In order to investigate the inhibitory effect of sodium dehydroacetate (DHA-Na) on the hepatocarcinogenicity of 4-dimethylaminoazobenzene (DAB), groups of 38 male Wistar rats (Sic) were fed diets containing 0.06% DAB, 0.1% DHA-Na and 0.06% DAB+0.1% DHA-Na (combination) throughout their life-time, and a similar group of animals was used as the control.
In order to investigate the inhibitory effect of sodium dehydroacetate (DHA-Na) on the hepatocarcinogenicity of 4-dimethylaminoazobenzene (DAB), groups of 38 male Wistar rats (Sic) were fed diets containing 0.06% DAB, 0.1% DHA-Na and 0.06% DAB + 0.1% DHA-Na (combination) throughout their life-time, and a similar group of animals was used as the control.
In the DHA-Na group there was essentially no change as compared with the control group. All animals from the DAB and combination groups died by the 15th and 16th months, and the deaths were all considered to be due to the development of hepatic tumors. Histopathologically, hepatic tumors observed in DAB and combination groups were hepatocellular carcinomas with hyperplasia or dilatation of the bile duct, and they frequently metastasized, mainly to the lung.
There was no difference between the DAB and combination groups in the histological findings of hepatic tumors. The combination group seemed to survive a little longer than the DAB group, but this was considered to be due not to DHA-Na, but to the difference of the actual amount of DAB intake between the two groups. This, together with the histological findings of hepatic tumors, suggests that DHA-Na did not exert an inhibitory effect on the hepatocarcinogenicity of DAB under the experimental conditions of this study.

View full abstract

The aim of the present work was to estimate the suppressive effects of glucose in the medium on the production of enterotoxin (ET) by strains of Staphylococcus aureus associated (10 strains) and not associated (200 strains) with food poisoning.
Glucose added to the medium had little influence on the growth, but inhibited ET production of 5 strains associated with food poisoning. ET-B and ET-C were more potently suppressed than ET-A and the amount of ET produced in the presence of 30% glucose was similar to that produced in rice flour gel plates, which resemble the incriminated foods.
Levels of ET production were decreased differently by glucose, α-methylglucoside (non-metabolizable glucose analogue), fructose, sucrose and glycerol, even at the same water activity (Aw). Our data might suggest that some factor other than glucose metabolism and Aw may be important in ET production.
In 30% glucose-containing medium, 10 strains associated with food poisoning produced more than 13ng/ml of ET and 47 strains out of 200 not associated with food poisoning also produced more than 13ng/ml. Their coagulase types were identified as II, III, VI or VII, known to be associated with food poisoning, except for one strain (IV).

View full abstract

The component patterns of chlordanes (total of 19 compounds) in human milk (n=12), cow's milk (n=10), dog adipose tissue (n=4), cat adipose tissue (n=6) and wild bird (2 species) were examined by mass spectrometry with selected ion monitoring. The component patterns in these samples were extremely different from those of aquatic biota described previously. In these higher animal samples, relatively high levels of residues of higher chlorine components (e. g. trans-, cis-nonachlor) and metabolites (oxychlordane, heptachlor epoxide) in relation to chlordanes were observed, though the component patterns varied in the different species of animal. High levels of residues of higher chlorine components were found in human milk, cat adipose tissue and wild bird samples, while the levels of metabolite residues were high in cow's milk and dog adipose tissue samples. The differences of component patterns may be due to species differences of metabolic activity.

View full abstract

A simple colorimetry procedure for the determination of dehydrogenase activity in shellfishes was developed. In the previous paper, we reported a colorimetry of dehydrogenase activity in oyster gill. Triphenyltetrazolium chloride (TTC) is reduced to triphenylformazan (TF) by dehydrogenase in oyster gill. The dehydrogenase activity in shellfish muscle is considerably lower than in oyster gill, and could not readily be measured. Therefore, a study was done on the activation of dehydrogenase.
When phosphate buffer (pH 7.4) was added to sodium chloride-TTC reagent (0.2% TTC-0.1% sodium succinate-3% sodium chloride), dehydrogenase activity in shellfish muscle was markedly increased. The dehydrogenase activity was also influenced by pH, osmotic pressure and others.
The composition of TTC reagent was 0.2% TTC-0.1% sodium succinate-2.84% disodium hydrogen phosphate-2.34% sodium chloride. A sample of shellfish muscle was sliced at about 1.5mm thickness, soaked in TTC reagent, incubated at 37° for 30min, and treated by the same procedure as in the case of oyster gill. Thus, dehydrogenase activity was activated sufficiently to be measured.
It was also possible to determine dehydrogenase activity in oyster gill using this TTC reagent.

View full abstract

Vibrio parahaemolyticus cells were treated with 0.1M acetate buffer (pH 5.0) containing 2% polypepton and 0.5 or 2% sodium chloride and then transferred into the growth medium, brain heart infusion broth with sodium-citrate and sodium-cholate. The following results were obtained. (1) At pH 8.0 0.1M sodium-citrate and 0.1% sodium-cholate co-operatively inhibited the growth of acid-injured cells which could grow in the control medium. (2) However, they did not inhibit the growth of non-treated or briefly acid-treated cells. (3) Sodium-glycocholate, sodium-taurocholate and bovine bile powder showed the same effect, with sodium citrate, as sodium-cholate. (4) Co-operative inhibition by sodium-citrate and sodium-cholate was dependent upon the pH of the medium. At pH 8.0 it was least, and increased at higher or lower pH. At pH 7.0, it caused a rapid decrease of viable cells.
These results might reflect one of the human defense mechanisms against food-poisoning bacteria in the intestine, involving the co-operation of citrate originating from foods and bile acid.

View full abstract

The effects of cadmium on intestinal absorption of copper, zinc and iron in rat everted intestine were investigated with and without L-cysteine in vitro. Intestinal absorption of copper was inhibited in the cadmium-administered intestine, and was not promoted by L-cysteine. Intestinal absorptions of zinc and iron were clearly inhibited in the cadmium-administered intestine, but were markedly promoted by L-cysteine.
The results of this experiment coincided with those of the previous in vivo experiment, in which copper and iron contents in organs were decreased by oral administration of cadmium as compared with those in controls, and the decrease in iron content was suppressed by the simultaneous administration of L-cysteine with cadmium. As regards copper content, the in vitro results did not coincide with the in vivo findings.

View full abstract

A sensitive and rapid method for the determination of sodium azide in wine by high performance liquid chromatography (HPLC) was developed.
Sodium azide in wine was converted into 3, 5-dinitrobenzoyl azide (DNBA) by reaction with 3, 5-dinitrobenzoyl chloride (DNBC). The reaction mixture was passed through a Seppak Florisil cartridge. The cartrigde was washed with water, then DNBA was eluted with a mixture of acetonitrile-0.05M citrate buffer solution, pH 3.6 (1:1). The eluate was injected onto a Finepak SIL C₁₈ column and eluted with a mixture of acetonitrile-water (1:1) as the mobile phase, and detected with a UV detector set at 254nm.
The recoveries of sodium azide added to white wine, red wine and sparkling wine were more than 94%. The detection limit of sodium azide in wine was 0.05μg/ml. The total analysis time was 40 minutes per sample.
By using this method, 52 commercial samples were analyzed. Sodium azide was not detected in any of the samples.

View full abstract

Paralytic shellfish poison (gonyautoxins, GTXs) has been tested for its effects on the peripheral neuromuscular system in frogs. The isotonic twitches of a frog sartorius muscle were recorded by applying electric stimuli alternately to the muscle (direct stimulation) and its motor nerve (indirect stimulation). The contractions elicited indirectly by stimulation of the motor nerve diminished and disappeared for 2-3 minutes after addition of GTXs (final concentration 0.2MU/ml), but the contractions elicited by direct stimulation did not. The wave of the compound action potential recorded from intact sciatic nerve was unchanged 120 minutes after exposure to GTXs (0.5MU/ml). When the desheathed sciatic nerve was treated with GTXs, the toxins produced a decreased in the amplitude of the wave within a few minutes. The end-plate potentials were observed from a frog sciatic nerve-satorius muscle preparation by using the separated box method. As the preparation was treated with GTXs (0.2MU/ml), the end-plate potential decreased gradually and finally disappeared. However, after the toxins were washed out of the preparation, the response usually recovered smoothly.

View full abstract

A method for the determination of zeranol and estradiol in beef by high performance liquid chromatography using an electrochemical detector (ECD-HPLC) is described. Zeranol and estradiol in beef were extracted with 80% methanol and re-extracted into dichloromethane. The crude extract was purified by column chromatography on piperidinohydroxypropyl Sephadex LH-20. Zeranol, estradiol and other anabolic drugs were clearly separated on a Shim-pack CLC-ODS column with 0.2% ammonium carbonate-acetonitrile (70:45) without any interference. The quantitation limits of zeranol and estradiol were 600pg and 450pg, respectively. The recovery rates of the two steroids added to beef were 88-97%. The proposed method was applied to the quantitation of zeranol and estradiol in commercial beef.

View full abstract

The effects of an extract of mushroom, Clitocybe clavipes, on ethanol metabolism were studied. An aqueous extract of the mushroom at a dose equivalent to 5g of fruit body/kg of body weight was injected intraperitoneally into male DBA/2Cr mice, then ethanol (4g/kg) was administered orally, and components and enzymes related to ethanol metabolism were assayed in the blood and liver.
The acetaldehyde level in the blood of the mushroom-ethanol-treated mice was twice that of the ethanol-treated mice at 30min after ethanol administration, while the ethanol level in the blood was approximately the same in both groups. Blood glucose level and the activities of serum transaminases in the mushroom-ethanol-treated mice were increased markedly at 1hr after administration when compared to the ethanol-treated mice.
The contents of free fatty acids and triglyceride in the serum of the mushroom-treated mice were increased significantly at 1hr after mushroom treatment when compared to the control (saline). In the liver of the mushroom-treated mice, the activity of aldehyde dehydrogenase was inhibited significantly at 1hr after mushroom treatment when compared to the control (saline).
These results indicate that the extract of the mushroom inhibits the activity of hepatic aldehyde dehydrogenase, which leads to an increase of acetaldehyde level in the blood, thus enhancing the toxicity of ethanol.

View full abstract

Groups of 5 male monkeys were fed 0, 0.01, 0.03, 0.1 and 0.3mg/kg/day of methylmercury chloride (as Hg) for 52 months. In the 0.3 and 0.1mg/kg/day groups, toxic signs including characteristic neurological ones appeared at 62 and 181 days (2.0 and 6.0 months) on average, respectively, during which period the total amounts of the test material ingested were 15.9 and 15.3mg/kg as Hg, respectively. Four animals from each group died or were sacrificed when they became moribund between the 57th and 70th days (1.9 and 2.3 months), and the 173rd and 242nd days (5.7 and 8.0 months), respectively.
All animals of both groups had Hg exceeding 100ppm in the hair at the time of onset of toxic signs. On the day of sacrifice, the Hg level of the whole blood was 12.37 and 8.04ppm, and that of the red blood cells was 26.45 and 17.26ppm on average for the groups given 0.3 and 0.1mg/kg/day, respectively. Histopathologically severe lesions of the cerebral cortex in the occipital lobe, particularly in the striate area, extending to the neighboring cortex were the most prominent feature. The lesions in the 0.1mg/kg/day group were more extensive and frequent, and more advanced in terms of tissue destruction than those in the 0.3mg/kg/day group, probably due to the protracted course of poisoning in the former group. No alteration was observed in the cerebellar cortex and white matter, spinal cord and peripheral nerves. Tubular degenerations predominant in the proximal tubules of the kidney were also ascribed to the feeding of the test material. Dose-related Hg accumulations were found in the central nervous system, in which the cerebrum showed the highest levels of Hg, nearly 100% as methyl Hg. Higher Hg accumulations which did not appear to be dose-related were present in the liver and kidney.
One animal from each of the 0.3 and 0.1mg/kg/day groups, to which the administration of the test material was suspended on the 151st and 541st days (5.0 and 17.8 months), respectively, survived the whole experimental period with complete or partial recovery from clinical signs. Histopathologically, however, extensive or localized cortical lesions persisted in these two animals. The high Hg levels in the hair at the time of suspension of administration of the test material decreased to the control level on the 644th and 1094th days (21.2 and 36.0 months), respectively. Although the Hg levels in various organs were very low, they were still higher, especially in the animal in the lower dose group, than those of the control, and the mercury contained was exclusively inorganic.
The animals of the 0.03 and 0.01mg/kg/day groups survived the experimental period without revealing any clinical signs, except a reduction in body weight gain in the former group at the later stage. The total amounts of the test material ingested in the groups were 39.6 and 13.2mg/kg as Hg, respectively. In the hematological examinations no specific change was observed. In the blood biochemical examinations, there was no significant change, except elevation of urea-N after 30 months in the 0.03mg/kg/day group. The Hg levels in the hair in the 2 groups decreased gradually after reaching the peaks of 154.6ppm on the 1094th day (36.0 months) and of 63.4ppm on the 917th day (30.1 months), respectively. Similarly the Hg levels in the blood decreased gradually after reaching the respective peaks of 1.422 and 0.474ppm at 30 months. No histopathological change was found in organs including the nervous system. Dose-related Hg accumulations, much lower than those in the groups given 0.3 and 0.1mg/kg/day, were found in various organs except the kidney. The ratio of methyl Hg to total Hg was fairly high in the cerebrum, liver, spleen, and muscle, whereas it was very low in the cerebellum and kidney, especially in the former.

View full abstract

There bleaching agents, sodium percarbonate, sodium perborate and sodium hypochlorite solution, were tested for acute oral toxicity in ddY mice and ocular irritation in rabbits.
The LD₅₀ values of (per os) sodium percarbonate were 2, 050mg/kg and 2, 200mg/kg, those of sodium perborate were 3, 600mg/kg and 3, 250mg/kg, and those of sodium hypochlorite were 6.8ml/kg and 5.8ml/kg, for male and female mice, respectively. These agents caused similar toxic signs, such as depression of spontaneous movement and irritative effects in the gastrointestinal tract.
As regards primary ocular irritation, more persistent and severe injury to the cornea and the conjuctiva was observed in the group without washing after administration of these agents. In particular, swelling of the cornea was observed in the group treated with sodium percarbonate. Such irritating effects, however, diminished after washing in the case of either sodium percarbonate or sodium perborate, but diminished only after early washing (4 seconds) in the case of sodium hypochlorite.

View full abstract

The effect of cooking, including washing in running water and heating, on the removal of toxicity from pufferfish liver was investigated. Twenty-one samples of poisonous liver with toxicity levels from 61MU/g to 1, 270MU/g were examined by a cooking method which is one of those used in the professional pufferfish stores in Oita prefecture. The toxicity was reduced to less than 5MU/g and the detoxication profiles during the cooking process were similar in all cases. Nevertheless, it still seems desirable to examine more toxic pufferfish liver than those used in this experiment, and other cooking methods.

View full abstract

The effect of growth of blue mussels on residual concentration of compounds apt to accumulate in marine products was examined. Shells from 3cm to 8cm long were sampled and the residual concentrations of a representative compound, PCB, in the peeled shellfish were determined. The PCB level on a wet basis in 8cm shell (15.0ppb on the average) was 1.7 times that in 3cm shell (9.0ppb on the average); the correlation between the shell length and the PCB concentration in the peeled shellfish was significant (r=0.78, P<0.001, N=34). Moreover, the correlation between the weight of stripped shellfish and the PCB level, and that between the weight of peeled shellfish and the length of shell were both significant (r=0.77, P<0.001; r=0.96, P<0.001; respectively).
These results may also be relevant to pollutants such as DDT, BHC analogs or organochlorine chemicals, which, like PCB, have large bioaccumulation factors between blue mussels and ambient seawater.

View full abstract