13-week drinking water toxicity study of hydrogen peroxide with 6-week recovery period in catalase-deficient mice.

A GLP OECD guideline study was conducted to evaluate the subchronic toxicity of hydrogen peroxide (HP) when administered continuously in the drinking water of catalase-deficient (C57BL/6N) mice and reversibility of toxic effects. Groups of mice (15/sex/group) received solutions of 0, 100, 300, 1000 or 3000 ppm HP in distilled water for 13 weeks; five/sex/group continued on untreated distilled water for an additional 6 weeks. Animals drinking 3000 ppm HP exhibited depressed water and food consumption and body weight. Females drinking 1000 ppm HP had reduced water consumption with intermittent effects on food consumption, but no body weight effects. HP administration did not produce any mortality, clinical signs, hematological effects or organ weight effects on brain, liver, kidneys, adrenals, testes, heart or spleen. Total protein and globulin were depressed among high dose males. Mild to minimal duodenal mucosal hyperplasia was noted in animals receiving 1000 and 3000 ppm HP and one male receiving 300 ppm for 13 weeks. There were no other histopathological findings. All effects noted during the treatment period, including the duodenal hyperplasia, were reversible during the 6-week recovery period. Females dosed with 300-3000 ppm HP during the treatment period showed increased water consumption during the recovery period. The no-observed-effect level (NOEL), based on duodenal mucosal hyperplasia, is 100 ppm in drinking water or 26 and 37 mg/kg/day HP, respectively, for males and females.     

Toxicology and carcinogenesis studies of acrylamide (CASRN 79-06-1) in F344/N rats and B6C3F1 mice (feed and drinking water studies)

Acrylamide, a water-soluble α,β-unsaturated amide, is a contaminant in baked and fried starchy foods, including french fries, potato chips, and bread, as a result of Maillard reactions involving asparagine and reducing sugars. Additional sources of acrylamide exposure include cigarettes, laboratory procedures involving polyacrylamide gels, and various occupations (e.g, monomer production and polymerization processes). Acrylamide is carcinogenic in experimental animals. To obtain data for developing quantitative risk assessments for dietary exposures to acrylamide, the Food and Drug Administration nominated acrylamide for an in-depth toxicological evaluation by the National Toxicology Program. As part of this evaluation, male and female B6C3F1/Nctr (C57BL/6N x C3H/HeN MTV-) mice and male and female F344/N Nctr rats were exposed to acrylamide (at least 99.4% pure) in drinking water for 2 years. 2-WEEK STUDY IN RATS: Groups of four male and four female F344/N rats were administered 0, 0.14, 0.35, 0.70, 1.41, 3.52, or 7.03 mM acrylamide in the drinking water (0, 10, 25, 50, 100, 250, or 500 ppm acrylamide) or 0.0, 7.4, 18.5, 37, 74, 185, or 370 mg acrylamide per kg diet for 14 days. One male rat administered 7.03 mM acrylamide in the drinking water died on day 14. Male and female rats receiving 7.03 mM acrylamide weighed 56% and 64% of controls, respectively. Male and female rats fed 370 mg acrylamide per kg diet weighed 74% and 83% of controls, respectively. Female rats receiving 3.52 mM acrylamide in drinking water and male rats fed 185 mg acrylamide per kg diet weighed 85% and 89% of controls, respectively. Rats receiving 7.03 mM acrylamide in drinking water or 370 mg acrylamide per kg diet exhibited hind-leg paralysis on day 14. Mild to moderate dilatation of the urinary bladder was observed in all rats given 370 mg acrylamide per kg diet, and in three of four male rats and all four female rats given 7.03 mM acrylamide in drinking water, and in one of four male rats given 3.52 mM acrylamide in drinking water. Mild to moderate degeneration of the germinal epithelium in the seminiferous tubules of the testes was noted microscopically in all male rats given 7.03 mM acrylamide in drinking water and in two of four male rats fed 370 mg acrylamide per kg diet. 2-WEEK STUDY IN MICE: Groups of four male and four female B6C3F1 mice were administered 0, 0.14, 0.35, 0.70, 1.41, 3.52, or 7.03 mM acrylamide in the drinking water (0, 10, 25, 50, 100, 250, or 500 ppm acrylamide) or 0.0, 7.4, 18.5, 37, 74, 185, or 370 mg acrylamide per kg diet for 14 days. None of the mice administered 7.03 mM acrylamide in the drinking water survived the 14-day study. Mice administered 7.03 mM acrylamide in the drinking water showed marked decreases in body weight (greater than 25% compared to control mice) after seven days of treatment, and two of the mice displayed hind leg paralysis. No significant adverse effects were observed in mice administered 3.52 mM acrylamide in the drinking water for 14 days. Female B6C3F1 mice given 370 mg acrylamide per kg diet for 14 days showed a modest decrease (11%) in body weight. No other significant adverse effects were observed in mice administered any dose of acrylamide in the diet. 3-MONTH STUDY IN RATS: Groups of eight male and eight female F344/N rats were administered 0.0, 0.14, 0.35, 0.70, 1.41, or 3.52 mM acrylamide in the drinking water (0, 10, 25, 50, 100, or 250 ppm acrylamide) or 0.0, 7.4, 18.5, 37, 74, or 185 mg acrylamide per kg diet for 13 weeks. After 13 weeks, male and female rats administered 3.52 mM acrylamide weighed 73% and 71% of the control rats, respectively. Male and female rats fed 185 mg acrylamide per kg diet for 13 weeks weighed 86% and 82% of the control rats, respectively. Hind-leg paralysis was observed in all rats administered 3.52 mM acrylamide in the drinking water or 185 mg acrylamide per kg diet. Four of eight female rats administered 1.41 mM acrylamide also displayed hind-leg paralysis. Radiculoneuropathy (a degenerative lesion) involving the sciatic nerve and lumbar spinal cord was observed in all male and female rats administered 3.52 mM acrylamide or 185 mg acrylamide per kg diet. A low incidence of radiculoneuropathy was also noted in female rats fed 74 mg acrylamide per kg diet. The neuronal degenerative changes were accompanied, at times, by atrophy in skeletal muscle of the hind-limb and luminal dilation of the urinary bladder. All rats treated with 3.52 mM acrylamide displayed increased hemosiderin pigment in their spleens and hyperplasia of red blood cell precursors in their bone marrow. Two of eight male rats fed 185 mg acrylamide per kg diet also had increased hemosiderin pigment in their spleens. Degeneration of the germ cells in the testes was observed in all male rats given 1.41 or 3.52 mM acrylamide, or 185 mg acrylamide per kg diet. A lower incidence of this lesion was also detected in all other doses of acrylamide in the diet. 3-MONTH STUDY IN MICE: Groups of eight male and eight female B6C3F1 mice were administered 0, 0.14, 0.35, 0.70, 1.41, or 3.52 mM acrylamide in the drinking water (0, 10, 25, 50, 100, or 250 ppm acrylamide) or 0.0, 18.5, 37, 74, 185, or 370 mg acrylamide per kg diet. After 13 weeks, the male and female mice given 3.52 mM acrylamide weighed 86% and 94% of their respective control mice; male mice administered 1.41 mM acrylamide weighed 91% of the control male mice; and male and female mice fed 370 mg acrylamide per kg diet weighed 87% and 81% of their respective control groups. Hind-limb paralysis was observed in all mice administered 3.52 mM acrylamide or 370 mg acrylamide per kg diet. Radiculoneuropathy involving the sciatic nerve, lumbar spinal cord, or both was observed in all male and female mice administered 3.52 mM acrylamide. Radiculoneuropathy, involving primarily the sciatic nerve, was also noted in one of eight female mice fed 185 mg acrylamide per kg diet and in mice fed 370 mg acrylamide per kg diet. The neuronal degenerative changes were accompanied, at times, by atrophy in skeletal muscle of the hind-limb and luminal dilation of the urinary bladder. Degeneration of the germ cells in the testes was observed in six of eight male mice given 3.52 mM acrylamide and seven of seven mice fed 370 mg acrylamide per kg diet. 2 YEAR STUDY IN RATS: Groups of 48 male and 48 female F344/N rats were administered acrylamide in the drinking water ad libitum for 2 years. Concentrations of 0.0875, 0.175, 0.35, and 0.70 mM acrylamide (6.25, 12.5, 25, and 50 ppm acrylamide) resulted in an average daily consumption of approximately 0.33, 0.66, 1.32, and 2.71 mg acrylamide per kg body weight in male F344/N rats and 0.44, 0.88, 1.84, and 4.02 mg acrylamide per kg body weight in female F344/N rats. Acrylamide had no effect upon the survival of male F344/N rats. Female F344/N rats administered 0.175, 0.35, or 0.70 mM acrylamide had decreased survival compared to control female F344/N rats. Acrylamide caused significant dose-related decreasing trends in body weight in F344/N rats. At the end of the 2 year period, male and female F344/N rats administered 0.70 mM acrylamide weighed 86% and 85% of their respective control groups. Feed consumption was generally not affected by acrylamide; water consumption in female F344/N rats was increased at later time points. In male F344/N rats, the incidence of epididymis malignant mesothelioma, combined epididymis or testicular tunica malignant mesothelioma, heart malignant incidences of schwannoma, pancreatic islets adenoma, thyroid gland follicular cell carcinoma, and combined thyroid gland follicular cell adenoma or carcinoma was increased significantly in the 0.70 mM acrylamide group. In female F344/N rats, the incidence of clitoral gland carcinoma was increased significantly in the 0.0875, 0.175, and 0.70 mM acrylamide groups. The incidence of mammary gland fibroadenoma was increased significantly at 0.175, 0.35, and 0.70 mM acrylamide. Significant increases in neoplasm incidences were also observed in oral mucosa squamous cell papilloma, combined oral mucosa or tongue squamous cell papilloma or carcinoma, combined skin fibroma, fibrosarcoma, or sarcoma, and combined thyroid gland follicular cell adenoma or carcinoma at 0.70 mM acrylamide. 2-YEAR STUDY IN MICE: Groups of 48 male and 48 female B6C3F1 mice were administered acrylamide in the drinking water ad libitum for 2 years. Concentrations of 0.0875, 0.175, 0.35, and 0.70 mM acrylamide (6.25, 12.5, 25, and 50 ppm acrylamide) resulted in average daily consumption of approximately 1.04, 2.20, 4.11, and 8.93 mg acrylamide per kg body weight in male B6C3F1 mice and 1.10, 2.23, 4.65, and 9.96 mg acrylamide per kg body weight in female B6C3F1 mice. Acrylamide caused dose-related decreasing trends in survival in B6C3F1 mice, with the survival being significantly decreased in male B6C3F1 mice administered 0.70 mM acrylamide and female B6C3F1 mice given 0.35 and 0.70 mM acrylamide. Acrylamide caused only sporadic changes in body weight in B6C3F1 mice, with the magnitude of the change never exceeding 6% of the respective control body weight. Food and water consumption was generally not affected by acrylamide, except for an increased consumption by female B6C3F1 mice in the 0.70 mM acrylamide group toward the end of the study. In male B6C3F1 mice, the incidence of harderian gland adenoma and combined harderian gland adenoma or adenocarcinoma was increased significantly in all acrylamide dose groups. The incidence of lung alveolar/bronchiolar adenoma and combined lung alveolar/bronchiolar adenoma or carcinoma was increased significantly at 0.175 and 0.70 mM acrylamide, and the incidence of stomach (forestomach) squamous cell papilloma and combined stomach (forestomach) squamous cell papilloma or carcinoma was increased significantly at 0.35 and 0.70 mM acrylamide. (ABSTRACT TRUNCATED)     

Toxicity and carcinogenicity of rotenone given in the feed to F344/N rats and B6C3F1 mice for up to two years

Toxicity and carcinogenicity studies of rotenone were conducted in F344/N rats and B6C3F1 mice. Groups of 50 rats and 50 mice of each sex were given rotenone in their diet for up to 103 weeks. The doses were 0, 38, and 75 ppm for rats and 0, 600, and 1,200 ppm for mice. Reduction in body weight gain occurred in male and female mice given rotenone. No effects on survival were observed for rats of either sex or female mice. Survival of male mice at 1,200 ppm was significantly greater than that of controls (47/50 vs. 29/50). There were no observed nonneoplastic effects due to rotenone, and for male and female mice no neoplasms were induced by rotenone. Parathyroid adenomas occurred at a higher incidence (4/44) in male rats at 75 ppm than in the controls (1/41). Because these tumors are rare (historical rate in NTP studies is 0.3%), the increase in the incidence of these benign tumors may have been related to rotenone administration. Hepatocellular neoplasms were reduced (p less than 0.01) in males receiving 1,200 ppm 1/50 relative to controls 12/47. Because this low rate of liver tumors is unusual in male B6C3F1 mice, this decrease was considered to be related to rotenone administration.     

Suppressive effects of chlorogenic acid on N-methyl-N-nitrosourea-induced glandular stomach carcinogenesis in male F344 rats

The modifying effects of chlorogenic acid (CA) on N-methyl-N-nitrosourea (MNU)-induced glandular stomach carcinogenesis were investigated in five groups of male F344 rats. Rats in Groups 1 through 3 were given MNU in drinking water at a concentration of 400 ppm for 12 weeks. Animals of Group 1 were then kept on the basal diet alone, and those of Group 2 or 3 were fed a diet containing 500 or 250 ppm CA for a subsequent 22 weeks. Group 4 was exposed to CA alone through the experimental period (36 weeks), and Group 5 was given the basal diet continuously and treated as a control. At the end of the experiment, the incidence of glandular stomach carcinoma of Group 3 was significantly smaller than that of Group 1 (p < 0.03). The incidence of adenomatous hyperplasia of Group 2 was also significantly lower than that of Group 1 (p < 0.02). In addition, the proliferating cell nuclear antigen (PCNA) labeling index of the epithelial cells from the non-neoplastic mucosa in rats of Group 2 or 3 was significantly smaller than that of Group 1 (p < 0.0001). These results suggest that CA has a chemopreventive effect on MNU-induced rat glandular stomach carcinogenesis by exposure during the post-initiation phase, and CA may be a promising agent for prevention of human stomach cancer.     

Short-term toxicity of allyl alcohol in rats

Groups of 15 male and 15 female rats were give 0 (control), 50, 100, 200 or 800 ppm allyl alcohol in the drinking water for 15 weeks. There were no effects attributable to allyl alcohol in the results of the haematological examinations or analyses of serum. There was a dose-related reduction in the fluid intake at all treatment levels in both sexes, while growth and food consumption were reduced in both sexes given 800 ppm and in males give 200 ppm. Males given 100 ppm or above and females given 200 or 800 ppm produced less urine than the controls in a period without water or following a water load. The only changes in organ weight that could be attributed to treatment were increased values for the relative weights of liver, spleen and kidney. All 3 organs were affected in both sexes given 800 ppm and the kidneys were also affected in both sexes given 200 ppm and in females given 100 ppm. No effects attributable to allyl alcohol treatment were seen at autopsy or in the histopathological examination. The no-untoward-effect level established in this study was 50 ppm of the drinking water, a level equivalent to an intake in rats of between 4.8 and 6.2 mg allyl alcohol/kg/day.     

Antioxidant and lipid peroxidation activities in rats fed with Aspergillus carbonarius carotenoid

Effect of feeding partially saturated canthaxanthin (PSC), purified from Aspergillus carbonarius mutant, was studied using four groups of female albino rats (n = 6) for 4 weeks. While the control group received basal diet ad libitum, Groups I, II and III were fed with basal diet containing 50, 100 and 250 ppm PSC, respectively. PSC feeding did not cause any significant changes in food intake and there was no gain in body weight either. PSC included in the diet significantly decreased cholesterol in blood. There was 44.75% and 60.54% decrease in LDL-cholesterol in rats fed with 50 and 100 ppm carotenoid. Hepatic ascorbic acid content increased by 44.59% in rats fed with 50 ppm PSC. Dietary PSC at 250 ppm lowered lipid peroxides by 19.49%. Activities of antioxidant enzymes, glutathione transferase and catalase were significantly higher in serum and liver of PSC fed rats compared to the controls. The results suggested that PSC feeding can induce hypocholesterolmic and antioxidant properties in rats.     

Toxicity and Carcinogenicity of Rotenone Given in the Feed to F344/N Rats and B6C3F1 Mice for up to Two Years

ABSTRACT

Toxicity and carcinogenicity studies of rotenone were conducted in F344/N rats and B6C3F1 mice. Groups of 50 rats and 50 mice of each sex were given rotenone in their diet for up to 103 weeks. The doses were 0, 38, and 75 ppm for rats and 0, 600, and 1,200 ppm for mice. Reduction in body weight gain occurred in male and female mice given rotenone. No effects on survival were observed for rats of either sex or female mice. Survival of male mice at 1,200 ppm was significantly greater than that of controls (47/50 vs. 29/50). There were no observed nonneoplastic effects due to rotenone, and for male and female mice no neoplasms were induced by rotenone. Parathyroid adenomas occurred at a higher incidence (4/44) in male rats at 75 ppm than in the controls (1/41). Because these tumors are rare (historical rate in NTP studies is 0.3%), the increase in the incidence of these benign tumors may have been related to rotenone administration. Hepatocellular neoplasms were reduced (p<0.01) in males receiving 1,200 ppm 1/50 relative to controls 12/47. Because this low rate of liver tumors is unusual in male B6C3F1 mice, this decrease was considered to be related to rotenone administration.     

Subchronic Inhalation Studies of Styrene in CD Rats and CD-1 Mice

Groups of 10 male and 10 female Charles River (CRL) CD (Sprague-Dawley-derived)rats were exposed to styrene vapor at 0, 200, 500, 1000, or1500 ppm 6 hr per day 5 days per week for 13 weeks. Styrenehad no effect on survival, hematology, or clinical chemistry.Males at 1500 ppm weighed 10% less after 13 weeks and malesand females at 1000 and 1500 ppm consumed more water than controls.Histopathologic changes were confined to the olfactory epitheliumof the nasal mucosa. Groups of 20 male and 20 female CRL CD-1and B6C3F1 mice were exposed to styrene vapor at 0, 15, 60,250, or 500 ppm 6 hr per day 5 days per week for 2 weeks. Mortalitywas observed in both CD-1 and B6C3F1 mice exposed to 250 or500 ppm; more female mice, but not males, died from exposureto 250 ppm than from 500 ppm. Groups of 10 male and 10 femaleCRL CD-1 mice were exposed to styrene vapors at 0, 50, 100,150, or 200 ppm 6 hr per day 5 days per week for 13 weeks. Twofemales exposed to 200 ppm died during the first week. Livertoxicity was evident in the decedents and in some female survivorsat 200 ppm. Changes were observed in the lungs of mice exposedto 100, 150, or 200 ppm and in the nasal passages of all treatmentgroups, those exposed to 50 ppm being less affected. Satellitegroups of 15 male rats and 30 male mice were exposed as describedabove for 2, 5, or 13 weeks for measurement of cell proliferation(BrdU labeling). No increase in cell proliferation was foundin liver of rats or mice or in cells of the bronchiolar or alveolarregion of the lung of rats. No increase in labeling index oftype II pneumocytes was seen in mouse lungs, while at 150 and200 ppm, an increased labeling index of Clara cells was seenafter 2 weeks and in occasional mice after 5 weeks. Large variationsin the labeling index among animals emphasize the need for largegroup sizes. For nasal tract effects, a NOAEL was not foundin CD-1 mice, but in CD rats, the NOAEL was 200 ppm. For othereffects, the NOAEL was 500 ppm in rats and 50 ppm in mice.     

Acute, subchronic and chronic toxicity studies of a synthetic antioxidant, 2,2'-isobutylidenebis(4,6-dimethylphenol) in rats

General toxicity studies on 2,2'-isobutylidenebis(4,6-dimethylphenol)(IBBMP) were conducted using male and female Wistar rats. In the acute test, the oral LD50 values were 119 mg/kg BW in males and 103 mg/kg BW in females. Hypersensitivity, loss of righting reflex and abdominal position were observed. In the subchronic test, rats were fed a diet containing IBBMP at levels of 0, 20, 100 or 500 ppm for 13 weeks with interim sacrifice at 4 weeks (equal to 0, 1.1, 5.5 or 27.9 mg/kg BW/day in males and 0, 1.1, 5.9 or 29.6 mg/kg BW/day in females). In both sexes, there were no changes in general condition, body weight gains and food intakes in all groups. No deaths were observed in all groups. Significant increase in AST was observed in 500 ppm males at Week 4. However, the change was not observed at Week 13. Slight but significant decreases in creatinine were also observed in 100 ppm females at Week 13 and 500 ppm males and females at Weeks 4 and 13. Total cholesterol (T-CHO) was significantly elevated in females of the 500 ppm group at Weeks 4 and 13. Absolute and relative liver weights were increased in 500 ppm of both sexes at Week 4. In females, the increases were also observed at Week 13. However, no remarkable histopathological findings were observed in all treated groups. In the chronic test, rats were fed a diet containing IBBMP at levels of 0, 100, 500 and 1500 ppm for 18 months with interim sacrifices at 6 and 12 months (equal to 0, 3.8, 19.4 or 59.4 mg/kg BW/day in males and 0, 4.3, 20.9 or 67.5 mg/kg BW/day in females). No remarkable changes in general appearance were observed in any rats. Body weight gains, food intakes and survival rates in all treated animals were comparable to those of the control. No remarkable changes in the hematological parameters were observed. T-CHO was significantly elevated in females of the 1500 ppm groups throughout the experiment. Significant increases or tendencies for increase in relative liver weights were observed in the 500 and 1500 ppm animals of both sexes. Increased incidences of swelling in liver cells were observed in 1500 ppm males at 6 months and 1500 ppm females at 12 and 18 months. At 18 months, dose-dependent increases in thickness of basement membrane of renal tubules and Bowman's capsule and cell infiltration to the interstitium of the kidney were observed in males. Significant increases of hyaline cast and basophilic change were also observed in 1500 ppm males. In females, increased incidences of hyaline cast were observed at 500 ppm and higher at 18 months. No other toxicity was apparent. No neoplastic lesions that could be attributed to IBBMP were observed in any organs of either sex. From the result of the chronic toxicity test, the no-observed-adverse-effect level (NOAEL) for IBBMP was concluded to be 100 ppm in the diet (4.26 mg/kg BW/day) in female rats on the basis of induction of hyaline cast in renal tubules at 500 ppm, whereas, in males, only a lowest-observed-adverse-effect level (LOAEL) was given as 100 ppm (3.84 mg/kg BW/day) on the basis of induction of thickening of basement membrane in renal tubules at 100 ppm.     

Ascorbic acid deficiency aggravates stress-induced gastric mucosal lesions in genetically scorbutic ODS rats

We examined whether ascorbic acid (AA) deficiency aggravates water immersion restraint stress (WIRS)-induced gastric mucosal lesions in genetically scorbutic ODS rats. ODS rats received scorbutic diet with either distilled water containing AA (1 g/l) or distilled water for 2 weeks. AA-deficient rats had 12% of gastric mucosal AA content in AA-sufficient rats. AA-deficient rats showed more severe gastric mucosal lesions than AA-sufficient rats at 1, 3 or 6 h after the onset of WIRS, although AA-deficient rats had a slight decrease in gastric mucosal AA content, while AA-sufficient rats had a large decrease in that content. AA-deficient rats had more decreased gastric mucosal nonprotein SH and vitamin E contents and increased gastric mucosal lipid peroxide content than AA-sufficient rats at 1, 3 or 6 h of WIRS. These results indicate that AA deficiency aggravates WIRS-induced gastric mucosal lesions in ODS rats by enhancing oxidative damage in the gastric mucosa. Received 12 July 2006; accepted 21 August 2006     

蛭龙活血通瘀胶囊对阿司匹林抵抗大鼠模型的干预及机制探讨

目的:建立阿司匹林抵抗(AR)的动物模型,观察蛭龙活血通瘀胶囊对AR大鼠的治疗作用,并探讨其可能机制。方法:采用高脂高糖高盐饲料(普通饲料70.8%,猪油15%,蔗糖10%,胆固醇0.2%,食盐4%),喂养12周,同时9～12周灌胃给药[2.68 mg·(100 g)^-1·d^-1阿司匹林+3.57 mg·(100 g)^-1·d^-1布洛芬],以建立AR大鼠模型。血栓弹力图(TEG)评价AR造模情况。造模成功后,分为模型组、蛭龙活血通瘀胶囊治疗组、氯吡格雷治疗组,同时设正常组,按实验计划进行对应药物及蒸馏水灌胃治疗。4周后,检测各组大鼠血脂变化、花生四烯酸(aa)诱导途径的最大幅度MA(aa)值、血栓素B₂(TXB₂)和6-酮-前列腺素F1a(6-keto-PGF1a)含量、miRNA-126的表达。结果:(1)造模12周后,与正常组比较,模型组大鼠MA(aa)值显著增加(P<0.05)。(2)治疗4周后,与模型组比较,蛭龙活血通瘀胶囊治疗组和氯吡格雷治...     

N-亚硝基二乙胺(DEN)诱导SD大鼠肝癌模型的研究

目的 建立与人类的肝癌发生发展过程相似的动物模型,以便研究肝癌的发生发展过程。方法 取体质量120~150 g雄性SD大鼠65只,适应环境1周后随机分为实验组(50只)和对照组(15只),实验组饮用含N-亚硝基二乙(DEN)(浓度为76 ppm)(以下简称DEN)的水连续6周后停药,改自由饮水3周,再继续饮用含DEN(76 ppm)的水至20周。对照组常规自由饮水。结果 病理学检查证实DEN可诱发大鼠形成肝癌,14周后成癌率为66.7%(10/15),大鼠肝癌的癌变过程大致可分为肝炎期、肝硬化期和肝癌期三个发展阶段。结论 饲以76 ppm剂量DEN可诱发大鼠肝癌模型的建立,可以为我们研究大鼠肝癌的发生发展过程提供可靠的动物模型。     

Toxicology and carcinogenesis studies of divinylbenzene-HP (Cas No. 1321-74-0) in F344/N rats and B6C3F1 mice (inhalation studies)

Divinylbenzene-HP is used for producing vinyl polymers. Divinylbenzene-HP was nominated for study by the National Cancer Institute because of the potential for worker exposure and the structural similarity of divinylbenzene to styrene, a potential human carcinogen. Male and female F344/N rats and B6C3F1 mice were exposed to divinylbenzene-HP (80%) by inhalation for 2 weeks, 3 months, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Escherichia coli, and mouse peripheral blood erythrocytes. 2-WEEK STUDY IN RATS: Groups of five male and five female rats were exposed by whole body inhalation to divinylbenzene-HP at target concentrations of 0, 25, 50, 100, 200, or 400 ppm 6 hours plus T90 (12 minutes) per day, 5 days per week for 16 days. All rats survived to the end of the study. Significant decreases in mean body weights occurred in both male and female rats in the 400 ppm groups. Relative kidney weights of 50 ppm or greater males and relative liver weights of 200 and 400 ppm males were significantly greater than those of the chamber controls. A clear serous nasal/eye discharge was observed in groups of males exposed to 100 ppm or greater and females exposed to 50 ppm or greater. Minimal or mild rhinitis occurred in 400 ppm rats of both sexes. 2-WEEK STUDY IN MICE: Groups of five male and five female mice were exposed by whole body inhalation to divinylbenzene-HP at target concentrations of 0, 25, 50, 100, 200, or 400 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for 17 days. All 400 ppm males and females died on or before the second day of the study, and two male and two female 200 ppm mice died early. Mean body weights of 100 and 200 ppm males were significantly less than those of the chamber controls. Thymus weights of exposed groups of males were significantly less than those of the chamber controls, and relative liver weights of 100 and 200 ppm males were significantly increased. Kidney and liver weights of exposed groups of females were significantly greater than those of the chamber controls. Mice exposed to 200 and 400 ppm had liver lesions including degeneration, necrosis, hemorrhage or cytomegaly. Renal tubule necrosis and regeneration occurred at 200 ppm. Necrosis or metaplasia of nasal epithelium and glands occurred in the nose in all exposure groups. 3-MONTH STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to divinylbenzene-HP at concentrations of 0, 25, 50, 100, 200, or 400 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. All rats survived to the end of the study. There were no biologically significant changes in body weight in either sex. Nasal/eye discharge was noted in 400 ppm males and 100 ppm females. Kidney and liver weights of exposed groups of males and of 400 ppm females were generally greater than those of the chamber controls. In addition, the relative weights of the heart and testis were significantly increased in 200 and 400 ppm males. Incidences of degeneration of the olfactory epithelium in 200 and 400 ppm rats and basal cell hyperplasia of the olfactory epithelium in rats exposed to 100 ppm or greater were significantly increased. 3-MONTH STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to divinylbenzene-HP at concentrations of 0, 12.5, 25, 50, 100, or 200 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. All 200 ppm males and nine 200 ppm females died early. Final mean body weights were significantly lower in males and females exposed to 25, 50, or 100 ppm when compared with chamber controls. Lethargy or hypoactivity was observed in the higher exposure concentration groups. Exposure to divinylbenzene was associated with necrosis of the liver and kidney in 200 ppm males and females dying early. In all exposed groups of male and female mice, there was necrosis of nasal cavity lateral walls, olfactory epithelium, and glands with resultant atrophy of olfactory epithelium and glands in females. A lower number of animals had necrotic or degenerative changes of the upper respiratory tract. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to divinylbenzene-HP at concentrations of 0, 100, 200, or 400 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for up to 105 weeks. Survival of 400 ppm females was significantly less than that of the chamber control group. Survival of all exposed groups of males was similar to that of the chamber control group. Mean body weights of 400 ppm males and females were significantly less than those of the controls during the second half of the study. Renal tubule carcinomas occurred in two of 50 males exposed to 400 ppm in the original kidney sections, an incidence that exceeded the historical control range. In 400 ppm males, the incidence of renal tubule hyperplasia was increased, and the incidence of nephropathy was significantly increased. Following combined analysis of single and step-section data, the incidences of renal tubule adenoma and adenoma or carcinoma (combined) were marginally higher in 200 and 400 ppm males, and the incidence of renal tubule hyperplasia was significantly increased in 400 ppm males. The incidences of malignant glial cell tumors (malignant astrocytoma and oligodendroglioma) in the brain were slightly increased in 100 and 200 ppm males, and the incidence in the 200 ppm group exceeded the historical range for chamber controls. There were increased incidences of degenerative and regenerative changes in the olfactory epithelium in the nose of all exposed groups of rats. The incidence of focal chronic inflammation in the lung of 400 ppm males was significantly greater than in the chamber control group. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to divinylbenzene-HP at concentrations of 0, 10, 30, or 100 ppm for 6 hours plus T90 (12 minutes) per day, 5 days per week for up to 105 weeks. Survival of all exposed groups of male and female mice was similar to that of the chamber controls. Mean body weights were lower relative to chamber controls in 100 ppm males and in 30 and 100 ppm females. The incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) in 100 ppm males were greater than chamber control incidences, but the incidences of adenoma or carcinoma (combined) were within the historical control range. The incidences of alveolar/bronchiolar adenoma and alveolar/bronchiolar adenoma or carcinoma (combined) in all exposed groups of females were generally greater than those of the chamber controls; the incidences were at the upper end or exceeded the historical control ranges. There was a greater incidence and severity of alveolar epithelial hyperplasia in 100 ppm females and a greater severity of this lesion in 30 ppm females, when compared to chamber controls. The incidences and/or severities of atypical bronchiole hyperplasia were significantly increased in all exposed groups of mice. Nonneoplastic nasal lesions occurred in most exposed mice. GENETIC TOXICOLOGY: Divinylbenzene-HP was not mutagenic in any of three independent gene mutation assays using Salmonella typhimurium strains TA97, TA98, TA100, TA1535, or TA1537 or Escherichia coli tester strain WP2 uvrA with or without induced hamster or rat liver enzymes. No increases in the frequencies of micronucleated normochromatic erythrocytes or alterations in the percentages of polychromatic erythrocytes were seen in peripheral blood of male or female B6C3F1 mice exposed to divinylbenzene-HP by inhalation for 3 months. CONCLUSIONS: Under the conditions of this 2-year inhalation study, there was equivocal evidence of carcinogenic activity of divinylbenzene-HP in male F344/N rats based upon the occurrence of carcinomas in the kidney and glial tumors in the brain. There was no evidence of carcinogenic activity in female F344/N rats exposed to 100, 200, or 400 ppm divinylbenzene-HP. There was no evidence of carcinogenic activity in male B6C3F1 mice exposed to 10, 30, or 100 ppm divinylbenzene-HP. There was equivocal evidence of carcinogenic activity of divinylbenzene-HP in female B6C3F1 mice based on the incidences of alveolar/bronchiolar adenoma or carcinoma (combined) in the lung. Exposure to divinylbenzene-HP caused nonneoplastic lesions of the nasal cavity in male and female rats and of the lung and nasal cavity in male and female mice.     

Lack of promotion activity of diacylglycerol oil on 4-nitroquinoline 1-oxide induced carcinogenesis in the oral cavity of SD rats

A recent study using c-Ha-ras proto-oncogene transgenic (rasTg) rats demonstrated possible enhancing effects of diacylglycerol (DAG) on 4-nitroquinoline 1-oxide (4NQO) induced carcinogenesis of the tongue. To assess effects in their Sprague-Dawley back strain, a two-stage carcinogenesis study using 4NQO as an initiator was performed. Groups of 30 male rats were initially treated with 4NQO at a dose of 10ppm in the drinking water for the first 10 weeks followed after a 1 week recovery interval by 11% DAG, 5.5% DAG+5.5% triacylglycerol (TAG), 2.75% DAG+8.25% TAG, 1.38 DAG+9.62% TAG, 11% TAG, 11% high linoleic acid TAG (HLTG), 5.5% DAG or 2.75% DAG in the diet for 35 weeks. Further groups of animals were treated with distilled water instead of 4NQO followed by 11% DAG, 11% TAG or 11% HLTG in the same manner. The final survival rates in 4NQO-treated groups were from 50 to 77%. However, incidences and multiplicities of squamous cell papillomas and carcinomas in the oral cavity induced by 4NQO were not affected by any of the dietary treatments. Thus, in contrast to the positive data using rasTg rats, DAG had no potential for enhancing 4NQO-induced tumorigenesis in their back strain.     

Effect of growth hormone on epiphyseal growth plates in zinc deficiency

This study was carried out on 18 albino rats. The control group, consisting of six rats, was fed a normal diet and tap water. The other rats were given a zinc-deficient diet and deionized water. Two weeks later the latter group was again divided into two into smaller groups. The first of these groups was given an given an additional 100 ppm of zinc acetate. From the fifteenth day onwards, the human growth hormone (Nanormon) was injected intra-peritoneally to each group at a dose of 80 micrograms/day for two weeks. At the end of the experiment, it was found that body weights were markedly increased in the control and zinc-added groups compared with the zinc-deficient rats. In the zinc-deficient group, serum zinc, hair zinc levels, alkaline phosphatase activity and serum protein levels were lower than those of the control and zinc-added groups. The zinc-deficient group had narrower tibial epiphyseal growth plates than those of the control group. The count of hypertrophied cells was also less in the zinc-deficient group. Based on these data, our conclusion was that the growth hormone becomes ineffective under conditions of zinc deficiency. This means that zinc deficiency has multidimensional effects on growth hormone activity.     

Dose-dependent induction of carcinomas and glutathione S-transferase placental form negative eosinophilic foci in the rat liver by di(2-ethylhexyl)phthalate after diethylnitrosamine initiation.

The dose-dependence of di(2-ethylhexyl)phthalate (DEHP) hepatocarcinogenicity was investigated in male F344 rats which were initially injected with diethylnitrosamine (200 mg/kg, i.p.) and subjected to partial hepatectomy at week 3. The animals were administered DEHP in the diet at concentrations of 30, 300, 3,000, or 12,000 ppm starting 2 weeks after the DEN injection for up to 46 weeks and killed at weeks 8, 24, 48 and 52. Additional groups were given clofibrate (3,000 ppm in diet) or basal diet instead of the DEHP diet. Incidences of hepatocellular carcinomas were 75% (9/12, P < 0.01) for 12,000 ppm, 10% (1/10) for 3,000 ppm, 7% (1/14) for 300 ppm, 0% (0/13) for 30 ppm, 15% (2/13) for clofibrate, and 8% (1/13) for the basal diet group at week 52, 4 weeks after cessation of chemical feeding. Development of glutathione S-transferase placental form (GST-P) positive foci was only slightly increased by clofibrate-administration at week 52 and consistently lower than the control level in the DEHP-treated groups after 24 weeks. In contrast, GST-P negative eosinophilic foci were dose-dependently increased in the more than 300 ppm DEHP and clofibrate treated groups. At the 30 ppm dose level, however, no morphological changes were apparent in the liver. Thus, the non-observed effect level regarding the promotional activity of hepatocarcinogenesis was demonstrated at 30 ppm, the effects being predictable on the basis of development of GST-P negative eosinophilic foci.     

Toxicology and carcinogenesis studies of p,p'-dichlorophenyl sulfone (CAS No. 80-07-9) in F344/N rats and B6C3F1 mice (feed studies)

p,pN-Dichlorodiphenyl sulfone is used as a starting material in the production of polysulfones and polyethersulfones and as a component in reactive dyes in the textile industry; it is also a by-product of pesticide production. p,pN-Dichlorodiphenyl sulfone was nominated for study by the National Cancer Institute because of its history of high production and use, the prospect of increased production and use, and the absence of adequate toxicity testing. Male and female F344/N rats and B6C3F1 mice were exposed top,pN-dichlorodiphenyl sulfone (greater than 99% pure)in feed for 14 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium,cultured Chinese hamster ovary cells, and mouse bone marrow. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were fed diets containing 0, 30, 100, 300, 1,000, or 3,000 ppm p,pN-dichlorodiphenyl sulfone (equivalent to average daily doses of approximately 2, 6, 19, 65, or 200 mgp,pN-dichlorodiphenyl sulfone/kg body weight) for 14 weeks. All rats survived until the end of the study. Mean body weights of groups exposed to 300 ppm or greater were significantly less than those of the controls. Liver weights of groups exposed to 100 ppm or greater and kidney weights of 1,000 and 3,000 ppm male rats were significantly greater than those of the controls. Centrilobular hepatocyte hypertrophy of the liver was observed in most male rats exposed to 100 ppm or greater and in all female rats exposed to 300 ppm or greater, and the severities were increased in 300 ppm males and 1,000 and 3,000 ppm males and females. The incidences of nephropathy in 1,000 and 3,000 ppm female rats were significantly increased. Dose-related increases in severity of nephropathy were observed in male rats. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were fed diets containing 0, 30, 100, 300, 1,000, or 3,000 ppm p,pN-dichlorodiphenyl sulfone (equivalent to average daily doses of approximately 3.5, 15, 50, 165,or 480 mg/kg) for 14 weeks. All mice survived until the end of the study. Mean body weights of groups exposed to 300 ppm or greater were significantly less than those of the controls. Liver weights of groups exposed to 300 ppm or greater were significantly increased. Centrilobular hypertrophy of the liver was observed in most males exposed to 100 ppm or greater and in all females exposed to 1,000 or 3,000 ppm, and the severities generally increased with increasing exposure concentration. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were fed diets containing 0, 10 (males), 30, 100, or 300 (females) ppm p,pN-dichlorodiphenyl sulfone for 105 weeks. Dietary concentrations of 10, 30, and 100 ppm resulted in average daily doses of approximately 0.5, 1.5, and 5.0 mg/kg to males. Dietary concentrations of 30, 100,and 300 ppm resulted in average daily doses of approximately 1.6, 5.4, and 17 mg/kg to females. Additional groups of 10 male and 10 female rats were fed the same p,pN-dichlorodiphenyl sulfone-containing diets for 18 months and bled for plasma determinations of p,pN-dichlorodiphenyl sulfone at approximately 2 weeks and 3, 12, and 18 months. Survival of all exposed groups of male and female rats was similar to that of the control groups. Mean body weights of 30 and 100 ppm males were generally less than those of the controls during the latter part of the study, and mean body weights of 100 and 300 ppm female rats were less from weeks 30 and 18,respectively. Feed consumption by the exposed groups was similar to that by the controls throughout the study. The incidences of centrilobular hepatocyte hypertrophy in 100 ppm male and 100 and 300 ppm female rats were significantly greater than those in the controls. The incidences of bile duct hyperplasia and centrilobular degeneration were also significantly increased in 100 and 300 ppm females. No neoplasms were related to chemical exposure. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were fed diets containing 0, 30, 100, or 300 ppm p,pN-dichlorodiphenyl sulfone for 105 to 106 weeks. Dietary concentrations of 30, 100, and 300 ppm delivered average daily doses of approximately 4, 13, and 40 mg/kg to males and approximately 3, 10, and 33 mg/kg to females. Additional groups of 10 male and 10 female mice were fed the same p,pN-dichlorodiphenyl sulfone-containing diets for up to 12 months;three mice in each group were bled for plasma determinations of p,pN-dichloro-diphenyl sulfone at approximately 2 weeks or 3 or 12 months. Survival of all exposed groups of male and female mice was similar to that of the control groups. Mean body weights of 300 ppm mice were less than those of the controls throughout most of the study. Feed consumption by the exposed groups was similar to that by the controls throughout the study. The incidences of centrilobular hepatocyte hypertrophy in all exposed groups of male mice and in 100 and 300 ppm females were significantly greater than those in the controls. The incidence of eosinophilic foci in 300 ppm females was significantly increased. No neoplasms were related to chemical exposure. PHARMACOKINETICS OF p,pN-DICHLORODIPHENYL SULFONE: p,pN-Dichlorodiphenyl sulfone is rapidly absorbed from the gut and metabolized by a saturable process. Although some p,pN-dichlorodiphenyl sulfone is eliminated unchanged in feces and urine, most of the elimination is via metabolism. Mathematical modeling of the toxicokinetics supports the view that p,pN-dichlorodiphenyl sulfone induces enzymes involved in its metabolism. GENETIC TOXICOLOGY: p,pN-Dichlorodiphenyl sulfone was not mutagenic in any of several strains of Salmonella typhimurium, with or without metabolic activation enzymes (S9). Results of the sister chromatid exchange test in cultured Chinese hamster ovary cells were judged to be negative in the presence of S9 and equivocal in the absence of S9, but no induction of chromosomal aberrations was noted, with or without S9. In contrast to the in vitro results, positive results were obtained in an acute in vivo mouse bone marrow micronucleus assay with p,pN-dichlorodiphenyl sulfone administered by intraperitoneal injection three times over a dose range of 200 to 800 mg/kg. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity* of p,pN-dichlorodiphenyl sulfone in male F344/N rats exposed to 10, 30, or 100 ppm or in female F344/N rats exposed to 30, 100, or 300 ppm. There was no evidence of carcinogenic activity of p,pN-dichlorodiphenyl sulfone in male or female B6C3F1 mice exposed to 30,100, or 300 ppm. Exposure to p,pN-dichlorodiphenyl sulfone for 2 years caused increased incidences of nonneoplastic lesions of the liver in male and female rats and mice.     

NTP toxicology and carcinogenesis studies of decalin (CAS No. 91-17-8) in F344/N rats and B6C3F(1) mice and a toxicology study of decalin in male NBR rats (inhalation studies)

Decalin is used as an industrial solvent for naphthalene, fats, resins, oils, and waxes. It is also used as a substitute for turpentine in lacquers, paints, and varnishes; as a solvent and stabilizer for shoe polishes and floor waxes; and as a constituent of motor fuels and lubricants. Other applications include use as a paint thinner and remover, a patent fuel in stoves, a high-density fuel in submarine-launched cruise missile systems, and in stain removal and cleaning machinery. Decalin was nominated for study by the National Cancer Institute because of its chemical structure, its potential for consumer exposure, and a lack of adequate testing of the chemical. Male and female F344/N rats and B6C3F(1) mice were exposed to decalin (greater than 99% pure) by inhalation for 2 weeks, 3 months, or 2 years. Groups of male NBR rats were exposed to decalin for 2 weeks. Male NBR rats do not produce alpha2u-globulin; the NBR rats were included to study the relationship of alpha2u-globulin and renal lesion induction. Genetic toxicology studies were conducted in Salmonella typhimurium and mouse peripheral blood erythrocytes. 2-WEEK STUDIES IN RATS: Groups of five male and five female F344/N rats and five male NBR rats were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 16 days. All rats survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber controls. Renal toxicity studies were performed in male F344/N and NBR rats. The numbers of labeled cells and the labeling indices in the left kidney of 200 and 400 ppm F344/N male rats were significantly greater than those in the chamber controls. The alpha2u-globulin/soluble protein ratios were significantly increased in all exposed groups of F344/N rats. Liver weights of male F344/N and NBR rats exposed to 100 ppm or greater were significantly increased, as were those of all exposed groups of females. Kidney weights of male F344/N rats exposed to 50 ppm or greater were significantly increased. Exposure-related hyaline droplet accumulation, degeneration and regeneration of renal cortical tubules, and granular casts occurred in the kidney of exposed F344/N male rats. 2-WEEK STUDIES IN MICE: Groups of five male and five female B6C3F(1) mice were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 17 days. All mice survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Liver weights of 200 and 400 ppm males and females and 100 ppm females were significantly increased. 3-MONTH STUDY IN RATS: Groups of 25 male and 20 female F344/N rats were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 2 (five male renal toxicity rats), 6 (10 male and 10 female clinical pathology rats), or 14 (10 core study rats) weeks. All rats survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Urinalysis results indicated that decalin exposure caused increases in urine glucose and protein concentrations and enzyme activities that were consistent with the renal lesions observed microscopically. Renal toxicity studies were performed on rats sacrificed at 2 and 6 weeks and at the end of the study. In kidney tissue examined for cell proliferation, the numbers of PCNA-labeled cells and labeling indices were generally significantly greater than those of the chamber controls in exposed groups of rats at all three time points. Concentrations of alpha2u-globulin in the kidney as well as the alpha2u-globulin/soluble protein ratios were significantly increased at week 2 in all exposed groups and in the 200 and 400 ppm groups at week 6 and at the end of the study. Absolute and/or relative kidney and liver weights of male rats exposed to 50 ppm or greater were increased. Incidences of renal tubule regeneration and granular casts in the medulla of the kidney in exposed male rats were increased, and the severities of hyaline droplets generally increased with increasing exposure concentration. 3-MONTH STUDY IN MICE: Groups of 10 male and 10 female B6C3F(1) mice were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 14 weeks. All mice survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Liver weights of 200 and 400 ppm males and females were significantly increased. There was a significant exposure concentration-related decrease in the absolute spermatid head count and a significant decrease in absolute head count of the 400 ppm group compared to the chamber controls. Incidences of centrilobular cytomegaly of the liver were increased in exposed male mice. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 25, 50 (male rats only), 100, or 400 ppm (female rats only) decalin vapor 6 hours per day, 5 days per week for 105 weeks. A group of 20 male rats was exposed to 400 ppm. Survival of exposed groups was similar to that of the chamber control groups. Mean body weights of 400 ppm males were slightly less than those of the chamber controls during the second year of the study. Incidences of renal tubule adenoma and adenoma or carcinoma (combined) and of benign or malignant pheochromocytoma (combined) of the adrenal medulla in 100 and 400 ppm males were significantly increased. There was a significant association between nephropathy severity and adrenal pheochromocytoma incidence. Nonneoplastic lesions related to decalin exposure occurred in the kidney of male rats. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F(1) mice were exposed to 0, 25, 100, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 105 weeks. Survival of exposed mice was similar to that of the chamber controls. Mean body weights of exposed groups were generally similar to those of the chamber control groups throughout the study. Increased incidences of hepatocellular neoplasms occurred in 25 and 400 ppm female mice, and the incidences of centrilobular hypertrophy, necrosis, syncytial alteration, and erythrophagocytosis of the liver in 400 ppm males were significantly increased. The incidences of uterine stromal polyp and stromal polyp or stromal sarcoma (combined) occurred with positive trends in female mice. PHARMACOKINETIC MODEL: The rate of metabolism of decalin was the same for males and females in rats and mice. Also in rats and mice, decalin metabolism was saturated at less than 400 ppm. Increased labeling indices in male rats were likely due to changes related to alpha2u-globulin. GENETIC TOXICOLOGY: Decalin was not mutagenic in S. typhimurium strains TA97, TA98, TA100, or TA1535, with or without induced hamster or rat liver S9 enzymes. A small but significant increase in the frequency of micronucleated normochromatic erythrocytes was noted in male mice exposed to decalin for 3 months; however, no induction of micronuclei was observed in female mice. CONCLUSIONS: Under the conditions of these studies, there was clear evidence of carcinogenic activity of decalin in male F344/N rats based on increased incidences of renal tubule neoplasms. The increased incidences of benign or malignant pheochromocytoma (combined) of the adrenal medulla in male rats were also considered to be exposure related. There was no evidence of carcinogenic activity of decalin in female F344/N rats exposed to 25, 100, or 400 ppm. There was no evidence of carcinogenic activity of decalin in male B6C3F(1) mice exposed to 25, 100, or 400 ppm. There was equivocal evidence of carcinogenic activity of decalin in female B6C3F(1) mice based on marginally increased incidences of hepatocellular and uterine neoplasms. Exposure of male rats to decalin resulted in nonneoplastic lesions of the kidney characteristic of alpha2u-globulin accumulation. Nonneoplastic lesions of the liver were observed in male mice exposed to decalin.     

Modulatory effect of naringenin on N-methyl-N'-nitro-N-nitrosoguanidine- and saturated sodium chloride-induced gastric carcinogenesis in male Wistar rats

Naringenin is a flavanone that is believed to have many biological actions, including as an anti-oxidant, free radical scavenger and an antiproliferative agent. The global incidence of gastric carcinoma is increasing rapidly, more than for any other cancer. Therefore, in the present study, we tested the effects of naringenin on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl) in rats. Male Wistar rats were divided into five groups and treated over a period of 20 weeks as follows: (i) a control group given corn oil (1 mL/rat, p.o.) daily 20 weeks; (ii) 200 mg/kg, p.o., MNNG on Days 0 and 14 with S-NaCl (1 mL/rat) administered twice a week for the first 3 weeks; (iii) 200 mg/kg, p.o., MNNG on Days 0 and 14, with naringenin (200 mg/kg, p.o., daily) treatment for the entire 20 weeks; (iv) 200 mg/kg, p.o., MNNG on Days 0 and 14, with naringenin treatment (200 mg/kg, p.o., daily) initiated from 6 to 20 weeks; (v) 200 mg/kg, p.o., naringenin alone daily for 20 weeks. In Group II rats in which gastric cancer was inducted with MNNG and S-NaCl, there was a significant increase in hydrogen peroxide and lipid peroxidation levels, with decreases in reduced glutathione, oxidized glutathione, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase. In addition, in Group II rats with gastric cancer, there were significant increases in the activity of cytochrome P450, cytochrome b(5) and NADPH cytochrome c reductase, with concomitant decreases in the activity of the phase II enzymes glutathione S-transferase and UDP-glucuronosyl transferase. Naringenin treatment (Groups III and IV) restored enzyme activity to near control levels. These results indicate that naringenin has a chemopreventive action against MNNG-induced gastric carcinoma in experimental rats.     

Studies on arsenic metabolism (XX). Arsenic accumulation in the organs and excretion into the feces and urine of rats chronically poisoned with arsenic (author's transl)

Male and female rats (60 approximately 80 g) of Wistar strain were randomly divided into two groups and were given milk and cereal diets, respectively. Each group was further divided into two groups; one was given the diet containing 100ppm of arsenic trioxide and the other a diet containing "arsenic compound" (100ppm as arsenic trioxide). Each group included five rats of both sexes. A 6-month feeding of the test diet was followed by provision of a normal diet. The accumulated arsenic was excreted almost 100% from the brain and 20 approximately 30% from organs such as kidney, liver, spleen and lung. The arsenic level persisted in tissues in animals on the cereal diet, as compared with those fed the milk diet. There was no significant difference in the accumulation and excretion of arsenic between the groups given arsenic trioxide or "arsenic compound".