Assessment of cassava toxicity in patients with tropical chronic pancreatitis.

BACKGROUND AND AIM: There have been conflicting reports on the role of cassava ingestion in tropical pancreatitis (TCP). In this study we aimed to estimate cyanogens detoxifying enzyme rhodanese, thiocyanate and sulfur containing amino acids in cassava consumer as well as cassava non-consumer TCP patients and healthy controls and compare the same. METHODS: Eighty-six TCP patients and 90 healthy controls were recruited. Serum rhodanese, thiocyanate, plasma amino acids, urinary inorganic sulfate/creatinine were measured. RESULTS: There was significant reduction in serum rhodanese activity in both cassava consumer- and non-consumer TCP patients as compared to controls but no significant difference between cassava consumer- and non-consumer TCP patients was observed. Serum thiocyanate was significantly lower in cassava consumer TCP patients as compared to cassava consumer controls but not significantly different from cassava non-consumer TCP patients. Plasma methionine, cysteine and urinary inorganic sulfate / creatinine ratio was significantly lower in both cassava consumer and non-consumer TCP patients as compared to controls but were comparable among cassava consumers and non-consumers. CONCLUSIONS: Significant reduction in rhodanese activity with concomitant decrease in sulfur containing amino acids and antioxidants such as glutathione suggests that TCP patients are at higher risk of defective detoxification of cyanogens. However there was no difference between cassava consumers and non-consumers. Low levels of sulfur amino acids may contribute to the development of pancreatitis.

Smoke intake among smokers is higher in lower socioeconomic groups.

OBJECTIVE: To analyse socioeconomic differences in serum thiocyanate concentrations among current smokers, and whether such differences persist after adjustment for the number of cigarettes smoked. SETTING: General population of six districts of the Czech Republic in 1992. PARTICIPANTS: 451 male and 282 female current smokers. MAIN OUTCOME MEASURE: Serum concentration of thiocyanate. RESULTS: There was a clear educational gradient in serum thiocyanate among male smokers; car ownership and crowding were not related to thiocyanate. Age adjusted mean concentrations in men with primary, vocational, secondary, and university education were 168.6, 158.2, 148.2, and 141.8 micromol/l, respectively (p for trend 0.032). Adjustment for the average daily number of cigarettes explained a part of this gradient. Socioeconomic differences in serum thiocyanate were not seen in women. CONCLUSION: The strong gradient in men suggests that smokers from lower socioeconomic groups have a preference for higher smoke intake and so may be more nicotine dependent. This finding, if confirmed, would have important implications for anti-smoking programmes.

Continuous trees and NEVADA simulation: a quadrature approach to modeling continuous random variables in decision analysis.

This paper introduces an improved technique for modeling risk and decision problems that have continuous random variables and probabilistic dependence. Variables are modeled with mixtures of four-parameter random variables, called "continuous trees." Functions of random variables are calculated using gaussian quadrature in a manner called "Nevada simulation" (NumErical Integration of Variance And probabilistic Dependence Analyzer). This technique is compared with traditional decision-tree modeling in terms of analytic technique, solution-time complexity, and accuracy. Nevada simulation takes advantage of the probabilistic independence in a decision problem while allowing for probabilistic dependence to achieve polynomial computational-time complexity for many decision problems. It improves on the accuracy of traditional decision trees by employing larger approximations than traditional decision analysis. It improves on traditional decision analysis by modeling continuous variables with continuous, rather than discrete, distributions. A Bayesian analysis using a mixed discrete-continuous probability distribution for cigarette smoking rate is presented.

Assessment of tobacco-exposure during pregnancy; behavioural and biochemical changes.

Smoking-behavior during pregnancy and the reliability of an interview were prospectively investigated. The tobacco-exposure was assessed a) by an intake interview b) by a smoking diary and c) by maternal thiocyanate and carboxy-hemoglobin concentrations. Of the 115 nulliparous women, 66 smoked (57.4%). Seventeen women (25.8%) quit and 39 women (59.1%) reduced smoking. Directly after intake, in the first week of the diary, significantly more cigarettes were smoked than stated during the intake interview. According to the diaries, the number of cigarettes increased during the first half of pregnancy. In the 24th week significantly more cigarettes were smoked than in the first week after intake. Also a significant increase of thiocyanate between the measurements at intake and in the 24th of amenorrhea was found. The maternal carboxy-hemoglobin levels did not significantly change during pregnancy. Investigators should be aware of changes in smoking behavior during pregnancy and the potential bias of self reported smoking behavior at the beginning of pregnancy. The tobacco-exposure should be assessed (anamnestic or biochemical) several times during pregnancy, anyway it should include the second half of pregnancy.

Assessment of passive and transplacental exposure to tobacco smoke.

Although tobacco smoke has been shown to be highly genotoxic in various experimental systems, most nonmolecular methods designed to assess exposure to mutagens are too insensitive to detect passive exposure to tobacco smoke. Biochemical markers of intake--cotinine and thiocyanates in body fluids--were shown to be elevated after occupational, passive or transplacental exposure to tobacco smoke, while no response was seen in the frequency of sister chromatid exchanges (SCE) in cultured blood lymphocytes. After occupational exposure to environmental tobacco smoke, the intake marker levels are generally less than 5% of the levels found in active smokers, while cord blood levels (representing fetal exposure) are at about the same level as in the mothers at the time of delivery.

The effect of antismoking intervention during pregnancy: an assessment of interactions with maternal characteristics.

In a previous experimental study, which included 935 pregnant smokers recruited from private obstetric practices located in a large metropolitan area and from one hospital obstetric clinic, a 92-g difference was found between infants born to women who had antismoking intervention and those born to women in a control group. The current report further examines the effect of intervention on both smoking cessation during pregnancy and birth weight. Specific attention is given to interactions between intervention and maternal characteristics. These maternal characteristics were determined at the time of first prenatal care. A stepwise regression analysis was performed to assess 1) the association of each maternal variable with smoking cessation and birth weight; 2) the effect of intervention on these outcomes after adjusting for the maternal variable; and 3) the interaction effect between intervention and the maternal variable. The effect of intervention on smoking cessation was found to be significantly greater for women who experienced problems early in pregnancy, such as high blood pressure and urinary tract infection. The beneficial effect of intervention on birth weight decreased with age and number of previous low birth weight infants but increased with previous fetal loss. There is some evidence to suggest that the effect of intervention on birth weight is also dependent on the amount of smoking prior to intervention.