[Measurement of urinary free cotinine. Comparison with the level of expired air carbon monoxide]. / Dosage de la cotinine urinaire libre. Deuxième partie: comparaison avec le taux de monoxyde de carbone dans l'air expiré.

BACKGROUND AND AIM: Cotinine is a very reliable index for the estimation of active or passive smoking. Sampling from a single urine void is well accepted by smokers who are willing to stop. It is not possible to exclude modification of urine cotinine according to beverage intake. The aim of this study was to determine if urine cotinine concentration must necessarily be adjusted to creatinine or not, by making comparison with expired air carbon monoxide. MATERIAL AND METHODS: Carbon monoxide was measured in 53 smokers coming for the first time in a smoking cessation program. Urine cotinine was measured by HPLC-UV. The cut-off value for abstinence is 8ppm and 0.05 mg/L, repectively. Urine creatinine was determined using the Jaffe reaction. RESULTS: Mean CO level was 18.5 +/- 10.6 ppm and mean urine cotine was 1.45 +/- 0.86 mg/L. Eight smokers had CO 8 ppm. They should be considered as abstinent. However, only one of them had a cotinine under the detection limit. Urine creatinine varied in a large range (0.7 - 35 mmol/L). But, cotinine was only weakly correlated to creatinine (r = 0.279, p = 0.037). There was a highly significant correlation between cotinine and CO (0.649, p = 0.0001). The correlation of cotinine/creatinine versus CO was not significant (r = 0.249, p = 0.072). In order to take into account fluid intake, urine cotinine of each sample was adjusted as if creatinine was equal to the mean (8.3 mmol/L) of the group of subjects. The correlation observed with adjusted or non adjusted cotinine and CO (r = 0.640, p < 0.0001) was the same. CONCLUSION: Urine cotinine from a single void is an accurate index of tobacco smoking at the individual level. There is no need to adjust cotinine concentration, taking into account urine creatinine. Measurement of urine cotinine can be useful to manage smokers who deliberately wish to overcome tobacco dependence, offering the opportunity to provide an adequate level of nicotine substitutive therapy. It is also of peculiar importance to follow-up pregnant women and smokers for whom cessation is required after a clinical event. Finally, absence of cotinine in urine can be used to document abstinence from tobacco products.

[Urinary cotinine and nicotine metabolites measurement]. / Dosage urinaire de la cotinine et des métabolites de la nicotine.

UNLABELLED: According to the recent regulations (Circulaire DGS/DH du 3 avril 2000), tobacco dependence must be determined by the measurement of urine nicotine metabolites. Various assay methods are presently available. They were tested in order to evaluate their analytical performances and to determine how they can be used for the clinical management of smoking cessation. MATERIAL AND METHODS: Urine samples from a single void (n = 97) were obtained from active and abstinent smokers (with or without nicotine substitutive therapy). They were all analyzed by the various methods. Cotinine concentration was measured in six laboratories, using HPLC combined with UV detection according to a standardized procedure (Ann Biol Clin 2002 : 60 : 263-72). Immunoassay methods were also tested and the values obtained from urine samples were compared to urine cotinine measured by HPLC-UV. RESULTS: HPLC-UV: Urinary cotinine varied in a range from undetectable to 4 mg/L. An interlaboratory comparison was performed according to the Valtec procedure (calculation of equation of Deming, chart of differences). There was a good accordance between laboratories. Cotinine concentration was only slightly influenced by fluid intake, as shown by a poorly significant correlation between cotinine and creatinine (r = 0.23, p = 0.05). Homogeneous immunoassays: The two homogeneous immunoassays (Cotinine) from Thermo Electron and Cotinine Enzyme Immunoassay commercialized by Microgenics were highly correlated (r = 0.97). The correlation was not so strong with HPLC-UV (r = 0.86). Firstly, values were found higher with immunoassays because antibodies crossreact with 3-hydroxycotinine. Secondly, the ratio of immunoassays values to HPLC-UV values varied according to urine specimens. Finally, there was a highly significant correlation with urine creatinine (r = 0.40, p = 0.0001), thus indicating the influence of fluid intake. Heterogeneous immunoassay: The kit Metabolites of Nicotine commercialized by DPC France was tested on the analyzer Immulite, using a procedure specifically established for urine. Antibodies revealed a large spectrum of nicotine metabolites. Therefore, the values were much higher than those observed for the same urine samples with homogeneous immunoassays. CONCLUSION: HPLC-UV can be recommended for the measurement of urinary cotinine, as it was shown a good accordance between laboratories. The low detection limit is of interest for the diagnosis of Environmental Tobacco Smoking. Homogeneous immunoassays can be easily used for routine analysis as they can be performed directly on urine specimen. The results must be interpreted according to cut-off values specifically established according to homogeneous or heterogeneous immunoassays. Variability induced by fluid intake must be taken into account. The interest of the heterogeneous immunoassay needs to be confirmed for the diagnosis of Environmental Tobacco Smoking.

[Sodium/iodide symporter: physiopathological aspects and therapeutic perspectives]. / Le symporteur sodium/iodure: données récentes et perspectives thérapeutiques.

The existence of the natriuric/iodide symporter (NIS) represents a new view to understand the thyroid metabolism of iodide. Due to its cellular localisation on basolateral membrane, this transporter exerts an essential role in the biological functions of the thyroid, especially the capacity to accumulate iodide into the thyrocytes. Clinical perspectives of NIS activity modulation would ameliorate the diagnosis and the treatment of thyroid diseases by using radioisotopes transported by the NIS (131 iodide, 99m technetium, 188 rhenium). The study of the regulation pathways modulating the expression and the activity of the symporter NIS, would allow to understand pathogeny of benign or malignant diseases of the thyroid gland. The relative facility of the therapy management by 131 iodide and its good efficiency associated to the recent advance of NIS function also give an interesting perspective to the gene therapy treatment of the nonthyroid cancers despite existent methodological problems.

[Analytical aspects of the semiquantitative determination of urinary iodine using ferroin: value of rapid screening for iodine deficiency or excess]. / Aspects méthodologiques de la détermination semi-quantitative de l'iodurie par la ferroïne: intérêt dans le dépistage rapide de carence ou surcharge en iode.

Iodine is an essential element for thyroid hormone synthesis. Iodine disorders induced biological and/to clinical expression of thyroid dysfunction. Inappropriate iodine intake (by default or by excess) is worrying in terms of public health in France regarding the iodine deficiency and the frequency of iatrogen iodine overloads. Urinary iodine determination which generally implicates the use of a cerimetric method, is an useful tool to evaluate iodine intakes. In this study, we described the analytical aspects of a semiquantitative method of urinary iodine using a redox indicator, ferroin. This method allows the screening of iodine excess or deficiency in a short time (< 3 hours) with a good specificity and sensitivity. Since this assay does not require specific apparatus, it could be easily developed in clinical chemistry laboratories for the detection of inappropriate iodine intakes, and could be useful for prevention programs of iodine deficiency.

[What perception have smokers of nicotine and tar yields of cigarettes?]. / Quelle perception ont les fumeurs des rendements standards en nicotine et goudrons des cigarettes?

INTRODUCTION: Advertising information on cigarette package participate to the reduction of health risks from smoking. Impact on smokers has been poorly studied. This study intended to determine the smoker perception of nicotine and tar yields of cigarettes. METHODS: Consulting in an outpatient smoking cessation clinic, 171 smokers answered freely and spontaneously to a questionnaire evaluating their perception of nicotine and tar yields, cigarette consumption (number and brand), nicotine dependence. Simultaneously, biological tobacco markers were measured. RESULTS: The number of cigarettes, nicotine dependence and specific tobacco markers were not significantly different according to the cigarette type: "full savour", "light" or "ultra light". Women smoked less than men and 54% preferred "light" cigarettes versus 37% of men. These smokers were entering a tobacco cessation program, it was assumed they had lead a prior reflection about their smoking habits. Only 8% of them gave the correct values of nicotine and tar yields and 14% gave approximate values. Tar levels were highly underestimated. CONCLUSIONS: This study shows that smokers have actually no interest for nicotine and tar yields. As the new decree which modifies manufacture's obligation concerning the legal mentions, is applicable in January 2004 in France; our conclusion may change in the future.

A fluorescence microplate assay using yopro-1 to measure apoptosis: application to HL60 cells subjected to oxidative stress.

A new one-step labeling procedure using the membrane permeant fluorescent probe yopro-1 in association with fluorescence microtitration for the rapid determination of apoptosis is reported. Programmed cell death was induced by the pro-apoptotic agents etoposide and staurosporine, and measured in nonadherent HL60 cells and adherent phorbol 12-myristate 13-acetate (PMA)-treated HL60 cells. Cell viability was controlled by trypan blue exclusion and calcein-AM staining. To confirm results of fluorescence microplate assay, apoptosis was measured by flow cytometry analysis using the same fluorescent probe, and results showed corresponding data between both procedures. Development of apoptosis was confirmed by the presence of PARP (poly(ADP-ribose) polymerase cleavage and nuclear DAPI (4,6-diamidino-2-phenylindole) staining, two well-known methods used to investigate apoptosis. The fluorescence microplate assay was also applied to measure apoptosis in cells exposed to an oxidative stress induced by tert-butylhydroperoxide (t-BHP), and results confirmed the potential of the fluorescence microplate assay in measuring events of apoptosis, especially in adherent, cultured, living cells.

[Biomarkers of tobacco smoke exposure]. / Les marqueurs spécifiques du tabagisme.

Tobacco smoking is a major risk factor for cancer, cardiovascular diseases and respiratory illnesses. Smoking is increasing among children and adolescents with subsequent consequences on the health. Furthermore, maternal tobacco smoking during pregnancy adversely affects prenatal growth. Nicotine, the most important tobacco alkaloid, is responsible for maintaining tobacco addiction. According to a recent Circulaire de la direction générale de la santé, nicotine dependence should be determined through questionnaires and quantitative estimate of nicotine metabolites. Nicotine blood level fluctuates and urinary nicotine excretion is of short duration. Nicotine is intensively metabolized in the liver and oxidized into cotinine. Urinary measurement of cotinine appears to be highly related with the degree of intoxication and to allow the differentiation between non exposed and exposed non-smokers. In order to check the present application of nicotine metabolites measurement, a survey was conducted in 340 smoking cessation units. Forty percent physicians (n = 137) answered the survey. For 17% of them, the quantification of nicotine metabolites is included in their daily practise and for 79%, guidelines about cotinine measurement should be given in France. Sixty-seven biologists answered the survey. Recommendations for immunoassay and HPLC determination of cotinine should be given as reported by 66 and 44% of them respectively. Indeed, urinary cotinine measurement with high performance liquid chromatography is highly sensitive and specific. However, immunoassays are more convenient. These two approaches are presently under investigation in order to provide guidelines for optimal use in various clinical situations. Traditional measures for nicotine dependence are the number of cigarettes smoked per day, nicotine intake expressed as mg per day, Fagerstr m questionnaire, expired air carbon monoxide, thiocyanates and cotinine levels in biological fluids. Urinary cotinine measurement is the most useful for the follow-up of smoking cessation including adjustment of nicotine replacement therapy, especially after a clinical event or for the follow-up of smoking pregnant women. It allows the detection of passive smoke exposure in children who are hospitalized for recurrent respiratory illnesses.

[Physiopathology of iodine: current interest of its measurement in biological fluids]. / Physiopathologie de l'iode: intérêt actuel de son dosage en biologie clinique.

Iodine plays a central role in thyroid physiology, being both a major constituent of thyroid hormones and a regulator of thyroid gland functions. Iodine intakes considerably vary according to subjects. Inappropriate iodine intakes are worrying in term of public health regarding iodine deficiency (western world currently is not exempt) and regarding the frequency of iatrogen iodine overloads. Iodine disorders induce a biological and/or clinical expression of thyroid dysfunction, and in some cases can disclose pre-existent thyroid abnormalities. Determination of serum and urine iodine levels is an useful marker in the biological investigation of the thyroid function, can contribute to undertake an appropriate therapeutics and follow its efficacy.