demonstrated. The most likely hypothesis involves triggering of an autoimmune cascade by the hepatitis C virus. Prevalence of hepatitis C virus infection in patients with Sjögren's syndrome and potential therapeutic implications of this disease combinations remain to be determined.

Autoimmune Diseases↗
PubMed1992

Effects of cyclosporine and corticosteroids on bile secretion in the rat.

In order to study their effects on the bile secretion, cyclosporine and methylprednisolone were injected intravenously into rats at a dose of 10 mg/kg b.w. for 30 min. Methylprednisolone had no effect on bile secretion. Cyclosporine led to transient intrahepatic cholestasis characterized by decreased bile flow as well as a decrease of bile salts and cholesterol in bile. Phospholipid levels were not affected. Liver biopsy showed no particular anomaly. These findings suggest that the observed cholestatic reaction may be due to impairment of the metabolism of cholesterol into bile salts or of the conjugation of bile salts rather than to disturbances in bile secretion. After liver transplantation in humans, cholestasis associated with acute rejection or nonspecific cholestasis cannot be attributed directly to the effect of cyclosporine. Cholestasis can be offset by administering taurocholate at a dose of 10 mumol/min/kg b.w. in order to maintain bile salt and phospholipid levels high enough to ensure proper "vectorization" of cholesterol to bile.

Animals↗
PubMed1992

Clinical evaluation of a new triphasic oral contraceptive: norgestimate and ethinyl estradiol.

The safety and efficacy of the triphasic oral contraceptive agent containing norgestimate and ethinyl estradiol were evaluated in a 12-month study of 661 women. Excellent contraceptive efficacy was achieved, with two pregnancies ascribed to product failure in a total of 6,511 treatment cycles. The life-table predicted pregnancy rate was 0.57 per 100 woman-years of use. The overall and theoretical Pearl indexes were 0.55 and 0.37, respectively. Good cycle control was maintained in patterns similar to those noted in previous studies. The incidence of dysmenorrhea and premenstrual syndrome was sharply reduced. Side effects reported were typical of those associated with use of low-dose oral contraceptive agents. Acceptability was high compared with agents used previously by the subjects. Total cholesterol did not change but high-density lipoprotein cholesterol was significantly elevated at 3 and 12 months. There were no clinically significant changes in the parameters of hematology or blood chemistry tested.

Adolescent↗
PubMed1991

A group I intron in the chloroplast large subunit rRNA gene of Chlamydomonas eugametos encodes a double-strand endonuclease that cleaves the homing site of this intron.

During interspecific crosses between Chlamydomonas eugametos and Chlamydomonas moewusii, an optional group I intron of 955 base pairs (CeLSU.5) in the C. eugametos chloroplast large subunit rRNA gene undergoes a duplicative transposition event which is associated with frequent co-conversion of flanking cpDNA sequences. In the present study, we show that the basic protein of 218 amino acids encoded by CeLSU.5 could mediate the phenomenon of intron transposition, also called intron homing. We overexpressed the ORF specifying this protein in E. coli using expression vectors that contain a C. moewusii cpDNA sequence encompassing the intron homing site. The expression product was found to exhibit a double-strand DNA endonuclease activity that is specific for the homing site. This activity was detected in vivo by self-linearization of the expression plasmids.

Amino Acid Sequence↗
PubMed1991

Transfected trophoblast-derived human cells can express a single HLA class I allelic product.

The human trophoblast-derived JAR cell line, that does not express polymorphic HLA class I antigens even after IFN induction, can be stably transfected by genomic clones encoding the entire HLA-A2, -A3 and -B7 alpha-chain genes. The transfected genes were expressed at the cell surface in association with endogenous beta 2-microglobulin (shown by FCM analysis) as a single allelic product without reexpression of any endogenous class I gene (shown by 1D.IEF analysis). Furthermore, TNF-alpha and IFN-gamma, alone and synergistically, increase cell surface expression of transfected MHC class I/endogenous beta 2m heterodimers without induction of endogenous class I alpha-chain genes. These data show that the MHC class I-negative JAR human cell line might be used for transfections with the aim of establishing human cells expressing just one defined MHC class I allele for functional and regulatory studies. These findings are discussed in relation to the methylated status solely of endogenous class I alpha-chain genes in JAR cells and suggest that transfected class I genes are not regulated in the same fashion and, in particular, that constitutive and TNF/IFN inducible trans-acting regulatory factors able to bind to cis-promoter/enhancer sequences of class I DNA are likely to be present.

Alleles↗