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K Miyake

Publications and source records attributed to K Miyake.

At least 145 records · Page 8Linked to original sources
PubMed1998

Peptide-binding motifs of the mixed haplotype Abetaz/Aalphad major histocompatibility complex class II molecule: a restriction element for auto-reactive T cells in (NZBxNZW)F1 mice.

We previously showed that the mixed haplotype Abetaz/Aalphad major histocompatibility complex (MHC) class II molecules function as restricting element for autoreactive T-cell clones derived from autoimmune prone (NZBxNZW)F1 (B/WF1) mice. Subsequent analysis revealed that some of these Abetaz/Aalphad-restricted autoreactive T-cell clones were pathogenic upon transfer to pre-autoimmune B/WF1 mice. In this paper, we analysed the peptide-binding motif of Abetaz/Aalphad class II molecules. Amino acid-sequencing analysis of peptides eluted from purified Abetaz/Aalphad molecules revealed several sequences, including one that corresponds to murine l-plastin 588-601. Synthetic 18-mer l-plastin 588-605 peptide (SMARKIGARVYALPEDLV, as described by the amino acid single letter code) was demonstrated to bind to Abetaz/Aalphad MHC class II molecules on transfectant B lymphoma cells (TAbetaz). A competitive binding inhibition assay using truncation peptides revealed the core sequence for binding resides in 591Arg to 601Pro. Binding inhibition assay using substitution peptides, each having substitution to the other 19 residues at positions from 590Ala to 601Pro, revealed four major anchor sites 592Lys (p1), 594Gly (p3), 595Ala (p4), 597Val (p6) and one minor anchor site 600Leu (p9). Positively charged residues are not allowed at p3 and negatively charged residues are not allowed at p4 and p6. Relatively large hydrophobic residues (Leu, Ile) are not tolerated at p3 and p4. Met and Trp are not tolerated at p6. Based on these findings, the characteristics of peptides recognized by autoreactive T cells in B/WF1 mice are discussed.

Animals↗
PubMed1998

Requirement of atypical protein kinase clambda for insulin stimulation of glucose uptake but not for Akt activation in 3T3-L1 adipocytes.

Phosphoinositide (PI) 3-kinase contributes to a wide variety of biological actions, including insulin stimulation of glucose transport in adipocytes. Both Akt (protein kinase B), a serine-threonine kinase with a pleckstrin homology domain, and atypical isoforms of protein kinase C (PKCzeta and PKClambda) have been implicated as downstream effectors of PI 3-kinase. Endogenous or transfected PKClambda in 3T3-L1 adipocytes or CHO cells has now been shown to be activated by insulin in a manner sensitive to inhibitors of PI 3-kinase (wortmannin and a dominant negative mutant of PI 3-kinase). Overexpression of kinase-deficient mutants of PKClambda (lambdaKD or lambdaDeltaNKD), achieved with the use of adenovirus-mediated gene transfer, resulted in inhibition of insulin activation of PKClambda, indicating that these mutants exert dominant negative effects. Insulin-stimulated glucose uptake and translocation of the glucose transporter GLUT4 to the plasma membrane, but not growth hormone- or hyperosmolarity-induced glucose uptake, were inhibited by lambdaKD or lambdaDeltaNKD in a dose-dependent manner. The maximal inhibition of insulin-induced glucose uptake achieved by the dominant negative mutants of PKClambda was approximately 50 to 60%. These mutants did not inhibit insulin-induced activation of Akt. A PKClambda mutant that lacks the pseudosubstrate domain (lambdaDeltaPD) exhibited markedly increased kinase activity relative to that of the wild-type enzyme, and expression of lambdaDeltaPD in quiescent 3T3-L1 adipocytes resulted in the stimulation of glucose uptake and translocation of GLUT4 but not in the activation of Akt. Furthermore, overexpression of an Akt mutant in which the phosphorylation sites targeted by growth factors are replaced by alanine resulted in inhibition of insulin-induced activation of Akt but not of PKClambda. These results suggest that insulin-elicited signals that pass through PI 3-kinase subsequently diverge into at least two independent pathways, an Akt pathway and a PKClambda pathway, and that the latter pathway contributes, at least in part, to insulin stimulation of glucose uptake in 3T3-L1 adipocytes.

3T3 Cells↗
PubMed1998

[Preventive effects of diclofenac ophthalmic solution on post-cataract-surgical cystoid macular edema].

Using eyes undergoing phacoemulsification followed by implantation of a foldable acrylic intraocular lens (IOL) designed for small-incision cataract surgery, a multi-center study was performed to compare a non-steroidal ophthalmic solution (0.1% diclofenac) to a steroidal ophthalmic solution (0.1% fluorometholone) in preventing cystoid macular edema (CME) and inducing disruption of the blood-aqueous barrier determined by laser flare cellmetry. The incidence of CME, noted in 3 out of 53 eyes (5.7%) receiving diclofenac and in 29 out of 53 eyes (54.7%) receiving fluorometholone, was significantly lower in the diclofenac group. The flare in the anterior chamber was also significantly lower in the diclofenac group; when compared between eyes with and without CME, the amount of flare was significantly higher in the former group. These findings suggest that diclofenac effectively prevents CME following cataract surgery and that CME is closely related to the breakdown of the blood-aqueous barrier.

Aged↗
PubMed1997

Large plasma membrane disruptions are rapidly resealed by Ca2+-dependent vesicle-vesicle fusion events.

A microneedle puncture of the fibroblast or sea urchin egg surface rapidly evokes a localized exocytotic reaction that may be required for the rapid resealing that follows this breach in plasma membrane integrity (Steinhardt, R.A,. G. Bi, and J.M. Alderton. 1994. Science (Wash. DC). 263:390-393). How this exocytotic reaction facilitates the resealing process is unknown. We found that starfish oocytes and sea urchin eggs rapidly reseal much larger disruptions than those produced with a microneedle. When an approximately 40 by 10 microm surface patch was torn off, entry of fluorescein stachyose (FS; 1, 000 mol wt) or fluorescein dextran (FDx; 10,000 mol wt) from extracellular sea water (SW) was not detected by confocal microscopy. Moreover, only a brief (approximately 5-10 s) rise in cytosolic Ca2+ was detected at the wound site. Several lines of evidence indicate that intracellular membranes are the primary source of the membrane recruited for this massive resealing event. When we injected FS-containing SW deep into the cells, a vesicle formed immediately, entrapping within its confines most of the FS. DiI staining and EM confirmed that the barrier delimiting injected SW was a membrane bilayer. The threshold for vesicle formation was approximately 3 mM Ca2+ (SW is approximately 10 mM Ca2+). The capacity of intracellular membranes for sealing off SW was further demonstrated by extruding egg cytoplasm from a micropipet into SW. A boundary immediately formed around such cytoplasm, entrapping FDx or FS dissolved in it. This entrapment did not occur in Ca2+ -free SW (CFSW). When egg cytoplasm stratified by centrifugation was exposed to SW, only the yolk platelet-rich domain formed a membrane, suggesting that the yolk platelet is a critical element in this response and that the ER is not required. We propose that plasma membrane disruption evokes Ca2+ regulated vesicle-vesicle (including endocytic compartments but possibly excluding ER) fusion reactions. The function in resealing of this cytoplasmic fusion reaction is to form a replacement bilayer patch. This patch is added to the discontinuous surface bilayer by exocytotic fusion events.

Animals↗
PubMed1997

A critical role of Lyn and Fyn for B cell responses to CD38 ligation and interleukin 5.

CD38 ligation on mouse B cells by CS/2, an anti-mouse CD38 mAb, induced proliferation, interleukin 5 (IL-5) receptor alpha chain expression, and tyrosine phosphorylation of Bruton tyrosine kinase (Btk) from wild-type, but not from X chromosome-linked, immunodeficient mice. B cells from fyn-deficient (Fyn-/-) and lyn-deficient (Lyn-/-) mice showed an impaired response to mAb CS/2 for proliferation and IL-5 receptor alpha chain expression, and B cells from fyn/lyn double-deficient (Fyn/Lyn-/-) mice did not respond at all to mAb CS/2. The Btk activation by CD38 ligation was observed in B cells from Fyn-/- mice, and it was severely impaired in B cells from Lyn-/- and Fyn/Lyn-/- mice. CD38 expression on B cells from three mutant strains was comparable to that on control B cells. We infer from these results that both Fyn and Lyn are required and that their signals are synergistic for B cell triggering after CD38 ligation. Lyn is upstream of Btk activation in the CD38 signaling. Stimulation of B cells with IL-5 together with CD38 ligation induces not only IgM but also IgG1 secretion. Analysis of the synergistic effects of IL-5 and CD38 ligation on IgG1 secretion revealed the impaired IgG1 secretion of B cells from Lyn-/- and Fyn/Lyn-/- mice. These data imply that Lyn is involved in B cell triggering by CD38 ligation plus IL-5 for isotype switching.

ADP-ribosyl Cyclase↗
PubMed1997

Raised prostate-specific antigen in adenocarcinoma of the colon.

Serum prostate-specific antigen (PSA) values above 10 ng/ml are considered highly sensitive and specific for prostatic carcinoma in the absence of prostatic inflammation or trauma. However, in rare instances, non-prostatic malignancies have also been associated with raised serum PSA values. We have encountered a patient with increased serum PSA concentration measured by monoclonal antibody assay who had no evidence of prostatic malignant involvement, but suffered from colon cancer. Before operation for colon cancer his PSA was always over 30 ng/ml on several examinations. After total removal of colon cancer serum PSA level fell down to 1.2 ng/ml. Although immunohistochemical staining of colon cancer with monoclonal PSA antibody was not performed, some relationship between raised PSA and colon cancer is strongly suspected. Substances like serine protease which can cross-react with the PSA antibody might be produced by malignant tumour of non-prostatic origin.

Adenocarcinoma↗
PubMed1997

Failure in learning task and loss of cortical cholingergic fibers in microsphere-embolized rats.

The present study was undertaken to elucidate the pathological changes in learning and memory functions and in the metabolism of cortical cholinergic neurons following microsphere embolism in the rat. Microspheres (48 microm) were injected into the right internal carotid artery of rats. Learning and memory functions were measured 7 or more days after the embolism by active and passive avoidance, and water maze tasks. In the biochemical study, cortical acetylcholine and choline contents, and choline acetyltransferase activity were measured. Cortical acetylcholinesterase-containing fibers were quantitatively estimated in the embolized rat. The active and passive avoidance, and water maze tasks were impaired in the microsphere-embolized rat. In the histochemical study, the density of cortical acetylcholinesterase-containing fibers of the ipsilateral hemisphere of the microsphere-embolized rat was decreased, but cell density was unchanged. Furthermore, microsphere embolism decreased the cortical acetylcholine concentration and choline acetyltransferase activity and increased the choline concentration. The results suggest that microsphere embolism causes severe damage to cortical cholinergic neurons, which may be, at least in part, related to the impairment of learning and memory functions in the sustained brain ischemia.

Acetylcholine↗
PubMed1997

Transformation system for a wastewater treatment yeast, Hansenula fabianii J640: isolation of the orotidine-5'-phosphate decarboxylase gene (URA3) and uracil auxotrophic mutants.

A transformation system for Hansenula fabianii J640, a commonly used wastewater treatment yeast, was constructed. As a host cell, a uracil auxotrophic mutant designated as H. fabianii J640 u-1, which was confirmed to have a mutation at the locus of the gene for orotidine-5'-phosphate (OMP) decarboxylase (URA3), was obtained by positive selection using 5-fluoroorotic acid. A plasmid named pHFura3, which includes a 795-bp open-reading frame of the OMP decarboxylase H. fabianii, was obtained by complementation of the Escherichia coli pyrF mutant, pHFura3 could transform H. fabianii J640 u-1 by a non-homologous and frequently multicopy integration into the host genomic DNA.

Amino Acid Sequence↗
PubMed1997

Human follicular dendritic cells in vitro and follicular dendritic-cell-like cells.

Human follicular dendritic cell (FDC)-like cells (FLC) have been utilized for the in vitro analysis of germinal center reactions. However, there is no consensus whether FLC represent FDC in vitro. The purpose of the present study has therefore been to determine distinguishing features of FDC and FLC in vitro. The expression of CD40, CD54, CD49d, cytokine (gamma-IFN and IL-4)-dependent MHC-class II, and CD106 was observed to be specific for the determination of FDC in long-term culture. The cytokine-dependent emperipolesis of germinal center B cells was establised as another discriminating property for FDC in vitro. In 2 out of 72 long-term cultures of FDC, we encountered dividing cells among the non-dividing population of FDC. The dividing cells expressed accessory molecules similar to those of FDC but showed emperipolesis only for the initial few days of their growth. FDC did not enhance the CD40-dependent proliferation of germinal center B cells; in contrast, FLC augumented it. Both types of cells produced a significant amount of cytokine-dependent IL-6. Further studies are needed to determine whether FLC originate from FDC in vitro.

Cell Adhesion↗
PubMed1997

Analysis of Vbeta4 T cell receptor CDR3 repertoire in BALB/c and (NZB x NZW)F1 mice.

To examine the unique TCR repertoire in auto-immune-prone (NZB x NZW)F1 (B/WF1) mice, we analysed the Vbeta4 CDR3 region of TCRbeta chain in spleens of young (1 month old) and aged (6 month old) BALB/c and B/WF1 mice. Total RNA from spleens was used for cDNA synthesis and TCRVbeta4 PCR products were cloned and sequenced. Young B/WF1 mice showed high frequency (38.5%) of anionic amino acid residues at position beta100 in TCRVbeta4 chain compared to that (19.0%) in young BALB/c mice. Aged BALB/c mice and B/WF1 mice showed increase of frequency (38.1 and 51.9%, respectively) of anionic residues at beta100. These results indicate that Vbeta4-T cells that have anionic residues at beta100 in CDR3 region of TCRbeta chain increase with age in normal mice. Auto-immune prone mice show high frequency of anionic residues at beta100 in TCRVbeta4 chain even at the age of 1 month. These T cells may interact with cationic self-antigen(s) and might contribute to the onset and/or the progression of systemic autoimmunity in concert with other genetic elements in B/WF1 mice.

Amino Acid Sequence↗
PubMed1997

Changes in cholinergic neurons and failure in learning function after microsphere embolism-induced cerebral ischemia.

Central cholinergic neurons play an important role in learning and memory functions. The present study was undertaken to elucidate the pathological changes in learning function and acetylcholine metabolism of the cerebral cortex and hippocampus, following microsphere embolism in rats. Microspheres (48 microns) were injected into the right internal carotid artery of the rats. Learning function was determined using a passive avoidance task on the seventh day after the embolism. In the biochemical study, acetylcholine and choline contents, and choline acetyltransferase activity were measured in the cerebral cortex and hippocampus. Cortical acetylcholinesterase-containing fibers were quantitatively estimated in the embolized rat. Passive avoidance was impaired in the microsphere-embolized rat. Microsphere embolism decreased the acetylcholine concentration and choline acetyltransferase activity in the cerebral cortex and hippocampus. In the histochemical study, the length of cortical acetylcholinesterase-containing fibers was decreased, but cell density was unchanged in the ipsilateral hemisphere of the microsphere-embolized rat. The results suggest that microsphere embolism induces severe damage to cholinergic neurons, which may be related to the impairment of learning function in the ischemic brain.

Acetylcholine↗
PubMed1997

Visual outcome after management of a posteriorly dislocated lens nucleus during phacoemulsification.

PURPOSE: To evaluate the characteristics of eyes with a posteriorly dislocated lens nucleus during phacoemulsification and to assess the results of the management. SETTING: Department of Ophthalmology, Nagoya University School of Medicine, Nagoya, Japan. METHODS: Fifteen eyes (15 patients) with posteriorly dislocated lens nuclei during phacoemulsification were evaluated retrospectively. Patients ranged in age from 56 to 86 years old (mean 73.9 years +/- 9.6 [SD]). Thirteen of the 15 eyes had advanced cataract with hard nucleus before surgery Three patients developed secondary glaucoma resulting from the lens particle after nuclear dislocation. RESULTS: One dislocated lens nucleus was not removed surgically and only observed. In three patients, an attempt had been made to remove the dislocated lens nucleus at the time of cataract surgery. This caused massive choroidal hemorrhage with giant retinal tear, posterior retinal tear, and ora tear, respectively. Finally, the displaced nucleus was removed in 14 patients who had a pars plana vitrectomy at the time of cataract surgery (4 eyes) or a secondary procedure (10 eyes). In 5 eyes, liquid perfluorocarbon was used for the procedure. An intraocular lens (IOL) was successfully implanted in all eyes that were expected to have IOL implantation before surgery except in 1 eye with choroidal hemorrhage. CONCLUSION: Although the results of secondary management of displaced lens nucleus were fairly good, surgeons should take great care to avoid serious secondary complications such as retinal detachment and massive choroidal hemorrhage.

Aged↗
PubMed1997

Effects of delayed treatment with nebracetam on neurotransmitters in brain regions after microsphere embolism in rats.

1. The effects of delayed treatment with nebracetam, a novel nootropic drug, on neurotransmitters of brain regions were examined in rats with microsphere embolism-induced cerebral ischaemia. 2. Cerebral ischaemia was induced by administration of 900 microspheres (48 microns) into the internal carotid artery. The rats with stroke-like symptoms were treated p.o. with 30 mg kg-1 nebracetam twice daily. The levels of acetylcholine, dopamine, noradrenaline, 5-hydroxytryptamine (5-HT) and their metabolites in the cerebral cortex, striatum and hippocampus of animals with microsphere embolism were determined by high performance liquid chromatography (h.p.l.c.) on the 3rd and 7th days after the operation. 3. Although the microsphere embolism induced significant changes in most of the neurotransmitters and some of their metabolites in the brain regions, the delayed treatment with nebracetam partially restored only the hippocampal 5-HT and the striatal dopamine metabolite contents on the 3rd day. 4. The hippocampal in vivo 5-HT synthesis, but not the striatal dopamine synthesis, was attenuated in rats with microsphere embolism on the 3rd day, but was restored by treatment with nebracetam. In vivo striatal dopamine turnover rate of the rats with microsphere embolism was inhibited on the 3rd day irrespective of treatment with nebracetam. 5. The present study provides evidence for a possible action of nebracetam on 5-HT metabolism in the ischaemic brain.

Acetylcholine↗
PubMed1997

Molecular investigation of GB virus C infection in hemophiliacs in Japan.

RNA of a putative non-A, -B, -C, -D, or -E hepatitis virus named GB virus C (GBV-C) was detected by reverse transcription-polymerase chain reaction with primers deduced from the 5' untranslated region in 15 (24%) of 63 men with hemophilia in Japan at a frequency higher (P < .001) than that in 2 (0.6%) of 337 controls. By phylogenetic analysis, GBV-C isolates from some patients were similar in sequence, indicating infection with closely related strains, and those from certain patients resembled sequences reported from foreign countries. All patients were infected with hepatitis C virus, and genotypes that are rare in Japan were detected in 36 (57%) of them. These results indicate that patients with hemophilia in Japan would be at increased risk for infection with GBV-C and hepatitis C virus, some of which would have been transmitted via imported coagulation factor concentrates in the past.

Adolescent↗