Recent studies on the in vivo synthesis and degradation of matallothionein (MT) were reviewed mainly on the viewpoint of correlations between chemical forms of cadmium in the liver and kidneys and the toxicity of cadmium as follows. i) Analytical methods of MT and general cautions for the procedures which may affect the results of chemical forms. ii) Basal amounts of MT in the liver and kidneys, and their relations to the induction mechanisms. iii) Metal compositions which affect the degradation rate of MT. iv) Synthesis and degradation of MT in the liver after single injection of cadmium, zinc, copper, and endotoxin. v) Chemical forms of cadmium in the liver after repeated injections of cadmium. vi) Degradation and resynthesis of MT in the kidneys after single injection of MT and kidney injury. vii) Changes of chemical forms of cadmium in the kidneys during repeated injections of cadmium and its relation to transitory kidney injury. Transitory kidney injury after single injection of MT and during repeated injections of cadmium were explained as follows : Excess cadmium (than the capacity of basal MT biosynthesis) from the degraded MT for injection of MT or by the accumulation for repeated injections of cadmium cannot be sequestered as MT and causes kidney injury. However, the cadmium induces biosynthesis of MT (transcription of MT mRNA) and, therefore, the restoration occurs despite the constant amount of cadmium or consequtive loadings of cadmium. Persistent kidney injury was supposed to occur when the amount of accumulated cadmium exceeds the capacity of induced MT biosynthesis.

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To find a control index of activated sludge, dimethyl disulfide (DMDS) in the mixed liquor of aeration tank was tested. When the activated sludge was cultured at high load of BOD in synthetic wastewater (peptone, glucose), odorous sulfur compound was generated. It was identified as DMDS by gas chromatographmass spectrometer. The amount of DMDS in water could be quantitatively determined by the head space gas chromatographic method. When the condition of activated sludge became worse by increasing the load of BOD, DMDS was detected in the mixed liquor of aeration tank. When the condition of activated sludge was recovered by decreasing the load of BOD to be normal, DMDS was not detected. It was suggested that DMDS could be used as a useful control index for the estimation of the condition of activated sludge, because, DMDS was detected prior to the obvious changes of commonly used indices such as sludge volume index and BOD of effluent.

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In order to investigate the content of formaldehyde in fish-paste products, the determination of trace amounts of formaldehyde was studied. After the sample was steam-distilled to 1 l 2, 4-dinitrophenylhydrazone derived from formaldehyde was determined by gas chromatography. The recovery of the overall performance of this method was 80.0% for the fortification to kamaboko. The detection limit was 0.05 ppm of formaldehyde. The present method was successfully applied to the analysis of a trace amount of formaldehyde in commercial fish-paste products. The formaldehyde concentrations in tempura, kamaboko and chikuwa were 1.6-9.4 ppm, 1.6-3.6 ppm and 1.1-3.8 ppm, respectively. The sample having the highest concentration, 9.4 ppm, included a fragmentary cuttlefish.

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Losses of mercury and cadmium in aqueous solution during storage were studied under various conditions. When distilled water containing mercury at a concentration of 6-10 ngHg/ml was stored at 20°, the mercury level decreased to 70% of the initial level after 20 hr, but when stored at 0°or 4°the loss was small. The mercury lost from the distilled water was mostly due to volatilization and could not be recovered by washing the container with nitric acid. When river water filtered through a membrane filter (0.45 μm) was used as the solution, 95% of added mercury was found in the solution after storage for 7 days at 20°. The mercury which was not detected in the solution was mostly adsorbed on the wall of container and could be recovered by washing the container with nitric acid. Cadmium added to distilled water could be stored without a marked loss during storage for 24 hr even at 20°, while when added to river water free from suspended substances more than 95% of cadmium was retained in the solution after storage for 26 days at 20°.

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The uptake of labeled cadmium by isolated human erythrocytes was studied. The uptake of cadmium, usually studied at 37°, was determined by the increase of the radioactivity of ¹⁰⁹Cd in the erythrocytes. Cadmium was taken up slowly, and the amount was dependent on cadmium concentration in the medium in the range of 1.2 to 36.6 ppm. Starvation of erythrocytes, incubated at 37°, unaffected cadmium uptake, and cadmium uptake was not observed at 0°. The uptake of cadmium by ATP-loaded cells was lower than that by ATP-unloaded cells. The uptake of cadmium by erythrocytes does not seem to be closely coupled to energy production. Fifteen amino acids were tested for their capacity to influence the uptake of cadmium. Cysteine was powerfully inhibitory. Histidine stimulated the uptake of cadmium at levels of 5 and 10 ppm cadmium, but inhibited it at a level of 50 ppm cadmium. Histidine also enhanced the binding of cadmium to stroma at 10 ppm cadmium. Stimulation of cadmium uptake was recognized in imidazole but not in 1-methylimidazole. It was suggested that stimulation of cadmium uptake was possibly due to the enhanced transport of cadmium across the erythrocyte membrane in the form of cadmiumhistidine complex.

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Mercury contents of the tissues of tuna fish were determined. The ratio of methylmercury to total mercury in the edible meat was higher than that in the liver. Binding properties of the mercurials to the proteins in these tissues were investigated by gel filtration. Distribution pattern of mercury in the tissue proteins seems to depend on chemical structure of mercury compounds.

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The combined effects of polychlorinated biphenyls (PCB) and di-(2-ethylhexyl) phthalate (DEHP) on rat hepatic microsomal monooxygenases were investigated in 16 dose-groups consisting of 4 PCB-doses (0, 20, 67, and 200 mg/kg) and 4 DEHP-doses (0, 1, 3.3, and 10 g/kg). The additive or synergistic interaction between PCB and DEHP was estimated by analysis of variance by using orthogonal polynomials and by deviation from parallelism among dose-response curves. The combined effects of PCB and DEHP on liver weight and aminopyrine N-demethylase were additive and the effect on cytochrome P-450 was synergistic. Aniline hydroxylase was mainly induced only by PCB.

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The combined effect of cadmium on the hepatic microsomal monooxygenases was investigated by i.p. injection at a dose of 0.5 or 1.0 mg Cd/kg or by ingestion of diet containing 200 ppm Cd in the rats fed with normal or PCB (50 ppm) diet. The i.p. administration of cadmium reduced the amount of cytochromes P-450 and b₅, and the activities of aminopyrine N-demethylase and p-nitroanisole O-demethylase in normal diet group, but did not counteract the effect of PCB. The feeding of cadmium-containing diet enhanced the activity of covalently binding of bromobenzene with microsomal protein at 1 week and the inducing effect of PCB on aniline hydroxylase. However, cadmium feeding for 5 weeks counteracted the inducing effect of PCB on the covalently binding of bromobenzene. In conclusion, the effect of cadmium by oral administration was not so much on the hepatic microsomal monooxygenases.

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Thirteen commercial caramels and heated sucrose and glucose were examined for mutagenicity in the strains of S. typhimurium (TA100, TA98) with or without S-9 mix and for deoxyribonucleic acid (DNA) damaging effect in E. coli (Wild/pol A-, Wild/rec A-). Antibacterial activities of these compounds were also compared by using B. cereus, B. subtilis, B. bronchiseptica, E. coli, M. flavus, S. lutea and S. epidermidis strains. It was found that none of all these compounds were genetically active against S. typhimurium and E. coli, while furylfuramide (AF2) which was used as a positive control showed both mutagenic and DNA-damaging effects as expected. On the other hand, some heated sucroses and glucoses showed antibacterial effects on all bacterial strains used. The value of antibacterial activity against B. cereus was approximately one-tenth of that of benzoic acid.

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The aliphatic secondary and tertiary amines react with tropaeolin 00 to form chloroform soluble compounds. This reaction was applicable to a screening test for methamphetamine in the urines. The experimental procedure is as follows : 5 ml of the urine sample is added to a tropaeolin 00 solution. The mixture is allowed to stand for 2 minutes and then added 5 ml of chloroform. After shaking for 30 seconds, the chloroform layer is separated and dehydrated by anhydrous sodium sulfate, and methanol solution of sulfuric acid is added to the chloroform layer. The red or reddish-violet color of the chloroform layer suggests the presence of methamphetamine. The limit of identification for methamphetamine was 3 μg/ml of urine. No detectable interference was observed to identify methamphetamine in the presence of such drugs as barbiturates, analgesics, antacids, and vitamins.

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The effects of some fibers on the in vitro and in situ rat small intestinal absorption of cadmium were studied. The fibers, such as cellulose, pectin, glucomannan, lignin, sodium alginate (Na alginate), and sodium carboxymethylcellulose (Na CMC), tended to depress the intestinal absorption of cadmium. The depressive effects of lignin, Na alginate, and Na CMC on the absorption of cadmium were much greater than those of cellulose, pectin, and glucomannan. In addition, the effects of these fibers on the in vitro intestinal transport of cadmium were examined in the presence of L-cysteine or L-histidine, a stimulator of transport of the metal. Lignin and Na CMC depressed the stimulation of transport of cadmium by L-histidine.

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Effects of several chelating substances having sulfhydryl group on behavior of methylmercury in mouse tissues and on the release of methylmercury from the erythrocytes in vitro were investigated. The reciprocals of methylmercury concentration in the tissues of mice administered with the sulfhydryl compounds were well correlated with the amounts of methylmercury released in vitro from the erythrocytes in the presence of the respective substance.

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