Biomedical subjects

M Tsuji

Publications and source records attributed to M Tsuji.

At least 37 records · Page 2Linked to original sources

PubMed2001

Induction of neurite outgrowth in PC12 cells by alpha -phenyl-N-tert-butylnitron through activation of protein kinase C and the Ras-extracellular signal-regulated kinase pathway.

The spin trap alpha-phenyl-N-tert-butylnitron (PBN) is widely used for studies of the biological effects of free radicals. We previously reported the protective effects of PBN against ischemia-reperfusion injury in gerbil hippocampus by its activation of extracellular signal-regulated kinase (ERK) and suppression of both stress-activated protein kinase and p38 mitogen-activated protein kinase. In the present study, we found that PBN induced neurite outgrowth accompanied by ERK activation in PC12 cells in a dose-dependent manner. The induction of neurite outgrowth was inhibited significantly not only by transient transfection of PC12 cells with dominant negative Ras, but also by treatment with mitogen-activated protein kinase/ERK kinase inhibitor PD98059. The activation of receptor tyrosine kinase TrkA was not involved in PBN-induced neurite outgrowth. A protein kinase C (PKC) inhibitor, GF109203X, was found to inhibit neurite outgrowth. The activation of PKCepsilon was observed after PBN stimulation. PBN-induced neurite outgrowth and ERK activation were counteracted by the thiol-based antioxidant N-acetylcysteine. From these results, it was concluded that PBN induced neurite outgrowth in PC12 cells through activation of the Ras-ERK pathway and PKC.

Acetylcysteine↗

PubMed2001

Fluorimetric determination of magnesium and aluminum via complexation with oxine in high-performance liquid chromatography.

Aluminum and magnesium were determined by fluorimetric detection via pre-column and/or in-column derivatization with 8-hydroxyquinoline (oxine) in high-performance liquid chromatography. The oxine complex of aluminum was selectively detected when the eluent contained no oxine, whereas the aluminum and magnesium complexes could be simultaneously detected when the eluent contained oxine. The sensitivity was improved by using eluents containing oxine by a factor of 7.1 for aluminum, and the detection limits at S/N=3 were 18 and 16 ng/ml for magnesium and aluminum, respectively. The present system was applied to the determination of magnesium and aluminum in various water samples.

Aluminum↗

PubMed2001

The novel kappa-opioid receptor agonist TRK-820 suppresses the rewarding and locomotor-enhancing effects of morphine in mice.

The effects of the novel kappa-opioid receptor agonist TRK-820 on the rewarding and locomotor-enhancing effects of morphine were investigated in mice. Morphine (1-5 mg/kg, s.c.) caused a dose-related preference for the drug-associated place. In contrast, TRK-820 (0.003-0.03 mg/kg, s.c.) did not produce a significant preference for either compartment of the test box. In combination studies, co-injection of TRK-820 (0.01 and 0.03 mg/kg, s.c.) with morphine significantly suppressed the morphine (5 mg/kg, s.c.)-induced place preference, and this effect of TRK-820 was antagonized by pretreatment with nor-BN1 (3 mg/kg, s.c.), a selective kappa-opioid receptor antagonist. TRK-820 also suppressed morphine-induced hyperlocomotion, and this suppression was also blocked by nor-BNI. These results suggest that TRK-820 suppresses the rewarding and locomotor-enhancing effects of morphine through the activation of kappa-opioid receptors. Thus, we propose that TRK-820 may be useful for controlling pain while reducing undesirable side-effects.

Animals↗

PubMed2001

Prognostic significance of expression of thymidine phosphorylase and vascular endothelial growth factor in human gastric carcinoma.

BACKGROUND AND OBJECTIVES: Both thymidine phosphorylase (dThdPase) and vascular endothelial growth factor (VEGF) are well-characterized inducers of angiogenesis. The purpose of this study was to examine the expression of these antigens and their prognostic significance in gastric carcinoma. METHODS: Medical records of 102 patients with stage II tumor were retrospectively reviewed. Primary tumors were studied by immunohistochemical staining for dThdPase and VEGF. RESULTS: Positive dThdPase expression was observed in 52 (51%) tumors and positive VEGF expression in 53 (52%) tumors. There was a significant correlation between the positive expression of VEGF and lymphatic invasion. The patients with dThdPase-positive carcinoma showed a significantly worse prognosis than those with dThdPase-negative carcinoma in stage II. Moreover, the frequency of hepatic recurrence was significantly higher in the patients with dThdPase-positive and VEGF-positive tumors than in those with dThdPase-negative and VEGF-negative tumors. CONCLUSIONS: Combination analysis of dThdPase and VEGF expression in gastric carcinoma appears to be well-characterized inductors of prognosis and metastasis.

Adult↗

PubMed2001

Gastric T-cell lymphoma presenting with epithelioid granulomas mimicking tuberculosis in regional lymph nodes.

In patients with malignant lymphomas, a sarcoid reaction is occasionally observed. However, lymphoma-related granulomas with caseous necrosis are rare. We describe such a case of T-cell gastric lymphoma that was difficult to diagnose. A 50-year-old man was referred to our hospital because of abnormal gastric endoscopic findings: hypertrophic folds with narrowing of the gastric lumen and multiple ulcers in the body. Gastric biopsy specimens showed non-specific inflammation. An open biopsy of the enlarged gastric regional lymph nodes was performed. The sections revealed effacement of the normal architecture and replacement by numerous epithelioid granulomas accompanied by Langhan's type giant cells with or without central caseous necrosis, strongly suggesting tuberculosis. However, mycobacteria and other causative organisms were not detected, and an anti-tuberculous regimen was ineffective. Repeat gastric biopsies were performed and, finally, atypical lymphocytes were observed infiltrating the mucosa. The patient was diagnosed with gastric T-cell lymphoma based on the results of immunohistochemical stainings. After chemotherapy, a total gastrectomy was performed. The diagnosis of gastric T-cell lymphoma with a sarcoid reaction was confirmed by histological findings of the sections. Namely, the gastric wall was replaced by atypical lymphocytes showing the phenotype of helper T cells, admixed with epithelioid granulomas with Langhan's type giant cells. Thus, this case suggests that regional lymph nodes in gastric lymphomas may be present as epithelioid granulomas with caseous necrosis, mimicking tuberculosis.

Antitubercular Agents↗

PubMed2001

Cyst fluid levels of carcinoembryonic antigen, carbohydrate antigen 19-9, squamous cell carcinoma antigen, and amylase in thyroglossal duct and branchial cleft cysts.

Cyst fluid was aspirated from five thyroglossal duct cysts (TDCs) and four branchial cleft cysts (BCCs). The cyst fluid levels of carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, squamous cell carcinoma antigen (SCC), and amylase were measured and compared between the two types of cyst. The enzyme immunoassay technique was used for CEA and CA19-9, while SCC and amylase levels were measured by the immunoradiometric assay and nitrophenol method, respectively. Immunostaining for CEA, CA19-9, and amylase was also performed. The serum levels of these markers in both groups of patients were within the normal ranges. In contrast, their cyst fluid levels were extremely high. There was no significant difference in the cyst fluid levels of CEA and SCC between the two types of cyst; however, the cyst fluid from the TDCs showed significantly higher levels of CA19-9 and significantly lower levels of amylase compared with that from the BCCs. Immunostaining revealed expression of CA 19-9 in nearly half the columnar epithelial cells in the TDCs, but not in the squamous epithelial cells in the BCCs. CEA and amylase were not found in the epithelial cells of either type of cyst. These findings seem to reflect the difference in etiology between TDCs and BCCs.

Adult↗

PubMed2001

Increased exocytosis of secretory granules in contrast to reduced serum hormone levels in pituitary adenomas of humans and rats treated with dopamine agonist.

The release of secretory granules outside the cells increased in frequency, in inverse proportion to the marked decrease in serum prolactin (PRL) levels in human prolactin-secreting adenomas (PRLomas) treated with bromocriptine (CB), a dopamine agonist. Rat pituitary adenomas induced by diethylstilbestrol also showed an increase in exocytosis of the granules despite a reduction in serum PRL levels after CB treatment. To elucidate this curious phenomenon, which is contrary to current general knowledge that serum hormone levels are sustained by the exocytosis of the secretory granules, we combined morphometric analysis with analyses using a cell fractionation technique and immunocytochemistry. The results indicated that the proteins in secretory granules consisted of 90% nonhormonal proteins and 10% PRL. CB treatment did not change the levels of the former, while the levels of the latter were markedly reduced. Immunocytochemistry, using a protein-A gold method, revealed that the secretory granules in rats treated with CB contained fewer PRL molecules than the controls. Serum PRL elevation caused by the exocytoses, estimated by counting the exocytotic granules, were markedly lower (less than 10%) in CB-treated rats than in the controls. It was suggested that, after CB treatment, the composition of secretory granules altered, or that nonhormonal constituents in the granules disintegrated more slowly, and that the granules became detectable at the site of release for a longer period. Consequently, although granules that appear ultrastructurally similar to those in untreated adenomas are observed to be more frequently released in treated adenomas, it seems that they no longer contribute to raising the serum PRL levels.

Adenoma↗

PubMed2001

Detection of malaria liver-stages in mice infected through the bite of a single Anopheles mosquito using a highly sensitive real-time PCR.

We describe a highly sensitive real-time PCR to detect and measure the development of the liver-stages of malaria parasites in mice infected with sporozoites ranging in number from 25 to more than 164,000, using the same reaction conditions. Furthermore, this assay detects and measures parasite loads in the livers of mice exposed to the bite of a single malaria-infected Anopheles mosquito. This unique method should greatly facilitate studies aimed at evaluating very precisely the efficacy of anti-malarial experimental drug treatments and vaccination regimens in conditions of infection resembling those found in the field.

Animals↗

PubMed2001

Study on the metabolites of 1alpha,25-dihydroxyvitamin D4.

Three major metabolites of 1alpha,25-dihydroxyvitamin D(4) were isolated from the bile of rat and the structures were elucidated on the basis of spectral data and the periodate oxidative cleavage of the diol structures of the metabolites. One of the metabolites was the known calcitroic acid. Another two metabolites were isomers and identified as 9,10-secoergosta-5,7,10(19)-triene-1alpha,3beta,24,25-tetrahydroxy-26-oic acid and 9,10-secoergosta-5,7,10(19)-triene-1alpha,3beta,24,25-tetrahydroxy-28-oic acid. It was found that 1alpha,25-dihydroxyvitamin D(4) is metabolized in a similar manner in vivo to that of 1alpha,25-dihydroxyvitamin D(2) but differently from 1alpha,25-dihydroxyvitamin D(3).

Animals↗

PubMed2001

Peptide-based subunit vaccines against pre-erythrocytic stages of malaria parasites.

Malaria currently ranks among the most prevalent infections in tropical and sub-tropical areas throughout the world with relatively high morbidity and mortality particularly in young children. The widespread occurrence and the increased incidence of malaria in many countries, caused by drug-resistant parasites (Plasmodium falciparum and P. vivax) and insecticide-resistant vectors (Anopheles mosquitoes), indicate the need to develop new methods of controlling this disease. Experimental vaccination with radiation-attenuated sporozoites can protect animals and humans against the disease, demonstrating the feasibility of developing an effective malaria vaccine. However, vaccines based on radiation-attenuated sporozoites are not feasible for large scale application due to lack of in vitro culture system. Therefore, the development of peptide-based subunit vaccines has been undertaken as an alternative approach. Synthetic peptides containing defined B- and T-cell epitopes of different antigens expressed in sporozoites and/or liver stages have been used as subunit vaccines in experimental animal models. They have been shown to be highly immunogenic and capable of inducing protective immunity mediated by antibodies, as well as CD4+ and CD8+ T-cells.

Animals↗

PubMed2001

Protective effects of 5-HT1A receptor agonists against emotional changes produced by stress stimuli are related to their neuroendocrine effects.

1. The effects of the 11beta-hydroxylase inhibitor metyrapone on the protective effects of serotonin (5-hydroxytryptamine; 5-HT)(1A) receptor agonists against emotional changes produced by acute restraint stress were examined in mice. 2. Changes in the emotional state of mice were evaluated in terms of changes in exploratory activity, i.e. total locomotor activity, number and duration of rearing and head-dipping behaviours, and latency to the first head-dipping, using an automatic hole-board apparatus. 3. Treatment with the 5-HT(1A) receptor agonists flesinoxan (1 mg kg(-1), i.p.) and R(+)-2-di-n-propylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT; 1 mg kg(-1), i.p.) 24 h prior to exposure to stress significantly suppressed the decrease in various exploratory behaviours that was observed immediately after the exposure to acute restraint stress (60 min). The effects of flesinoxan (1 mg kg(-1), i.p.) and 8-OH-DPAT (1 mg kg(-1), i.p.) were antagonized by co-injection with N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride (WAY100635; 1 mg kg(-1), i.p.), a selective 5-HT(1A) receptor antagonist. 4. Flesinoxan (1 mg kg(-1), i.p.) and 8-OH-DPAT (1 mg kg(-1) i.p.) significantly increased the plasma corticosterone level, and these effects of 5-HT(1A) receptor agonists were dose-dependently blocked by pretreatment with metyrapone (12.5 and 25 mg kg(-1), s.c.). 5. Metyrapone (25 mg kg(-1), s.c.) alone did not modify the stress-induced changes in exploratory behaviours. Pretreatment with metyrapone (12.5 and 25 mg kg(-1), s.c.) partly antagonized the protective effects of flesinoxan (1 mg kg(-1), i.p.) and 8-OH-DPAT (1 mg kg(-1), i.p.) with regard to only the number and duration of head-dipping behaviours. 6. These results suggest that activation of the adrenocortical system via 5-HT(1A) receptors may facilitate some adaptive mechanism(s) involved in the recognition of and/or ability to cope with stressful situations.

Animals↗

PubMed2001

Human babesiosis in Japan: epizootiologic survey of rodent reservoir and isolation of new type of Babesia microti-like parasite.

We have carried out epizootiologic surveys at various sites in Japan to investigate wild animals that serve as reservoirs for the agents of human babesiosis in the country. Small mammals comprising six species, Apodemus speciosus, Apodemus argenteus, Clethrionomys rufocanus, Eothenomys smithii, Crocidura dsinezumi, and Sorex unguiculatus, were trapped at various places, including Hokkaido, Chiba, Shiga, Hyogo, Shimane, and Tokushima Prefectures. Animals harboring Babesia microti-like parasites were detected in all six prefectures. Inoculation of their blood samples into hamsters gave rise to a total of 20 parasite isolates; 19 were from A. speciosus, and the other 1 was from C. rufocanus. Sequencing of the parasite small-subunit rRNA gene (rDNA) sequence revealed that 2 of the 20 isolates were classified as Kobe type because their rDNAs were identical to that of the Kobe strain (the strain from the Japanese index case). The other 18 isolates were classified as a new type, designated the Hobetsu type, because they all shared an identical rDNA sequence which differed significantly from both that of Kobe-type isolates and that of northeastern United States B. microti (U.S. type). The parasites with Kobe-, Hobetsu- and U.S.-type rDNAs were phylogenetically closely related to each other but clearly different from each other antigenically. The isolates from rodents were demonstrated to be infective for human erythrocytes by inoculation into SCID mice whose erythrocytes had been replaced with human erythrocytes. The results suggest that a new type of B. microti-like parasite, namely, the Hobetsu type, is the major one which is prevalent among Japanese wild rodents, that A. speciosus serves as a major reservoir for both Kobe- and Hobetsu-type B. microti-like parasites, and that C. rufocanus may also be an additional reservoir on Hokkaido Island.

Animals↗

PubMed2001

Human babesiosis in Japan: isolation of Babesia microti-like parasites from an asymptomatic transfusion donor and from a rodent from an area where babesiosis is endemic.

To determine the source of infection for the Japanese index case of human babesiosis, we analyzed blood samples from an asymptomatic individual whose blood had been transfused into the patient. In addition, we surveyed rodents collected from near the donor's residence. Examination by microscopy and PCR failed to detect the parasite in the donor's blood obtained 8 months after the donation of the blood that was transfused. However, we were able to isolate Babesia parasites by inoculating the blood sample into SCID mice whose circulating red blood cells (RBCs) had been replaced with human RBCs. A Babesia parasite capable of propagating in human RBCs was also isolated from a field mouse (Apodemus speciosus) captured near the donor's residential area. Follow-up surveys over a 1-year period revealed that the donor continued to be asymptomatic but had consistently high immunoglobulin G (IgG) titers in serum and low levels of parasitemia which were microscopically undetectable yet which were repeatedly demonstrable by inoculation into animals. The index case patient's sera contained high titers of IgM and, subsequently, rising titers of IgG antibodies, both of which gradually diminished with the disappearance of the parasitemia. Analysis of the parasite's rRNA gene (rDNA) sequence and immunodominant antigens revealed the similarity between donor and patient isolates. The rodent isolate also had an rDNA sequence that was identical to that of the human isolates but that differed slightly from that of the human isolates by Western blot analysis. We conclude that the index case patient acquired infection by transfusion from a donor who became infected in Japan, that parasitemia in an asymptomatic carrier can persist for more than a year, and that A. speciosus serves as a reservoir of an agent of human babesiosis in Japan.

Animals↗

PubMed2001

[Inhibitors of absorption as anti-obesity drugs].

There are two types of anti-obesity agents which are classified as inhibitors of absorption: inhibitors of lipid and carbohydrate absorption. Inhibitors of lipid absorption consist of lipase inhibitor (orlistat, Nomma Herb's extract (CT-II) and fat substitute (olestra, sucrose polyester). Orlistat is now available as an anti-obesity drug in the USA and Europe. CT-II may be useful as a functional diet. Application of fat substitute is still limited in snack food. As for inhibitors of carbohydrate absorption, alpha-glucosidase inhibitors are now available as anti-diabetic drugs. To develop these agents for anti-obesity drug, solution of adverse effects on the gastrointestinal tract are necessary.

Carbohydrate Metabolism↗

PubMed2001

Modification of the effects of benzodiazepines on the exploratory behaviors of mice on a hole-board by diabetes.

The effect of diabetes on the emotional behavior of mice was examined using an automatic hole-board apparatus. Changes in the emotional state of mice were evaluated in terms of changes in exploratory activity; i.e., total locomotor activity, numbers and duration of rearing and head-dipping, and latency to the first head-dipping. The number and duration of head-dipping in diabetic mice were less than those in non-diabetic mice. Diazepam (0.1-0.56 mg/kg, i.p.) dose-dependently increased the number and duration of head-dipping at doses that did not produce sedation in both diabetic and non-diabetic mice. In contrast, methyl-beta-carboline-3-carboxylate (1 and 2 mg/kg, i.p.) decreased the number and duration of head-dipping in non-diabetic mice, but not in diabetic mice. The number and duration of head-dipping in diabetic mice were increased by treatment with flumazenil (0.1 and 0.3 mg/kg, i.v.). These doses of flumazenil did not affect the number or duration of head-dipping in non-diabetic mice. The present data indicate that diabetic mice exhibited anxiety in the hole-board test and that a benzodiazepine receptor antagonist affected the attenuated number and duration of head-dipping in diabetic mice. The heightened anxiety in diabetic mice may be due to the dysfunction of the benzodiazepine receptor and/or of central inhibitory systems.

Animals↗

PubMed2001

Purification and substrate specificity of honeybee, Apis mellifera L., alpha-glucosidase III.

Alpha-glucosidase III, which was different in substrate specificity from honeybee alpha-glucosidases I and II, was purified as an electrophoretically homogeneous protein from honeybees, by salting-out chromatography, DEAE-cellulose, DEAE-Sepharose CL-6B, Bio-Gel P-150, and CM-Toyopearl 650M column chromatographies. The enzyme preparation was confirmed to be a monomeric protein and a glycoprotein containing about 7.4% of carbohydrate. The molecular weight was estimated to approximately 68,000, and the optimum pH was 5.5. The substrate specificity of alpha-glucosidase III was kinetically investigated. The enzyme did not show unusual kinetics, such as the allosteric behaviors observed in alpha-glucosidases I and II, which are monomeric proteins. The enzyme was characterized by the ability to rapidly hydrolyze sucrose, phenyl alpha-glucoside, maltose, and maltotriose, and by extremely high Km for substrates, compared with those of alpha-glucosidases I and II. Especially, maltotriose was hydrolyzed over 3 times as rapidly as maltose. However, maltooligosaccharides of four or more in the degree of polymerization were slowly degraded. The relative rates of the k0 values for maltose, sucrose, p-nitrophenyl alpha-glucoside and maltotriose were estimated to be 100, 527, 281 and 364, and the Km values for these substrates, 11, 30, 13, and 10 mM, respectively. The subsite affinities (Ai's) in the active site were tentatively evaluated from the rate parameters for maltooligosaccharides. In this enzyme, it was peculiar that the Ai value at subsite 3 was larger than that of subsite 1.

Animals↗

PubMed2001

Purification and identification of the essential ionizable groups of honeybee, Apis mellifera L., trehalase.

Trehalase (EC 3.2.1.28) of the bound type was purified as an electrophoretically homogeneous protein from adult honeybees by fractionation with ammonium sulfate, hydrophobic chromatography, and DEAE-Sepharose CL-6B, CM-Sepharose CL-6B, butyl-Toyopearl 650M, and p-aminophenyl beta-glucoside Sepharose 4B column chromatographies. The enzyme preparation was confirmed to be a monomeric protein containing 3.1% carbohydrate. The molecular weight was estimated to be approximately 69,000, and the optimum pH was 6.7. The Michaelis constant (Km) was 0.66 mM, and the molecular activity (k0) was 86.2 s(-1). The enzyme was an "inverting" type which produced beta-glucose from alpha, alpha-trehalose. Dependence of the V and Km values on pH gave values for the ionization constants, pKe1 and pKe2, of essential ionizable groups 1 and 2 of the free enzyme of 5.3 and 8.5, respectively. When the dielectric constant of the reaction mixture was decreased, pKe1, and pKe2 were shifted to higher values of + 0.2 and + 0.5 pH unit, respectively. The ionization heat (deltaH) of ionizable group 1 was estimated to be + 1.8 kcal/mol, and the deltaH value of group 2 was + 1.5 kcal/mol. These findings strongly support the notion that the essential ionizable groups of honeybee trehalase are two kinds of carboxyl groups, one being a dissociated type (-COO(-), ionizable group 1) and the other a protonated type (-COOH, ionizable group 2), although the pKe2 value is high.

Animals↗

PubMed2001

Infectivity and oocyst excretion patterns of Cryptosporidium muris in slightly infected mice.

To determine the infectivity of Cryptosporidium to hosts in slight infections, we examined the infectivity and oocyst output patterns of Cryptosporidium muris in mice inoculated with small numbers of oocysts. One of the 25 ICR mice inoculated with 2.4 x 10(1) oocysts and 19 of the 25 mice inoculated with 2.4 x 10(2) oocysts shed oocysts in the feces after inoculation. Four of the 50 mice inoculated with 2.4 x 10(1) oocysts for 10 consecutive days also shed oocysts and their OPG values were similar to that of the mice which received 2.4 x 10(2) oocysts. Consequently, it is clear that less than 10% of the mice which received 2.4 x 10(1) C. muris oocysts for 10 consecutive days.

Animals↗