Residues of the coccidiostat clopidol (3, 5-dichloro-2, 6-dimethyl-4-pyridinol) in commercial chicken tissues were investigated in Sapporo city by means of ECD-gas chromatography. The tissues were extracted with methanol and the extracts were filtered and cleaned up on alumina and anion exchange resin columns. The eluates were treated with diazomethane to obtain the methyl ether of clopidol, which was detected by ECD-gas chromatography. The compounds were detected in commercial chicken tissues at levels of 0.04 to 1.9ppm in 12 out of 31 samples. The detected substance was identified as methyl-clopidol (3, 5-dichloro-4-methoxy-2, 6-lutidine) by mass chromatography. Further studies seem desirable on residual clopidol in livestock products.
The metabolism of 14C-aflatoxin B1 (Af. B1) in the chick embryo was studied. When inoculated into air cells, the embryos, egg membranes, other parts of the eggs and the expired carbon dioxide during a 1 hour period contained 8.0, 15.0, 76.0 and 1.0% of the total detected radio-activity, respectively. In the case of yolk sac inoculation, the embryos, other parts of the eggs and the expired carbon dioxide during a 1 hour period contained 3.4, 96.4 and 0.2% of the total detected counts, respectively. At equal doses of (14C)-Af. B1 into the air cell and yolk sac of eggs, the embryos incorporated 14C in a ratio of 2.5:1, which is similar to the ratio of LD50 values (air cell inoculation=0.41μg/egg; yolk sac inoculation=0.89μg/egg) by the two inoculation routes. The homogenate of embryos inoculated with Af. B1 was partitioned into chloroform and methanol-water. As the time after inoculation increased, methanol-water-soluble metabolites from Af. B1 increased and chloroform-soluble ones decreased. Af. M1 was the principal metabolite among the chloroform-soluble substances.
We examined by statistical analysis the possible role of indigenous oral bacteria in nitrite formation in human saliva. In 13 volunteers' saliva, a relatively high positive correlation was observed between the nitrate-reducing activity of the saliva and the number of nitrate-reducing bacteria. However, there was no significant correlation between the nitrate-reducing activity of saliva and the concentration of salivary nitrite. The geometric mean rates (95% confidence limits of the mean) of nitrate reduction and of nitrite production of the saliva in vitro were only 0.94 (0.48-1.85)μg/ml/min and 0.37 (0.20-0.67)μg/ml/min, respectively. The estimated nitrate-reducing activity of indigenous oral bacteria in saliva thus does not support the hypothesis that the nitratereducing bacteria play an essential role in the formation of nitrite in the mouth.
Recent investigations have shown that sodium cyclamate (CHS-Na) can be metabolized to cyclohexylamine (CHA) by certain species of intestinal bacteria inhabiting the gut of animals and man, but the CHS-Na converting bacteria were not clearly identified. Entero-bacterial formation of CHA in rabbits and guinea pigs was investigated chemically in animals surgically intubated into the cecum with the feces of CHS-Na converter monkeys under long-term feeding with CHS-Na. To obtain CHS-Na converting bacteria in vivo and in vitro, microbiological studies were carried out on the intestinal contents and feces of normal and converter animals. Feeding experiments were conducted in two diet groups: rabbits and guinea pigs were given appropriate standard commercial diet or the monkey diet alone. 1) Normal rabbits and guinea pigs that were given 0.5g of converter monkey feces intragastrically became converter animals in 1 to 3 days under continuous feeding with CHS-Na. 2) CHS-Na conversion seemed to be enhanced in rabbits and guinea pigs fed the commercial monkey diet alone instead of appropriate commercial diets. 3) In rabbits and guinea pigs that had switched from normal to converter status, no significant changes of fecal and cecal microflora were obserbed among Bifidobacterium, Peptostreptococcus, Veillonella, Lactobacillus, Streptococcus, Enterobacteriaceae, Staphylococcus, molds and yeasts, but slight changes were found in Clostridium sp., Propionibacteriaceae and Bacteroidaceae. 4) CHS-Na conversion ability was determined chemically and microbiologically in mass cultures of these intestinal flora. In vitro experiments suggested that some specific bacteria belonging Clostridium sp., Propionibacteriaceae and Bacteroidaceae may have CHS-Na conversion activity. Taxonomical studies with these strains at the species level are in progress.
Benzo (k) fluoranthene (BkF) is a polycyclic aromatic hydrocarbon which is of interest because its fluorescence spectra bear a close resemblance to those of benzo (a) pyrene (BaP). However, there have been few reports so far as to its actual content in foods. Our previous report described a method to separate BaP from BkF when the two hydrocarbons coexist in the final solution. In this work, the presence and content of BkF were explored in 48 samples of foods, including meat, fish, fruit, butter, etc. BkF was detected at levels of 0.01 to 29.9ppb in 30 out of 48 samples, and the BaP content determined simultaneously was 0.06 to 25.6ppb in 33 out of 48 samples. The regression line of BkF (Y) on BaP (X) was: Y=0.73X-0.48 and the correlation coefficient was 0.83.
A simple procedure for sensitive determination of the lytic activity of lysozyme is presented. This procedure was carried out turbidimetrically at a higher temperature (60°C) and for a longer time (60min) than in the conventional method. In order to stimulate the lytic activity of lysozyme, small amounts of nonionic surfactant and NaCl were added to M/15 phosphate buffer, pH 6.2. With this procedure, it was possible to determine the lytic activity of hen egg white lysozyme at a concentration of 0-15ng/ml of reaction solution. It was also possible to determine lysozyme added at low concentration to some kinds of foods which exhibit strong turbidity.