Search PubMed⌕ Search

Biomedical subjects

T Miyasaka

Publications and source records attributed to T Miyasaka.

At least 19 recordsLinked to original sources
PubMed2003

Diurnal T2 value changes in the lumbar intervertebral discs.

AIM: To investigate if there is any in vivo diurnal T2 value changes in the nucleus pulposus in normal and degenerated lumbar intervertebral discs. MATERIALS AND METHODS: Eighteen volunteers (16 men, two women) with no symptoms related to lumbar disease were imaged in the morning before beginning daily work and in the evening after finishing work. Sagittal fast spin-echo T2-weighted images were obtained, following spin-echo transverse imaging for T2 analysis. RESULTS: The normal disc group (n=71) showed statistically significant diurnal T2 value changes (p<0.001), whilst the degenerating disc group (n=19) showed no significant diurnal changes. The normal disc group up to age 34 years showed statistically significant diurnal T2 value changes. However no significant changes were demonstrated after the age 35 years. CONCLUSION: Statistically significant diurnal T2 value changes in the normal lumbar intervertebral discs were demonstrated. Disappearance of the diurnal T2 value changes in the normal discs after the age 35 years was revealed for the first time and thought to be an aspect of aging, not caused by degeneration.

Adult↗
PubMed2002

Early-onset, rapidly progressive familial tauopathy with R406W mutation.

An early-onset and rapidly progressive familial tauopathy with R406W mutation is described. The patient was a 47-year-old man who first presented with psychiatric symptoms followed by overt dementia at age 52 and died 1 year later. Postmortem study revealed tangle-associated neuronal degeneration, accentuated in the medial temporal lobe. R406W mutation was determined by sequence analysis and immunocytochemically with anti-mutant tau antibody.

Age of Onset↗
PubMed2002

Postoperative nerve conduction changes after open and endoscopic carpal tunnel release.

OBJECTIVE: To assess the improvement of motor distal latency (MDL), sensory nerve conduction velocity (SCV) of the median nerve and the amplitudes of compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) in patients with idiopathic carpal tunnel syndrome subjected to surgical treatment according to the open carpal tunnel release method and the endoscopic carpal tunnel release. METHODS: Sixty-six hands of sixty-six patients were divided into two groups: the ECTR group and the OCTR group. The patients were evaluated preoperatively, and at 1, 3, 6, and 12 months postoperatively. RESULTS: Although no statistically significant difference of the recovery of MDL and the amplitude of CMAP and SNAP was detected between the two groups at any time point during follow-up, one patient in the ECTR group in whom the operation had been converted to OCTR, showed delay of MDL and decrease in the amplitude of CMAP. CONCLUSIONS: There is a risk of nerve damage in patients undergoing ECTR. Although statistical analysis suggests that nerve conduction improves by about the same degree 12 months after ECTR or OCTR, slightly faster improvement after OCTR cannot be excluded.

Action Potentials↗
PubMed2001

Characterization of human taurine transporter expressed in insect cells using a recombinant baculovirus.

A recombinant baculovirus system was used to express the human taurine transporter in Sf9 cells and characterize its mediated uptake activity. This uptake process exhibited: (i) Na(+) dependence, (ii) larger inhibition of taurine transport by competing beta-amino acids than by alpha- and gamma-amino acids, (iii) apparent Michaelis constant, K(t), for taurine transport of 1.6 +/- 0.2 microM, and (iv) a maximal velocity, V(max), of 262 +/- 18 pmol/mg protein per 15 min. Coexpression of a molecular chaperone, human calnexin, enhanced taurine transporter activity by 43%. During development of taurine transporter expression, exposure to tunicamycin (10 microg/ml) decreased taurine transport activity by 76%. The taurine transporter linked to glutathione S-transferase (GST) was expressed to determine whether this conjugate also elicits taurine transport activity. Even though transport activity was markedly decreased, its Na(+) dependence was still evident. Coexpression of calnexin enhanced expression of this conjugated transporter activity by 54%. Immunoblot analysis revealed that calnexin did not change the amount of GST-taurine transporter conjugate or its molecular mass (i.e., 58.4-68.0 kDa). However, tunicamycin decreased its molecular mass. Taken together, taurine transport activity in a baculovirus expression system has characteristics similar to its wild-type counterpart. Stimulation of transport activity by coexpression with calnexin suggests the importance of transporter folding for optimal transport activity. Glycosylation of the transporter also increases its transport activity. Finally, GST-taurine transporter conjugate usage may aid transporter purification even though its transport activity decreases.

Animals↗
PubMed2001

Molecular analysis of mutant and wild-type tau deposited in the brain affected by the FTDP-17 R406W mutation.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is a familial neurological disorder, characterized genetically by autosomal dominant inheritance, clinically by behavioral abnormalities and parkinsonism, and neuropathologically by tauopathy. Linkage analyses of affected families have led to identification of several exonic and intronic mutations in the tau gene. In this study, we analyzed molecular species of tau in the soluble and insoluble fractions of brain affected by the FTDP-17 R406W mutation. Protein chemical analysis and Western blotting using site-specific antibodies indicated that almost equal amounts of wild-type and mutant tau were present in the Sarkosyl-insoluble fraction of the R406W brain. Consistent with this, wild-type and mutant tau colocalized in neurofibrillary tangles in the frontal cortex and hippocampus of the R406W brain. In contrast to soluble R406W tau, which was less phosphorylated than soluble wild-type tau, the Sarkosyl-insoluble mutant tau was highly phosphorylated as well as the insoluble wild-type tau.

Aged↗
PubMed2001

The proton uptake channel of bacteriorhodopsin as studied by a photoelectrochemical method.

A series of the mutant proteins (D96N, D96N/D85N, D115N, L93T, T46V, V49A) where the residues are located at the cytoplasmic domain of bacteriorhodopsin (bR) were studied photoelectrochemically and their photocurrent response characteristics at the electrode/electrolyte interface were compared with those of the wild-type bR. While the wild-type bR of normal proton pumping activity yields symmetrical cathodic (positive) and anodic (negative) responses, corresponding to proton release and proton uptake, respectively, these mutants, with the exception of D115N, showed diminished amplitudes in the negative response. This indicates retardation of proton translocation from the cytoplasmic surface to the retinal Schiff base. The mutation that gave the strongest influence on the negative response was D96N while moderate influence was obtained with L93T, T46V, and V49A. These results suggest that residues other than D96 also participate in the cytoplasmic proton uptake channel, either by interacting with D96 directly or by forming a hydrogen-bonded network with water molecules. The D96N/D85N double mutant yielded little response at neutral pH, but the response was partially recovered by addition of azide, while it was fully recovered in the single mutant D96N. The D115N mutant showed the response profile that closely resembles the wild-type, indicating that D115 is not crucially involved in the event of proton transfer relay at the cytoplasmic region. It was also found that every mutant in this study releases protons prior to uptake at the other membrane surface, as does the wild-type.

Azides↗
PubMed2001

Platelet-derived growth factor is involved in the augmentation of airway responsiveness through remodeling of airways in diesel exhaust particulate-treated mice.

BACKGROUND: Thickening of the region adjacent to the basement membrane is a key component of the remodeling of the asthmatic airway and is caused by collagen deposition in the region. OBJECTIVE: We sought to clarify the role of platelet-derived growth factor (PDGF), a competence factor of fibroblast, in the enhanced airway responsiveness and remodeling in a murine model. METHODS: Diesel exhaust particulates (DEPs) were administered intranasally every other day for 2 weeks with or without anti-PDGF-beta neutralizing antibody or goat IgG. Pulmonary function was then analyzed by using whole-body plethysmography before and after acetylcholine inhalation. RESULTS: Anti-PDGF-beta neutralizing antibody significantly inhibited both the elevation of airway resistance elicited by 1.25 and 2.5 mg/mL acetylcholine and the increase in the airway wall thickening induced by DEPs. In addition, bronchoalveolar lavage fluid cell analysis revealed that anti-PDGF-beta neutralizing antibody did not affect cellular infiltration at the airways. CONCLUSION: PDGF plays an important role in the process of remodeling brought about by DEP exposure in mice.

3T3 Cells↗
PubMed2001

Selective deposition of mutant tau in the FTDP-17 brain affected by the P301L mutation.

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is a familial neurological disorder exhibiting autosomal dominant inheritance. Linkage analyses have led to the identification of many exonic and intronic mutations in the tau gene in affected families. Because FTDP- 17 causes extensive neuronal loss and intracellular tau deposits in affected regions, investigation of this disease should provide an important insight into the significance of tau deposits leading to neurodegeneration. Using site-specific antibodies that distinguish between wild-type and mutant tau, we have analyzed the proportions of wild-type and mutant tau in the soluble and insoluble fractions of the P301L brain. Western blotting showed that mutant tau was selectively deposited in the Sarkosyl-insoluble fraction. Consistent with this, immunocytochemistry showed that intraneuronal tau deposits consisted exclusively of mutant tau. In one case in which abundant senile plaques occurred, in addition to mutant tau, small amounts of wild-type tau were also deposited. On the other hand, the protein levels of mutant tau in the soluble fraction were selectively decreased despite no detectable decrease in the levels of mutant tau mRNA.

Aged↗
PubMed2001

Electrochemical behavior of catechol and 3,4-dihydroxytoluene in acetonitrile at a platinum-disk electrode modified with a tyrosinase containing polyacrylamide film.

A modified platinum-disk electrode coated with a non-plasticized polyacrylamide (PAA) membrane was used to study electrochemically an enzymatic reaction between tyrosinase in the PAA membrane and catechol and 3,4-dihydroxytoluene in acetonitrile (AN). Tyrosinase, a hydrophilic biofunctional material, was immobilized in the thin PAA membrane, which adhered to the platinum-disk electrode and was stable in AN. The enzymatic activity of tyrosinase in the PAA membrane to the above substrates in AN was confirmed by cyclic voltammetry and amperometry. The apparent maximum velocities (Vmaxapp) and the apparent Michaelis constants (Kmapp) were determined from the amperometric results; the apparent turnover numbers were also determined. The reduction potentials of the substrates were reported vs. the cathodic peak potential of ferrocene in AN to improve the reliability of the potential data and to make possible a comparison of the potentials in different solvents. The electrochemical system discussed in this report can be used for tracing enzymatic reactions with substrates dissolving in aprotic dipolar solvents and for investigating solvent effects on enzymatic activities.

Acetonitriles↗
PubMed2000

Induction of apoptosis in bronchial eosinophils: beneficial or harmful?

BACKGROUND: Prominent eosinophil infiltration takes place in asthmatic bronchi, and damages bronchial epithelial cells. AIM: This study was designed to investigate whether induction of apoptosis in infiltrated cells in the airways is beneficial or harmful. METHODS: A/J mice, which are genetically predisposed to be hyperresponsive to acetylcholine, were immunized with ovalbumin (OA) and alum. Thereafter, they were subjected to a 2-week regimen of OA inhalation, during which they were also administered either hamster anti-mouse Fas monoclonal antibody or hamster IgG (sham control) intranasally. Pulmonary function was then analyzed using whole-body plethysmography. RESULTS: Inhalation of OA increased both airway responsiveness to acetylcholine and infiltration of eosinophils. Administration of anti-Fas antibody induced apoptosis in the infiltrating eosinophils and abolished the increase in airway responsiveness to acetylcholine. CONCLUSION: Induction of apoptosis in eosinophils infiltrating asthmatic bronchi has a beneficial effect on airway hyperresponsiveness.

Acetylcholine↗
PubMed2000

A diffuse alveolar hemorrhage in a human T-lymphotropic virus type I carrier with acute cerebellar ataxia and interstitial pneumonitis: an autopsy case report.

A 76-year-old HTLV-I-positive male with acute cerebellar ataxia was suffering from dyspnea on exertion. Chest CT suggested interstitial pneumonitis. Methylprednisolone pulse therapy improved his symptoms and chest CT findings. Twelve months after discharge, when the prednisolone dose was tapered to 5 mg every other day, his lung lesion recurred. The lesion responded initially to steroid therapy. However, hypoxemia intractable to steroid pulse therapy developed and the patient died of respiratory failure. The autopsy revealed diffuse alveolar hemorrhage with no finding of vasculitis. This is the first case report of diffuse alveolar hemorrhage in an HTLV-I carrier.

Acute Disease↗
PubMed2000

Effect of binary and ternary filler mixtures on the mechanical properties of composite resins.

The mechanical strength of experimental light cure composites containing binary filler mixtures with various combinations of irregular and spherical macrofillers in various mixes, and the microfilled ternary system fillers were measured. The compressive strength of the binary mixtures between different shaped fillers was not related to mixing ratios, although it significantly increased as the filler size decreased. The mixing ratio was immaterial within the irregular filler mixture. The compressive strength of the binary mixtures within the spherical fillers increased as the mixing ratio increased while the filler size was relatively large, then the mixing ratio became insignificant as the filler size decreased under 1.4 microns. The compressive strength of the microfilled ternary fillers increased with the decrease in the macrofiller size and with the increase in the mixing ratio. A large diametrical tensile strength was found in several microfilled ternary mixtures containing different shaped macrofillers.

Analysis of Variance↗
PubMed1999

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal.

Ku antigen is a complex of Ku70 and Ku80 subunits and plays an important role in not only DNA double-strand breaks (DSB) repair and V(D)J recombination, but also in growth regulation. Ku is generally believed to always form and function as heterodimers on the basis of in vitro observations. Here we demonstrate that the localization of Ku80 does not completely coincide with that of Ku70. Ku70 and Ku80 were colocalized in the nucleus in the interphase but not in the late telophase/early G1 phase of the cell cycle. Since the in vivo function of Ku might be partially regulated by the control of its transport, we attempted to investigate the molecular mechanisms underlying the nuclear translocation of Ku. The nuclear translocation of Ku80 started during the late telophase/early G1 phase after the nuclear envelope was formed and this was preceded by the nuclear translocation of Ku70. Furthermore, we found that the Ku80 protein was transported to the nucleus without heterodimerization with Ku70. To understand in detail the mechanism of transport of Ku80, we attempted to identify the nuclear localization signal (NLS) of Ku80 and defined to a region spanning nine amino acid residues (positions 561 - 569). The Ku80 NLS was demonstrated to be mediated to the nuclear rim by two components of PTAC58 and PTAC97. All these findings support the idea that Ku80 can translocate to the nucleus using its own NLS independent of the translocation of Ku70.

Amino Acid Sequence↗
PubMed1999

The nuclear localization signal of the human Ku70 is a variant bipartite type recognized by the two components of nuclear pore-targeting complex.

Ku protein is a complex of two subunits, Ku70 and Ku80. Ku is suspected to participate in both DNA double-strand break repair and transcription. Since both of these processes take place in the cell nucleus, we have been investigating the subcellular localization and nuclear transport of Ku proteins. In the present study, we analyzed the subcellular localization and nuclear localization signal (NLS) of Ku70. Fusion proteins of Ku70 and green fluorescent protein (GFP) transiently expressed in cells were clearly localized in the nuclei of interphase cells. Ku70 staining was distributed throughout both the nucleus and the cytoplasm in late telophase to early G1 phase cells. The NLS of Ku70 was located at the region composed of 18 amino acid residues (positions 539 to 556). This region overlapped with the Ku80-independent DNA-binding domain reported previously. The Ku70 NLS consisted of two basic subregions and a nonbasic intervening region. All the subregions were necessary for complete NLS activity. The amino acids in the nonbasic intervening region of Ku70 might be important for full NLS activity not only to provide sufficient length between the two separated clusters of basic amino acids but also to have an adequate amino acid sequence. All of the basic amino acid residues in the basic subregions were conserved among mammalian and avian homologues, confirming their importance in the nuclear translocation of Ku70. The structure of the Ku70 NLS resembled the consensus of a bipartite-type NLS. The Ku70 NLS was mediated to target to the nuclear rim by two components of the nuclear pore-targeting complex, PTAC58 and PTAC97.

Amino Acid Sequence↗
PubMed1999

Diesel exhaust particulate induces airway hyperresponsiveness in a murine model: essential role of GM-CSF.

BACKGROUND: Inhaled pollutants were recently shown to be responsible for an increased incidence of airway allergic diseases, including asthma. A common feature of all forms of asthma is airway hyperresponsiveness. OBJECTIVE: Our purpose was to elucidate the effects of diesel exhaust particulate (DEP), one of the most prevalent inhaled pollutants, on airway responsiveness. METHODS: A/J and C57Bl/6 mice were used; the former are genetically predisposed to be hyperresponsive to acetylcholine, whereas the latter are not. DEP was administered intranasally for 2 weeks, after which pulmonary function was analyzed by whole-body plethysmography. RESULTS: Intranasal administration of DEP increased airway responsiveness to acetylcholine in both A/J and C57Bl/6 mice and induced displacement of ciliated epithelial cells by mucus-secreting Clara cells. The effect was mediated by M(3) muscarinic receptors. Acetylcholine-evoked bronchial constriction was reversed by administration of terbutaline, a beta(2)-adrenergic antagonist, which is also characteristic of human asthma. Intranasal administration of antibody raised against GM-CSF abolished DEP-evoked increases in airway responsiveness and Clara cell hyperplasia. The antibody raised against IL-4 also inhibited DEP-evoked increases in airway responsiveness. However, it was to a lesser extent compared with antibody against GM-CSF. In addition, DEP stimulated GM-CSF messenger RNA expression in the lung. CONCLUSION: DEP induces airway hyperresponsiveness by stimulating GM-CSF synthesis.

Acetylcholine↗
PubMed1999

Accompanying arteries of the lesser saphenous vein and sural nerve: anatomic study and its clinical applications.

The arteries adjacent to the lesser saphenous vein and sural nerve were investigated in 10 fresh cadavers that had been systemically injected with a lead oxide-gelatin mixture. The accompanying arteries were found to lie along the lesser saphenous vein and sural nerve and to nourish the skin through venocutaneous and neurocutaneous perforators. On the basis of the anatomy of these accompanying arteries, the lesser saphenous venoadipofascial (VAF) pedicled fasciocutaneous flap and the lesser saphenous-sural veno-neuro adipofascial (V-NAF) pedicled fasciocutaneous flap have been developed and applied to 23 cases of various reconstructions of the lower extremity with proximal and distal bases. Survival of the flaps has been extremely good, and the flaps have been clinically useful.

Adult↗