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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 235 records · Page 13Linked to original sources
PubMed1996

Transient ischemia depletes free ubiquitin in the gerbil hippocampal CA1 neurons.

We investigated ubiquitin immunoreactivity in the post-ischemic gerbil hippocampus using a panel of ubiquitin antibodies. Immunostaining for ubiquitin in the hippocampus was strongly dependent on the antibodies used. With rabbit polyclonal antibody U-5379, immunoreactivity disappeared from the hippocampus in the early reperfusion period and reappeared in the dentate granule cells and CA3 pyramidal cells but never in the CA1 pyramidal cells. In contrast, rat monoclonal antibody DF2 and mouse monoclonal antibody MAB1510 showed sustained immunoreactivity in the CA1 during the 48-hour reperfusion period. On the immunoblots of gerbil brain homogenates, three antibodies, U-5379, DF2 and MAB1510, exhibited similar specificities; all three labeled free ubiquitin most strongly. Immunoprecipitation disclosed that, under nondenaturing conditions, U-5379 bound exclusively free ubiquitin, whereas DF2 and MAB1510 had little affinity for free ubiquitin but appeared to have more affinity for conjugated ubiquitin. Immunoabsorption of these antibodies with free ubiquitin confirmed the above result. It is most likely that U-5379 recognized free ubiquitin in the tissue, whereas DF2 and MAB1510 recognized preferentially conjugated ubiquitin. Thus, transient ischemia depletes free ubiquitin but not conjugated ubiquitin in the CA1. This depletion may be caused by impaired conversion from conjugated to free ubiquitin and/or failure of de novo ubiquitin synthesis.

Animals↗
PubMed1996

[Projection of epicardial U-wave change to surface precordial electrocardiogram in coronary artery disease].

U-wave changes on the intracoronary electrocardiogram (ECG) during anterior or inferoposterior myocardial ischemia were correlated with the U-wave changes in the precordial leads of the body surface ECG in 28 patients who underwent coronary angioplasty of the left anterior descending (LAD group; 17 patients) or left circumflex (LC group; 11 patients) coronary artery. The intracoronary ECG was recorded simultaneously with the body surface multiple precordial leads at the baseline and during angioplasty. The amplitude of the U-wave on the intracoronary ECG was measured quantitatively, and U-wave changes from baseline to angioplasty were assessed qualitatively on the body surface ECG. Three different patterns of U-wave changes were distinguishable on the intracoronary ECG from baseline to angioplasty: change to positivity; no change; and change to negativity. The incidence of each pattern was similar in the LAD and LC groups (35 vs 36%; 30 vs 18%; 35 vs 46%, respectively). The intracoronary ECG was more sensitive for detecting U-wave changes during angioplasty than body surface precordial ECG (LAD group 71 vs 47%; LC group 82 vs 27%). When compared to the intracoronary ECG, concordant U-wave changes occurred in the surface precordial ECG in 67% (8/12) of the LAD group with accompanying epicardial U-wave changes, and discordant changes in 33% (3/9) of the LC group with epicardial U-wave changes. The present study provides fundamental information for understanding the correlation of U-wave changes between epicardial and surface precordial ECGs during myocardial ischemia in humans. As well as primary U-wave changes in anterior myocardial ischemia, reciprocal U-wave changes may also be prominent in the surface precordial ECGs in some cases of posterior myocardial ischemia.

Adult↗
PubMed1996

Membranocystic changes in the panniculitis of dermatomyositis.

Clinically apparent panniculitis is rare in dermatomyositis. The common histopathological findings are infiltration of lymphocytes, epithelioid cells and plasma cells in the fat lobules, along with varying degrees of fat degeneration and fibrosis. We report a 65-year-old woman with dermatomyositis who developed panniculitis with a characteristic histological change known as a membranocystic lesion. Although this change has been observed in various diseases affecting the subcutaneous fat tissue, it has rarely been reported in dermatomyositis. Dermatomyositis should be included in the diseases showing a membranocystic lesion.

Aged↗
PubMed1996

Flow cytometric DNA content analysis on squamous cell carcinomas according to the preceding lesions.

DNA-ploidy in primary cutaneous squamous cell carcinomas which had developed from different preceding clinical lesions was examined by flow cytometry using paraffin-embedded blocks. DNA-aneuploidy was detected in none of 15 squamous cell carcinomas arising from a burn scar. On the other hand, 12 of 26 squamous cell carcinomas arising from sun-damaged skin in the elderly, and two of four arising from chronic radiodermatitis, showed aneuploid patterns. A significantly higher incidence of DNA-aneuploidy was observed in squamous cell carcinomas arising from sun-damaged skin than those from a burn scar (P < 0.01); the mean diameter size of the former was significantly smaller than that of the latter (P < 0.0001). The mean age of patients with aneuploid tumours (74.2 +/- 9.2: years +/- standard deviation (SD)) was significantly higher than that with diploid tumours (64.1 +/- 13.8) (P < 0.01).

Aged↗
PubMed1996

[Forensic application of two short tandem repeat (STR) polymorphic markers, FES and HUMTH01].

This paper reports polymorphisms of two short tandem repeats (STR) in the human c-fes/proto-oncogene (FES) and the human tyrosine hydroxylase gene (HUMTH01), and their application to paternity cases. Genomic DNA samples from 213 unrelated Japanese individuals and from 30 paternity cases were subjected to the polymerase chain reaction (PCR) and then the amplified products were electrophoresed in denaturing polyacrylamide sequencing gels. Allelic bands were detected with autoradiography. Seven alleles differing in the numbers of the repeat units were observed at both loci. Heterozygosity (%) and polymorphism information context were calculated, being 69% and 0.641 FES, and 70% and 0.647 for HUMTH01. The allele frequencies of the two STRs in this study were found to be similar to those previously reported on Asians but different from those in Caucasians and Blacks. When the STRs were applied to 30 paternity cases that had been already tested by using conventional markers, there were no discrepancies between the results of the STRs and of conventional markers. Furthermore, the two STRs could be successfully coamplified in multiplex PCR. These results suggest that the two STRs are useful in forensic work in Japan.

Alleles↗
PubMed1996

A study on simplification of the Standard Language Test of Aphasia (SLTA).

The Standard Language Test of Aphasia (STLA) was developed for classification and evaluation of severity of aphasia of Japanese speakers in 1975. Now it has become the most reliable test for patient with aphasic condition in Japan. However, the test involves many tasks and assessment is rather complicated. A simplified display of aphasic conditions was created by means of statistical analysis of the features of types of aphasia in order to reduce time and labor involved in SLTA for bed side use. Data were collected from 198 patients, including 40 patients with Broca aphasia (17 severe and 23 moderate cases), 64 patients with Wernicke aphasia (28 severe and 36 moderate cases) and 94 patients with global aphasia (68 severe and 26 moderate cases). A test with simplfied aphasia pattern involved naming objects for daily use (represented by pictures), pronunciation of words written in Kanji (Chinese characters) and in Kana (syllabary), pronunciation of single Kana, dictation of single Kana (oral presentation), repeating simple words presented by the examiner, dictation of words to be written in Kanji (oral presentation), matching words in Kana and a picture (pointing), writing words in Kanji (represented by pictures), writing words in Kana (represented by pictures), and auditory comprehension of words.

Adult↗
PubMed1996

Assessment and comparison of algorithms for in vivo ESR-CT imaging of bioradicals with L-band microwaves.

In ESR-CT imaging, it is much more difficult to obtain satisfactory images than in imaging with other modalities, since two inverse problems, i.e. deconvolution of observed data and reconstruction from projections, must be solved. In this work, suitable algorithms for ESR-CT are examined using simulations and experiments. The algorithms were applied to actual data from a rat's head and a satisfactory reconstructed image was obtained from the viewpoint of morphological imaging. Several properties of the algorithms are discussed: (1) which combination of deconvolution and reconstruction method is favorable, (2) whether or not a raw differential signal should be integrated before deconvolution and reconstruction procedures, and (3) how SIRT, which offers good performance in ESR-CT, depends on an initial value and a noise type.

Algorithms↗
PubMed1996

[Proton magnetic resonance spectroscopy of excised pig liver].

After evaluating ex vivo pig liver by 1H magnetic resonance spectroscopy (1H-MRS) using a 1.5 Tesla super-conducting unit, the assignment of peaks was reevaluated in vitro using a 9.4 Tesla superconducting unit. The portal vein was cannulated and perfused by cooled Euro-Collins solution, and pig liver was removed and preserved in the solution. Five to 8 g of the liver was excised before and after preservation, then extracted by perchloric acid (PCA). In 1H-MRS of PCA extracted pig liver, large peaks of fatty acid disappeared, while peaks of the choline group from 3.2-3.3 ppm were clearly observed. Using high performance liquid chromatography (HPLC) and 31P (phosphorus)-MRS, the 3.23 ppm peak was determined as glycerophosphorylcholine (GPC), which diminished after preservation. The chronological change of GPC in PCA extracted pig liver was able to be observed by 1H-MRS. GPC peak may play a role as an indicator in evaluating preserved liver by 1H-MRS.

Animals↗
PubMed1995

Short external loops as potential substrate binding site of gamma-aminobutyric acid transporters.

While the gamma-aminobutyric acid (GABA) transporter GAT1 exclusively transports GABA, GAT2, -3, and -4 also transport beta-alanine. Cross-mutations in the external loops IV, V, and VI among the various GABA transporters were performed by site-directed mutagenesis. The affinity of GABA transport as well as inhibitor sensitivity of the modified transporters was analyzed. Kinetic analysis revealed that a cross-mutation in which loop IV of GAT1 was modified to resemble GAT4 resulted in increased affinity to GABA from Km = 8.7 to 2.0 microM without changing the Vmax. A cross-mutation in loop VI, which swapped the amino acid sequence of GAT2 for GAT1, decreased the affinity to GABA (Km, 35 microM). These results suggest that loops IV and VI contribute to the binding affinity of GABA transporters. A substitution of three amino acids in loop V of GAT1 by the corresponding sequence of GAT3 resulted in beta-alanine sensitivity of its GABA uptake activity. These three amino acids in loop V seem to participate in the beta-alanine binding domain of GAT3. It is suggested that those three external loops (IV, V, and VI) form a pocket in which the substrate binds to the GABA transporters.

Amino Acid Sequence↗
PubMed1995

Secretion of laminin alpha 2 chain in cerebrospinal fluid.

The absence of laminin alpha 2 chain causes muscle cell degeneration and peripheral dysmyelination in congenital muscular dystrophy patients and dy mice, suggesting its role in the maintenance of sarcolemmal architecture and peripheral myelinogenesis. Here we demonstrate the secretion of laminin alpha 2 chain in cerebrospinal fluid (CSF). Laminin alpha 2 chain was detected as a minor component of the total CSF proteins or glycoproteins. Laminin alpha 2 chain was localized in the cytoplasm of epithelial cells of choroid plexus, suggesting active secretion. Our results suggest that immunochemical analysis of CSF laminin alpha 2 chain could be useful as an aid for the diagnosis of congenital muscular dystrophy.

Animals↗
PubMed1995

Amantadine induces c-fos in rat striatum: reversal with dopamine D1 and NMDA receptor antagonists.

Amantadine (1-aminoadamantane) induced Fos expression in the central, dorsal-medial and ventral-medial part of the striatum. The distribution pattern of Fos induced by amantadine was more similar to those seen with dopaminomimetics than with N-methyl-D-aspartate (NMDA) receptor antagonists. Pretreatment with the dopamine D1 receptor antagonist, SCH23390, and the NMDA receptor antagonist, MK-801, blocked amantadine induction of Fos in the striatum. However, amantadine induction of Fos in the striatum was unaffected by the dopamine D2 receptor antagonist, sulpiride. These results suggest that amantadine induction of Fos in the rat striatum is related to dopamine D1 and NMDA receptors.

Amantadine↗
PubMed1995

Emergent coronary angiographic findings of patients with ST depression in the inferior or lateral leads, or both, during anterior wall acute myocardial infarction.

In conclusion, the present study indicates that there are several distinctive differences in emergent coronary angiographic findings according to the presence or absence of ST depression in the inferior or lateral leads, or both, and location of the leads showing ST depression on admission electrocardiograms in patients with anterior AMI. The coronary angiographic features of patients with this ECG finding greatly support a poor prognosis. In patients with anterior AMI, analysis of ST depression on an admission electrocardiogram should be routinely performed because it is useful in predicting coronary anatomy, the extent of infarction, and its prognosis.

Adult↗
PubMed1995

Age-dependent reduction of Bcl-2 expression in peripheral T cells of lpr and gld mutant mice.

Autoimmune-prone lpr and gld mice carry defects in the apoptosis-mediating cell surface molecule Fas and its ligand, respectively. These mice develop lymphadenopathy because of an age-related accumulation of nonmalignant CD4- CD8- T cells in the peripheral lymphoid organs, suggesting a role for Fas-mediated apoptosis in peripheral T cell homeostasis. However, these accumulating cells are more susceptible to apoptosis ex vivo than peripheral T cells from control mice. To investigate the influence of additional regulatory elements on defects in the Fas-mediated apoptosis pathway, we analyzed the expression of Bcl-2 protein, a repressor of apoptosis, in T cells of lpr and gld mice. The expression levels of Bcl-2 in peripheral T cells of aged lpr and gld mice were significantly reduced when compared with their normal counterparts. Bcl-2 expression decreased with age in peripheral T cells, but not in thymocytes, suggesting that down-regulation of Bcl-2 protein occurs in the periphery. Analysis of T cell subsets indicated that CD4+ and CD4- CD8- T cells expressed significantly reduced levels of Bcl-2, whereas CD8+ cells maintain high levels of Bcl-2 expression. However, all peripheral T cell subsets including CD8+ cells were susceptible to glucocorticoid-induced apoptosis, indicating that there is no direct correlation between the levels of Bcl-2 expression and susceptibility to glucocorticoid-induced apoptosis. These studies suggest the presence of complex regulatory mechanisms for lymphocyte apoptosis and survival.

Age Factors↗
PubMed1995

A thermodynamic study of mutant forms of Streptomyces subtilisin inhibitor. I. Hydrophobic replacements at the position of Met103.

The thermodynamic effects of replacing the Met residue at amino acid position 103 of Streptomyces subtilisin inhibitor with other non-polar aliphatic residues were studied by means of differential scanning calorimetry. All but the Leu mutant, which is as stable as the wild-type but has different cooperative units in the course of unfolding, showed destabilization in terms of free energy. Similar losses in free energy, however, were caused by different reasons, i.e. by increased entropy for the Ala mutant and by decreased enthalpy for the Ile mutant, with a tendency that increases in entropy are accompanied by increases in enthalpy. The gain in entropy that caused the largest loss in free energy for the Gly mutant was unexpectedly smaller than that for the Ala mutant. The changes in enthalpy and entropy induced by the mutations exhibited some correlations with hydrophobicity, while no clear correlation was found between the changes in free energy and hydrophobicity.

Bacterial Proteins↗
PubMed1995

A thermodynamic study of mutant forms of Streptomyces subtilisin inhibitor. II. Replacements at the interface of dimer formation, Val13.

Amino acid replacements in a homodimeric protein, Streptomyces subtilisin inhibitor, at the position of Val13, which is located at the center of the beta-sheet interface of the domain-domain interaction, changed both the overall stability and the denaturational scheme. All the mutant forms lost stability, losses in free energy at 82.21 degrees C at pH 7.0 obtained by calorimetric measurements ranging from 10.3 kcal (mol dimer)-1 for the Gly mutant, which involved a loss in enthalpy without a compensating loss in entropy, to 0.84 kcal (mol dimer)-1 for the Ile mutant, which involved comparable losses in enthalpy and entropy. A gain in enthalpy for the Ala mutant was overcome by a gain in entropy, resulting in a loss in free energy by 6.78 kcal (mol dimer)-1. It was found that decreases in enthalpy and entropy showed good correlation with increasing side-chain hydrophobicity, while no such correlation was present for free energy. Replacements with Gly, Ala, Met and Phe altered the thermal denaturational scheme from N2 reversible 2D, which was the case for the Leu and Ile mutants as well as for the wild-type, to N2 reversible 2N* reversible 2D, where the first step can be regarded as a dissociation of the native dimer followed by a major unfolding in the second step. The free energy acquired by forming the dimer was estimated to be 2.03 kcal mol-1 for the Ala mutant at 66.95 degrees C at pH 9.5 and lower for the other three mutants.

Bacterial Proteins↗
PubMed1995

A thermodynamic study of mutant forms of Streptomyces subtilisin inhibitor. III. Replacements of a hyper-exposed residue, Met73.

Amino acid replacements of Met73, which is hyper-exposed in the native structure, with Asp, Glu, Lys, Gly, Ala, Val, Leu or Ile changed the stability of Streptomyces subtilism inhibitor by +1.60 to -0.94 kcal/mol-1 in free energy at 82.21 degrees C at pH 7.0, with higher hydrophobicity of the replacing amino acid side-chain showing a correlation with lower stability. Thermodynamic parameters obtained from detailed calorimetric analyses gave a nearly proportional relation between the entropy change and the enthalpy change of denaturation, i.e. T delta delta S degrees = -0.03 (+/- 0.11) + 1.14 (+/- 0.03) delta delta H, with the linear correlation coefficient 0.996 for 18 data points. This proportionality observed uniquely for the substitutions at position 73 was caused primarily by the water/side-chain interaction, or hydration effect, which can account for the majority of the changes in enthalpy and entropy induced by the mutations.

Bacterial Proteins↗