Jean-Roger Claude

Relationship of plasma insulin levels to the incidence of myocardial infarction and coronary heart disease mortality in a middle-aged population.

SummaryThe possible role of plasma insulin levels as a risk factor of coronary heart disease has been studied in a population of 7246 non diabetic, working men, aged 43–54 years, initially free from heart disease, and followed for 63 months on average. 128 new coronary heart disease events (non fatal myocardial infarction and coronary related deaths) were detected during this period. The annual risk is analysed by a multivariate model including age, serum cholesterol and triglycerides, blood pressure, smoking, obesity, plasma glucose and insulin fasting and 2 hours after a 75 g oral glucose load. It is shown that the fasting plasma insulin level and the fasting insulin-glucose ratio are positively associated with risk independent of the other factors. The same variables, 2 hours after the glucose load are also positively associated with risk but their contributions are not significant in the multivariate analysis. It is concluded that high insulin levels may constitute an independent risk factor for coronary heart disease complications in middle aged non diabetic men.

Hypertriglyceridaemia as a risk factor of coronary heart disease mortality in subjects with impaired glucose tolerance or diabetes

SummaryThe Paris Prospective Study is a long-term investigation of the incidence of coronary heart disease in a large population of working men. The first follow-up examination involved 7,038 men, aged 43–54 years. Subjects with impaired glucose tolerance or diabetes (n=943) were selected from the total population for a separate analysis of coronary heart disease mortality risk factors. During a mean follow-up of 11 years, 26 of these 943 subjects with abnormal glucose tolerance died from coronary heart disease. Univariate analysis showed that plasma triglyceride level (p<0.006), plasma cholesterol level (p<0.02), and plasma insulin level both fasting and 2-h post-glucose load (p<0.02), were significantly higher in subjects who died from coronary heart disease compared to those who did not. In multivariate regression analysis using the Cox model, plasma triglyceride level was the only factor positively and significantly associated with coronary death. The distribution of plasma triglyceride levels was clearly higher for the subjects who died from coronary heart disease compared to those who did not die from this cause or were alive at the end of the follow-up. This new epidemiological evidence that hypertriglyceridaemia is an important predictor of coronary heart disease mortality in subjects with impaired glucose tolerance or diabetes suggests a possible role of dyslipidaemia in the excessive occurrence of atherosclerotic vascular disease in this category of subjects.

Hyperinsulinaemia as a predictor of coronary heart disease mortality in a healthy population: the Paris Prospective Study, 15-year follow-up

SummaryThe Paris Prospective Study is a long-term, largescale study of the factors predicting coronary heart disease. The first follow-up examination included, for subjects not known as having diabetes mellitus, a 75 g oral glucose tolerance test with measurement of plasma insulin and glucose levels, fasting and 2 h post-load. Between 1968 and 1973, 6903 men aged 43–54 years were thus examined. Causes of death were ascertained within this group after 15 years of mean follow-up. The baseline variables were tested as predictors of death from coronary heart disease by a Cox regression analysis. Significant independent predictors of coronary heart disease death were: systolic blood pressure, number of cigarettes per day, plasma cholesterol level, and 2 h post-load plasma insulin level when entered as a categorical variable (below or above 452 pmol/l, i.e. the lower limit of the fifth quintile of the distribution). This dichotomization was performed to account for the non-linear univariate distribution of deaths with increasing post-load insulin values. Fasting plasma insulin level was not an independent predictor of death by coronary heart disease over this long-term follow-up. Levels of blood glucose were not significant independent predictors of death by coronary heart disease when plasma insulin levels were included in the model. The same applied to abnormalities of glucose tolerance when the 125 men with known non-insulin-treated diabetes at baseline were added to the group. Under the assumption that hyperinsulinaemia is a marker of insulin resistance, the results are consistent with the hypothesis that insulin resistance is associated with a higher risk of coronary heart disease mortality. However, it is doubtful that circulating insulin per se is a direct cause of arterial complications.

The role of non-esterified fatty acids in the deterioration of glucose tolerance in Caucasian subjects: results of the Paris Prospective Study

Summary Although an increased plasma non-esterified fatty acid (NEFA) concentration has been shown to increase insulin resistance (Randle cycle), decrease insulin secretion and increase hepatic gluconeogenesis, the effect of NEFA on the deterioration of glucose tolerance has not been studied prospectively in Caucasian subjects. Therefore, we investigated whether plasma NEFA may be regarded as predictors of deterioration of glucose tolerance in subjects with normal (NGT, n = 3671) or impaired (IGT, n = 418) glucose tolerance who were participants in the Paris Prospective study. The subjects were first examined between 1967 and 1972 and underwent two 75-g oral glucose tolerance tests 2 years apart with measurements of plasma glucose, insulin and NEFA concentrations. Glucose tolerance deteriorated from NGT to IGT or non-insulin-dependent diabetes (NIDDM) in 177 subjects and from IGT to NIDDM in 32 subjects. In multivariate analysis, high fasting plasma NEFA in NGT subjects and high 2-h plasma NEFA and low 2-h plasma insulin concentrations in IGT subjects were significant independent predictors of deterioration along with older age, high fasting and 2-h plasma glucose concentrations and high iliac to thigh ratio. When subjects were divided by tertiles of plasma NEFA concentration at baseline, there was an increase in 2-h glucose concentration with increasing NEFA in the subjects who did not deteriorate, but no effect of plasma NEFA in those who deteriorated. In subjects with IGT who deteriorated compared with those who did not 2-h plasma insulin concentration was lower but there was no evidence that this resulted from an effect of plasma NEFA. Our data suggest that a high plasma NEFA concentration is a risk marker for deterioration of glucose tolerance independent of the insulin resistance or the insulin secretion defect that characterize subjects at risk for NIDDM. [Diabetologia (1997) 40: 1101–1106]

High-performance liquid chromatographic determination of (S)- and (R)-propanolol in human plasma and urine with a chiral β-cyclodextrin bonded phase

The determination of propranolol enantiomers in microsamples of human plasma and urine by HPLC using a chiral stationary phase is described. After extraction from 200 microliters of plasma or urine with racemic alprenolol as internal standard (I.S.), the enantiomers are separated on a beta-cyclodextrin column with a polar organic mobile phase and determined by fluorescence detection. The retention times of I.S. and propranolol enantiomers are about 12-13 min and 16-18 min, respectively. Peak resolutions are 1.4 for I.S. and 2.2 for propranolol. The use of alprenolol as I.S. improves significantly the coefficients of variation (C.V.: 0.6-4.2%). Sensitivity is approximately 1.5 ng/ml per propranolol enantiomer. The assay is applied to pharmacokinetic studies of racemic propranolol in human biological fluids. The (S)-propranolol levels are always higher than the (R)-antipode concentrations in plasma and urine.

Enantioselective high-performance liquid chromatography determination of methadone enantiomers and its major metabolite in human biological fluids using a new derivatized cyclodextrin-bonded phase

The simultaneous determination of methadone (Mtd) enantiomers and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), in human urine and serum by enantioselective HPLC using a new Cyclobond 1-2000 RSP column is described. After alkaline extraction from urine or serum with estazolam as an internal standard, Mtd enantiomers and its metabolite (EDDP) are separated on the previous column with reversed-mobile phase and detected at 210 nm. Peak resolutions are about 2.0 for Mtd enantiomers. The relative standard deviations (R.S.D.) of Mtd and EDDP standards are between 0.5 and 4.5%. Most drugs of abuse are shown not to interfere with this technique. The method has been applied to study the levels of each Mtd enantiomer and of its racemic metabolite in urine and serum of patients under maintenance treatment for opiate dependence. In urine, R-(-)-Mtd levels are always higher (about 2+/-0.5-fold) than those of S-(+)-Mtd and in most cases, metabolite concentrations are greater than those of global Mtd enantiomers. However, the R-(-) enantiomer levels of residual drug in serum of some patients were lower than those of its antipode. This method is suitable for pharmacokinetic and toxicological studies of Mtd enantiomers and its major metabolite in biological fluids.

Modulation of energy status and cytotoxicity induced by FK506 and cyclosporin A in a renal epithelial cell line

Abstract FK506 and cyclosporin A (CsA) are two potent immunosupressants with similar toxicity profile. Nephrotoxicity is the main adverse effect of both compounds. The aim of this study is to compare the in vitro nephrotoxic effects on renal epithelial cell line LLC-PK1 by measuring cell viability and energy status as evaluated by concentrations of ATP and ATP metabolites. Cell viability (expressed as IC50 was assessed via thiazolyl blue (MTT) assay after incubation for 4–24 h with FK506 or CsA. ATP and its metabolites were determined by HPLC after 4 and 6 h incubation with FK506 or CsA alone at the respective IC50. Both FK506 and CsA decreased cell viability to similar extents, in a dose- and time-dependent manner. After 4 h incubation, both drugs decreased ATP levels (−25%) and increased uric acid levels. However, the latter percentage increase was twofold higher with CsA (18%) than with FK506 (9%). The energy charge, calculated according to levels of adenine nucleotides, was decreased by 10% in FK506-treated cells and by 27% in CsA-treated cells. At the end of 6-h incubation, FK506-treated cells maintained ATP levels coupled with energy charge at near control levels whereas the levels were 32% lower in CsA treated cells. Compared to the 4 h-incubation, the increase in uric acid was similar for FK506 but was doubled with CsA. The decrease in cell integrity and ATP depletion induced by CsA in LLC-PK1 cells was only transiently observed with FK506. By preserving energy status, FK506 leads to fewer metabolic disturbances than CsA in the renal epithelial cell line LLC-PK1, demonstrating a minor potential nephrotoxicity.

Rapid determination of methadone and its major metabolite in biological fluids by gas–liquid chromatography with thermionic detection for maintenance treatment of opiate addicts

A rapid gas-liquid chromatographic assay is developed for the quantification of methadone (Mtd) and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), in biological fluids of opiate addicts. After alkaline extraction from samples with lidocaine hydrochloride as internal standard, Mtd and EDDP are separated on SP-2250 column at 220 degrees C and detected with a thermionic detector. The chromatographic time is about 6 min. The relative standard deviations (R.S.D.) of Mtd and EDDP standards are between 1.5 and 5.5%. Most drugs of abuse (morphine, codeine, narcotine, cocaine, benzoylecgonine, cocaethylene, dextropropoxyphene etc) are shown not to interfere with this technique. The method has been applied to study the levels of Mtd and EDDP metabolite in serum, saliva and urine of patients under maintenance treatment for opiate dependence. EDDP levels were found higher than those of Mtd in urine samples from four treated patients, but lower in serum and undetectable in saliva. However, Mtd concentrations were higher in saliva than in serum.

Cardiovascular and alcohol-related deaths in abnormal glucose tolerant and diabetic subjects

SummaryThe aim of this study was to compare the causes of death and parameters related to alcohol consumption, between subjects diagnosed as diabetic, clinically by their general practitioner, or glucose intolerant and in particular as diabetic, using the epidemiological criteria of an abnormal glucose level following an oral glucose tolerance test. The subjects in this study were 7035 working men, aged between 44 and 55 years, who attended the first follow-up examination of the Paris Prospective Study, between 1968 and 1973. They were classified as ‘clinically diagnosed diabetic’ or, following an oral glucose tolerance test and the World Health Organisation criteria, as having ‘oral glucose tolerance test diagnosed diabetes’, impaired glucose tolerance or normoglycaemia. The relative risk of death by cirrhosis, in comparison with the normoglycaemic group, was 21 (95 % confidence interval: 9.1–49) in the group diagnosed diabetic by the oral glucose tolerance test, significantly different (p < 0.02) from the group diagnosed diabetic clinically 3.1 (0.41–24); factors indicative of excessive alcohol consumption at baseline differed accordingly. In contrast, the relative risks for death by coronary heart disease were similar, 2.1 (1.0–4.1) and 2.7 (1.4–5.4) respectively; all of the factors defining the insulin resistance ‘Syndrome X’ (hyperglycaemia, hyperinsulinaemia, hypertension, hyperlipidaemia and also central obesity) and predictive of coronary heart disease were elevated in both groups of diabetic subjects. ‘Diabetes’, as diagnosed by the oral glucose tolerance test, might be the consequence of excessive alcohol consumption which could lead to insulin resistance, then to coronary heart disease, as well as to alcohol-related diseases.

Separation of oxazepam, lorazepam, and temazepam enantiomers by HPLC on a derivatized cyclodextrin-bonded phase: application to the determination of oxazepam in plasma

The enantioselective high-performance liquid chromatography (HPLC) of three racemic 3-hydroxybenzodiazepines, oxazepam (Oxa), lorazepam (Lor), and temazepam (Tem), is a difficult operation because of the spontaneous chiral inversion in polar solvent. To solve this problem, we have developed an HPLC method based on a chiral Cyclobond I-2000 RSP column, maintained at 12 degrees C, and a reversed mobile phase (acetonitrile in 1% triethylamine acetate buffer, TEAA) at a flow rate of 0.4 ml/min. Peaks were detected by a photodiode-array detector at 230 nm for quantification and by an optical rotation detector for identification of (+) and (-) enantiomers. The results showed that peak resolutions of Oxa, Lor, and Tem enantiomers, analyzed under the same conditions, were 3.2, 2.0, and 1.8, respectively. For the determination of Oxa enantiomers in plasma of rabbits, extraction with diethyl ether at pH 1.5, a polar organic mobile phase, and a Cyclobond I-2000 SP column were used. Other analytical conditions were the same as previously described. Blood samples were immediately cooled at 4 degrees C and centrifuged at 0 degrees C for the collection of plasma. The results showed a difference in plasma S(+)- and R(-)-oxazepam concentrations in rabbits. No racemization of S(+)- or R(-)-Oxa enantiomers, added alone to blank plasma, was observed after extraction and enantioselective HPLC analysis.