Akiyoshi Nishikawa

Inhibitory effects of chlorogenic acid, reserpine, polyprenoic acid (E-5166), or coffee on hepatocarcinogenesis in rats and hamsters.

Four different experiments were performed in order to examine the modifying effects of chlorogenic acid (CA), reserpine, polyprenoic acid (E-5166), and coffee on chemical carcinogenesis in rats or hamsters. Experiment 1: The numbers of hyperplastic liver cell foci and the incidence of colon tumors in male and female Syrian golden hamsters given a single intravenous injection of methylazoxymethanol (MAM) acetate and then fed the diet containing 0.025% CA for 24 wk were significantly lower than those of hamsters given MAM acetate alone. Experiment 2: The incidence of altered hepatocellular foci in female ACI/N rats given N-2-fluorenylacetamide (FAA, 0.02% in diet) for 10 wk and reserpine (weekly subcutaneous injections, 1 microgram/g body weight) during or after (17 wk) FAA exposure was significantly lower than that of rats given FAA alone. Experiment 3: The number of hepatocellular foci in male ACI/N rats given 0.02% FAA diet for 13 wk and E-5166 by gavage (40 mg/kg body weight, 3 times/wk) for 16 wk after the end of FAA exposure was significantly smaller than that in rats given FAA diet alone. Experiment 4: Incidences of liver tumors and hepatocellular foci of rats given concurrent dietary administration of aminopyrine (0.01%) and sodium nitrite (0.1%) and coffee solution as a drinking water for 630 da were significantly lower than those of rats given aminopyrine and sodium nitrite. Thus, the tested compounds had inhibitory effects on chemical carcinogenesis in liver or colon.

Inhibitory effects of non-steroidal anti-inflammatory drugs, piroxicam and indomethacin on 4-nitroquinoline 1-oxide-induced tongue carcinogenesis in male ACIN rats

The effects of the non-steroidal anti-inflammatory drugs (NSAIDs), piroxicam and indomethacin on 4-nitroquinoline 1-oxide-(4-NQO)-induced tongue carcinogenesis in male ACI/N rats were examined. Rats were given 4-NQO (10 ppm) in the drinking water for 12 weeks and followed by either diet containing 150 ppm piroxicam or the drinking water containing 10 ppm indomethacin for 24 weeks. The incidence of tongue neoplasms (squamous cell papilloma and carcinoma) in rats given 4-NQO plus piroxicam (4/13, 31%) and those given 4-NQO plus indomethacin (3/13, 23%) were significantly lower than that of animals given 4-NQO alone (12/17, 71%) (P less than 0.05 and P less than 0.005). Rats given piroxicam or indomethacin alone had no neoplasms in the tongue. Thus, piroxicam and indomethacin significantly inhibited the development of tongue neoplasms in male ACI/N rats.

Genotoxicity of a variety of hydrazine derivatives in the hepatocyte primary culture/DNA repair test using rat and mouse hepatocytes

The genotoxicity of a variety of hydrazine derivatives was examined in the DNA‐repair test on rat or mouse hepatocytes. Out of 32 hydrazine derivatives, 6 chemicals, i.e., N‐acetyl‐4‐(hydroxymethyl)phenylhydrazine, 1,2‐dimethylhydrazine ‐ 2HCl, 1‐hydrazinophthalazine ‐ HCl, methylhydrazine‐sulfate, p, p′‐oxybisbenzene disulfonylhydrazide and phenylhydrazine‐HCl, elicited positive DNA repair responses in the test on rat hepatocytes. In the test on mouse hepatocytes, 4 more hydrazine derivatives, i.e., 1,1‐dimethylhydrazine, hydrazine hydrate, hydrazine sulfate and 2‐methyl‐4‐chlorophenoxyacetic acid hydrazide‐HCl also generated positive responses, in addition to the 6 positive compounds in the rat assay. These results suggest that mouse hepatocytes are more susceptible to the genotoxicity of hydrazine derivatives, and that the species differences in genotoxicity appear to he in agreement with the in vivo carcinogenicity of these agents.

A 13-week repeated dose study of three 3-monochloropropane-1,2-diol fatty acid esters in F344 rats

Abstract3-monochloropropane-1,2-diol (3-MCPD), a rat renal and testicular carcinogen, has been reported to occur in various foods and food ingredients as free or esterified forms. Since reports about toxicity of 3-MCPD esters are limited, we conducted a 13-week rat subchronic toxicity study of 3-MCPD esters (palmitate diester: CDP, palmitate monoester: CMP, oleate diester: CDO). We administered a carcinogenic dose (3.6xa0×xa010−4xa0mol/kgxa0B.W./day) of 3-MCPD or these esters at equimolar concentrations and two 1/4 lower doses by gavage with olive oil as a vehicle five times a week for 13xa0weeks to F344 male and female rats. As a result, five out of ten 3-MCPD-treated females died from acute renal tubular necrosis, but none of the ester-treated rats. Decreased HGB was observed in all high-dose 3-MCPD fatty acid ester-treated rats, except CDO-treated males. The absolute and relative kidney weights were significantly increased in the ester-treated rats at medium and high doses. Relative liver weights were significantly increased in the esters-treated rat at high dose, except for CMP females. Significant increase in apoptotic epithelial cells in the initial segment of the epididymis of high-dose ester-treated males was also observed. The results suggested that although acute renal toxicity was lower than 3-MCPD, these three 3-MCPD fatty acid esters have the potential to exert subchronic toxicity to the rat kidneys and epididymis, to a similar degree as 3-MCPD under the present conditions. NOAELs (no-observed-adverse-effect levels) of CDP, CMP and CDO were suggested to be 14, 8 and 15xa0mg/kgxa0B.W./day, respectively.

Enhancing Effect of Ethanol on Aflatoxin B1‐induced Hepatocarcinogenesis in Male ACI/N Rats

The modifying effect of ethanol (EtOH) on aflatoxin B1 (AFB1)‐induced hepatocarcinogenesis was examined in male ACI/N rats by chronic treatment at the post‐initiation phase. Rats received an ip injection of AFB1 (1.5 mg/kg) twice a week for 10 weeks (a total of 20 doses). Following a week of acclimation, they were given 10% EtOH as drinking water for 56 weeks. The effect of EtOH on the hepatocarcinogenesis was evaluated in terms of the incidence of altered hepatocellular foci and neoplasms at the end of the experiment. Exposure to AFB1 alone induced a substantial number of altered foci (6.98 iron‐excluding foci/cm2) in rats. The number of altered liver cell foci in rats receiving AFB1 followed by EtOH was significantly increased (26.39 iron‐excluding foci/cm2). In the rats given EtOH after AFB1 the total area and mean diameter of both iron‐excluding foci and altered foci identified in hematoxylin and eosin‐stained sections were significantly higher than in the rats exposed to AFB1 alone. The incidence of liver cell tumors of the group given AFB, and EtOH (3/15, 20%) was higher than that of the group treated with AFB1 alone (0/14, 0%). Treatment with EtOH alone for 56 weeks did not induce either. These results indicate an enhancing effect of EtOH on AFB1‐induced hepatocarcinogenesis when it is given in the promotion phase.

Absence of in vivo genotoxicity of 3-monochloropropane-1,2-diol and associated fatty acid esters in a 4-week comprehensive toxicity study using F344 gpt delta rats

3-Monochloropropane-1,2-diol (3-MCPD) is regarded as a rat renal and testicular carcinogen and has been classified as a possible human carcinogen (group 2B) by International Agency for Research on Cancer. This is potentially of great importance given that esters of this compound have recently found to be generated in many foods and food ingredients as a result of food processing. There have been a few reports about their toxicity, although we have recently found that the toxicity profile of 3-MCPD esters was similar to that of 3-MCPD in a rat 13-week repeated dose study, except for the acute renal toxicity seen in 3-MCPD-treated females. In the present study, to examine in vivo genotoxicity we administered equimolar doses of 3-MCPD or 3-MCPD fatty acid esters (palmitate diester, palmitate monoester and oleate diester) to 6-week-old male F344 gpt delta rats carrying a reporter transgene for 4 weeks by intragastric administration. In vivo micronucleus, Pig-a mutation and gpt assays were performed, as well as investigations of major toxicological parameters including histopathological features. As one result, the relative kidney weights of the 3-MCPD and all three ester groups were significantly increased compared with the vehicle control group. However, the frequency of micronucleated reticulocytes and Pig-a mutant red blood cells did not differ among groups. Moreover, no changes were observed in mutant frequencies of gpt and red/gam (Spi(-)) genes in the kidney and the testis of 3-MCPD and 3-MCPD-fatty-acid-esters-treated rats. In histopathological analyses, no treatment related changes were observed, except for decrease of eosinophilic bodies in the kidneys of all treated groups. These results suggest that 3-MCPD and its fatty acid esters are not in vivo genotoxins, although they may exert renal toxicity.

Fine-needle aspiration cytology of xanthogranulomatous pyelonephritis

Fine-needle aspiration cytology of xanthogranulomatous pyelonephritis in a fifty-seven-year-old Japanese woman is reported. Foamy cells and cells showing a gland-like pattern originating from degenerative renal tubules were found in the aspirated smears. Multinucleated giant cells and cells with pale yellowish cytoplasm were seen in the imprint smears at operation. These findings were diagnostic for xanthogranulomatous pyelonephritis. The cytologic diagnostic differences among xanthogranulomatous pyelonephritis, well-differentiated renal cell carcinoma, and renal oncocytoma are also described.

Malignant mesenchymoma of the heart

A case of a rare primary cardiac tumor in a 46‐year‐old woman is described. The tumor arose from the left atrium and was histologically composed of multiple mesenchymal elements of fibrosarcoma, rhabdomyosarcoma, chondrosarcoma, myxosarcoma, and liposarcoma. Metastasis of this tumor occurred in the left femur, lung, and hilar lymph nodes after the second heart operation. Histogenesis of malignant mesenchyoma was considered with a survey of the literature.

Orally administered glycidol and its fatty acid esters as well as 3-MCPD fatty acid esters are metabolized to 3-MCPD in the F344 rat.

IARC has classified glycidol and 3-monochloropropane-1,2-diol (3-MCPD) as group 2A and 2B, respectively. Their esters are generated in foodstuffs during processing and there are concerns that they may be hydrolyzed to the carcinogenic forms in vivo. Thus, we conducted two studies. In the first, we administered glycidol and 3-MCPD and associated esters (glycidol oleate: GO, glycidol linoleate: GL, 3-MCPD dipalmitate: CDP, 3-MCPD monopalmitate: CMP, 3-MCPD dioleate: CDO) to male F344 rats by single oral gavage. After 30 min, 3-MCPD was detected in serum from all groups. Glycidol was detected in serum from the rats given glycidol or GL and CDP and CDO in serum from rats given these compounds. In the second, we examined if metabolism occurs on simple reaction with rat intestinal contents (gastric, duodenal and cecal contents) from male F344 gpt delta rats. Newly produced 3-MCPD was detected in all gut contents incubated with the three 3-MCPD fatty acid esters and in gastric and duodenal contents incubated with glycidol and in duodenal and cecal contents incubated with GO. Although our observation was performed at 1 time point, the results showed that not only 3-MCPD esters but also glycidol and glycidol esters are metabolized into 3-MCPD in the rat.

Absence of initiating activity by quercetin in the rat liver

Initiating activity of quercetin was tested in rats which were treated with partial hepatectomy and given a liver cancer promoter, phenobarbital. A few intestinal neoplasms were seen but without significant difference in incidence from those in the quercetin-untreated group. Moreover, neither neoplastic nor preneoplastic liver changes were detected in quercetin-treated groups. With hepatocyte primary culture/DNA repair test, quercetin did not produce genotoxicity. The results show that quercetin has no initiating or genotoxic activities in the rat liver.