Search PubMed⌕ Search

Biomedical subjects

M Ohshima

Publications and source records attributed to M Ohshima.

At least 145 records · Page 8Linked to original sources
PubMed1984

Effects of butylated hydroxyanisole, butylated hydroxytoluene, and NaCl on gastric carcinogenesis initiated with N-methyl-N'-nitro-N-nitrosoguanidine in F344 rats.

Promoting activities of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and NaCl and of combinations of these antioxidants with NaCl on gastric carcinogenesis initiated by N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) (CAS: 70-25-7; 1-methyl-3-nitro-1-nitrosoguanidine] were investigated in male inbred F344 rats. Animals, 6-week old, were given an intragastric administration of MNNG at 150 mg/kg body weight by gastric tube and 1 week later were placed on a diet containing BHA (0.5%), BHT (1.0%), NaCl (5.0%), BHA (0.5%) plus NaCl (5%), or BHT (1.0%) plus NaCl (5.0%) for 51 weeks. Control rats received no further treatment after MNNG administration. A single intragastric application of MNNG to rats induced multiple epithelial tumors of the forestomach and a few epithelial tumors of the glandular stomach after 52 weeks. Squamous cell carcinomas of the forestomach were seen in 2 of 18 effective rats (11.1%) in the control groups, and the incidences in the groups receiving the subsequent treatment were 45.0% with BHA, 15.8% with BHT, 30% with NaCl, 70% with BHA plus NaCl, and 52.9% with BHT plus NaCl. Differences in the incidences of squamous cell carcinoma between the controls and groups given BHA, BHA plus NaCl, and BHT plus NaCl were statistically significant. NaCl given alone after MNNG administration also significantly increased the incidence of papillomas in the forestomach. Incidences of glandular stomach tumors, adenomas and carcinomas were not affected by any of the subsequent treatments. No tumors of the stomach developed in the groups given BHA, BHT, and NaCl without MNNG pretreatment. Thus the present experiment revealed that BHA and NaCl but not BHT exert promoting activity on MNNG-induced forestomach carcinogenesis in rats and that, when BHA and BHT were given with NaCl, promotion was more marked, suggesting a synergistic effect on tumor promotion.

Animals↗
PubMed1984

Promotion of N-methyl-N-nitrosourea-induced thyroid tumors by iodine deficiency in F344/NCr rats.

Six-week-old male F344 rats were each given an injection once iv of N-methyl-N-nitrosourea [(MNU) CAS: 684-93-5] at a dose of 41.2 mg/kg body weight. Two weeks later, groups of rats were placed on iodine-deficient (ID) or iodine-adequate (IA) diets and then sacrificed at 20 and 33 weeks. Other groups received ID or IA diets without MNU. For localizing thyroid-stimulating hormone (TSH) and prolactin, sections of pituitary glands were stained by the avidin-biotin-peroxidase complex technique with the use of anti-rat TSH or prolactin antibody. At 20 weeks, rats receiving MNU and ID diets had a 100% incidence of diffuse follicular goiter and multiple follicular adenomas of the thyroid. Focal proliferative thyroid follicular lesions including focal hyperplasias and adenomas per square centimeter of thyroid gland were significantly increased in rats given MNU and ID diets in comparison with rats given MNU and IA diets. At 33 weeks, all MNU rats on ID diets had a significantly increased incidence of thyroid carcinoma of the follicular or papillary types and diffuse pituitary thyrotroph hyperplasia, hypertrophy, and vacuolar degeneration. Rats fed ID diets without MNU had diffuse follicular goiter but no tumors at any time period. MNU given alone in rats fed IA diets induced a 10% incidence of single thyroid adenomas at 20 weeks and 70% at 33 weeks and a 10% incidence of thyroid carcinoma at 33 weeks. Tumors induced in other organs by MNU were not affected by the ID diets. Thus this experiment provided evidence that ID diets are potent promoters of thyroid tumors in this system, but the ID diet itself without carcinogen was not carcinogenic under the conditions of the study.

Animals↗
PubMed1983

Structural organization of the tissue-specific middle repetitive sequence of the mouse genome.

The structural genes closely linked to the particular middle repetitive sequence (MRS) expressed in liver nuclei were cloned from the mouse genomic library. From one-fourth of 3,200 MRS-containing clones, 21 clones were obtained as mRNA coding sequence-linked MRS clones. From examination of the structural organization and specificity of expression of the MRS and the mRNA coding sequence, it was concluded that expressions of the MRS and the structural genes closely linked to the MRS are independently regulated.

Animals↗
PubMed1983

Basic lead acetate: promoting effect on the development of renal tubular cell tumors in rats treated with N-ethyl-N-hydroxyethylnitrosamine.

The development of renal tubular cell tumors by the end of experimental week 32 was studied in inbred Wistar male rats fed a diet containing 1,000 or 500 ppm N-ethyl-N-hydroxyethylnitrosamine (EHEN) for 2 weeks and then given 1,00 ppm basic lead acetate (LA) for 20 weeks. A low dose of LA enhanced the development of renal tubular cell tumors in rats treated with EHEN and increased the number and size of the tumors. The incidence of renal tubular cell tumors at the end of week 32 was 50% in rats treated with 1,000 ppm EHEN for 2 weeks and 100% in rats treated with 1,000 ppm EHEN for 2 weeks and then given 1,000 ppm LA for 20 weeks. The incidences of renal tumors of more than 3 mm in diameter were 70% in rats treated with 1,000 ppm EHEN plus LA and 0% in rats treated with EHEN or LA alone. The low dose of LA showed the enhancing effect of the development of renal tubular cell tumors in rats treated with a subthreshold dose of 500 ppm EHEN.

Animals↗
PubMed1982

Promoting effects of phenobarbital and barbital on development of thyroid tumors in rats treated with N-bis(2-hydroxypropyl)nitrosamine.

Phenobarbital (PB) and barbital (BB) promoted the development of thyroid tumors in rats treated with a sub-effective dose of N-bis(2-hydroxypropyl)nitrosamine (DHPN) for thyroid tumorigenesis. Rats were given s.c. injections of 70 mg DHPN/100 g body weight once a week for 4 or 6 weeks with or without diet containing 500 p.p.m. PB or BB for the next 12 weeks. The incidences of thyroid tumors at the end of week 20 of the experiment were 66% in rats given DHPN for 4 weeks and then PB, 23% in rats given DHPN for 4 weeks and then BB, 100% in rats given DHPN for 6 weeks and then PB, 45% in rats given DHPN for 6 weeks and then BB, and 23% in rats given DHPN for 6 weeks. Rats given only DHPN for 4 weeks or only PB or BB had no thyroid tumors after 20 weeks.

Animals↗
PubMed1982

Promoting effects of 3-amino-1,2,4-triazole on the development of thyroid tumors in rats treated with N-bis(2-hydroxypropyl)nitrosamine.

3-Amino-1,2,4-triazole (AT) promoted the development of thyroid tumors in rats treated with a subeffective dose of N-bis(2-hydroxypropyl)nitrosamine (DHPN) for thyroid tumorigenesis. The incidences of thyroid tumors at the end of the 20-week experiment were 91% in rats injected s.c. once a week for four weeks with 70 mg DHPN per 100 g body weight and then given diet containing 2000 p.p.m. AT for 12 weeks, 100% in rats injected s.c. once a week for eight weeks with 70 mg DHPN per 100 g body weight and then given diet containing 2000 p.p.m. AT for 12 weeks, and 58% in rats injected s.c. once a week for 8 weeks with 70 mg DHPN per 100 g body weight. Rats only injected s.c. once a week for four weeks with DHPN or only given diet containing AT for 12 weeks had no thyroid tumors at the end of the experiment.

Amitrole↗
PubMed1982

beta-Cyclodextrin: promoting effect on the development of renal tubular cell tumors in rats treated with N-ethyl-N-hydroxyethylnitrosamine.

Injection (sc) of beta-cyclodextrin (beta-C) increased the number and size of renal tubular cell tumors in inbred Wistar (W) rats treated with 1,000 ppm of N-ethyl-N-hydroxyethylnitrosamine (EHEN). The incidence of renal tumors at the end of the 32-week experiment was 50% in rats treated with 1,000 ppm EHEN for 2 weeks and 100% in rats treated with 1,000 ppm EHEN for 2 weeks and then given daily sc injections of beta-C for 1 week. The incidence of renal tumors more than 3 mm in diameter was 70% in rats treated with 1,000 ppm EHEN before beta-C but 0% in rats treated with EHEN alone. In addition, beta-C promoted the development of renal tumors in rats treated with 500 ppm EHEN, which is a subthreshold dose for renal tubular cell tumorigenesis. These results show that beta-C promotes EHEN-induced renal tubular cell tumorigenesis.

Animals↗
PubMed1982

Carcinogenic effect of carbazole in the liver of (C57BL/6N x C3H/HeN)F1 mice.

The carcinogenic effect of carbazole (9H-carbazole) in (C57BL/6N X C3H/HeN)F1 (B6C3F1) mice was examined. Groups of 50 mice of both sexes were given a basal diet containing 0.6, 0.3, or 0.15% carbazole for 96 weeks and were then placed on an unsupplemented basal diet until they were killed at week 104. Mice surviving longer than 52 weeks were included in effective numbers. Significant increases in the induction of neoplastic lesions were found in the livers and forestomachs of mice given carbazole as compared to the control groups. The lesions in the livers were classified into two types, neoplastic nodules or hepatocellular carcinomas. The incidences of both types of lesions were almost 100% in mice treated with carbazole, and both types of lesions were significantly increased in all mice except the males given 0.6% carbazole in their diet. The incidences of hepatocellular carcinomas were in general higher than those of neoplastic nodules. Though not statistically significant, increased incidences of pulmonary metastases were found in the groups given carbazole. Significantly increased incidences of neoplastic lesions and papillomas in the forestomach in all groups of female and male mice were also noted in the mice fed 0.6% carbazole. Squamous cell carcinoma induction was significantly different in male mice given 0.6% carbazole as compared to controls. These results indicate that carbazole is carcinogenic to the liver and forestomach in B6C3F1 mice and suggest that carbazole may be an environmental carcinogen relevant to cancer risk in humans.

Animals↗
PubMed1981

AFP in yolk sac tumor and solid teratoma of the ovary: significance of postoperative serum AFP.

Serial serum alpha-fetoprotein (AFP) was examined postoperatively in five patients with yolk sac tumor and in three with solid teratoma of the ovary. Serial estimation of AFP was also done in sera from postpartum patients to compare the decreasing ratio between the two groups. Serum AFP in these postpartum women decreased according to the exponential function curve as AFP = be-mx (x = days after delivery) with a mean m value of 0.1652 and a mean correlation coefficient of -0.9911. Half-time of serum AFP in postpartum subjects was 4.33 days. Exponential decrease of serum AFP was also found in postoperative patients with yolk sac tumor and solid teratoma of the ovary. However, in those in whom there was an incomplete removal of the tumors, the values of either m or coefficient of correlation were significantly lower as compared to those in patients with complete extirpation of lesions or those in postpartum subjects. Elevation of serum AFP was noted postoperatively in two patients with recurrences; however, significant decreases in AFP following chemotherapy were apparent in one patient with immature solid teratoma. These findings suggest that the decreasing ratio of postoperative serum AFP is an effective indicator to determine whether or not the lesions were completely extirpated, although a normal value may not always imply the absence of microscopic metastasis of tumor cells. Serial estimation of serum AFP was of value in assessing the presence of recurrences and evaluating the efficacy of chemotherapy.

Adolescent↗
PubMed1981

Confirmation of the development of multiple renal cell tumors in endstage/long-term hemodialysis kidney revealed typical acquired cystic transformation.

Histopathological study of the endstage kidney in a 50-year-old male who died after intermittent maintainance hemodialysis for 10 years was reported. At autopsy, both kidneys were contracted and characterized by grossly visible discrete multiple cysts. Histopathological study of consecutive sections of both kidneys revealed that these cysts were distributed throughout a completely disorganized parenchyma and were composed of dysplastic epithelial cells of different types and of structures, some of which revealed neoplastic transformation.

Humans↗