Biomedical subjects

M Tatsuta

Publications and source records attributed to M Tatsuta.

At least 109 records · Page 6Linked to original sources

PubMed1996

Effect of selective and non-selective muscarinic blockade on baclofen inhibition of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of baclofen, a gamma-amino-n-butyric acid receptor B agonist, on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine and how its effects are influenced by selective (M1) and non-selective (M1 and M2) pharmacological blockade of muscarinic receptors were investigated in inbred Wistar rats. Rats were given s.c. injections of 8 mg/kg body wt baclofen with and without 0.5 mg/kg body wt atropine (non-selective M1 and M2 muscarinic receptor antagonist) or 1.0 mg/kg body wt pirenzepine (selective M1 muscarinic receptor antagonist) every other day after a 25 week carcinogen treatment. At week 52 baclofen significantly decreased the incidence of gastric cancers. Concomitant treatment with atropine significantly attenuated the inhibition by baclofen of gastric carcinogenesis, but combined use with pirenzepine had no significant effect on the inhibition by baclofen of gastric carcinogenesis. Baclofen also significantly decreased the labeling index of the antral mucosa. Baclofen plus atropine attenuated the decrease in the labeling index of the antral mucosa due to baclofen, but baclofen plus pirenzepine had no significant effect on the labeling index. These results suggest that the inhibition of gastric carcinogenesis by baclofen is mediated through muscarinic receptors and M2 receptors, but not M1 receptors, are involved in this response.

Adenocarcinoma↗

PubMed1996

Triamterene suppresses bombesin-enhanced peritoneal metastasis of intestinal adenocarcinomas induced by azoxymethane.

The effects of combined administration of bombesin and the diuretic triamterene on the incidence of peritoneal metastasis of intestinal cancers induced by azoxymethane (AOM) and the labeling index of intestinal cancers were investigated in male inbred Wistar rats. From the start of the experiment, rats were given weekly s.c. injections of AOM (7.4 mg/kg body weight) for 10 weeks and s.c. injections of bombesin (40 micrograms/kg body weight) every other day, and from week 16, s.c. injections of triamterene (10 and 20 mg/kg body weight) every other day until the end of the experiment in week 45. Bombesin significantly increased the incidence of intestinal tumors and cancer metastasis to the peritoneum in week 45. It also significantly increased the labeling index of intestinal cancers. Although administration of both doses of triamterene with bombesin had little or no influence on the enhancement of intestinal carcinogenesis by bombesin, or the location, histologic type, depth of invasion, or labeling index of intestinal cancers, it significantly reduced the incidence of cancer metastasis. These findings indicate that triamterene suppresses cancer metastasis through a mechanism that does not affect the proliferation of intestinal cancers.

Adenocarcinoma↗

PubMed1996

Diagnosis of pancreatic cancer by K-ras point mutation and cytology of pancreatic juice.

OBJECTIVES: Recently, it was reported that detection of K-ras point mutation at codon 12 in pancreatic juice is an objective method for the diagnosis of pancreatic cancer, but a few reports have suggested that this might represent an early event in pancreatic oncogenesis. In the present study we examined, in various patients, the occurrence of K-ras codon 12 point mutation in pancreatic juice and compared it with pancreatic juice cytology, which is also a reliable diagnostic method. METHODS: Pancreatic juice was obtained endoscopically from patients with various pancreatic disorders and those without definite diseases, and was examined cytologically and for the occurrence of K-ras codon 12 point mutation. The K-ras gene was amplified by polymerase chain reaction (PCR) and the mutation at codon 12 (GGT-->GAT) was examined by slot blot hybridization analysis. RESULTS: K-ras point mutation at codon 12 was detected in seven of 14 (50%) pancreatic cancers, in four of 10 (40%) mucin-producing tumors, in four of 13 (31%) chronic pancreatitis, and in two of 10 (20%) pancreas without definite disorders. K-ras point mutation was detected in nine of 18 (50%) pancreatic juice samples containing cancer cells, in eight of 18 (44%) pancreatic juice samples containing atypical cells, but in none of such samples containing only normal cells. CONCLUSION: Cancer cells were detected from pancreatic cancer exclusively, but K-ras point mutation at codon 12 was detected in pancreatic juice, not only from pancreatic cancer, but also from other diseases.

Aged↗

PubMed1996

Development and validation of TMJ viscoelasticity analyzer.

We developed a TMJ viscoelasticity analyzer for non-invasive evaluation of the soft tissues of the TMJ region. We used this device to measure the viscoelastic parameters, viscosity (c), elasticity (k) and mass (m), of the TMJ region for two volunteers. Experiments were performed to determine the optimum measurement conditions for the preload magnitude, head posture and clenching level. We determined measurement variability and carried out statistical analysis by analysis of variance (ANOVA). We found that the values for c and k varied significantly depending on preload magnitudes (p < 0.001). In addition, all parameters varied significantly depending on head posture. However, clenching level did not significantly affect any of the parameters. Measurement variability was below 10% for all parameters. Examination of viscoelasticity of the TMJ region provides valuable information about functional and pathological changes in the soft tissues of this area. In this study, we were able to determine the fundamental characteristics of the TMJ viscoelasticity analyzer and develop methods for examining patients with temporomandibular disorders.

Analysis of Variance↗

PubMed1995

Suppression by amiloride of bombesin-enhanced peritoneal metastasis of intestinal adenocarcinomas induced by azoxymethane.

The effects of concomitant administration of bombesin and of the diuretic drug amiloride on the development of large and small intestinal tumors induced by azoxymethane (AOM), the incidence of their metastasis to the peritoneum and the labeling index of intestinal adenocarcinomas were investigated in inbred Wistar rats. From the start of the experiment, rats were given weekly s.c. injections of AOM for 10 weeks and s.c. injections of bombesin and/or a higher or lower dose of amiloride hydrochloride (amiloride) every other day until the end of the experiment in week 45. Administration of bombesin significantly increased the incidence of intestinal tumors and cancer metastasis to the peritoneum in week 45. It also significantly increased the labeling index of intestinal adenocarcinomas. Although administration of both doses of amiloride with bombesin had little or no influence on the enhancement of intestinal tumorigenesis by bombesin, the location, histological type, depth of involvement or labeling index of intestinal adenocarcinomas, a higher dose of amiloride significantly reduced the incidence of cancer metastasis to the peritoneum. Our findings indicate that amiloride possesses an anti-metastatic activity.

Adenocarcinoma↗

PubMed1995

Promotion by substance P of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of prolonged administration of neuropeptide substance P (SP) on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on the labeling index of gastric mucosa were investigated in Wistar rats. Rats received subcutaneous injections of 12 micrograms/kg body weight of SP every other day after 25 weeks of oral treatment with MNNG. Long-term administration of SP significantly increased the incidence of gastric cancers in week 52. However, it did not affect the histological type and depth of involvement of gastric cancers. SP also caused a significant increase in the labeling index of the antral and fundic epithelial cells in week 52. These findings indicate that SP promotes gastric carcinogenesis and suggest that this effect may be related to its stimulation of antral epithelial cell proliferation.

Animals↗

PubMed1995

Effectiveness of the cytologic examination of pure pancreatic juice in the diagnosis of early neoplasia of the pancreas.

BACKGROUND: The early diagnosis of pancreatic carcinoma through the use of traditional radiographic or ultrasonographic methods is extremely difficult. METHODS: To detect an early and potentially curable cancer of the pancreas, endoscopic retrograde pancreatography (ERP) and aspiration cytology of pure pancreatic juice were performed in 295 consecutive patients who had symptoms or findings that suggested pancreatic disease but in whom there was neither a pancreatic mass nor ductal stenosis. RESULTS: Positive cytologic results were obtained in 12 patients (4%). With the aid of intraoperative cytodiagnosis, all 12 early neoplasms of the pancreas were successfully resected. Of these 12 resected specimens, 4 were adenocarcinoma with minimal invasion, 3 were in situ adenocarcinoma and 5 were marked atypia. All 12 patients were alive with no evidence of recurrence for an average of 32 months after surgery. The 283 patients who had negative ERP-cytology results were observed, but no further cases of pancreatic cancer were found. CONCLUSIONS: Because ERP-cytology is simple to perform, safe, and reliable, it is useful in the diagnosis of patients who have early neoplasm of the pancreas.

Aged↗

PubMed1995

Enhancement by peptide histidine isoleucine of experimental carcinogenesis in the colon of rats induced by azoxymethane.

The effects of peptide histidine isoleucine (PHI) on the incidence and histology of colon tumors induced by azoxymethane (AOM), and on the labeling index of colon mucosa were investigated in Wistar rats. Rats received weekly s.c. injections of 7.4 mg/kg body weight of AOM for 10 weeks, and of 1.0 or 4.0 nmol/kg body weight of PHI until the end of the experiment in week 35. Administration of PHI at the higher, but not the lower dosage, significantly increased the incidence of colon tumors. PHI had no influence on the histology of colon tumors or adenocarcinomas. It also caused significant increase in the labeling index of colon epithelial cells. These findings indicate that PHI enhances colon carcinogenesis, and that its effect may be related to increasing proliferation of colon epithelial cells.

Adenocarcinoma↗

PubMed1995

Attenuation of vasoactive intestinal peptide enhancement of colon carcinogenesis by ornithine decarboxylase inhibitor.

The effects of combined administration of vasoactive intestinal peptide (VIP) and the ornithine decarboxylase (ODC) inhibitor, 1,3-diaminopropane (DAP), on development of colon tumors induced by azoxymethane (AOM), on ODC activity of the colon wall, and on the labelling index of colon epithelial cells were investigated in inbred Wistar rats. Rats received weekly subcutaneous injections of AOM for 10 weeks and subcutaneous injections of VIP every other day and drinking water containing DAP (2.5 milligrams) ad libitum until the end of the experiment at week 45. Administration of VIP significantly increased the incidence of colon tumors at week 45. It also resulted in significant increases in colon ODC activity and in the labelling index during administration of AOM, but not after its cessation. Administration of both DAP and VIP significantly reduced the enhanced colon carcinogenesis by VIP. The DAP significantly attenuated the VIP enhancement of colon ODC activity and of the labelling index during AOM administration. These findings indicate that ODC inhibition attenuated enhancement of colon carcinogenesis, and suggest that enhancement of colon carcinogenesis by VIP may be mediated through its polyamine biosynthesis.

Adenocarcinoma↗

PubMed1995

Chemoprevention by galanin against colon carcinogenesis induced by azoxymethane in Wistar rats.

The effects of the neuropeptide galanin on the development of colon tumors induced by azoxymethane (AOM) and on the labeling index of colon epithelial cells were investigated in Wistar rats. Treatment with galanin significantly decreased the incidence of colon tumors at week 45. Galanin did not influence the histological appearance of the colon tumors, but it slightly increased the frequency of sub-mucosal adenocarcinomas. Furthermore, it significantly decreased the labeling index of colon mucosa during and after AOM treatment. These findings indicate that galanin inhibited the development of colon tumors and that this effect may be related to its suppression of colon-epithelial-cell proliferation.

Animals↗

PubMed1995

Endoscopic ultrasonography in diagnosis and staging of pancreatic cancer.

The accuracy of endoscopic ultrasonography (EUS) for diagnosis of pancreatic cancers was evaluated in consecutive 232 patients with possible pancreatic cancer, and that for assessment of their locoregional spread was evaluated in 28 patients with pancreatic cancer subjected to pancreatectomy, in comparison with the accuracies of transabdominal ultrasonography (US) and computed tomography (CT). EUS was found to be significantly more accurate than US or CT and was especially useful for detecting small pancreatic cancers of less than 2 cm in diameter. With EUS, pancreatic cancers could be detected as a hypoechoic mass with a relatively unclear margin and irregular internal echoes. EUS was also more sensitive than CT and US for detecting venous and gastric invasions: it was more useful for detecting direct invasion of pancreatic cancers when the tumors were less than 3 cm in diameter. These findings indicate that EUS is an accurate method for diagnosis of pancreatic cancer and assessment of their locoregional spread and is particularly useful for detecting small tumors.

Endoscopy, Digestive System↗

PubMed1995

Liver with hypoechoic nodular pattern as a risk factor for hepatocellular carcinoma.

BACKGROUND/AIMS: Ultrasonography should be used for screening of hepatocellular carcinoma, but there are few reports on the relationship between liver ultrasonographic findings and the development of hepatocellular carcinoma (HCC). Using prospective follow-up studies, we examined the role of liver with a hypoechoic nodular pattern as a high-risk factor in HCC. METHODS: The study was performed by follow-up on 593 patients with chronic liver disease recorded at our hospital. The ultrasonographic pattern of the liver parenchyma was classified either as a small or large hypoechoic nodular pattern or as a nonnodular pattern. Patients were followed up from the time of initial ultrasonographic examination (1985-1987) until January 1, 1991. RESULTS: During the follow-up period (average, 4.2 years, range, 0.3-6.0 years), 62 patients were found to have HCC (12%). Patients whose livers showed small or large hypoechoic nodular pattern had a significantly higher risk of HCC than did patients whose livers showed a nonnodular pattern (rate ratios were 14.0 and 20.0, respectively, adjusted for age, sex, hepatitis virus markers, ICG R15, alpha-fetoprotein concentration, and ultrasonographic pattern of the liver). CONCLUSIONS: Liver showing a hypoechoic nodular pattern is a major risk factor in HCC.

Adult↗

PubMed1995

No effect of RU 486 (mifepristone) on hepatocellular tumorigenesis in orchiectomized male mice induced by 3'-methyl-4-dimethylaminoazobenzene.

Effects of RU 486 (mifepristone) on hepatocellular tumorigenesis in orchiectomized male mice induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) were investigated. Male mice that had been treated with 3'-Me-DAB neonatally were orchiectomized at one month of age, and injected daily with vehicle only or RU 486 at 0.2 or 0.4 mg/day thereafter. In the liver of orchiectomized males injected with vehicle only, adenomatous nodules developed at incidences of 16.2 and 38.5% at 9 and 12 months of age, respectively, but no carcinomas developed at these ages. Injections of RU 486 at 0.2 or 0.4 mg/day neither affect incidences of adenomatous nodules in the liver, their numbers per mouse, and their areas, nor promote the development of carcinomas. The present results suggest that the long term administration of RU 486 has no effects on hepatocellular tumorigenesis.

Animals↗

PubMed1995

Correlation between serum prolactin levels and hepatocellular tumorigenesis induced by 3'-methyl-4-dimethylaminoazobenzene in mice.

Ovariectomy at 1 month of age promotes development of hepatocellular adenomatous nodules in female C57BL/6 x DS-F1 mice treated neonatally with 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). Implantation of oestradiol-17 beta (E2) pellets at 1 month of age suppresses nodule development. Since E2 increases serum levels of prolactin, high serum levels of prolactin in mice that have received implants of E2 pellets may play a role in the suppression of hepatocellular tumorigenesis. Therefore, to investigate the role of prolactin in hepatocellular tumorigenesis, we examined development of adenomatous nodules in female mice that had been treated neonatally with 3'-Me-DAB and had undergone ovariectomy at 1 month of age, under various serum levels of prolactin. Treatment of these mice with perphenazine (dopamine antagonist) from 6 months of age or transplantation of pituitary glands under the renal capsule at 6 months of age markedly increased serum levels of prolactin and significantly suppressed the incidence of adenomatous nodules at 12 months of age. Implantation of E2 pellets at 1 month of age increased serum levels of prolactin to a greater extent and further decreased the incidence of adenomatous nodules. Treatment of mice that had received implants of E2 pellets at 1 month of age with bromocriptine (dopamine agonist) from 6 months of age decreased serum levels of prolactin, and was accompanied by an increase in the incidence of nodules. The present results showed that an increase in serum levels of prolactin was accompanied by a decrease in incidence of liver tumours induced by 3'-Me-DAB in mice, suggesting a suppressive effect of prolactin on liver tumorigenesis in mice. Thus, it is possible that the suppressive effect of oestrogen on liver tumorigenesis in mice is mediated, at least in part, by prolactin.

Adenoma↗

PubMed1995

Chemoprevention by amiloride of experimental carcinogenesis in rat colon induced by azoxymethane.

The effects of amiloride on the incidence and histology of colon tumors induced by azoxymethane, on the labeling index of the colon mucosa and on the activity of ornithine decarboxylase in the colon wall were investigated in Wistar rats. Rats received 10 weekly injections of 7.4 mg/kg body wt azoxymethane and s.c. injections of 5 or 7.5 mg/kg body wt amiloride in depot form every other day for 35 weeks. Prolonged administration of amiloride at a dose of 7.5 mg/kg, but not 5 mg/kg, significantly reduced the incidence of colon tumors at week 35. However, administration of amiloride had little or no significant influence on the histological types of colon tumors and cancers. Administration of amiloride at 7.5 mg/kg significantly decreased the labeling index of the colon mucosa and ornithine decarboxylase activity in the colon wall during and after administration of azoxymethane. These findings suggest that amiloride inhibits development of colon tumors. A possible mechanism of inhibition of colon carcinogenesis by amiloride is its suppression of proliferation of colon tumor cells.

Amiloride↗

PubMed1995

Ornithine decarboxylase inhibitor attenuates NaCl enhancement of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine.

The effects of combined administration of NaCl and the ornithine decarboxylase (ODC) inhibitor 1,3-diaminopropane (DAP) on the incidence and number of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on the ODC activity of the gastric wall and the labeling index of the gastric mucosa were investigated in inbred Wistar rats. Rats were given drinking water with or without 2.5 g/l DAP and chow pellets with and without 10% NaCl ad libitum after 25 weeks of oral administration of MNNG. At week 52 feeding 10% NaCl resulted in significant increases in the incidence of gastric cancers, in the ODC activity of the antral portion of the gastric wall and in the labeling index of antral epithelial cells. Administration of both NaCl and DAP significantly reduced the enhancements by NaCl of gastric carcinogenesis, ODC activity of the antral wall and the labeling index of antral epithelial cells. These results suggest that inhibition of ODC attenuates NaCl enhancement of gastric carcinogenesis and that enhancement by NaCl of gastric carcinogenesis is mediated by polyamine biosynthesis.

Animals↗

PubMed1995

Scanning electron microscopic observations on gastric mucus secretion in rats, and the effects of tetraprenylacetone.

Mucus secretion in the gastric mucosa of rats was studied with a scanning electron microscope. After stimulation, two types of mucus secretion were observed: exocytosis and apical expulsion. Prolonged administration of tetraprenylacetone (TPA) significantly increased the number of mucus-secreting cells in both the gastric corpus and antrum 12 h after the last administration of TPA. In the secreting cells, apical expulsion was significantly more frequent among TPA-treated than in untreated rats. TPA also significantly increased the hexosamine concentration in both gastric corpus and antrum. These findings indicate that TPA stimulates both the content and the secretion of gastric mucus, and that its secretion is chiefly through apical expulsion.

Animals↗

PubMed1995

Effects of Helicobacter pylori infection on healing and recurrence of gastric ulcers.

OBJECTIVES: The effects of Helicobacter pylori infection on the healing and recurrence of gastric ulcers were investigated. METHODS: Eighty-five and 17 patients with endoscopically-proven gastric ulcer with and without H. pylori infection, respectively, received 800 mg of cimetidine daily. Healing of ulcer and H. pylori infection were assessed at wk 12. After the 12-wk-treatment period, 67 and 16 patients with healed ulcer positive and negative for H. pylori infection, respectively, received maintenance treatment (cimetidine 400 mg daily). Ulcer recurrence and H. pylori infection were assessed at or within 24 wk from the beginning of maintenance treatment. Variables influencing ulcer healing and recurrence were analyzed by multiple regression analysis. RESULTS: Ulcer healing at wk 12 was similar in patients with and without H. pylori infection, occurring in 16 (89%) of 18 patients without H. pylori infection, compared with 67 (87%) of 77 patients with H. pylori infection. At or within 24 wk from the start of maintenance therapy, ulcer recurrence was significantly more frequent in patients with H. pylori infection than in those without: it occurred in three (20%) of 15 patients without H. pylori infection, but in 37 (58%) of 64 patients with infection. Multiple regression analysis showed that H. pylori infection was related most closely to ulcer recurrence independently. CONCLUSION: H. pylori infection had a significant independent influence on gastric ulcer recurrence, but not initial ulcer healing.

Adult↗