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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 505 records · Page 28Linked to original sources
PubMed1990

[Effect of inner ear immune response on the caloric nystagmus in guinea pigs].

The effect of direct antigen (KLH) challenge of endolymphatic sac (e. sac) on caloric response was investigated in guinea pigs. The caloric response was not significantly suppressed both in the primary KLH challenged ears and in the PBS challenged ears as compared to the unchallenged contralateral ears. In the animal of secondary KLH challenge of the e. sac, the caloric response was significantly reduced in the challenged ears as compared to the unchallenged contralateral ears and to the PBS challenged ears. These result suggested that local immune reaction mounted in the e. sac caused immune injury not only to the e. sac but also to the vestibular function.

Animals↗
PubMed1990

Modulation of rat salivary carbonic anhydrase by pilocarpine.

Carbonic anhydrase (CA) from pilocarpine-treated (1.5 mg/kg body weight; i.p.) rat saliva was purified by inhibitor affinity chromatography. The purified CA contained Mr 42000 and 39000 proteins on sodium dodecyl sulfate polyacrylamide gel electrophoresis. In addition to the erythrocyte isozyme (Mr 30000), salivary gland CA from rats without pilocarpine stimulation contained Mr 39000 and 33000 proteins and that from rats with pilocarpine stimulation also contained Mr 42000 protein. The 42000Da and 39000Da proteins bound to concanavalin A and were cleaved by endo-beta-N-acetylglucosaminidase F to become 39000Da and 33000Da proteins. These results suggest that, under the influence of pilocarpine, salivary gland cells synthesize a new glycoprotein, Mr 42000, via N-linked glycosylation of a 39000Da glycoprotein, which is the only secretory glycoprotein in the unstimulated salivary gland and is produced by N-linked glycosylation of a 33000Da polypeptide.

Animals↗
PubMed1990

[SEM investigations on the human sclerosed dentinal tubules].

Sclerotic changes of dentinal tubules appeared in the dentin beneath the carious, attrition and abrasion lesions and in the transparent root dentin were investigated using the scanning electron microscopy. 1) Shape of crystal-like substances appeared in the dentinal tubules could not be closely related to kinds of dentin destruction. 2) In the dentinal tubules beneath the carious lesions, cuboidal or rhomboid-shaped, short rod-like, long rod-like, plate-like and droplet-like crystals were mainly observed. Combination of cuboidal or rhomboid-shaped and short rod-like crystals or that of long rod-like and plate-like crystals were most frequently observed. 3) In the dentinal tubules beneath attrition and abrasion lesions, cuboidal or rhomboid-shaped, short rod-like and droplet-like crystals were mainly observed, however, the size of cuboidal or rhomboid-shaped crystal was usually smaller than that observed beneath carious lesion and they deposited compactly within the tubules. 4) In the sclerosed dentinal tubules in the transparent root dentin, compact deposition of rhomboid-shaped and irregular sand-like crystals were usually observed. Size of rhomboid-shaped crystal is smaller than that observed beneath carious lesion. The deposit of sand-like crystal in the tubules was easily discriminated from the matrix of peritubular dentin. 5) In any case, the kinds of crystals and pattern of deposition were not necessarily same between the neighboring tubules. However, in a tubule, they were almost same in shape and mode of deposition throughout the entire length of tubule from the outer side to the pulpal side. These facts seem to indicate that mineral deposition within the tubule due to sclerosis is performed under individual condition. 6) Finding showing biological control of mineral deposition within the dentinal tubules by the odontoblasts could not be observed.

Calcinosis↗
PubMed1990

[Adjuvant chemotherapy of osteosarcoma].

Osteosarcoma is the one of the tumors that's prognosis have been improved dramatically by the introduction of chemotherapy consisting mainly of adriamycin, high-dose methotrexate with Leucovorin rescue and cisplatinum. Now, the purpose of the treatment for osteosarcoma are assurance of their life and functional and beautiful limb-sparing. Recently, preoperative chemotherapy for limb saving is given to patients with osteosarcoma of the extremities. The five year survival rate increased to 65% and limb sparing rate became above 50%. It is generally accepted that pre- and post-operative chemotherapy can inhibit pulmonary micro metastasis and prove to be of great significance in improving the survival rate of patients with osteosarcoma of extremities and achieve limb salvage operation.

Adult↗
PubMed1989

Studies on the structure of NADH: ubiquinone oxidoreductase complex: topography of the subunits of the iron-sulfur protein component.

Resolution of the mitochondrial NADH:ubiquinone oxidoreductase complex (Complex I) by chaotropic agents result in the separation of three building blocks of the enzyme, designated FP (flavoprotein), IP (iron-sulfur protein), and HP (hydrophobic protein). FP contains three subunits of Mr 51, 24, and 9 kDa; one FMN; and two iron-sulfur clusters. Immunochemical studies with monospecific antibodies to the FP subunits have indicated that all three subunits of FP protrude from the inner mitochondrial membrane on the matrix side, whereas no reactive epitopes from these subunits were found exposed on the cytosolic side [A.-L. Han, T. Yagi, and Y. Hatefi (1988) Arch. Biochem. Biophys. 267, 490-496]. IP contains six subunits of Mr 75, 49, 30, 18, 15, and 13 kDa and four iron-sulfur clusters. In the present study, immunochemical experiments (enzyme-linked immunosorbent assays and 125I-protein A labeling) were carried out with monospecific antibodies to the above IP subunits and with bovine Complex I, submitochondrial particles, mitoplasts, and intact mitochondria as sources of antigens. Results have indicated that all six IP subunits protrude from the inner mitochondrial membrane into the matrix, and that the 75-kDa subunit, and possibly the 15-kDa subunit, protrude in mitoplasts from the cytosolic side as well. No epitopes reactive toward the monospecific antibodies to the 49-, 30-, 18-, and 13-kDa subunits were detected in mitoplasts.

Animals↗
PubMed1989

EPR study of the redox interactions in cytochrome c3 from Desulfovibrio vulgaris Miyazaki.

We present a new examination of the EPR redox titration data for the tetraheme cytochrome c3 from Desulfovibrio vulgaris Miyazaki. Our analysis includes the contribution of the interaction potentials between the four redox sites and is based on the model previously developed for the study of cytochrome c3 from Desulfovibrio desulfuricans Norway. We observed, as for D. desulfuricans Norway cytochrome c3, that the conformation of the heme with the lowest redox potential, heme 4, is sensitive to the redox state of the heme with the highest potential, heme 1. However in D. vulgaris Miyazaki cytochrome c3 spectral simulations show that heme 4 is present in two conformational states which interconvert partially when heme 1 is reduced. The sets of redox parameters which satisfy the fitting procedure of the titration curves are in the following domain: -250 mV less than or equal to e41 less than or equal to -220 mV, -325 mV less than or equal to e2 less than or equal to -320 mV, -335 mV less than or equal to e3 less than or equal to -330 mV, -360 mV less than or equal to e4 less than or equal to -355 mV, -5 mV less than or equal to I12 less than or equal to 20 mV, -10 mV less than or equal to I13 less than or equal to 5 mV, -15 mV less than or equal to I23 less than or equal to -5 mV, -15 mV less than or equal to I24 less than or equal to -10 mV, -25 mV, less than or equal to I34 less than or equal to -15 mV. As in D. desulfuricans Norway cytochrome c3 the interactions are moderate. Simple electrostatic considerations suggest that these moderate values could be related to the large accessibility of the hemes to the solvent. Our work does not confirm the existence of a cooperative interaction between heme 2 and heme 3 which has been proposed on the basis of electrochemical measurements.

Binding, Competitive↗
PubMed1989

Cotransfection of plasmids with ras and myc oncogenes to diploid cells derived from rodent fetuses: alteration of neoplastic transformation frequency depending on the gestation period.

To analyze the mechanism of neoplastic transformation of rodent diploid cells by ras and myc oncogenes, human EJ c-Ha-ras and mouse c-myc second and third exons promoted by SV40 promoter were connected to pSV2neo and pSV2gpt, respectively. Mouse and rat primary fetal cells cotransfected with both genes formed transformed and nontransformed colonies in a medium containing G418 and mycophenolic acid (MPA). The proportion of transformed colonies in the total G418/MPA-resistant colonies decreased dependent on the stage of the gestation period of rat fetuses from which primary cells had been obtained. Analysis of randomly isolated colonies showed that the transformed colonies had a high copy number and high amount of expression of the introduced genes, were anchorage independent, and were tumorigenic in nude mice. On the other hand, the nontransformed colonies had a low copy number, low amount of expression, and no tumorigenicity. This contrast indicated not only that the activated Ha-ras and myc oncogenes had been integrated, but also that the amplification or overexpression (or both) of these genes was required for the rodent diploid cells to be transformed. We conclude that early-stage rat fetal cells might have endogenous factors that promote cell transformation. Alternatively, late-stage cells might have factors that suppress cell transformation by activated Ha-ras and myc oncogenes.

Animals↗
PubMed1989

1-Hydroxyethylidene-1,1-bisphosphonate (HEBP) simultaneously induces two distinct types of hypomineralization in the rat incisor dentine.

Effects of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) on the dentinogenesis of the rat maxillary incisor were microradiographically examined 96 hours after a single subcutaneous injection. HEBP produced hypomineralized incremental bands in the enamel (HPOe) and in the dentine (outer HPO1 and inner HPO2) in a dose-dependent manner. In the labial dentine, both HPO1 and HPO2 did not extend apically beyond the apical limit of the HPOe and were thus located in the circumpulpal dentine. The two lesions in the labial dentine fully developed with a dosage of 10 mg/ P/kg or larger, and with 15 mg P/kg or larger, gross hypoplastic lesions developed. Therefore, histological analysis at shorter postinjection intervals was carried out on the labial dentine with 10 mg P/kg of HEBP. The HPO1 appeared along the dentine-predentine junction by 24 hours and was characterized by reduced numbers of inorganic crystals and 10 nm particles which invested the collagen fibrils. Therefore, the HPO1 was judged to be produced by the disturbance of transformation of the predentine to dentine. The precursor lesion of HPO2 appeared in the proximal predentine by 4 hours, and was characterized by reduced number of collagen fibrils and unusually coarse interfibrillar stippled material. This lesion migrated to the dentine by 96 hours and became the HPO2, which was characterized by reduced number of collagen fibrils. Individual collagen fibrils in the HPO2 were invested by as many inorganic crystals and 10 nm particles as in the normal dentine. The HPO2 is considered to be produced by the disturbance of organic matrix formation.

Animals↗
PubMed1989

3,4-Dinitrophenyl N-acetyl-beta-D-glucosaminide, a synthetic substrate for direct spectrophotometric assay of N-acetyl-beta-D-glucosaminidase or N-acetyl-beta-D-hexosaminidase.

3,4-Dinitrophenyl N-acetyl-beta-D-glucosaminide (3,4-dnpGlcNAc) was synthesized and proposed as an artificial substrate for N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) and N-acetyl-beta-D-hexosaminidase (EC 3.2.1.52) (collectively abbreviated as NAGase). 3,4-dnpGlcNAc is water soluble and is fairly stable in aqueous medium. 3,4-Dinitrophenol released from 3,4-dnpGlcNAc by NAGase absorbs light of 400 nm at pH near 5, where the activity of urinary NAGase is assayed for diagnostic use. Direct and sensitive spectrophotometric assay of NAGase is, thus, possible using 3,4-dnpGlcNAc as an artificial substrate by monitoring the increase of A400 due to the release of 3,4-dinitrophenol in a thermostated spectrophotometer.

Acetylglucosamine↗
PubMed1989

Dynamics of signal conduction from soma to axon terminal of the teleost retinal horizontal cell: in vivo, in vitro and model studies.

A quantitative study is made on dynamic (frequency-sensitive) properties of the signal conduction between soma and axon terminal of the retinal horizontal cell. Dim flashes of same intensity produced nearly identical responses in soma and axon terminal, indicating that the voltage signal is conducted from soma to axon terminal with little attenuation or distortion. The membrane impedance of axon terminal was measured in solitary-cell preparations under voltage clamp, in order to determine parameters of a resistive-capacitive cable model for the horizontal cell. The simulation analysis shows that passive linear cable models of the present type confront inherent difficulty in predicting dynamical properties of actual flash responses of axon terminal. A nonlinear mechanism is believed to facilitate high-frequency signal conduction along the slender axon that connects soma and axon terminal.

Animals↗
PubMed1989

Intracellular predominance of the pyridoxal 5'-phosphate form of aspartate aminotransferase in Escherichia coli B and reversible transformation of this form by extracellular substances.

The intracellular proportion of the pyridoxal 5'-phosphate form of aspartate aminotransferase to the total enzyme in E. coli B cells was determined by a newly devised method, dependent on selective inactivation of the intracellular pyridoxal 5'-phosphate form of the enzyme by extracellularly added sodium borohydride. A large portion (80-99%) of the intracellular aspartate aminotransferase was in pyridoxal 5'-phosphate form in both natural and synthetic medium-grown bacterial cells. The intracellular predominancy of pyridoxal 5'-phosphate did not vary during the growth of bacteria and during incubation of bacterial cells in various kinds of buffers with different pH values. In contrast, the saturation levels generally used to describe in vivo the proportions of the apo and holo vitamin B6-dependent enzymes did not reflect the intracellular amount of the pyridoxal 5'-phosphate (holo) form of aspartate aminotransferase probably because the intracellular pyridoxal 5'-phosphate form was changed to an apo form by the disruption of bacterial cells for preparing crude extract. Various extracellularly-added vitamin B6 antagonists decreased the intracellular amount of pyridoxal 5'-phosphate without decrease in the total intracellular activity of the enzyme. The modified forms were stable in E. coli B cells and reversed into pyridoxal 5'-phosphate form by incubation of the antagonist-treated cells in the buffer containing pyridoxal. The present results showed that the sodium borohydride reduction method can be used for further analysis of the in vivo interaction of pyridoxal 5'-phosphate and apoaspartate aminotransferase. The fact that about 50% of the intracellular pyridoxal 5'-phosphate form was changed to a modified form without impairment of cell growth in the presence of 4-deoxypyridoxine, and that about 50% of intracellular modified aspartate aminotransferase was reversed to pyridoxal 5'-phosphate by the removal of antagonist followed by incubation suggested that there exists characteristically 2 different fractions of pyridoxal 5'-phosphate forms of aspartate aminotransferase in E. coli cells.

Aspartate Aminotransferases↗
PubMed1989

5-Azacytidine-induced recovery of O6-alkylguanine--DNA alkyltransferase activity in mouse Ha821 cells.

Mouse Ha821 cells, Harvey murine sarcoma virus-transformed NIH3T3 cells, have extremely low O6-alkylguanine--DNA alkyltransferase (O6AGTase) activity and are hypersensitive to an anti-tumor chloroethylating agent 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU). The treatment of Ha821 cells with a DNA demethylating agent, 5-azacytidine, resulted in an increase in the frequency of ACNU-resistant cell clones. All randomly isolated ACNU-resistant cell clones were found to have O6AGTase activity comparable to the level of the parental NIH3T3 cells. These results suggest that reversible loss of O6AGTase activity in Ha821 cells is caused at least in part by inactivation of the O6AGTase gene due to methylation of cytosine in the gene.

Animals↗
PubMed1989

Similarity in the effect of caffeine on DNA synthesis after UV irradiation between xeroderma pigmentosum variant cells and mouse cells.

The effect of UV irradiation on the rate of DNA synthesis was compared among normal human, xeroderma pigmentosum (XP, group A and variant) and mouse cells with and without caffeine in the culture medium after UV irradiation. At the same levels of survival, approximately 37%, all cells showed reduction in the rate of synthesis 0-3 h after UV irradiation followed by a recovery to normal or near-normal level 12 h later. In the presence of caffeine, no change in the recovery patterns was observed in normal human and XP A cells. XP variant cells and mouse cells showed little or no recovery in the presence of caffeine even after 12 h, when full recovery was obtained without caffeine. XP variant and mouse cells appear to have a common response in that post-irradiation treatment with caffeine inhibits reinitiation of UV-reduced DNA replication. Enhancement by caffeine of UV-killing in XP variant and mouse cells may be due to the retarded resumption of DNA replication.

Animals↗
PubMed1989

Effectiveness of insulin suppositories in diabetic patients.

Experimental insulin suppositories regulated postprandial hyperglycaemia in diabetic patients. The insulin suppositories seemed also to avoid hyperinsulinaemia. The formulation with more rapid dissolution of insulin, which contained a solid dispersed form of insulin, effectively reduced the insulin dose required.

Adult↗
PubMed1989

[Comparative evaluation of markers with reverse transcriptase inhibiting antibody in human immunodeficiency virus type 1 infection].

To investigate a non-RI test which is equivalent to the reverse transcriptase inhibiting antibody test, a reverse transcriptase inhibiting antibody was compared to the absolute number of CD-4 or CD-8 cells or CD-4/-8 ratio and also to photodensitometric analysis for western blotting. There is no correlation of the reverse transcriptase with any test for cell numbers and their ratio. In photodensitometry, relative units of anti-p65 and anti-p51 were compared with reverse transcriptase inhibiting antibody. The reverse transcriptase inhibiting antibody showed a higher correlation to the relative unit of p65 antibodies than that of p51 antibodies. The photodensitometric analysis of western blotting for a serum test may be a possible method to find a prognostic marker in HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Contralateral hearing and tympanoplasty].

The relationship between the contralateral hearing threshold in the operated ear and the type of tympanoplasty and the hearing threshold in the operated ear was investigated in this report. The subjects of analysis were 863 ears that received tympanoplasty during the past nine years at the Nippon Medical School Main Hospital. Patients who had good hearing in the contralateral ear received type I tympanoplasty more frequently than did those who had poor hearing on the contralateral ear. On the other hand, patients who had poor hearing in the contralateral ear received a modified type III tympanoplasty more frequently. Patients who had good hearing in the contralateral ear tended to have better hearing in the operated ear compared to those who had poor hearing in the contralateral ear. The hearing threshold in patients who had normal contralateral hearing on the average had 20 dB better hearing than did those who had profound hearing loss in the contralateral ear. More than one third of the patients whose hearing thresholds were worse than 30 dB in the operated ear also had a contralateral hearing loss of 30 dB or more. The decision to perform tympanoplasty in cases of the better hearing ear or the only hearing ear must be made very carefully. The contralateral hearing in patients with chronic otitis media, however, is frequently not normal as was evidenced in this investigation. Also, patients who had poor hearing or were deaf in the contralateral ear received more benefit by tympanoplasty than did those who had good hearing in the contralateral ear.(ABSTRACT TRUNCATED AT 250 WORDS)

Auditory Threshold↗
PubMed1989

Electron microscopic study of condylar cartilage of rat mandible stained with ruthenium red: proteoglycans and hypertrophic chondrocytes.

Ultrastructure of hypertrophic chondrocytes and extracellular matrix in condylar cartilage of rat mandible was studied in conjunction with ruthenium red staining. Special care was given to the preservation of proteoglycans in the extracellular matrix. Ruthenium red-positive granules were observed in the pericellular matrix of condylar chondrocytes, and their size and number increased around the hypertrophic cells. However, these granules disappeared in the lowest hypertrophic zone, in which uncalcified cartilage matrix was also disintegrated prior to initiation of ossification. Moreover, hypertrophic chondrocytes observed at the lowest zone appeared intact in their ultrastructural features, i.e., containing numbers of lysosomes and coated vesicles in the cytoplasm facing the blood capillaries. The results strongly suggest that the lowest hypertrophic chondrocytes in rat condylar cartilage may have an active role in the degradation and resorption of the pericellular matrix, especially proteoglycans, and uncalcified matrix, which changes seem an essential step for the initiation of endochondral ossification.

Animals↗