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Biomedical subjects

S Yasui

Publications and source records attributed to S Yasui.

At least 19 recordsLinked to original sources
PubMed2003

A proposal on the hard tissue remineralization in osteoarthritis of the knee joint investigated by FT-IR spectrometry.

An investigation was performed on hard tissues of the affected area in the cases of osteoarthritis of the knee joint by using Fourier transform infrared spectroscopy (FT-IR) to obtain the information on components and characteristics of the compounds in the hard tissues at the molecular level. Biological specimens used were: normal cortical bone, normal cancellous bone, sclerotic area of the affected site (subchondral bone), osteophyte and cartilage of the affected joint. FT-IR spectra of these specimens were measured and spectroscopic characteristics of various types of hard tissues were quantified. As the result of the analysis, signal ratio of PO4(3-) to amide I (PO4(3-)/amide I) was 0 in cartilage, and the ratio was at the highest in normal cortical bone of the ulna, being as high as 1.82. The signal ratio of the sclerotic area of the affected site was 1.69, and this was higher than the values in osteophyte (1.44) or cancellous bone of the tibia (1.61). It is inferred from these data that the degree of remineralization was considerably higher in osteoarthritis of the knee joint. On the other hand, in the osteophyte, which is frequently seen in the radiography of osteoarthritis, it was 1.44 for the attached osteophyte and 1.37 for the detached osteophyte, and these values were lower compared with the values in the sclerotic area of the affected site (1.69). From these results, it appears that remineralization of mineral components is very likely to occur under the acidic conditions in the articular region in this disease. We propose that the mechanism of hard tissue formation in the knee joint of osteoarthritis is a form of remineralization.

Aged↗
PubMed2001

Comparative in-vitro activity of carbapenem antibiotics against respiratory pathogens isolated between 1999 and 2000.

We investigated the antibacterial activity of 12 antibiotics, inclusive of four carbapenems, against 167 strains of respiratory pathogens isolated between 1999 and 2000. Thirty strains of methicillin-susceptible Staphylococcus aureus (MSSA), 28 strains of methicillin-resistant S. aureus (MRSA), 11 strains of penicillin-susceptible Streptococcus pneumoniae (PSSP), 29 strains of penicillin-resistant S. pneumoniae (PRSP), 30 strains of Pseudomonas aeruginosa, 14 strains of Moraxella catarrhalis, and 25 strains of Haemophilus influenzae were examined. The minimum inhibitory concentration (MICs)50/90 (microg/ml) of imipenem, panipenem, meropenem, and biapenem against the clinical isolates obtained between 1999 and 2000 were: 0.06/0.25, 0.12/0.25, 0.12/0.25, and 0.12/0.25, respectively, against MSSA; 16/32, 16/32, 16/32, and 8/32 against MRSA; < or = 0.015/0.06, < or = 0.015/0.03, 0.03/0.12, and < or = 0.015/0.06 against PSSP; 0.12/0.25, 0.03/0.06, 0.25/0.5, and 0.12/0.25 against PRSP; 1/8, 2/8, 0.5/2, and 2/16 against P. aeruginosa; 0.06/0.06, 0.03/0.06, < or = 0.015/0.06, and 0.06/0.12 against M. catarrhalis; and 1/4, 1/4, 0.12/0.25, and 2/4 against H. influenzae. A comparison of the antibacterial activity of the four carbapenems with that found in our previous studies showed no significant difference in the susceptibility of clinical isolates, except for a slight decrease in the susceptibility of MSSA. Carbapenems have remained effective for severe infections. The MIC data showed that imipenem and panipenem were more active than meropenem and biapenem against gram-positive bacteria, and that meropenem and biapenem were more active than imipenem and panipenem against gram-negative bacteria. As only meropenem had an MIC90 below the breakpoint of pneumonia against all species except MRSA, meropenem was considered to be the most potent of the four carbapenems studied.

Anti-Bacterial Agents↗
PubMed2001

85Kr measurement system for continuous monitoring at the Meteorological Research Institute, Japan.

A 85Kr measurement system for continuous monitoring based principally on the BfS-IAR method (activity measurement of 85Kr by gas counting coupled with gas chromatographic separation, using pure CH4 as carrier and Counting gas) was implemented for the first time in Japan. In this paper, a detailed description of the system and procedures is given and the inter-comparison results of our system with the BfS-IAR system are presented. A consistent temporal concentration change with high accuracy and consistency of the respective data with the BfS-IAR data (maximum difference of 5%) were achieved with the Meteorological Research Institute (MRI) system, which shows that the system is valid and reliable for the purpose of background monitoring for 85Kr in air. Also, the 85Kr monitoring record at the MRI during 1995-2001 is described. The record distinctively shows the Northern Hemispheric background 85Kr concentrations at the mid-latitude and the elevated concentrations affected by the operation of a nuclear fuel reprocessing plant in Tokai-mura, Ibaraki. Japan.

Air Pollutants, Radioactive↗
PubMed2001

Serine proteases increase oxidative stress in lung cells.

Several serine proteases are directly cytotoxic. We investigated whether the cytotoxic effects of proteases are associated with increased levels of reactive oxygen species (ROS) in cells. We found that treatment of lung fibroblasts or bronchial epithelial cells with relatively high concentrations (0.1--100 U/ml) of neutrophil elastase, trypsin, and Pronase increased ROS levels in the mitochondria and cytoplasm. The protease-induced increase in ROS was associated with oxidative cellular injury as determined by generation of 8-hydroxy-2'-deoxyguanosine and malonaldehyde plus 4-hydroxyalkenal. The protease-induced increase in ROS was not merely due to cell detachment because the proteases also caused an increase in ROS in suspended cells, which precluded attachment to the extracellular matrix. The protease-induced increase in ROS appears to contribute to cytotoxicity because cell death induced by proteases was attenuated by treatment with catalase, a decomposer of H(2)O(2), and accelerated by treatment with aminotriazole, a catalase inhibitor. These results suggest that several proteases increase oxidative stress, indicating a direct interaction between proteases and ROS in mediating cytotoxicity.

Bronchi↗
PubMed2000

Quenching of a photosensitized dye through single-electron transfer from trivalent phosphorus compounds

Various types of trivalent phosphorus compounds 1 undergo single-electron transfer (SET) to the photoexcited state of rhodamine 6G (Rho+*) in aqueous acetonitrile to quench the fluorescence from Rho+*. The rate constants kp for the overall SET process were determined by the Stern-Volmer method. The rate is nearly constant at a diffusion-controlled limit in the region of E1/2(1) < 1.3 V (vs Ag/Ag+), whereas log kp depends linearly on E1/2(1) in the region of E1/2(1) > 1.3 V, the slope of the correlation line being -alphaF/RT with alpha = 0.2. The potential at which the change in dependence of log kp on E1/2(1) occurs (1.3 V) is in accordance with the value of E1/2(Rho+*) (1.22 V) that has been obtained experimentally. Thus, the SET step is exothermic when E1/2(1) < 1.3 V and endothermic when E1/2(1) > 1.3 V. The alpha-value (0.2) obtained in the endothermic region shows that the SET step from 1 to Rho+* is irreversible in this region. Trivalent phosphorus radical cation 1*+ generated in the SET step undergoes an ionic reaction with water in the solvent rapidly enough to make the SET step irreversible. In contrast, the SET from amines 2 and alkoxybenzenes 3 to Rho+* is reversible when the SET step is endothermic, meaning that the radical cations 2*+ and 3*+ generated in the SET step undergo rapid "back SET" in the ground state to regenerate 2 and 3.

Journal Article↗
PubMed2000

The Fas/Fas-ligand system is not required for bleomycin-induced pulmonary fibrosis in mice.

Recent studies suggest that Fas-Fas-ligand (FasL) interactions play an important role in the development of lung injury and fibrosis. However, evidence to support this concept is still indirect. To determine whether Fas-FasL interaction is required for the development of bleomycin-induced pulmonary fibrosis in mice, we used Fas-deficient (lpr) and FasL-deficient (gld ) mice as animal models. After intratracheal instillation of bleomycin, we examined the lungs of mice through bronchoalveolar lavage, histologic studies, DNA nick-end labeling, and hydroxyproline assay. The development of cellular infiltrates, bronchiolar and alveolar epithelial apoptosis, and fibrosis following bleomycin instillation in the lungs in lpr mice and gld mice was similar to their development in wild-type mice. The results of this study show that bleomycin-induced pulmonary fibrosis does not require Fas-FasL interaction, and that epithelial cell apoptosis after bleomycin exposure is mediated by Fas-independent pathways.

Animals↗
PubMed1999

Effects of nitric oxide, light adaptation and APB on spectral characteristics of H1 horizontal cells in carp retina.

The spectral characteristics of cone-driven horizontal cells of H1 subtype (H1 HCs) receiving main synaptic input from red-sensitive cones were studied in light- and dark-adapted retinae of carp. The spectral sensitivity profile of H1 HCs in dark-adapted retinae was practically the same as the absorption spectrum of red-sensitive cones. Light-adaptation decreased the sensitivity preferentially in the short-wavelength (blue/green) region, resulting in a relative enhancement of the 617 nm peak. Application of nitric oxide (NO) donors, sodium nitroprusside (SNP) and S-nitrosoglutathione (SNOG or GSNO), or dopamine to dark-adapted retinae decreased the sensitivity preferentially in blue/green region, an effect similar to that of light-adaptation. Application of haemoglobin (Hb, an NO scavenger) or 2-amino-4-phosphonobutyrate (APB, a metabotropic glutamate receptor agonist), to light-adapted retinae increased the sensitivity preferentially in the blue/green region, an effect similar to dark-adaptation. The photoresponses of H1 HCs were univariant in dark-adapted retinae as well as Hb-treated light-adapted retinae. In light-adapted retinae with normal Ringer, however, the univariance did not hold. These results suggested that the photoresponses of H1 HCs to short-wavelength stimuli contain a depolarising (sign-reversing) component, which can be activated by light-adaptation or application of NO and dopamine, and inactivated by dark-adaptation or deprivation of NO or application of APB.

Adaptation, Ocular↗
PubMed1999

Red blood cells inhibit apoptosis of human neutrophils.

Oxidative stress has been implicated in the triggering of apoptosis in neutrophils. Because red blood cells (RBCs) are well known to scavenge oxidants including H2O2, we tested the hypothesis that RBCs inhibit apoptosis of neutrophils by reducing intracellular oxidative stress. Apoptosis of neutrophils was evaluated by light microscopy and DNA gel electrophoresis. We found that coculture with RBCs protected against neutrophil apoptosis. Neither physical contact between RBCs and neutrophils nor the cellular integrity of RBCs was required to protect against neutrophil apoptosis. Neutrophil apoptosis was promoted by exogenous H2O2 but suppressed by catalase, indicating a role for H2O2 as a mediator of apoptosis. The protective effect of RBCs against apoptosis was due to catalase and glutathione metabolism because blocking of these antioxidant systems in RBCs attenuated the protective effect of RBCs. These results suggest that neutrophils are protected against apoptosis in the circulation.

Apoptosis↗
PubMed1999

Role of p38-mitogen-activated protein kinase in spontaneous apoptosis of human neutrophils.

Neutrophils constitutively undergo apoptosis at both normal and inflamed sites: an important process that limits the toxic potential of the neutrophil. However, the signal pathway for neutrophil apoptosis is currently unknown. In this study, we evaluated the role of p38-mitogen-activated protein kinase (MAPK) in the spontaneous apoptosis of neutrophils in vitro. We found that p38-MAPK was constitutively tyrosine phosphorylated and activated during spontaneous apoptosis of neutrophils. Inhibition of p38-MAPK by SB203580 and an antisense oligonucleotide delayed apoptosis by approximately 24 h. The antioxidants catalase and N-acetylcysteine delayed neutrophil apoptosis, but failed to inhibit phosphorylation and activation of p38-MAPK. Granulocyte-macrophage CSF and anti-Fas Ab, which altered the rate of apoptosis, did not affect phosphorylation and activation of p38-MAPK. These results suggest that the constitutive phosphorylation and activation of p38-MAPK are involved in the program of spontaneous apoptosis in neutrophils.

Antioxidants↗
PubMed1999

H2O2 induces apoptosis in bovine tracheal epithelial cells in vitro.

Oxidants play an important role in the pathogenesis of various airway diseases. Oxidants have been shown to induce two distinct types of cell death, i.e., apoptosis and necrosis. However, whether oxidants induce apoptosis in airway epithelial cells remains unclear. To address this question, we evaluated the effect of H2O2 exposure on bovine tracheal epithelial cells cultured under different conditions. When tracheal epithelial cells were isolated and exposed to H2O2 in suspension cultures, they underwent apoptosis as demonstrated by characteristic ultrastructural changes and DNA fragmentation. Interestingly, apoptosis occurred in single cells but not in aggregated cells. In addition, apoptosis was seen in many ciliated and in fewer mucous cells. When tracheal epithelial cells were allowed to attach to the substrate and grow, they became resistant to apoptosis induced by H2O2. These results suggest that H2O2 can induce apoptosis in airway epithelial cells.

Animals↗
PubMed1999

An MR image of spinal cord sarcoidosis.

We present a case of spinal cord sarcoidosis with a unique magnetic resonance imaging (MRI) finding. MRI of the cervical spine revealed an unusual lesion of low signal intensity on T2-weighted image at the core of the lesion surrounded by high signal intensity. T1-weighted gadolinium enhanced image showed a high signal at the core lesion. Low signal intensity on T2-weighted image in the case was suggested to be due to hemosiderin deposition. Steroid therapy dramatically improved clinical symptoms with a marked reduction of peripheral T2 high intensity area and the core lesion size detected by gadolinium enhancement.

Aged↗
PubMed1999

Thiol depletion induces apoptosis in cultured lung fibroblasts.

Thiol antioxidants are implicated in the protection of cells from oxidative injury. We studied the role of thiols in the regulation of apoptosis in cultured lung fibroblasts. Thiol depletion by culturing fibroblasts in cystine-free medium or with thiol-depleting agents induced oxidant accumulation and cell death by apoptosis. The cell death was prevented by the antioxidants ascorbic acid (AA) and catalase. Thiol depletion also induced leukotriene (LT) C4, LTD4, and LTE4 production and selective phosphorylation of p38-mitogen-activated protein kinase (MAPK) and its nuclear substrate ATF2. LT production and p38-MAPK phosphorylation were required for induction of apoptosis because thiol depletion-induced apoptosis was completely blocked by the 5-lipoxygenase inhibitor AA861, the LT antagonists FPL55712 and ONO1078, and the p38-MAPK inhibitor SB203580. LT production was inhibited by AA and p38-MAPK phosphorylation was inhibited by AA, AA861, and FPL55712. In an in vitro scratch wound model, repopulating fibroblasts at the wound margin, but not quiescent cells at the intact site, selectively underwent thiol depletion- induced apoptosis that was completely blocked by AA861, FPL55712, and SB203580. Thus, thiol depletion induces apoptosis through an ordered pathway involving oxidant accumulation, LT production, and p38-MAPK activation. Apoptosis of wound fibroblasts may be responsible for impaired wound healing in various organs, including the lung.

Apoptosis↗
PubMed1999

Kaposi's sarcoma-associated herpesvirus infection in the lung in multicentric Castleman's disease.

A 32-year-old female was admitted for evaluation of multiple infiltrates on a chest radiograph. A diagnosis of multicentric Castleman's disease was made on the basis of typical clinical manifestations. Transbronchial lung biopsy (TBLB) revealed histological findings reported in lymphocytic interstitial pneumonia. Both the polymerase chain reaction and in situ hybridization with a probe specific for Kaposi's sarcoma-associated herpesvirus (KSHV) sequences demonstrated the presence of KSHV in the TBLB sample.

Adult↗
PubMed1999

[Patients with cardiomyopathy screened by an annual health check].

We identified 12 new cases of hypertrophic cardiomyopathy (HCM) and 3 new cases of dilated cardiomyopathy (DCM with echocardiography) in 72980 (aged 18-85 years, 43.1 +/- 14.1) industrial workers during an annual health check from April to October in 1996. Two of 3 patients with DCM were males, 21 and 25 years of age. No patients had symptoms. ST-T abnormalities by electrocardiography were found in 87% (13/15) of patients with cardiomyopathy and left ventricular hypertrophy (LVH) in 53% (8/15). Our findings suggest that echocardiography is important in mass screening for early detection of asymptomatic cardiomyopathy in middle-aged as well as young patients with ST-T abnormalities.

Adolescent↗
PubMed1999

[In vitro activity of biapenem (BIPM) against clinically isolated respiratory pathogens in 1996-1998].

The in vitro antibacterial activity of biapenem (BIPM), a new carbapenem antibiotic, was compared with those of imipenem (IPM), panipenem (PAPM), meropenem (MEPM), ceftazidime (CAZ) and piperacillin (PIPC) against 280 isolates of 9 respiratory pathogens. The MIC90s of biapenem (BIPM) for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Haemophilus influenzae were 0.12, 32, 0.25, 0.06, 4 and 8 micrograms/ml, respectively. In comparison with other antibiotics, the activity of biapenem (BIPM) for P. aeruginosa was as potent as meropenem (MEPM), but for H. influenzae it was slightly less than those of other antibiotics, and for other respiratory pathogens it was as potent as those of other antibiotics. The MIC90s of biapenem (BIPM) for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Serratia marcescens were 0.06, 1, 1, 0.5 microgram/ml, respectively, and which were equal to or somewhat lower than those of other antibiotics. Biapenem (BIPM) showed strong activity against Gram-positive and Gram-negative pathogens, especially P. aeruginosa in general. Based on these results, biapenem (BIPM) is seemed to be highly useful antibiotic for the treatment of respiratory infections with several organism.

Bacteria↗
PubMed1998

Modulation of chromatic difference in receptive field size of H1 horizontal cells in carp retina: dopamine- and APB-sensitive mechanisms.

Chromatic aspects of receptive field size in the H1 horizontal cell syncytium of the carp retina were investigated using spectral photostimuli (blue or red) presented in the form of either a pair of a small spot and annulus, or a narrow moving slit. In the light-adapted retina, the receptive field for the blue stimulus was found to be significantly smaller than that for the red, i.e. there was a chromatic difference in the receptive field size. During the course of dark adaptation, the overall receptive field size increased, but the chromatic difference decreased. Immediately after adaptation to bright light, the receptive field sizes were reduced significantly, but the chromatic difference increased, mainly due to a greater reduction in the receptive field for the blue stimulus. Application of dopamine (5 microM) to a dark-adapted retina gradually decreased the receptive field size for both colours, but the chromatic difference became larger, again due to a greater reduction in the receptive field size for the blue stimulus. 2-Amino-4-phosphonobutyrate (APB) applied to light-adapted retinae at a working concentration of 1 mM, greatly expanded the receptive field size and suppressed the chromatic difference due to the effect being greater for the receptive field for the blue stimulus. The effect of APB was slow and cumulative. On the other hand, intracellular injection of cGMP or dibutyryl-cGMP increased the chromatic difference in the receptive field size. It is suggested (i) that the chromatic difference in the receptive field size could be due to a cGMP-coupled, conductance-decreasing receptor mechanism activated by APB; and (ii) that the mechanism is associated with short-wavelength sensitive cone input to the H1 cells and operates in the light-adapted state of the retina.

Adaptation, Ocular↗