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I Beucler

Publications and source records attributed to I Beucler.

52 records · Page 3Linked to original sources
PubMed1983

[Structure and metabolism of plasma lipoproteins].

Blood plasma contains lipoproteins of which the structure and the composition are not constant during the time and that depend on their metabolic evolution from their synthesis rate in intestine or liver to their utilization in the liver or the peripheral tissues. The composition and the pathway of the different lipoprotein classes (chylomicrons, VLDL, LDL, HDL) are reviewed, as also the main pathological perturbations that attack them.

Chemical Phenomena↗
PubMed1982

Infantile phytanic acid storage disease, a possible variant of Refsum's disease: three cases, including ultrastructural studies of the liver.

Three cases of phytanic acid storage disease with symptoms during the first months of life are reported. Hepatomegaly, facial dysmorphia, growth and/or mental retardation and osteopenia were observed in addition to retinitis pigmentosa and neurosensory deafness. The presence of phytanic acid in serum (160-320 mumol/1 (50-100 micrograms/ml)) was accompanied by hypocholesterolaemia. Electron microscopy showed that a storage material had accumulated in mesenchymal and parenchymal liver cells. Lamellar structures were seen in hepatocytes and other storing cells. These inclusions resembled the structures found in plant chloroplasts containing phytol. Some of the clinical and biological data obtained were consistent with Refsum's disease. However, other characteristics such as mental retardation, hepatomegaly, osteopenia, hypocholesterolaemia and hypoalphalipoproteinaemia, as well as the ultrastructural findings in the liver, suggested that our patients' illness was either a phytanic acid storage disease different from the classical form of Refsum's disease, or a more severe early symptomatic form of Refsum's disease. Early diagnosis by phytanic acid assay and electron microscopic liver examination calls for prescription of a low phytanate diet in the hope of improving the child's condition.

Child↗
PubMed1982

[Immunological assay of apolipoprotein A-I].

Since lipid free apo A-I and lipid rich apo A-I (HDL, LP A, LP A-I) have different accessible antigenic sites, the electroimmunoassay ("rocket") does not allow the determination of the apo A-I concentration in both lipoproteins and serum when lipid free apo A-I are taken as controls. The results are found more significant when an isolated HDL or serum are used as reference. A comparison is made with the results (height of the pics) obtained for the same sample with different antibodies anti apo A-I, checked with the same HDL control, great differences two to one is observed. It is only explained by the various composition of antibodies directed against different apo A-I antigenic sites. Differences obtained in the levels of apo A-I in HDL2 and in HDL3 by immunoprecipitation show that the more lipoproteins are lipid rich the less their apo A-I are reached by antibodies.

Animals↗
PubMed1978

Abnormal lipoproteins in a case of primary biliary cirrhosis.

The serum of a patient diagnosed as a primary biliary cirrhosis was studied during the various evolutive stages of the disease. During the non-icteric period, the serum lipoprotein had the chemical composition (rich in cholesterol and phospholipids) of that found in cholestasis; however the bilirubinemia was normal, and no LPX was detected; there was a normal esterified to total cholesterol ratio and the alphaLP had not decreased, as expected, but increased and was divided into two fractions; immunoelectrophoretic studies of ultracentrifugal fractions showed some LP with HDL immunological properties, but with lower densities than that of normal HDL. We suggest that the phospholipid overloading of some of these HDL in the patient's serum could explain the changes in density. Some months after this study, the patient's serum exhibited the characteristics found in cholestasis, with disappearance of HDL and appearance of LPX. During the subsequent period, the serum again contained phospholipid rich HDL and LPX. In fact several LPX with different densities were found. It seems, therefore, that in cholestasis, LP undergo modification in which the HDL peptide chains play an important role.

Bilirubin↗
PubMed1977

[Apolipoprotein abnormalities in low and very low density lipoproteins in a type V hyperlipemia (author's transl)].

Abnormalities in VLDL and LDL apolipoproteins have been observed in the serum of an 11 year old girl with a type V hyperlipoproteinemia (VLDL + chylomicrons). This was shown with polyacrylamide gel electrophoresis and also with two dimensional immunoelectrophoresis. The LDL contain peptides which are not found in normal apo LDL. In the VLDL, heterogeneity of the lipopeptides is more marked that in normal VLDL, and there is an abnormal distribution of the apolipoproteins C or D.

Child↗
PubMed1976

[An immunoelectrophoretic study of plasma lipoproteins in a case of familial deficiency of lecithin-cholesterol acyltransferase (author's transl)].

The lipid composition and apopeptide patterns of plasma LDL and VLDL have been studied in a patient with LCAT deficiency, using two-dimensional immunoelectrophoresis. After absorption of a fat meal an elevation of VLDL apopeptides C was observed. Apo-LDL also showed an abnormal relative increase of apo-C. After heparin-induced lipolysis, a shift of apo-C from chylomicra and VLDL to LDL was noticed by the striking increase of apo-C in this last lipoprotein class. In view of the present and previously published results the possible mechanisms involved in lipoprotein catabolism in LCAT deficiency are discussed.

Acyltransferases↗
PubMed1976

[Immunologic study of human low density lipoproteins].

The human serum Low Density Lipoproteins (d : 1,020 - 1,055 g/ml) is composed of lipoproteins B and small amount components which can be precipited during an immunological reaction specifically with lipoproteins C antibodies. Moreover the ethyl-ether treatment induces a dissociation of the LDL into several subunits which have different immunological specificities.

Apolipoproteins↗
PubMed1975

[Two-dimensional immunoelectrophoresis of spontaneous dissociation of low density lipoproteins].

Plasma-lipoproteins isolated between d 1.020 and d 1.055 g/ml were partially delipidated with ethyl ether at 4 degrees C. This treatment induces a transformation of the lipoproteins which is evolutive during several days. Bidimensional immunoelectrophoresis reveals the lipoproteins dissociation and the appearance of 4 immunologically different fractions. The time dependent formation of these subunits is slowed down by EDTA and less efficiently by antioxydants. Once started, the dissociation can be accelerated by heating at 37 degrees C or by UV exposition. Another lipopeptide is more easily revealed by anti VLDL antiserum. It can be shown in the native and in the partially or completely delipidated LDL. Its presence does not depend on lipoprotein dissociation.

Humans↗
PubMedDate not supplied

[Familial hypobetalipoproteinemia. Familial study of 4 cases].

A familial study of four cases with hypobetalipoproteinemia is reported. Three members are heterozygous and one is homozygous. This congenital fat malabsorption in homozygous state is commonly associated with an absence of serum apoprotein B and LDL. Neuromuscular and ophthalmological signs are absent in this case. The major role of upper digestive endoscopy in the diagnostic procedure is emphasized. Histochemical and immunoenzymatic stains of enterocytes and intestinal organ culture show defective synthesis apo B in the homozygous patient. Studies of DNA polymorphism in the homozygous patient have shown that the apo B gene doesn't certain major insertions or deletions. These results are discussed.

Adult↗
PubMedDate not supplied

[Multicenter evaluation on different analyzers of three methods for direct HDL-cholesterol assay].

Most frequently, in routine laboratories, C-HDL is measured in the supernatant after precipitation of apolipoprotein B-containing lipoproteins by the sodium phosphotungstate/magnesium chloride reagent (PTA). This method involves precipitation, centrifugation and decantation steps which prevent full automation of the measurement and decrease the accuracy of the results. Recently, three direct assays for C-HDL including alpha-cyclodextrin sulphate (alpha-CD), polyanions/detergents (PA-D) or antibodies anti-beta-lipoproteins (AC) have been commercialized, in which all steps are fully managed by automated analyzers. These new methods have been compared to the conventional procedure (PTA), in multicenter studies among six laboratories using different analyzers. The C-HDL values measured by the alpha-CD and PA-D assays correlated well with those of the PTA method (r > 0.98), on most of the analyzers. With the AC assay, only the results obtained with the Hitachi 717 analyzer were correlated with C-HDL values of the PTA method. The linearity and specificity studies were evaluated in the laboratory A on a Kone Specific analyzer. The alpha-CD and PA-D assays were linear for C-HDL values from 0 to 5.56 mmol/l, as observed by increasing amounts of HDL2 + HDL3 or serum without lipoprotein isolated by ultracentrifugation. The specificity of these two methods was evaluated simultaneously, by adding various amounts of lipoproteins isolated by sequential ultracentrifugation. No interference was observed when adding chylomicrons up to 13.4 mmol/l of triglycerides for both methods. Inversely, increased C-HDL values were observed with added VLDL from 6 mmol/l of triglycerides for the PA-D assay and from 8 mmol/l for the alpha-CD assay. No interference was observed with added LDL up to 11.5 mmol/l of C-LDL for the alpha-CD assay and up to 6.7 mmol/l for the PA-D assay. In conclusion, the present multicenter evaluation demonstrates that the new procedures for the direct automation of C-HDL are easy and accurate and most of them correlated well with the classical precipitation method. In addition the study provides arguments for a choice between the different direct C-HDL methods.

Antibodies↗
PubMedDate not supplied

[Multicenter evaluation of four homogenous LDL-cholesterol assays].

International guidelines emphasize the importance of LDL cholesterol (LDL-C) assay in the care and follow-up of patients with cardiovascular risk. Most studies and common practice use Friedewald's formula for LDL-C calculation. The accuracy of the result depends closely on the precision of the input parameters (total cholesterol, triglycerides (TG) and HDL cholesterol), and discrepancies between calculated LDL-C and measurement by reference methods appear when TG exceed 4.5 mmol/L, or in the presence of abnormal lipoproteins. These restrictions and uncertainties in calculations have prompted the recent development of direct and homogeneous methods that fit all analyzers. A multicenter evaluation of four direct assays of LDL-C (Daiichi, Denka Seiken, Kyowa, Wako) was carried out on 45 serum samples (TG below 3.1 mmol/L) in eight laboratories using different analyzers. For three methods (Daiichi, Kyowa, Wako), the interlaboratory reproducibility was markedly improved relative to that of calculation. A strong correlation was found for all new methods when compared with a beta-quantification assay. Average bias in Denka Seiken assays was greater than Kyowa's and Daiichi's (although less dispersed for the latter) and for Wako all bias were positive. The relationship between bias variations and the lipid parameters of the samples was studied. Three methods, Daiichi, Kyowa and Wako, revealed a significant positive correlation between bias and serum VLDL-C/TG ratio, clearly indicating that cholesterol enrichment of VLDL was a source of variability in these assays. Specificity of the four methods was tested in situation of dyslipidemia by spiking isolated lipoproteins (chylomicrons, VLDL and HDL). This experiment revealed differences in behavior, most evidently upon addition of VLDL. No method was truly specific, but up to 8 mmol/L of TG the variations were acceptable. In the presence of type III hyperlipoproteinemia, however, only the Denka Seiken method was reliable. Linearity up to 20 mmol/L (Daiichi, Denka Seiken) or 14 mmol/L (Kyowa, Wako) of LDL-C allows these tests to be used in main routine cases. New direct assays are an obvious technological advance in terms of analytical performance and conveniency. Their use for the diagnosis and follow-up of hyperlipidemic patients offers an alternative that overcomes the limitations of the Friedewald calculation.

Blood Chemical Analysis↗
PubMedDate not supplied

[Reference values of apolipoproteins A1 and B. Contribution of international standardization. Travail collaboratif entre la SFBC, l'Arcol et le SFRL].

The utilization of two WHO reference materials, liquid and lyophilized, permitted international standardization of apolipoprotein measurements. We report here the results of a collaborative study between Arcol, SFBC and SFRL in order to establish reference ranges for apo A1 and B on nine standardized systems. A population of 1027 men and women supposed healthy, 4 to 60 year old, have been selected in two Centers for Preventive Medicine. The serum samples were aliquoted frozen at -20 degrees C the day of sampling and analysed by the manufacturers with IFCC standardized calibrants. A specific quality control was performed using a frozen pool of sera. For apo A1, the centile 2.5 of the reference population varies from 1.04 to 1.16 g/l. The range values for the centile 97.5 varies from 1.87 to 2.24 g/l. For apoB, the centile 2.5 varies from 0.43 to 0.57 g/l, and the centile 97.5 from 1.30 to 1.39 g/l. Only one system has a problem of dispersion with an upper limit equal to 1.20 g/l. These results improve that international standardization allowed actually a good comparability of the results, especially for apoB.

Adolescent↗