A physiologically based pharmacokinetic model for the prediction of the depletion of methyl-3-quinoxaline-2-carboxylic acid, the marker residue of olaquindox, in the edible tissues of pigs.

To estimate the consumer exposure to olaquindox (OLA) residues in porcine edible tissues, a physiologically based pharmacokinetic (PBPK) model for methyl-3-quinoxaline-2-carboxylic acid (MQCA), the marker residue of OLA, was developed in pigs based on the assumptions of the flow-limited distribution, hepatic metabolism, and renal excretion. The model included separate compartments corresponding to blood, muscle, liver, kidney, adipose, and an extra compartment representing the remaining carcass. Physiological parameters were determined from literatures. Plasma protein binding, partition coefficients, and renal clearance for MQCA were determined in in vitro and in vivo studies. The metabolic conversion of OLA to MQCA was assumed as a simple, one-step process, and an apparent first-order rate constant (k) was employed to describe this metabolic process. The PBPK model was optimized and validated with plasma and tissue data from literatures and our study. Sensitivity analysis and Monte Carlo simulation were also implemented to estimate the influence of model parameters on the goodness of fit. When compared with the observed data, the PBPK model underestimated the MQCA level in all compartments at the early time points, whereas gave excellent predictions of MQCA concentration in porcine edible tissues at later time points. The correlation coefficients between the predicted and observed values were over 0.88. The consistency between the model predictions and the real residues of OLA in pigs proved the good applicability of our model in food safety risk assessment.

[Analysis and efficiency-evaluation of case-finding among symptomatic suspects in rural area by smear microscopy].

216,307 suspects were discovered within the period from Oct. 1st, 1987 to Spt. 30th, 1988 in rural area of 26 counties. The suspect rate was demonstrated to be 2.2%; 182,917 persons accepted smear microscopy among suspects and the smear microscopy rate was 84.6%; 7,046 smear positive cases were detected and the smear positive rate was confirmed to be 3.95% among smear-accepted suspects. Smear microscopy among symptomatic suspects in rural area for infectious case-finding is recommended, because this method costs low, and is more effective and practical.

[Assessment on the epidemiological efficiency and treatment of smear positive pulmonary tuberculosis].

An epidemiological project for discovery and treatment of sputum (+) pulmonary tuberculous patients had been carried out during 1988-1990 in patients collected, this number was 3.1 times as the number obtained in the five year pre-application time. The annual mean value of proportion of smear (+) cases of newly registered patients was 63.53%, the average year rate of treatment coverage was 96.2%, the year complication rate of treatment was 89.2%, the sputum negative conversion rate was 87.0%, the cure rate in cohort analysis of management on chemotherapy was 85.8% in the period of 1988-1990. The annual reduction rate of prevalence rate of sputum (+) cases increased to 8.9% annually, but before this program (1979-1985), the percentage increased 1% per year. Thus, the epidemiological efficacy is significant.