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Biomedical subjects

R Hirasawa

Publications and source records attributed to R Hirasawa.

At least 19 recordsLinked to original sources
PubMed2003

Ephemera strigata (Insecta: Ephemeroptera: Ephemeridae) is the intermediate host of the nematodes Rhabdochona denudata honshuensis and Rhabdochona coronacauda in Japan.

Juvenile freshwater parasitic nematodes Rhabdochona denudata honshuensis Moravec and Nagasawa, 1989 and Rhabdochona coronacauda Belouss, 1965 (Spirurida: Thelazioidea: Rhabdochonidae) were found in mayfly nymphs collected in a mountain stream in Japan. Considering the relative density of mayfly nymphs, nematode prevalence, and intensity of parasitism, Ephemera strigata Eaton and Potamanthus formosus Ulmer (Ephemeroptera: Ephemeridae) are frequent natural intermediate hosts for R. d. honshuensis in this locality. The intermediate host of R. coronacauda also is the E. strigata nymph.

Animals↗
PubMed2001

Gene cloning and characterization of alanine racemases from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei.

Alanine racemase genes (alr) from Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei were cloned and expressed in Escherichia coli JM109. All genes encoded a polypeptide of 359 amino acids, and showed more than 99% sequence identities with each other. In particular, the S. dysenteriae alr was identical with the S. flexneri alr. Differences in the amino acid sequences between the four Shigella enzymes were only two residues: Gly138 in S. dysenteriae and S. flexneri (Glu138 in the other) and Ile225 in S. sonnei (Thr225 in the other). The S. boydii enzyme was identical with the E. coli K12 alr enzyme. Each Shigella alr enzyme purified to homogeneity has an apparent molecular mass about 43,000 by SDS-gel electrophoresis, and about 46,000 by gel filtration. However, all enzymes showed an apparent molecular mass about 60,000 by gel filtration in the presence of a substrate, 0.1 M l-alanine. These results suggest that the Shigella alr enzymes having an ordinary monomeric structure interact with other monomer in the presence of the substrate. The enzymes were almost identical in the enzymological properties, and showed lower catalytic activities (about 210 units/mg) than those of homodimeric alanine racemases reported.

Alanine Racemase↗
PubMed2001

Leavening ability of baker's yeast exposed to hyperosmotic media.

To develop a simple and rapid method for enhancing the leavening ability of baker's yeast, we examined the fermentation ability of baker's yeast exposed to hyperosmotic media. When baker's yeast cells were incubated at 25 degrees C for 1 h in a hyperosmotic medium containing 0.5% yeast extract, 0.5% peptone and 20% sucrose, the cells showed a higher fermentation ability in the subsequent fermentation test than those untreated. The increased ratios were from 40 to 60% depending on the strains used. Glucose and fructose showed a similar effect to that of sucrose, but sorbitol was less effective. A high correlation between the intracellular glycerol content and fermentation ability after the osmotic treatment suggested that glycerol accumulated during the hyperosmotic treatment was used in the subsequent fermentation as a substrate, lessened the lag time, and consequently enhanced the fermentation ability. Various baker's yeasts also showed a high leavening ability in dough after the hyperosmotic treatment.

Carbohydrates↗
PubMed2001

Improving the freeze tolerance of bakers' yeast by loading with trehalose.

We examined the freeze tolerance of bakers' yeast loaded with exogenous trehalose. Freeze-tolerant and freeze-sensitive compressed bakers' yeast samples were soaked at several temperatures in 0.5 M and 1 M trehalose and analyzed. The intracellular trehalose contents in both types of bakers' yeast increased with increasing soaking period. The initial trehalose-accumulation rate increased with increasing exogenous trehalose concentration and soaking temperature. The maximum trehalose content was almost identical (200-250 mg/g of dry cells) irrespective of the soaking temperature and the type of bakers' yeast, but depended on the exogenous trehalose concentration. The leavening ability of both types of bakers' yeast loaded with trehalose was almost identical to that of the respective original cells, irrespective of the soaking conditions. The freeze-tolerant ratio (FTR) of both types of bakers' yeast increased with increasing intracellular trehalose content. However, FTR decreased during over-soaking after the maximum amount of trehalose had accumulated. FTR of the freeze-sensitive bakers' yeast was more efficiently improved than that of the freeze-tolerant type.

Freezing↗
PubMed2000

[Interrelationship between disease activity and nutrient intake or serum cytokine in patients with rheumatoid arthritis].

OBJECTIVE: This study was designed to investigate the possibility of nutrition guidance for patients with rheumatoid arthritis (RA). We studied interrelationship between disease activity and nutrient intake or serum cytokine concentration in patients with RA. METHODS: Dietary survey was performed to assess nutrient intake of RA patients. Disease activity parameters, such as weariness index, arthritically index and QOL index were evaluated by self-questionnaire. CRP and serum cytokine concentrations were measured. Interactions between these parameters and nutrient intake were analyzed. RESULTS: In comparison of nutrient intake between patients with RA and healthy controls, RA patients indicated lower ratio of polyunsaturated to saturated fatty acid (P/S) than controls. Preceding with the analysis between disease activity parameter and nutrient intake, RA patients were divided into two groups according to their activities. High weariness group indicated higher lipid intake and energy supplies from fat than low group, suggesting the relationship between disease activity and lipid intake in RA patients. From the comparative study of serum cytokine concentration between patients with RA and healthy controls, RA patients indicated higher concentration of IL-1 beta, IL-6 and IL-8. Serum concentrations of these proinflammatory cytokines correlated significantly with some nutrient intakes. CONCLUSION: These results imply the relationship between nutrient intake and disease activity in patients with RA. It is important to develop nutrition guidance to improve symptoms for patients with RA.

Arthritis, Rheumatoid↗
PubMed1999

Inhibition by rat C-erbB-2/neu antisense oligonucleotide of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of prolonged administration of a rat C-erbB-2/neu (C-erbB-2) antisense oligonucleotide on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on the labeling and apoptotic indices of gastric cancer was examined in Wistar rats After oral treatment with MNNG for 25 weeks, the rats received intraperitoneal injections of a C-erbB-2 antisense-liposome complex or a sense-liposome complex at a dose of 50 microgram oligonucleotide/kg body weight every other day until the end of the experiment in week 52. In week 52, the incidence of gastric cancers was significantly lover in rats treated with the C-erbB-2 antisense oligonucleotide than in rats treated with the sense oligonucleotide. Administration of the C-erbB-2 antisense oligonucleotide also significantly decreased the bromodeoxyuridine-labeling index and significantly increased the apoptotic index of gastric cancers. The mean cellular fluorescence of gastric antral cells in MNNG-treated rats was positively correlated with the dose of FITC-labeled C-erbB-2 antisense oligonucleotide. Our findings indicate that the antisense oligonucleotide inhibits gastric carcinogenesis through decreased cell proliferation and increased apoptosis induction and suggest that antisense strategies may provide new treatment for gastric cancer.

Animals↗
PubMed1999

Low-protein diet promotes sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

Sodium chloride (NaCl) initiates and promotes experimental carcinogenesis in rats. We recently found that a high-protein diet attenuates NaCl-enhanced gastric carcinogenesis in Wistar rats. To investigate the effect of a purified low-protein diet on NaCl-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats, rats were fed a purified diet with an equalized caloric content containing 1% or 2% NaCl and 25% casein (normal-protein diet) or 10% casein (low-protein diet) after oral treatment with MNNG for 25 weeks. In week 52, neither 1% nor 2% NaCl had a significant effect on gastric carcinogenesis in rats fed a normal-protein diet. However, oral administration of 2%, but not 1%, NaCl significantly increased the incidence of gastric cancers in rats fed a low-protein diet. Oral administration of 2% NaCl also significantly increased the bromodeoxyuridine (BrdU)-labeling index and the ornithine decarboxylase (ODC) activity and decreased apoptosis of gastric cancers in rats fed a low-protein diet. However, 2% NaCl had no significant effect on these three parameters in rats fed a normal-protein diet. These findings indicate that a low-protein diet enhances the effect of NaCl in gastric carcinogenesis and that this enhancement may be mediated by increased cell proliferation and reduced apoptosis of gastric cancers.

Adenocarcinoma↗
PubMed1999

Attenuation by all-trans-retinoic acid of sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of prolonged administration of all-trans-retinoic acid (RA) on sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine, and the labelling and apoptotic indices and immunoreactivity of transforming growth factor (TGF) alpha in the gastric cancers was investigated in Wistar rats. After 25 weeks of carcinogen treatment, the rats were given chow pellets containing 10% sodium chloride and subcutaneous injections of RA at doses of 0.75 or 1.5 mg kg(-1) body weight every other day. In week 52, oral supplementation with sodium chloride significantly increased the incidence of gastric cancers compared with the untreated controls. Long-term administration of RA at both doses significantly reduced the incidence of gastric cancers, which was enhanced by oral administration of sodium chloride. RA at both doses significantly decreased the labelling index and TGF-alpha immunoreactivity of gastric cancers, which were enhanced by administration of sodium chloride, and significantly increased the apoptotic index of cancers, which was lowered by administration of sodium chloride. These findings suggest that RA attenuates gastric carcinogenesis, enhanced by sodium chloride, by increasing apoptosis, decreasing DNA synthesis, and reducing TGF-alpha expression in gastric cancers.

Adenocarcinoma↗
PubMed1999

Increase in apoptosis and decrease in ornithine decarboxylase activity of the gastric mucosa in patients with atrophic gastritis and gastric ulcer after successful eradication of Helicobacter pylori.

OBJECTIVE: Recent reports have shown that patients infected with Helicobacter pylori (H. pylori) have a higher risk of gastric cancer. However, the mechanism of this increased risk is still unclear. In the gastric mucosa, the size of a continuously renewed population of cells is determined by the rates of cell production and of cell loss. Ornithine decarboxylase (ODC) activity is elevated in various gastrointestinal cancers and serves as a marker of mucosal proliferative activity. Apoptosis occurs throughout the gut and is associated with cell loss. Both cell proliferation and cell loss have important roles in H. pylori-associated gastric carcinogenesis. Therefore, we investigated the effect of H. pylori eradication on ODC activity and apoptosis in the gastric mucosa of patients with atrophic gastritis and gastric ulcers. METHODS: Biopsy specimens of the gastric antrum were obtained at endoscopy from 17 H. pylori-positive gastric ulcers patients and 15 H. pylori-positive gastritis patients before and 4 wk after eradication therapy with amoxicillin, omeprazole, and a new anti-ulcer agent, ecabet sodium, and from 10 gastric ulcer patients in whom ulcer healed but H. pylori was left untreated. ODC activity and induction of apoptosis were determined immunohistochemically. RESULTS: H. pylori was successfully eradicated with the triple therapy in 12 (80%) of 15 gastritis patients and 13 (76%) of 17 gastric ulcer patients. ODC activity was present in the gastric mucosa in 21 (84%) patients before eradication but in only four (16%) patients after successful eradication (p = 0.0005). The apoptotic index increased significantly (p = 0.0006) from 4.2% +/- 0.4% before treatment to 7.4% +/- 0.5% after successful eradication. CONCLUSIONS: Successful eradication of H. pylori decreases mucosal ODC activity and increases apoptosis in the gastric mucosa. These findings indicate that by decreasing mucosal cell proliferation and increasing epithelial cell loss, H. pylori eradication may help decrease the subsequent risk of gastric cancer.

Adult↗
PubMed1998

Alpha1-adrenoceptor stimulation enhances experimental gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of prolonged administration of the norepinephrine-mimicking agent metaraminol, the alpha1-adrenergic agonist phenylephrine and the alpha2-adrenergic agonist clonidine on the incidence of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), the ornithine decarboxylase activity of the gastric cancer and the labeling index of the gastric mucosa were investigated in Wistar rats. Rats received s.c. injections of metaraminol, phenylephrine or clonidine every other day after 20 weeks of oral treatment with MNNG. At week 52, administration of metaraminol and phenylephrine at the higher dose significantly increased the incidence of gastric cancers, the ornithine decarboxylase activity of the gastric cancers and the labeling index of the antral epithelial cells. Administration of phenylephrine at the lower dose and clonidine at both doses had no significant effect on the incidence of gastric cancers, the ornithine decarboxylase activity of the gastric cancers or the labeling index of the gastric mucosa. Our results suggest that adrenoreceptor stimulation enhances gastric carcinogenesis and that such enhancement is mediated through alpha1-adrenoceptors without alpha2-adrenoceptor involvement.

Adrenergic alpha-Agonists↗
PubMed1998

Attenuation by methionine of monochloramine-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

Helicobacter pylori appears to play a major role in the development of gastric cancer in humans. The mechanism behind the carcinogenic or co-carcinogenic effects of H. pylori has not been established. Ammonia, generated by urea from H. pylori, has been studied as a possible cause. However, the ammonia-monochloramine system has been shown to play a more important role in H. pylori-associated mucosal injury. Therefore, the effects of combined administration of monochloramine and methionine, singly or together, on the development of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in inbred Wistar rats. After receiving oral MNNG and regular chow pellet for 25 weeks, rats received regular chow pellets or chow pellets containing 20% ammonium acetate, and normal tap water or water containing 30 mM sodium hypochlorite, with or without a subcutaneous injection of methionine, until the end of the experiment (week 52). Treatment with both ammonium acetate and sodium hypochlorite, which produce monochloramine, significantly increased the incidence of gastric cancers in week 52, whereas the concomitant administration of methionine with ammonium acetate and sodium hypochlorite significantly attenuated such enhanced gastric carcinogenesis. Spectrophotometric examination revealed that methionine scavenged monochloramine. Our findings suggest that H. pylori-associated gastric carcinogenesis may be mediated by monochloramine.

Animals↗
PubMed1998

Effectiveness of premedication with pronase for improving visibility during gastroendoscopy: a randomized controlled trial.

BACKGROUND: Minute early gastric cancers can be removed with endoscopic mucosal resection techniques. However, early detection of these minute cancers with endoscopy is still difficult. For this purpose, use of a dye is helpful. To increase visibility further, gastric mucus should be removed before endoscopic examination. In this study, the effectiveness of premedication with pronase for improving visibility during gastroendoscopy was investigated. METHODS: From January through July 1996, outpatients scheduled for gastroendoscopy were randomly assigned to oral premedication with the antifoam agent dimethylpolysiloxane alone (n=34), with dimethylpolysiloxane plus sodium bicarbonate (n=32), or with dimethylpolysiloxane, sodium bicarbonate, and pronase (n=34). All were given about 10 minutes before the start of endoscopy. After inserting the endoscope, the endoscopist gave visibility scores at conventional endoscopy and after methylene blue spraying. RESULTS: Premedication with pronase significantly improved visibility before and after methylene blue spraying as compared with the two other groups pretreated without pronase. Pronase also significantly shortened the times for chromoendoscopic examination. Pronase had no significant effect on the culture of Helicobacter pylori. CONCLUSION: Premedication with pronase improved endoscopic visualization during conventional endoscopy and chromoendoscopy. Its routine use at gastroendoscopy is therefore recommended.

Adult↗
PubMed1998

Low prevalence of Helicobacter pylori infection in patients with hamartomatous fundic polyps.

Helicobacter pylori infection of the gastric mucosal surface was investigated in patients with hamartomatous fundic polyps or hyperplastic polyps and in patients without endoscopic evidence of disease (healthy subjects). Presence of H. pylori infection was determined by culture, histologic examination, and the endoscopic phenol red test. Adherence of H. pylori was evaluated with scanning electron microscopic examination of antral biopsy specimens. Both prevalence of H. pylori infection (P < 0.001) and H. pylori adherence (P < 0.05) were less in patients with hamartomatous fundic polyps than in healthy subjects and patients with hyperplastic polyps. However, the percentages of plasma cells in gastric mucosa that contained IgA and of gastric epithelial cells that expressed Lewis b did not differ significantly among the three groups. These findings suggest that defense mechanisms against the attachment of H. pylori other than IgA or Lewis b antigen are present in patients with hamartomarous fundic polyps.

Biopsy↗
PubMed1998

Inhibition by transforming growth factor (34-43)-alpha, a TGF-alpha antagonist, of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of prolonged administration of transforming growth factor (34-43)-alpha, an antagonist of TGF-alpha, on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on the labelling and apoptotic indices and TGF-alpha immunoreactivity of gastric mucosa and gastric cancers was examined in Wistar rats. The rats received intraperitoneal injections of 10 or 20 microg kg(-1) body weight of TGF(34-43)-alpha every other day after oral treatment with MNNG for 25 weeks. Long-term administration of TGF(34-43)-alpha at both doses significantly reduced the incidence of gastric cancers at the end of the experiment in week 52. However, TGF(34-43)-alpha had no significant effect on the number, histological type or depth of involvement of gastric cancers. Administration of TGF(34-43)-alpha also significantly decreased the bromodeoxyuridine labelling index and TGF-alpha immunoreactivity, and significantly increased the apoptotic index of antral mucosa and gastric cancers. These findings indicate that TGF(34-43)-alpha inhibits gastric carcinogenesis, and that its effects are mediated through decreased cell proliferation and TGF-alpha immunoreactivity and increased apoptosis induction in the gastric cancers.

Adenocarcinoma↗
PubMed1997

Clinicopathologic features and endoscopic resection of duodenal adenocarcinomas and adenomas with the submucosal saline injection technique.

BACKGROUND: Endoscopic resection with the submucosal saline injection technique has been used to treat early duodenal cancers and adenomas. However, indications for endoscopic treatment of these cancers have not been established. METHODS: We used the submucosal saline injection method to treat 14 early duodenal cancers and adenomas to evaluate its safety and effectiveness. A 0.9% NaCl solution was injected into the submucosal layer near the tumor through needle forceps to elevate the tumor, which was then resected with electrocoagulation. Resected specimens were examined to assess depth of involvement, completeness of resection, and histologic type. Reports of early duodenal cancers in the Japanese literature were reviewed to analyze the relationship among lymph node metastasis, submucosal invasion, and tumor size. RESULTS: All tumors were completely removed "en bloc" (12 tumors) or in a "piecemeal" fashion (two tumors). The largest tumor was 20 mm in diameter. No serious complications occurred during or after treatment. Review of Japanese literature showed that lymph node metastasis did not occur when protruding or elevated tumors were less than 50 mm in diameter but did occur when depressed tumors, with or without marginal elevation, were more than 10 mm in diameter. CONCLUSIONS: Endoscopic resection with the submucosal saline injection technique is a safe and effective treatment for early duodenal cancers and adenomas. Protruding or elevated tumors less than 50 mm in diameter can be removed completely. However, because of possible lymph node metastasis, depressed tumors with or without marginal elevation should be removed surgically.

Adenocarcinoma↗
PubMed1997

A novel method for induction and detection of anaphylactic reaction using the mouse abdominal wall (AW method).

We found that an antigen-specific anaphylaxis was induced by antigen challenge to the abdominal wall, ear auricle, or subcutaneous tissue in mice sensitized 9 days previously with antigen and adjuvant. The anaphylactic reaction was detected by vascular permeability at the injected site 7 minutes after challenge, which was the best time for estimation. A novel method (AW method) for induction and detection of the anaphylactic reaction in mice was established using the abdominal wall as the challenge site. This method could detect the anaphylactic response in mice 1 to 3 weeks after sensitization. The increase in vascular permeability was completely inhibited by administration of diphenhydramine.

Abdominal Muscles↗
PubMed1993

Cerebrospinal fluid corticotropin-releasing hormone and ACTH, and peripherally circulating choline-containing phospholipid in senile dementia.

Cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) and ACTH, plasma levels of ACTH and cortisol, and serum levels of phospholipid and its fractions were determined in samples taken simultaneously from patients with senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID) or dementia following a cerebrovascular accident (CVD), and the borderline-to-normal control subjects. CRH levels in CSF were significantly reduced in patients with SDAT and CVD but not with MID compared to the borderline-to-normal controls. ACTH levels in CSF were significantly reduced in SDAT compared to MID. The levels of circulating lecithin (phosphatidyl-choline) were depressed in a similar fashion to the levels of CRH in CSF in the SDAT patients and the group of severe dementia. Dementia and its severity did not affect the morning plasma levels of ACTH and cortisol. CSF CRH was positively correlated with CSF ACTH, while CSF ACTH was negatively correlated with plasma cortisol. No significant correlations were found between serum lecithin and CSF CRH or ACTH. These findings suggest that: 1) abnormalities in the extrahypothalamic CRH system play a role in the pathophysiology of senile dementia, which may not be specific to SDAT; 2) the CRH system and the ACTH system correlate with each other within the brain; 3) CSF ACTH is subject to the feedback inhibition by circulating cortisol; and 4) in the SDAT patients and the severe dementia group CSF CRH and serum lecithin are reduced probably via independent mechanisms.

Adrenocorticotropic Hormone↗