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T Asakura

Publications and source records attributed to T Asakura.

At least 73 records · Page 4Linked to original sources
PubMed1999

C alpha and C beta carbon-13 chemical shifts in proteins from an empirical database.

We have constructed an extensive database of 13C C alpha and C beta chemical shifts in proteins of solution, for proteins of which a high-resolution crystal structure exists, and for which the crystal structure has been shown to be essentially identical to the solution structure. There is no systematic effect of temperature, reference compound, or pH on reported shifts, but there appear to be differences in reported shifts arising from referencing differences of up to 4.2 ppm. The major factor affecting chemical shifts is the backbone geometry, which causes differences of ca. 4 ppm between typical alpha-helix and beta-sheet geometries for C alpha, and of ca. 2 ppm for C beta. The side-chain dihedral angle chi 1 has an effect of up to 0.5 ppm on the C alpha shift, particularly for amino acids with branched side-chains at C beta. Hydrogen bonding to main-chain atoms has an effect of up to 0.9 ppm, which depends on the main-chain conformation. The sequence of the protein and ring-current shifts from aromatic rings have an insignificant effect (except for residues following proline). There are significant differences between different amino acid types in the backbone geometry dependence; the amino acids can be grouped together into five different groups with different phi, psi shielding surfaces. The overall fit of individual residues to a single non-residue-specific surface, incorporating the effects of hydrogen bonding and chi 1 angle, is 0.96 ppm for both C alpha and C beta. The results from this study are broadly similar to those from ab initio studies, but there are some differences which could merit further attention.

Animals↗
PubMed1999

Caspase-3 activation during apoptosis caused by glutathione-doxorubicin conjugate.

Glutathione-doxorubicin (GSH-DXR) effectively induced apoptosis in rat hepatoma cells (AH66) at a lower concentration than DXR. After 24 h of drug treatment, DNA fragmentation of the cells was observed at the concentration of 1.0 microM DXR or 0.01 microM GSH-DXR. Increase in caspase-3 activity and DNA fragmentation were observed within 12 h and 15 h after treatment with either drug. Intracellular caspase-3 activity was increased in a dose-dependent manner after treatment with DXR or GSH-DXR, and caspase-3 activity correlated well with the ability to induce DNA fragmentation. When the cells were treated with either DXR or GSH-DXR for only 6 h, apoptotic DNA degradation and caspase-3 activation occurred 24 h after treatment. DNA fragmentation caused by these drugs was prevented completely by simultaneous treatment with the caspase-3 inhibitor, acetyl-Asp-Glu-Val-Asp-aldehyde (DEVD-CHO), at 10 microM. By contrast, DNA fragmentation was not prevented by the caspase-1 inhibitor, acetyl-Tyr-Val-Ala-Asp-aldehyde (YVAD-CHO), at the same concentration as DEVD-CHO, and caspase-1 was not activated at all by the treatment of AH66 cells with both DXR and GSH-DXR. These results demonstrate that DXR and GSH-DXR induce apoptotic DNA fragmentation via caspase-3 activation, but not via caspase-1 activation, and that GSH-DXR enhances the activation of caspase-3 approximately 100-fold more than DXR. Moreover, the findings suggested that an upstream apoptotic signal that can activate caspase-3 is induced within 6 h by treating AH66 cells with the drug.

Animals↗
PubMed1999

Similar and differential behaviour between the nectin-afadin-ponsin and cadherin-catenin systems during the formation and disruption of the polarized junctional alignment in epithelial cells.

BACKGROUND: We have recently identified a novel cell-cell adhesion system, named NAP system, which is localized at cadherin-based cell-cell adherens junctions (AJs). The NAP system is composed of at least nectin, afadin and ponsin. Nectin is an immunoglobulin-like cell adhesion molecule. Afadin is an actin filament-binding protein which associates nectin with the actin cytoskeleton. Ponsin is an afadin-binding protein which furthermore binds to vinculin and provides a possible linkage of nectin-afadin to cadherin-catenin through vinculin. We compared here the behaviour of the NAP and cadherin-catenin systems during the formation and disruption of the polarized junctional alignment in epithelial cells. RESULTS: At the early stage of the formation of the polarized junctional alignment in MTD-1 A cells, primordial spot-like junctions were formed at the tips of thin cellular protrusions radiating from adjacent cells. Nectin, afadin, ponsin, cadherin and catenin were simultaneously recruited to these junctions. As the cell polarization proceeded, the spot-like junctions were gradually fused to form belt-like AJs where all these proteins were concentrated. The disruption of cell-cell AJs in MDCK cells by culturing at a low Ca2+ concentration caused rapid endocytosis of cadherin, but not that of nectin or afadin. Addition of 12-O-tetradecanoylphorbol-13-acetate to the cells formed a tight junction-like structure where nectin and afadin, but not cadherin, accumulated. CONCLUSION: These results indicate that the NAP and cadherin-catenin systems show similar and differential behaviour during the formation and disruption of the polarized junctional alignment in epithelial cells.

Animals↗
PubMed1999

Insulin-like growth factor-1 content and pattern of expression correlates with histopathologic grade in diffusely infiltrating astrocytomas.

Studies of experimental tumorigenesis have strongly implicated signaling of the insulin-like growth factor 1 (IGF-1) as a key component in astrocytic neoplasia; however, its role in the growth of low-grade and malignant human tumors is not well understood. Correlative analyses of IGF-1, p53, and Ki-67 (MIB-1) immunohistochemistry and IGF-1 receptor (IGF-1R) mRNA expression were performed to examine the cellular pattern of IGF-1 signaling in 39 cases of astrocytoma (World Health Organization grades II-IV). Tumor cells expressing IGF-1 and IGF-1R were present in all tumor grades. The proportion of tumor cells that expressed IGF-1 correlated with both histopathologic grade and Ki-67 labeling indices, while expression of IGF-1R mRNA correlated with Ki-67 indices. In cases where stereotactic tissue sampling could be identified with a specific tumor area by neuroimaging features, the numbers of IGF-1 immunoreactive cells correlated with the tumor zones of highest cellularity and Ki-67 labeling. In glioblastomas, the localization of IGF-1 immunoreactivity was notable for several features: frequent accentuation in the perivascular tumor cells surrounding microvascular hyperplasia; increased levels in reactive astrocytes at the margins of tumor infiltration; and selective expression in microvascular cells exhibiting endothelial/pericytic hyperplasia. IGF-1R expression was particularly prominent in tumor cells adjacent to both microvascular hyperplasia and palisading necrosis. These data suggest that IGF-1 signaling occurs early in astroglial tumorigenesis in the setting of cell proliferation. The distinctive correlative patterns of IGF-1 and IGF-1R expression in glioblastomas also suggest that IGF-1 signaling has an association with the development of malignant phenotypes related to aberrant angiogenesis and invasive tumor interactions with reactive brain.

Astrocytoma↗
PubMed1999

Psychosomatic symptoms of Japanese working women and their need for stress management.

This study was conducted to clarify Japanese female workers' psychosomatic symptoms including women-specific complaints and their need for stress management as part of occupational health services (OHS). In 1997, a survey was conducted in which a questionnaire was sent to 1108 full-time female workers. The response rate was 92.1%. They classified their own health status excellent (26.0%), good (60.4%), fair (9.6%), or bad (1.6%). They also reported their irritability (25.3%) and depression (15.6%). There were high rates of complaints of eye discomfort (53.6%), fatigue (44.1%), headache (43.0%), and menstrual pain (32.5%). Such symptoms were associated with irritability or depression. Amount of overtime works, marital status in the 30-44 age group, the presence of children were found to be important factors in determining health status. Regarding the needs for occupational health services, 22.2% of respondents answered they needed mental health management (MHM). Compared with other services, such as management of lifestyle diseases, gynecological diseases, cancer screenings and counseling on nutrition and exercise, the need for MHM was low. The preferred personnel were female doctors and nurses. Workers who performed frequent overtime work had a greater need for MHM. The most preferred means of receiving MHM was personal counseling by doctors (not psychologists) and nurses.

Adult↗
PubMed1999

Calpain inhibitor causes accumulation of ubiquitinated P-glycoprotein at the cell surface: possible role of calpain in P-glycoprotein turnover.

P-glycoprotein (Pgp) is a plasma-membrane glycoprotein that confers multi-drug resistance (MDR) on cells and displays ATP-driven drug pumping. The possible contribution of calpain-mediated proteolytic pathways to the functional regulation of the Pgp molecule was evaluated using K562/DXR, MDR cells. N-Acetyl-L-leucyl-L-leucyl-norleucinal was effluxed by Pgp, but N-benzyloxycarbonyl-L-leucyl-L-leucinal (zLLal), an inhibitor of calpain, retarded the degradation of Pgp leading to accumulation of the molecule largely at the cell surface membrane. Treatment with brefeldin A did not obstruct the zLLal-induced Pgp accumulation. NH4Cl increased the cytoplasmic Pgp level, with a slight to significant decrease at the cell surface membrane. Ubiquitin-ELISA and western blot analysis confirmed that the Pgp molecule, which accumulated mainly at the cell surface, was ubiquitinated. However, lactacystin did not show any accumulation of Pgp in either the cytoplasm or the cell surface membrane, suggesting that the proteasome did not participate in the phenomenon. Additionally, the Pgp was limitedly proteolyzed by calpain into two 98 kDa and 69 kDa, fragments within one minute. Despite the increased accumulation of Pgp at the cell surface after treatment with calpain inhibitor, the cytoplasmic doxorubicin level of the cells treated with a calpain inhibitor was higher than that of non-treated cells and approached that of parental cells. These results indicated that calpain involved Pgp turnover and that calpain inhibition induced ubiquitinated Pgp-accumulation mainly at the cell surface membrane with a reduction in its own functions suggesting that the modulation of Pgp-turnover involves MDR-reversal by another approach.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

[Treatment and prognosis of T 4 renal cell carcinoma].

BACKGROUND: We studied the cases with T 4 renal cell carcinoma (RCC) to characterize the factors associated with prolonged survival and to clarify the indication of extended nephrectomy. MATERIALS AND METHODS: The study population consisted of 53 patients (44 male and 9 female) with pT 4 RCC treated at the Yokohama City University Hospital and its affiliated hospitals from 1965 to 1994. Survival rates were analyzed with respect to clinicopathological factors (patient age, sex, symptom, tumor growing type, tumor size, histological grade, cell type, structural type, lymph node metastasis, vein invasion, distant metastasis and extended nephrectomy). RESULTS: One-year, 2-years, and 3-years survival rates of the cases with T 4 RCC were 30.4%, 16.4%, and 9.4% respectively. In univariate analysis, improved survival were correlated with no extra-urinary symptom (Logrank: p = 0.0048, Wilcoxon: p = 0.0423), no lymphnode metastasis (Logrank: p = 0.1045, Wilcoxon: p = 0.0199), no distant metastases (Logrank: p = 0.0007, Wilcoxon: p = 0.0006), and enforcement of extended nephrectomy (Logrank: p = 0.0018, Wilcoxon: p = 0.0008). In 28 cases with extended nephrectomy, improved survival was correlated with no extra-urinary symptom, no abdominal wall invasion and no distant metastases. In 5 cases with more than 3 year survival after extended nephrectomy, 4 cases were found to have no distant metastases at the time of operation. Non-operative therapy including interferon for 20 cases without extended nephrectomy were almost ineffective. CONCLUSIONS: These results indicate that if curative excision for T 4 RCC cases without distant metastases could be done, some patients might be appropriate candidates for extended nephrectomy.

Aged↗
PubMed1999

[The analysis for surgical procedures of coronary-artery bypass grafting: selection of graft materials].

We analyzed 222 patients undergoing coronary artery bypass grafting (CABG) in our institute. Our selection of graft materials consists of only one arterial conduit and one or more saphenous vein grafts (SVG). An arterial conduits (left internal thoracic artery (LITA) was mainly used for the left anterior descending coronary artery (LAD), while a SVG was used for coronary arterial branch. Our approach was evaluated by the mid-term prognosis as well as cardiac events. Seventy-one percent of patients with CABG could be followed. The graft patency rate was better for ITA grafts than for SVG (97.8% vs 88%). The incidence of late cardiac events was lower in patients with the LITA, to the LAD. Furthermore, these patients had a better survival rate at 4 years comparing with patients who had vein bypass grafts alone. We suggest that this selection of graft materials may be accepted in CABG for the good quality, avoiding the cardiac events.

Adult↗
PubMed1999

[Changes in diameter size and F-actin expression in the myocytes of patients with diabetes and streptozotocin-induced diabetes model rats].

Diabetes mellitus may be an independent risk factor for disturbance of cardiac function, but the detailed mechanism remains unclear. In the present study, histological examinations were carried out on 25 hearts from diabetes model rats as well as myocardial biopsy materials from patients with diabetes (n = 25). The mean diameter of the cardiac myocytes in humans was 12.2 +/- 0.5 microns in the control group of patients without diabetes mellitus or hypertension (n = 6), 13.7 +/- 0.8 microns in the hypertension group (n = 3), 9.0 +/- 1.7 microns in the diabetes group (n = 8), and 11.9 +/- 2.0 microns in the diabetes with hypertension group (n = 8). The cardiac myocytes of diabetic patients appeared to be atrophic. Comparison of the size of myocytes in the control rats vs streptozotocin-induced diabetes model rats (n = 7, each) was 5.4 +/- 0.2 vs 5.2 +/- 0.3 microns at 2 weeks; 5.9 +/- 0.1 vs 4.9 +/- 0.9 microns at 12 weeks, and 5.7 +/- 0.1 vs 4.0 +/- 0.2 microns at 24 weeks, respectively, and gradually decreased in streptozotocin rats with aging. Immuno-histochemistry with phaloidin was used to assess F-actin in the cardiac myocytes. The relative cross-sectional area of F-actin in the cardiac myocytes of streptozotocin rats was compared to that in non-streptozotocin rat myocytes. F-actin fluorescence in streptozotocin rats was 89.9 +/- 3.9% at 2 weeks, 77.9 +/- 6.4% at 12 weeks, and 56.8 +/- 5.7% at 24 weeks, indicating a decrease in F-actin. These results suggest that the smaller myocytes observed in patients with diabetes and streptozotocin rats are related to the decrease in F-actin in myocytes.

Actins↗
PubMed1998

The structure of the melittin tetramer at different temperatures--an NOE-based calculation with chemical shift refinement.

The structure of the bee venom peptide melittin has been determined in water at pH 6.0, 50 mM sodium phosphate, at various temperatures. At all temperatures studied, the peptide is tetrameric, and consists of two helical regions (residues 2-11 and 13-23) with an unstructured C-terminal region. The connection between the helices (residues 11-13) is well defined. At 30 degrees C, the structure of the monomeric unit has been characterised using NOEs, and a family of structures is presented (root-mean-square deviation to the mean structure 1.4 A over the structured residues), with low NOE violations and good stereochemistry. The angle between the helices is 46+/-13 degrees, and the structure is very similar to the previously determined crystal structure of the aqueous tetramer. The peptide forms a tetramer that is made up from a dimer of dimers. The structure of the dimeric unit has been determined, using a novel joint refinement of intermonomer NOEs and chemical shifts. The relative position of the monomeric units in the dimer is different from that in the crystal, with less direct contact between monomers. As the temperature is raised to 70 degrees C, the peptide remains tetrameric, but the monomer units start to separate, as shown by a reduction in intermonomer NOE intensities and chemical shifts. The structural changes have been characterised: over the temperature range studied, the monomers separate by approximately 2.0 A. This movement may have implications for the mechanism by which melittin inserts into membranes.

Amino Acid Sequence↗
PubMed1998

Molecular cloning and characterization of the noncatalytic subunit of the Rab3 subfamily-specific GTPase-activating protein.

We recently purified and characterized from rat brain a GTPase-activating protein (GAP) specific for the Rab3 small G protein subfamily implicated in Ca2+-dependent exocytosis. Rab3 GAP showed two bands with Mr of about 130,000 (p130) and 150,000 (p150) on SDS-polyacrylamide gel electrophoresis. p130, but not p150, showed the catalytic activity. Because p150 was likely the subunit of Rab3 GAP, here we cloned the cDNA of p150, determined its primary structure, and characterized it. The tissue and subcellular distribution patterns of p150 and p130 were similar, and both the proteins were enriched in the synaptic soluble fraction. p150 was co-immunoprecipitated with p130 from this fraction. Recombinant p150 formed a heterodimer with recombinant p130 as estimated by sucrose density gradient ultracentrifugation. Recombinant p150 neither showed the Rab3A GAP activity nor affected the activity of recombinant p130. When p150 and p130 were co-expressed in the cells, the subcellular localization of each protein did not change. These results indicate that p150 is the noncatalytic subunit of Rab3 GAP.

Amino Acid Sequence↗
PubMed1998

Adhesion mechanisms of resin to etched dentin primed with N-methacryloyl glycine studied by 13C-NMR.

The origin of the pH-dependent bond strength of the resin to etched dentin treated with N-methacryloyl glycine (NMGly) primer was studied by 13C-nuclear magnetic resonance (NMR) including spin-lattice relaxation time, T1, observation. When the dentinal collagen was suspended in the NMGly solution at pH = 1.6, the T1 values of all the carbons attributed to the NMGly species were significantly decreased. This indicated the presence of an interaction between the NMGly and the dentinal collagen. To obtain detailed information of this interaction, the 13C-NMR spectra of the NMGly were measured in the presence of the model compound for the collagen, (Pro-Pro-Gly)5 at pH = 1.7. The 13C-NMR peaks of the carbonyl carbons of the amide and carboxylic acid in the NMGly species shifted to a higher field and the T1 values decreased. Furthermore, when the molar ratio of (Pro-Pro-Gly)5 to NMGly was decreased from 1:1 to 1:3, the T1 values of the carbonyl carbon attributed to the carboxylic acid in the C-terminal Gly residue of the oligopeptide decreased dramatically. It can be construed that this indicated the formation of a hydrogen bond between the amide, -NH and the carboxylic acid of the NMGly species and the carboxylic acid of the C-terminal Gly residue of the oligopeptide.

Acid Etching, Dental↗
PubMed1998

Interactions of drebrin and gephyrin with profilin.

Profilin is an actin monomer-binding protein which stimulates actin polymerization. Recent studies have revealed that profilin interacts with VASP, Mena, Bnilp, Bnrlp, and mDia, all of which have the proline-rich domain. Here, we isolated three profilin-binding proteins from rat brain cytosol by glutathione S-transferase-profilin affinity column chromatography and identified them as Mena, drebrin, and gephyrin. These proteins had a proline-rich domain and directly interacted with profilin.

Amino Acid Sequence↗
PubMed1998

Isolation and characterization of a novel actin filament-binding protein from Saccharomyces cerevisiae.

We purified a novel actin filament (F-actin)-binding protein from the soluble fraction of Saccharomyces cerevisiae by successive column chromatographies by use of the 125I-labeled F-actin blot overlay method. The purified protein showed a minimum Mr of about 140 kDa on SDS-polyacrylamide gel electrophoresis and we named it ABP140. A search with the partial amino acid sequences of ABP140 against the Saccharomyces Genome Database revealed that the open reading frame of the ABP140 gene (ABP140) corresponded to YOR239W fused with YOR240W by the +1 translational frame shift. The encoded protein consisted of 628 amino acids with a calculated Mr of 71,484. The recombinant protein interacted with F-actin and showed the activity to crosslink F-actin into a bundle. Indirect immunofluorescence study demonstrated that ABP140 was colocalized with both cortical actin patches and cytoplasmic actin cables in intact cells. However, elimination of ABP140 by gene disruption did not show a deleterious effect on cell growth or affect the organization of F-actin. These results indicate that ABP140 is not required for cell growth but may be involved in the reorganization of F-actin in the budding yeast.

Actins↗
PubMed1998

Effect of erythrocytapheresis on arterial oxygen saturation and hemoglobin oxygen affinity in patients with sickle cell disease.

An important purpose of blood transfusion in patients with sickle cell disease is to improve arterial oxygen saturation (SaO2) and thereby reduce red cell sickling. To investigate the degree of improvement in SaO2 by blood transfusion, we determined the hemoglobin oxygen affinity, transcutaneous oxygen saturation (Tc-SO2), and pulse rate before and after automated partial exchange transfusion (erythrocytapheresis). In 13 patients with sickle cell disease who underwent 24 erythrocytapheresis procedures, the mean oxygen tension at half saturation (P50) was significantly reduced from 30.4 +/- 2.2 to 26.0 +/- 1.6 mm Hg (P< 0.01) immediately after exchange transfusion. Mean Tc-SO2 values increased from 96.2 +/- 2.8 to 98.5 +/- 2.1% (P< 0.01). Approximately 50% of the increase in Tc-SO2 after erythrocytapheresis could be explained by the increase in hemoglobin oxygen affinity. An increase in arterial oxygen pressure (PaO2) following erythrocytapheresis, suggested by the calculated PaO2 in this study, may explain some of the increase in Tc-SO2. We conclude that improvement in Tc-SO2 in patients with sickle cell disease resulted from changes in hemoglobin oxygen affinity as well as blood oxygen pressure following erythrocytapheresis.

2,3-Diphosphoglycerate↗