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Biomedical subjects

M Ichii

Publications and source records attributed to M Ichii.

44 records · Page 3Linked to original sources
PubMed1984

Photodynamic effects of exposure to hematoporphyrin derivatives and dye-laser radiation on human gastric adenocarcinoma cells.

The phototoxicity of hematoporphyrin derivatives (HPD) and dye-laser radiation on adenocarcinoma cells of the human stomach was examined by light and electron microscopy. Adenocarcinoma cells were obtained from human stomach tissue by endoscopic biopsy. The cells were incubated for 5 minutes in the patient's own serum that contained 0.6 mg HPD/ml and then were exposed to dye-laser radiation at 630 nm at an irradiance of 15 mW/cm2. Electron microscopy showed that cytotoxicity was mediated by mitochondrial damage, dilatation of the rough endoplasmic reticulum, and alterations of the nuclear membrane. The degenerative changes were greater and more frequent in poorly differentiated adenocarcinoma cells than in well-differentiated ones. No marked temperature rise was detected during irradiation. Neither the dye alone nor light alone had any effect. A singlet oxygen-trapping agent, 1,3-diphenylisobenzofuran, prevented adenocarcinoma cell degeneration that otherwise would result from exposure to HPD and dye-laser radiation. Thus singlet oxygen may be the cytotoxic agent in this system.

Adenocarcinoma↗
PubMed1983

Promotion by histamine of carcinogenesis in the forestomach and protection by histamine against carcinogenesis induced by N-nitroso-N-methylnitroguanidine in the glandular stomach in W rats.

The effect of histamine on induction of tumors in the forestomach and the glandular stomach after N-nitroso-N-methylnitroguanidine (MNNG) administration was studied in male inbred W rats. Animals were given 50 micrograms MNNG solution/ml orally for 25 weeks and then 4 mg histamine dihydrochloride sc per day in depot form. Administration of histamine in depot form after MNNG significantly increased the incidence of tumors in the forestomach, but it significantly decreased the incidence of adenocarcinomas in the glandular stomach. All of the tumors induced in the forestomach were of the squamous cell type, and 50% of them were squamous cell carcinomas. Histamine alone had no apparent carcinogenicity in rats.

Adenocarcinoma↗
PubMed1983

Effect of prolonged administration of gastrin on experimental carcinogenesis in rat colon induced by intrarectal instillation of N-methyl-N'-nitro-N-nitrosoguanidine.

The effect of tetragastrin on the incidence and histology of colonic tumors induced by intrarectal instillation of N-methyl-N'-nitro-N-nitrosoguanidine was investigated in Wistar rats. Prolonged administration of tetragastrin in depot form during and after treatment with N-methyl-N'-nitro-N-nitrosoguanidine resulted in a significant reduction in the incidence of colonic tumors in Experimental Week 35. Histological examinations showed that, unlike the well-differentiated adenocarcinomas with a typical glandular pattern in control groups, the adenocarcinomas that developed in rats treated with tetragastrin had high mucin-producing activity.

Adenocarcinoma↗
PubMedDate not supplied

Free radical scavengers suppress the accumulation of platinum in the cerebral cortex.

We investigated whether free radical scavengers and antioxidants inhibit the accumulation of platinum (Pt) in the cerebral cortex. Pt was detected in the cerebral cortex of mice after administration of cisplatin and exposure to short-term hypoxia. When mice were treated with either allopurinol (20 mg/kg) or catalase (100 mg/kg) before cisplatin administration and low oxygen exposure, Pt was not detected in the cerebral cortex. However, Pt was detected in the cerebral cortex of mice pretreated with either a low dosage of allopurinol or heat-denatured catalase. Furthermore, Pt was detected in the cerebral cortex of mice preadministered vitamin C, vitamin E, or deferoxamine. Lipid peroxide levels in the cerebral cortex increased 10 min after the treatment of hypoxia, and peaked 30 min after the treatment. These results suggested that short-term hypoxia produces free radicals, which allows Pt to pass through the blood-brain barrier and accumulate in the cerebral cortex, and that the production of free radicals is reduced by the administration of either allopurinol or catalase, which prevents Pt from passing through the barrier.

Allopurinol↗
PubMedDate not supplied

Age-dependent aluminum accumulation in the human aorta and cerebral artery.

The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries. The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45-99-yr-old; 15 of the subjects were males and 8 were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found. When related to age, two groups were established. Group L (45-75 yr old) and group H (> 75 yr old), which exhibited aortal Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia, Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P) levels (r = 0.801, p < 0.01) and between Al and calcium (Ca) (r = 0.661, p < 0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery. In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation.

Aged↗