Biomedical subjects
Publications and source records attributed to Y Katoh.
A three-bodied in vitro localized wear test investigated the effect of additional heat treatment and thermocycling on localized wear of light-cured composite resin inlays. In only one material did the thermocycling heat treatment have an appreciative positive effect on wear resistance.
The wear of composite resin is influenced by the presence of microcracks on its surface. Recently, it has been shown that surface-penetrating sealants are effective in reducing the wear of posterior composite resin by sealing these defects. The purpose of this study was to investigate the effects of one of these sealants on the wear of various luting agents in conjunction with composite resin inlays. The specimens were subjected to a three-body wear test for 400,000 cycles. The wear values of both composite resin and luting agents were determined by profilometric tracings to the nearest 2 microns. There were no statistically significant differences between the treated and untreated groups as it related to the wear of the luting agents. The wear values of composite resin inlays treated with the sealant, however, were significantly lower than those without treatment, regardless of the type of luting agent used for cementation.
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In 173 patients with operable gastric cancer and in 127 patients with colorectal cancer, the relations between thymidine uptake by cancer cells in semi-solid media, their clinico-pathologic features and survival times, were studied. Multivariate analysis using Cox proportional hazard model showed that thymidine uptake is one of the variables most highly correlated with the probability of patient death. Thus, the availability of thymidine uptake information in the perioperative period may be useful for selecting patients who would benefit from more intensive therapy. Thymidine kinase (TK) is the only enzyme by which thymidine is introduced into the DNA metabolism. In 64 specimens, including gastric and colorectal cancers, TK levels in the serum and tumors were measured accordingly. However, there was no correlation between thymidine uptake and the TK levels, suggesting the necessity of measuring thymidine phosphorylase activity as well.
Acetylcholine is said to be involved in the neuronal transmission of photic information in the suprachiasmatic nucleus (SCN). The purpose of this study was to specify what subtypes of acetylcholine receptors play a major role using in vivo system and to examine the interaction of acetylcholine and excitatory amino acid receptors. To evaluate the effect of a selective agonist or antagonist for the nicotinic or muscarinic receptor on the neuronal transmission in the SCNT, N-acetyltransferase (NAT) activity in the pineal gland was measured after microinjection at this site. In the case of pretreatment with an antagonist, light stimulation was given after 20 min. Carbamilcholine chloride (carbachol) mimicked and only alpha-bungarotoxin (alpha-BTX) blocked the light effect; however, more selective agonists or antagonists were not effective. As for the interaction of these two cholinergic agents with an agonist or antagonist for N-methyl-D-aspartate (NMDA) receptor, alpha-BTX or D-2-amino-5-phosphonovalerate (D-APV) significantly blocked the suppressive effect of NMDA or carbachol, respectively. These data suggest that classical acetylcholine receptors do not play a direct role in neuronal transmission of photic information in the SCN in rats.
Gastric epithelium is exposed not only to oxidants generated within the lumen, but also to those produced by ischemia/reperfusion. This study examined the mechanism(s) of oxidant-induced injury to cultured rat gastric mucosal cells, and characterized the antioxidant profile of these cells. Hydrogen peroxide (H2O2), generated by glucose oxidase, damaged cells dose-dependently, as assessed by increased leakage of labeled 51Cr. Glucose oxidase-induced damage was prevented by exogenous catalase (but not by exogenous superoxide dismutase). Chelation of cellular iron with desferrioxamine or phenanthroline specifically protected cells against H2O2, whereas binding of extracellular iron with apotransferrin failed to. Disruption of the glutathione redox cycle at three independent sites rendered cells less resistant to H2O2, whereas inhibition of cellular catalase did not result in sensitization of cells to H2O2. In conclusion, (1) oxidant injury induced by extracellular H2O2 is mediated by intracellular iron; (2) extracellular superoxide is not involved in the damaging process; and (3) the glutathione redox cycle plays a principal role in detoxifying H2O2 as a cellular antioxidant in cultured gastric mucosal cells.
The mutagenic activity of 5-azacytidine (azaC) was assayed in heterozygous soybean plants (Y11y11), according to the appearance of mutational spots (yellow, dark green and twin) on the leaves. When soybean seeds were treated with azaC at 10-100 micrograms/ml, azaC was found to be significantly mutagenic and to exert heritable effects in the soybean test system. Treatment with azaC increased the frequency of twin spots on the leaves. AzaC would thus appear to cause somatic crossing over as its major effect.
A 67-year-old man with squamous cell bladder carcinoma showed remarkable leukocytosis (maximum 50,300 per microliter.) for 4 months while the neoplasm recurred and metastasis progressed. The patient died of systemic metastasis within 9 months after cystectomy. Enzyme immunoassay of the serum demonstrated remarkably high levels of granulocyte colony-stimulating factor (4,928 pg./ml.). Immunohistochemical examination with anti-granulocyte colony-stimulating factor monoclonal antibody demonstrated granulocyte colony-stimulating factor production in the metastatic cancer cells in the liver. The expression of the granulocyte colony-stimulating factor gene in the tumor specimens was examined by standard Northern blot analysis. Specific granulocyte colony-stimulating factor transcript was identified in the total ribonucleic acid fraction extracted from a tumor specimen of the peritoneal metastatic lesion. These results indicated that the autonomous production of granulocyte colony-stimulating factor in this bladder carcinoma induced paraneoplastic leukocytosis.
Leukocytosis sometimes accompanies malignant neoplasms in the absence of infection. It is thought that the production of colony-stimulating factor by neoplasms is the most potent cause of tumour-induced leukocytosis; several mechanisms have been suggested to explain this. We examined 155 human tumour xenografts established in nude mice, and found that 17 of the xenografts induced remarkable leukocytosis (> 15,000 microliters-1) in nude rats. We examined granulocyte colony-stimulating factor (G-CSF) production by the xenografts to study the mechanisms underlying this tumour-induced leukocytosis. Ten of the 17 xenografted human tumours appeared to express the G-CSF gene. Serum G-CSF increased, to concentrations of 179-37,218 pg ml-1, in host animals transplanted with the ten xenografts expressing the G-CSF gene transcripts. The biological activity of serum G-CSF also increased, to concentrations of 206-9,074 pg ml-1, in the host animals transplanted with the ten xenografts. Immunohistochemical analysis demonstrated G-CSF production at the cellular level in three of the ten xenografts. These results suggested that the production of G-CSF is a common event in human tumour xenografts associated with leukocytosis, but that factors other than G-CSF are also likely to be involved. Leukocytosis induced by neoplasms seems to be a heterogeneous and complex disorder.
The Dental Aesthetic Index (DAI) was used to evaluate malocclusion in Japanese high school students (n = 409, ages 15-18 yr). The purpose of this study was to obtain basic data concerning malocclusion in Japanese high school students. This study used a sample of students from randomly selected urban and rural high schools in Japan's Kyushu district. The DAI scores for urban and rural high school students, as well as the total DAI scores from these two areas were significantly higher than that of American high school students. These results showed that the number of students with an acceptable dental appearance among Japanese high school students is significantly lower than among American high school students. This indicates a higher need for orthodontic treatment among Japanese high school students.
Since the opening of our clinic 117 years before, we have treated 62 cases of primary hyperparathyroidism (PHPT), among which there were 6 cases (1 male, 5 females) whose calcium levels fell within the normal range. However, in all these cases the serum ionized calcium (Ca++) levels and the serum ionized calcium/calcium ratio (Ca++/Ca ratio) were high. Moreover, in comparing them with hypercalcemic patients (56 cases), the serum Ca++ levels were significantly lower, but the (Ca++/Ca ratio) was significantly higher. Also, the excised weight of 606.1 +/- 520.3 mg was significantly smaller than that of hypercalcemic patients, which was 1,967.9 +/- 2,086.3 mg. Preoperative locations showed significantly lower levels in comparison with hypercalcemic patients by all methods including computed tomography (CT), ultrasonography, scintigraphy, and magnetic resonance imaging (MRI). In normocalcemic patients following parathyroidectomy, although the decrease in serum calcium levels was not significant, the serum Ca++ levels and the Ca++/Ca ratio decreased significantly, so that not only are they useful parameters for preoperative diagnosis of PHPT, but they are also considered necessary and indispensable for observation of the post-operative course and judging therapeutic effects including the operation. Based on our study we concluded that in multiple and recurrent stone formers with normal range of serum Ca levels, regardless of the presence or absence of local diagnosis, if the serum Ca++ level and Ca++/Ca ratio are high, existence of primary hyperparathyroidism must be suspected, and adequate treatments should be instituted promptly.
Adaptation of eight kinds of resin restorations on Class V enamel cavity, cement-enamel-junction (CEJ) cavity and root surface cavity were compared. Extracted human premolars were used as experimental specimens. Restored specimens were divided into two groups; short storage group of 2 week duration and long storage group of 6 month duration. The specimens were thermal cycled during storage. After that replicas of the vertical sections were made for examination by SEM and the gaps measured from photographs. The appearance and width of gaps between resin and cavity walls were characterised by the type of cavity and the filling materials. In Class V enamel cavity, gaps were observed on the cavity floor, whilst almost none was observed in other areas showing good adaptation. In the CEJ cavity, gaps appeared only at the cavity floor and gingival wall. In the root surface cavity, gaps were observed on all cavity walls with smaller widths on the occlusal wall and greater width on the cavity floor. Clearfil-F and Clearfil-F II showed fine adaptation on all cavities in general, especially on the dentinal cavity wall. Almost all the materials showed a tendency to form gaps which was found to increase with time. The difference in width, however, varied with the materials used.
We have experienced 5 cases of septic shock induced by extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrostomy. We suspected 5 causes of septic shock; severe hydronephrosis, nephrostomy tube itself, an increase of intrarenal pressure, bacteria in urinary stone, and hepatic failure. Based on the above suspected causes of septic shock, we suggested 3 prophylactic treatments for septic shock; a preventive administration of antibiotics before ESWL and percutaneous nephrostomy, proper management of nephrostomy tube, and early diagnosis and treatment for septic shock.
Tibial condyles in 11 patients with knee joint osteoarthrosis were analyzed by subchondral bone morphometry using 11 static parameters. The results were evaluated by comparison with the grade of joint cartilage degeneration in relation to the external, intermediate, and internal areas of the tibial condyle. The bone morphometric data also were analyzed according to the depth of layers, from the surface to the depth of 2000 microns of the bone. A parallel relationship between the bone volume/bone formation activity and the Mankin grade of cartilage degeneration was noted in both medial and lateral condyles. Bone resorption activity in the medial condyle was found only in the external and intermediate areas; it was extremely low in the lateral condyle. Throughout the observation areas, the values of bone volume in relation to depth were highest in the superficial layer with a gradual decrease as the depth increased. The bone formation activity was highest in the superficial layer in the lateral condyle, whereas in the medial condyle, it was highest in the layer between 1000 and 1500 microns in depth. The bone resorption activity showed no variations according to the depth. The progression of joint cartilage degeneration was associated with remodeling of the underlying subchondral bone.
The dnaJ deletion mutant K7052(lambda dnaK) has a temperature-sensitive defect in the synthesis of beta-galactosidase. We confirmed this operon-specific and temperature-sensitive defect in cell-free extracts prepared from the mutant cells and found that the missing factor was CRP. In the mutant, the cellular concentration of CRP was too low to allow the expression of the lac operon at a nonpermissive temperature. Introduction of a CRP over-producing plasmid into the dnaJ deletion mutant suppressed the defect of beta-galactosidase synthesis. The lower content of CRP in the mutant was found to result from extreme instability of the protein. These results strongly suggested that the heat shock protein dnaJ is involved in the stabilization (or degradation) of CRP.
The mutagenic activity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was assayed in heterozygous soybean plants (Y11y11), based on the appearance of mutational spots (yellow, dark green and twin) on the leaves. When soybean seeds were treated with IQ at concentrations of 0.01-0.1 microgram/ml, the frequency of mutational spots per leaf increased significantly in proportion to the concentration of IQ. At higher concentrations IQ was toxic. The mutagenicity of IQ was enhanced by pretreatment with the hepatic S9 fraction from Aroclor-induced rats. The numbers of yellow and dark green spots per leaf increased markedly by the treatment with IQ and S9-activated IQ, but the number of twin spots did not increase.
A total of 556 patients with 769 intracranial aneurysms, of which 256 were unruptured and 513 were ruptured, were included in the present study. The patients were divided into three age groups: those aged 59 years or younger, those aged 60 to 69 years, and those aged 70 years or older. Small aneurysms of 4 mm or less in diameter were more common in the series of unruptured aneurysms than in the ruptured aneurysms. The rupture rate in anterior communicating artery aneurysms was the highest, and it increased with age. A follow-up study was performed on 47 patients with 55 unruptured aneurysms, and only one giant basilar artery aneurysm ruptured during the average follow-up period of 5.2 years. Direct operation was performed on 52 patients with unruptured aneurysms. While the surgical mortality rate was 0%, the morbidity rate was 6% (three of 52 cases), which was not directly related to the patients' age. When considering surgery for unruptured aneurysms, rupture rate of aneurysms at each site is one of the most important factors, especially in elderly patients.
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