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Biomedical subjects

Philippe Arnaud

Publications and source records attributed to Philippe Arnaud.

32 records · Page 2Linked to original sources
PubMed2003

One step purification of alpha(1)-acid glycoprotein from human plasma. Fractionation of its polymorphic allele products.

Alpha(1)-acid glycoprotein is a plasma protein that exhibits both microheterogeneity and polymorphism. Its purification from human plasma is usually performed using a sequence of different fractionation steps. Here we report a one-step isolation technique of this protein based upon pseudo-ligand affinity chromatography on immobilized Cibacron Blue F3GA at acidic pH. In addition, the use of two narrow pH elution buffers allows us to separate the two genetic products of this protein, which differ from each other by 21 amino acid substitutions. This technique will facilitate the study of the structural, biological and pharmacokinetic properties of each individual allele product.

Alleles↗
PubMed2003

Theoretical study of the interaction between a high-valent manganese porphyrin oxyl-(hydroxo)-Mn(IV)-TMPyP and double-stranded DNA.

Cationic porphyrin derivatives such as meso-tetrakis(4-N-methylpyridinium)porphyrin, TMPyP, have been shown to interact with double-stranded DNA. The manganese derivative, Mn(III)-TMPyP, activated by an oxygen donor like potassium monopersulfate, provides an efficient DNA-cleaving system. Previous experimental work1 has shown that DNA cleavage by the Mn(III)-TMPyP/KHSO(5) system was due to an oxidative attack, within the minor groove of B-DNA, at the C5' or C1' carbons of deoxyribose units. The aim of this study was to use molecular modeling to elucidate the specificity of the interactions between the transient active species oxyl-Mn(IV)-TMPyP and the DNA target. Geometric parameters, charges, and force field constants consistent with the AMBER 98 force field were calculated by DFT methods. Molecular modeling (mechanics and dynamic simulations) were performed for oxyl-(hydroxo)-Mn(IV)-TMPyP bound in the minor groove of the dodecamer d(5'-TCGTCAAACCGC)-d(5'-GCGGTTTGACGA). Geometry, interactions, and binding energy of the metalloporphyrin located at the A.T triplet region of the dodecamer were analyzed. These studies show no significant structural change of the DNA structure upon ligand binding. Mobility of the metalloporphyrin in the minor groove was restrained by the formation of a hydrogen bond between the hydroxo ligand trans to the metal-oxyl and a DNA phosphate, restricting the access of the oxyl group to the (pro-S) H atom at C5'.

Base Sequence↗
PubMed2003

Imprinted methylation profiles for proximal mouse chromosomes 11 and 7 as revealed by methylation-sensitive representational difference analysis.

Proximal mouse Chromosome (Chr) 11 shares regions of orthology with the candidate gene region for the imprinting growth disorder Silver-Russell syndrome (SRS) on human Chr 7p. It has previously been shown that mice with two maternal or two paternal copies (duplications, Dp) of proximal Chr 11 exhibit reciprocal growth phenotypes. Those with two paternal copies show fetal and placental overgrowth, while those with two maternal copies are growth retarded. The growth retardation observed in the latter is reminiscent of the intrauterine growth restriction (IUGR) observed in SRS patients with maternal uniparental disomy for Chr 7 (mUPD7). We have carried out a methylation-sensitive representational difference analysis (Me-RDA) screen to look for regions of differential methylation (DMRs) associated with imprinted genes. For these experiments, we have used mouse embryos with uniparental duplications of Chrs 11 and 7 proximal to the breakpoint of the reciprocal translocation T(7;11)40Ad. Two previously known imprinted loci associated with paternal allele hypomethylation were recovered on proximal mouse Chr 11, U2af1-rs1 and Meg1/Grb10. These two genes map 15 cM apart, so it seems likely that they are within separate imprinted domains that do not contain additional DMRs. The known imprinted gene Peg3, located on mouse proximal Chr 7, was also detected in our screen. The finding that Peg3 was differentially methylated in embryos with uniparental inheritance of proximal Chr 7 confirms that Peg3 is located proximal to the breakpoint of T40Ad in G-band 7A2. Because GRB10 has previously been reported to be a candidate gene for SRS, we analysed 22 patients for epimutations of the GRB10 differentially methylated region that could lead to the altered expression of this gene. No such mutations were found.

Aneuploidy↗
PubMed2003

Cross-linking of hard gelatin carbamazepine capsules: effect of dissolution conditions on in vitro drug release.

The aim of this study was to determine if the use of both enzyme and surfactant in the dissolution medium changes the in vitro drug release from cross-linked hard gelatin capsules containing a water-insoluble drug. Hard gelatin capsules were cross-linked by a controlled exposure to formaldehyde resulting in different stressed capsules and carbamazepine (CBZ) was chosen as a drug model. In vitro dissolution studies were conducted using simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) with enzymes. Sodium lauryl sulfate (SLS) was added in the dissolution medium at a concentration of 2% m/v both in SGF and SIF with pepsin and pancreatin, respectively. The percentage of CBZ dissolved was reduced by increasing the degree of gelatin cross-linking. For unstressed hard gelatin capsules, 36% of the CBZ was released after 1 h, lowering to 5% for highly stressed hard gelatin capsules in the SGF. A similar effect was observed with SIF. In the case of moderately stressed hard gelatin capsules, addition of enzyme in the dissolution medium enhanced the percentage of CBZ dissolved. The dissolution level increased from 12% to 39% in SGF with pepsin for hard gelatin capsules cross-linked with 1500 ppm formaldehyde. On the contrary, the use of enzyme in the dissolution medium did not increase the dissolution of CBZ from highly stressed hard gelatin capsules. Surprisingly, the addition of SLS in the medium did not allow the release of the CBZ both in SGF and in SIF. The results of this study demonstrate that the use of enzyme in the dissolution medium is justified for moderately cross-linked hard gelatin capsules. However, the action of a surfactant added in the medium containing enzyme remains unclear.

Capsules↗
PubMed2003

Outcome in relation to treatment modalities in 48 patients with localized gastric MALT lymphoma: a retrospective study of patients treated during 1976-2001.

The aim of this study was to retrospectively analyze survival and tumor response data in patients with localized gastric MALT lymphoma treated by different treatment modalities other than anti-Helicobacter pylori treatment (diagnosis made before 1993, or after failure of antibiotics + anti-acid), including surgery, chemotherapy or combined treatment. Here we studied a series of 48 patients with stage IE or IIE disease treated during the past 11 years. These patients received different treatments: chemotherapy was proposed to 19 (40%) patients; gastric surgery to 21 (43%) patients, consisting of partial gastrectomy of 7 patients and total gastrectomy in 14 patients; combined treatment to 8 (17%) patients, consisting of surgery + chemotherapy in 7 patients and surgery + chemotherapy + radiotherapy in 1 patient. At diagnosis, 85% of the patients had good PS and no B symptoms. Complete response after treatment was reached in 45 (94%) patients (chemotherapy: 84% of the patients; surgery alone: 95%; combined treatment: 100%). Progression was observed in 16 (33%) patients. No statistical difference in the survival was found among the different therapeutic modalities: 5-year overall survival year FFP survival was 81% for chemotherapy, 86% for surgery alone and 95% for combined treatment. Prognostic factors for survival were age, performance status and hemoglobin level at diagnosis. Considering the natural bias of a retrospective analysis, surgery or chemotherapy was associated with a similar outcome in patients with MALT lymphoma after antibiotics failure.

Adult↗
PubMed2003

Epigenetic properties and identification of an imprint mark in the Nesp-Gnasxl domain of the mouse Gnas imprinted locus.

The Gnas locus in the mouse is imprinted with a complex arrangement of alternative transcripts defined by promoters with different patterns of monoallelic expression. The Gnas transcript is subject to tissue-specific imprinted expression, Nesp is expressed only from the maternal allele, and Gnasxl is expressed only from the paternal allele. The mechanisms controlling these expression patterns are not known. To identify potential imprinting regulatory regions, particularly for the reciprocally expressed Nesp and Gnasxl promoters, we examined epigenetic properties of the locus in gametes, embryonic stem cells, and fetal and adult tissues. The Nesp and Gnasxl promoter regions are contained in extensive CpG islands with methylation of the paternal allele at Nesp and the maternal allele at Gnasxl. Parental allele-specific DNase I-hypersensitive sites were found at these regions, which correlate with hypomethylation rather than actual expression status. A germ line methylation mark was identified covering the promoters for Gnasxl and the antisense transcript Nespas. Prominent DNase I-hypersensitive sites present on paternal alleles in embryonic stem cells are contained within this mark. This is the second gametic mark identified at Gnas and suggests that the Nesp and Gnasxl promoters are under separate control from the Gnas promoter. We propose models to account for the regulation of imprinting at the locus.

Alleles↗
PubMed2002

The mouse Zac1 locus: basis for imprinting and comparison with human ZAC.

We identified a maternally methylated CpG island at the mouse Zac1 locus on chromosome (Chr.) 10 in a screen for imprinted genes. The homologous human gene ZAC (also known as LOT1 and PLAGLI) is a candidate gene for transient neonatal diabetes (TNDM), an imprinted disorder associated with paternal duplication for 6q24 and characterized by intrauterine growth retardation and insulin dependence. A mouse model would be indispensable to investigate the basis of the disorder, however, there is apparently no similar phenotype in mice with the corresponding chromosome anomaly. To begin to understand this difference, we have undertaken a comparative analysis of the mouse and human genes. We show that the CpG island is far upstream of the coding body of mouse Zac1, that Zac1 transcripts initiate in a conserved region in the CpG island, and transcripts undergo complex splicing--all properties shared with the human gene. CpG island methylation is present in oocyte DNA and constitutes a germline-specific epigenetic mark. Mice with uniparental disomy (UPD) for Chr. 10 exhibit appropriate parent-of-origin dependent expression of Zac1, indicating that the absence of phenotypes comparable to aspects of human TNDM is not because imprinting of Zac1 is relaxed in these UPD mice.

5' Flanking Region↗
PubMed2002

Cloning of the IgM heavy chain of the bottlenose dolphin (Tursiops truncatus), and initial analysis of VH gene usage.

Clones encoding the dolphin IgM heavy (micro) chain gene were isolated from a cDNA library of peripheral blood leukocytes. Genomic Southern blot analyses showed that the dolphin IGHM gene is most likely present in a single copy, and its sequence shows greatest similarity to those of the IGHM gene of the sheep, pig and cow, evolutionarily related artiodactyls. The transmembrane (TM) form of the IGHM chain was isolated by 3' RACE. While showing similarities to the TM regions of other mammalian IGHM chains, the highly conserved Ser residue of the CART motif is substituted with a Gly in the dolphin. In contrast to the pig and cow, which utilize only a single VH family, the dolphin expresses at least two distinct VH families, belonging to the mammalian VH clans I and III. At least two JH genes were identified in the dolphin. Some CDR3 regions of the dolphin VH are long (up to 21 amino acids), and contain multiple Cys residues, hypothesized to stabilize the CDR3 structure through disulfide bond formation.

Amino Acid Sequence↗
PubMed2002

Human fetuin/alpha2HS-glycoprotein level as a novel indicator of liver cell function and short-term mortality in patients with liver cirrhosis and liver cancer.

OBJECTIVE: Human fetuin/alpha2HS-glycoprotein (AHSG) is synthesized by hepatocytes. We intended to determine whether liver dysfunction or acute phase reaction is dominant in the regulation of its serum concentrations and to see if decreased AHGS levels are associated with short-term mortality. DESIGN: We determined the serum AHSG levels in patients with acute alcoholic, acute A, B, and Epstein-Barr virus hepatitis, alcoholic cirrhosis, and hepatocellular cancer and correlated them to conventional laboratory parameters of inflammation and liver function. Patients were followed for 1 month. METHODS: Serum AHSG was determined by radial immunodiffusion. RESULTS: Compared to controls, significantly lower AHSG levels were found in patients with liver cirrhosis and hepatocellular cancer but not the acute viral hepatitides. Strong positive correlation with serum transferrin, albumin and prothrombin was found. Febrile episodes were not associated with significantly decreased AHSG levels. Concentrations below 300 microg/ml were associated with high mortality rate (52.0%; relative risk, 5.497; 95% confidence interval, 2.472-12.23; P < 0.0001). Of all laboratory parameters studied serum AHSG levels showed the greatest difference between deceased and survived patients with cirrhosis and cancer. Moreover, other acute phase reactants did not differ significantly. The multiple logistic regression analysis indicated that the decrease of serum AHSG is independent of all other variables that were found decreased in deceased patients. CONCLUSIONS: Decreased serum AHSG concentration is due rather to hepatocellular dysfunction than the acute phase reaction and is an outstanding predictor of short-term mortality in patients with liver cirrhosis and liver cancer.

Acute-Phase Reaction↗
PubMed2002

Evaluation of the cytotoxicity effect of dimethyl sulfoxide (DMSO) on Caco2/TC7 colon tumor cell cultures.

Dimethyl sulfoxide (DMSO) is usually used to solubilize poorly soluble drugs in permeation assays such as that using Caco2 enterocyte-like cells. The objective of this study was to evaluate the toxicity of DMSO on Caco2/TC7 cells and determinate the maximal concentration usable in permeation experiments. Caco2/TC7 cells were cultured for 21 d on 96-well plates for evaluation of toxicity. The determination of lactate dehydrogenase (LDH) release in cell supernatant and the measurement of Neutral Red (NR) uptake are used for cytotoxicity assays. DMSO solutions (0-100%) in Hank's balanced salt solution containing HEPES (25 mM), pH 7.4, were incubated with Caco-2/TC7 cells on 96 well plates. Caco2/TC7 cells were cultured on Transwell-Clear inserts to evaluate the influence of DMSO on the apparent permeability of the paracellular marker mannitol. DMSO 10% did not induce any significant increase in LDH release whereas a significant increase in LDH activity (ANOVA, p<0.05) occurred at a DMSO concentration of 20 to 50%. NR incorporation in viable cells was statistically reduced by 27 to 36% at DMSO concentration of 20% up to 100% (ANOVA, p>0.05). No statistical difference (p<0.05) in apparent mannitol permeability was observed between the control and 10% DMSO groups. In conclusion, at concentrations of up to 10%, DMSO did not produce any significant alteration in apical membrane permeability or on cell-to-cell tight junctional complexes.

Biological Transport↗
PubMed2002

Treatment of splenic marginal zone B-cell lymphoma: an analysis of 81 patients.

Splenic marginal zone B-cell lymphoma (MZL), with or without villous lymphocytes, is an indolent lymphoma, presenting with massive splenomegaly, generally associated with bone marrow dissemination. In patients requiring therapy, splenectomy has been reported as the treatment of choice. We reviewed the cases of 81 patients with splenic MZL. Patients presented with stage IV disease at diagnosis in 95% of the cases. Autoimmune events (hemolytic anemia, immune thrombocytopenia, acquired coagulation disorders, positive Coomb's test) were observed in 16 patients, and a monoclonal (M) serum component was detected in 46% of the patients. Twenty patients did not receive any initial treatment at diagnosis. Splenectomy was proposed in 79% of the treated patients, with adjuvant chemotherapy in 47% of patients. Median survival was 10.5 years and was significantly shorter in the presence of an M component, an elevated b2-microglobulin level, leukocyte count > 20000/microL, and lymphocytes > 9000/microL. Disease progression was significantly more frequent in patients presenting an immunological event or an M component. Seventy percent of the patients had persistent involvement of bone marrow and/or peripheral blood after splenectomy. Disease progression was significantly more frequent in partial responders than in complete responders (P < 0.005), but overall survival, risk of histologic transformation, and risk of death from lymphoma were not different in the 2 groups. Moreover, patients with cytopenia at diagnosis treated by splenectomy alone rapidly recovered normal hematological parameters. We conclude that splenectomy is an efficient treatment for splenic MZL, but that it may be delayed until the occurrence of symptoms or cytopenia.

Adult↗
PubMedDate not supplied

Alpha2-HS glycoprotein: a protein in search of a function.

In this issue (pp. 305-310) Jun Ren and Amy J. Davidoff author an article entitled 'Alpha2-HS glycoprotein, a putative inhibitor of tyrosine kinase, prevents glucose toxicity associated with cardiomyocyte dysfunction'. The protein responsible for this biological activity has recently come to the forefront of research on the biological activity of plasma proteins.

Animals↗
PubMedDate not supplied

[Pharmacologic criteria for medical substitution in opiate dependence].

Our goal was to establish new pharmacological criteria for a drug to be used in the treatment of opioid dependence. We propose the following six pharmacodynamic and pharmacokinetic criteria: (i) the same pharmacodynamic properties as the drug being substituted; (ii) a long duration of action (minimum 24 hours, not requiring several daily doses) in order to prevent fluctuations in effect and especially withdrawal symptoms; (iii) few euphoric effects together with a minimal reinforcing effect for the drug itself and other drugs; (iv) oral or sublingual administration without any special affinity for other routes, especially the intravenous; (v) a New Drug Application (NDA) in this indication, after submission of a dossier including both clinical randomised comparative trials and security data; and (vi) compatibility with a socially satisfying quality of life. These criteria were applied to methadone, buprenorphine and other drugs that were proposed in the treatment of opioid dependence (such as morphine or codeine).

Codeine↗