Search PubMed⌕ Search

Biomedical subjects

T Nagano

Publications and source records attributed to T Nagano.

At least 55 records · Page 3Linked to original sources
PubMed2001

Inflammatory pseudotumor of the liver complicated with recurrent gouty arthritis.

Inflammatory pseudotumor (IPT) of the liver is a rare benign lesion of unknown etiology and is often accompanied by fever. Unexplained persistent fever unresponsive to antibiotics developed in a 70-year-old man suffering from intractable recurrent gouty arthritis. 67Ga-scintigraphy disclosed intense focal uptake in the upper abdomen. The lesion in the left lobe of the liver was an ill-defined hypodensity mass on computed tomographic scan and was enhanced on dynamic magnetic resonance imaging. The tumor was surgically removed and a diagnosis of IPT was made. Fever and arthritis resolved completely after surgery. Possible interaction between IPT of the liver and gouty arthritis was suggested.

Aged↗
PubMed2001

Role of the small GTP-binding protein rho in epithelial cell migration in the rabbit cornea.

PURPOSE: To determine the role of the small guanosine triphosphate (GTP)-binding protein Rho in the migration of corneal epithelial cells. METHODS: The presence of the Rho target proteins Rho-associated coiled coil-containing protein kinase (ROCK)-1 and ROCK-2 in rabbit cornea was examined by immunohistochemical analysis, and that of the corresponding mRNAs in rabbit corneal epithelial cells was determined by reverse transcription-polymerase chain reaction analysis. The effects of various agents on epithelial cell migration were investigated by measuring the length of the migration path in rabbit corneal blocks in culture. RESULTS: Both ROCK-1 and ROCK-2 were detected in the rabbit corneal epithelium at both protein and mRNA levels. The Rho activator lysophosphatidic acid (LPA) stimulated corneal epithelial migration in a dose-dependent manner, whereas exoenzyme C3, a Rho inhibitor, inhibited epithelial migration also in a dose-dependent manner. The stimulatory effect of LPA on corneal epithelial migration was prevented by exoenzyme C3. Both cytochalasin B, an inhibitor of actin filament assembly, and ML-7, an inhibitor of myosin light chain kinase, also prevented LPA stimulation of epithelial migration. CONCLUSIONS: These results suggest that Rho mediates corneal epithelial migration in response to external stimuli by regulating the organization of the actin cytoskeleton.

Actins↗
PubMed2001

[The usefulness of intra-operative angiography during off-pump CABG].

BACKGROUND: Recently OPCAB has become more and more common in CABG, although one problem of OPCAB like the quality of anastomosis has not been solved yet. We discussed the usefulness of intra-operative angiography during OPCAB. METHODS: During March 1997-July 2000, 55 patients underwent OPCAB (including 35 MIDCAB cases) in our institute. Graft flow and anastomosis were examined by intra-operative or immediate post-operative angiography. RESULTS: Immediate postoperative angiography was performed in 22 MIDCAB cases. In 15 cases an excellent graft flow without stenosis could be confirmed, in 7 cases the native LAD was so small, which caused a poor flow of the LITA and three cases needed additional PTCA because of anastomosis stenosis. Intra-operative angiography was done in 9 MIDCAB and 17 OPCAB. As a result, re-anastomosis was performed in one case of MIDCAB because of severe anastomosis stenosis, one case of OPCAB had confirmed poor flow because of a small LAD, but in 24 cases an excellent graft flow could be seen on time. In 2 cases OPCAB was combined with PTCA to achieve complete revascularization. CONCLUSIONS: Intra-operative angiography is a useful strategy to confirm the surgical results quickly in OPCAB (included MIDCAB). Using such a strategy, combination of OPCAB and PTCA as a new approach for complete revascularization can be performed safe and smooth.

Aged↗
PubMed2001

Stimulatory effect of pseudomonal elastase on collagen degradation by cultured keratocytes.

PURPOSE: The pathobiology of corneal ulceration induced by Pseudomonas aeruginosa was investigated by characterization of the pseudomonal pathogenic factors responsible for degradation of the collagen matrix. METHODS: Three-dimensional gels of type I collagen containing (or not) rabbit keratocytes were incubated in the presence of either culture supernatant of P. aeruginosa strain PAO1 or pseudomonal pathogenic factors (elastase, lipopolysaccharide, or exotoxin A), and the extent of collagen degradation was assessed after 24 hours by measurement of released hydroxyproline. Activation of matrix metalloproteinases (MMPs) produced by keratocytes was also examined by gelatin zymography and immunoblot analysis. RESULTS: In the absence of keratocytes, the PAO1-conditioned medium increased the extent of collagen degradation. The conditioned medium also promoted keratocyte-mediated collagen degradation. Of the pseudomonal pathogenic factors examined, only elastase degraded collagen directly as well as stimulated keratocyte-mediated collagen degradation. Culture supernatant of elastase-deficient P. aeruginosa (lasR or lasB) mutants had no effect on collagen degradation in the absence or presence of keratocytes. Elastase also induced the conversion of the inactive precursors of MMP-1, -2, -3, and -9 produced by keratocytes to the active forms of the enzymes. CONCLUSIONS: These results suggest that pseudomonal elastase both degrades type I collagen directly and promotes collagen degradation mediated by keratocytes, the latter effect being likely attributable, at least in part, to the activation of proMMPS:

ADP Ribose Transferases↗
PubMed2000

Determination and bioimaging method for nitric oxide in biological specimens by diaminofluorescein fluorometry.

A simple and sensitive assay and a cellular bioimaging method for nitric oxide (NO) were developed using a novel diaminofluorescein DAF-FM and its diacetate. DAF-FM is converted via an NO-specific mechanism to an intensely fluorescent triazole derivative. For the measurement of NO, the triazole derivative of DAF-FM was determined by reversed-phase high-performance liquid chromatography with fluorescence detection. In the presence of 1 microM DAF-FM, the concentrations of NOR-1, an NO donor, in the range of 2-200 nM were linearly related to the fluorescence intensity. This sensitive NO assay enabled us to detect the spontaneous and substance P-induced NO release from isolated porcine coronary arteries, both of which were dependent entirely on the NO synthase activity in vascular endothelial cells. We also obtained fluorescence images of cultured smooth muscle cells of the rat urinary bladder after loading with DAF-FM diacetate. In the cells pretreated with cytokines, the fluorescence intensity increased with time after DAF-FM loading. This increase in the fluorescence intensity was blocked by prior treatment of the muscle cells with an NO synthase inhibitor, N(G)-nitro-l-arginine methyl ester. Therefore, the present novel diaminofluorescein fluorometry should be useful not only for sensitive NO assay, but also for NO imaging in a variety of biological specimens.

Animals↗
PubMed2000

Considerable time from the onset of plaque rupture and/or thrombi until the onset of acute myocardial infarction in humans: coronary angiographic findings within 1 week before the onset of infarction.

BACKGROUND: It has been thought that the thrombi and bleeding in plaques that occur after plaque rupture or endothelial damage from vessels with mild stenosis suddenly occlude the lumen and cause acute myocardial infarction (AMI). However, our hypothesis is that thrombi and bleeding may not suddenly occlude the lumen. METHODS AND RESULTS: The study group consisted of 20 patients who had coronary angiograms performed within 1 week (3+/-3 days) before AMI and 20 control patients who had coronary angiograms performed 6 to 18 months (282+/-49 days) before AMI. The features of infarct-related coronary segments (IRCS) at 3 days before AMI were the presence of a significant stenosis of >50% (95% in incidence and 71+/-12% diameter stenosis) and Ambrose's type II eccentric lesions (plus multiple irregularities), an indicator of plaque rupture and/or thrombi (60% [70%]), and the features at 1 year before AMI were mild stenosis of <50% (95% incidence and 30+/-18% diameter stenosis) with rare Ambrose's type II eccentric lesions (plus multiple irregularities) (10% [10%]). The same relation was observed in each of the 4 subgroups with Q-wave infarction, non-Q-wave infarction, preceding effort angina within 1 month before AMI, and no preceding effort angina. CONCLUSIONS: The appearance of marked progression and Ambrose's type II eccentric lesion on coronary angiograms 3 days before AMI suggests the presence of a considerable time from the onset of plaque rupture and/or thrombi until the onset of AMI. These features may be predictors of AMI. The concept provides new insight into the mechanism and prevention of human AMIs.

Acute Disease↗
PubMed2000

Development of a time-resolved fluorometric detection system using diffusion-enhanced energy transfer

A novel detection system using both emission energy transfer and time-resolved fluorometry (TRF) was developed, with a europium chelate as the energy donor and a novel fluorophore SNR1, excitable with long-wavelength light corresponding to europium emission, as the energy acceptor. When the donor and acceptor molecules were mixed in solution, energy transfer was observed without direct attachment of the donor and the acceptor, via a diffusion-enhanced energy-transfer mechanism. Thus, the acceptor emission can be detected as a long-lifetime fluorescence in TRF. When the fluorescence properties of the acceptor molecule are changed by interaction with an enzyme or other bioactive molecule, the change can be detected as a long-lived sensitized emission. If we develop or select suitable acceptor molecules, this simple and convenient system should be applicable to a wide variety of bioactive molecules. Since it is based on TRF, it can be used for high-resolution assay.

Journal Article↗
PubMed2000

Homeobox gene Hex is essential for onset of mouse embryonic liver development and differentiation of the monocyte lineage.

Disruption of the mouse Hex gene resulted in embryonic lethality around embryonic age (E) 10.5, due to no substantial liver formation. Expression of albumin was detectable in heterozygous (Hex(+/-)) but not in homozygous (Hex(-/-)) [corrected] embryos at E8.5. Instead of liver bud formation at E9.5, a liver-like capsule structure was observed in Hex(-/-) [corrected] embryos. In Hex(-/-) [corrected] mutant liver, we found no hepatocytes but no signs of apoptotic cell death in the area. Expression of transcription factors involved in hepatocyte differentiation, hepatocyte nuclear factor (Hnf)3beta, Hnf6, Hnf4alpha and Hnf1alpha, were restricted to the capsule and internal matrix-like structure in the mutant liver and expression of a subset of these factors were reduced. Hematopoiesis of monocytes was impaired in mutant embryos while erythroid lineage was unaffected. These results indicate that Hex plays an essential role in progenitor cells which commit to the hepatic endoderm and in the hematopoietic differentiation of the monocyte lineage.

Albumins↗
PubMed2000

The transport mechanism of metallothionein is different from that of classical NLS-bearing protein.

A nuclear localization signal (NLS) has been detected in several nuclear proteins. Classical NLS-mediated nuclear pore targeting is performed by using the cytosolic factors, importin alpha and importin beta, whereas nuclear translocation requires the small GTPase, Ran. In the present study, we demonstrated that nuclear localization of metallothionein (MT) differs from that of classical NLS-mediated substrates. In digitonin-permeabilized BALB/c3T3 cells, biotinylated MT was localized in the nucleus in the presence of ATP and erythrocyte cytosol in the same manner as for SV40 large T NLS-conjugated allophycocyanin (APC-NLS). Under ATP-free conditions, nuclear rim-binding was observed in both transport substrates. Rim-binding of labeled MT was competitively inhibited by the addition of an excess amount of unlabeled MT. Different elution profiles were observed for the localization-promoting activities of MT in the cytosol compared to those of APC-NLS. Furthermore, nuclear localization of MT was determined to be a wheat germ agglutinin-insensitive, GTPgammaS-sensitive, and anti-Ran antibody-sensitive process. Green fluorescent protein-metallothionein (GFP-MT) fusion protein was also localized in the nucleus in the stable transformant of CHL-IU cells. These results strongly suggest that the targeting by MT of the nuclear pore is mediated by cytosolic factor(s) other than importins and that MT requires Ran for its nuclear localization.

3T3 Cells↗
PubMed2000

Precursor genes of future pandemic influenza viruses are perpetuated in ducks nesting in Siberia.

Influenza A viruses of different subtypes were isolated from fecal samples of ducks in their nesting areas in Siberia in summer from 1996 to 1998. Phylogenetic analysis of the NP genes of the isolates in Siberia and those in Hokkaido, Japan on their flyway of migration from Siberia to the south in autumn revealed that they belong to the Eurasian lineage of avian influenza viruses. It is noted that the genes of the isolates in Siberia are closely related to those of H5N1 influenza virus strains isolated from chickens and humans in Hong Kong in 1997 as well as to those of isolates from domestic birds in southern China. The results indicate that influenza viruses perpetuated in ducks nesting in Siberia should have contributed genes in the emergence of the H5N1 virus in Hong Kong. Vaccine prepared from avirulent A/duck/Hokkaido/4/96 (H5N3) influenza virus was potent enough to protect mice from challenge with lethal dose of the pathogenic H5N1 virus [19]. Intensive surveillance study of aquatic birds especially in Siberia is, therefore, stressed to provide information on the future pandemic influenza virus strains and for vaccine preparation.

Animals↗
PubMed2000

A new thioether-ligated iron porphyrin as a model of a protonated form of P450 active site.

Thioether-ligated iron porphyrin (complex 1) was synthesized as a model of the protonated form of P450 to explore the possible involvement of the protonated form in the catalytic cycle, and ether-ligated iron porphyrin (complex 2) was also synthesized for comparison. The thioether and ether ligands enhanced heterolytic O-O bond cleavage of peroxy acid-iron porphyrin complex even in highly hydrophobic media without the assistance of acid or base, using mCPPAA as an oxidant. Competitive oxidation of cyclooctane/cyclooctene catalyzed by iron porphyrins showed that complexes 1 and 2 are less effective than heme thiolate (P450 and a synthetic heme thiolate (SR complex)) in oxidizing alkane. The possibility that thiol-ligated heme, which is a protonated form of heme thiolate, is not involved in the active intermediate structure of P450 is indicated by this result. This is the first report concerning the oxidizing ability of a thioether-ligated iron porphyrin.

Binding Sites↗
PubMed2000

Remarkable axial thiolate ligand effect on the oxidation of hydrocarbons by active intermediate of iron porphyrin and cytochrome P450.

In order to examine the reactivity of active intermediate derived form iron porphyrins, competitive oxidations of alkane and alkene were carried out. It has been proposed that the first step of alkane hydroxylation is H atom abstraction and that of alkene is one-electron transfer. Therefore, it is expected that alkene-alkane competitive oxidation can be used as a probe for discrimination of differences in chemical properties among active species. Cytochrome P450 and SR complex, which is a stable thiolate-ligated iron porphyrin, mediated the oxidation of alkane much more preferentially than iron porphyrin coordinated by imidazole or chloride. These results indicate that thiolate coordination alters the reactivity of the two-electron-oxidized intermediate in a manner that is much more favorable to alkane hydroxylation than the case of chloride or imidazole coordination.

Alkanes↗
PubMed2000

Dorsal induction from dorsal vegetal cells in Xenopus occurs after mid-blastula transition.

We performed some experiments to investigate the temporal and spatial details of the dorsal induction exerted by dorsal vegetal cells in Xenopus embryo. Two dorsal vegetal cells (D1 cells) were transplanted into the ventral vegetal region of a recipient at the 32-cell stage. At various times after transplantation, the ventral animal-equatorial part was explanted and cultured. The explants isolated 5.5 h after transplantation (time 5.5) elongated and formed somites. In RT-PCR analysis, the expression of dorsal gene, chordin was activated in the explants isolated after time 4.0 (about the 4000-cell stage which corresponds to the mid blastula transition (MBT)) at control stage 10. In another series of experiments, ventral animal-equatorial and dorsal vegetal parts were isolated from the 4000-cell stage embryos and they were combined for 2.0-2.5 h. These ventral animal-equatorial explants elongated and formed somites. The chordin expression was also observed in the explants. But the 32- and 256-cell stage dorsal vegetal cells failed to exert the dorsalizing activity within the 2.0-2.5 h of the conjugation. These results suggest that 2 h contact after MBT is necessary and sufficient for the dorsal induction from the dorsal vegetal cells and it occurs as a result of the zygotic gene expression. Consistent with this idea, the zygotic dorsal genes, siamois and chordin were expressed on the upper regions of the transplanted D1 descendants at stage 10. Furthermore, this region began to gastrulate when the D1 cell was transplanted with upside-down orientation. Our data indicate that the upper region of the D1 descendants by itself act as the Spemann organizer rather than the Nieuwkoop center.

Animals↗
PubMed2000

Expression of perforin and Fas ligand mRNA in the liver of viral hepatitis.

Cytotoxic T lymphocytes (CTLs) play an important role in the pathogenesis of viral hepatitis. We studied the expression of mRNAs of perforin and Fas ligand (Fas-L) in biopsy specimens from chronic hepatitis B (CHB) (15 cases) and hepatitis C (CHC) patients (13 cases). Both perforin and Fas-L mRNAs were detected in all cases of both CHB and CHC. No messages were detected in the control livers from two cases of fatty liver, a case of Gilbert's syndrome, and a case of Dubin-Johnson syndrome. Semiquantitative analysis revealed a positive correlation between the intensity of perforin and Fas-L mRNAs in both CHB and CHC. In CHB, the intensity of both perforin and Fas-L mRNAs showed a positive correlation with the histological activity and serum alanine aminotransferase level, while the correlation was not apparent in CHC. These results suggest that both perforin and Fas/Fas-L systems are involved in the pathogenesis of liver cell injury of CHB and CHC.

Adult↗
PubMed2000

A2-Pancortins (Pancortin-3 and -4) are the dominant pancortins during neocortical development.

We have identified a novel mouse gene named pancortin that is expressed dominantly in the mature cerebral cortex. This gene produces four different species of proteins, Pancortin-1-4, sharing a common region in the middle of their structure with two variations at the N-terminal (A1 or A2 part) and C-terminal (C1 or C2 part) sides, respectively. In the present study, we showed that expression of mRNAs for A2-Pancortins (Pancortin species that contain the A2 part, i.e., Pancortin-3 and -4) is more dominant than that of mRNAs for A1-Pancortins (Pancortin species that contain the A1 part, i.e., Pancortin-1 and -2) in the prenatal mouse cerebral neocortex. Using western blot analysis, we found that substantial amounts of both A2-Pancortins were present in the prenatal cerebral neocortex and P19 cells after inducing neuronal differentiation. A2-Pancortins were still present in the cerebral neocortex of the adult, although their mRNAs were hardly detected. In contrast, the amount of A1-Pancortins did not increase after the third postnatal week in spite of their intense gene expression. Furthermore, we showed that recombinant Pancortin-3, one of the A2-Pancortins, was a secreted protein, in contrast to Pancortin-1 (one of the A1-Pancortins). These results suggest that A2-Pancortins are extracellular proteins essential for neuronal differentiation and that their molecular behavior is distinct from that of A1-Pancortins.

Alkaline Phosphatase↗
PubMed2000

Molecular characterization of a novel gamma-glutamyl transpeptidase homologue found in rat brain.

A cDNA clone for a novel homologue to gamma-glutamyl transpeptidase (gamma-GTP), termed GTPH, was isolated from a rat brain expression cDNA library using antisera against total brain synaptosomal fractions. The cloned GTPH consists of 641 amino acid residues (78 kDa) and exhibits structural similarity with a conventional type of gamma-GTP that is predominantly expressed in the liver: They share significant amino acid homology (33% identity, 73% similarity) spanning over the entire sequence. RNA analyses revealed that GTPH mRNA expression is found only in the nervous system, including all brain regions, eyes and peripheral ganglia, and increases during development. Endogenous GTPH protein is a membrane-bound glycoenzyme and migrates as 90-100 kDa in polyacrylamide gels. Taken together, GTPH is a novel form of a gamma-GTP-like molecule expressed exclusively in the nervous system.

Amino Acid Sequence↗