Biomedical subjects

I Watanabe

Publications and source records attributed to I Watanabe.

At least 37 records · Page 2Linked to original sources

PubMed2002

Accumulation of heavy metals in Caspian seals (Phoca caspica).

Concentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co, and Hg) were determined in the muscle, liver, and kidney of 42 Caspian seals and fishes collected from the Caspian Sea in 1993. Higher Mn and lower Fe and Cu concentrations were found in the liver in comparison with other marine pinnipeds. Lower Cu concentrations in the liver appear to be a common feature in small seals belonging to subgenus Pusa, which include ringed, Baikal, and Caspian seals. However, low Fe and high Mn in livers were specific to Caspian seal. Concentrations of toxic metals such as Hg and Cd were relatively low. Pinniped species can be divided into two groups, based on accumulations of Cd or Hg in the liver. Interestingly, it was found that Cd-accumulating groups feed on invertebrates, whereas the preferred diet of Hg accumulators is fish. Caspian seals seemed to belong to the Hg-accumulating group.Cd and Hg concentrations in the liver and kidney of young animals increased with age. Mercury concentrations in adult animals increased with age continuously, whereas Cd concentrations in adult animals decreased. This trend might be due to preferential feeding habits and shift in ratio of Hg and Cd in the diet ( i.e., invertebrates to fish).

Age Factors↗

PubMed2002

Joint strength of laser-welded titanium.

OBJECTIVE: The objective of this study was to examine the joint strength of titanium laser-welding using several levels of laser output energy [current (A)]. METHODS: Cast titanium plates (0.5 x 3.0 x 40 and 1.0 x 3.0 x 40 mm(3)) were prepared and perpendicularly cut at the center of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser at several levels of output energy in increments of 30A from 180 to 300A. The penetration depths of laser to titanium were measured under various conditions for output energy, pulse duration, and spot diameter to determine the appropriate conditions for these parameters. Based on the correlation between the results obtained for penetration depth and the size of the specimens (thickness: 0.5 and 1.0 mm, width: 3.0 mm), the pulse duration and spot diameter employed in this study were 10 ms and 1.0 mm, respectively. Three laser pulses (spot diameter: 1.0 mm) were applied from one side to weld the entire joint width (3.0 mm) of the specimens. Uncut specimens served as the non-welded control specimens. Tensile testing was conducted at a crosshead speed of 2 mm/min and a gage length of 10 mm. The breaking force (N) was recorded, and the data (n=5) were statistically analyzed. RESULTS: For the 0.5 mm thick specimens, the breaking force of the specimens laser-welded at currents of 240, 270, and 300A were not statistically (P>0.05) different from the non-welded control specimens. There were no significant differences in breaking force among the 1.0mm thick specimens laser-welded at currents of 270 and 300A, and the non-welded control specimens. SIGNIFICANCE: Under appropriate conditions, joint strengths similar to the strength of the non-welded parent metal were achieved.

Aluminum Silicates↗

PubMed2002

Angioarchitectural characteristics of the anterodorsal surface of aging and young rabbit tongue: scanning electron microscopy study.

The three-dimensional angioarchitecture of young and aging rabbit tongues were studied using a vascular corrosion cast method. The vascular network of different lingual papillae were observed by scanning electron microscope (SEM). Young animals showed filiform papillae distributed all over considered area, with fungiform ones among them. In comparison to developed specimens, young rabbits demonstrated dense and higher organization of microvascular network.

Aging↗

PubMed2002

Three-dimensional architecture of the connective tissue core and surface structures of the lingual papillae in the rabbit.

Three-dimensional characteristics of the epithelial cell layer and connective tissue interface of the tongue were studied using scanning electron microscopy. In this study, the fragments of tongue were fixed in modified Karnovsky's fixative solution. Subsequently, the specimens were treated with 10% NaOH solution for 4-7 days at room temperature and postfixed in 1% OsO4 in 0.1 M phosphate buffer (pH 7.4) for 2 hours at 4 degrees C. They were dehydrated through a graded ethanol series, and critical-point dried with CO2. The specimens were coated with gold and observed in a scanning electron microscope, JEOL JSM-6100. The results showed numerous papillae on the dorsal surface of the tongue divided into four groups (filiform, fungiform, foliate and vallate papillae). Filiform papillae are conically shaped; fungiform papillae have an irregular round surface; foliate papillae are oval in shape and have some parallel projections; and vallate papillae are located in the posterior part of the tongue and have a depression around the center. After the treatment with 10% NaOH solution, the original arrangements of connective papillae could be seen. This characteristic three-dimensional distribution of the collagen fiber bundles is typical for each superficial papillae depending on whether it is filiform, fungiform, foliate or vallate.

Animals↗

PubMed2001

Difference in cholesterol-binding and cytolytic activities between listeriolysin O and seeligeriolysin O: a possible role of alanine residue in tryptophan-rich undecapeptide.

We have constructed recombinant listeriolysin O (rLLO) and seeligeriolysin O (rLSO) from Listeria monocytogenes and Listeria seeligeri, respectively. In hemolysis and cholesterol-binding assays, the specific activity of recombinant toxin was lower for LSO as compared to LLO. To understand the molecular basis of this difference, in particular with respect to the conserved Trp-rich undecapeptide, a naturally occurring Ala to Phe substitution in LSO was introduced into rLLO. The rLLO:A488F hemolysin exhibited a reduced activity in both hemolysis and cholesterol-binding. The reverse mutation, inserted into rLSO, also increased the hemolytic activity of this mutant LSO. These results suggested that the natural replacement of Ala to Phe is involved in the weak cytolytic activity of LSO.

Alanine↗

PubMed2001

Determinants involved in Kv1 potassium channel folding in the endoplasmic reticulum, glycosylation in the Golgi, and cell surface expression.

Kv1.1 and Kv1.4 potassium channels are expressed as mature glycosylated proteins in brain, whereas they exhibited striking differences in degree of trans-Golgi glycosylation conversion and high cell surface expression when they were transiently expressed as homomers in cell lines. Kv1.4 exhibited a 70% trans-Golgi glycosylation conversion, whereas Kv1.1 showed none, and Kv1.4 exhibited a approximately 20-fold higher cell surface expression level as compared with Kv1.1. Chimeras between Kv1.4 and Kv1.1 and site-directed mutants were constructed to identify amino acid determinants that affected these processes. Truncating the cytoplasmic C terminus of Kv1.4 inhibited its trans-Golgi glycosylation and high cell surface expression (as shown by Li, D., Takimoto, K., and Levitan, E. S. (2000) J. Biol. Chem. 275, 11597-11602), whereas truncating this region on Kv1.1 did not affect either of these events, indicating that its C terminus is not a negative determinant for these processes. Exchanging the C terminus between these channels showed that there are other regions of the protein that exert a positive or negative effect on these processes. Chimeric constructs between Kv1.4 and Kv1.1 identified their outer pore regions as major positive and negative determinants, respectively, for both trans-Golgi glycosylation and cell surface expression. Site-directed mutagenesis identified a number of amino acids in the pore region that are involved in these processes. These data suggest that there are multiple positive and negative determinants on both Kv1.4 and Kv1.1 that affect channel folding, trans-Golgi glycosylation conversion, and cell surface expression.

Amino Acid Sequence↗

PubMed2001

Expression of survivin correlates with apoptosis, proliferation, and angiogenesis during human colorectal tumorigenesis.

BACKGROUND: To identify the role of survivin, a novel inhibitor of apoptosis (IAP) in colorectal tumorigenesis, the authors investigated tissue expression of survivin in human colorectal tumors including 43 hyperplastic polyps, 171 adenomas with low dysplasia, 42 adenomas with high dysplasia, and 60 carcinomas in adenoma, and examined whether the expression of survivin correlated with tumor cell apoptosis, proliferation, and angiogenesis, which is known to initiate the imbalance between cell proliferation and apoptosis. METHODS: Immunohistochemical staining for the paraffin sections by using the monoclonal antibodies, survivin, p53, bcl-2, Ki-67, and CD34, was performed by the standard avidin-biotin-peroxidase technique. The apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method, using an Apop Tag in situ detection kit. RESULTS: The immunoreactivity of survivin significantly increased in the transition from adenoma with low dysplasia to high dysplasia/carcinoma (P < 0.001). Similar changes in protein expression were observed for p53 but not for bcl-2, which was expressed throughout the colorectal tumorigenesis. This transition was associated with a significant decrease in the apoptotic index (AI) and significant increases in the Ki-67 labeling index (LI) and microvessel density (MVD; P < 0.001 for both). The expression of survivin inversely correlated with AI and was positively correlated with Ki-67 LI and MVD (P < 0.001 for both). CONCLUSIONS: These results suggest that, like p53, survivin plays an important role in transition from adenoma with low dysplasia to high dysplasia during human colorectal tumorigenesis.

Adenoma↗

PubMed2001

XAFS analysis of corroded metal surfaces with molten salts by conversion-electron-yield method.

We have measured XAFS spectra of metal surfaces corroded with melting salt (NaCl, KCl, and Na2SO4). Steel samples used were S45C, SCM435, SUS310S, and SUS304. We measured the Fe K-edge XAFS spectra for all samples and the Ni K-edge for SUS310S and SUS304 samples before and after the corrosion. The XANES spectra of samples before the corrosion show metallic structure because surface oxide thickness is thinner than probing depth with a conversion yield XAFS method. Each result of these XAFS spectra gives good agreements with the FEFF calculation in the assumption of bcc and/or fcc structure. The Fe K-edge spectra of steel samples except SUS310S after corroded treatment show existence bonding between Fe and another light element although the spectra of SUS310S samples before and after corroded treatment are much the same.

Journal Article↗

PubMed2001

Determination of dissociation energy for ligand exchange reaction from EXAFS.

EXAFS (extended X-ray absorption fine structure) experiments were performed at several different temperatures for a series of 3d transition metal ions (Cr3+, Fe3+, Fe2+, Ni2+, Co2+, Zn2+) in aqueous solutions. Anharmonic EXAFS analyses, which include up to third order cumulant, were carried out to study on the metal-oxygen bonding potential. According to the model in which the dissociation process is dominant for the ligand-water exchange reaction, the dissociation energy has been first evaluated from EXAFS in solution phase.

Journal Article↗

PubMed2001

XAFS analysis of triiodide ion in solutions.

Iodine K-edge XAFS of triiodide ions in various solvents were measured at SPring-8 BL01B1 and analyzed. Though the anion takes a linear and symmetric form, the second peak expected from enhanced multiple scatterings can be hardly observed because of its large vibrations. The bond distances and the Debye-Waller factors for the I-I couple vary when protic solvents were used and they were similar when aprotic solvents were used. It was indicated that the larger the Mayers' acceptor number of the solvent is, the larger the Debye-Waller factor is. It was also found that among the aprotic solvents, the larger the Gutmann's donor number is, the smaller the Debye-Waller factor is.

Journal Article↗

PubMed2001

Essential role of domain 4 of pneumolysin from Streptococcus pneumoniae in cytolytic activity as determined by truncated proteins.

Pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae, is one of the members of thiol-activated cytolysins (TACYs) consisting of four domains. TACYs commonly bind to membrane cholesterol and oligomerize to form transmembrane pore. We have constructed full-length and various truncated PLYs to study the role of domains of PLY in the cytolytic activity. Full-length PLY had binding ability to both cell membrane and immobilized cholesterol. A truncated PLY which comprised only domain 4 molecule, the C-terminal domain of PLY, sustained the binding ability to cell membrane and cholesterol, whereas domain 1-3 molecule had no binding ability to them. Furthermore, the domain 4 molecule inhibited both the membrane binding and the hemolytic activity of full-length PLY. Accordingly, the present results provided the direct evidence that domain 4 was essential for the initial binding to membrane cholesterol and the interaction led to the subsequent membrane damage process.

Animals↗

PubMed2001

Attractive force of castable iron-platinum magnetic alloys.

OBJECTIVE: The objective of this study was to examine the attractive force of cast Fe-Pt alloys of varying compositions to dental iron-neodymium-boron magnets. METHODS: Ingots of Fe-40 at%Pt, Fe-38 at%Pt, Fe-37 at%Pt and Fe-36 at%Pt alloys were cast in pattern molds for dental magnetic attachment keepers. The attractive forces of the cast Fe-Pt alloy keepers and magnetic stainless steel keepers to dental Fe(14)Nd(2)B magnets (MAGFIT and HICOREX) were measured and statistically evaluated. The saturation magnetization of each Fe-Pt alloy was determined by recording the hysteresis loop using a vibrating sample magnetometer under a magnetic field of 1.6 MA/m. RESULTS: Decreasing the Pt percentage increased the saturation magnetization value and resulted in an increase of the attractive force to each magnet. There was no statistical difference (p>0.05) in attractive force between the Fe-36 at%Pt alloy specimens and the stainless steel keepers for both magnets. A definite correlation between Pt percentage and the value of saturation magnetization was also found (r(2)=-1.000). SIGNIFICANCE: The Fe-Pt alloys with less than Fe-39.5 at%Pt produced high saturation magnetization values and great attractive force to the magnet, and thus, they have the potential to serve as magnetic attachment keepers. Of the Fe-Pt alloys tested, Fe-36 at%Pt seemed to be the best composition for making magnetic attachment keepers.

Analysis of Variance↗

PubMed2001

In vitro corrosion behavior of cast iron-platinum magnetic alloys.

OBJECTIVE: The objective of this study was to investigate the corrosion resistance of cast Fe-Pt alloys of varying compositions for use as attachment keepers and to make a comparison with the corrosion resistance of magnetic stainless steel. METHODS: The corrosion behavior of cast Fe-Pt alloy keepers (Fe-40 at%Pt, Fe-38 at%Pt, Fe-37 at%Pt and Fe-36 at%Pt) was evaluated by means of an immersion test and an anodic polarization test. The solutions used were a 1.0% lactic acid aqueous solution (pH=2.3) (10 ml) and 0.9% NaCl solution (pH=7.3) (10 ml). As a control, the corrosion resistance of a magnetic stainless steel keeper (SUS 447J1: HICOREX) was also measured. RESULTS: Chromium and platinum ions were not detected in either the 1.0% lactic acid or 0.9% NaCl solutions. The only released ions detected were the Fe ions in the 1.0% lactic acid solution. The amounts of Fe ions released from the Fe-40 at%Pt and Fe-38 at%Pt alloys were significantly (p<0.05) lower than from the Fe-37at%Pt, Fe-36 at%Pt and SUS 447J1 alloys. In the anodic polarization test, the potentials at the beginning of passivation for the four Fe-Pt alloys were higher than for the SUS 447J1 alloy in both solutions. SIGNIFICANCE: The Fe-Pt alloys, especially the alloys with higher Pt percentages (Fe-40 and 38 at%Pt), indicated a high corrosion resistance compared to the magnetic stainless steel keeper. A reduction in the Pt percentage may decrease the corrosion resistance in the oral environment.

Chromium↗

PubMed2001

Effect of heat treatment on mechanical properties of age-hardenable gold alloy at intraoral temperature.

OBJECTIVE: The aim of this study was to investigate the effect of various heat treatments on the mechanical properties of gold alloys capable of age-hardening at intraoral temperature. METHODS: Dumbbell-shaped patterns (ISO 6871) were cast with three gold alloys (Sofard; NC Type-IV; Aurum Cast, NihombashiTokuriki Co.). The Sofard alloy is age-hardenable at intraoral temperature. The castings underwent various heat treatments [as-cast (AC); solution treatment (ST); high-temperature aging (HA); intraoral aging (IA)]. After these heat treatments, ultimate tensile strength (UTS), 0.2% offset yield strength (YS), and elongation (EL) were measured at a strain rate of 1.7x10(-4)/s. Fracture surfaces of the specimens after tensile testing were observed using SEM. Vickers hardness was also measured after heat treating. RESULTS: After IA, the hardness values of the Sofard alloy increased and reached values similar to the hardness of the Sofard specimens aged at high temperature (HA). The hardness values of the NC Type-IV and Aurum Cast specimens slightly increased after IA, but did not reach the values of the specimens after HA. All the Sofard, NC Type-IV and Aurum Cast specimens showed significantly (P<0.05) greater hardness values after HA, compared with the values after any other heat treatments (AC, ST and IA). The UTS and YS of the specimens indicated a tendency similar to the results obtained for hardness. The Sofard specimens with ST showed the greatest elongation compared to the corresponding NC Type-IV and Aurum Cast specimens. However, the elongation of the Sofard specimens was abruptly reduced after intraoral aging. CONCLUSION: Intraoral aging significantly improved the mechanical properties and hardness of the Sofard alloy.

Analysis of Variance↗

PubMed2001

A double mutation in a patient with X-linked myotubular myopathy.

In this report a double mutation was identified in a patient with X-linked myotubular myopathy. The mutations present in the patient were a C-->T substitution of nucleotide 163, which led to an Arg 55 stop codon (nonsense mutation), and an "A" insertion at nucleotide 440, which caused a shift of the reading frame and a premature stop at codon 153 (frameshift mutation). The nonsense mutation was heterozygously present in the mother but not identified in the father or in normal controls. The frameshift mutation was not identified in either parent or normal controls (de novo mutation). These mutations are predicted to truncate the myotubularin protein.

Codon, Nonsense↗

PubMed2001

X-ray diffraction characterization of dental gold alloy-ceramic interfaces.

X-ray diffraction (XRD) was employed to study dental alloy-ceramic interfaces. A Au-Pd-In alloy, which requires oxidation before porcelain firing, and a Au-Pt-Pd-In alloy, which does not require oxidation before porcelain firing, were selected in this study. Alloy specimens were centrifugally cast. Specimen surfaces were metallographically polished through 0.05 microm Al2O3 slurries. A thin layer (< 50 microm) of a dental opaque porcelain was fired on the alloy surfaces with and without initial oxidation. XRD was conducted at room temperature on four types of alloy specimens: polished, oxidized, porcelain fired after alloy oxidation, and porcelain fired without initial alloy oxidation. XRD was also performed on fired opaque porcelain without an alloy substrate. The detection of prominent gold solid solution peaks from alloy-ceramic specimens indicated that the incident X-ray beam reached the alloy-ceramic interface. In2O3 and beta-Ga2O3 were identified on the oxidized Au-Pd-In alloy, while In2O3 and SnO2 were detected on the oxidized Au-Pt-Pd-In alloy. Preferred orientation was observed for all the oxides formed on the alloys. Minimum lattice parameter changes (<1%) for the gold solid solutions were observed for both alloys before and after oxidation and porcelain firing. Leucite (KAlSi2O6, TiO2, ZrO2 and SnO2 were detected on the fired opaque porcelain. For both alloys, no additional oxides were identified at the metal-ceramic interfaces beyond those present in the oxidized alloys and the opaque porcelain. Similar results were obtained from alloy-ceramic interfaces where there was no prior alloy oxidation. The results indicate the critical role of alloy surface oxides in metal-ceramic bonding and support the chemical bonding mechanism for porcelain adherence.

Journal Article↗

PubMed2001

Frequency-dependent electrophysiological effect of ibutilide on human atrium and ventricle.

Most of the class III antiarrhythmic agents developed in recent years blocks the rapid component of delayed rectifier potassium current (IKr). IKr blocker shows reverse use-dependency and also may cause torsades de pointes at slower heart rate. Ibutilide fumarate, a novel class III antiarrhythmic agent, increases window Na(+) current at the action potential plateau phase. We studied the rate-dependent effect of ibutilide on the electrophysiological parameters of human atrium and ventricle. Franz catheter and a pacing catheter were placed closely in the high right atrium and right ventricular apex to record monophasic action potentials (MAP) during pacing at cycle length (PCL) of 600 ms and 350 ms in eight patients who underwent electrophysiological study. MAP duration of right atrium (RA-MAPD) and right ventricle (RV-MAPD), effective refractory period of RA and RV (RA-ERP and RV-ERP), intra-atrial conduction time (IACT) and intra-ventricular conduction time (IVCT) were measured before and after intravenous administration of ibutilide (0.01 mg/kg up to 1mg). A conduction time from RA pacing spike to distal coronary sinus potential was used to measure IACT, while QRS duration of surface ECG during RV pacing was used to measure IVCT. Ibutilide prolonged RA-MAPD by 60 ms at PCL 600 ms and by 53 ms at PCL 350 ms; RV-MAPD by 48 ms at PCL 600 ms and by 55 ms at PCL 350 ms. Ibutilide did not affected RA and RV-ERP/MAPD ratio, IACT, and IVCT. Ibutilide prolongs MAPD and ERP of human atrium and ventricle without reverse use-dependency.

Action Potentials↗

PubMed2001

Does infiltration of neutrophils in peritubular capillaries indicate humoral rejection? A case displaying a characteristic lesion of a significantly high amount of neutrophils in peritubular capillaries at 1-h graft biopsy during transplant operation.

We present a case report of a 50-yr-old Japanese woman with a significant accumulation of neutrophils in the peritubular capillaries (PTC) and severe acute tubular necrosis (ATN) at 1-h allograft biopsy during transplant operation from cadaver donor after a cardiac death. Significant accumulation of neutrophils in the PTC is usually valuable diagnostically for acute humoral rejection. However, the patient showed no clinical signs of acute rejection. A second graft biopsy performed on the fifth postoperative day (POD) revealed that both infiltration of neutrophils in PTC and ATN lesions were more aggravated. Neither clinical course nor other morphological findings were compatible with humoral rejection. After the third biopsy of POD 27 revealing acute vascular rejection of moderate degree, acute rejection therapy using methylprednisolone pulse therapy and OKT-3 therapy was performed. Consequently, after a period of delayed graft function requiring haemodialysis for approximately 4 wk, graft function was restored and serum creatinine decreased to 2 mg/dL. Later, we were able obtain information from a paired graft from the same donor. Significant accumulation of neutrophils in the PTC similar to our recipient was also noted in a 1-h biopsy specimen of the paired kidney. This confirmed that the accumulation of neutrophils in the PTC noted in two recipients was transmitted from the donor kidney. The pathogenesis and clinical significance of neutrophils in the PTC has been shrouded in mystery.

Biopsy↗