Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 17). Testicular toxicity of E7010, a sulfonamide tubulin polymerization inhibitor

E7010 (N-[2-[(4-hydroxyphenyl)amino]-3-pyridinyl]-4-methoxybenzenesulfonamide), a sulfonamide antitumor agent that inhibits tubulin polymerization, was orally administered to male Slc:SD rats at doses of 50 and 75 mg/kg once a day for 2 weeks. E7010 at a dose of 75 mg/kg induced severe testicular lesions characterized by marked decrease and/or loss of seminiferous epithelial cells, which sometimes resulted in tubules with only Sertoli cells. In the 50 mg/kg group, alteration of germ cells was evident at various stages of spermatogenesis, and apoptotic figures of meiotic spermatocytes at stage XIV were frequently observed. Single dose treatment of 50 mg/kg was also performed and was revealed a decrease of round spermatids in stage VII at necropsy after 1 week. Thus the target cells were considered to be meiotic spermatocytes at stage XIV. The present study indicates that 2-weeks repeated dosing is sufficient to detect the testicular toxicity of E7010.

Protection from drug-induced hepatocellular changes by pretreatment with conjugating enzyme inhibitors in rats

The present paper describes the role of conjugating enzymes in the development of hepatotoxicity after administration of repeated doses of a novel monoamine oxidase type-A (MAO-A) inhibitor, (5R)-3-[2-(( 1S)-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5-methoxymethyl-2-oxazolidinone (E2011). The effects of pretreatment with three kinds of conjugating enzyme inhibitors on hepatic lesions induced by E2011 were evaluated in female Sprague-Dawley rats. The inhibitors used were 2,6-dichloro-4-nitrophenol (DCNP; inhibitor of sulfotransferase (ST)), pentachlorophenol (PCP; inhibitor of both ST and acetyltransferase (AT)) or ranitidine (inhibitor of UDP-glucuronosyltransferase (UDP-GT)). Two weeks treatment of E2011 alone at an oral dosage of 150 mg/kg induced hepatocellular changes characterized by nuclear enlargement. Daily pretreatment with DCNP (10 mg/kg, i.p.) enhanced the E2011-induced hepatocellular changes accompanied by single cell necrosis. On the other hand, the hepatotoxicity was clearly diminished by PCP (5 mg/kg, i.p.). Ranitidine pretreatment had no effect. Protection by PCP was attributed to the inhibitory effects of AT in addition to ST; it was considered that the hepatocellular changes caused by E2011 were largely dependent on the formation of acetyl conjugate(s).

A staining procedure for micronucleus test using new methylene blue and acridine orange: specimens that are supravitally stained with possible long-term storage

The micronucleus test has been widely used as an in vivo cytogenetic test. It employs two different kinds of supravital staining methods which use either new methylene blue (N) and Giemsa (G) or acridine orange (AO). We have developed a new staining procedure for the preparation of specimens supravitally stained with possible long-term storage, using both N and AO. This N/AO-staining method involves three steps; (1) combination of the target tissue or target cells with an equivalent volume of 0.5% solution of new methylene blue (N-staining step), (2) immediate smear of the mixture, followed by treatment with methanol for 10 min for fixation and removal of N and drying (referred to as fixed-decolorized specimens), and (3) staining with 0.007% solution of AO for 3 min, followed by washing with Sörensen's buffer (pH 6.8) and covering of specimens before observation (AO-staining step). To examine whether the N/AO-staining method is useful for the micronucleus test, comparisons were made between N-, N/AO-, and AO-stained specimens prepared supravitally from peripheral blood of rats with and without treatment of cyclophosphamide. The results indicate that N/AO-stained specimens can be supravitally observed after long-term storage with the same coloration and comparable frequencies of micronucleated reticulocytes with a positive response as AO-stained specimens, if the staining process is temporarily stopped before AO-staining (as fixed-decolorized specimens), or if the AO-staining step is repeated. The results also showed that separated reticulocyte types are supravitally stained in a similar fashion to N-stained specimens but not to AO-stained specimens, indicative of the preservation of the supravital feature of N-staining. Taken together these results suggest that the N/AO-staining procedure could offer an additional useful staining tool for the micronucleus test.

Inhibition of sulfotransferase affecting in vivo genotoxicity and DNA adducts induced by safrole in rat liver

The effect of pretreatment with pentachlorophenol (PCP), a known inhibitor of sulfotransferases, on the induction of chromosomal aberrations, sister chromatid exchanges (SCEs), replicative DNA synthesis (RDS), and the formation of DNA adducts was studied in the liver of rats treated with safrole (1-allyl-3,4-methylenedioxy-benzene). Rats were given a single oral dose (1,000 mg/kg body weight) or 5 repeated doses (500 mg/kg body weight) of safrole, with or without intraperitoneal pretreatment with PCP (10 mg/kg body weight). Hepatocytes were isolated 24 hr after administration of safrole and allowed to proliferate in Williams' medium E supplemented with epidermal growth factor to test for chromosomal aberrations and SCEs. For examination of RDS, hepatocytes were incubated in Williams' medium E containing 5-bromo-2'-deoxyuridine. Safrole-DNA adducts were detected by a nuclease P1-enhanced 32P-postlabeling assay. A single dose of safrole induced significant SCEs and RDS, while chromosomal aberrations were induced by 5 repeated doses. Two major and 2 minor DNA adducts were detected by both a single dose and 5 repeated doses. PCP significantly decreased safrole-induced cytogenetic effects and RDS, and caused a decrease in DNA adducts formed by safrole. These results suggest that safrole is capable of inducing SCEs, chromosomal aberrations, and RDS in the rat liver in vivo and that these effects may be induced by the sulfuric acid ester metabolite that can bind DNA.

Analysis of cytogenetic effects and DNA adduct formation induced by safrole in Chinese hamster lung cells

Safrole (1-allyl-3,4-methylenedioxybenzene) was tested for its ability to induce sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) and to form DNA adducts in Chinese hamster lung (CHL) cells, in order to investigate the relationship between cytogenetic effects and DNA adduct formation under the same treatment conditions. The cells were treated with 0.025-0.2 mg/ml safrole in the presence or absence of rat liver postmitochondrial supernatant fraction (S9). Safrole induced significant SCEs and CAs dose-dependently in the presence of S9. SCEs ranged in number from 15.6 to 21.1 SCEs/cell and CAs were observed in 4-37% of cells. Using the 32P-postlabeling assay, two major and two minor safrole-DNA adducts were detected in DNA digests obtained from CHL cells in the presence of S9. The levels of total DNA adducts ranged from 1.3 to 22.8 adducts/10(7) nucleotides. The two major adducts were shown to be guanine derivatives since these adducts comigrated on polyethylenimine plates with the adducts produced by the reaction of safrole with 2'-deoxyguanosine 3'-monophosphate. A correlation was seen between DNA adducts and SCEs or CAs. Neither induction of SCEs and CAs nor formation of DNA adducts was observed in the absence of S9. These findings suggest that SCEs and CAs induced by safrole result from covalent DNA modification metabolically activated by S9 in cultured cells.

Hepatic drug metabolizing enzymes induced by clofibrate in rasH2 mice

Hepatic drug metabolizing enzyme activities were determined, after treatment with clofibrate, in transgenic mice carrying human c-Ha-ras (rasH2 mice). Changes in the drug metabolizing enzyme activities in these mice by gene integration were also evaluated. Male and female rasH2 mice (Tg) and the litter mates not carrying the gene (non-Tg) received orally 500 mg/kg of clofibrate or the vehicle for 12 consecutive days. Liver homogenate and microsomes were prepared and the contents and activities of cytochrome P450 (CYP), cytochrome b5 content and enzyme activities related to peroxisome proliferation were determined. Relative liver weights, CYP4A and activities of catalase and carnitine palmitoyl transferase increased to the same extent in Tg and non-Tg mice treated with clofibrate. In Tg and non-Tg groups that received vehicle, contents and activities of CYP and cytchrome b5 contents were comparable. It was concluded that gene integration did not alter drug metabolizing enzymes and responses to clofibrate.

Parotid gland papillary cystadenocarcinoma in a Fischer 344 rat

A spontaneous parotid gland tumor with histomorphologic features characteristic of cystic and papillary growth was found in a 72-week-old F344 rat. The tumor had a prominent cystic appearance and invasive growth into the dermis beyond the muscular layer of the skin. The cyst walls were lined by a single layer of cuboidal to tall columnar epithelium with prominent papillary projections continuous with the cyst lining. The tumor cells had mucoid, pale cytoplasm and medium to large nuclei. The myoepithelium did not appear to be associated with the tumor cysts and the papillae. Atrophic parotid gland tissues were seen between cysts and in the periphery of the cystic lesions. In light of these findings, the tumor was diagnosed as papillary cystadenocarcinoma of parotid gland; this is the first description of a salivary gland papillary cystadenocarcinoma in a rat.

Comparison of the mutational spectra of the lacZ transgene in four organs of the MutaMouse treated with benzo[a]pyrene: target organ specificity

We recently demonstrated that not all organs with a high rate of induction of mutation in the lacZ transgene develop tumors in the lambdalacZ transgenic mice (MutaMouse) used for a long-term carcinogenicity study with benzo[a]pyrene (BP). To better understand the role of chemical-induced in vivo mutations in carcinogenesis, we compared the mutational spectra of the lacZ transgene in four organs of the MutaMouse obtained 2 weeks after five daily consecutive oral treatments with 125 mg/kg/day BP. lacZ transgenes were analyzed in two target organs (forestomach and spleen) and two non-target organs (colon and glandular stomach) for BP-induced carcinogenesis in MutaMouse, and all of these organs were highly mutated in the lacZ transgene. The sequence data showed similar mutational spectra of the lacZ transgene between the two target organs; the predominant mutations were G:C-->T:A transversions (55% and 50% for forestomach and spleen, respectively), followed by deletions (20% and 21% for forestomach and spleen, respectively) mainly at G:C site. The frequent G:C-->T:A transversions are consistent with reports of the mutational spectra produced in the p53 gene in tumors generated in rats and mice exposed to BP. In contrast, the mutational spectra of the lacZ transgene in the two non-target organs are different from those in the target organs, and are also suggested to differ from one another. These findings suggest an organ/tissue-specific mechanism of mutagenesis.

Auto-induction of E5110 metabolism, a novel non-steroidal anti-inflammatory drug, during toxicokinetic studies in beagle dogs

Following single-dose intravenous and oral studies to determine the absolute bioavailability of E5110 in beagle dogs, repeated dose pharmacokinetic studies were conducted as toxicokinetics in a subacute toxicity test. E5110 was administered orally once a day for 91 days at doses of 0, 1, 10, 50 and 250 mg/kg/day to dogs. On the first day during repeated administration, the Cmax and AUC values of E5110 in females were lower than those for males, and it seems that this may be due to a sex-related difference in the activity of cytochrome P450 (CYP) 3A. During repeated administration of E5110, the plasma levels of E5110 on day 15 and day 91 were markedly lower than those on the first day. On day 91, the AUCs for E5110 were 55.9%, 38.8%, 10.9% and 7.8% in males, and 76.2%, 80.3%, 10.5% and 11.9% in females on the first day, for doses of 1, 10, 50 and 250 mg/kg/day, respectively. Liver microsomes prepared after the last dose of E5110 showed increased activities of benzphetamine N-demethylase, p-nitroanisole O-demethylase, and aminopyrine N-demethylase, at doses of 1 mg/kg/day or more. A dose-dependent increase in P450 content was also observed. Furthermore, the capacity for 5-hydroxylate E5110 was increased, and Western blot analysis indicated an induction of CYP2B and 3A; therefore CYP3A may contribute to a main metabolic pathway of E5110. These results suggested that the decrease in plasma concentrations of E5110 that were observed during repeated administration represents a typical case of auto-induction of the phenobarbital type.

[General toxicity study of gadobenate dimeglumine formulation (E7155) (3)--4-week repeated dose intravenous toxicity study followed by 4-week recovery period in rats]

A 4-week repeated dose toxicity study of gadobenate dimeglumine formulation (E7155) was conducted in Sprague-Dawley rats to assess its non-clinical safety. E7155 was administered intravenously at doses of 0.3, 1.0 and 3.0 mmol/kg/day to male and female rats once a day during 4 weeks. The reversibility of toxicity was evaluated during a 4-week recovery period at 3.0 mmol/kg/day. At 0.3 mmol/kg/day and higher, vacuolation of the cortical epithelium was seen in the kidneys and an increase in the incidence of local damage at the injection sites. In the 1.0 and 3.0 mmol/kg/day male and female groups, scabbing/ulceration of the tail at the injection sites, macroscopic pale/thickened fundic mucosa in the stomachs, vacuolation of the urinary bladder, and mucosal mineralization with epithelial hyperplasia of the glandular stomach were found. In the 1.0 and 3.0 mmol/kg/day male group and 3.0 mmol/kg/day female group, increases of water consumption and urinary potassium excretion, increased kidney weight and enlargement of the kidneys were observed. In the 3.0 mmol/kg/day male and female group, hepatocyte necrosis with inflammatory cells in the liver and epithelial degranulation in the interlobular ducts of the salivary glands were found. In addition, in the 3.0 mmol/kg/day male group, increases in plasma sodium and decreases of urinary sodium and chloride excretion, and degenerative changes in the testes and epididymides were observed. After the 4-week recovery period, except for an increase in urinary potassium excretion, increased kidney weights and changes in the testes and epididymides, all of the above findings had complete or partial recovery. Vacuolation of renal tubular cells was common, expected, and known as an adaptive change of treatment with hypertonic solutions, and an increase in the incidence of local damage at the injection sites was due to irritation by repeated intravenous dosing with hypertonic solutions. Therefore, these changes were not toxic changes. In conclusion, the dose level of 0.3 mmol/kg/day should be regarded as the No Observed Adverse Effect Level (NOAEL) after repeated administration of E7155 in rats.

[General toxicity study of gadobenate dimeglumine formulation (E7155) (1)--single dose intravenous and intracisternal toxicity study in rats]

Gadobenate dimeglumine formulation (E7155) was evaluated for its general toxicity potential following a single intravenous and intracisternal administration to rats. Dosage levels tested were 3.3, 4.5, 6.0 and 8.0 mmol/kg at the injection rate of 6 ml/min and 7.50, 8.89, 10.54 and 12.50 mmol/kg at 1 ml/min for the intravenous administration route, and 0.15, 0.21, 0.29 and 0.40 mmol/kg for the intracisternal administration route. Parameters measured during the 14-day observation period were mortality, clinical signs and macroscopic examination. After intravenous administration at the injection rate of 6 ml/min, twitches, respiratory blocking and prostration were observed at 6.0 mmol/kg, and dyspnoea and sedation at 3.3 and 4.5 mmol/kg. Deaths occurred within 1 min after administration at 6.0 mmol/kg and above. LD50 values were 7.97 mmol/kg in males and 6.22 mmol/kg in females. After intravenous administration at the injection rate of 1 ml/min, shallow breathing, twitches and sedation were observed at 7.50 mmol/kg and above and respiratory arrest at 8.89 mmol/kg. Deaths occurred within 1 min after administration at 8.89 mmol/kg and above. LD50 values were 9.0 mmol/kg in males and 9.7 mmol/kg in females. After intracisternal administration, symptoms consisted of sedation, staggering gait, dyspnoea, twitches and ataxia at 0.15 mmol/kg and above, prostration, paralysis of forelimbs, and/or hind limbs and chromodacryorrhea at 0.21 mmol/kg, and convulsions at 0.29 mmol/kg and above. Deaths occurred within 7 days after administration at 0.21 mmol/kg and within 5 min at 0.29 mmol/kg and above. LD50 values were 0.42 mmol/kg in males and 0.25 mmol/kg in females.

[Mutagenicity study of gadobenate dimeglumine formulation (E7155) (2)--Chromosome aberration test with human lymphocytes in culture]

The mutagenic potential of gadobenate dimeglumine formulation (E7155) was studied by the chromosome aberration test in cultured human lymphocytes. Human lymphocytes were exposed to E7155 at 0.078-10 mM both in the presence and absence of S9 mix derived from rat livers. Three dose levels (2.5-10 mM) were selected for the metaphase analysis. E7155 induced no increase in the incidence of aberrant cells or polyploid cells in any treatments both in the presence and absence of metabolic activation. Thus, it is concluded that E7155 has shown no evidence of clastogenic or polyploidy-inducing activity under these experimental conditions.

[General toxicity study of gadobenate dimeglumine formulation (E7155) (4)--4-week repeated dose intravenous toxicity study followed by 4-week recovery period in dogs]

Gadobenate dimeglumine formulation (E7155), at doses of 0 (physiological saline), 0.25, 0.5, 1 and 2 mmol/kg/day of body weight, was administered intravenously to male and female beagle dogs once daily for 4 consecutive weeks in order to evaluate the subacute toxicity of the test article. Reversibility of toxicity was evaluated during a 4-week recovery period at 1 and 2 mmol/kg/day. No toxicologically significant changes were observed at 0.25 and 0.5 mmol/kg/day. In animals receiving 1 or 2 mmol/kg/day, transient swelling and redness of the facial and eye areas, lethargy, decreased activity, emesis, retching, watery or unformed stool, decreased body weight or body weight gain, decreased food consumption, decreased hematocrit and hemoglobin concentration, increased APTT, increases in plasma ALP, GPT or gamma-GT, decreased plasma inorganic phosphorus, total protein or albumin, increased liver or kidney weight, subacute inflammatory infiltrates, loss of centrilobular hepatocytes or hepatocellular cytoplamic vacuolation in the liver, vacuoles in the epithelial cells of the renal tubles and/or hypocellularity in the bone marrow were seen. The results of toxicokinetic analysis showed that systemic exposure was similar in males and females, and there was no accumulation of the test material over the treatment period, although AUC tended to be enhanced by slightly more than the proportionate dose increase. These effects were recovered or tended to be reversed after a post-dosing period for 4 weeks. In conclusion, the No Observed Adverse Effect Level (NOAEL) was 0.5 mmol/kg/day.

[Reproductive and developmental toxicity study of gadobenate dimeglumine formulation (E7155) (2)--Combined study of effects on fertility and embryo-fetal toxicity in female rats by intravenous administration]

The influence of gadobenate dimeglumine formulation (E7155) on fertility and general reproductive performance and embryo-fetal development was assessed in female Sprague-Dawley rats. E7155 was administered by intravenous injection at a dose of 0.3, 1.0 or 2.0 mmol/kg/day to groups of 22 female rats for 15 days before pairing. Treatment was continued throughout mating and up to Day 17 of gestation. Control animals received 0.9% sterile physiological saline throughout the same period. All females were killed on Day 20 of gestation for examination of their uterine contents. There were no toxic clinical signs of treatment. The body weight and food consumption of females before pairing and during gestation were not affected by treatment. Estrous cycles, mating performance, litter size and fetal weight, survival and development were also not affected by treatment. Based on the above results, the No Observed Adverse Effect Level (NOAEL) of E7155 was 2.0 mmol/kg/day for general toxicologic effects and reproduction of female rats and the development of their fetuses.

[Muscular irritation study of gadobenate dimeglumine formulation (E7155) in rabbits]

To examine the local muscular irritation potency of gadobenate dimeglumine formulation (E7155), E7155 was injected into the right vastus lateralis muscle of male Kbl:JW rabbits, and saline as the negative control was injected into the left muscle. Half of the animals were subjected to necropsy at 2 or 14 days after administration. The muscles were examined macroscopically and histopathologically. Also, 0.425 w/v% and 1.7 w/v% acetic acid solutions were used as a positive control. In macroscopic observation, hemorrhage with white or brown coloration was seen in the muscles treated with E7155 at 2 days after administration, and white coloration was seen in one case at 14 days after administration. In histopathological examination, slight or moderate hemorrhage, edema, cellular infiltration, degeneration of muscle fibers and necrosis of muscle fibers were seen in the muscles treated with E7155 at 2 days after administration, and very slight to slight cellular infiltration, degeneration of muscle fibers, fibrosis, calcification of muscle fibers and foreign body giant cells were seen in the muscles treated with E7155 at 14 days after administration. The changes in the muscle caused by E7155 were definitely less than those caused by the 1.7 w/v% acetic acid solution at both 2 and 14 days, and slightly less and definitely less than those caused by the 0.425 w/v% acetic acid solution at 2 days and 14 days after administration, respectively. The changes caused by E7155 were more severe than those caused by saline. It was concluded that the local muscular irritation potency of E7155 could be classified at Grade 2.

[Reproductive and developmental toxicity study of gadobenate dimeglumine formulation (E7155) (1)--Fertility study in male rats by intravenous administration]

The influence of gadobenate dimeglumine formulation (E7155) on general reproductive performance and fertility in male rats of the Sprague-Dawley strain was assessed in this study. E7155 was administered by intravenous injection at a dosage of 0.3, 1.0, or 2.0 mmol/kg/day to groups of 22 male rats for 13 weeks. Control animals received 0.9% sterile physiological saline throughout the same period. After four weeks of treatment, each male was paired with an untreated female of the same strain. Each male was paired again after 10 weeks of treatment with another untreated female of the same strain. All females were killed on Day 14 of gestation for examination of pregnancy status. No significant toxicological signs associated with systemic exposure to E7155 were observed. There were no effects of treatment with E7155 on body weight gain, food consumption, macroscopic findings, reproductive organ weights and sperm count or sperm motility in male rats. Mating performance after pairing at Weeks 4 and 10 of treatment as well as litter size and number of survival embryos on Day 14 of gestation were not affected by paternal treatment with E7155. From these results, the No Observed Adverse Effect Level (NOAEL) of E7155 was 2.0 mmol/kg/day for general and reproductive toxicity parameters in male rats treated with E7155 and for development in their embryos.

[Reproductive and developmental toxicity study of gadobenate dimeglumine formulation (E7155) (3)--Study of embryo-fetal toxicity in rabbits by intravenous administration]

Gadobenate dimeglumine formulation (E7155) was daily administered by intravenous injection at 0.3, 0.9 or 2.0 mmol/kg/day to mated NZW female rabbits (20/group) to assess the effect on embryo-fetal development. Treatment with 2.0 mmol/kg/day caused initial, notable loss of body weight and reduction in food consumption. Slightly reduced body weight gain and food intake were recorded at 0.9 mmol/kg/day. There were no obvious adverse effects in dams given E7155 at 0.3 mmol/kg/day. There was a slightly higher incidence of early intrauterine deaths at 0.9 and 2.0 mmol/kg/day. Morphological examination of fetuses at 2.0 mmol/kg/day revealed small eye/microphthalmia and/or retinal irregularities in three fetuses from three separate litters. There was also an increase in the incidence of additional and/or fused sternebral centres and 20-thoracolumbar vertebrae at this dosage. From these results, the No Observed Adverse Effect Level (NOAEL) for general toxicity of dams and embryo-fetal development was 0.3 mmol/kg/day.

[Mutagenicity study of gadobenate dimeglumine formulation (E7155) (3)--Micronucleus test in rat bone marrow cells]

The mutagenic potential of gadobenate dimeglumine formulation (E7155) was studied by the micronucleus test in rats. Single intraperitoneal injection of E7155 to Sprague Dawley rats at the dose of 5295.2 mg/kg (5 mmol/kg) did not induce any statistically significant increase in the frequency of micronucleate cells in the bone marrow sampled after 18, 42 and 66 hr from time of administration.

[General toxicity study of gadobenate dimeglumine formulation (E7155) (2)--Single dose intravenous toxicity study in dogs]

Gadobenate dimeglumine formulation (E7155) was given by single intravenous injection to 4-5 month-old beagle dogs at doses of 2 or 6 mmol/kg. Treatment was followed by a 14-day observation period in order to evaluate the test article's toxicity. The male and female dogs at 6 mmol/kg vomited and showed reddened gums and ears as clinical signs. One male dog at 6 mmol/kg was euthanized approximately 23 hr after administration due to its very poor clinical condition, which included an unwillingness to move, pale gums and weak pulse. Body weight was decreased at 6 mmol/kg, and also slightly at 2 mmol/kg. Decreased food consumption was noted both at 2 and 6 mmol/kg. Hematology for the euthanized male at 6 mmol/kg showed increases in the total white blood cell count, packed cell volume, hemoglobin and red cell count and a decrease in the platelet count. Biochemistry showed a dose-related increase in alkaline phosphatase, GPT and GOT at 2 and 6 mmol/kg. Males and females at 6 mmol/kg showed increases in bilirubin, calcium and urea, and a reduction in glucose. Females at 6 mmol/kg also showed a reduction in total protein. Urinalysis showed an increase in pH at 2 mmol/kg and above. For females at 6 mmol/kg, an increase in urine volume and a decrease in specific gravity and osmolality were noted. An increase in relative liver and kidney weights was recorded for males and females dosed at 6 mmol/kg. For the euthanized male at 6 mmol/kg, postmortem examination revealed a pale liver with rounded edges and an accentuated lobular pattern, and dark material on the gastro-intestinal mucosal surface. In macroscopic pathology, the male at 6 mmol/kg revealed single liver cell necrosis, minimal early hyperplasia in small biliary ductules, inflammatory cells in the sinusoidal and portal tracts, centrilobular inflammatory cells, diffuse vacuolation of the hepatocytes and sinusoidal dilatation in the liver, and cortical tubular vacuolation in the kidneys. In the female dog treated at 6 mmol/kg, hyperplasia in the small biliary ductules, inflammatory cells in the portal tracts, diffuse vacuolation of hepatocytes and sinusoidal dilatation were seen in the liver, and increases in the severity of cortical tubular basophilia, cortical tubular dilatation and cortical tubular casts were detected in the kidney. Based on these results, the lethal dose of E7155 was set at 6 mmol/kg. It is also concluded that a dose of 2 mmol/kg was tolerated in the beagle dog after a single injection followed by a 14-day observation period.

[Mutagenicity study of gadobenate dimeglumine formulation (E7155) (1)--Reverse mutation assays in S. typhimurium and E. coli tester strains]

The ability of gadobenate dimeglumine formulation (E7155) to cause gene mutations was assessed in five strains of Salmonella typhimurium (TA100, TA1535, TA98, TA1538, and TA1537) and a strain of Escherichia coli (CM891; WP2, uvrA-, pKM101) using the Ames test (agar plate assay). The results suggest that E7155 is non-mutagenic towards these bacterial tester strains.

Toxicological response of rats to a novel monoamine oxidase type-A inhibitor, (5R)-3-[2-((1S)-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5- methoxymethyl-2-oxazolidinone (E2011), orally administered for 13 weeks

(5R)-3-[2-((1S)-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5- methoxymethyl-2-oxazolidinone (E2011) is a novel monoamine oxidase type-A (MAO-A) inhibitor. In order to assess toxicological profiles of E2011, doses of 0 (as controls), 30, 100 mg/kg of E2011 were administered to male and female Sprague-Dawley rats once a day for 13 weeks orally by gavage. No mortality or any toxic signs except salivation occurred due to E2011 treatment. Decreased body weight gain and food consumption, increases of alkaline phosphatase and increases of liver weight were the major treatment-related findings observed predominantly in the 100 mg/kg group. Histological examination revealed nuclear enlargement of hepatocytes with appearance of altered cell foci in some cases, and acinar atrophy in Harderian glands in the 100 mg/kg group. Since the histopathological findings in the liver were indicative of an ongoing carcinogenic process, glutathione S-transferase placental form (GST-P) positive hepatic foci were identified immunohistochemically and examined morphometrically. Although GST-P positive hepatic foci were detected in all groups including controls, the number and area of GST-P positive hepatic foci were significantly higher in female rats treated with 100 mg/kg than those in controls. In this paper, possible mechanisms of specific lesions in the liver and Harderian glands will be discussed.

Multiple organ mutation in the lacZ transgenic mouse (Muta mouse) 6 months after oral treatment (5 days) with benzo[a]pyrene

We have recently demonstrated that not all organs with high rates of mutation in the lacZ transgene develop tumors using the Muta Mouse. To better understand the role of in vivo mutation in carcinogenesis, we examined the mutant frequencies (MF) of the lacZ transgene in tumor-bearing and non tumor-bearing organs. MF, recovered after 2 weeks (the data taken from our previous study) and after 26 weeks following oral doses of 125 mg kg-1 day-1 benzo[a]pyrene (BP) for five days were compared. The organs examined included the target organs (forestomach, spleen, and lung) and non-target organs (colon, glandular stomach, and liver) for BP carcinogenesis. The data indicated that lacZ MF were markedly increased over spontaneous frequencies in the organs examined and that the organ which showed the highest MF was the colon, followed by the forestomach>spleen>glandular stomach, liver, and lung in that order. These findings indicate that the MF of the lacZ transgene in each organ, even 26 weeks after the start of the treatment does not fully correlate with the known target organs of BP. Furthermore, the lacZ MF in a non-papilloma region of a forestomach with a papilloma was equivalent to the two highest MF observed in the healthy colon (non-target organ) of mice at 26 weeks. These observations also indicate that the generation of tumors requires the induction of mutations as well as other factor(s) specific to the target organs. These results clearly suggest that highly mutated organs do not always progress to tumors in the transgenic mouse.

Giant cell tumor of bone in an aged Fischer 344 rat

A giant cell tumor (GCT) was detected on the distal end of the femur in a 98-wk-old male Fischer 344 rat. The yellowish white mass had expanded, compressing adjacent muscle tissues. The tumor had an osteolytic and relatively homogeneous appearance and was composed of multinuclear giant cells scattered in a mass of mononuclear stromal cells. No osteoid tissue formation was observed. The tumor cells were strongly immunoreactive for ED-1 and some were also positive for alpha-smooth muscle actin, suggesting that the tumor originated from the monocyte/macrophage lineage showing myofibroblastic differentiation. This is the first report concerning spontaneous GCT of bone in a rat.

A short-term assessment of tumor-promotion activity in the livers of rats treated with two genotoxic methylating agents: dimethylnitrosamine and methylnitrosourea

Induction of replicative DNA synthesis (RDS) and mitoinhibitory effects were studied in the hepatocytes of F344 rats exposed in vivo to the methylating agents dimethylnitrosamine (DMN, hepatocarcinogen) and methylnitrosourea (MNU, non-hepatocarcinogen). Cytotoxicity and chromosome aberrations (CA) in rat liver were also investigated to clarify the cause of changes in RDS and mitoinhibitory effects, respectively. The animals were killed at different intervals (up to 14 days) after a single oral dose, or 1 day after 7 or 14 days of repeated oral doses. The hepatocytes were isolated and cultured with Williams' medium E to assess their RDS, mitoinhibitory effects and CA. Mitoinhibitory effects were investigated by monitoring their effect on epidermal growth factor-induced replicative DNA synthesis (EGF-induced RDS) in rat hepatocytes. Hepatotoxic effects were assessed by measuring aspartate transaminase and alanine transaminase in the plasma and by histopathological examination. In the single-dose study, DMN (20 mg/kg body weight (bw)) induced both RDS and hepatotoxicity. MNU (50 mg/kg bw) induced RDS without causing hepatotoxicity, and thus was classified as a mitogen. In the repeated-dose study, DMN (4 mg/kg bw) induced both RDS and hepatotoxicity, but MNU (10 mg/kg bw) induced neither. Both inhibition of EGF-induced RDS and induction of CA were observed in the hepatocytes of rats treated with DMN, but were not observed with MNU in both single and repeated dose studies. The mitoinhibitory effect of DMN persisted for 14 days after the single dose and time dependently increased for 14 days after repeated administration. This mitoinhibitory effect correlated positively with CA. The mitoinhibitory effect was thought to be attributable to the DNA-damaging effect that induces CA. We concluded that the differences which we found in this study between DMN and MNU contribute to the differences in their hepatocarcinogenicity. Our findings suggested that both cell proliferative and mitoinhibitory properties play an important role in tumor promotion, and measuring them may provide an ancillary index that is useful in predicting hepatocarcinogenicity.

In vivo genotoxicity and DNA adduct levels in the liver of rats treated with safrole

The induction of chromosome aberrations, sister chromatid exchanges (SCEs), and the formation of DNA adducts was studied in hepatocytes of F344 rats exposed in vivo to safrole. Hepatocytes were isolated 24 h after a single dose of safrole or five repeated doses (once a day) by gastric intubation and allowed to proliferate in Williams' medium E supplemented with epidermal growth factor. Cells were fixed after 48 h in culture. Safrole-DNA adducts were detected by a nuclease P1-enhanced 32P-post-labeling assay in isolated hepatocytes from the rats. While a single dose was not sufficient to induce detectable levels of chromosome aberrations at the time of assay, five repeated doses induced these changes with a maximum frequency of 13.4%, compared with the control value of 1.8%. Both a single dose and five repeated doses induced significant SCEs, to a maximum frequency of 0.81 SCEs per chromosome, while the control value was 0.59 SCEs per chromosome. Two major and two minor DNA adducts were detected after treatment with either a single dose or five repeated doses. The maximum amount of total DNA adducts was 89.8 DNA adducts/10(7) nucleotides. These results show that safrole is a genotoxic carcinogen in the rat liver in vivo and suggest that the cytogenetic effects of this compound may result from covalent DNA modification in the rat liver. This in vivo cytogenetic assay should provide a useful means of evaluation of the genotoxicity of hepatocarcinogens.

Quinoline-induced chromosome aberrations and sister chromatid exchanges in rat liver

Induction of chromosome aberrations and sister chromatid exchanges (SCEs) was studied in hepatocytes of F344 rats exposed in vivo to the hepatocarcinogen quinoline (Q). Hepatocytes were isolated 4-48 hr after a single dose of 200 mg/kg body weight or 24 hr after 28 repeated doses (once a day) of 25-200 mg/kg body weight/day by gastric intubation, and allowed to proliferate in Williams' medium E supplemented with epidermal growth factor. Cells were fixed after a culture period of 48 hr. A single dose of Q induced chromosome aberrations in up to 22% of metaphase cells, and SCEs with a frequency of up to 1.27 per chromosome 12 hr after the dose, while the control values were 1% and 0.63 per chromosome, respectively. Treatment with 28 repeated doses of Q induced significant chromosome aberrations and SCEs dose-dependently. Cytogenetic damage induced induced in the liver by repeated doses of Q was greater than induced by a single dose. Furthermore, Q induced replicative DNA synthesis in the liver, but failed to induce micronucleus formation in the bone marrow. The noncarcinogen 8-hydroxyquinoline was also examined and found to be essentially non-genotoxic to rat liver. These results show that Q is a genotoxic carcinogen to rat liver and the present method of in vivo cytogenetic assay should be useful for evaluating the genotoxicity of hepatocarcinogens.

Mutagenicity of dihydroxybenzenes and dihydroxynaphthalenes for Ames Salmonella tester strains

The mutagenicity of 3 dihydroxybenzene (DHB) and 9 dihydroxynaphthalene (DHN) isomers was examined by using 5 different Ames Salmonella mutagenicity tester strains in the presence and absence of phenobarbital and 5,6-benzoflavone-treated rat liver S9-mix. Of the 3 DHB isomers, 1,4-DHB (hydroquinone) was mutagenic, and of the 9 DHN isomers, 1,3-DHN (naphthoresorcinol), 1,4-DHN (hydronaphthoquinone), 1,6-DHN and 1,7-DHN were mutagenic. Mutagenicity of all the compounds tested was observed in the absence of S9-mix, while 1,4-DHN and 1,6-DHN were also mutagenic in the presence of S9-mix. The mutagenicity of 1,4-DHB and 1,4-DHN for TA104, which is a strain sensitive to oxidative mutagens, was almost completely or partially inhibited by superoxide dismutase (SOD) and/or catalase, indicating the involvement of activated oxygen species in mutagenesis. Furthermore, from the finding that the 4 DHNs were mutagenic for TA2637, the strain sensitive to frameshift mutagens, it is possible that the mutagenicity of DHNs for S. typhimurium was also attributable to DNA adducts that form with quinones and/or semiquinones through oxidation of DHNs. The mutagenicity of 1,3-DHN, which showed the largest number of revertants in strains TA100, TA98, TA2637 and TA104, was greatly decreased, when their pKM101 plasmid-deficient strains, TA1535, TA1538, TA1537 and TA2659 were used. This observation suggests that an SOS repair system was involved in the mutagenesis of 1,3-DHN for S. typhimurium.

Effect of E5510 on anastomotic intimal hyperplasia and platelet aggregation in dogs

We examined the effect of an antiplatelet agent, E5510, which inhibits both platelet aggregation and release of platelet-derived growth factor (PDGF), on anastomotic intimal hyperplasia and platelet aggregation. Twenty Beagle dogs underwent infrarenal aortic reconstruction with an expanded polytetrafluoroethylene (ePTFE) graft 5 mm in diameter and 3 cm long. The dogs were divided into three groups: placebo (control group, 7 dogs), E5510 1 mg/day (1-mg group, 6 dogs), and E5510 4 mg/day (4-mg group, 7 dogs). E5510 was administered orally 2 h before operation and once daily for 3 months after operation. Grafts were harvested 3 months after operation. All 13 grafts in the treated groups remained patent without evidence of intimal hyperplasia, whereas only 4 of 7 grafts (57%) remained patent in the control group, including 1 graft with > 50% stenosis. Three occluded grafts showed severe intimal hyperplasia at the anastomoses. The platelet aggregation ratio (PAR) with collagen (100 micrograms/ml) before drug administration at 3 months in the 4-mg group was significantly lower than that in the control and 1-mg groups. PAR after drug administration at 3 months in the 1- and 4-mg groups was significantly lower than that in the control group. Intimal thickness at the distal anastomosis was 817 +/- 190 microns in the control group, 240 +/- 80 microns in the 1-mg group, and 197 +/- 28 microns in the 4-mg group. Intimal thickness in the control group was significantly greater than that in the 1- and 4-mg groups. Smooth muscle cell (SMC) values in the intima at the distal anastomosis were 65.6 +/- 4.4% extinction (%E) in the control group, 47.6 +/- 3.4%E in the 1-mg group, and 51.3 +/- 3.5%E in the 4-mg group. SMC value in the control group was significantly greater than that in the 1- and 4-mg groups. E5510 inhibited PAR and reduced the degree of anastomotic intimal hyperplasia.

Developmental aspects of a unique glutathione S-transferase subunit Yx in the liver cytosol from rats with hereditary hyperbilirubinuria. Comparison with rat fetal liver transferase subunit Yfetus

The unique glutathione S-transferase (GST) subunit Yx, which is undetectable in normal adult rat liver cytosol, was shown to occur in the liver cytosol of rats with hereditary hyperbilirubinuria (EHB). The Yx subunit is a member of the Alpha-class GST subunits, and is immunologically closely related to the Yc subunit. The Yx subunit has an apparent M(r) of 26,400, different from those of Ya (M(r) 25,800), Yb1 and Yb2 (both M(r) 27,200) and Yc (M(r) 28,400). During postnatal development in livers of EHB rats, the Yx subunit concentration in either sex was highest during the first week post partum and declined rapidly with age. Although the concentration of subunit Yx at 8 weeks of age accounted for about 60% in females and 40% in males of that observed in 1-week-old 'neonatal' male EHB rats, concentrations in females thereafter increased gradually to almost the neonatal level and remained at this high level at least up to 37 weeks of age, whereas the concentration in males did not increase again. Thus the post-pubertal Yx subunit concentration was 2-fold higher in females than in males. In contrast, in normal Sprague-Dawley rat liver, the Yfetus subunit, with the same M(r) as the Yx subunit, had the highest concentration in 10-day-old animals, declined rapidly thereafter, and was not detectable in the post-pubertal period. The Yfetus subunit was also immunoreactive with an antibody against GST YcYc. The analysis of GST subunits by reverse-phase h.p.l.c. revealed that the Yx subunit was eluted at a retention time different from other known subunits, but coincided with that of Yfetus. The N-terminal amino acid sequence of the Yx subunit displayed a high degree of sequence similarity to that of the Yfetus subunit. These data suggest that the Yx subunit in EHB rats may be very similar to, if not identical with, the Yfetus subunit.

The unique feature of dog liver cytosolic glutathione S-transferases. An isozyme not retained on the affinity column has the highest activity toward 1,2-dichloro-4-nitrobenzene

In the adult dog liver cytosol we identified four glutathione S-transferase (GST) subunits, Yd1 (Mr 26,000), Yd2 (Mr 27,000), Yd3 (Mr 28,000), and Ydf (Mr 27,400), and purified GST forms comprising Yd1, Yd2, and Yd3, to apparent homogeneity. Unlike rat transferases the enzyme activity toward 1,2-dichloro-4-nitrobenzene (DCNB) was not retained on the affinity column. Thus the DCNB-active enzyme, GST YdfYdf, from the flow-through fraction of the affinity column was also purified to homogeneity by gel filtration, DE52 chromatography, chromatofocusing, and hydroxylapatite column chromatography. Immunoblot analysis of dog GSTs revealed that the subunits Yd1, Yd2, and Yd3 belong to the pi, alpha, and mu class, respectively. On the contrary, Ydf had no reactivity with antibodies raised against any of the three classes of GST. Each subunit, Yd1, Yd2, Yd3, and Ydf, was distinguishable by its own retention time on reverse-phase high performance liquid chromatography. N-terminal amino acid sequences of the dog GSTS Yd1Yd1 and Yd3Yd3 revealed a high degree of homology to the pi and mu class transferases from rat, human, and mouse, respectively, while the N terminus of Yd2Yd2 is blocked. N-terminal amino acid sequences of GST YdfYdf showed no homology to any of the three classes of GST. The most significant property noted of GST YdfYdf is the high specific activity toward DCNB, exceeding by 1 order of magnitude the corresponding values for the known mu class GSTs. The present results strongly suggest that dog GST YdfYdf is a unique enzyme distinct from the hitherto characterized GST isozymes.

Decrease in the specific forms of cytochrome P-450 in liver microsomes of a mutant strain of rat with hyperbilirubinuria

Eisai-hyperbilirubinuria rats (EHBR) is a mutant originated from Sprague Dawley rats. The activities of UDP-glucuronyltransferase and drug metabolizing enzymes in EHBR were compared with those in Sprague Dawley rats as the control. The activity of aniline hydroxylase was significantly increased in liver microsomes of EHBR whereas the activity of ethylmorphine N-demethylase was found to be significantly decreased in EHBR as compared to control rats. In addition, the activity of testosterone 7 alpha-hydroxylase was increased in EHBR whereas the activity of testosterone 6 beta-hydroxylase was significantly decreased in EHBR as compared to control rats. Western blot analysis of liver microsomes of EHBR with antibodies to P-450IA2, P-450IIB1, P-450IIC11 and P-450IIIA2 showed that the amounts of P-450IIB1 and P-450IIIA2 in liver microsomes were significantly lower in EHBR than in control rats. These results indicated the form-specific alteration in the amounts of cytochrome P-450 in liver microsomes of EHBR.

Induction and immunohistochemical localization of cytochrome P-450 PCN by non-steroidal compound, in rat liver microsomes

Induction of cytochrome P-450 PCN (P-450 PCN) by non-steroidal compound, M79193 (cyclohexane spiro-2,6-chloro-1'-(3-dimethyl-aminopropyl) spiro(chroman-4,4'-imidazolidine)-2',5'-dione], was investigated in both sexes of rats. The immunohistochemical localization of P-450 PCN was also studied in liver lobules of untreated and M79193-treated male rats. Immunoblot analysis of rat liver microsomes with anti-P-450 PCN indicated that the amount of P-450 PCN increased 5- to 7-fold by the treatment with M79193, but no increase was observed in P-450 PB-1 (P450IIB1) or P-450 MC-1 (P-450IA1). P-450 PCN was uniformly distributed in liver lobule of untreated rats, and was significantly increased by the treatment with M79193 in both the periportal and pericentral regions of the lobules.

Strain differences of rat liver carboxylesterase activities related to the phenotype difference of esterase-3 (egasyn)

It was demonstrated that the inbred strain EHBR had the C phenotype of esterase-3 judging from the absence of liver microsomal beta-glucuronidase and the pattern of esterase activities of liver homogenates after analytical isoelectric focusing. In addition, in the strain EHBR, liver microsomal hydrolase activities of acetanilide and isocarboxazid which are hydrolyzed well by esterase-3 were lower than in outbred Sprague-Dawley rat and inbred LEW rat having the D phenotype of esterase-3. These results suggest that the phenotype difference of esterase-3 is possible to cause the strain differences of liver microsomal carboxylesterase activities.

Effect of aztreonam on immunohistochemical localizations of cytochrome P-450 (M-1) in male rats

The localization of sex-specific cytochrome P-450, P-450 (M-1), was investigated immunohistochemically in the liver of untreated- and Aztreonam-treated male rats. P-450 (M-1) was uniformly distributed in the liver lobule of untreated rats. By treatment with Aztreonam, P-450 (M-1) was decreased more in the periportal region rather than the pericentral region of the lobule. In addition, oxidation of testosterone and 1 alpha-hydroxycholecalciferol catalyzed by P-450 (M-1) was also decreased by Aztreonam administration.

Induction of cytochrome P-450 isozymes by chromanamine derivatives in rat liver

1. Pretreatment of rats with 6-(3-picolyl)amino-2,2,5,8-tetramethylchromane (PATC) for 7 days resulted in a significant increase in the activities of benzphetamine N-demethylase, p-nitroanisole O-demethylase and aniline hydroxylase in liver microsomes prepared 24 h after the last treatment. 2. Analysis by Western blot showed that PATC induces cytochrome P-450 b, P-450 c and P-450 d, which are the major forms of cytochrome P-450 in liver microsomes of rats when pretreated with phenobarbital and 3-methylcholanthrene. 3. Exposure of liver sections to the antibodies to cytochrome P-450 b and P-450 c resulted in intense immunostaining within the centrilobular regions, but produced staining of considerably weaker intensity in the perilobular region. Semiquantitative immunochemical analysis, by image analyser, of cytochrome P-450 b and P-450 c showed that centrilobular hepatocytes were stained more intensively than perilobular hepatocytes. 4. These results indicate that PATC induces cytochromes P-450 b and P-450 c, in the centrilobular hepatocytes to a greater degree than those in the perilobular hepatocytes. 5. Co-administration of PATC with pentobarbital caused a significant increase in pentobarbital sleeping time. Furthermore, PATC was found to cause a decrease in the activity of benzphetamine N-demethylase in liver microsomes prepared 30 min after treatment with the drug.

Dog liver glutathione S-transferase and its strong immunoreactivity with rat transferase-P(7-7)

Dog liver cytosolic glutathione S-transferases (GSTs) were investigated to characterize their properties in comparison with rat liver transferases. Dog liver GSTs after the glutathione affinity column chromatography showed three subunit bands on SDS-polyacrylamide gel electrophoresis. These three subunits, designated as Yd1 (mol.wt 26,000), Yd2 (mol.wt 27,000) and Yd3 (mol.wt 28,000), were distinctly different from rat liver GST subunits, i.e. Ya(1) (mol.wt 26,500), Yb1(3)/Yb2(4) (mol.wt 27,500) and Yc(2) (mol.wt 28,500). Western blot analysis revealed that Yd1, Yd2 and Yd3 were immunoreacted with anti-rat GST 7-7, 1-1 and 3-3 antibodies, respectively. Four transferase activity fractions, I (pH greater than 7.63), II (pH 6.92), III (pH 5.80) and IV (pH 5.65), were obtained from affinity purified GSTs by chromatofocusing. Each fraction exhibited a characteristic substrate specificity. GST-II, III and IV were all strongly immunoreacted with anti-rat GST 7-7 antibody by immunoblotting, thus suggesting the occurrence of the heterogeneity of transferases immunologically related to rat GST subunit 7 in dog liver. Immunohistochemical examination showed that transferases immunoreacted with anti-GST 7-7 antibody have diffusely distributed throughout the lobule, while enzymes related to subunit 3 have been localized in a narrow range of cells around the central vein. These data suggest that GSTs immunologically associated with rat transferase subunit 7 may be major forms in dog liver.

Gangliosides in the blood plasma: levels of ganglio-series gangliosides in the plasma after administration of brain gangliosides

The temporal change in the levels of the gangliotetraose-series gangliosides, i.e., GMla, GDla, GD1b, GT1b, in the blood plasma after intramuscular administration of bovine brain gangliosides (5 mg/kg) to beagle dogs (11.3-12.2 kg) was determined with high sensitivity by a recently developed thin-layer chromatography/enzyme-immunostaining method (Hirabayashi, Y., Koketsu, K., Higashi, H., Suzuki, Y., Matsumoto, M., Sugimoto, M. and Ogawa, T. (1986) Biochim. Biophys. Acta 876, 178-182). The amounts of GMla, GDla, GD1b, GT1b and their combined total in the plasma of beagle dogs before administration of gangliosides were 21 +/- 1, 36 +/- 7, 15 +/- 2, 16 +/- 2 and 88 +/- 6 pmol/ml of blood plasma, respectively. Trapezoidal calculation showed that the times of the maximum levels of GMla, GDla, GDlb, GTlb and the total of the their levels in the plasma were 8.0 +/- 1.2, 8.7 +/- 0.7, 6.3 +/- 2.0, 17.0 +/- 7.0 and 8.7 +/- 0.7 h after the administration of gangliosides, and their maximum concentrations were 517 +/- 37, 654 +/- 53, 160 +/- 5, 184 +/- 20 and 1383 +/- 74 pmol/ml, respectively. The maximum level of each ganglioside decreased gradually, reaching the normal level after 10 days. The half-maximum level of each ganglioside occurred 2-3 days after the administration. Asialo GM1 (GA1) was not detected plasma at any of the test times.