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Biomedical subjects

K Hashimoto

Publications and source records attributed to K Hashimoto.

At least 73 records · Page 4Linked to original sources
PubMed2003

[Left ventricular papillary fibroelastoma associated with chief complaints of palpitation, general fatigue, and feverish].

Papillary fibroelastoma is one of the commonest benign tumor in the heart. In almost all of cases, symptoms never develop and the tumors are usually discovered coincidentally. Even though papillary fibroelastoma is a benign tumor, surgical extirpation is usually indicated for reason of productive serious complications. The tumors may cause left ventricular outflow obstruction, cerebral embolic infarction, myocardial infarction and even sudden death. The case we reported here is unusual case, because the patient developed symptoms and complaints such as palpitation, feverish and general fatigue. We measured tumor markers, interleukin 6, serotonin and histamine, but none of those was elevated in the blood samples. Surgical removal of the tumor attached to the base of posterior papillary muscle was carried out without causing mitral incompetence, and the pathological findings were compatible with papillary fibroelastoma. After the operation, the both symptoms and complaints disappeared unexpectedly.

Fatigue↗
PubMed2002

Crystallization and preliminary X-ray analysis of the trehalose/maltose ABC transporter MalFGK2 from Thermococcus litoralis.

Trehalose and maltose uptake in the hyperthermophilic archaeon Thermococcus litoralis is mediated by an ABC transport system. The heterotetrameric transport complex MalFGK(2), consisting of two membrane-spanning subunits and two copies of an ATP-binding cassette protein, has been crystallized. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 106.5, b = 150.5, c = 170.1 A, beta = 107.8 degrees. A native data set has been obtained at a resolution of 5 A.

Archaeal Proteins↗
PubMed2002

Electrically controlled nuclear spin polarization and relaxation by quantum-Hall states.

We study interactions between electrons and nuclear spins by using the resistance ( Rxx) peak which develops near the Landau-level filling factor nu = 2/3 as a probe. Temporarily tuning nu to a different value, nu(temp), with a gate demonstrates that the Rxx peak regenerates even after complete depletion ( nu(temp) = 0), while it rapidly relaxes on either side of nu(temp) = 1. This indicates that the nu = 2/3 domain morphology is memorized by the nuclear spins which can be rapidly depolarized by Skyrmions. An additional enhancement in the nuclear spin relaxation around nu = 1/2 and 3/2 suggests a Fermi sea of partially polarized composite fermions.

Journal Article↗
PubMed2002

Low-dose ACTH therapy for West syndrome: initial effects and long-term outcome.

BACKGROUND: Most Japanese pediatric neurologists attempt other treatments before using adrenocorticotropic hormone (ACTH) therapy for West syndrome (WS), and even then, they use only a low-dose synthetic ACTH to avoid serious adverse effects. In this multi-institutional study, the authors analyzed the initial effects, adverse effects, and long-term outcome in patients treated with low-dose synthetic ACTH in Japan. METHODS: The medical records of 138 patients with WS, who were treated with low-dose synthetic ACTH therapy for the first time at the authors' institutions between 1989 and 1998, were analyzed. RESULTS: At the end of ACTH therapy, excellent effect on seizures was noted in 106 of 138 (76%) patients, good effect in 23 (17%), and poor effect in 9 (7%). Initial effects on EEG were excellent in 53 of 138 (38%) patients, good in 76 (55%), and poor in 9 (7%). As for seizure prognosis at the time of follow-up, 51 of 99 (52%) patients were seizure-free, whereas 48 (48%) patients had seizures. Mental outcome was normal in 6 of 98 (6%) patients, mild mental retardation in 16 (16%), moderate mental retardation in 26 (27%), and severe mental retardation in 50 (51%). The initial effects of ACTH on seizures and long-term outcome were not dose dependent (daily dosage 0.005 to 0.032 mg/kg, 0.2 to 1.28 IU/kg; total dosage 0.1 to 0.87 mg/kg, 4 to 34.8 IU/kg). The severity of adverse effects correlated with total dosage of ACTH, and the severity of brain volume loss due to ACTH correlated well with the daily dosage and total dosage of ACTH. CONCLUSION: Low-dose synthetic ACTH therapy is as effective for the treatment of WS as the higher doses used in previous studies. The dosage of synthetic ACTH used in the treatment of WS can be decreased as much as possible to avoid serious adverse effects.

Brain↗
PubMed2002

Emergence of a functional coupling between inositol-1,4,5-trisphosphate receptors and calcium channels in developing neocortical neurons.

Cortical pyramidal neurons are considered to be less excitable in the immature cortex than in adults. Our previous report revealed that a negative feedback regulation of membrane excitability is highly correlated with a novel form of calcium release from inositol-1,4,5-trisphosphate (IP(3))-sensitive calcium stores (IP(3)-assisted calcium-induced calcium release) in neocortical pyramidal neurons under muscarinic cholinergic activation. As a step to understand the ground for the low membrane excitability in immature tissue, we examined development of IP(3)-assisted calcium-induced calcium release. In visual cortex neurons from 'juvenile' rats (2-3 weeks of age), an enhancement of spike-frequency adaptation occurred at high spike-frequencies (16-22 Hz), whereas the reduction was observed at low frequencies (6-10 Hz). IP(3)-assisted calcium-induced calcium release occurred at the higher frequencies only. In 'early' postnatal tissue (1 week of age), by contrast, at neither high nor low frequencies did this form of calcium release occur, and muscarinic cholinergic activation always induced a reduction of spike-frequency adaptation at any spike-frequencies. The mechanism for the failure of induction of IP(3)-assisted calcium-induced calcium release in 'early' postnatal tissue was investigated. Both an ample supply of calcium influx, elicited by higher frequency spike trains, and a supplementary injection of IP(3) through whole-cell pipets, combined together or applied alone, failed to enable IP(3)-assisted calcium-induced calcium release in 'early' postnatal tissue. Muscarinic cholinergic activation alone induced a conventional IP(3)-induced calcium release similar to that observed in neurons from 'juvenile' tissue. Together, it is most likely that functional IP(3)Rs and calcium channels are already present and functional, but are not yet adequately assembled to allow IP(3)-assisted calcium-induced calcium release in cortical pyramidal neurons from rats of 1 week old.

Action Potentials↗
PubMed2002

A distinct form of calcium release down-regulates membrane excitability in neocortical pyramidal cells.

We reported a novel type of calcium release from inositol-1,4,5-trisphosphate (IP(3))-sensitive calcium stores synergistically induced by muscarinic acetylcholine receptor (mAchR)-mediated increase in IP(3) and action potential-induced calcium influx (IP(3)-assisted calcium-induced calcium release, IP(3)-assisted CICR). To clarify its functional significance, the effects of IP(3)-assisted CICR on spike-frequency adaptation were examined in layer II/III neurons from rat visual cortex slices. IP(3)-assisted CICR was enabled with a high concentration of the mAchR agonist carbachol (10 microM). The magnitude of this CICR was the more augmented at higher firing frequencies. With 10 microM carbachol, spike-frequency adaptation was reduced for spike trains at 'low' firing frequencies (6-10 Hz), but was rather enhanced at 'high' firing rates (16-22 Hz): excitability was down-regulated at 'high' frequencies. With 1 microM carbachol, by contrast, IP(3)-assisted CICR failed to occur, and spike-frequency adaptation was always reduced at any spike frequencies. Intracellular injection of the IP(3) receptor blocker heparin prevented both the mAchR-mediated occurrence of IP(3)-assisted CICR and enhancement of spike-frequency adaptation with 10 microM carbachol. Both of these mAchR-mediated effects were reproduced by intracellular IP(3) injection, and were shown to be associated with each other by simultaneous recordings of membrane potential and intracellular calcium increase. We propose that IP(3)-assisted CICR offers a novel way to protect these cortical neurons from hyperexcitability and presumably from excitotoxic cell death.

Action Potentials↗
PubMed2002

A case of cold-dependent exercise-induced anaphylaxis.

Exercise-induced anaphylaxis (EIA) is a form of physical urticaria that is induced by exercise. A 16-year-old Japanese boy had a 4-year history of recurrent wealing and dyspnoea after physical exercise such as jogging, playing handball or riding a bicycle in winter. The episodes were not associated with ingestion of foods including wheat or soya bean. A provocation test, with 15 min of exercise and 2 min of cold stimulation immediately before or immediately after the exercise, elicited a weal that was localized to the test area. A challenge test with ingestion of boiled soya beans and exercise did not elicit a weal. Therefore, in this case, cold exposure, but not food ingestion, was essential for inducing EIA. Cold-dependent EIA is different from cold urticaria, food-dependent EIA, cholinergic urticaria and cold-induced cholinergic urticaria, and may be a distinct entity.

Adolescent↗
PubMed2002

Transcriptional regulation of serum amyloid A1 gene expression in human aortic smooth muscle cells involves CCAAT/enhancer binding proteins (C/EBP) and is distinct from HepG2 cells.

Regulation of acute-phase serum amyloid A (A-SAA) synthesis by proinflammatory cytokines and steroid hormones in human aortic smooth muscle cells (HASMCs) is distinct from that in HepG2 cells. To study the cis- and trans-activating promoter element involved in the SAA1 gene expression by HASMCs and HepG2 cells, we constructed plasmid vectors for luciferase reporter gene assay with varying lengths of SAA1 upstream regulatory region (up to 1431 bp), and examined their response to proinflammatory cytokines and/or steroid hormones. The corresponding vectors with the SAA4 upstream regulatory region served as controls. The presence of proposed transcriptional regulatory factors binding to these regions was confirmed immunohistochemically. The sequences of 1478 and 1836 bp of the SAA1 and SAA4 5'-flanking regions were determined, respectively. SAA1 promoter transcription in cultured HASMCs was upregulated not by proinflammatory cytokines, but rather by glucocorticoids. This differed from HepG2 cells, in which SAA1 promoter transcription was upregulated synergistically by proinflammatory cytokines and glucocorticoids. The promoter activity of a series of truncated SAA1 promoter constructs measured using the reporter gene assay showed that the 5'-region from -252 to -175, containing a consensus site for CCAAT/enhancer binding proteins alpha,beta (C/EBPalpha,beta), was essential for SAA1 induction in HASMCs. In HepG2 cells, the 5'-region from -119 to -79, containing a nuclear factor kappa-B (NFkappaB) consensus sequence, was essential for the induction. The functional significance of the C/EBP site as indicated by the immunohistochemical result was that in HASMCs anti-C/EBPbeta reactivity was shifted from the cytoplasm to the nuclei. We have, therefore, demonstrated that the region containing the C/EBPalpha,beta consensus binding site between the bases -252 and -175 is important for the glucocorticoid-induced SAA1 gene expression in HASMCs but not in HepG2 cells.

Base Sequence↗
PubMed2002

Suppression of airway hyperresponsiveness induced by ovalbumin sensitisation and RSV infection with Y-27632, a Rho kinase inhibitor.

BACKGROUND: Smooth muscle contraction is one of the hallmarks of asthma. A recently developed pyridine derivative, Y-27632, a selective Rho kinase inhibitor, has been reported to inhibit the smooth muscle contraction of human and animal trachea in ex vivo systems but its effect in animal models of airway hyperresponsiveness (AHR) has not been examined. The purpose of this study was to evaluate the effect of Y-27632 in a murine model of allergic and virally induced AHR. METHODS: Baseline lung resistance and methacholine induced AHR were measured in mice sensitised to ovalbumin (OVA) and also in mice infected with respiratory syncytial virus (RSV) following ovalbumin sensitisation (OVA/RSV). RESULTS: Time course and dose ranging experiments indicated that 30 mg/kg Y-27632 given by gavage 2 hours before methacholine challenge significantly reduced baseline lung resistance and prevented AHR in OVA sensitised mice. Y-27632 also suppressed AHR induced by the bronchospastic agent serotonin in OVA sensitised mice and prevented methacholine induced AHR in OVA/RSV mice. CONCLUSIONS: These results suggest that the signalling pathway mediated through Rho kinase may have an important role in bronchial smooth muscle tone in allergen induced and virus induced AHR and should be considered as a novel target for asthma treatment.

Airway Resistance↗
PubMed2002

Bactericidal activities of commonly used antiseptics against multidrug-resistant mycobacterium tuberculosis.

Seventeen clinical isolates of Mycobacterium tuberculosis were selected in order to study the bactericidal activities against drug-resistant M. tuberculosis. The effects of different antiseptics against multidrug-resistant M. tuberculosis (MDR-TB) were examined. Each of the test strains was cultured on the surface of an agar slant containing Löwenstein-Jensen medium. 0.05 ml of the bacillary suspension was poured into a test tube, and 0.45 ml of various antiseptics was added. After the bacilli had been exposed to the antiseptic solution with 2% human serum for various periods of incubation time, the antiseptic was inactivated by addition of 0.45 ml neutralizer, a mixture containing 10% Tween 80, 3% soybean lecithin and 0.5% sodium thiosulfate. As the results, povidone-iodine (PVP-I) at a concentration of 0.2% killed 99.9% or more of all strains tested within 30 s. All of the strains tested with PVP-I were killed almost completely within 60 s. There was no difference in bactericidal activities of PVP-I between standard strain H37Rv and MDR-TB. 99.9% or more of all strains tested were killed after exposure to 1.0% cresol for 60 s. In the case of cresol however, the exposure time of 30 s was not enough to get satisfactory effects. 2.0% glutaraldehyde needed 5 min to kill 99.99% or more of the bacilli tested, and 0.2% alkyldiaminoethylglycine hydrochloride required 60 min to do so. The results of bactericidal activities of common antiseptics against MDR-TB were similar to those against H37Rv. We conclude that the commercially available PVP-I product is a useful antiseptic against MDR-TB similar to other M. tuberculosis.

Anti-Infective Agents, Local↗
PubMed2002

Sperm phospholipase Czeta from humans and cynomolgus monkeys triggers Ca2+ oscillations, activation and development of mouse oocytes.

Fusion with a fertilizing spermatozoon induces the mammalian oocyte to undergo a remarkable series of oscillations in cytosolic Ca(2+), leading to oocyte activation and development of the embryo. The exact molecular mechanism for generating Ca(2+) oscillations has not been established. A sperm-specific zeta isoform of phospholipase C (PLCzeta) has been identified in mice. Mouse PLCzeta triggers Ca(2+) oscillations in mouse oocytes and exhibits properties synonymous with the 'sperm factor' that has been proposed to diffuse into the oocyte after gamete fusion. The present study isolated the PLCzeta homologue from human and cynomolgus monkey testes. Comparison with mouse and monkey PLCzeta protein sequences indicates a shorter X-Y linker region in human PLCzeta and predicts a distinctly different isoelectric point. Microinjection of complementary RNA for both human and cynomolgus monkey PLCzeta elicits Ca(2+) oscillations in mouse oocytes equivalent to those seen during fertilization in mice. Moreover, human PLCzeta elicits mouse egg activation and early embryonic development up to the blastocyst stage, and exhibits greater potency than PLCzeta from monkeys and mice. These results are consistent with the proposal that sperm PLCzeta is the molecular trigger for egg activation during fertilization and that the role and activity of PLCzeta is highly conserved across mammalian species.

Amino Acid Sequence↗
PubMed2002

Efficacy of common antiseptics against multidrug-resistant Mycobacterium tuberculosis.

OBJECTIVES: The incidence of infections caused by multidrug-resistant strains of Mycobacterium tuberculosis (MDR-TB) has been increasing. Antiseptics are frequently used to prevent mycobacterial infection. The aim of this study was to determine those antiseptics that are useful against MDR-TB. DESIGN: We evaluated bactericidal activity against clinical isolates of MDR-TB in vitro. METHOD: Thirteen strains of MDR-TB were tested against povidone-iodine (PVP-I), cresol, akyldiaminoethyl glycine hydrocloride (AEG), and glutaraldehyde. After bacilli were exposed to the antiseptic solution with 2% human serum, the disinfectant was inactivated by addition of neutraliser. RESULTS: PVP-1 at a final concentration of 0.2% killed all of the strains within 120 seconds, and PVP-I at 0.1% killed 99.9% or more bacilli within 60 seconds. Most strains were killed after exposure to 0.5% cresol at 300 seconds and to 1.0% cresol at 60 seconds; 3.0% cresol killed all bacilli within 120 seconds, while 0.1%, 0.2%, and 0.5% AEG all required 60 minutes to kill 99.9% or more of the bacilli; 2.0% glutaraldehyde required 10 minutes to kill all bacilli. CONCLUSION: The bactericidal activities of antiseptics for MDR-TB were similar to those for drug-sensitive M. tuberculosis strains. PVP-I would be a useful antiseptic against MDR-TB. The bactericidal activities of glutaraldehyde are effective against MDR-TB as an antiseptic for medical equipment.

Anti-Infective Agents, Local↗
PubMed2002

The role of plasma endothelin in the Fontan circulation.

BACKGROUND: Various vasoactive substances are released during cardiopulmonary bypass. They may deteriorate pulmonary circulation after the Fontan operation. Effects of plasma endothelin-1 (ET-1), a vasoconstricting peptide, on the Fontan circulation have not been investigated. METHODS: Eleven patients (aged 11.1+/-7.5 years) who underwent the modified Fontan operation (group F) and seven patients (aged 9.9+/-6.0 years) who underwent the biventricular repair (group C) were studied. Plasma samples were obtained for measuring ET-1 on the first postoperative day (Early I), on returning to floor care from the intensive care unit (Early II), and during postoperative cardiac catheterization (Late). RESULTS: Plasma concentrations of ET-1 increased in group F (Early I, 4.37+/-1.78 pg/ml; Early II, 4.07+/-1.90 pg/ml) as compared with the basal value of 1.0+/-0.5 pg/ml. The central venous pressure, which reflects the pulmonary circulatory state, soon after the Fontan operation correlated significantly with the increased ET-1 concentration (y=1.809 x+6.484; r=0.809; p=0.0026). Although the Late ET-1 concentrations in group F were significantly decreased, the central venous pressure and the ET-1 concentrations demonstrated a significant correlation (y=3.074 x +5.427; r=0.740; p=0.0227). CONCLUSIONS: The increased humoral vasoactive substances such as ET-1, which induces pulmonary vasoconstriction following the Fontan operation, may have important implications for the Fontan circulation.

Adolescent↗
PubMed2002

Removal of bromate ion from water using TiO2 and alumina-loaded TiO2 photocatalysts.

The effects of pH and the surface charge of photocatalyst on photocatalytic reduction of bromate ions in water were examined by using TiO2 and alumina-loaded TiO2 photocatalysts. The amount of adsorbed bromate ion on TiO2 and the reduction rate of bromate ion by the TiO2 photocatalyst increased with lowering pH. It was suggested that the bromate ion adsorbed predominantly on the positively charged surface sites of TiO2 at lower pH, which thus promotes the rate of reduction. The iso-electric point of the TiO2 photocatalyst was shifted to the higher pH region by loading alumina on the TiO2 surface, which resulted in the increase of the adsorbed amount of bromate on the photocatalyst and the reduction rate of bromate ion by the photocatalyst at neutral pH. It was concluded from these results that the photocatalytic reduction of bromate ion can be promoted by pH control of water or by controlling the surface charge of the photocatalyst by loading alumina without pH control of water.

Adsorption↗
PubMed2001

Beneficial effects of 3-dimensional visualization on hepatic vein reconstruction in living donor liver transplantation using right lobe graft.

BACKGROUND: Recently, virtual operation planning and navigation systems have been introduced in the field of neurosurgery and orthopedic surgery. We report here the beneficial effects of 3-dimensional (3D) visualization on hepatic venous reconstruction in living donor liver transplantation (LDLT) using right lobe graft. METHODS: 3D-image reconstruction of the liver was rendered with 3-mm slices of helical computed tomography (CT) data using zioM900 (Zio Software Inc., Tokyo, Japan). To understand the anatomy of the donor's vessels and design an operation plan, a picture of the vessels in and around the liver was reconstructed. RESULTS: The 3D image demonstrated two short hepatic veins next to the inferior right hepatic vein (IRHV) as well as a large IRHV. The 3D image showed a more precise diameter of the right hepatic vein (RHV) and the IRHV and a more accurate distance between the two hepatic veins than did images measured by 2-dimensional CT. This preoperative information allowed the donor surgeon to dissect the inferior vena cava (IVC) and hepatic veins with reduced blood loss because of reduced risk of injury to the blood vessels. The 3D image revealed that both the RHV and the IRHV branched off at the same angle from the cylindrical IVC. Preoperative planning based on this information secured smooth anastomosis. CONCLUSIONS: 3D visualization is useful for hepatic venous reconstruction of the recipient as well as for donor surgery in LDLT using right lobe graft.

Female↗
PubMed2001

Retinotopic hemodynamic activation of the human V5/MT area during optokinetic responses.

To detect retinotopic activation in the human V5/MT, we obtained fMRI signals during optokinetic responses (OKR). We used two types of patterns, consisting of random dots plotted in either the central or peripheral regions, to stimulate the central and peripheral visual fields, respectively. These patterns moved at a constant speed of 20 degrees/s rightward and leftward alternately. Subjects were required to track the patterns with their eyes. The two types of visual stimuli elicited different patterns of brain activation; the area with the most significant response to central visual field stimuli was located posteriorly to that responding to peripheral visual field stimuli.

Adult↗
PubMed2001

Effects of adrenomedullin on adrenocorticotropic hormone (ACTH) release in pituitary cell cultures and on ACTH and oxytocin responses to shaker stress in conscious rat.

Adrenomedullin (AM) is a potent vasodilator peptide, which is initially isolated from tissue of human pheochromocytoma. In addition to the effect on cardiovascular system, previous studies suggest that AM plays some roles as a neuropeptide in the brain. In the present study, we examined the effect of AM on in vitro adrenocorticotropic hormone (ACTH) secretion stimulated by corticotropin-releasing hormone (CRH), vasopressin (VP) or oxytocin (OT) in cultured rat corticotrophs and on the response of plasma ACTH, corticosterone (B) and OT to shaker stress in vivo. In contrast to the previous report, basal or CRH (10(-9) M)-stimulated ACTH secretion was not affected by coincubation with AM. Either of VP (10(-8) M) or OT (10(-8) M) significantly increased ACTH secretion in cultured rat anterior pituitary cells (156.7+/-24.9 in basal incubation vs. 267.8+/-15.0 in VP-stimulation, P<0.05, and 308.6+/-41.3 pg/ml in OT-stimulation, P<0.05). AM (10(-10) M) significantly inhibited OT-stimulated ACTH secretion. AM tended to inhibit VP-stimulated ACTH secretion, although the inhibitory effect was not statistically significant. Thus, it is likely that AM attenuates OT-stimulated ACTH secretion in corticotrophs. In vivo study, male Wistar rats were prepared with a guide cannula in the lateral ventricle and a catheter in femoral artery for blood sampling. AM (0.5, 1.0 microg in 5 microl) or normal saline (5 microl, control) was intracerebroventricularly (i.c.v.) injected in conscious rats. Shaker stress (110 cycles/min for 5 min) produced a significant increase of plasma ACTH (baseline: 106.4+/-48.6; vs. just after stress: 388.9+/-56.1 pg/ml, P<0.05) and B (baseline: 198.6+/-46.8 vs. 15 min after stress: 378.5+/-13.6 ng/ml, P<0.05) in the control group. Plasma OT tended to increase after stress, although the change was not significantly different (baseline: 29.8+/-6.5; just after stress: 65.6+/-18.2 pg/ml). I.c.v. injection of AM at 3 min before the stress did not significantly affect stress-induced changes of plasma ACTH, B and OT. These results suggest that AM has an inhibitory effect on OT-induced ACTH release in vitro and the inhibitory effect may be overwhelmed in ACTH and B response to shaker stress.

Adrenocorticotropic Hormone↗