Search PubMed⌕ Search

Biomedical subjects

A M Dupuy

Publications and source records attributed to A M Dupuy.

At least 19 recordsLinked to original sources
PubMed2006

Renal transplantation decreases osteoprotegerin levels.

Vascular calcifications are an important risk factor for cardiovascular mortality and morbidity in patients with chronic renal failure. Osteoprotegerin, a soluble decoy receptor for receptor activator NFkB ligand, has emerged as an independent predictive factor of atherosclerosis and vascular calcification in hemodialysis patients. Sparse data are available on the evolution of osteoprotegerin after renal transplantation. The aim of this study was to follow the evolution of serum osteoprotegerin levels and biochemical risk factors after renal transplantation. Forty patients were included. Blood samples for analysis were collected before and 3 months after renal transplantation. Besides the expected diminution in calcium-phosphate product, we have shown an early normalization of osteoprotegerin (10.05 +/- 4.77 pmol/L to 4.59 +/- 2.26 pmol/L). This study demonstrates that kidney transplantation improves this risk factor for vascular calcifications. However, these preliminary results should be confirmed and extended by the follow-up of vascular calcifications in the long term.

Adult↗
PubMed2006

Evaluation of an immunoassay (Abbott-IMX Analyzer) allowing routine determination of sirolimus: comparison with LC-MS method.

BACKGROUND: The use of the immunosuppressive agent sirolimus is increasing in renal transplantation but its monitoring often requires high-performance liquid chromatography (HPLC) with ultra-violet (UV) or tandem mass spectrometric (MS-MS) detection. The aim of this study was to compare a new microparticle enzyme immunoassay (MEIA, Microparticle Enzyme Immunoassay) on IMx Abbott Analyser with a liquid chromatography-mass spectometry (LC-MS) method. METHOD: The accuracy of immunoassay analytical performance including within run and between run imprecision and linearity was tested. For comparison studies, sirolimus level was then determined with the two methods on 98 samples from 52 transplant patients. RESULTS: Total intra-assay and inter-assay variation coefficients were below 10% at the three levels tested, and the coefficient of linearity was r = 0.99. The values obtained were highly correlated with the LC-MS method (MEIA = 1.02LC-MS + 0.91; r(2) = 0.87). As a result, the immunoassay showed good performance, and clinical sample measurements were not affected by the method. The MEIA may be a useful alternative for routine monitoring of sirolimus.

Chromatography, High Pressure Liquid↗
PubMed2006

Small dense low-density lipoprotein in renal transplant recipients: a potential target for prevention of cardiovascular complications?

BACKGROUND: Immunosuppressive therapy is frequently associated with dyslipidemia, which is involved in cardiovascular morbidity and mortality in transplant patients. Beyond classical factors, such as low-density lipoprotein (LDL) cholesterol (LDL-C), qualitative abnormalities of lipoproteins, such as presence of the atherogenic factor, small dense LDL, may be of interest for a cardiovascular risk assessment. This study was designed to explore LDL size in renal transplant recipients in relation to quantitative lipid parameters and apolipoprotein (apo) CIII polymorphism. METHODS: Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), LDL-C, apoA1, apoB, apoCIII, and LDL size were measured in 62 patients of mean age 45 +/- 13 years including 71% men at 2 +/- 0.5 years after renal transplantation. Thirty-two patients received cyclosporine (CsA), while 30 received tacrolimus (FK). ApoCIII Sstl genotype was determined by restriction fragment length polymorphism. RESULTS: The CsA group exhibited higher TC (P = .001), LDL-C (P = .004), non-HDL-C (P = .009), HDL-C (P = .03), apoB (P = .008), and apoCIII (P = .002) levels than the FK group. However, LDL-C (CsA: 3.7 +/- 1.2, FK: 3.0 +/- 0.6 mmol/L) and triglyceride levels (CsA: 1.55 mmol/L, FK: 1.37 mmol/L) were near the normal range in both groups. Allelic frequency of the sparse A2 allele associated with hypertriglyceridemia was 6%, similar to the general population. LDL size, which was comparable in the CsA and FK groups (25.87 +/- 0.89 vs 25.75 +/- 0.62 nm, respectively), inversely correlated with TG/HDL ratio (P = 10(-4)). Prevalence of small dense LDL (defined as <25.5 nm) was 26% in the CsA group and 33% in the FK group. CONCLUSION: After LDL-C goal has been achieved, LDL size modulation may be taken into account in order to prevent cardiovascular complications.

Adult↗
PubMed2006

The intensity level of physical exercise and the bone metabolism response.

This study investigated the short-term effects of the intensity level of physical exercise on bone metabolism and related hormones. The responses of calciotropic hormones and bone biochemical markers were evaluated in seven male cyclists (mean age 24.4 years, range 20-39) during two 50-min cycling tests performed 15% below (-VT) and 15% above (+VT) the ventilatory threshold. In each test, venous blood samples were drawn at rest, at the 30th and 50th min of exercise, and after 15 min of recovery. For both intensity levels, no significant variation in calcium, 25-hydroxyvitamin D, 1.25-dihydroxyvitamin D, or cortisol level was observed. Intact parathyroid hormone (iPTH) level increased significantly after the last minute of the test (41%, p < 0.05) and peaked during the recovery (80%, p < 0.05) only in response to exercise performed at +VT. Serum phosphorus concentration rose during both tests, while albumin levels increased only at +VT. Concerning bone cell activity, osteocalcin, and type I-C telopeptide breakdown products transiently increased only in response to exercise performed at +VT (11% and 16.8%, respectively; p < 0.05). Bone alkaline phosphatase increased similarly for both intensity levels after 30 min (12%, p < 0.05) and 50 min (12% for -VT vs. 14% for +VT, p < 0.05). All markers of bone turnover returned to initial values during the recovery. In conclusion, a no-impact but intense and sustained exercise performed at +VT transiently stimulated bone turnover and iPTH secretion, suggesting the existence of a bone stimulation threshold. In addition to the well known effect of mechanical constraints, both the duration and intensity of exercise may induce changes in bone turnover.

Adult↗
PubMed2006

Evaluation of a capillary zone electrophoresis system versus a conventional agarose gel system for routine serum protein separation and monoclonal component typing.

Capillary zone electrophoresis of serum proteins is increasingly gaining impact in clinical laboratories. During 2003, we compared the fully automated capillary electrophoresis (CE) system from Beckman (Paragon CZE 2000) with the method agarose gel electrophoresis Sebia (Hydrasis-Hyris, AGE). This new study focused on the evaluation of analytical performance and a comparison including 115 fresh routine samples (group A) and a series of 97 frozen pathologic sera with suspicion of monoclonal protein (group B). Coefficients of variation (CVs %) for the five classical protein fractions have been reported to be consistenly < 9% in within-run and < 10% in between-run imprecision studies with the Paragon 2000 system. The results of the comparison study (group A) demonstrated a good correlation between the CE system and AGE, except for beta-globulin (r = 0.65). Among the 97 pathologic serum samples (group B), there were 90 in which we detected a monoclonal protein by immunofixation (IF) (immunosubtraction (IS) was not used). AGE and Paragon 2000 failed to detect 7 and 12 monoclonal proteins, respectively, leading to a concordance to 92% for AGE and 87% for Paragon 2000 for identifying electrophoretic abnormalities in this group. Beta-globulin abnormalities and M paraprotein were well detected with Paragon 2000. Only 81% (21 vs 26) of the gammopathies were immunotyped with IS by two readers blinded to the IF immunotype. The Paragon 2000 is a reliable alternative to conventional agarose gel electrophoresis combining the advantages of full automation (rapidity, ease of use and cost) with high analytical performance. Qualified interpretation of results requires an adaptation period which could further improve concordance between the methods. Recently, this CE system has been improved by the manufacturer (Beckman) concerning the migration buffer and detection of beta-globulin abnormalities.

Antibodies, Monoclonal↗
PubMed2005

Changes in osteoprotegerin/RANKL system, bone mineral density, and bone biochemicals markers in patients with recent spinal cord injury.

This study analyzed the temporal and regional variations in bone loss and explored bone cell activities via biochemical markers during an extended follow-up in patients with spinal cord injury (SCI). In parallel, the possible role of the osteoprotegerin (OPG)/RANKL system in disuse osteoporosis was investigated. Seven male patients with acute and complete SCI (31.3 +/- 9.5 years) and 12 able-bodied (AB) men (26.9 +/- 4.2 years) participated in the study. Measurements were performed 16, 24, 36, 48, and 71 weeks after injury. At week 16, marked calcium homeostasis disturbance and a concomitant increase in bone resorption markers were observed, reflecting an intense bone degradation process. Resorption activity decreased continuously with time. Contrasting with the great rise in the resorption markers, the bone formation markers showed little variation. During the period of investigation, a loss in bone mineral density (BMD) was demonstrated for the total body (-4.3%), pelvis (-15.7%) and lower limbs (-15.2%), whereas BMD did not change at the lumbar spine, upper limbs, or skull. At all stages, SCI patients had lower serum RANKL levels and higher serum OPG levels than did AB controls, but no significant variation with time was observed for either cytokine. These findings suggest that bone resorption persisted long after SCI and specifically affected BMD at sublesional sites. The marked modification of serum OPG/RANKL levels in SCI patients suggests that this system is affected, in disuse osteoporosis. However, the precise biologic role of the OPG/RANKL system in the bone tissue of SCI patients has yet to be determined.

Absorptiometry, Photon↗
PubMed2005

Immunonephelometric determination of fibrinogen on citrated or heparinized plasma: comparison with functional Clauss method.

BACKGROUND: Fibrinogen is routinely determined by functional assay on citrated plasma in the hematology department. However, immunoassay can be performed easily with nephelometric analyzer in the clinical chemistry laboratory allowing automatization. The aim of this study was first to compare the clotting von Clauss method (activity assay) with an immunonephelometric method (antigen assay) on the BN ProSpec (Dade Behring). Moreover, we evaluated the possibility of collecting blood samples on heparin to facilitate blood collection for clinicians and reduce required blood collection volumes for dosages. METHODS: In a first step of experiment, the accuracy of immunonephelometric analytical performance was tested on heparinized and citrated tubes. For comparison studies, fibrinogen activity was then determined on citrated tubes in the hematology department and antigen measurement was performed on both citrated and heparinized plasma from 130 consecutive patients. RESULTS: As a result, the immunonephelometric method shows reliable performance and clinical sample measurements are not affected by the method used, validating the use of heparinized plasma samples for fibrinogen antigen determination with Dade Behring reagents.

Blood Specimen Collection↗
PubMed2004

Determination of beta2-microglobulin in biological samples using an immunoenzymometric assay (chemiluminescence detection) or an immunoturbidimetric assay: comparison with a radioimmunoassay.

Monitoring beta2-microglobulin (beta2M) in biological fluids has gained considerable interest in pathologies such as haematologic malignancies, renal diseases, and chronic inflammatory diseases. Due to limitations of the RIA in the routine laboratory, we measure beta2M with non-isotopic methods. 189 patients suffering from myeloma (n=66), end stage renal failure (n=54) or inflammation (n=69) were included in this study. beta2M was determined in serum, urine and dialysate using an immunoenzymometric assay with chemiluminescence detection [Immulite Diagnostic Products Corporation (DPC), La Garenne Colombes, France] and an immunoturbidimetric assay (Olympus, Rungis, France). The data were compared with a radioimmunoassay (Immunotech, Marseille, France) taken as a reference. Using serum samples, the immunoenzymometric assay with chemiluminescence detection and the immunoturbidimetric assay have reliable analytical performances. Values obtained with serum samples are highly correlated with the radioimmunoassay (DPC/RIA r2=0.84; Olympus/RIA r2=0.94) whatever the type of pathology; however an over-estimation which could be related to cross reactivity with beta2M fragments was observed with the RIA method as suggested by crossover calibration and recovery studies. Values obtained with urinary samples (n=96) are closely related to those obtained with the RIA (DPC/RIA r2 = 0.98; Olympus/RIA: r2=0.99). Despite the low levels observed in dialysate (n=57) good correlations were observed between Olympus vs DPC (r2=0.85). By contrast, the two non-isotope methods are poorly related with the RIA method (DPC vs RIA r2=0.47 and Olympus vs RIA r2=0.54). In conclusion, the immunoenzymometric assay with chemiluminescence detection or the immunoturbidimetric assay could be used in the routine laboratory in order to determine beta2M in plasma, urine and dialysate.

Body Fluids↗
PubMed2003

Comparison between the enzymatic vitros assay for creatinine determination and three other methods adapted on the Olympus analyzer.

To evaluate the relationship between the enzymatic Vitros assay for creatinine determination and other methods, we determined creatinine concentration in 400 heparin samples. Plasma creatinine level was successively determined on the Vitros 750 analyzer (Johnson & Johnson Co., Rochester, NY) and on the Olympus AU2700 analyzer (Olympus France, Rungis, France), using three reagents in the same assay: Olympus-Jaffé and two enzymatic commercial kits-Crea Plus (Roche Diagnostics, Meylan, France) and Enzymatic Creatinine (Randox, Mauguio, France). Comparison of Jaffé and enzymatic measurements of plasma creatinine levels revealed a high correlation when considering all values ranged from 20-1000 micromol/l (r > 0.99). However, for values <60 micromol/l, enzymatic reagents provided best results. Enzymatic methodology is a better clinical choice for the accurate measurement of creatinine, especially for neonates, pediatrics, and hematology units. Because analytical performance and the costs of Randox creatinine were satisfactory for our laboratory, this method, adapted on the Olympus analyzer, was chosen for routine determination of creatinine levels. According to the Valtec protocol (8), no interferences such as hemolysis, lipemia, or bilirubin were detected for Enzymatic Creatinine Randox.

Autoanalysis↗
PubMed2003

Decrease in LDL size in HIV-positive adults before and after lopinavir/ritonavir-containing regimen: an index of atherogenicity?

BACKGROUND: Hypertriglyceridemia (HTG) is frequently observed during highly active antiretroviral therapy (HAART) including protease inhibitor. Apolipoprotein (apo) CIII could be involved in this HTG by inhibition of triglyceride (TG) hydrolysis, which leads to the occurrence of small dense low density lipoprotein (sdLDL), a recognized cardiovascular risk factor. OBJECTIVE: To characterize the influence of lopinavir/ritonavir-containing regimen on lipoprotein profile. DESIGN AND METHODS: 24 antiretroviral-experienced HIV infected adults (including 14 patients in therapeutic interruption of at least 2 months) and 14 HIV uninfected healthy controls were enrolled. Serum lipid parameters (total cholesterol (TC), HDL-C, LDL-C, TG, apoA1, apoB, apoCIII), lipoprotein composition and LDL size were determined before initiation of lopinavir/ritonavir-containing regimen, and at 1 and 3 months thereafter. RESULTS: At baseline an atherogenic lipid profile was evidenced, characterized by a moderate HTG associated to a smaller mean LDL size (25.16 vs 25.93 nm, P<0.001), an enrichment in TG of LDL (11.4 vs 6.0%, P<0.01) and a high prevalence of sdLDL (75 vs 7%, P<0.01) when compared to controls. After 1 month of lopinavir/ritonavir-containing regimen, a significant reduction of LDL size (24.81 vs 25.16 nm, P<0.05) and a significant increase in cholesterol total (5.53 vs 4.49 mmol/l, P<0.001), in TG (4.20 vs 2.01 mmol/l, P<0.001), in apoA1 (1.28 vs 1.11 g/l, P<0.001), in apoB (1.08 vs 0.94 g/l, P<0.01), in apoCIII (0.16 vs 0.10 g/l, P<0.001), in TG percentage in LDL (14.4 vs 11.4, P<0.05) and in TG percentage in HDL (10.2 vs 8.3, P<0.05) were observed. CONCLUSIONS: Advanced stage of HIV infection is associated with an atherogenic lipid profile including a high prevalence of sdLDL. Lopinavir/ritonavir-containing regimen accentuates the reduction of LDL size. Since fibrates decrease TG and increase LDL size, they appear as a logical option to manage HAART-induced HTG.

Adult↗
PubMed2003

[Is C-reactive protein a marker of inflammation?].

C-reactive protein (CRP) is the prototype of acute-phase protein which is secreted by the liver in response to a variety of inflammatory cytokines. Levels of CRP can increase up to 1000-fold very rapidly after the onset of inflammation and decrease just as rapidly with the resolution of aggression. CRP is a member of the ancient highly conserved pentraxin family of proteins and it is arranged in a cyclic homopentameric structure. The important role of CRP in innate immunity is largely due to its opsonizing abilities, its capability to activate human complement and to bind to immunoglobulin G receptors. CRP can bind phosphocholine largely present in bacterial membranes, cell membrane and lipoproteins, in addition CRP can recognize nuclear constituent in damaged cells. CRP can activate C3 convertase through the classical pathway but not C5 convertase resulting in generation of opsonic complement fragments. Interactions of CRP with Fc receptors lead to the generation of proinflammatory cytokines and reactive oxygen species by monocyte/macrophage while inhibit neutrophiles functions. Recently, CRP was demonstrated to play an active role in atherogenesis and it has been largely proven that a microinflammatory state as defined by a moderate increase in CRP (up to 3 mg/l), is associated with an increased risk for arterial disease. Moreover it has been postulated that CRP may be a useful tool for monitoring drug therapy.

C-Reactive Protein↗
PubMed2001

Discrepancies between apolipoprotein E phenotyping and genotyping in the elderly.

We estimated the frequencies of phenotype (isoelectric focusing; IEF) vs. genotype (PCR/Hhal) discordance in a sample of an aged population (> 65 years). Both phenotype and genotype techniques have been used in the study of apolipoprotein E (apoE) polymorphism in 125 elderly subjects. The discordance between phenotype and genotype was unresolved in 11 (8.8%) of the 125 unrelated subjects studied. We observed a significant association between the presence of the E4 allele and both Alzheimer's disease (chi2 = 13, p < 0.001) and increased cholesterol concentration (Mann Whitney, p < 0.03). These relationships were not affected by the techniques used. Our results indicate that transcriptional modulation and post-transductional modifications in normal ageing and in aged-related diseases may explain in part discrepancies between gene analysis and protein characterisation.

Aged↗
PubMed1991

DNA restriction polymorphisms of the apolipoprotein AI-CIII-AIV gene cluster: a genetic determinant of atherosclerosis in type 2 (non-insulin-dependent) diabetes mellitus.

The presence of polymorphic restriction sites (S2, M2, P2) of the apolipoprotein AI-CIII-AIV gene cluster for the respective Sst1, Msp1, and Pst1 enzymes was assessed after hybridization with a radiolabelled apolipoprotein AI gene probe in 64 Type 2 diabetic patients and 67 healthy control subjects, all Europids. Twenty-two diabetic patients showed evidence of ischaemic heart disease or macrovascular arteriopathy and forty-two were free of cardiovascular complications. Control subjects were selected for the absence of personal or familial metabolic or cardiovascular diseases. The frequencies of polymorphic alleles were in agreement with previous studies in the control group: S2 6.3 (95% confidence interval (CI) 2.3-10.3) %, M2 5.5 (1.6-9.4) %, P2 6.3 (2.3-10.3) % and did not differ in the whole diabetic group: S2 4.2 (0.7-7.7) %, M2 6.5 (2.0-11.0) %, P2 6.6 (2.3-10.9) %. The relative prevalences of S2, M2, and P2 alleles were, respectively: 3.32, 1.54, and 2.00 (Woolf's ratio) in the macroangiopathic group but allele distribution frequencies were not statistically different from non-macroangiopathic patients. The allelic associations S2M2P1 and S1M1P2 showed a relative prevalence of 2.86 and 2.00 in the presence of cardiovascular complications but the difference was not significant in terms of polyallelic distribution frequencies in the absence of atherosclerosis. No serum lipid abnormalities could be related to the presence of any polymorphic allele or allelic association. These results suggest a genetic influence on the development of atherosclerosis in Type 2 diabetes, but the mechanism remains unclear.

Apolipoprotein A-I↗
PubMed1988

Antibody immobilization on swollen polystyrene tubes for the radioimmunological determination of total human serum IgE.

A new technique for preparing activated polystyrene tubes was developed involving the controlled swelling of plastic. The quantity of antibodies immobilized on these tubes, and consequently the quantity of bound IgE, was considerably increased. Calibration curves were plotted and the determination of total IgE in 200 serum samples confirmed the expected increase in sensitivity compared to a standard method. The manufacturing procedure was simple and could easily be automated. Thus, swollen polystyrene tubes constitute an advantageous solid stage in the assay of total IgE, which can improve the sensitivity of various radioimmunological determinations.

Antibodies↗
PubMedDate not supplied

Preliminary evaluation of a new chemiluminescence assay (Liaison Cyclosporine; DiaSorin Laboratories) allowing both C0 and C2 cyclosporine levels determination: comparison with RIA method.

Cyclosporine (CsA) monitoring is generally assessed by trough concentration determinations (C0). Recently, the 2-hour postdose CsA level (C2) has been proposed to be a better measurement to predict graft outcome and prevent toxicity. However, using the available methods, C2 determinations require external dilution, which impairs the precision and practicability of the assay. This study assessed the performance characteristics of a new competitive chemiluminescence immunoassay (CLIA, DiaSorin Laboratories, Anthony, France) for the determination of both C0 and C2 CsA concentrations in whole blood on a Liaison analyzer. The results were compared with the RIA method (DiaSorin) used in our laboratory as a reference technique. Analytical performances showed that the total intra-assay variation coefficients (CVs) on the CLIA Liaison ranged from 7.6% to 11.3%, while the between-day imprecision was 11% (15.2%, 11.5%, and 6.5%). The linearity of the method was estimated over the range of 30 to 2400 ng/mL as a correlation coefficient of r = .997. Recoveries, which were checked by adding pure CsA to CsA-free blood, showed a mean value of 86%. A total of 236 whole-blood samples (31% women, 69% men of mean age 45 +/- 17 years) were subjected to a comparative study of CLIA-CsA versus RIA (radioimmunoassay) values, yielding a correlation coefficient >0.90 (CLIA = 0.825RIA+21.611; r(2) > .90). In conclusion, the CLIA Liaison CsA kit represents an alternative to the radioisotopic method, which allows both C0 and C2 determinations without any preanalytical step. The chemiluminescence method demonstrated good analytical performance and practicability in routine use.

Adult↗