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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 649 records · Page 36Linked to original sources
PubMed1995

Molecular cloning of a cDNA clone encoding a phosphoprotein component related to the Ig receptor-mediated signal transduction.

We have shown previously that a 52-kDa phosphoprotein (p52) co-precipitated with Ig receptor (IgR)-associated MB-1 protein was inducibly phosphorylated by the stimulation with 12-O-tetradecanoyl-phorbol-13-acetate. By immunizing the 52-kDa protein co-precipitated with MB-1, we prepared a mAb (19-14), which can immunoprecipitate the p52 and the associated kinase molecule. Immune complex kinase assay with the 19-14 mAb showed that the p52 is associated with a novel kinase molecule and is involved in IgR-mediated signal transduction. Here we isolated a cDNA clone (alpha 4) from a murine bone marrow cDNA library in lambda gt-11 vector by the 19-14 mAb. The alpha 4 cDNA encodes a novel protein of 340 amino acids with multiple potential phosphorylation sites. The 1.4-kb alpha 4 mRNA is expressed in various cells including cell lines of B lineage, T lineage, monocytic, fibroblast, and normal organs such as liver, spleen, thymus, and brain. To study the molecule encoded by the alpha 4 cDNA, we produced a chimeric protein of the glutathione S transferase (GST)-alpha 4 in pGEX-3X expression vector. The 19-14 mAb binds to the GST-alpha 4 fusion protein. Rabbit anti-alpha 4 Ab prepared by immunizing the GST-alpha 4 fusion protein immunoprecipitated a 52-kDa phosphoprotein from WEHI-231 cells. The 52-kDa phosphoprotein immunoprecipitated by the anti-alpha 4 Ab is tightly associated with kinase activity that is similarly observed with the p52 protein reported previously. Moreover, the 52-kDa phosphoprotein immunoprecipitated with the anti-alpha 4 Ab is identical to the p52 by the protein comparison on non-equilibrium pH gradient gel electrophoresis/SDS-PAGE, isoelectric focusing/SDS-PAGE, and V8 protease mapping. The 52-kDa phosphoprotein is associated with functional components that are inducibly phosphorylated by anti-IgM stimulation. These results suggested that the alpha 4 gene-encoded molecule is functionally involved in the IgR-mediated signal transduction in B cells.

Amino Acid Sequence↗
PubMed1995

Flow capacity of internal mammary artery grafts: early restriction and later improvement assessed by Doppler guide wire. Comparison with saphenous vein grafts.

OBJECTIVES: The purpose of this study was to assess flow dynamics and flow capacities of internal mammary artery and saphenous vein grafts to the left anterior descending coronary artery. BACKGROUND: The postoperative flow capacity of internal mammary artery grafts to the left anterior descending coronary artery has been reported to be restricted compared with that of saphenous vein grafts in studies using radionuclide angiography. A recently developed Doppler guide wire has been used to analyze the flow dynamics of bypass grafts and to clarify the mechanism of this limited flow capacity. METHODS: Phasic flow velocity recordings were obtained in the midportion of the bypass graft and within the native left anterior descending artery, using a 0.018-in. (0.046-cm) 12-MHz Doppler guide wire, in 53 patients: 27 patients with an internal mammary artery graft (16 with a new graft assessed 1 month postoperatively and 11 with an old graft assessed at 1 year) and 26 patients with a saphenous vein graft (13 with a new graft assessed 1 month postoperatively and 13 with an old graft assessed at 1 year). All patients were studied at baseline rest and during hyperemia induced by intravenous infusion of dipyridamole, 0.56 mg/kg body weight, over 4 min. RESULTS: In the left anterior descending artery itself, systolic and diastolic peak velocities, the time average of the instantaneous spectral peak velocity (time-averaged peak velocity), vessel diameter and the calculated flow volume did not differ significantly among the four graft groups. The time-averaged peak velocity was significantly greater for new than for old arterial grafts or for new or old vein grafts (mean +/- SD 27 +/- 9 vs. 19 +/- 6, 11 +/- 5 and 12 +/- 6 cm/s, respectively, p < 0.01). However, because the diameter of new arterial grafts was significantly smaller than that of the other three grafts (2.4 +/- 0.1 vs. 2.9 +/- 0.2 [p < 0.05], 3.6 +/- 0.6 [p < 0.01] and 3.4 +/- 0.5 mm [p < 0.01], respectively), there was no difference in calculated flow volumes at rest (62 +/- 17 vs. 58 +/- 15, 61 +/- 18 and 58 +/- 19 ml/min, respectively, p = NS) between new arterial grafts and the other grafts. Although the maximal time-averaged peak velocity during hyperemia was significantly greater in new than in old arterial grafts or new or old vein grafts (47 +/- 17 vs. 40 +/- 7, 31 +/- 8 and 34 +/- 12 cm/s, respectively, p < 0.01), the flow reserve of new arterial grafts was significantly smaller than that of the other three groups (1.8 +/- 0.3 vs. 2.6 +/- 0.3, 2.8 +/- 0.5 and 3.0 +/- 0.6, respectively, p < 0.01) because the baseline time-averaged peak velocity of these new grafts was far greater than that of the other groups. CONCLUSIONS: Internal mammary artery graft flow early after operation is characterized by a higher rest velocity than that of vein graft flow. This high velocity maintains flow volume at baseline condition in compensation for the smaller diameter. Although flow reserve does not differ significantly between new and old vein grafts, that for internal mammary artery grafts is significantly reduced soon after bypass surgery. This restricted flow capacity improves late postoperatively because of an increase in diameter and a decrease in flow velocity from baseline levels.

Adult↗
PubMed1995

Somatic mutations of the PIG-A gene found in Japanese patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematologic disorder caused by deficient biosynthesis of the glycosylphosphatidylinositol (GPI) anchor. PIG-A, an X-linked gene that participates in the first step of GPI-anchor synthesis, is responsible for PNH. Abnormalities of the PIG-A gene have been demonstrated in all patients with PNH that have been studied to date. In this study, we analyzed 14 Japanese patients with PNH and identified 15 somatic mutations of PIG-A. The mutations included eight single-base changes and seven frame shift mutations. The single-base changes were two nonsense, three missense, and three splice site mutations. The frame shift mutations were four single-base deletions, two single-base insertions, and a replacement of two bases with one. They were all different, except for the same missense mutation being found in two patients. Moreover, these mutations were distributed in various regions of the gene. These results indicated that the mutations occurred at random sites and that there is no mutation hot spot in the PIG-A gene. All the mutations resulted in complete loss of function. Interestingly, the granulocytes in these patients contained variable proportions of mutant cells, suggesting that clonal expansion is not determined solely by mutations but is influenced by another factor(s).

Antigens, CD↗
PubMed1995

Comparison of antiplatelet effects of FK409, a spontaneous nitric oxide releaser, with those of TRK-100, a prostacyclin analogue.

The anti-platelet effects of FK409 ((+/-)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide) , a new spontaneous nitric oxide releaser, and TRK-100 (sodium dl-4-[(1R,2R,3aS,8bS)-1,2,3a,8b-tetra-hydro-2-hydroxy-1-[(3S ,4RS)-3-hydroxy- 4-methyl-oct-6-yen-(E)-1-enyl]-5-cyclopenta[b]benzofuranyl]butyrate), a stable prostacyclin analogue, were studied both in vivo and in vitro. FK409 and TRK-100 inhibited ADP-induced platelet aggregation in rat platelet-rich plasma at 1.0 and 0.032 microM, respectively. In a rat extracorporeal shunt model, FK409 suppressed thrombus formation dose dependently and significantly at 1.0 mg/kg and showed the maximum inhibition (52% inhibition) at 10 mg/kg. TRK-100 showed 79% inhibition of thrombus formation at 1.0 mg/kg, but not at less than 1.0 mg/kg. At the doses required for antiplatelet effects, TRK-100 decreased mean blood pressure significantly but FK409 did not alter the blood pressure. These data suggest that FK409 shows more selective activities on platelets than TRK-100 in these experiments.

Adenosine Diphosphate↗
PubMed1995

An analogue of lipid A and LPS from Rhodobacter sphaeroides inhibits neutrophil responses to LPS by blocking receptor recognition of LPS and by depleting LPS-binding protein in plasma.

When incubated with lipopolysaccharide (LPS) in the presence of plasma, neutrophils become primed for enhanced release of superoxide in response to triggering by formyl-Met-Leu-Phe (fMLP). The effect of LPS on phagocytes is inhibited by a synthetic lipid A precursor, LA-14-PP (lipid IVa) or by LPS from Rhodobacter sphaeroides (Rs). We studied the mechanisms by which LA-14-PP or Rs-LPS inhibited LPS-induced responses. When neutrophils were exposed to LA-14-PP or Rs-LPS for 3 min and then to Escherichia coli-LPS, the antagonists inhibited priming for superoxide release, and also blocked up-regulation of CD11b and adherence. This inhibition was dependent on plasma, was not overcome by higher amounts of E. coli-LPS or plasma, and was not observed at 0 degrees C, suggesting that E. coli-LPS was not able to interact with its receptor or other cellular recognition molecule in neutrophils that had been exposed to the antagonists. The alternative possibility that LA-14-PP or Rs-LPS depleted a plasma cofactor, resulting in inhibition of priming, was investigated by using LPS from Porphyromonas gingivalis (Pg) and Bordetella pertussis (Bp). These LPS primed neutrophils in a plasma-dependent and CD14-dependent manner, but were not blocked by LA-14-PP or Rs-LPS. When sub-optimal concentrations of plasma were exposed to LA-14-PP or Rs-LPS, and then mixed with Pg-LPS or Bp-LPS, followed by incubation with neutrophils, priming and up-regulation of CD11b were inhibited, and this inhibition was overcome by increasing the concentration of plasma. Binding of LPS-binding protein (LBP) in plasma to immobilized E. coli-LPS was inhibited by pre-incubation of plasma with LA-14-PP or Rs-LPS. Together with the result that treatment of plasma with anti-LBP antibody abolished the cofactor activity of plasma, these results indicated that LA-14-PP and Rs-LPS depleted LBP from plasma, resulting in inability of LPS to act on neutrophils. Thus LA-14-PP and Rs-LPS inhibited the action of LPS on neutrophils by at least two mechanisms, blocking of LPS receptor recognition and depletion of the cofactor LBP.

Acute-Phase Proteins↗
PubMed1995

Establishment of a xenogeneic chimera without GVHD in NK cell-depleted SCID mice by grafting rat fetal liver cells.

Rat lymphopoiesis did not develop when naive SCID mice were transplanted with rat fetal liver cells. However, when SCID mice were depleted of NK cells by administration of anti-murine IL-2R beta mAb before transplantation, remarkable reconstitution of both rat T and B cells was observed in these mice without any evidence of graft-versus-host disease macroscopically or histologically. T cells in these reconstituted mice proliferated well in response to Con A and third-party rat and mouse antigens, whereas no response was seen to the stimulation with either donor rat- or host mouse-type cells. When these xenogeneic chimera mice had been immunized with SRBC, these mice exhibited DTH reaction and antibody production against the homologous antigen. These results indicate that rat fetal liver cells can differentiate to functional T and B cells in the xenogeneic microenvironment of SCID mice, if host NK cells are depleted beforehand. These rat-type T cells develop within SCID thymuses and acquire tolerance to either donor F344 rat or host SCID mouse antigens.

Animals↗
PubMed1995

Rabbit skeletal muscle alpha alpha-tropomyosin expressed in baculovirus-infected insect cells possesses the authentic N-terminus structure and functions.

When expressed in E. coli, skeletal muscle alpha-tropomyosin has an unacetylated N-terminus. Unacetylated alpha-tropomyosin lacks important functions; this is non-polymerizable and has a low affinity to actin. In the present work, in order to obtain fully functional recombinant alpha-tropomyosin, rabbit skeletal muscle alpha-tropomyosin (alpha-tropomyosin BV) has been expressed in baculovirus-infected insect cells. alpha-TropomyosinBV was not distinguishable from the authentic tropomyosin, not only in functional properties but also in blocked N-terminus. To know the N-terminus structure of alpha-tropomyosinBV, the N-terminal segment six amino acids long, MDAIKK, has been specifically and efficiently removed from alpha-tropomyosinBV by use of an immobilized proteolytic enzyme system based on E. coli cell bodies which carry the ompT gene product, a proteolytic enzyme localized on the outer cell wall of E. coli. The structure of recombinant alpha-tropomyosinBV was shown to be identical to the authentic protein by electrospray mass spectrometry and protein sequencing analysis. Additionally, electrospray mass spectrometry indicated a single phosphorylation not only in alpha- but also beta-tropomyosin chains in the rabbit skeletal muscle. The differentiated susceptibilities of potential ompT cleavage sites are indicative of a non-coiled-coil conformation of the N-terminus of alpha-tropomyosin.

Amino Acid Sequence↗
PubMed1995

Expression of the intercellular adhesion molecule-1 on high endothelial venules and on non-lymphoid antigen handling cells: interdigitating cells, antigen transporting cells and follicular dendritic cells.

Intercellular adhesion molecule-1 (ICAM-1) has been implicated in the development of germinal center reactions in vitro, and the present study was undertaken to determine the distribution of ICAM-1 in active germinal centers in vivo and in murine secondary lymphoid tissues in general. Anti-ICAM-1-specific monoclonal antibodies were used in conjunction with immunohistochemistry at both the light and ultrastructural levels of resolution. Examination of cryostat sections of lymph nodes, spleens, and Peyer's patches revealed that anti-ICAM-1 distinctly labeled cells in the light zones of germinal centers, a few cells in the T cell zones (e.g. paracortex of lymph nodes), cells in the sinus floor of the subcapsular sinuses of lymph nodes, and high endothelial venules (HEV). Ultrastructural studies revealed that the cells labeling with anti-ICAM-1 in germinal centers were follicular dendritic cells (FDC) which appeared to have more ICAM-1 than any other cell type. The surfaces of well-developed, intricate, convoluted FDC processes were intensely labeled even under conditions where B cells appeared negative. Interdigitating cells (IDC) were also labeled as were certain endothelial cells in the HEV. The cells in the subcapsular sinus floor labeling with anti-ICAM-1 were the "antigen transporting cells" (ATC) that carry antigen-antibody complexes into lymph node follicles. We suspect ATC are FDC precursors which mature into FDC in the follicles. Interestingly, FDC, IDC, and ATC are 3 important accessory cells known to handle antigens in specific compartments of lymphoid tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Specific immunocytochemical localization of cathepsin E at the ruffled border membrane of active osteoclasts.

The immunocytochemical localization of cathepsin E, a non-lysosomal aspartic proteinase, was investigated in rat osteoclasts using the monospecific antibody to this protein. At the light-microscopic level, the preferential immunoreactivity for cathepsin E was found at high levels in active osteoclasts in the physiological bone modeling process. Neighboring osteoblastic cells were devoid of its immunoreactivity. At the electron-microscopic level, cathepsin E was exclusively confined to the apical plasma membrane at the ruffled border of active osteoclasts and the eroded bone surface. Cathepsin E was also concentrated in some endocytotic vacuoles of various sizes in the vicinity of the ruffled border membrane, some of which appeared to be secondary lysosomes containing the phagocytosed materials. These results strongly suggest that this enzyme is involved both in the extracellular degradation of the bone organic matrix and in the intracellular breakdown of the ingested substances in osteoclasts.

Animals↗
PubMed1995

The use of an ileostomy connector to diminish the frequency of defecation prior to ileostomy closure in patients with a pelvic pouch.

A new method for allowing stool passage into the pelvic pouch before ileostomy closure to verify the defecation state and diminish stool frequency is reported herein. This was accomplished by fitting an ileostomy connector connecting the proximal and distal openings of the diverting loop stoma. The ileostomy connector was initially in place for 6 h a day, the length of time being gradually increased until it was able to be left in for 24 h a day over a 3-month period. The calculated daily frequency of stools decreased from 24 to 6 or 7 times, and the mean daily frequency immediately after ileostomy closure was 6.5 times. Physiological study also showed an improvement, with squeeze pressure increasing from 35 cmH2O to 116 cmH2O and the maximum tolerated volume increasing from 35 ml before, to 90 ml 3 months following the use of an ileostomy connector. Thus, we conclude that an ileostomy connector may be useful to predict postoperative functional outcome and its complications, and to diminish the frequency of defecation before ileostomy closure in patients with a covering loop stoma.

Adult↗
PubMed1995

Effect of nicorandil on abnormal coronary flow reserve assessed by exercise 201Tl scintigraphy in patients with angina pectoris and nearly normal coronary arteriograms.

The purpose of the present study is to assess the effect of nicorandil, a coronary vasodilator with a mechanism of potassium channel opening, on the abnormal myocardial 201Tl perfusion evoked by exercise. Eleven patients who had a history of typical angina, positive exercise electrocardiograms, positive 201Tl scintigraphy, nearly normal coronary arteriograms, and negative coronary vasospasm underwent exercise 201Tl scintigraphies under no medication (baseline test) and administration of nicorandil (nicorandil test). 201Tl was injected at a matched workload in both tests. Nicorandil did not alter heart rate, blood pressure, or the rate-pressure product at the end of the exercise, but it significantly improved the extent score from 0.37 +/- 0.22 to 0.20 +/- 0.15 (p < 0.05) and the severity score from 33.9 +/- 32.2 to 13.5 +/- 16.4 (p < 0.05), and also significantly hastened the 201Tl mean washout rate from 30.5 +/- 14.8% to 37.4 +/- 13.1% (p < 0.05). Anginal symptoms disappeared in 3 of 5 cases and ST depression improved in 5 of 7 cases after nicorandil. We conclude that nicorandil augments coronary flow reserve, possibly due to a reduction of vasotone in the small coronary arteries.

Adult↗