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K Furuya

Publications and source records attributed to K Furuya.

At least 37 records · Page 2Linked to original sources
PubMed2001

High-angle annular dark-field STEM observation of Xe nanocrystals embedded in Al.

High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) observation of Xe precipitates embedded in crystalline membranes has been made using electron probes of atomic dimensions and HAADF-STEM images of Xe precipitates qualitatively different from conventional TEM observation results have been obtained. Multislice-based HAADF-STEM simulation has been made and it has been revealed that the intensity of images of Xe atoms at positions displaced from Al matrix columns decreases rapidly as the thickness increases. Even in a thin specimen, the off-site Xe atoms of the precipitate at deep locations, were not observable. Therefore, different images are expected for specimens of different thicknesses or depths of these precipitates. These results indicate that the observation of precipitates in crystalline membranes requires some care.

Journal Article↗
PubMed2001

Mrc1 transduces signals of DNA replication stress to activate Rad53.

Cells experiencing DNA replication stress activate a response pathway that delays entry into mitosis and promotes DNA repair and completion of DNA replication. The protein kinases ScRad53 and SpCds1 (in baker's and fission yeast, respectively) are central to this pathway. We describe a conserved protein Mrc1, mediator of the replication checkpoint, required for activation of ScRad53 and SpCds1 during replication stress. mrc1 mutants are sensitive to hydroxyurea and have a checkpoint defect similar to rad53 and cds1 mutants. Mrc1 may be the replicative counterpart of Rad9 and Crb2, which are required for activating ScRad53 and Chk1 in response to DNA damage.

Amino Acid Sequence↗
PubMed2001

The ACE gene polymorphism and cough threshold for capsaicin after cilazapril usage.

Persistent dry cough is an occasional but clinically important adverse reaction to angiotensin I-converting enzyme (ACE) inhibitors (ACEI). Its reported incidence is variable, and why cough occurs in only certain individuals has been unclear. An insertion/deletion (I/D) polymorphism of the ACE gene is associated with serum ACE activity. We have previously shown that susceptibility to cough induced by ACEI is associated with this polymorphism such that patients with genotype II are more susceptible to cough than patients with other genotypes. In order to confirm and extend our previous observation, we conducted a randomized, placebo-controlled, double-blind, cross-over study in 10 healthy volunteers with genotype II and 10 with genotype DD. The cough threshold was determined by the concentration of inhaled capsaicin causing two or more coughs. After the usage of an ACEI, cilazapril, for 4 weeks, changes in the cough threshold in subjects with genotype II [before: 6.6+/-3.7 nM (mean+/-SD); after: 5.0+/-4.6 nM] significantly differed from those in subjects with genotype DD (before: 9.0+/-9.4 nM; after: 9.3+/-9.1 nM). Skin responses to intradermal bradykinin, which is a substrate of ACE and tussigenic, were significantly increased in subjects with genotype II (before: 1.6+/-0.6 vs. after: 2.6+/-0.5 cm2, P<0.05) but not in subjects with genotype DD (before: 1.4+/-0.5 vs. after: 1.6+/-0.6 cm2, n.s.) after usage of cilazapril. By contrast, skin responses to intradermal substance P did not change in subjects with either genotype. These findings provide further evidence of a link between ACEI-induced cough and I/D polymorphism of the ACE gene and suggest that ACEIs induce cough by modulating the tissue level of bradykinin.

Adult↗
PubMed2001

New scheme for calculation of annular dark-field STEM image including both elastically diffracted and TDS waves.

A new scheme of calculation of high-angle annular dark-field STEM image, capable of including both elastically diffracted and thermal diffuse scattering waves, has been presented by a combination of Pennycook's and Nakamura's methods. The new scheme has been demonstrated for image simulations of Si(011) as functions of thickness, defocus values and detector angles. In the present method, the TDS electron intensities are treated in the same way as in Pennycook's method, having a clear physical picture of its origin and reflecting the atom configuration in the systems. For the case of Si(011), it has been confirmed that at the detector angle of 60 to 160 mrad, which is usually applied, the image becomes highly incoherent, and even the image formed only from SOLZ beams becomes incoherent at the detector angle. At a low detector angle, however, the image has coherent features indicating the necessity of a simulation for individual systems.

Journal Article↗
PubMed2001

High-resolution transmission electron microscopy observation of the cross-sectional structure of reconstructed silicon (5,5,12) surface.

The cross-sectional reconstructed structure of Si (5,5,12) surface was, for the first time, observed using ultrahigh vacuum high-resolution transmission electron microscopy (UHV-HRTEM) profile view method. In the high-index region, two units of the (337) surface combine with one units of the (225) surface to complete one unit cell of (5,5,12) surface. The (337) unit at one side of the (225) unit is distinctly different from that at another side of (225) unit. The observed HRTEM images do not agree with the previous structural models of the (5,5,12) surface. We propose a new structure model of this surface using a TEM image simulation. Our model is agreement with the previously reported scanning tunnelling microscope images.

Letter↗
PubMed2001

Cell permeable exogenous ceramide reduces infarct size in spontaneously hypertensive rats supporting in vitro studies that have implicated ceramide in induction of tolerance to ischemia.

Previous work in primary cell culture has shown that TNF-alpha and ceramide are involved in the signaling that induces tolerance to brain ischemia (Ginis et al., 1999; Liu et al., 2000). To validate the in vitro studies, the authors administered cell permeable analogs of ceramides intracisternally or intravenously to examine their effect on neuroprotection after focal cerebral ischemia. Permanent middle cerebral artery occlusion (MCAO) was performed in spontaneously hypertensive rats. Infarct volumes were assessed at 24 hours after surgery. D-erythro-N-acetylsphingosine (C2-ceramide) or its vehicle was infused intracisternally for 1 hour before MCAO. In a second set of studies, D-erythro-N-octanoylsphingosine (C8-ceramide) or its vehicle was injected intravenously 48 or 24 hours before MCAO to mimic preconditioning (PC) and was also injected 5 minutes after MCAO. C2-ceramide infusion significantly reduced infarct volumes by approximately 14% (P < 0.05). C8-ceramide injection reduced infarct volumes approximately 17% compared with controls. This effect was constant and significant compared with controls over the time periods examined (P < 0.01). This work supports findings in primary brain cell cultures that implicate ceramide as a downstream signal that is proximate to development of tolerance to brain ischemia. Because the degree of protection represents approximately 50% of the maximal infarct reduction observed in this model, there are probably additional signaling pathways that subserve tolerance.

Animals↗
PubMed2001

Brain vessels normally undergo cyclic activation and inactivation: evidence from tumor necrosis factor-alpha, heme oxygenase-1, and manganese superoxide dismutase immunostaining of vessels and perivascular brain cells.

Studies of vascular biology during the past decade have identified an expanding list of agonists and antagonists that regulate local hemostasis, inflammation, and reactivity in blood vessels. Interactions at the blood-endothelial interface are intricate and complex and have been postulated to play a role in the initiation of stroke and the progression of brain injury during early hours of ischemia, particularly in conjunction with reperfusion injury (Hallenbeck, 1996). In the current study of normal and activated vessels in rat brain, immunoreactive tumor necrosis factor-alpha (TNF-alpha), heme oxygenase-1 (HO-1), and manganese superoxide dismutase (MnSOD) exhibit concentric perivascular rings involving vessel wall and surrounding parenchyma that appear to coincide with one another in serial sections. The ring patterns suggest periodic radial expansion of these molecules released through a process of cyclic activation and inactivation of brain vessel segments. In this process, the rings appear randomly scattered instead of affecting all vessels within a high power field (HPF) synchronously. The average number of vessels per HPF (mean +/- SD) with perivascular cuffs of immunoreactive MnSOD increased from 51 +/- 28 in Wistar, 72 +/- 46 in Wistar-Kyoto, and 84 +/- 30 in Sprague Dawley rats (no spontaneous strokes) to 184 +/- 72 in spontaneously hypertensive stroke-prone rats (spontaneous strokes). Perivascular immunoreactive cuffs are also increased in spontaneously hypertensive rats by induction of cytokine expression by lipopolysaccharide (64 +/- 15 vs. 131 +/- 32 /HPF). The patterns of TNF-alpha, HO-1, and MnSOD in naïve animals are interpreted to indicate that focal hemostatic balance normally fluctuates in brain vessels and influences surrounding parenchymal cells. Perivascular immunoreactive cuffs representing this process are more frequent in animals with lipopolysaccharide-induced endothelial activation or genetic stroke proneness.

Aldehydes↗
PubMed2001

A case of pedunculated malignant melanoma of the vaginal mucosa.

We report an 84-year-old Japanese woman who presented with a pedunculated malignant melanoma of the vaginal mucosa. Mucosal melanoma is believed to be more common in Japan than other countries, but such tumors of the vulvovaginal region are quite unusual. In our patient, three tumors were connected by a narrow pedicle. Three black tumors measuring 5-10 mm in diameter with a common pedicle were seen on the vaginal mucosa at five o'clock from the cervix. The tumors were hanging from the narrow pedicle. On histologic examination, they were diagnosed as malignant melanoma. Resection was done with a distal margin of 3 cm from the tumors and a margin of 1 cm from the cervix. The patient has had no evidence of local recurrence or distant metastasis. In our patient, the three main tumors had a common pedicle, which seems to be a unique finding. Since pedunculated malignant melanomas are rare, making a clinical diagnosis is difficult. Although pedunculated melanomas are recognized as having a high malignant potential because these lesions are generally thick, a relatively good outcome is sometimes reported. In our patient, there was no tumor infiltration into the dermis of the pedicle, and this may be one reason for the good outcome at present. There has been no previous report of a mucosal melanoma consisting of three tumors like those in the present patient.

Aged↗
PubMed2001

Serum angiotensin I-converting enzyme is reduced in Crohn's disease and ulcerative colitis irrespective of genotype.

OBJECTIVES: Crohn's disease (CD) is recognized to be a vascular endothelial-associated disease. Angiotensin I-converting enzyme (ACE) exists mainly in endothelial cells. There are some reports on serum ACE levels in patients with CD, but the ACE level is still controversial. Recently, genetic control of serum ACE levels by ACE gene polymorphisms (classified as II, ID, and DD) has been suggested. Although we must consider such polymorphisms to elucidate ACE levels in patients with CD, there is no report about this. METHODS: We studied 341 healthy controls (male/female = 178/162), 39 patients with CD (31/8), 43 patients with ulcerative colitis (UC) (22/21) and 19 patients with infectious enterocolitis (8/11). The polymorphism in intron 16 of the ACE gene was examined by PCR. Serum ACE levels were measured by the method of Kasahara. RESULTS: Serum ACE levels in patients with CD and UC were significantly lower than in healthy controls, irrespective of the genotype of ACE (genotype II: CD 7.0+/-2.5 [mean +/- SD], UC 7.1+/-3.3, controls 11.8+/-2.9, genotype ID: CD 9.7+/-4.1, UC 11.4+/-4.6, controls 15.2+/-3.6, genotype DD: CD 13.9+/-5.8, UC 10.7+/-3.6, controls 19.3+/-3.9 IU/L, controls vs CD, UC; p < 0.01, 0.05). However, there was no significant difference in serum ACE levels between CD and UC. CONCLUSIONS: Considering ACE gene polymorphism, serum ACE levels in patients with inflammatory bowel disease are lower than in controls. Serum ACE levels reflect a part of the pathogenesis of inflammatory bowel disease.

Adult↗
PubMed2001

Examination of several potential mechanisms for the negative outcome in a clinical stroke trial of enlimomab, a murine anti-human intercellular adhesion molecule-1 antibody: a bedside-to-bench study.

BACKGROUND AND PURPOSE: Enlimomab, a murine monoclonal anti-human intercellular adhesion molecule (ICAM)-1 antibody, had a negative outcome in a multicenter acute-stroke trial. We did a bedside-to-bench study in standardized rat stroke models to explore mechanisms for these untoward results. METHODS: After focal brain ischemia in Wistar rats and spontaneously hypertensive rats (SHR), we administered murine anti-rat ICAM-1 antibody (1A29), subclass-matched murine immunoglobulin (IgG1), or vehicle intravenously. To examine whether rat anti-mouse antibodies were generated against the mouse protein and whether these were deleterious, we sensitized Wistar rats with 1A29 or vehicle 7 days before surgery. Infarct volume, tissue myeloperoxidase activity, neutrophil CD11b expression, and microvascular E-selectin, P-selectin, and ICAM-1 expression were examined 48 hours after surgery. Complement activation was serially assessed for 2 hours after a single injection of either 1A29 or vehicle. RESULTS: 1A29 treatment did not significantly reduce infarct size in either strain. 1A29 sensitization augmented infarct size and generated rat anti-mouse antibodies. Although 1A29 inhibited neutrophil trafficking shown by reduction in brain myeloperoxidase activity, circulating neutrophils were activated and displayed CD11b upregulation. Complement was activated in 1A29-sensitized Wistar rats and 1A29-treated SHR. E-selectin (SHR), endothelial P-selectin (Wistar and SHR), and ICAM-1 (SHR) were upregulated in animals treated with 1A29. CONCLUSIONS: Administration to rats of a murine antibody preparation against ICAM-1, 1A29, elicits the production of host antibodies against the protein, activation of circulating neutrophils, complement activation, and sustained microvascular activation. These observations provide several possible mechanisms for central nervous system-related clinical deterioration that occurred when Enlimomab was given in acute ischemic stroke.

Animals↗
PubMed2001

Isolation of Encephalitozoon cuniculi using primary tissue culture techniques from a rabbit in a colony showing encephalitozoonosis.

Encephalitozoon spores were isolated in a primary tissue culture of the kidneys from an encephalitozoonosis-suspected rabbit in a municipal zoo in Hokkaido. The isolated spores were morphologically characteristic of microsporidial ones in chromotrope stain, and proven to be E. cuniculi by a polymerase chain reaction (PCR) with a species-specific primer set and by direct DNA sequencing of the PCR products.

Animals↗
PubMed2001

Osteopontin deficiency reduces experimental tumor cell metastasis to bone and soft tissues.

Osteopontin has been implicated in the metastasis of tumors, and human tumors with high metastatic activity often express osteopontin at high levels. Osteopontin contains an arginine-glycine-aspartate (RGD) motif that is recognized by integrin family members to promote various cell activities including attachment to substrate and it is abundant in bone, to which certain tumors preferentially metastasize. Therefore, we investigated the role of osteopontin in the experimental metastasis of tumor cells using recently established osteopontin-deficient mice. B16 melanoma cells, which produce little osteopontin, were injected into the left ventricle of osteopontin-deficient mice or wild-type mice. Animals were killed 2 weeks after injection. The number of tumors was reduced in the bones of osteopontin-deficient mice compared with the bones in wild-type mice. The number of tumors in the adrenal gland also was reduced. To investigate the osteopontin effect on metastases via a different route, we injected B16 melanoma cells into the femoral vein. Through this route, the number of lung tumors formed was higher than in the intracardiac route and was again less in osteopontin-deficient mice compared with wild-type mice. In conclusion, in an experimental metastasis assay, the number of tumors found in bone (after intracardiac injection) and lung (after left femoral vein injection) was significantly reduced in osteopontin-deficient mice compared with wild-type mice. Tumor numbers in other organs examined were small and not significantly different in the two situations.

Animals↗
PubMed2001

Reactive blue 2 induces calcium oscillations in HeLa cells.

Reactive Blue 2 (RB), which is used as an ATP receptor antagonist, induced Ca(2+) oscillations in HeLa cells. RB-induced Ca(2+) oscillations were abolished in Ca(2+)-free solution. RB, however, did not affect Ca(2+) influx measured by Mn(2+) quenching. The PLC cascade and intracellular Ca(2+) release were involved as U73122 and thapsigargin inhibited RB-induced Ca(2+) oscillations. RB enhanced a Ca(2+) response to histamine that is linked to the PLC cascade. RB may activate the PLC cascade in an extracellular Ca(2+)-dependent manner and induce Ca(2+) oscillations.

Calcium Channels↗
PubMed2000

Overexpression of Cas-interacting zinc finger protein (CIZ) suppresses proliferation and enhances expression of type I collagen gene in osteoblast-like MC3T3E1 cells.

Osteoblasts are the cells which form bone under the regulation not only by hormones and cytokines but also by ECM molecules via their attachment. To obtain insights into the role of intracellular signaling molecules operating to mediate the attachment-related regulation of osteoblastic functions, we investigated in osteoblast-like MC3T3E1 cells the effects of the overexpression of CIZ, a novel signaling protein which interacts with p130Cas. In MC3T3E1 cells, CIZ mRNA is expressed constitutively. Endogenous CIZ was localized in the MC3T3E1 cells with relatively high levels of accumulation at the attachment sites when the cells were cultured on fibronectin, collagen, or BSA. CIZ overexpression increased the number of adhesion plaques and reduced proliferation of the cells compared to that of control cells transfected with an empty vector. Furthermore, CIZ overexpression enhanced type I collagen mRNA expression, the most abundant constituent of bone matrix and a major product of osteoblasts. Analysis of the promoter region of type I collagen gene identified the presence of a consensus CIZ-binding sequence, which indeed conferred responsiveness to CIZ overexpression to a heterologous promoter. These data indicate that CIZ acts as a novel regulatory molecule in controlling osteoblastic function.

Animals↗
PubMed2000

Characterization of fission yeast cohesin: essential anaphase proteolysis of Rad21 phosphorylated in the S phase.

Cohesin complex acts in the formation and maintenance of sister chromatid cohesion during and after S phase. Budding yeast Scc1p/Mcd1p, an essential subunit, is cleaved and dissociates from chromosomes in anaphase, leading to sister chromatid separation. Most cohesin in higher eukaryotes, in contrast, is dissociated from chromosomes well before anaphase. The universal role of cohesin during anaphase thus remains to be determined. We report here initial characterization of four putative cohesin subunits, Psm1, Psm3, Rad21, and Psc3, in fission yeast. They are essential for sister chromatid cohesion. Immunoprecipitation demonstrates stable complex formation of Rad21 with Psm1 and Psm3 but not with Psc3. Chromatin immunoprecipitation shows that cohesin subunits are enriched in broad centromere regions and that the level of centromere-associated Rad21 did not change from metaphase to anaphase, very different from budding yeast. In contrast, Rad21 containing similar cleavage sites to those of Scc1p/Mcd1p is cleaved specifically in anaphase. This cleavage is essential, although the amount of cleaved product is very small (<5%). Mis4, another sister chromatid cohesion protein, plays an essential role for loading Rad21 on chromatin. A simple model is presented to explain the specific behavior of fission yeast cohesin and why only a tiny fraction of Rad21 is sufficient to be cleaved for normal anaphase.

Anaphase↗
PubMed2000

Cockroach diuretic hormones: characterization of a calcitonin-like peptide in insects.

Insect diuretic hormones are crucial for control of water balance. We isolated from the cockroach Diploptera punctata two diuretic hormones (DH), Dippu-DH(31) and Dippu-DH(46), which increase cAMP production and fluid secretion in Malpighian tubules of several insect species. Dippu-DH(31) and -DH(46) contain 31 and 46 amino acids, respectively. Dippu-DH(46) belongs to the corticotropin-releasing factor (CRF)-like insect DH family, whereas Dippu-DH(31) has little sequence similarity to the CRF-like DH, but is similar to the calcitonin family. Dippu-DH(46) and -DH(31) have synergistic effects in D. punctata but have only additive effects in Locusta migratoria. Dippu-DH(31) represents a distinct type of insect DH with actions that differ from those of previously identified insect peptides with diuretic activity.

Amino Acid Sequence↗