Considering the results of our previous experiment, another animal experiment using rats was carried out to elucidate the interaction of Cd and Zn on the ac-cumulation of some metals in tissues and to clarify the protective effects of Zn on the ceronic toxicity of Cd. The animals were divided into 4 groups. The diet for Group I was added 50 ppm of Cd, that for Group II was added 50 ppm of Zn and that for Group III was added 50 ppm of Cd and 50 ppm of Zn. Group IV was the control group. One-half of the animals in each group were killed after 14 weeks of exposure and the other half after 28 weeks of exposure. In both cases, several metals in the tissues were analyzed. Conclusions derived from the results of this experiment are as follows: 1) Cd accumulation in the kidney and the liver is not influenced by the simultaneous administration of Zn, 2) Zn increases in the liver by Cd administration, 3) Cd intake also enhances Cu level in the tissues, 4) Zn prevents anemia caused by Cd exposure, 5) no differences are found in Ca concen-trations in the femur among the groups, and 6) significant histopathological changes of the kidneys are not observed among the exposed animals.
The present investigation reports on the topography of few enzymes viz-alkaline phosphatase, acid phosphatase, 5-nucleotidase and lipase in the kidney of rat, Rattus rattus albino after individual and combined treatments with molybdenum and copper. Molybdenum intake altered enzyme activities whereas total inhibition was caused by copper though lipase remained un-inhibited. Comparison of controls with the combined effects, revealed no appreciable difference in the topography of these en-zymes. Reversible dysenzymia thus observed points towards the conditioned metal ion antagonism and rapair in cellular membranes. Several hypothesises for their differential biochemical behaviour, cause & significance in enzymological patterns have been considered. Reversible dysenzymia has been explained on the basis that copper becomes unavailable through interaction with molybdate to form either cupric molybdate or copper thiomolybdate which is ultimately excreted.
An apparent difference in trichloroethylene metabolism was observed between animals; human, rabbit and rat exposed to trichloroethylene. Rats metabolized the substance most rapidly, while metabolism in human proceeded at the slowest rate. The ratio of trichloroethanol to trichloroacetic acid, both the main metabolites in urine, was the largest in rabbit and the smallest in human. There was not observed a significant sex difference in trichloroethylene meta-bolism in rat, while there seemed to exist the age difference in trichloroethylene metabolism in rat though not significant. The metabolic pathway of trichloroethylene in rats did not alter with the size of trichloroethylene intraperitoneally injected at dose levels of 22-368 mg/kg. This might suggest to establish the maximum allowable concentration of trichloroethylene in the working environment from the viewpoints other than the altered metabolic pathway of trichloroethylene with the difference dose level. It was probably due to the physical mechanism that the ratio of total trichloro-compounds in urine to the dose of trichloroethylene decreased with the increase of dose.
Metabolism of trichloroethylene with special reference to the metabolic pathway and rate were studied; trichloroethylene metabolites in urine were determined in rats, which were intraperitoneally administered with trichloroethylene or its metab-olites such as chloral hydrate, trichloroacetic acid or trichloroethanol. One-third of trichloroethylene administered was found to be metabolized to trichloroethanol via chloral hydrate. A minor metabolite, trichloroacetic acid, was suggested to be produced via chloral hydrate or via trichloroethanol. Metabolic rate from trichloroethylene to chloral hydrate was relatively slow, while the biotransformations of chloral hydrate to trichloroethanol and to trichloro-acetic acid were very rapid. The metabolic rate of trichloroethanol to trichloroacetic acid was remarkably slow. Metabolism of trichloroethylene in rabbits was demonstrated as well.
The frequencies of sister chromatid exchanges (SCE) and chromosome aberra-tions were examined in cultured Chinese hamster cells (Don) exposed to two sorts of fume particles collected from different procedures of stainless steel welding. It was confirmed that the frequencies of SCE and chromosome aberrations in the cells treated with these fume particles increased with increasing fume doses within the range of the fume concentration tested. The fume partticles collected from manual metal arc (MMA) welding were more powerful than those from metal inert gas (MIG) welding. In order to cause the same increase in SCE frequency the fume particles from MIG welding needed to be about 100 times as much as those from MMA welding. The fume particles from MMA welding showed a higher so-lubility of Cr than those from MIG welding. The amount of dissolved Cr from the former was about 60 times as much as that from the latter when culture medium was used as a solvent. Small amounts of Mn, Ni, Fe and Mg were also detected in the supernatants of both fume suspensions. There were no significant differences in the amounts of these metals as was found with Cr when comparing MMA weld-ing with MIG welding. The frequencies of SCE and chromosome aberrations were also increased by the addition of the supernatants of these suspensions. From these results, it was assumed that dissolved hexavalent Cr may be involved in the cytogenetic effect of the fume particles from stainless steel welding.
Using a signal indicator, an integer calculation with two figures was loaded to male college students as a mental task. Effects of several factors on physiological and psychological parameters were investigated by experimental design method. The factors studied here were (A) task load (40 and 80% of maximum speed of each subject), (B) sleeping hours in the previous night (8 and 0 hr), (C) working hours (20 and 60 min) and (D) rest hours after task (60 and 20 min). The physiological parameters were pulse rate, axillary temperature, blood pressure, plasma volume and plasma protein. The psychological parameters were rating value of hardness of work and error answer ratio (%) in the calculation. During the task period, error answer ratio, rating value, pulse rate and axil-lary temperature were statistically significant for the factor of task load (A). The severe task load provoked more intense effect on those parameters than the weak load. Sleep deprivation in the previous night caused change of pulse rate and plasma protein in the rest time. Interactions between task load and sleeping hours (A×B) and working hours (A×C) were significant on the values only concerning the blood such as hemoglobin concentration and total protein. These results might be applied for evaluation of labour environmental condi-tions.