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Biomedical subjects

M Taira

Publications and source records attributed to M Taira.

233 records · Page 13Linked to original sources
PubMed1982

Nucleotide sequence and evolution of the rat mitochondrial cytochrome b gene containing the ochre termination codon.

The nucleotide sequences of the genes for cytochrome b and three potential transfer RNAs (tRNAPro, tRNAThr and tRNAGlu) in cloned rat mitochondrial DNA were determined. The derived amino acid sequence of the cytochrome b protein from the light strand indicated that the C-terminal amino acid is asparagine and the ochre termination codon is encoded in the DNA, in contrast to the the lack of termination codon in the reading frame of human [Anderson et al., Nature 290 (1981) 457] or mouse [Bibb et al., Cell 26 (1981) 167] mitochondrial DNA. The first ATG codon of the cytochrome b gene was spaced five nucleotides from the 5'-end of the tRNAGlu gene on the heavy strand. There was a single nucleotide spacing between the termination codon of the cytochrome b gene and the 5' end of the tRNAThr gene in the light strand. There was also a single nucleotide spacing between the 3'-end of the tRNAThr gene and the 3'-end of the tRNAPro gene on the heavy strand. The amino acid and nucleotide sequences of the cytochrome b genes of mammals and yeast [Nobrega and Tzagoloff, J. Biol. Chem. 255 (1980) 9828] were compared to reveal structural differences in two very different species. At the same time, amino acid substitutions in particular regions of the mammalian gene corresponding to the exon-intron boundaries in the yeast gene were noted. These genetic features are discussed in relation to the extreme compression of genetic information in the mammalian mitochondrial genome as related to the evolution of the gene organization and its sequence.

Amino Acid Sequence↗
PubMed1981

Effects of deoxyribonuclease I and micrococcal nuclease on the release of dexamethasone-receptor complex from nuclei of sensitive and insensitive hepatoma cell lines.

(1) Fu5 cells were sensitive to the glucocorticoid inhibition of cell growth and the hormonal induction of tyrosine aminotransferase (but not fructose-1,6-bisphosphatase and glycogen synthase). AH-130 and AH-7974 cells were insensitive to both effects. (2) The release of [3H]dexamethasone radioactivity from the nuclei of Fu5 and AH-130 cells preincubated with [3H]dexamethasone increased as the KCl concentration increased from 0 to 0.4 M, with no significant difference between the two cell lines. (3) The radioactivity was more sensitively released in Fu5 nuclei than in AH-130 nuclei upon treatment with DNAase I. The release of radioactivity was always larger than the release of DNA in both cell nuclei. In contrast to DNAase I, micrococcal nuclease treatment did not show any difference between the two cell lines in the release of radioactivity from nuclei, always showing a release of radioactivity equal to that of DNA.

Animals↗
PubMedDate not supplied

Differences in solubility of two types of heterogeneous fluoridated hydroxyapatites.

Two types of heterogeneous fluoridated apatites, H-F and F-H, were synthesized by supplying fluoride over the whole range of the degree of fluoridation (X = 0-1.0) during the initial or final half of the experimental period. Although X-ray diffraction patterns and scanning electron microscopy (SEM) photographs of both H-F and F-H type apatites were not significantly different, high-resolution transmission electron microscopy (HR-TEM) showed quite different features; H-F type apatites were elongated hexagons with electron beam damage in the core, while F-H type apatites were rather wider hexagons and approached the typical hexagon of fluorapatite. These results supported the previous speculations on the two different types of heterogeneous fluoridated hydroxyapatites synthesized with fluoride concentration stoichiometrically equivalent to that of fluorapatite: hydroxyapatite covered with fluorapatite and fluorapatite covered with hydroxyapatite. The apparent solubility of H-F type apatites decreased with increases in degree of fluoridation, while that of F-H type apatites decreased markedly and then remained almost constant.

Apatites↗
PubMedDate not supplied

Acute mesenteric ischemia. CT and plain radiographic analysis of 26 cases.

The purpose of this study was to assess the computed tomography (CT) and plain radiographic findings of acute mesenteric ischemia, in an effort to elucidate its poor prognostic signs. The study group consisted of 26 cases with pathologically or angiographically proven mesenteric ischemia. The pathologically proven longitudinal extent of the bowel ischemia was graded using six degrees, and correlated with the radiographic findings. The mortality of the patients depended primarily on the extent of infarctions and the age of the patient. Patients with bowel dilation or abnormal gas in the bowel wall or portal system were prone to have wider extents of ischemia.

Acute Disease↗
PubMedDate not supplied

Random number generation evaluation in patients with systemic lupus erythematosus indicates a heterogeneous nature of central nervous system vulnerability.

OBJECTIVE: To evaluate the vulnerability of the central nervous system (CNS) in patients with systemic lupus erythematosus (SLE). METHODS: Forty-eight patients with SLE, 58 with schizophrenia in remission and 39 healthy controls were enrolled in the study. Patients vocally generated 100 numbers in a random fashion, using numbers 0 to 9, and were evaluated with seriality scores. Patients with SLE were subgrouped according to differences in the presence of Raynaud's phenomenon, anti-phospholipid antibody, lupus activity, and a history of neuropsychiatric (NP) lupus, and these patients were also evaluated by comparison with their counterparts. RESULTS: In general, patients with SLE showed lower seriality scores than patients with schizophrenia, and higher seriality scores than normal controls. The scores of the patients with a history of NP lupus matched those with schizophrenia, and the scores of never having NP lupus matched those of the healthy controls. CONCLUSIONS: CNS vulnerability may be prolonged in patients who have a history of NP lupus even when they appear to be in normal NP status. The damage in random number generation (RNG) observed in patients with a history of NP lupus seemed equal to that found in those with schizophrenia, whereas those patients never having NP lupus appeared to be equal to the controls. The current study suggests a heterogeneous nature of SLE and prolonged damage, especially in CNS vulnerability, when evaluating with RNG.

Adult↗
PubMedDate not supplied

Neural mechanisms of visual guidance of hand action in the parietal cortex of the monkey.

We studied the functional properties of the hand manipulation task-related neurons (N = 136) in the posterior bank of the intraparietal sulcus (IPS) using four kinds of objects for manipulation. We performed cluster analysis by comparing the profiles of activity of these neurons across objects during manipulation in the light, and classified them into nine groups, four highly selective, four moderately selective, and one nonselective group. Activity profiles of these neurons across objects were analyzed in four task conditions: object manipulation and object fixation both in the light and in the dark. Cells were classified as "motor-dominant," "visual-dominant," and "visual and motor" neurons, and the latter two were further subdivided into object type and non-object type. Most of the highly selective neurons (35 of 136) preferred the same object for manipulation in the dark as in the light. The object type "visual and motor" neurons preferred the same object for manipulation and fixation, suggesting that these neurons play an important role in matching the pattern of hand movement to the visuo-spatial characteristics of the object to be manipulated. A large majority of highly selective hand manipulation neurons were localized in the rostral part of the posterior bank of IPS, which we designated as the anterior intraparietal (AIP) area. We propose a conceptual model of the system for visual guidance of hand action including parietal hand manipulation neurons.

Animals↗
PubMedDate not supplied

Inhibiting action of carbohydrates on the growth of fluorapatite crystals.

Hydroxyapatite (HAp) and fluorapatite (FAp) were synthesized in the presence of carbohydrates (glucose, fructose, galactose and sucrose). X-ray diffraction analysis showed that the crystallinity of two FAp groups that were synthesized in the presence of glucose or sucrose decreased with the increase in carbohydrate content. In SEM photographs we found that the size of their crystals was small and the shape changed. However, FAp groups that were snythesized in the presence of fructose or galactose showed little change in their crystallinity and shape. Four carbohydrates had some influence on size, but not on shape or crystallinity when synthesizing HAp. These results suggest that glucose and/or sucrose has a chemical affinity to FAp and inhibits the growth of FAp crystals.

Analysis of Variance↗
PubMedDate not supplied

Cytotoxic effect of methyl methacrylate on 4 cultured fibroblasts.

PURPOSE: The objective of this study was to examine the cytotoxic effect of methyl methacrylate (MMA) monomer on 4 mammalian fibroblasts. MATERIALS AND METHODS: Four cells--C3H10T1/2, L929, Balb/3T3 clone A31, and MC3T3-E1--were incubated for 6 days in 24-well microplates filled with 1 mL of Dulbecco's Modified Eagle medium containing MMA monomer that ranged from 0 to 200 mM/L. Cytotoxicity was evaluated by direct cell number count. RESULTS: L929 possessed the largest TC50 value (the amount of MMA that caused 50% cell death) (34 mM/L), and Balb/3T3 clone A31 had the least value (1 mM/L); C3H10T1/2 and MC3T3-E1 had intermediate values (25 mM/L and 16 mM/L, respectively). CONCLUSION: This study showed that the MMA monomer had dose-dependent cytotoxicity, which varied among the cells tested.

3T3 Cells↗