Glomerular hyperfiltration with hyperglycemia in the spontaneously diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model.

Glomerular hyperfiltration is observed in an early stage of kidney diseases including diabetic nephropathy. A better understanding of pathophysiological changes in glomerular hyperfiltration is essential for development of new therapies to prevent kidney disease progression. In this study, we investigated glomerular changes including glomerular filtration rate (GFR) and glomerular size in the Spontaneously Diabetic Torii (SDT) fatty rat, an obese type 2 diabetic model, and we also evaluated pharmacological effects of the sodium glucose cotransporter 2 inhibitor dapagliflozin on the renal lesions. Dapagliflozin was administered to SDT fatty rats from 5 to 17 weeks of age. Blood and urinary biochemical parameters were periodically measured. GFR was determined by transdermal GFR monitor at 16 weeks of age and histopathological analysis was performed at 17 weeks of age. SDT fatty rat developed severe hyperglycemia and exhibited pathophysiological abnormalities in the kidney, such as an increased GFR, glomerular hypertrophy and tissue lesions. Dapagliflozin achieved good glycemic control during the experimental period, inhibited the increase in GFR, and improved histopathological abnormalities in tubules. These results suggest that the SDT fatty rat is a useful model for analyzing the pathogenesis of diabetic nephropathy during its early stage and dapagliflozin improves not only hyperglycemia but also glomerular hyperfiltration and tubule lesions in SDT fatty rat.

Toxicological evaluation of L-proline in a 90-day feeding study with Fischer 344 rats.

L-proline (L-Pro) is a non-essential amino acid, and has become widely used as supplements and health foods, recently. A subchronic oral toxicity study of L-Pro was conducted with groups of 10 male and 10 female Fischer 344 rats fed a powder diet containing 0%, 0.625%, 1.25%, 2.5% and 5.0% of L-Pro for 90 days. No treatment-related clinical signs and mortality were noted. We observed no clear treatment-related effects with regard to body weight, food intake or urinalysis data. The average daily water intakes of the treated female groups were significantly increased compared to the controls. The hematology (red blood cell parameter) and serum biochemistry (glucose, blood urea nitrogen, creatinine or uric acid) of the treated male and/or female groups were lower than those of the control groups. However, these changes were lacked dose-dependence, and no abnormalities were found in corresponding pathological findings. In conclusion, the no-observed-adverse-effect-level (NOAEL) for L-Pro was determined to be a dietary dose of 5.0% (2772.9 mg/kg body weight/day for males and 3009.3mg/kg body weight/day for females) under the present experimental conditions.

Toxic effects of l-aspartic acid at high dose levels on kidneys and salivary glands in Fischer 344 rats detected in a 90-day feeding study.

A subchronic oral toxicity study of l-aspartic acid (l-Asp) was conducted with groups of 10 male and 10 female Fischer 344 rats fed a powder diet containing 0%, 0.05%, 1.25%, 2.5% and 5.0% concentrations for 90 days. Serum biochemistry showed treatment-related decreases of blood urea nitrogen, creatinine and uric acid levels in both sexes. In addition, incidences of urinary ketone and protein were significantly increased in treated both sexes, while relative kidney weight was significantly increased in the 5.0% male rat, and regenerative renal tubules with tubular dilation were histopathologically observed in male rats of the 2.5% or greater groups. The observed renal injury was confirmed not to be due to accumulation of alpha2u-globulin. Acinar cell hypertrophy of salivary glands was histopathologically evident in male and female rats of the 2.5% or greater groups. The present results indicate that l-Asp causes toxic effects on kidneys and possibly salivary glands at high dose levels in male and female Fischer 344 rats. Such toxic effects were observed only in animals given 2.5% and/or higher doses of l-Asp. In conclusion, the no-observed-adverse-effect-level (NOAEL) for l-Asp is 1.25% (696.6 mg/kg body weight/day for males and 715.2 mg/kg body weight/day for females) under the present experimental conditions.

Increased oxidative DNA damage in mammary tumor cells by continuous epidermal growth factor stimulation.

BACKGROUND: Growth factors can enhance the malignant potential of tumor cells. To examine the relationship between growth factors and tumor progression, we previously established a weakly malignant cell line, ER-1. We found that a 24-hour exposure of ER-1 cells to epidermal growth factor (EGF) induced malignant properties (tumor progression) that were reversible but that, after a 1-month exposure, these changes were irreversible. In this study, we investigated the irreversible changes induced in ER-1 cells by a 1-month exposure to EGF and the possible involvement of oxidative stress. METHODS: ER-1 cells were treated with EGF (100 ng/mL) for 1 month in the presence or absence of an antioxidant, N-acetylcysteine or selenium, and compared with untreated control ER-1 cells. We assessed tumor progression by measuring intracellular peroxide levels, 8-hydroxydeoxyguanosine (a marker for oxidative DNA damage) levels, in vitro invasiveness, and in vivo tumorigenicity and metastatic ability. All statistical tests are two-sided. RESULTS: After ER-1 cells were treated for 1 month with EGF, levels of intracellular peroxide and 8-hydroxyguanosine in the DNA of treated cells were higher than those in the DNA of control cells, and treated ER-1 cells were more tumorigenic and metastatic in vivo and more invasive in vitro than untreated control cells (all P<.001). Levels of 8-hydroxyguanosine in DNA increased as the length of the EGF treatment increased (P<.001). However, when N-acetylcysteine or selenium was added with EGF for 1 month, levels of intracellular peroxide and 8-hydroxyguanosine in DNA were comparable to those in control cells (r =.795). Both tumorigenicity (P =.008) and metastatic ability (P<.001) decreased after addition of N-acetylcysteine or selenium. CONCLUSION: The irreversible changes caused by continuous EGF stimulation of ER-1 cells result from increased oxidative damage in the DNA, which generates tumor cells with more malignant characteristics.

High incidence of hepatocellular carcinomas induced by a choline deficient L-amino acid defined diet in rats.

The carcinogenicities of a choline deficient L-amino acid defined (CDAA) diet and a semipurified choline deficient diet were comparatively examined. A total of 60 male Fischer 344 rats, 6 weeks old, were divided into 5 experimental groups each consisting of 12 rats. Group 1 received the CDAA diet chronically to the end of the 52-week experiment while Group 2 was given the same diet for the first 24 weeks and then a basal diet for the following 28 weeks. Groups 3, 4, and 5 received a choline supplemented L-amino acid defined diet, the semipurified choline deficient diet, and a semipurified choline supplemented diet, respectively, throughout the experimental period. All surviving rats were subjected to complete macroscopic examination at Week 52. Histopathologically diagnosed hepatocellular carcinomas were induced in Group 1 at an incidence of 100%; multiple metastatic nodules were seen in the lungs of one of the animals. Hepatocellular carcinomas were also induced in Group 4 rats at a significantly lower incidence of 20%. No hepatocellular carcinomas were observed in rats in Groups 2, 3, and 4. The results indicate that the CDAA diet exerts more potent carcinogenicity for the livers of rats than does the semipurified choline deficient diet. However, limited exposure for 24 weeks may have not been sufficient for hepatocellular carcinoma induction by the CDAA diet at Week 52 although a high incidence of hyperplastic nodules and slight cirrhosis were evidence of persistent lesions.

Involvement of 8-hydroxyguanine formation in the initiation of rat liver carcinogenesis by low dose levels of N-nitrosodiethylamine.

The question of whether 8-hydroxyguanine (8-OHG) formation is involved in initiation by low dose levels of N-nitrosodiethylamine (DEN) was addressed using a rat liver model. Male Fischer 344 rats, 6 weeks of age, were administered single i.p. doses of DEN between 0.001 and 100 mg/kg body weight. The 8-OHG levels in liver DNA were measured within 72 h thereafter in randomly selected rats. The remaining rats were given either no further treatment, partial hepatectomy (PH) at hour 4, or PH with i.p. administration of 500 mg/kg body weight of colchicine on days 1 and 3. A selection procedure was performed between weeks 2 and 4, and the initiating activity of DEN was assessed in terms of development of gamma-glutamyltransferase-positive foci at week 5. The 8-OHG levels in the liver DNA were significantly elevated between hours 6 and 72 in a manner dependent on the DEN dose. Dose-dependent induction of foci was similarly noted with doses of 1-100 and 0.001-100 mg/kg body weight in the non-PH and the PH rats, respectively. The sizes of the foci were also significantly increased in a manner dependent on the DEN doses of 1-100 and 0.001-100 mg/kg body weight in the non-colchicine-treated and the colchicine-treated rats, respectively. Statistically, linear trends of 8-OHG formation due to DEN were different at 0.001-0.1 and 1-100 mg/kg body weight, but the total adducts formed within 72 h of the administration proved to be closely related to the development of foci at the termination. These results indicate that 8-OHG formation in the liver DNA may be involved in DEN initiation of hepatocarcinogenesis even at low dose levels, and that single i.p. doses of 0.001-0.1 and 1-100 mg/kg body weight might exert different effects.

Enhancement by organosulfur compounds from garlic and onions of diethylnitrosamine-induced glutathione S-transferase positive foci in the rat liver.

Ten organosulfur compounds from garlic and onions were studied for their modifying effects on diethylnitrosamine-induced neoplasia of liver in male F344 rats using the medium-term bioassay system of Ito based on the two-step model of hepatocarcinogenesis. Carcinogenic potential was scored by comparing the number and area per cm2 of induced glutathione S-transferase placental form-positive foci in the liver with those of the corresponding control group given diethylnitrosamine alone. In experiments 1 and 2, high doses of diallyl sulfide, diallyl trisulfide, allyl methyl sulfide, allyl methyl trisulfide, and dipropyl sulfide had enhancing effects on focus formation. In contrast, high doses of methyl propyl disulfide and propylene sulfide significantly decreased the number of glutathione S-transferase placental form-positive foci. In the third experiment, combined treatment with the five chemicals that had enhancing activity were fed at low doses and increased the induction of glutathione S-transferase placental form-positive foci. To investigate the mechanism of the modifying effect on hepatocarcinogenesis, ornithine decarboxylase activity was measured in diallyl sulfide-, allyl methyl sulfide-, and dipropyl sulfide-treated liver tissue without prior initiation with diethylnitrosamine, and its activity was increased compared to controls. Spermidine/spermine N1-acetyltransferase activity was not significantly changed. Formation of 8-hydroxydeoxyguanosine, a DNA adduct generated by activated oxygen species, and lipid peroxidation (2-thiobarbituric acid-reacting substance production) were also not changed. These results suggest that the promoting effect could be caused by increased cell proliferation with increased polyamine biosynthesis. In evaluating relationships between diet and cancer, it is appropriate to consider not only the possible protective role of garlic and onions but also their enhancing effects.

Inhibition by phenyl N-tert-butyl nitrone of early phase carcinogenesis in the livers of rats fed a choline-deficient, L-amino acid-defined diet.

Male Wistar rats were fed a choline-deficient, L-amino acid-defined (CDAA) diet alone or in combination with a nitrone-based free radical trapping agent, phenyl N-tert-butyl nitrone (PBN) in the drinking water at the concentrations of 0.013, 0.065, and 0.130% for 12 weeks. PBN inhibited the changes that are normally induced in the livers of rats by the CDAA diet feeding, i.e., development of putative preneoplastic lesions, proliferation of connective tissue, reduction of glutathione S-transferase activity, formation of 8-hydroxyguanine in DNA, and an increase in inducible cyclo-oxygenase (COX2) activity. PBN, however, did not prevent the increases in the COX2 mRNA or protein levels brought on by the CDAA diet These results indicate that the loss of glutathione S-transferase activity and COX2 induction may play significant roles in rat liver carcinogenesis by the CDAA diet and that PBN prevents neoplasia not only by its radical scavenging activity but also by inhibiting COX2 activity at the catalytic level.

Improved genomic/nuclear DNA extraction for 8-hydroxydeoxyguanosine analysis of small amounts of rat liver tissue.

Using two different commercially available extraction kits, genomic/nuclear DNA could be recovered from rat liver samples as small as 10 mg. Background 8-hydroxydeoxyguanosine levels in such DNA were low and stable at 0.26-0.30 +/- 0.01-0.03/10(5) guanine residues. The minimum tissue wet weight required for the accurate 8-hydroxydeoxyguanosine analysis was 25 mg. The present results indicate that routine and reliable assessment of the involvement of oxidative DNA damage in the development of various diseases, including cancer, is feasible using a variety of tissue sources.

Dimethylarsinic acid induces 8-hydroxy-2'-deoxyguanosine formation in the kidney of NCI-Black-Reiter rats.

Dirnethylarsenic peroxyl radical [(CH(3))(2)AsOO] has been postulated to be responsible for DNA damage induced by dimethylarsinic acid (DMA). In an effort to elucidate the possible mechanism of tumor-inducing potential of DMA, an experiment was designed to investigate the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a specific marker of oxidative base damage in the kidney tissues of NCI-Black Reiter (NBR) rats. Animals were divided into four groups and administered the vehicle - saline, 5, 10 and 20 mg/kg body weight respectively of DMA by gavage, once a day, 5 days a week, for a period of 4 weeks. DMA induced increase of 8-OHdG levels in the kidney of the rats treated, with the highest level at the dose of 10 mg/kg body weight. Analysis of the kidney for cell proliferation employing PCNA-positive index showed greater proliferation in the tissues of treated rats. However, DMA did not have any influence on apoptosis in this regimen. Histopathological examination of the kidney selections revealed the presence of vacuolated degeneration and dilation of the proximal tubule cells in two groups (10 and 20 mg/kg body weight). This study provides evidence to substantiate the role of DMA in inducing oxidative DNA damage in the kidney.

Hepatotoxicity and consequently increased cell proliferation are associated with flumequine hepatocarcinogenesis in mice.

It has been reported that flumequine (FLU) induces hepatic tumors in mice when given orally for 18 months. We investigated possible underlying mechanisms using a two-stage mouse hepatocarcinogenesis model. After initiation with a single intraperitoneal injection of 100 mg/kg body weight diethylnitrosamine (DEN) or saline, male CD-1 mice were given 4000 ppm FLU in the diet or 500 ppm phenobarbital (PB) in drinking water for 9, 19, 24 or 30 weeks. Toxicity, evidenced by centrilobular swollen and polar hepatocytes with fatty droplets, infiltration of inflammatory cells and increased numbers of mitosis in hepatocytes, was apparent in the livers of mice treated with FLU at all time points, but its severity declined towards the termination. FLU did not induce cytochrome P-450 enzymes such as 1A1, 2B1 and 3A2 as assessed immunohistochemically, while positive expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) was increased in hepatocytes of both DEN + FLU and FLU groups compared with the relevant controls. In animals given PB, eosinophilic swelling of hepatocytes was prominent, and the hepatocytes showed strongly positive reactions for CYP 1A1 and 3A2. Altered cell foci were induced in the livers of FLU-treated animals both with and without DEN initiation, especially the former, and their development paralleled the degree of hepatic toxicity. These results suggest that FLU hepatocarcinogenicity in mice is dependent on hepatotoxic damage and consequently increased cell proliferation. Oxidative damage to DNA may also be a crucial factor.

Selective 8-hydroxyguanine formation in pancreatic DNA due to a single intravenous administration of 4-hydroxyaminoquinoline 1-oxide in rats.

8-Hydroxyguanine (8-OHG) formation, a possible initiating event, was determined in pancreatic and liver DNA and compared with the genesis of acinar cell and hepatocyte necrosis in male Wistar rats given a single intravenous administration of 4-hydroxyaminoquinoline 1-oxide (4-HAQO). At the non-necrotic but tumorigenic dose of 7.0 mg/kg body weight, 8-OHG was selectively generated in pancreatic DNA, in the absence of acinar cell necrosis, at the 6 and 24 h time points and repaired by the 48 h time point. When rats were exposed to 4-HAQO at a necrotic dose of 14.0 mg/kg body weight, 8-OHG was also selectively formed in pancreatic DNA with the same time-dependence of generation and repair, while acinar cell necrosis became evident at the 24 h time point and progressed thereafter. Whereas no hepatocyte necrosis was detected in any rats, 8-OHG values for liver DNA merely expressed slight increases only at the 24 and 48 h time points in rats given 14.0 mg/kg body weight of 4-HAQO. The present data suggest that formation of oxidative DNA damage, assayed by 8-OHG, in pancreatic DNA is independent from toxicity and may be involved, along with quinoline adducts, in mutational events underlying 4-HAQO-induced rat acinar cell carcinogenesis.

Infrequent Ki-ras and an absence of p53 mutations in hepatocellular carcinomas induced by a choline deficient L-amino acid defined diet in rats.

Mutations of Ki-ras and p53 genes in hepatocellular carcinomas (HCCs) induced by the choline deficient L-amino acid defined (CDAA) diet in rats were investigated by polymerase chain reaction (PCR), single strand conformation polymorphism (SSCP) analysis followed by direct sequencing. Male Fischer 344 rats, 6 weeks old, were continuously given a CDAA diet for 70 weeks and then sacrificed. Macroscopically detectable nodules which were histologically confirmed to be well-differentiated HCCs were dissected free from the surrounding tissue and subjected to gene mutation analysis along with samples of non-tumor areas. Conformational change in the Ki-ras gene was detected in 1 out of 7 HCCs, involving a GGC to GTC transversion at codon 13. No p53 mutations were detected in 7 HCCs and also neither Ki-ras nor p53 mutations were found in non-tumor areas. The results suggest that neither Ki-ras nor p53 genes play an important role in hepatocarcinogenesis caused by long term expose to a CDAA diet in rats.

Increased telomerase activity and absence of p53 mutation in oligoastrocytomas induced by N-ethyl-N-nitrosourea in rats.

The question of whether the changes in telomerase activity and/or the alteration of the p53 gene are involved in the development of oligo-astrocytomas induced by N-ethyl-N-nitrosourea (ENU) in rats was addressed. Telomerase activity levels of oligo-astrocytomas, including early neoplastic lesions, were significantly increased as compared to the normal controls, correlating with the degree of malignancy. In contrast, no mutations of p53 exons 5-7 were found in early neoplastic lesions or oligo-astrocytomas. These results indicate that the activation of telomerase occurs during astrocytoma carcinogenesis and contributes to the development of brain tumors, but the alterations of p53, at least on exons 5-7, may not be involved in this process.

Increased telomerase activity in intrahepatic cholangiocellular carcinomas induced by N-nitrosobis(2-oxopropyl)amine in hamsters.

Telomerase activities in intrahepatic cholangiocarcinomas induced by N-nitrosobis(2-oxopropyl)amine (BOP) in female hamsters were determined using a telomeric repeat amplification protocol (TRAP) assay followed by densitometric quantification. Each determination was repeated to confirm the results and telomerase activity was also detected by gel electrophoresis. An increase was evident in all of 10 cholangiocarcinomas examined, with levels ranging from 2.48 to 4.40 times the normal liver value by densitometric quantification. This finding of a consistent increase suggests that telomerase activation is involved in the development of intrahepatic cholangiocarcinomas and immortalization of cancer cells.

Protein thiol depletion and the killing of cultured hepatocytes by hydrogen peroxide.

The H2O2 generated by menadione kills cultured hepatocytes by a mechanism that depends in large part on a cellular source of ferric iron. Chelation of this iron by deferoxamine reduced by two-thirds the number of dead cells without any effect on the loss of 30% of total protein thiols, the formation of protein mixed disulfides, or the accumulation of oxidized glutathione (GSSG). The loss of protein thiols was accounted for by the formation of glutathione mixed disulfides from GSSG and the arylation of protein nucleophiles by menadione. Nevertheless, such a loss occurred despite the chelation of cellular iron and a substantial reduction in the extent of cell killing. With the H2O2 generated by glucose oxidase, lipid peroxidation and a loss of 40% of the total protein thiols accompanied the cell killing within 1 hr. Deferoxamine, superoxide dismutase and the antioxidant N,N'-diphenyl phenylenediamine (DPPD) prevented the cell killing and two-thirds of the loss of protein thiols. Peroxidation of liver microsomes in vitro with ADP:Fe3+ similarly depleted protein thiols, an effect that was prevented by DPPD. The supernatant fraction from the peroxidation assay depleted the protein thiols of cultured hepatocytes without an effect on viability. Thus, lipid peroxidation accounted for the major part of the loss of protein thiols with glucose oxidase. The 10-15% decrement in protein thiols after 1 hr that occurred in the absence of cell killing reflected the formation of glutathione mixed disulfides. Finally, in the presence of DPPD, glucose oxidase killed 75% of the cells between 1 and 3 hr without any further change in protein thiols. Thus, under the conditions studied, the depletion of protein thiols by the three mechanisms, namely lipid peroxidation, formation of glutathione mixed disulfides, and arylation, does not necessarily have a causal relationship to the killing of cultured hepatocytes.

Studies of carcinogenicity of sodium chlorite in B6C3F1 mice.

The carcinogenic activities of sodium chlorite in B6C3F1 mice were examined. Sodium chlorite was given at concentrations of 0 (control), 0.025% (low dose), or 0.05% (high dose) in the drinking water of 150 female and 150 male mice for 80 weeks, after which time the animals were returned to distilled water without sodium chlorite. All mice were sacrificed 85 weeks from the beginning of the experiment. The incidence of tumor-bearing animals was 32% (control), 34% (low dose), and 26% (high dose) in female mice, and 46% (control), 57% (low dose), and 53% (high dose) in male mice. The types and incidence of neoplasms that occurred frequently in each group of both sexes were similar to those observed spontaneously in B6C3F1 mice. The incidence of lymphomas/leukemias in the high dose group of females (2%), however, was lower than that in the control group (15%). Furthermore, the incidence of pulmonary adenomas in the high dose group of males (12%) was higher than that in the control group (0%), but neither dose-related increases in the adenoma incidences nor increased incidences of the adenocarcinomas were observed. These results indicated no clear evidence of a carcinogenic potential of sodium chlorite in B6C3F1 mice.

Protection against lipid peroxidation induced during preservation of lungs for transplantation.

The questions of whether oxygen-derived free radicals are induced during preservation of lungs and, if so, how such radicals might relate to reperfusion injury were investigated by means of an isolated canine lung model. Lungs were obtained from 16 mongrel dogs and divided into groups 1 (n = 6), 2 (n = 5), and 3 (n = 5). The lungs of groups 1, 2, and 3 were flushed through the pulmonary artery with Euro-Collins solution alone, the solution with superoxide dismutase (120,000 U/L), and the solution with allopurinol (1 mmol/L), respectively, at 4 degrees C and then stored for 4 hours in the respective solutions at 4 degrees C with clamped bronchi. They were then reperfused for 2 hours by means of an isolated lung model. Lung lipid peroxidation was sequentially determined. The lung functional status was assessed by systolic pulmonary arterial pressure and end-inspiratory airway pressure. The lung edema was assessed by lung wet/dry weight ratio. Lipid peroxidation was induced after 1 hour of preservation and the first 30 minutes of the reperfusion in group 1 and only 2 hours of the reperfusion in group 2, whereas no induction was observed in group 3. Values for systolic pulmonary arterial pressure and end-inspiratory pressure in group 1 were significantly higher than those in group 3 (p < 0.05). The lung wet/dry weight ratio in group 1 was significantly higher than that in groups 2 and 3 (p < 0.05). The present results indicate that the administration of free radical scavengers in the preservation may effectively improve conditions for lung transplantation.

Existence of a threshold for induction of aberrant crypt foci in the rat colon with low doses of 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine.

Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the nonthreshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that a food derived, genotoxic hepatocarcinogen, 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine (PhIP), does not induce aberrant crypt foci (ACF) as preneoplastic lesions at low dose (below 50 ppm) or 8-hydroxy-2'-deoxyguanosine (below 400 ppm) in the rat colon. Moreover PhIP-DNA adducts were not formed at the lowest dose (below 0.01 ppm). Thus, the dose required to initiate ACF is approximately 5000 times higher than that needed for adduct formation. The results imply a no-observed effect level (existence of a threshold) for colon carcinogenesis by a genotoxic carcinogen.

Spontaneous passage of a colon cast in the absence of abdominal aneurysm.

The spontaneous passage of colon cast from a 76-year-old Japanese female patient is reported. Macroscopically, the colon case was shaped like the airbladder of a fish. Histopathologically, the cast consisted of degenerated colonal mucosa, including glands. No inflammatory reaction was apparent. The patient lacked any evidence of abdominal aneurysm. Since there have been only five reported cases of colon cast in the literature, and since in all of those association with abdominal aneurysms was always described, the present study represents the first report demonstrating the formation of a colon cast in the absence of associated abdominal aneurysm. However, the patient was found to exhibit several risk factors for ischemic colitis, such as arteriosclerosis on the wall of the abdominal aorta, chronic constipation, and colonic stenosis. Her colonal mucosal surface, indeed, suggested ischemic colitis. This case report, therefore, indicates that ischemic colitis, due to various causes, may be responsible for the formation of colon casts, and that the presence of an abdominal aneurysm is not necessarily a prerequisite for colon cast formation. This report may contribute to a better understanding of the pathogenesis of colon casts.