Biomedical subjects
Publications and source records attributed to T Tsuchiya.
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A sensitive mouse lymph node assay (SLNA) is a test method for the detection of contact allergens. The sensitization potential of test chemicals is determined by assessing total lymph node activation response induced by application of the chemical. In this study, we examined whether the SLNA would have a sufficient competence for determination of sensitization capacity of coloured chemicals routinely. Prior to this study, we investigated application of an Alamar Blue dye (non-radioisotope reagent) as an alternative to [3H]thymidine for measurement of cell proliferation. However, the Alamar Blue assay is useful for determining cell number but is not applicable to detect lymph node cell proliferation activity for 24-h culture in the SLNA. The SLNA was applied to evaluate the sensitization capacity of 20 dyes. Most of the sensitizing dyes were correctly determined as a sensitizer. Some chemicals that were known as strong sensitizers showed strong lymph node responses. Comparing the results of the SLNA with data from guinea-pig tests, the same predictions of sensitization capacity were made in nine out of ten cases. The SLNA also detected 13 of the 17 chemicals that were identified to be contact allergens by the human patch test. These data showed that the evaluation of the SLNA was not influenced by the colour property of the test chemicals and that the SLNA was a sufficiently sensitive robust screen test for the identification of contact allergens.
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The absorption, distribution, metabolism, and excretion of 3-(N-formylhydroxylamino) propylphosphonic acid monosodium salt (fosmidomycin), a new antibiotic, were investigated in rats and dogs after i.v. and oral dosing. After i.v. administration of 10 mg/kg of body weight, [14C]-fosmidomycin was excreted mainly in the urine (about 90% of dose within 72 h); and only a little was excreted in the expired air (14CO2) and bile of rats (less than 1% of dose), which suggested the absence of enterohepatic circulation. After oral administration of 10 mg/kg of body weight to rats, 34% and 61% of dose were excreted in the urine and faeces, respectively, suggesting about 30% gastro-intestinal absorption. No metabolites were found by autoradiography of the urine after thin layer chromatography. Radioactivity levels in the serum essentially agreed with the unchanged fosmidomycin levels determined by reverse isotope dilution method. [14C]-fosmidomycin was rapidly distributed in the tissues of rats, and was maintained in high concentration in the liver, kidneys, and bone. The serum level data after i.v. administration closely fitted a 3-compartment open model with first order kinetics after nonlinear least squares regression by NONLIN. The half-lives of the serum level curves for the early, midway, and terminal phases were: 0.13, 0.51, and 17.3 h, respectively in rats; and 0.44, 0.75, and 2.0 h, respectively in dogs.
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Changes of three different cytosolic Ca2+ binding proteins, calbindin-D28k, calretinin, and parvalbumin mRNA expression in the brain of the hamster during aging were investigated by in situ hybridization using brains from hamsters aged 4, 9, 13, 19, to 24 months old. In cerebellum area, calbindin-D28k transcripts showed about 50% to 68% decrease in content in aged-hamster (19 and 24 months old) compared with young (4 months) and adult (9 months), whereas calretinin and parvalbumin mRNA expression remain unchanged throughout the ages examined. Calbindin-D28k gene expression was decreased during aging also in the hippocampus (approximately 60% reduction) and striatum (approximately 25%). In the same areas, striatum and hippocampus, calretinin and parvalbumin mRNA expression in the equivalent sections were not significantly changed with age. These data raise the possibility that CNS calbindin-D28k expression may be selectively down-regulated during aging. The statistically significant decrease of calbindin-D28k mRNA in the normal aging process also suggests and provides further support for the hypothesis that this calcium binding protein may have an important role in neuronal degeneration.
There is speculation that enteroglucagon and peptide YY are responsible for mediating the < > known as a suppressive reaction of upper gastrointestinal motility and transit that is induced by the infusion of nutrients into the ileum. We studied changes in motility and transit in dogs with ileojejunal transposition in which the distal ileum is exposed to undigested nutrients. Nine adult mongrel dogs were equipped with strain gauge force transducers placed on the gastric body, antrum, duodenum, and proximal jejunum. Measurements of gastrointestinal motility, gastric emptying, and plasma levels of total glucagon-like immunoreactivity, immunoreactive glucagon, and peptide YY were obtained both before and after either ileojejunal transposition (5 dogs) or sham operation (4 dogs). Postprandial contractions in the gastric antrum and gastric emptying were significantly inhibited after ileojejunal transposition. The inhibitory effect of ileojejunal transposition on antral motor activity was found to correlate with the rise in plasma total glucagon-like immunoreactivity and peptide YY concentrations. However, plasma glucagon levels were unaffected by ileojejunal transposition. These results suggest that hypersecretion of enteroglucagon and peptide YY induced by ileojejunal transposition inhibits postprandial gastric motor function.
Transforming growth factor alpha (TGF-alpha) is a potent stimulator of normal hepatocyte proliferation, considered to have relationship to the liver regeneration or carcinogenesis. In this study, we investigated immunohistochemically the association between expression of TGF-alpha and cell proliferation activity in mouse hepatoblastomas (HBs) and hepatocellular carcinomas (HCCs) induced in B6C3F1 mice by diethylnitrosamine and sodium phenobarbital. The TGF-alpha-positive rate in HBs (29.2%) was significantly higher than that in HCCs (12.7%). Likewise, the proliferating cell nuclear antigen-positive rate (22.2%) was higher than the HCC value (14.5%). On the individual data for both TGF-alpha and PCNA, most of the HBs showed higher positive rates than HCCs. In HBs, TGF-alpha was localized only in the nuclei, whereas some HCC cells stained positive both in their nuclei and cytoplasm (0.6%). These results suggest expression of TGF-alpha and its localization might be linked to cell proliferation and play a role in malignant progression of mouse HBs.
Methyl methacrylate polymer (PolyMMA) is widely used as the composite resin for the dental plate. During the fabrication process of PolyMMA for the polymerization reaction, benzoylperoxide (BPO) and N,N-dimethyl p-toluidine (DMPT) are added as the initiator and the stimulator, respectively. Because these compounds exhibit toxicity as well as a residue potential, their use raises concerns regarding human safety. The degree of dissolution into serum was determined to evaluate risk to the user. Analysis was by HPLC combined with solid-phase extraction using a C-18 column. The eluted compounds were found to be in the order of 10 to 100 ppm.
Variations in the mitochondrial DNA (mtDNA) of Sika deer (Cervus nippon) from seven localities in Japan were examined to assess the degree of genetic differentiation among subspecies. The entire mtDNA of C. n. centralis, which is about 16,600 base pairs in length, was cloned into plasmids. Using various clones as hybridization probes, we constructed restriction maps of mtDNA for 59 deer and identified six different mtDNA genotypes. The genotypes observed in the subspecies centralis from Honshu Island (the mainland) were distinct from that of the same subspecies from the Tsushima Islands. By contrast, the subspecies yesoensis, which is distributed on Hokkaido Island, shared at least two mtDNA genotypes with the mainland centralis. Analysis of genetic distances showed that Sika deer on the Japanese islands consist of two distinct clusters, namely, the Hokkaido-Honshu (yesoensis-mainland centralis) and the Yakushima-Tsushima (yakushimae-Tsushima centralis) populations. The molecular phylogenetic data obtained for these subspecies do not reflect the present taxonomic status of these subspecies that is based on comparative morphometry. Genetic differentiation of Sika deer in the Japanese islands is a possible example of vicariance.
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To perform continuous ambulatory peritoneal dialysis (CAPD), a safe and easy bag exchange system must be established. The authors developed a new system called "Safedap" and applied it to clinical cases. Safedap consists of a bottom, a sleeve, a shell, and a lock-type connector. The bottom and sleeve are made into one unit with a preembedded sponge saturated with 10% povidone-iodine for disinfection and protection. Safedap was introduced to 23 patients who were observed for a period of 293 patient months. Sixteen patients used a standard spike and functioned as controls. Peritonitis rates were 1/73.3 patient months in Safedap (4 episodes in 3 patients) and 1/30.1 patient months in controls (10 episodes in 7 patients; p less than 0.05). Using life table analysis, the probability of a control being peritonitis free at 12 months was 0.63 versus 0.95 in those using Safedap (p less than 0.05). By allowing completion of bag exchanges safely and rapidly, Safedap is effective in reducing the occurrence rate of peritonitis.
In order to understand the mechanism of clinical worsening in patients with cerebral infarction, attention was focused on the changes in cerebral angiograms obtained repeatedly before and after neurological deterioration. Among 212 stroke patients with minor neurological deficits, incomplete hemiparesis progressed to complete hemiplegia in 15 patients several days after the beginning of symptoms. On admission, 3 had internal carotid artery occlusion, 2 had stenosis of the internal carotid artery, 5 had occlusion of the middle cerebral arterial trunk, 2 had occlusion of the middle cerebral arterial branch, and 3 had no angiographically visible occlusion. The changes between the first and the second angiograms were of different varieties: another recurrent occlusion, progression of occlusion, new occlusion in the cerebral arteries opacified through the collateral pathway, recanalization of the initially occluded artery, and no change. Such different patterns of pathophysiological events show that the mechanism of neurological worsening in infarcted patients is not uniform. Based on the results from the present study, several problems which arose during the investigation and the somewhat vague definition of "progressing stroke" currently in use are discussed.
The authors present two cases of transient occlusion of the major cerebral arteries which occurred during transfemoral catheterization of the carotid artery. Right hemiplegia and aphasia developed suddenly in both cases, and disappeared completely within 14 hours in one case and 25 minutes in the other. On the angiograms performed at the moment of onset of the symptoms, the site of the occlusion was the left internal carotid artery in one case and the left middle cerebral artery in the other. Angiograms which were repeated soon after clinical improvement revealed complete dissolution of the occluding emboli. These cases present direct radiographic evidence that embolic occlusion of a major cerebral artery and its disappearance is the mechanism of the transient manifestation of the neurological deficits associated with cerebrovascular catheterization.
Hepatocellular carcinomas (HCCs) were induced in male Fischer 344 rats with dietary 3'-methyl-4-(dimethylamino)-azobenzene treatment and were classified into solid, glandular (well- or poorly differentiated), and trabecular types. Investigation of cell proliferation kinetics and immunohistochemical localization of transforming growth factor alpha (TGF-alpha) demonstrated all solid (n = 24) and poorly differentiated glandular type (n = 6) HCCs to have TGF-alpha-positive nuclei. Nuclear staining of TGF-alpha was also observed in 13 of 28 (46%) trabecular-type HCCs, whereas 12 (43%) exhibited cytoplasmic staining, and 3 (11%) were negative. As for well-differentiated glandular HCCs, 7 of 20 (35%) were positively stained in their nucleus, another 7 (35%) demonstrated antibody binding in the cytoplasm, and 6 (30%) were negative. The order for growth rate evaluated by bromodeoxyuridine (BrdU) labeling was solid (38.22%), poorly differentiated glandular (26.82%), trabecular (7.98%), and well-differentiated glandular (2.57%) types. For trabecular HCCs with nuclear, cytoplasmic, or negative TGF reactions, values were 13.39% (n = 13), 3.61% (n = 12), and 2.01% (n = 3), respectively. Likewise, BrdU-labeling indices for the counterpart groups of well-differentiated glandular type HCCs were 4.53, 1.91, and 1.29%, respectively. The results indicate that TGF-alpha expression might be linked to histopathological differentiation and cell proliferation in rat HCCs.