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Biomedical subjects

K Imaida

Publications and source records attributed to K Imaida.

At least 145 records · Page 8Linked to original sources
PubMed1988

Effects of urinary crystals induced by acetazolamide, uracil, and diethylene glycol on urinary bladder carcinogenesis in N-butyl-N-(4-hydroxybutyl)nitrosamine-initiated rats.

In order to examine the promoting effect of urinary crystals on urinary bladder carcinogenesis, acetazolamide, uracil, and diethylene glycol, all of which have been reported to cause urinary crystals or calculi, were administered to male F344 rats for 32 weeks after pretreatment with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 4 weeks. A marked increase in urinary crystals was observed in acetazolamide-treated rats and a slight increase in crystals was observed in uracil- and diethylene glycol-treated rats. Histological examination of the urinary bladder revealed that the BBN-acetazolamide treatment resulted in a higher incidence of carcinoma than BBN-control. Uracil and diethylene glycol did not cause any significant difference compared to the control. Promoting effects by urinary crystals were not clearly shown in the present experiment and, therefore, urinary crystals appear to play a very limited role, if any, in urinary bladder carcinogenesis.

Acetazolamide↗
PubMed1988

Primary choriocarcinoma of the urinary bladder.

A case of choriocarcinoma of the urinary bladder is presented. A 57-year-old man underwent a cystectomy for transitional cell carcinoma, grade II. Choriocarcinoma was found, in addition to the transitional cell carcinoma, in the removed urinary bladder. After the operation, metastases appeared in both lungs, evolving rapidly despite chemotherapy. The patient died five months after admission. Immunohistochemically, staining for human placental lactogen was strongly positive, and both alpha and beta subunits of human chorionic gonadotropin were weakly positive in the primary site of the removed urinary bladder and in the metastatic foci.

Carcinoma, Transitional Cell↗
PubMed1988

A new medium-term bioassay system for detection of environmental carcinogens using diethylnitrosamine-initiated rat liver followed by D-galactosamine treatment and partial hepatectomy.

The effects of D-galactosamine on induction of preneoplastic glutathione S-transferase placental form positive liver foci were investigated in F344 rats pretreated with diethylnitrosamine (DEN) in an attempt to improve the predictive value of the medium-term bioassay system developed in our laboratory. Two weeks after the initial single ip dose (200 mg/kg) of DEN, administration of test compounds was commenced simultaneously with an ip injection of D-galactosamine at a dose of 300 mg/kg body wt. All rats were then subjected to two-thirds partial hepatectomy (PH) at week 5 and sacrificed for assessment of lesion yield at week 8. Measurement and comparison of the numbers and areas of glutathione S-transferase placental form positive (GST-P+) foci per cm2 revealed a positive response to more carcinogens, including non-hepatocarcinogens, than did the same bioassay system without injection of D-galactosamine. Thus the results suggest that inclusion of this extra proliferative stimulus may improve the medium-term detection of carcinogens and modifiers.

Animals↗
PubMed1988

Wide-spectrum initiation models: possible applications to medium-term multiple organ bioassays for carcinogenesis modifiers.

Two wide-spectrum initiation models were investigated in F344 male rats. Model I: After sequential treatment with diethylnitrosamine (DEN), N-methylnitrosourea (MNU) and dihydroxy-di-N-propylnitrosamine (DHPN), animals were given phenobarbital (PB) or N,N-dibutylnitrosamine (DBN) as a test compound for 14 weeks and sacrificed at week 18. Model II: Animals were treated with DHPN, followed by N-ethyl-N-hydroxyethylnitrosamine (EHEN), and then 3,2'-dimethyl-4-aminobiphenyl (DMAB) as initiators and were subsequently given 3-methylcholanthrene (MCA) or PB as a test compound for 11 weeks. Animals were sacrificed 16 weeks after the commencement. In both models, assessment of lesion yield revealed significant enhancement of carcinogenesis by the test compounds in their respective target organs. Since, in many cases, treatment with PB, DBN and MCA subsequent to the combined initiation procedures brought about a marked increase in lesion development, far greater than a simple sum of the yields given by initiators and test compounds alone, the presently described approach appears promising for development of medium-term bioassay systems for detection of environmental carcinogens.

Animals↗
PubMed1988

Strain differences in N-butyl-N-(4-hydroxybutyl)nitrosamine bladder carcinogenesis in rats.

Differences in susceptibility of the urinary bladder epithelium to N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) in various strains were examined. In experiment 1, 5 strains of male rats were given 0.025% BBN in the drinking water for 8 weeks followed by drinking water without BBN for 32 weeks. Analbuminemic rats (NAR) and ACI rats had high incidences of urinary bladder lesions (papillary or nodular hyperplasia, papilloma and carcinoma), F344 and Wistar rats had low incidences, and Sprague-Dawley (SD) rats showed an intermediate incidence. Carcinoma area was largest in NAR rats followed in decreasing order by SD, ACI and F344 rats. The extent of tumor invasion was higher in NAR and ACI rats than in SD rats. In experiment 2, the 5 strains of male rats were administered 0.025% BBN in the drinking water. Some rats from each group were killed after each of weeks 4 and 8. The urinary bladder of ACI and NAR rats given BBN had the most marked lesions observed by scanning electron microscopy, with less marked changes in SD rats. F344 and Wistar rats showed the weakest response. Cytochrome P-450 content of the liver in ACI rats treated with BBN for 4 weeks was significantly higher than those of controls. Cytochrome P-450 and cytochrome b5 contents of the control and BBN-treated rats were significantly higher in ACI and SD rats than in Wistar, F344 or NAR rats. These results indicate that there are strain differences in the urinary bladder response to BBN.

Animals↗
PubMed1988

Effects of phenobarbital and carbazole on carcinogenesis of the lung, thyroid, kidney, and bladder of rats pretreated with N-bis(2-hydroxypropyl)nitrosamine.

Studies were made on potential modifying effects of phenobarbital (PB) and carbazole on tumor development induced by N-bis(2-hydroxypropyl)nitrosamine (DHPN), a wide-spectrum carcinogen in rats. Effects on the lung, thyroid, kidney, bladder and liver were investigated. Male F344 rats were given 0.2% DHPN in their drinking water for 1 week and then 0.05% PB or 0.6% carbazole in their diet for 50 weeks. Control animals were treated with either DHPN or PB or carbazole only. Neither PB nor carbazole affected the incidence or histology of lung tumors. However, PB promoted the development of thyroid tumors and preneoplastic lesions of the liver, while carbazole promoted the induction of renal pelvic tumors.

Adenoma↗
PubMed1988

Condyloma acuminatum of the bladder in two autopsy cases.

Condyloma acuminatum is a very rare lesion occurring in the bladder. We report two cases of condyloma acuminatum of the bladder found at autopsy, one in a 96-year-old woman and the other in an 80-year-old man. Both had papillary or polypoid tumorous lesions in the trigone and neck of the bladder. The lesions were composed of nodular or papillary growths of squamous epithelium. The epithelium exhibited koilocytosis and the nuclei showed immunohistochemical staining for human papillomavirus antigen.

Aged↗
PubMed1987

Strong promoting activity of reversible uracil-induced urolithiasis on urinary bladder carcinogenesis in rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine.

The tumor-promoting effect of uracil-induced calculi on rat urinary bladder carcinogenesis was investigated in male F344 rats pretreated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Since uracil-induced calculi and papillomatosis of the bladder are reversible, uracil was given for a limited period after the treatment with BBN. Animals were given 0.05% BBN in their drinking water for 4 wk and then treated with uracil as 3% of the diet for 8 or 16 wk. After the uracil treatment, rats were given basal diet without uracil until Wk 28 of the experiment. Animals were killed from each group at the end of either Wk 12, 20, or 28. The incidence of carcinoma of the bladder was 40% after only 8 wk of uracil treatment following BBN initiation and increased to 100% when uracil treatment was extended to 16 wk. After discontinuation of uracil treatment, the papillomatosis disappeared, but the incidence of carcinoma steadily increased with increasing time. In the control group given BBN alone, only 1 of 16 rats had carcinoma at Wk 28. The present findings clearly demonstrate that uracil-induced urolithiasis had a strong promoting activity on BBN bladder carcinogenesis.

Animals↗
PubMed1987

Compared promoting potential of D-galactosamine, carbon tetrachloride and partial hepatectomy in rapid induction of preneoplastic liver lesions in the rat.

Effectiveness of two different chemically induced stimuli for hepatocellular proliferation was compared with regard to that of commonly used partial hepatectomy (PH), for the purpose of developing short-term protocol for the assay of promoting agents of hepatocarcinogenesis. Enhancing effect of D-galactosamine (DGA) and carbon tetrachloride (CCl4) given during the promotion procedure by 2-acetylaminofluorene (2-AAF) was compared along with PH in rats initiated by diethylnitrosamine (DEN), using preneoplastic glutathione S-transferase positive (GST-P+) hepatocyte foci as an end-point marker lesion. The number of GST-P+ foci per cm2 was largest in the group given CCl4 followed by DGA, no treatment (2-AAF alone) and PH. In contrast, the area (mm2) per cm2 and mean diameter of the focus were largest in the PH group then DGA followed by CCl4 and no treatment. The results indicate that the number of GST-P+ foci were not clearly affected by 3 different treatments whereas area and size of foci which represented the result of promoting effect were clearly influenced by those treatments, indicating they caused differential proliferation of initiated cells. In this respect, even though PH is the most potent procedure, DGA is also efficient and preferred to CCl4 for the non-surgical enhancing method.

Animals↗
PubMed1987

Promotion by L-ascorbic acid of urinary bladder carcinogenesis in rats under conditions of increased urinary K ion concentration and pH.

Dietary administration of 5% L-ascorbic acid plus 3% K2CO3 to male F344 rats clearly enhanced the development of preneoplastic and neoplastic lesions of the urinary bladder initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine. Promotion of carcinogenesis by L-ascorbic acid and K2CO3 was associated with changes in urinary parameters: elevation of pH, increased K+ concentration, and increase in total ascorbic acid.

Animals↗
PubMed1987

Production of urothelial tumors in the heterotopic bladder of rats by instillation of N-glucuronosyl or N-acetyl derivatives of N-hydroxy-2-aminofluorene.

Male F344 rats which had been implanted with a heterotopic bladder were randomly divided into four groups and their heterotopic bladders were instilled once a week for 30 weeks with 0.5 ml phosphate-buffered saline-dimethyl sulfoxide solution (4:1), or this solution containing 2 mumol N-methyl-N-nitrosourea, 1 mumol N-hydroxy-2-acetylaminofluorene (N-OH-AAF), or 1 mumol N-hydroxy-N-glucuronosyl-2-aminofluorene (N-OH-N-Gl-AF). These bladders were then instilled once a week for an additional 23 weeks with phosphate buffered saline solution without the addition of dimethyl sulfoxide. The animals were killed at the end of 53 weeks. Transitional cell carcinomas were observed in five of 37, 36 of 37, 15 of 35, and 36 of 38 rats of the control, N-methyl-N-nitrosourea, N-OH-AAF, and N-OH-N-Gl-AF groups, respectively. No histological alteration was observed in their natural bladders and no tumor was observed in the liver. As judged by kinetic measurements of the radioactive compounds, N-OH-AAF was removed much faster than N-OH-N-Gl-AF from the fluid of heterotopic bladder. The pH of the fluid in the bladder was between 7.1 and 7.4. The present study demonstrates the carcinogenicity of N-OH-N-Gl-AF and N-OH-AAF for rat bladder.

2-Acetylaminofluorene↗
PubMed1987

Proliferative response of rat accessory sex organs to dietary sex hormones after castration or initial dietary administration of estrogen.

The hormone dependent proliferative response of five accessory sex organs was examined subsequent to castration-induced or estrogen-induced atrophy using male six-week-old F344 rats. Three weeks after castration, rats were treated with dietary methyltestosterone (300 ppm), ethinyl estradiol (0.75 ppm) or methyltestosterone plus ethinyl estradiol for up to 17 days. Cell proliferation was assessed by 3H-thymidine incorporation as determined from labelling indices using autoradiography. The maximum labelling indices which appeared on days 2 or 3 of administration of methyltestosterone were 24.3, 8.4, 9.6, 21.6 and 13.7% for the ventral, lateral and dorsal prostate, seminal vesicle and coagulating glands, respectively. Combined methyltestosterone and ethinyl estradiol induced mild proliferative responses whereas ethinyl estradiol did not. In a further group of non-castrated rats which were pretreated with dietary ethinyl estradiol for three weeks and then given methyltestosterone, the maximum labelling indices were about 70 to 80% of that in castrated rats.

Animals↗
PubMed1987

Inhibition of neoplastic development in rat liver, kidney, oesophagus and forestomach by 4,4'-diaminodiphenylmethane administration.

The modifying effects of 4,4'-diaminodiphenylmethane (DDPM) (0.1% in diet) administration on liver carcinogenesis induced by 2-acetylaminofluorene (2-AAF) (0.02% in diet), 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) ( 0.06% in diet), diethylnitrosamine (DEN) (0.001% in drinking water) and N-ethyl-N-hydroxyethylnitrosamine (EHEN) (0.1% in drinking water), EHEN-induced oesophagus and kidney carcinogenesis and forestomach carcinogenesis induced by butylated hydroxyanisole (1.0% in diet) were examined in F344 male rats. Mean survival time tended to be longer in DDPM-supplemented groups, the difference being significant in DEN + DDPM and EHEN + DDPM groups. Intake of carcinogens was slightly but not significantly reduced by DDPM. The incidences of hyperplastic nodules and hepatocellular carcinomas were significantly decreased in 2-AAF or 3'-Me-DAB + DDPM groups. Pulmonary metastases were also less common in 3'-Me-DAB or EHEN + DDPM groups. Development of papillomas in the oesophagus but not in tumours in the forestomach was also inhibited by DDPM. Inhibition in the different organs was not significantly related to decrease in body weight or carcinogen intake, indicating a mechanism independent of non-specific toxic effects or reduction in food consumption. Some other factors possibly related to its ability to cause bile duct proliferation and/or altered activity of enzymes relevant to drug metabolism may be involved.

2-Acetylaminofluorene↗
PubMed1987

Induction of forestomach lesions in rats by oral administrations of naturally occurring antioxidants for 4 weeks.

The effects of naturally occurring antioxidants on rat forestomach epithelium were compared with those of synthetic antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), of which the former is a known forestomach carcinogen. Groups of five F344 male rats were given diet containing BHA, BHT, gallic acid, syringic acid, sesamol, caffeic acid, chlorogenic acid, ferulic acid, eugenol or esculin for 4 weeks at a level of 0.7% for BHT or 2% for other compounds. Histological examination of the forestomach showed that BHA induced hyperplasia mainly in the prefundic region near the esophageal orifice, caffeic acid induced pronounced hyperplasia throughout the forestomach epithelium, and sesamol induced large ulcers and hyperplasia in the central region. Thus, these naturally occurring antioxidants showed different toxicities and abilities to induce hyperplasia in the rat forestomach.

Animals↗
PubMed1986

Sequential changes of the forestomach of F344 rats, Syrian golden hamsters, and B6C3F1 mice treated with butylated hydroxyanisole.

Butylated hydroxyanisole (BHA) was given to F344 rats, Syrian golden hamsters and B6C3F1 mice at 2 doses for up to 104 weeks. The two doses were 2.0% and 1.0% for rats and hamsters, and 1.0% and 0.5% for mice. Animals were sacrificed sequentially at 8-week intervals from week 8 to week 104, and the carcinogenic effects of BHA on the forestomach were examined histopathologically. Papillomas and carcinomas were found in rats, hamsters and mice. In rats, papillomas first appeared in week 8 in the group given the higher level of BHA and in week 56 in that given the lower level. The first carcinoma was observed in week 48 in rats given the high level, while no carcinoma was observed in rats given the lower level. In hamsters, papillomas appeared in week 8 in both BHA-treated groups, and in both groups, the incidence of papillomas was much higher than in BHA-treated rats. Squamous cell carcinomas were observed in 4 hamsters (10.0%) among those that survived more than 64 weeks on treatment with the higher level of BHA and in 4 (7.3%) among those treated with the lower level. In mice, papillomas were induced by BHA in both BHA-treated groups after more than 88 weeks. Although the incidence was not statistically significant, carcinoma was also seen in mice, suggesting that BHA may also be carcinogenic to mouse forestomach.

Animals↗
PubMed1986

Effect of sodium phenobarbital and sodium saccharin in AIN-76A diet on carcinogenesis initiated with N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide and N,N-dibutylnitrosamine in male F344 rats.

Promoting activities of sodium phenobarbital (PB) and sodium saccharin (SS), incorporated in a semisynthetic diet (AIN-76A), on 2-stage carcinogenesis initiated with N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) or N,N-dibutylnitrosamine (DBN) in male F344 rats were investigated. For the first 4 weeks of the experiment, weanling male Fischer rats were fed Wayne diet containing 0.2% FANFT or drinking water containing 0.005% DBN. The control rats were given the basal diet and normal drinking water. Beginning at the fifth week, the rats were given the AIN-76A diet or this diet containing 0.05 or 0.15% PB or 5% SS. The experiment was terminated at the end of 100 weeks. PB significantly increased the incidence of transitional cell carcinoma of the bladder of the rats that had been treated with FANFT (P = 0.027). PB also increased the incidence of bladder carcinoma of the rats that had been treated with DBN, but the increase was not significant (P = 0.081). SS in the AIN-76A diet increased the incidence of bladder carcinoma in the rats which had been treated with FANFT or DBN, but the increase was not significant (P = 0.059 and 0.327, respectively). Both high and low doses of PB, but not SS, significantly increased the incidence of hepatocellular carcinoma in the rats that had been treated with DBN. None of the control rats that had been fed the basal diet or the basal diet containing low or high PB or 5% SS developed either bladder or liver carcinoma. These results demonstrate that PB promotes urinary bladder carcinogenesis of rats initiated with FANFT but not with DBN. In contrast to incorporation in commercial rat chows, SS incorporated in the AIN-76A diet is very weak in promoting bladder carcinogenesis. On the other hand, PB, but not SS, promotes hepatocarcinogenesis initiated with DBN. Neither PB nor SS promoted DBN-induced carcinogenesis of esophagus or forestomach.

Animals↗