Comparison of HbA1 and fructosamine in diagnosis of glucose-tolerance abnormalities.

Total glycosylated hemoglobin (HbA1) and fructosamine were evaluated as screening tools for detection of glucose-tolerance abnormalities in 144 asymptomatic subjects undergoing a 75-g oral glucose tolerance test. Subjects were classified according to World Health Organization criteria as having normal (n = 78), impaired (n = 40), or diabetic (n = 26) glucose tolerance. We found good specificity for HbA1 and fructosamine (100 and 97%, respectively) but low sensitivity (15 and 19%, respectively). At the intersection of the curves of sensitivity and specificity drawn from various thresholds of normality, both sensitivity and specificity were 75% for HbA1 and 55% for fructosamine. Thus, neither HbA1 nor fructosamine seems to be suitable for the diagnosis of mild abnormalities in glucose tolerance.

Lipoprotein(a) in diabetic patients with and without chronic renal failure.

OBJECTIVE: To examine the distribution of Lp(a) plasma levels in patients with IDDM and NIDDM, and in nondiabetic and IDDM patients with chronic renal failure. RESEARCH DESIGN AND METHODS: Cross-sectional study of Lp(a) plasma levels in a population of diabetic patients with stable metabolic control, with simultaneous determination of plasma lipids, fasting plasma glucose, and HbA1. Thirty-six patients with IDDM, 90 with NIDDM, and 41 with chronic renal failure (20 IDDM, 21 nondiabetic) were compared with 78 control subjects. RESULTS: Lp(a) plasma levels were significantly higher in IDDM and NIDDM patients, as well as in nondiabetic and IDDM patients with chronic renal failure compared with control subjects. No correlation was observed between Lp(a) and lipid plasma levels, fasting plasma glucose, and HbA1. CONCLUSIONS: Lp(a) may contribute to the increased prevalence of atherosclerotic disease in diabetic patients and patients with chronic renal failure, especially in IDDM patients whose lipoprotein pattern was not different from that of the control group.

[Influence of phosphatidylcholine/cholesterol molar ratios in liposomes on cholesterol reactivity with cholesterol:oxygen oxidoreductase]. / Influence du rapport molaire phosphatidylcholines/cholestérol des liposomes sur la réactivité du cholestérol à la cholestérol : oxygène oxydorèductase.

The reactivity of sonicated phosphatidylcholine-cholesterol liposomes with cholesterol : oxygene oxydoreductase, an enzyme which catalyses the oxidation of the 3 beta hydroxyl group of cholesterol to a ketone group, is compared with that of ternary system phosphatidylcholine-cholesterol-Thesit. Regardless to the phosphatidylcholines nature and the phosphatidylcholine/cholesterol molar ratio (R), the enzymatic oxidation rate of liposomal cholesterol is slower than when the reaction is developed in the present of Thesit, a surfactif agent which destroyes the lamellar particles. This is true whether Thesit is added during preparation of dispersions or during incubation with cholesterol oxydase. The enzymatic oxydation rate of cholesterol of ternary systems phosphatidylcholine-cholesterol-Thesit is independent of the (R) value and the phosphatidylcholine fatty acid unsaturation, whereas that of phosphatidylcholine-cholesterol dispersions depends on these two parameters. The reaction rate increases in the order: dipalmitoylphosphatidylcholine to yolk egg phosphatidylcholines, and dioleylphosphatidylcholine. The optimal conditions for cholesterol oxidation were found to be R = 0.5. This result is not affected by the phosphatidylcholines nature. In order to explain these data, various hypotheses are considered. In particular, the weak liposomal cholesterol reactivity with cholesterol oxidase could result from an inhibitory effect on the enzyme-substrate combination due to the polar phosphorylcholine groups.

Electrophoretic study of the physico-chemical characteristics of Bence-Jones proteinuria and its association with kidney damage.

AIM: To identify a physico-chemical criterion, or set of criteria, explaining and possibly predicting the nephrotoxic behaviour of Bence-Jones proteins (BJP). METHODS: The electrophoretic mobility and isoelectric point (pI) of 92 BJP isolates were determined using various electrophoresis procedures on polyacrylamide gel. The proportions of monomers and dimers were determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS PAGE) in 58 cases. PAGE data for 10 BJP isolates were used to construct Ferguson plots and titration curves. RESULTS: The distribution of electrophoretic mobility and pI values was bimodal and showed a positive correlation when the pI was above 6. The values of these two parameters in 22 patients with renal impairment were not significantly different from those in the patients without renal impairment, and the statistical analysis showed no predictive value for the onset of renal impairment. However, patients excreting the lambda light chain isotype had a 2.8-fold higher risk of developing renal impairment compared with the other patients. Studies of the charge variation of the protein with pH indicated three types of behaviour, suggesting that the charge of BJP is highly variable at physiological pH. CONCLUSION: It is important to study not only the positivity or negativity of the BJP charge at a given pH, but also its intensity. The study of the BJP titration curves in patients with renal impairment suggests that a low charge at physiological urinary pH could predict renal impairment.

Discrepancies between lipoprotein(a) concentrations in icteric sera measured by immunonephelometry and electroimmunodiffusion.

We compared the lipoprotein(a) [Lp(a)] levels in 32 icteric sera determined both by an electroimmunodiffusion assay (EIA), using the Hydragel Lp(a) kit (Sebia, France) and by two immunonephelometric assays, one on a Behring Nephelometer Analyzer (BNA), using antiserum from immunofrance, and the other on a Beckman analyzer (Array), using antiserum from Dako (Denmark). With the EIA assay, the Lp(a) level was 0.09 +/- 0.09 (mean +/- SD in g/L), with the BNA assay, 1.01 +/- 1.51 and with the Array assay, 0.05 +/- 0.05. Sample blanks values (0.76 +/- 1.28 g/L) demonstrated that the high Lp(a) levels obtained in the BNA assay are caused by nonspecific precipitation. Analysis of the precipitate indicated the presence of Lipoprotein X, an abnormal lipoprotein that appears in the serum of patients with obstructive jaundice or with lecithin-cholesterol acyltransferase deficiency. The precipitant seems to be polyethyleneglycol (PEG) that was added to the reaction medium in both the BNA and the Array assays to stabilize the Lp(a)-anti Lp(a) immune complex. In the Array assay, interference by this nonspecific precipitation is eliminated by preliminary centrifugation of the diluted sample. However, coprecipitation of Lp(a) could occur during this step. Consequently, the results of Lp(a) measurement in serum from patients with hepatobiliary diseases should be interpreted with caution when immunonephelometric assays are used with a medium containing PEG.

A sequential and simple determination of zinc, copper and aluminium in blood samples by inductively coupled plasma atomic emission spectrometry.

A sequential method of measuring zinc, copper and aluminium in serum by inductively coupled plasma (ICP) spectrometry is described. It involves a 1/5 dilution of serum with a potassium chloride solution which enhances aluminium signal intensity and reduces variations between different matrix compositions. The method is as sensitive as atomic absorption for zinc (sensitivity: 0.11 mumol/l) and copper (sensitivity: 0.020 mumol/l) and can also be applied to monitor aluminium (sensitivity: 0.12 mumol/l) for patients receiving total nutrition therapy or hemodialysis. Its linearity extends at least to 200 mumol/l for copper and zinc and to 20 mumol/l for aluminium. The correlations with atomic absorption are satisfactory for the 3 parameters, as assessed by the correlation coefficients established for both methods. A reference interval was established with 34 sera of control subjects (19 men, 15 women) which showed an average zinc, copper and aluminium of 14.5 (S.D. 2.6), 17.3 (S.D. 2.1) and 0.32 (S.D. 0.12) mumol/l, respectively. This method does not require a simultaneous ICP spectrometer and can be performed with 1 ml of serum in a single tube, using a routine sequential ICP spectrometer.

Relationship between hair, serum and bone aluminium in hemodialyzed patients.

To establish the predictive value in osteodystrophy of hair aluminium content in patients on hemodialysis, we compared the aluminium levels in serum, cortical and trabecular bone and hair of 40 such patients with the levels in 23 healthy controls. In the patients, mean hair aluminium content was significantly higher than the controls (0.226 mumol/g, range: 0.09-0.500 mumol/g, n = 39 versus 0.126 mumol/g, range: 0.020-0.330 mumol/g, n = 49) but there was a large overlap between the two groups. The patients exhibited a significant correlation between serum and cortical bone aluminium measured by atomic absorption spectrometry (rs = 0.67, n = 37, p less than 0.05), but no correlation between aluminium in hair and in serum or bone, whether cortical or trabecular. Bone histomorphometric studies also indicated that unlike aluminium levels in cortical or trabecular bone, its levels in hair are not predictive of aluminium-induced osteomalacia. Consequently, hair aluminium cannot suitably replace bone and serum aluminium as a criterion of osteodystrophy in hemodialyzed patients.

Variations in HDL and VLDL levels chronic alcoholics. Influence of the degree of liver damage and of withdrawal of alcohol.

Changes in plasma HDL and VLDL levels were investigated in 284 chronic alcoholics staying in a Detoxification Centre where they initiated or continued abstinence. The data show that the variations in plasma HDL are modulated by the degree of liver injury. In severe hepatic damage HDL levels are sharply decreased. An alcohol-induced rise in HDL can occur in the only subjects with no signs of hepatic insufficiency. This elevation is rapidly reversible after withdrawal of alcohol. Such a rise might reflect enhanced synthesis and release by liver but might also be due to an accelerated turnover of the VLDL.

Enhanced susceptibility of low-density lipoprotein to in vitro oxidation in type 1 and type 2 diabetic patients.

Macrovascular disease represents a major cause of morbidity and mortality in patients with diabetes mellitus. Low-density lipoprotein (LDL) is involved in the pathogenesis of atherosclerotic lesions, through modifying processes such as oxidation. We examined the in vitro susceptibility to oxidation and the oxidizability of LDL isolated from the plasma of Type 1 and Type 2 diabetic patients. Two groups of diabetic patients (20 Type 1, 20 Type 2) were compared with sex- and age-matched non-diabetic control groups. In vitro oxidation of the purified LDL preparations was assessed by determination of the kinetics for the formation of conjugated dienes (lag phase duration, maximal rate and maximal dienes concentration) and by measurement of thiobarbituric acid-reacting substances (TBARS) in the presence of copper ions. LDL from both Type 1 and Type 2 diabetic patients exhibited a shorter lag phase duration for conjugated dienes formation (94 +/- 14 vs. 108 +/- 20 and 97 +/- 26 vs. 112 +/- 18 min for Type 1 and Type 2 diabetic groups vs. respective control groups, P < 0.05). We also observed an increase in maximal rate of conjugated dienes formation (2.21 +/- 0.55 vs. 1.52 +/- 0.31 and 2.02 +/- 0.55 vs. 1.52 +/- 0.31 nmol/mg LDL/min, P < 0.01) and of maximal production of TBARS (77.9 +/- 11.8 vs. 65.5 +/- 10.4 and 76.7 +/- 9.9 vs. 65.3 +/- 9.4 nmol/mg LDL protein, P < 0.05) in diabetic groups. Our results demonstrate both a higher susceptibility to oxidation and a higher oxidizability of LDL from diabetic patients, as much for Type 1 as Type 2 diabetic subjects with or without pre-existent vascular complications. This enhanced propensity of LDL oxidation in patients with diabetes mellitus could at least partly be attributable to quantitative and qualitative alterations in the chemical composition of LDL and to the glycoxidation process occurring on these lipoproteins.

Cyclosporin-A inhibits human endothelial cells proliferation through interleukin-6-dependent mechanisms.

Cyclosporine A (CsA) is a widely used immunosuppressant which possesses significant side effects including nephrotoxicity and systemic arterial hypertension. In this work we evaluated the effects of CsA on human umbilical endothelial cell proliferation (HUVEC). Treatment of endothelial cells with CsA inhibited cell proliferation, and was correlated with an increase of interleukin-6 (IL-6) production and IL-6 mRNA expression. Addition of exogenous IL-6 also significantly altered cell proliferation. Furthermore, neutralization of endogenous IL-6 with a specific monoclonal antibody concomitantly with CsA treatment completely restored HUVEC proliferation. These results suggest that CsA-induced inhibition of HUVEC proliferation is mediated through an augmentation of IL-6 synthesis.

Use of a renal tubule cell line (LLC-PK1) to study the nephrotoxic potential of a kappa-type Bence-Jones protein.

The cytotoxicity of a Bence-Jones protein was assessed using a porcine renal tubule cell line (LLC-PK1), with the aim of developing a model for studying the potential nephrotoxicity of these proteins. The effects of a kappa Bence-Jones protein on cell viability were studied by means of biochemical methods (supravital dye uptake and measurement of cellular enzyme activities) and morphological electron microscopy. After a 24-h-treatment with Bence-Jones protein, a moderate cytotoxicity (about 15%) was noted but only a minor difference compared to treatment with bovine albumin in the same conditions. The morphological study showed a few cells in the process of lysis, but their numbers were insufficient for the demonstration of a clear cytotoxic effect. Immunocytochemical studies showed Bence-Jones protein fixation on some cells, especially on the outer membrane. Labeling of the hyaloplasm and basal pole of a few cells pointed to internalization of protein by LLC-PK1 cells. Although the cytotoxicity of the Bence-Jones protein tested here was only moderate, the use of this model enabled its cytotoxic effect to be distinguished from that of beta-lactoglobulin. This isolate could serve as a "moderate control" for a later study with a BJP having caused acute renal failure.

Physiological chromium determination in serum by Zeeman graphite furnace atomic absorption spectrometry. A serious challenge.

Several authors have already underlined chromium implication in glucose and lipids metabolism of humans. In this field, physiological chromium determination in serum could be helpful, but the discrepancies reported in numerous papers are confusing. Here we report some results obtained by Zeeman correction Graphite Furnace Atomic Absorption Spectrometry. This technique includes a dilution of serum with 12.5 mM ultrapure nitric acid and 0.25% Triton X-100 (final concentrations). Some main features can be outlined: (1) the contamination constitutes a serious drawback and (2) the sensitivity of the technique is critical (characteristic mass found: 1.76 pg/0.0044 A.s). Our results obtained from 27 healthy subjects (2.01 +/- 0.77 nmol/L) agree with most recent studies and indicate that serum chromium level does not seem to be sex-related.

A pentaplex automated fluorescent typing system for forensic identification and French Caucasian population data.

The polymerase chain reaction (PCR) amplification of short tandem repeat (STR) loci has already proven to be a method of choice for large scale typing of DNA samples in which the conventional restriction fragment length polymorphism (RFLP) technique is ineffective. A quadruplex PCR including HUMvWFA31A, HUMF13A01, HUMTH01, and HUMFESFPS STR loci is used successfully for routine forensic applications in our laboratory. However, the need to increase the discrimination power of the PCR systems used prompted us to develop a second system of a pentaplex PCR for the analysis of 4 additional STR loci (HUMD8S1179, HUMD18S51, HUMD21S11, and HUMFIBRA) and the sex determination by amplification of a segment of the X-Y homologous Amelogenin gene. Allele and phenotype frequencies for these 4 STR systems were obtained by multiplex amplification, from approximately 200 randomly selected and unrelated French Caucasian individuals. Statistical calculations for these phenotype distributions met expectations for Hardy-Weinberg equilibrium. Furthermore, the French allelic frequencies of D18S51, D21S11, and HUMFIBRA loci were compared with the data obtained by the Forensic Science Service (UK) for the British Caucasian population and proved to be similar.

[Lipoprotein (a)]. / La lipoprotéine (a).

Lp(a) or pre-beta 1-lipoprotein or Sinking pre-beta LP (SPB) is a special LP. Its very high density (1050 to 1120) means that it can be extracted from LDL and HDL. In common with the LDL, it possesses apo B and a similar size. It is characterized by the presence of specific apoproteins, non-immunoreactive albumin and a carbohydrate chain rich in sialic acid. Its transmission is hereditary; there is a major locus transmitted by autosomal dominant inheritance. Another hypothesis suggests that it is transmitted autosomally according to a polygenic mechanism for 75 p. cent of the molecule with superimposition of non-genetic elements for the rest. Lp(a) is not a product of Lp(b) metabolism; it is not transformed into any other LP and it does not exchange its apoproteins. Its synthesis is constant over time and its function is not yet known. Its assay depends on the antigenicity of the specific determinants of the apo Lp(a). Only radio-immunoassay is able to give values for any sample size especially for levels of less than 50 to 80 mg/l (respective limits of the EID and IDR techniques). It appears that a high Lp(a) level could constitute an additional risk to developing coronary heart disease and the limit beyond which this risk exists could be 300 mg/l in normolipidaemic subjects. The in vitro binding of LP to glycoaminoglycanes (GAG) could be a model for studying LP binding in vivo. It has been seen that, by the intermediary of a low concentration of Ca++ ions, the reactivity of Lp(a) to GAG was selective.

[the application of immunofixation on cellulose acetate in the rapid classification of biclonal immunoglobulinopathies (author's transl)]. / Application de l'immunofixation sur acétate de cellulose pour la classification rapide des immunoglobulinopathies biclonales.

The authors described a technique of immunofixation using standard cellulose acetate electrophoresis equipment. Using two cases of biclonal immunoglobulins (IgG + IgA and IgG + IgM) showing difficulties in interpretation by immunoelectrophoresis, they show how immunofixation may be used as a complement to immunoelectrophoresis.

[Proposal of a new procedure for the exploration of hepatocellular function. The trimethoxybenzene test (TMB)]. / Proposition d'un nouveau procédé d'exploration de la fonction hépatocellulaire. Le "test au triméthoxybenzène" (TMB)

The authors propose a new method of exploration of liver cell function based on the study of demethylation of a rapidly assimilated atoxic compound, trimethoxybenzene (TMB) in dimethoxy-hydroxybenzene (DMHB). Whereas in normal subjects, the urinary excretion of the metabolites was rapid and marked, 180 mg within 3 hours after taking a 400 mg dose, in patients with liver cell failure, the excretion of DMHB was considerably reduced, 80 to 95% in cirrhosis.

[Contribution of Jacques Canal in the field of lipoproteins]. / Contribution apportée par Jacques Canal dans le domaine des lipoprotéines.

The scientific works of J. Canal have essentially related to low density lipoproteins (L.D.L.), between 1.025 and 1.050. By using proteolytic enzymes and phospholipases, he is able to obtain informations on the accessibility of apolipoprotein B and phospholipids. So, as early as 1975, he expresses the hypothesis that only 30 p. cent of Apo B occupy a superficial position. In addition, he proposes the fact that Apo B has at least four antigenic determinants; this hypothesis formulated by J. Canal, almost 10 years ago, was recently confirmed by using monoclonal antibodies. At the same time, using phospholipases, J. Canal reaches the conclusion that phospholipids are localized on the surface of L.D.L. He demonstrates that phospholipids play a major role in the precipitation of L.D.L. by sulfate polysaccharides in the presence of L.D.L. by sulfated polysaccharides in the presence of divalent cations (Reaction of Burnstein). He proposes a mechanism for this reaction. This research on the mechanism of Burnstein's reaction will receive in clinical biochemistry an important application with the development of a completely original technique of dosage of total lipids in the serum.

[Assay of cystine aminopeptidase activity on a centrifuge analyser]. / Dosage de l'activité cystine-aminopeptidase sérique sur analyseur centrifuge.

The assay of the serum cystine-aminopeptidase activity, of placental origin, is a useful test for monitoring pregnancy. The authors present an adaptation of Van Oudheusen's method on a centrifuge analyser which allows a rapid kinetic measurement of this activity and they justify their choice of procedure. The values obtained in non-pregnant women and in pregnancies of between 8 and 40 weeks of amenorrhoea are presented.

[Study of the specificity of action of cholesterol oxygen oxidoreductase on various sterols and related substances]. / Etude de la spécificité d'action de la cholestérol oxygène oxydoréductase sur certains stérols et substances apparentées

The authors studied the action of oxygen cholesterol oxidoreductase (E.C. 1.1.3.6) extracted from Nocardia erythropolis on different sterols following simultaneously:--the disappearance of the substrate by chromatography on thin layers of silic acid, the formation of hydrogen peroxide by Röschlau's reaction, changes in the absorption spectrum between 220 and 320 nm. The results obtained show that sterol oxidase presents a broad spectrum of activity. It catalyses the transformation into ketone of the secondary alcohol group at the 3 beta position of sterols which possess in the C17 position a lateral chain of at least two carbon atoms. In the other hand, the reaction does not take place if there exists in the C5 position, an H in the cis position or if two hydrogen atoms linked to carbon 4 are substituted. Finally, only oxidation products derived from sterols possess a double bond situated in the 4-5 or 5-6 position presenting an absorption band between 240 and 250 nm.

[Comparison of protein concentrations in saliva and serum]. / Comparaison des concentrations protéiques de la salive et du sérum.

Saliva and serum protein profiles composed of 12 proteins: IgA, IgG, IgM, albumin, transferrin, alpha 1-glycoprotein acid, alpha 2-macroglobulin, alpha 1-proteinase inhibitor, haptoglobine, C3C, C4 and CRP were obtained by laser nephelometry of aliquots of samples of non-stimulated whole saliva and blood taken at the same time. The population of 138 controls of both sexes was divided into 4 age groups: 1 (20 to 29 years), 2 (30 to 39 years), 3 (40 to 49 years), 4 (50 to 60 years). Using the techniques developed for saliva assay, 10 proteins were measurable: IgA, IgG, IgM, albumin, transferrin, alpha 1-glycoprotein acid, alpha 2-macroglobulin, alpha 1-proteinase inhibitor, haptoglobulin and C3C. The C4 fraction and CRP were present at concentrations lower than the detection limit i.e. at 1.8 and 2.05 mg/l. In the serum 11 proteins were analysed, CRP occurring at less than 0.01 g/l. The statistical two-factor variance analysis test (sex and age) demonstrated the statistically significant influence of age in the saliva for alpha 1-PI and alpha 2-M in the serum for Tf, alpha 2-M and alpha 1-PI, and sex in the serum for IgG, IgM, alpha 1-PI, alpha 2-M and also the interaction of both factors in the serum for alpha 2-M.