Biomedical subjects

Y Yasuda

Publications and source records attributed to Y Yasuda.

At least 73 records · Page 4Linked to original sources

PubMed2000

Self-assembling photosynthetic reaction centers on electrodes for current generation.

Photosynthetic reaction centers (RCs) made from photosynthetic organisms can be used in solar batteries because their molecules cause light-induced charge separation. We present a simple immobilization system of the intact RCs from Rhodobacter sphaeroides on an electrode that uses nickel ligand binding by the hexameric histidine tag on H subunit (HHisRC). The binding constant of HHisRC to the nickel-nitrilotriacetic acid (Ni-NTA) chip measured with a surface plasmon resonance instrument was 1.6 x 10(8) M-1. HHisRCs were immobilized on an indium tin oxide electrode overlaid with an Ni-NTA gold substrate. The photoinduced displacement current of this electrode was measured to estimate the orientation of HHisRC on the electrode, and the detachability of HHisRC from the electrode was determined by using an imidazole solution wash. The direction of the flash-light-induced displacement current suggested that the H subunit side of the immobilized HHisRC faced the surface of the electrode. The photoinduced current disappeared after the electrode was washed in the imidazole solution. This simple immobilization and detachment of HHisRC to the electrode might be useful for making a reproducible photocurrent device.

Biosensing Techniques↗

PubMed2000

Parietal cheiro-oral syndrome.

Cheiro-oral syndrome due to a parietal lesion has been reported in conjuction with a brain tumor, infarction and migraine. Only six reports of cheiro-oral syndrome due to a parietal infarction have been reported to date. We treated a 45-year-old woman with cheiro-oral syndrome due to a parietal infarction. Her sensory disturbance was characterized by paresthesia in the lower face and hand on the left side, and severe involvement of stereognosis and graphesthesia in the left hand. The pathogenesis of parietal cheiro-oral syndrome is discussed.

Cerebral Infarction↗

PubMed2000

Technetium tin colloid test detecting symptomless dysphagia and ACE inhibitor prevented occurrence of aspiration pneumonia.

Symptomless dysphagia and swallowing disorders play a very important role in the pathogenesis of aspiration pneumonia. A videofluoroscopic examination and a simple two-step swallowing provocation test (STS-SPT) could be useful for detection of swallowing disorders in elderly patients with stroke, however, there is no report on such a test for detection of symptomless dysphagia. We administered 1 ml Technetium Tin Colloid (99mTC) to the patient during sleep via a nasal catheter placed in the mouth. At 09:00 h the next day, symptomless dysphagia was checked for by imaging. Improvement of the symptomless dysphagia was observed, and thus we could prevent the occurrence of aspiration pneumonia. The 99mTC test was particularly useful in detecting symptomless dysphagia in elderly patients with stroke.

Aged↗

PubMed2000

Immunohistochemical expression of glutathione transferase-pi in untreated primary non-small-cell lung cancer.

Patients with unresectable non-small-cell lung cancer (NSCLC) usually have undergone chemotherapy; however, such problems as resistance to chemotherapeutic agents occur during the treatments. Recent studies have indicated that glutathione S-transferase-pi (GST-pi) may play an important role in the resistance of cancer cells to alkylating agents, including cisplatin compounds. We examined a possible relationship between immunohistochemical expression of GST-pi and the response to cisplatin plus etoposide chemotherapy in patients with untreated and unresectable primary NSCLC. Of the 89 patients, 50 (56.2%) were GST-pi-positive and 39 (43.8%) were GST-pi-negative. For the patients with negative GST-pi expression, the response rate was 66.7% (26 of 39 patients). In the patients with positive GST-pi expression, the response rate was 26% (13 of 50 patients). This difference was statistically significant (P = .0019). The results suggest that GST-pi expression in NSCLC tissues is related to response to cisplatin plus etoposide chemotherapy and may be useful as a predictor of chemotherapy response.

Adenocarcinoma↗

PubMed1999

Inhibition of hydrogen peroxide-induced apoptosis but not arachidonic acid release in GH3 cell by EGF.

Reactive oxygen species (ROS) and arachidonic acid (AA) can both function as extra- and intra-cellular messengers to regulate various cell functions including cell death. The effect of ROS on phospholipase A2 (PLA2) activity and/or AA release has not been extensively studied in neuronal cells. In this study, we investigated the effects of H2O2 on AA release and apoptosis in GH3 cells, a clonal strain from rat anterior pituitary. Incubation with H2O2 for 1 h stimulated [3H]AA release in a concentration-dependent manner from prelabeled GH3 cells. [3H]AA release was inhibited by arachidonyl trifluoromethyl ketone, a specific inhibitor of cytosolic PLA2, and cytosolic PLA2 protein with a molecular mass of 100 kDa was detected by immunoblotting. Culture with 0.2 mM H2O2 and 30 microM AA for 24 h induced lactate dehydrogenase (LDH) leakage, DNA laddering and DNA fragmentation in GH3 cells. In GH3 cells pretreated with EGF (50 ng/ml) for 24 h, LDH leakage and DNA fragmentation by H2O2 and AA were inhibited, although H2O2-induced [3H]AA release was not modified. Mastoparan, a wasp venom peptide, induced [3H]AA release and cell death in GH3 cells. Neither effect of mastoparan was inhibited by EGF treatment. These findings suggest that (1) H2O2 stimulates AA release via activation of cytosolic PLA2, (2) H2O2 and AA induce apoptotic death of GH3 cells and (3) treatment with EGF protects H2O2- and AA-, but not mastoparan-, induced GH3 cell death.

Animals↗

PubMed1999

Remodeling of cell-cell and cell-extracellular matrix interactions at the border zone of rat myocardial infarcts.

At the border zone of myocardial infarcts, surviving cardiomyocytes achieve drastic remodeling of cell-cell and cell-extracellular matrix interactions. Spatiotemporal changes in these interactions are likely related to each other and possibly have significant impact on cardiac function. To elucidate the changes, we conducted experimental infarction in rats and performed 3-dimensional analysis of the localization of gap junctions (connexin43), desmosomes (desmoplakin), adherens junctions (cadherin), and integrins (beta(1)-integrin) by immunoconfocal microscopy. After myocardial infarction, changes in the distribution of gap junctions, desmosomes, and adherens junctions showed a similar but nonidentical tendency. In the early phase, gap junctions almost disappeared at stumps (longitudinal edges of cardiomyocytes facing the infarct), and, although desmosomes and adherens junctions decreased, they still remained. In the healing phase, at stumps, connexin43, desmoplakin, and cadherin were closely associated between multiple cell processes originating from a single cardiomyocyte. Electron microscopy confirmed the presence of junctional complexes between the cell processes. beta(1)-Integrin at the cell process increased during the formation of papillary myotendinous junction-like structures. Abnormal localization of connexin43 was often accompanied by desmoplakin and cadherin on lateral surfaces of surviving cardiomyocytes. These findings suggested that remodeling of gap junction distribution was closely linked to changes in desmosomes and adherens junctions and that temporary formation of intracellular junctional complexes was an element of the remodeling of cell-cell and cell-extracellular matrix interactions after myocardial infarction. Moreover, the remodeling of the intercalated disk region at the myocardial interface with area of scar tissues was associated with the acquisition of extracellular matrix and beta(1)-integrin.

Animals↗

PubMed1999

Induction of systemic and mucosal antibody responses in mice immunized intranasally with aluminium-non-adsorbed diphtheria toxoid together with recombinant cholera toxin B subunit as an adjuvant.

Nasal mucosal immunization is very attractive for vaccination to prevent various bacterial and viral infectious diseases because of induction of systemic and mucosal immune responses. The aim of the present study was to investigate the possibility of changing the immunization procedure of diphtheria toxoid (DT) from intramuscular or subcutaneous injection to intranasal administration. Intranasal immunization with aluminium-non-adsorbed diphtheria toxoid (nDT) together with recombinant cholera toxin B subunit (rCTB, 10 microg) induced, at a concentration of 5 Lf, high levels of serum DT-specific IgG antibody responses and high or moderate levels of the specific IgA antibody responses in all mice and only a slight level of the specific IgE antibody responses in some mice. Furthermore, sufficiently high diphtheria antitoxin titres more than 0.1 international units (IU) ml(-1) were obtained from mice which showed high levels of serum DT-specific IgG antibody responses. Under the same experimental conditions, induction of significant levels of mucosal DT-specific IgA antibody responses occurred in the nasal cavity, the lung, the saliva and vaginal secretions and the small and large intestines of all mice, although there were different titres between individual mice. Similar results were also obtained with rCTB-specific serum IgG and IgA and mucosal IgA antibody responses; serum rCTB-specific IgE antibody titres were not detected. These results show that intranasal administration of nDT with rCTB must be a very useful means for vaccination against diphtheria.

Adjuvants, Immunologic↗

PubMed1999

Evaluation of cationic liposome suitable for gene transfer into pregnant animals.

Cationic liposome-mediated in vivo gene transfer represents a promising approach for somatic gene therapy. To assess the most suitable liposome for gene delivery into a wide range of organs and fetuses in mice, we have explored several types of cationic liposomes conjugated with plasmid DNA carrying the beta-galactosidase gene through intravenous injection into pregnant animals. Transduction efficiency was assessed by Southern blot analysis and expression of the transferred gene was evaluated by enzymatic demonstration of beta-galactosidase activity. Through the analysis of several types of recently synthesized cationic liposome/lipid formulations, DMRIE-C reagent, a liposome formulation of the cationic lipid DMRIE (1, 2-dimyristyloxypropyl-3-dimethyl-hydroxy ethyl ammonium bromide) and cholesterol in membrane-filtered water met our requirements. When the plasmid DNA/DMRIE-C complexes were administered intravenously into pregnant mice at day 11.5 post coitus (p.c.), transferred genes were observed in several organs in dams and were expressed. Furthermore, although the copy numbers transferred into embryos were low, we observed reporter gene expression in the progeny.

Animals↗

PubMed1999

Intranasal or subcutaneous co-administration of recombinant cholera toxin B subunit stimulates only a slight or no level of the specific IgE response in mice to tetanus toxoid.

Whether recombinant cholera toxin B subunit (rCTB) co-administered intranasally or subcutaneously with aluminium-non-adsorbed tetanus toxoid (nTT) can induce the production of tetanus toxoid (TT)-specific IgE antibodies in mice was investigated compared with aluminium-adsorbed tetanus toxoid (aTT) administered intranasally or subcutaneously. Mice immunized intranasally or subcutaneously with nTT together with rCTB showed a high level of TT-specific serum IgG antibody response and no or a slight level of TT-specific serum IgE antibody response. On the other hand, in mice vaccinated intranasally or subcutaneously with aTT alone, higher levels of TT-specific IgG and IgE antibodies were induced in comparison with intranasal or subcutaneous inoculation of nTT together with rCTB. These results suggest that intranasal or subcutaneous co-administration of rCTB with nTT is better than intranasal or subcutaneous administration of aTT to avoid IgE-mediated allergic reactions.

Adjuvants, Immunologic↗

PubMed1999

Pancreatic bladder or double gallbladder draining into pancreatic duct?

We report a case of pancreatic bladder which could also be interpreted as double gallbladder draining into the pancreatic duct. A 6-year-old Japanese boy underwent a cholecystectomy of the smaller bladder under the diagnosis of duplication of the gallbladder, leaving the normal gallbladder and an unremarkable biliary ductal system. The smaller bladder was histologically similar to the gallbladder tissue. At age 25, relaparotomy was performed. It was confirmed that the residual aberrant duct from the smaller bladder joined directly with the duct of Wirsung and that the patient had fusiform dilatation of the extrahepatic bile duct. The extrahepatic portion of the bile duct was excised along with the "normal" gallbladder and the residual aberrant duct. The present anomaly seems to validate the designation of pancreatic bladder whose cystic duct joined directly with the pancreatic duct, but may also be explained from the view point of double gallbladder.

Bile Ducts↗

PubMed1999

Preoperative assessment of congenital bile duct dilatation using intraductal US.

BACKGROUND: Although congenital bile duct dilatation is frequently associated with biliary tract cancer, conventional cholangiography often does not demonstrate small ductal tumors. This is the first prospective study of the value of intraductal ultrasonography (US) in the examination of the extrahepatic bile ducts in patients with congenital bile duct dilatation. METHODS: Intraductal US via a transpapillary route was used in consecutive patients with congenital bile duct dilatation. A 2.0 mm diameter, 20 MHz frequency catheter probe was used. The images were correlated with the results of histologic examination of the resection specimens. RESULTS: Intraductal US was performed successfully via the transpapillary route in 8 of 10 patients. In the other 2 patients, the percutaneous transhepatic route was used. In the 6 patients with cylindrical dilatation, intraductal US demonstrated the entire extrahepatic bile duct. In 1 patient, it showed a bile duct cancer not demonstrated by cholangiography. In 2 of the 4 patients with cystic dilatation, intraductal US did not demonstrate the entire extrahepatic bile duct because of the low penetration depth of the probe. Percutaneous transhepatic cholangioscopy was required in these patients. CONCLUSIONS: Intraductal US is useful for demonstrating cancers in the extrahepatic bile ducts in patients with congenital cylindrical ductal dilatation.

Adult↗

PubMed1999

Role of interleukin-12 in the development of acute graft-versus-host disease in bone marrow transplant patients.

Interleukin-12 (IL-12) is a crucial cytokine regulating cell-mediated immunity, and may contribute to the development of graft-versus-host disease (GVHD). We investigated serum IL-12 concentrations, interferon gamma (IFN-gamma) production by peripheral blood lymphocytes (PBL) from allogeneic stem cell recipients after IL-12 plus anti-CD3 monoclonal antibody (mAb) stimulation. We also investigated IL-12 production by peripheral macrophages (Mphi) after lipopolysaccharide (LPS) stimulation from allogeneic stem cell recipients and patients receiving donor leukocyte transfusions (DLT) for treatment or prophylaxis of leukemia relapse and Epstein-Barr virus (EBV) lymphoproliferative disease (LPD). PBL from acute GVHD patients produced high IFN-gamma levels after IL-12 plus anti-CD3 mAb stimulation, whereas PBL from patients without acute GVHD produced low levels of IFN-gamma. However, serum IL-12 concentrations were low in both groups. Peripheral Mphi IL-12 production increased in patients who developed acute GVHD compared to patients without acute GVHD. Five patients receiving DLT for treatment or prophylaxis of leukemia relapse developed acute GVHD. IFN-gamma production by PBL stimulated by IL-12 plus anti-CD3 mAb increased, while IL-12 production by peripheral Mphi stimulated by LPS was very high after the development of acute GVHD. However, serum IL-12 concentration remained low. Three patients receiving DLT for EBV-LPD did not develop acute GVHD with no increase of IFN-gamma and IL-12 production. These results indicate that IL-12 may play an important role in the development of acute GVHD after allogeneic stem cell grafting or DLT, and increased IL-12 production by Mphi occurs with various stimuli, including LPS.

Acute Disease↗

PubMed1999

Role of N-glycosylation in cathepsin E. A comparative study of cathepsin E with distinct N-linked oligosaccharides and its nonglycosylated mutant.

Cathepsin E (CE), a nonlysosomal, intracellular aspartic proteinase, exists in several molecular forms that are N-glycosylated with high-mannose and/or complex-type oligosaccharides. To investigate the role of N-glycosylation on the catalytic properties and molecular stability of CE, both natural and recombinant enzymes with distinct oligosaccharides were purified from different sources. An N-glycosylation minus mutant, that was constructed by site-directed mutagenesis (by changing asparagine residues to glutamine and aspartic acid residues at positions 73 and 305 in potential N-glycosylation sites of rat CE) and expressed in normal rat kidney cells, was also purified to homogeneity from the cell extracts. The kinetic parameters of the nonglycosylated mutant were found to be essentially equivalent to those of natural enzymes N-glycosylated with either high-mannose or complex-type oligosaccharides. In contrast, the nonglycosylated mutant showed lower pH and thermal stabilities than the glycosylated enzymes. The nonglycosylated mutant exhibited particular sensitivity to conversion to a monomeric form by 2-mercaptoethanol, as compared with those of the glycosylated enzymes. Further, the high-mannose-type enzymes were more sensitive to this agent than the complex-type proteins. A striking difference was found between the high-mannose and complex-type enzymes in terms of activation by ATP at a weakly acidic pH. At pH 5.5, the complex-type enzymes were stabilized by ATP to be restored to the virtual activity, whereas the high-mannose-type enzymes as well as the nonglycosylated mutant were not affected by ATP. These results suggest that N-glycosylation in CE is important for the maintenance of its proper folding upon changes in temperature, pH and redox state, and that the complex-type oligosaccharides contribute to the completion of the tertiary structure to maintain its active conformation in the weakly acidic pH environments.

Adenosine Triphosphate↗

PubMed1999

Limitation of cholangiography in assessing longitudinal spread of extrahepatic bile duct carcinoma to the hepatic side.

BACKGROUND: Preoperative assessment of longitudinal spread of bile duct carcinoma (BDC) to the hepatic side remains a difficult problem for diagnostic imaging. METHODS: We studied the accuracy of cholangiography in assessing BDC. In 54 patients with extrahepatic bile duct cancer, cholangiographic findings were compared retrospectively with the histological findings of the resected specimens. RESULTS: Histological examination of specimens indicated longitudinal spread of the tumour to the hepatic side in 22 of 54 patients. The accuracy of cholangiography in assessing the extent of the longitudinal spread was only 34/54 (63%). When the cholangiographic images showed a main tumour with a collapsed edge, there was a significantly higher frequency of longitudinal spread compared with tumours with sharp edges (P< 0.05). In contrast, the accuracy of mapping biopsy under percutaneous transhepatic cholangioscopy (n=24) was 83%. CONCLUSIONS: Cholangiography cannot accurately assess the extent of the longitudinal spread of bile duct cancer. When cholangiographic images show a tumour with a collapsed edge, preoperative or intraoperative histological examination is essential to determine a suitable surgical line.

Adenocarcinoma↗

PubMed1999

Influence of hemodialysis membrane type on pentosidine plasma level, a marker of "carbonyl stress".

UNLABELLED: Influence of hemodialysis membrane type on pentosidine plasma level, a marker of "carbonyl stress." BACKGROUND: The accumulation of advanced glycation end products (AGEs) in uremia has been ascribed to the retention of carbonyl precursors of AGEs. Pentosidine plasma level has been identified as a surrogate marker of carbonyl precursors ("carbonyl stress"). The influence of hemodialysis (HD) membrane type and residual diuresis on carbonyl stress has not been studied. METHODS: We measured protein-linked and free plasma pentosidine (a surrogate marker of carbonyl stress) by high-performance liquid chromatography in patients on HD with low-flux cellulose (N = 29), high-flux polysulfone (PS; N = 57), polymethylmethacrylate (PMMA) (N = 25), and AN69 (N = 15). RESULTS: Both protein-linked and free pentosidine were similar on low-flux cellulose, high-flux PMMA, and AN69, but were lower (P < 0.01) on high-flux PS. Pentosidine levels were virtually identical on Fresenius and Asahi PS in Japanese and Belgian patients. By multivariate analysis, only the type of HD membrane and residual diuresis proved to be independent determinants (P < 0.001) of pentosidine levels. During a single HD session, the clearance of free pentosidine was similar with all membranes. In three patients who were switched from AN69 to PS, the protein-linked pentosidine level dropped to the control level after resumption of the AN69 membrane. CONCLUSIONS: Both HD membrane type and residual diuresis are independent determinants of pentosidine plasma level, which is a marker of carbonyl stress.

Aged↗

PubMed1999

Characterization of new fluorogenic substrates for the rapid and sensitive assay of cathepsin E and cathepsin D.

Cathepsin E and cathepsin D are two major intracellular aspartic proteinases implicated in the physiological and pathological degradation of intra- and extracellular proteins. In this study, we designed and constructed highly sensitive synthetic decapeptide substrates for assays of cathepsins E and D based on the known sequence specificities of their cleavage sites. These substrates contain a highly fluorescent (7-methoxycoumarin-4-yl)acetyl (MOCAc) moiety and a quenching 2,4-dinitrophenyl (Dnp) group. When the Phe-Phe bond is cleaved, the fluorescence at an excitation wavelength of 328 nm and emission wavelength of 393 increases due to diminished quenching resulting from the separation of the fluorescent and quenching moieties. The first substrate, MOCAc-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the Lys-Pro combination at positions P5 and P4 was designed for specific interaction with cathepsin E, is hydrolyzed equally well by cathepsins E and D (kcat/Km = 10.9 microM(-1) x s(-1) for cathepsin E and 15.6 microM(-1) x s(-1) for cathepsin D). A very acidic pH optimum o was obtained for both enzymes. The second substrate, MOCAc-Gly-Lys-Pro-Ile-Ile-Phe-Phe-Arg-Le u-Lys(Dnp)gamma-NH2, in which the isoleucine residue at position P2 was meant to increase the specificity for cathepsin E, is also hydrolyzed equally by both enzymes (kcat/Km = 12.2 microM(-1) x s(-1) for cathepsin E and 16.3 microM(-1) x s(-1) for cathepsin D). The kcat/Km values for both substrates are greater than those for the best substrates for cathepsins E and D described so far. Unfortunately, each substrate shows little discrimination between cathepsin E and cathepsin D, suggesting that amino acids at positions far from the cleavage site are important for discrimination between the two enzymes. However, in combination with aspartic proteinase inhibitors, such as pepstatin A and Ascaris pepsin inhibitor, these substrates enable a rapid and sensitive determination of the precise levels of cathepsins E and D in crude cell extracts of various tissues and cells. Thus these substrates represent a potentially valuable tool for routine assays and for mechanistic studies on cathepsins E and D.

Amino Acid Sequence↗

PubMed1999

Keloids have continuous high metabolic activity.

The adenosine triphosphate (ATP) content of keloids and scars resected from patients was demonstrated by high-performance liquid chromatography. The surface color of hypertrophic scars was red or pink and that of atrophic scars was white. The ATP content of red scars was (in mmol/g protein) 1.06 +/- 0.14, of pink scars 0.12 +/- 0.02, of white atrophic scars 0.19 +/- 0.06, and of keloids 1.06 +/- 0.19. The longer the elapsed time after the trauma, the lower the level of ATP in scar tissues (correlation coefficient = -0.506; p = 0.005 by Spearman's rank correlation). However, ATP levels in keloids were still high 10 years after the injury. Fibroblasts and fibrocytes in keloids and scars were counted in histologic preparations stained with hematoxylin and eosin. The average number of fibroblasts in a definite area (56 x 10(-4) mm at a magnification of x400) was 4.8 in keloids, 5.1 in red scars, 2.4 in pink scars, and 1.3 in white atrophic scars. The number of fibrocytes in the same area was 0.4 in keloids, 0.4 in red scars, 2.3 in pink scars, and 1.3 in white atrophic scars. These results indicate that keloids and red hypertrophic scars have higher ATP levels and contain more fibroblasts than pink or white scars, and they also suggest that the levels of ATP and the number of fibroblasts decrease when red hypertrophic scars change into atrophic scars. In keloids, ATP and fibroblasts seem to remain at high levels for a long time.

Adenosine Triphosphate↗

PubMed1999

The gene encoding the prepilin peptidase involved in biosynthesis of pilus colonization factor antigen III (CFA/III) of human enterotoxigenic Escherichia coli.

The assembly of pilus colonization factor antigen III (CFA/III) of human enterotoxigenic Escherichia coli requires the processing of CFA/III major pilin (CofA) by a peptidase, likely another type IV pilus formation system. Western blot analysis of CofA reveals that CofA is produced initially as a 26.5-kDa preform pilin (prepilin) and then processed to 20.5-kDa mature pilin by a prepilin peptidase. This processing is essential for exportation of the CofA from the cytoplasm to the periplasm. In this experiment, the structural gene, cofP, encoding CFA/III prepilin peptidase which cleavages at the Gly-30-Met-31 junction of CofA was identified, and the nucleotide sequence of the gene was determined. CofP consists of 819 bp encoding a 273-amino acid protein with a relative molecular mass of 30,533 Da. CofP is predicted to be localized in the inner membrane based on its hydropathy index. The amino acid sequence of CofP shows a high degree of homology with other prepilin peptidases which play a role in the assembly of type IV pili in several gram-negative bacteria.

Amino Acid Sequence↗