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Biomedical subjects

T Tamura

Publications and source records attributed to T Tamura.

At least 883 records · Page 49Linked to original sources
PubMed1991

Time course and clinical significance of marked left axis deviation in airline pilots.

The purpose of this study was to examine the time course and evaluate the clinical significance of marked left axis deviation (LAD) in airline pilots. The study group consisted of 30 Japan Airlines' pilots with marked LAD, identified from a group of 1,700 who are now 35 years of age or older. The mean age at examination was 48.5 +/- 5.7 years [corrected] and the mean observation period was 22.6 +/- 5.6 years [corrected]. The prevalence rate of marked LAD was 1.8%. In 20%, the axis remained unchanged, and in 70%, LAD progressed either gradually or suddenly. All subjects were examined by exercise testing and 26 had echocardiograms. Two pilots (6.7%) were found to have organic heart disease (hypertension), which was much lower than the rate reported previously. In these individuals, the onset of marked LAD was noted more than 10 years before hypertension was detected. No progression to complete left bundle branch block, nor any form of AV block, was observed among these subjects. No cardiac events or death occurred during the study period.

Adult↗
PubMed1991

The development of a treatment model for lymph node metastasis in nude mice transplanted with rat fibrosarcoma clone A.

We have tried to establish a model for lymph node metastasis in nude mice transplanted with clone A of methylcholanthrene-induced rat fibrosarcoma. Tumor cells transplanted either subcutaneously or intrafootpad metastasized exclusively to the lymph nodes in nude mice treated with antiasialo GM1 antiserum. In the experiments of intrafootpad transplantation, all the mice died of disseminated lymph node metastasis if the leg was not resected, or was resected more than 3 weeks after the transplantation of clone A. Some mice whose legs were amputated 1 or 2 weeks after transplantation could be cured by amputation alone. The maximum effective dose of in vitro active drug could improve the survival in mice, and 3/5, 4/5, and 3/5 mice treated with MMC, ACNU and CDDP respectively were cured even if their legs were amputated 3 weeks after transplantation. This tumor-bearing animal system was considered to provide a valuable experimental model for lymph node metastasis.

Amputation, Surgical↗
PubMed1991

[Evaluation of modern therapy for neuroblastoma].

The clinical results were evaluated periodically in 50 cases of neuroblastoma, 4 survived cases out of 15 from 1965 to 1971, 6 survived of 16 (38%) from 1972 to 1982 and 11 survived of 19 (58%) after 1983. In the early period, before 1971, our systemic wide resection was not performed. From 1972, we operated on by our wide resection's technique which based on to preserve main vessels from tumor and lymph nodes. To separate the vessels from the lymph nodes was begun from both iliaca vessels to caeliac vessels. The systemic wide resection might contribute to improve survival rate from 1972 to 1982, however, all of 7 cases in stage IV did not survive. The best result after 1983, 58% survival rate, depends on new intensive chemotherapy accompanying with autologous bone marrow transplantation. All of 3 cases in stage III and 5 of 11 cases in stage IVA survived and better survival rates. Five alive cases in stage IVA received delayed wide resection after 3 or 4 cycles of new regimen A1, and then underwent bone marrow transplantation preconditioned by Melphalan .

Child, Preschool↗
PubMed1991

[The second report on Japanese abroad with psychiatric problems: air transportation of Japanese with mental disorders in western Europe].

This is to report on airline travel processes experienced with two Japanese psychotics (schizophrenic) abroad who were treated by the local consulates of Japan, and escorted by Japanese psychiatrists from April to May in 1989. A comparative analysis was made of the two cases from the following six points of view: psychopathology concerning travel, psychiatric evaluation at the time of travel, access to local psychiatric medical services, trust between the patient and escorting physician, method of administering drugs, and cooperation in strategy with the airline company. Results indicate that the following three points are crucial in the air transportation of Japanese psychotics: 1) Establishment of patient-escorting physician trust relationship, 2) Adequate sedation through sufficient administration of tranquilizers, 3) Establishment of communication and close cooperation with the airline company.

Adult↗
PubMed1991

[Feasibility study of quality of life (QOL) instrument in patients with advanced lung cancer].

We have studied the feasibility of the QOL measurement for the group of patients with advanced lung cancer using the QOL questionnaires modified from FLIC (Functional Living Index Cancer). The 16-items instrument showed that the Cronbach's alpha of all categories were over 0.6. as the quality of reliability. Using the principal component method of multivariate analysis, four major factors were identified as a part of the construct validity. We concluded that the QOL of patients with advanced lung cancer under the clinical research setting can be evaluated using this questionnaires even in Japan which has different cultural background from the Western Countries.

Adult↗
PubMed1990

Purification of N-terminal hexapeptide of big gastrin from human urine.

We previously demonstrated that extremely high amounts of N-terminal big gastrin (G-34) fragments are excreted in human urine and three of them are N-terminal octa-, nona-, and decapeptide of G-34. Our subsequent examination revealed that there exists a considerable amount of another N-terminal G-34 fragment in urine, less hydrophobic than the three peptides. We purified this fragment from urine of an achlorhydric patient and determined the structure: less than Glu-Leu-Gly-Pro-Gln-Gly. The purification was carried out by Sep-Pak C18 cartridges, Sephadex G-25, and reverse phase HPLC. The structure was determined by a combination of amino acid analysis, amino acid sequence analysis, and mass spectral analysis. N-terminal hexapeptide of G-34 is the second richest component of urinary N-terminal G-34 fragments next to N-terminal octapeptide of G-34 in normal subjects.

Achlorhydria↗
PubMed1990

Structure of the 68-kDa neurofilament gene and regulation of its expression.

The complete structure of the mouse 68-kDa neurofilament (NF-L) gene was elucidated. We cloned cDNAs corresponding to 3.5- and 2.3-kb NF-L mRNA, including their polyadenylation sites. Sequence analysis revealed that these NF-L mRNAs arose from the alternative use of two polyadenylation sites in exon 4. Promoter analysis using NF-L promoter-beta-galactosidase fusion plasmids determined regions responsible for its basic promoter activity, which were located between -328 and -36 base pairs from the transcription initiation site. These promoter fusion plasmids induced a significant level of beta-galactosidase in NF-nonproducing C6 cells as well as in NF-producing PC12h cells. The in vitro transcription assay using HeLa cell extract also showed that this promoter exhibited strong transcriptional activity. Little difference in NF-L mRNA stability was observed between the two cells. However, nuclear run-off assay revealed that the NF-L gene was not transcribed in NF-nonproducing C6 cells. These data suggest that the strong promoter activity of the NF-L gene is repressed in vivo at the transcription initiation level in a tissue-specific manner.

Animals↗
PubMed1990

Dual effects of staurosporine on arachidonic acid metabolism in rat peritoneal macrophages.

Staurosporine is a microbial anti-fungal alkaloid having a most potent inhibitory activity on protein kinase C and is recently found as a non-12-O-tetradecanoylphorbol-13-acetate (non-TPA)-type tumor promoter of mouse skin, although tumor promotion induced by a TPA-type tumor promoter teleocidin is suppressed by staurosporine. When rat peritoneal macrophages were incubated in the medium containing various concentrations of staurosporine, prostaglandin E2 production and release of radioactivity from [3H]arachidonic acid-labeled macrophages were stimulated at concentrations of 1 and 10 ng/ml. But higher concentrations of staurosporine such as 100 and 1000 ng/ml showed no stimulative effect on prostaglandin E2 production although cytoplasmic free calcium levels were increased in a dose-dependent manner. Staurosporine-induced stimulation of prostaglandin E2 production was inhibited by treatment with cycloheximide, suggesting that a certain protein synthesis is prerequisite for the stimulation of arahcidonic acid metabolism. At higher concentrations (100 and 1000 ng/ml), staurosporine inhibited TPA-type tumor promoter (TPA, teleocidin and aplysiatoxin)-induced stimulation of arachidonic acid metabolism probably due to the inhibition of protein kinases. Tumor promotion activity and anti-tumor promotion activity of staurosporine might be explained by the fact that the lower concentrations of staurosporine stimulate arachidonic acid metabolism and the higher concentrations of staurosporine inhibit the tumor promoter-induced arachidonic acid metabolism, respectively.

Alkaloids↗
PubMed1990

Isolation of complementary DNAs encoding a cerebellum-enriched nuclear factor I family that activates transcription from the mouse myelin basic protein promoter.

A nuclear factor I (NFI) binding sequence in the myelin basic protein (MBP) promoter is required for brain-specific transcription. In the present study, we isolated multiple cDNAs encoding a family of NFI, NFI-B, from mouse brain cDNA libraries. These clones contain unique nucleotide sequences at their 5', 3', or middle portions, presumably as a result of alternative splicing. The entire sequence of NFI-B suggests that NFI-B is a mouse counterpart of NFI-L, which was previously isolated from rat liver. NFI-B is highly enriched in the cerebellum, in contrast with a ubiquitous NFI, CTF/NF-I. NFI-B proteins translated in vitro could bind to the MBP NFI site. Furthermore, we demonstrated by transfection experiments that NFI-B activated transcription from transfected MBP promoter in neuronal/glial NG108-15 cells.

Amino Acid Sequence↗
PubMed1990

Pharmacological studies on novel muscarinic agonists, 1-oxa-8-azaspiro[4.5]decane derivatives, YM796 and YM954.

We have investigated the pharmacological profiles of the novel muscarinic agonists, 1-oxa-8-azaspiro[4.5]decane derivatives, YM796 (2,8-dimethyl-3-methylene) and YM954 (2-ethyl-8-methyl-3-oxo). These compounds, like the putative M1 agonists, RS86 and AF102B, inhibited [3H]pirenzepine binding to cerebral cortical membranes in the micromolar range and weakly inhibited [3H]quinuclidinyl benzylate binding to cerebellar membranes. Their (-) isomers had Hill coefficients lower than 1.0. (+/-)-YM796, (+/-)-YM954 and RS86, but not AF102B, stimulated phosphoinositide hydrolysis in hippocampal slices, an effect which is mainly linked to M1 receptors. (+/-)-YM796 (0.031 mg/kg p.o.) and (+/-)-YM954 (0.016 mg/kg p.o.) reversed the cognitive impairment in nucleus basalis magnocellularis-lesioned rats in a passive avoidance task more effectively than did RS86 and AF102B. Similar results were obtained in scopolamine-treated rats. Finally, (+/-)-YM796 was weaker than (+/-)-YM954 and RS86 in the induction of tremor, hypothermia and contraction of isolated ileum, which are mainly mediated by M2 and/or M3 receptors. These results suggest that (+/-)-YM796, (+/-)-YM954 and RS86 have M1 agonistic activity in central nervous system and that (+/-)-YM796 has relatively weak M2 and/or M3 agonistic activity.

Animals↗
PubMed1990

Possible mechanism of nuclear translocation of proteasomes.

Proteasomes (multicatalytic proteinase complexes), which are identical to the ubiquitous eukaryotic 20S particles, are localized in both the cytoplasm and the nucleus, but the mechanism of their co-localization in the two compartments is unknown. On examination of the primary structures of subunits of proteasomes, a consensus sequence for nuclear translocation of proteins, X-X-K-K(R)-X-K(R) (where X is any residue), was found to be present in some subunits and to be highly conserved in the subunits of a wide range of eukaryotes. In addition, proteasomal subunits were found to bear a cluster of acidic amino acid residues and also a potential tyrosine phosphorylation site that was located in the same polypeptide chain as the nuclear location signal. These structural properties suggest that two sets of clusters with positive and negative charges serve to regulate the translocation of proteasomes from the cytoplasm to the nucleus, and that phosphorylation of tyrosine in certain subunits may play an additional role in transfer of proteasomes into the nucleus.

Amino Acid Sequence↗
PubMed1990

Proteasomes are essential for yeast proliferation. cDNA cloning and gene disruption of two major subunits.

The cDNAs encoding two major subunits, named YC1 and YC7-alpha, of yeast proteasomes (multicatalytic proteinase complexes) were isolated and sequenced. As deduced from their nucleotide sequences, YC1 and YC7-alpha consist of 288 and 252 amino acid residues with calculated molecular weights of 31,534 and 27,999, respectively. They showed marked sequence homology to other eukaryotic proteasome components, suggesting that proteasomes are composed of a family of subunits with the same evolutional origin. To obtain information on the physiological role of proteasomes, we disrupted the chromosomal genes of YC1 and YC7-alpha of yeast cells independently, using isolated cDNA clones. Disruption of the coding region of one copy of the YC1 gene in diploid yeast created a recessive lethal mutation, but disruption of the 3'-noncoding region of the gene had no effect on cell proliferation. Disruption of the YC7-alpha gene also had a lethal effect on haploid yeast cells. These findings demonstrated that YC1 and YC7-alpha are both encoded by a single copy gene and that these genes are essential for proliferation of yeast cells.

Amino Acid Sequence↗
PubMed1990

cDNA cloning and sequencing of component C8 of proteasomes from rat hepatoma cells.

The primary structure of component C8 of rat proteasomes (multicatalytic proteinase complexes) has been determined by sequencing on isolated cDNA clone. C8 consists of 255 amino acid residues with a calculated molecular weight of 28,417. These values are consistent with those obtained by protein chemical analyses. Computer-assisted homology comparison showed that C8 is a new protein, differing from all proteins reported so far. The overall amino acid sequence of C8 resembles those of most other components of proteasomes reported, such as components C2, C3 and C9 of rat proteasomes and certain components of other eukaryotic proteasomes, such as those of Drosophila and yeast, but shows little similarity with component C5 of rat proteasomes. C8 showed particularly close structural similarity to component YC1 of yeast proteasomes, suggesting that C8 has been highly conserved during evolution and functions ubiquitously in all eukaryotes.

Amino Acid Sequence↗
PubMed1990

Effect of divalent cations on NADH-dependent and NADPH-dependent cytochrome b5 reduction by hepatic microsomes.

The effect of Ca2+ or Mg2+ on cytochrome b5 reduction by porcine liver microsomes was examined using trypsin-solubilized cytochrome b5 as a substrate. The reduction of exogenous cytochrome b5 by microsomes was low at 1.2 microM cytochrome b5 (3.9 or 2.7 nmol/min/mg protein, respectively, with NADH or NADPH). The addition of CaCl2 greatly enhanced either NADH-dependent or NADPH-dependent cytochrome b5 reduction. At 2 mM CaCl2, the reduction rate was increased to 23- or 18-fold of control, respectively with NADH or NADPH. The concentration for half-maximal effect (EC50) was 0.5 or 0.6 mM in the NADH or NADPH systems, respectively. MgCl2 also stimulated cytochrome b5 reduction with a EC50 value of 1.0 mM in the NADH system or 0.6 mM in the NADPH system. The comparison with the result with KCl indicated that the activation by CaCl2 or MgCl2 is caused mainly by their divalent cation moiety. The Km value for cytochrome b5 was decreased and the Vmax was increased by calcium with either the NADH- or the NADPH-dependent system. NADH-ferricyanide reductase activity was not affected by calcium, but NADPH-ferricyanide reductase activity was stimulated as well as NADPH-cytochrome c reductase activity. In the presence of Triton X-100, divalent cations were inhibitory in NADH-dependent cytochrome b5 reduction, and in contrast, stimulative in NADPH-dependent reaction. These findings suggest that the activation of cytochrome b5 reduction by divalent cations in the NADH system is mainly due to an increasing accessibility of the substrate, and in the NADPH system, in addition to this, a direct effect of divalent cations on NADPH-cytochrome P450 reductase is also involved.

Animals↗
PubMed1990

Regulatory role of CD4/L3T4 molecules in IL-2 production by affecting intracellular Ca2+ concentration of T cell clone stimulated with soluble anti-CD3.

To elucidate the role of CD4 molecule in T cell activation, the effect of anti-CD4 on T cell IL-2 production was examined by using an alloreactive Th clone. The alloreactive T cell used in the present experiments produced IL-2 in response to soluble anti-CD3 epsilon-chain (anti-CD3) without accessory cell or insoluble antibody carrier. The IL-2 production was suppressed by the addition of anti-CD4 in cultures. An intracellular free Ca2+ concentration ([Ca2+]i) of the T cell clone was elevated by anti-CD3 stimulation, but the elevation was suppressed in the presence of anti-CD4. When the clone was stimulated in Ca2(+)-free medium, the elevation of [Ca2+]i was not observed. When Ca2+ influx was induced by calcium ionophore A23187 or ionomycin, the clone produced IL-2 in response to anti-CD3 in the presence of anti-CD4. When polyclonal T cell line or several other alloreactive T cell clones were examined for their anti-CD3 response, essentially the same results as mentioned above were obtained. Taken together, these results suggest that the slow and sustained elevation of [Ca2+]i is an essential signal for IL-2 production of T cells, and that anti-CD4 suppresses the IL-2 production by interfering the [Ca2+]i elevation. The significance of CD4 molecules in murine T cell activation was discussed.

Animals↗
PubMed1990

cDNA cloning and sequencing of component C9 of proteasomes from rat hepatoma cells.

The nucleotide sequence of component C9 of rat proteasomes (multicatalytic proteinase complexes) has been determined from a recombinant cDNA clone isolated by screening a Reuber H4TG hepatoma cell cDNA library using synthetic oligodeoxynucleotide probes corresponding to partial amino acid sequences of the protein. The predicted sequence of C9 consists of 261 amino acid residues with a calculated molecular weight of 29,496. The C9 component is a novel protein, differing from known proteins, but its primary structure resembles those of other proteasome components, including C2, C3 and C5, although its similarity to C5 is relatively low, suggesting that proteasomes consist of a family of proteins that have evolved from a common ancestor.

Amino Acid Sequence↗
PubMed1990

cDNA cloning and sequencing of component C5 of proteasomes from rat hepatoma cells.

Proteasomes are multicatalytic proteinase complexes consisting of a set of non-identical polypeptide subunits. A cDNA for component C5 of rat proteasomes was isolated by screening a Reuber H4TG hepatoma cell cDNA library using synthetic oligodeoxynucleotide probes corresponding to partial amino acid sequences of the protein. The polypeptide deduced from the open reading frame consisted of 240 amino acid residues with a calculated molecular weight of 26,479. Computer analysis revealed little similarity of C5 to other proteins reported so far. The primary structure of C5 showed partial sequence homology to that of another component C3, but no regions of homology with the sequence of component C2. Thus C5 is concluded to be a new type of subunit of the proteasome complex.

Amino Acid Sequence↗