[Malignant schwannoma of the mandibular bone: report of a case].
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Aged↗
Biomedical subjects
T Yagi
Publications and source records attributed to T Yagi.
[Clinical results of osteochondral allografts in the treatment of osteochondral defects].
There have been very few clinical reports on osteochondral allograft in Japan. In the allograft we did for osteochondral defects of the knee, seven fresh grafts and four frozen grafts were used. In six of the seven fresh grafts, the surface presented macroscopically and/or arthroscopically the appearance of almost complete normality. From the histological study of the cartilage for biopsy which was obtained from the fresh graft at postoperative fifteen months, the cell viability, though decreased in the superficial layer, was fairly normal and profusely produced proteoglycan stained with safranin-O in both the middle and the deep layers. The cell viability, however, was decreased remarkably or disappeared in all three layers in the biopsy cartilage taken from the frozen graft at over one year postoperatively. The eight of the eleven knees treated with the osteochondral allograft have preserved the joint space on one foot standing radiogram and revealed good function clinically.
Adolescent↗
Spectral and kinetic abnormality during the reduction of cytochrome c3 catalyzed by hydrogenase with hydrogen.
Reduction process of cytochrome c3 by hydrogenase (EC 1.12.2.1) under H2 was analyzed by means of spectrophotometry. When cytochrome c3 is in equilibrium with H2 under reduced pressure, spectral abnormality in the Soret region appeared most significantly in 1/4 reduction state, less significantly at 1/2 reduction state, and disappeared at 3/4 reduction state. The spectral changes during the enzymic reduction of cytochrome c3 in H2-saturated solution traced at several wavelengths also showed spectral abnormality in the Soret region at the early stage of reaction. The first-order rate constants for the successive reduction steps from all-ferric to all-ferrous form of cytochrome c3 was estimated to be k1 = 0.061 s-1, k2 = 0.063 s-1, k3 = 0.039 s-1 and k4 = 0.014 s-1 (cytochrome c3: 2 microM; hydrogenase: 2 nM, and at 20 degrees C, pH 7.0). Strong interaction is suggested between hemes 3 and 4 (for the refined structure and heme-numbering, see Higuchi, Y., Kusunoki, M., Matsuura, Y., Yasuoka, N. and Kakudo, M. (1984) J. Mol. Biol. 172, 109-139). The first electron from hydrogenase is supposed to be transferred to these hemes and delocalized between them, and the second electron, among hemes 3, 4 and 1. The characteristic behavior in the enzymic reduction of cytochrome c3 is different from that in non-enzymic reduction.
Cytochrome c Group↗
Inactivation of the Pseudomonas striata broad specificity amino acid racemase by D and L isomers of beta-substituted alanines: kinetics, stoichiometry, active site peptide, and mechanistic studies.
Mechanism-based inactivators were used to probe the active site of the broad specificity amino acid racemase from Pseudomonas striata. Kinetic parameters for the inactivation of the racemase with both stereoisomers of beta-fluoroalanine, beta-chloroalanine, and O-acetylserine were determined. By use of 14C-labeled O-acetylserines, the stoichiometry of inactivator binding was found to be one inactivator bound per enzyme subunit. The PLP-dependent enzyme contains one coenzyme per subunit, and after NaB3H4 reduction of the PLP-imine bond, followed by trypsin digestion of the protein, the amino acid sequence of the PLP-binding peptide was determined. Trypsin digestion of the enzyme labeled with either L or D isomer of O-acetylserine and sequencing of the labeled peptide revealed that the inactivators bind to the same lysine residue which binds PLP in native enzyme. The characterization of a PLP adduct released from inactivated enzyme under some conditions is also described. Implications of the formation of this compound with respect to the overall reaction mechanism of inactivation are discussed.
Alanine↗
The complete amino acid sequence of aspartate aminotransferase from Escherichia coli: sequence comparison with pig isoenzymes.
The amino acid sequence of aspartate aminotransferase from E. coli B was determined by the alignment of seven cyanogen bromide peptides. The established sequence of the subunit was composed of 396 amino acid residues, and the molecular weight was calculated to be 43,573. The sequence was compared with those of the pig cytoplasmic and mitochondrial isoenzymes, showing that nearly 30% of all residues were invariant and that the E. coli enzyme exhibited the same degree of homology (about 40%) with either of them. Although majority of the residues were substituted, the functional residues constituting the active site structure were conserved.
Amino Acid Sequence↗
Thiols in oxidative phosphorylation: inhibition and energy-potentiated uncoupling by monothiol and dithiol modifiers.
Three apparently different modifications of submitochondrial particles (SMP) or ATP synthase preparations (complex V) inhibit oxidative phosphorylation and ATP-32Pi exchange activities, all of which are reversible by addition of mono- or dithiols. (a) Triphenyltin chloride inhibits ATP synthesis and hydrolysis without uncoupling. The inhibition by triphenyltin chloride is reversible by addition of beta-mercaptoethanol, dithiothreitol, or dihydrolipoamide. (b) Factor B is a water-soluble protein of Mr (11-12) X 10(3), contains a vicinal dithiol, and is required for energy transfer to and from F1-ATPase when tested with SMP-rendered factor B deficient by extraction with ammonia-ethylenediaminetetraacetic acid (EDTA) (AE-SMP). Treatment of factor B with mono- and dithiol modifiers, such as p-(chloromercuri)benzenesulfonate (PCMPS), Cd2+, or diazenedicarboxylic acid bis(dimethylamide) (diamide), inhibits factor B. This inhibition is reversed by addition to modified factor B of appropriate mono- and dithiol compounds. Preparations of AE-SMP are partially F1 deficient and partially uncoupled. The uncoupling can be repaired completely by addition of factor B or low levels of oligomycin, or to a large extent by addition of F1-ATPase + oligomycin sensitivity conferring protein. (c) SMP, AE-SMP, and complex V can be completely uncoupled by treatment at 30 degrees C with phenylarsine oxide, Cd2+, diamide, PCMPS, monobromobimane, and mono- and bifunctional maleimides. The uncoupling by these reagents is potentiated by membrane energization. Uncoupling by diamide is greater than or equal to 80% reversed by dihydrolipoamide or beta-mercaptoethanol, the former being much more potent. Dithiothreitol and dithioerythritol are poorly effective.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Modulation of the kinetics and the steady-state level of intermediates of mitochondrial coupled reactions by inhibitors and uncouplers.
In oxidative phosphorylation and ATP-driven uphill electron transfer from succinate to NAD, double-reciprocal plots of rates vs. substrate concentrations of the energy-driven reactions are a family of parallel lines at several fixed subsaturating concentrations of the substrates or at several moderate concentrations of the inhibitors of the energy-yielding reactions. Thus, as shown elsewhere [Hatefi, Y., Yagi, T., Phelps, D. C., Wong, S.-Y., Vik, S. B., & Galante, Y. M. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 1756-1760], partial uncoupling decreases the Vappmax and increases the Kappm of the substrates of the energy-driven reactions, resulting in a decrease of Vmax/Km as a function of increased uncoupling. However, partial limitation of the flow rates of the energy-yielding reactions decreases both the Vappmax and the Kappm of the substrates of the energy-driven reactions, resulting in no change in Vmax/Km. This is true as long as the rate limitation is moderate (e.g., less than 60%), under which conditions the steady-state membrane potential (delta psi) remains essentially unchanged. At high inhibition of the energy-yielding reactions, or at moderate inhibition in the presence of low levels of an uncoupler to cause partial uncoupling, then the family of double-reciprocal plots is no longer parallel and tends to converge toward the left. Under these conditions, steady-state delta psi and Vmax/Km also decrease as inhibition is increased. The relationship between the magnitude of steady-state delta psi and the rate of the energy-driven reaction was studied in oxidative phosphorylation, ATP-driven electron transfer from succinate to NAD, and respiration-driven uniport calcium transport by intact mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)
Adenosine Triphosphate↗
On the mechanism of H+ translocation by mitochondrial H+ -ATPase. Studies with chemical modifier of tyrosine residues.
In this paper a detailed study of the effect of nitration of tyrosine residues by tetranitromethane on H+ conduction and other reactions catalyzed by the H+ -ATPase complex in phosphorylating submitochondrial particles, uncoupled particles, and the purified complex is presented. Tetranitromethane treatment of submitochondrial particles results in marked inhibition of ATP hydrolysis, ATP-33Pi exchange, and proton conduction by the H+ -ATPase complex. These effects are caused by nitration of tyrosine residues of H+ -ATPase complex as shown by the appearance of the absorption peak at 360 nm (specific for nitrotyrosine formation) and inhibition of ATP hydrolysis and ATP-33Pi exchange in the complex purified from tetranitromethane-treated particles. H+ conduction in phospholipid vesicles inlaid with F0 is also inhibited by tetranitromethane treatment. These observations indicate that tyrosine residue(s) of F0 are critically involved in energy-linked proton translocation in the ATP-ase complex.
Adenosine Triphosphate↗
Neural correlates of compensation after hemilabyrinthectomy.
Vestibular brain stem neurons responsive to angular acceleration in the plane of the horizontal canal were examined in cats 30 to 52 days after contralateral labyrinthectomy and compared with similar units in cats with intact labyrinths and in other cats immediately after transection of the contralateral eighth nerve. In the compensated state, the mean spontaneous firing rate of type I neurons was 24 spikes/s, in contrast to the mean of 45/s observed immediately after contralateral labyrinthectomy. In intact cats, mean firing rate was 19 spikes/s. Sensitivity, as measured in spikes/s/deg/s2, was significantly lower immediately after labyrinthectomy than in intact controls and remained so in compensated cats. On the other hand, time constants and the ratio of adapting:nonadapting units was unchanged. Ablation of the midline cerebellum including vermis and fastigial nuclei did not materially affect these results. We concluded that (i) the main defects in static posture and nystagmus in the uncompensated state were due to the striking difference in resting firing rates between the ipsi- and contralateral vestibular nuclei; (ii) compensation in the static posture was the result of a tendency to equalize the resting firing rates in the two vestibular nuclei; and (iii) recovery in the dynamic, head-turning situation was due to partial recovery of sensitivity on the ipsilateral side, bringing it to the relatively constant, unchanging depressed sensitivity on the contralateral side.
Acceleration↗
Comparison of repair of O6-methylguanine produced by N-methyl-N'-nitro-N-nitrosoguanidine in mouse and human cells.
The repair of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-produced O6-methylguanine (O6-MeG) in DNA and its correlation with MNNG-produced cell-killing and sister chromatid exchange (SCE) induction were compared in mouse and reference human tumor cell strains. As a result, mouse cell strains were divided into three groups: (i) cells proficient in O6-MeG-repair and insensitive to MNNG similar to human Mer+ Rem+ strains; (ii) cells deficient in O6-MeG-removal and sensitive to MNNG similar to human Mer-Rem- strains; (iii) cells deficient in O6-MeG-removal but insensitive to MNNG similar to some SV40-transformed human strains. Attempts at correlating lack of capacity for O6-MeG-removal, MNNG-sensitivity and high SCE induction showed that O6-MeG in DNA may be a lesion common to cell-killing and SCE induction only in mouse cells of groups i and ii. Levels of O6-MeG-DNA methyltransferase activity in mouse cells were measured and the enzyme had the same molecular weight as that in human cells.
Animals↗
High-resolution electron microscopy of hydroxyapatite grown in dilute solutions.
High-resolution electron microscopy (HREM) was applied to the study of seeded crystal growth of hydroxyapatite (HA) in supersaturated solutions. The HA seed crystals were rod-shaped, elongated along the c-axis, and showed smooth contours. The seed crystals exhibited hexagonal prism facets, and one end was rhombohedrally terminated, whereas the opposite end was blunt. Growth experiments were carried out at 37 degrees C, and solution compositions were carefully selected to avoid the involvement of precursor phases during the HA growth. After five-hour growth, the total amount of precipitation was from 3 to 7% of the initial crystal mass added to the solutions; examination of the crystals by HREM disclosed the formation of projections on the end surfaces of the HA crystals. High-resolution TEM clearly showed lattice fringes with predictable spacings over the entire crystal specimen, including the formed projections. Analysis of selected regions by optical diffraction of the HRTEM fringe negatives showed that the nature and orientation of the projections were similar to those of the underlying seed crystal. High-resolution SEM of the HA crystal after five-hour growth disclosed step-like structures on the prism faces, as well as the projections localized on the ends. These results strongly suggest that more than one growth process may be involved, perhaps related to the distinct faces of the HA seed crystals.
Chemical Precipitation↗
Brainstem changes in vestibular compensation.
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Animals↗
[Mean platelet volume, platelet count and platelet retention rate in cerebral vascular disease and Alzheimer type dementia].
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Aged↗
Aspartate aminotransferase from E. coli--a comparative study among E. coli, and yeast enzymes and pig heart isozymes.
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Amino Acid Sequence↗
[Correlation between EEG and auditory brainstem response (ABR) in comatose patients--diagnosis of brain death by ABR].
ABRs and EEGs were recorded from fifty comatose patients. Among them 21 patients were in deep coma and remaining 29 were in brain death that was diagnosed from clinical criteria. All the patients who showed some activity in EEG had ABR which showed waves I through V. However, there was no correlation between grade of EEG classification, dominant alpha, theta, or delta rhythm, and the inter wave latencies between waves I through V in the ABRs. Eleven of the twenty-nine patients who were diagnosed as brain death from clinical criteria and isoelectric EEG showed waves I through V potentials in ABR. Eight of these eleven patients even exhibited normal or nearly normal ABRs which had I to V latencies less than 4.4 ms. However, all the patients who showed isoelectric EEG and no response ABR died. Thus it is concluded that the ABR should be included for identification of brain death in addition to the clinical examination and EEG recordings.
Brain Death↗
[A study on torsion of the lower leg in osteoarthritis of the knee. Measurement of leg torsion by computerized tomography].
UNLABELLED: Lower leg torsion was measured by computerized tomography (CT-scan) in the knees with osteoarthritis. MATERIALS AND METHODS: Experimental studies; Using the Toshiba CT/TCT-60A, the degree of torsion in five dried tibias were measured in three positions of varus, 0 degrees, 10 degrees and 20 degrees; and in two positions of flexion 0 degrees and 20 degrees. Clinical studies; The degree of tibial torsion was measured by CT-scan in 68 adult patients (85 knees) and compared with the torsion in 13 controls (24 tibias). The correlation between tibial torsion and osteoporosity was investigated by measuring CT-density of the third lumbar vertebra. RESULTS: No statistically significant difference was found among the results of measurement obtained in five dried tibias placed in three positions of varus and in two positions of flexion. These results indicate that measurement of torsion using CT-scan is not influenced by the position when varus and flexion deformity are less than 20 degrees. Osteoarthritic knees were divided into five radiographic stages. There were significant differences between the lateral tibial torsions for each stage. The lateral tibial torsion was 23.5 degrees in normal adults, 14.1 degrees in stage II, 11.9 degrees in stage III, 7.5 degrees in stage IV and V, for an average of 11.3 degrees. The rate of decrease in lateral tibial torsion was 59.6% in the proximal tibia, 4.2% in the tibial shaft and 36.2% in the distal tibia. The decreases of lateral tibial torsion were correlated with decrease of CT-density of the third lumbar vertebra. CONCLUSION: It is apparent from this study that there is a correlation between decreasing lateral tibial torsion with the radiographic stage of osteoarthritis of the knee and general osteoporosity.
Adult↗
Effects of iodine and thyroid hormone in ameliorating rickets on Steenbock diet.
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Animals↗
[A histological study on osteosarcoma. Part I: Relationship between modes of osteoid formation and differentiation of tumor cells].
This study was undertaken to clarify whether the osteoid forming activity seen in osteosarcoma can be used as an index to show the degree of differentiation of the tumor. Twenty six human osteosarcomas which had been amputated in our clinics were used in this study. The whole slice of the primary tumor was stained by HE and Masson stain. The following observations were microscopically made in the peripheral, transitional and central part of the tumor; 1) the content and maturity of osteoid, 2) the degree of polymorphism and mitotic activity of the tumor cells. In 13 out of 26 cases, the amount and maturity of osteoid gradually increased toward the center of the tumor. On the other hand, the degree of polymorphism and mitotic activity of tumor cells in these cases gradually decreased toward the center. Mitotic activity in the center of the tumor decreased to about half of the peripheral part. The clinical courses of these 13 cases were milder than those in which the gradual increase of the amount and maturity of osteoid toward the center of the tumor were not observed. These results showed that zone formation of osteoid maturity in osteosarcoma can be used as an index to show the degree of differentiation of the tumor.
Adolescent↗