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Biomedical subjects

K Ono

Publications and source records attributed to K Ono.

At least 55 records · Page 3Linked to original sources
PubMed2003

Ta 5d band symmetry of 1T-TaS1.2Se0.8 in the commensurate charge-density-wave phase.

We present a detailed angle-resolved photoemission study on the layered transition-metal dichalcogenide 1T-TaS1.2Se0.8 in the commensurate charge-density-wave (CDW) phase. A drastic reduction in the spectral weight along the high symmetry line GammaM, particularly around the point M, is observed when s-polarized light was used. This implies that the initial state must be symmetric with respect to a mirror plane perpendicular to the line GammaK, which is consistent with conventional band calculations in the absence of the CDW. We conclude that there is only a limited amount of modification of the electronic structure of 1T-TaS1.2Se0.8 in the commensurate CDW phase due to the CDW-related potential.

Journal Article↗
PubMed2003

Hypermethylation of retrotransposons in the liverwort Marchantia paleacea var. diptera.

Three DNA fragments encoding part of a reverse transcriptase similar to that of Ty1- copia retrotransposons were isolated from suspension-cultured cells of the liverwort Marchantia paleacea var. diptera. Digestion of total DNA with methylation-sensitive and -insensitive isoschizomers revealed that, like those of the subtelomeric region, CpG sequences in retrotransposon genes were hypermethylated. The methylation status and expression of these retrotransposons was less affected by 5-azadeoxycytidine treatment compared to the subtelomeric region, which was considerably demethylated.

Amino Acid Sequence↗
PubMed2003

Easy and accurate targeting of deep-seated hepatic tumors under laparoscopy with a forward-viewing convex-array transducer.

BACKGROUND: It is technically difficult to puncture deep-seated hepatic tumors by conventional laparoscopic ultrasonography with a linear-array probe. We have developed a laparoscopic ultrasonography system with a convex-array probe. METHODS: The laparoscopic system used had a fixed forward-viewing convex-array transducer, and a guide groove for puncture was added to the back of the unit. These characteristics enabled us to continuously monitor the position of the needle tip on the ultrasonographic image immediately after puncturing on the liver surface. We attempted tumor puncture in 11 patients with hepatocellular carcinoma under a new probe guidance. RESULTS: The mean puncturing distance up to the tumors was 38.7 mm. All punctures were successful on the first pass and the tumors were treated with radiofrequency ablation. CONCLUSION: Using this new equipment, puncturing hepatic tumors for treatment is relatively easy, irrespective of the position of the tumor.

Adult↗
PubMed2003

Differential response to low temperature of two Delta6 fatty acid desaturases from Mucor circinelloides.

A recently identified Delta6 fatty acid desaturase in Mucor rouxii shows a low sequence homology (approximately 24% at the amino acid level) to that isolated from Mortierella alpina, but is phylogenetically closer to a plant enzyme, suggesting the occurrence of Delta6 desaturase isozymes in Mucorales molds. In the present study, two types of Delta6 desaturases, mcD6-1 ( Mo. alpina type) and mcD6-2 ( M. rouxii type), were cloned from Mucor circinelloides. When the cloned genes were expressed in the yeast Saccharomyces cerevisiae in the presence of a linoleic acid substrate (C18:2Delta9, 12), a newly generated gamma-linolenic acid (C18:3Delta6, 9, 12) was detected in the cells, which confirmed the suspected enzymatic function of the recombinant protein. This is the first report of Delta6 desaturase isozymes present in one organism. Northern analysis demonstrated that the amount of mcD6-2 mRNA was less than half of that of mcD6-1 mRNA in cells grown at 28 degrees C. However, upon cultivation of the cells at 15 degrees C for 0.5-1 h, mcD6-2 mRNA rapidly increased by up to 1.5-fold and then gradually decreased. By contrast, mcD6-1 transcripts levels did not fluctuate significantly for 1 h after the temperature shift, but declined by 75% over the next 2 h. The gamma-linolenic acid content in total fatty acid from M. circinelloides decreased at 28 degrees C, but was maintained at approximately 30% at 15 degrees C. These data suggest that Delta6 desaturase isozymes play physiologically distinct roles in the maintenance of cellular lipids and adaptation to low temperature.

Amino Acid Sequence↗
PubMed2003

cDNA cloning and functional expression of alpha-glucosidase from Mortierella alliacea.

We recently purified an alpha-glucosidase comprising 61-kDa and 31-kDa subunits from the fungus Mortierella alliacea and characterized its soluble starch-hydrolyzing activity. Here, the cDNA coding for this enzyme was cloned, revealing that it encodes a single polypeptide of 1,053 amino acids, with a calculated molecular mass of 117 kDa. Comparison between the deduced amino acid sequence and the partial sequences of the purified enzyme suggested that an immature protein can be converted into the two subunits of mature enzyme by post-translational processing at least three cleavage sites. Heterologous expression of recombinant alpha-glucosidase in yeast gave rise to a significant increase in hydrolytic activity toward maltose and soluble starch, in both intracellular and extracellular fractions. Immunoblot analysis using antiserum against the alpha-glucosidase revealed that the active enzyme expressed in yeast is also composed of two subunits. The yeast expression system provides a model suitable for investigating the polypeptide-processing event and structure-function relationship of the alpha-glucosidase with unique substrate specificity.

Amino Acid Sequence↗
PubMed2003

Two types of plastid ftsZ genes in the liverwort Marchantia polymorpha.

Two types of ftsZ genes (MpftsZ1 and MpftsZ2) were isolated from the liverwort Marchantia polymorpha by degenerate reverse transcription PCR. The MpFtsZ1 and MpFtsZ2 proteins are predicted to localize in chloroplasts. Genomic Southern analysis suggested that each ftsZ gene is a single-copy nuclear gene. Northern analysis confirmed that both genes are active. A phylogenetic tree constructed with the deduced MpFtsZ amino acid sequences suggests that MpFtsZ1 and MpFtsZ2 can be classified into the plant chloroplastic FtsZ1 and FtsZ2 families, respectively. This result suggests that two ftsZ families exist universally in land plants. The determination of the intron structures of both MpftsZ genes supported this hypothesis. The transformation of a sense MpftsZ2 overexpression construct into M. polymorpha produced a large chloroplast phenotype in a transgenic plant. The mean number of chloroplasts was 38.2 (standard deviation, 21.4; n = 200) in epidermal cells of wild-type plants, whereas the mean number of chloroplasts was 7.4 (standard deviation, 4.4; n = 200) in the transgenic plant. Southern analysis showed that the cauliflower mosaic virus 35S promoter- MpftsZ2 construct was inserted in at least three positions. Northern analysis suggested that the high accumulation of MpftsZ2 mRNA blocked plastid division. Determination of the chlorophyll content and the chlorophyll fluorescence parameters suggested that the macrochloroplasts function like chloroplasts in wild-type plants under normal light conditions. However, the transgenic plant grew more slowly than did wild-type plants.

Amino Acid Sequence↗
PubMed2003

Strength of bond to bone and cytotoxicity of sintered bodies of hydroxyapatite/zirconia composite particles.

Regarding sintered bodies of hydroxyapatite (HAP)/zirconia (PSZ) composite particles prepared by covering the surface of HAP particles with PSZ particles, their strength of the bond to bone after implanting them into an organism and their cytotoxicity were evaluated. Cytotoxicity tests were conducted by the colony formation method. Cytotoxicity was not observed in the sintered bodies of HAP/PSZ composite particles, or in sintered monolithic HAP body and sintered monolithic PSZ body. The strength of bond between a sintered body and a bone was evaluated by measuring the shear strength at the interface between them after a fixed period following implantation of a sintered body into a rabbit femur. In all cases of the sintered monolithic HAP body, and the sintered bodies of HAP/PSZ composite particles and monolithic PSZ body, when the implantation period increased, the shear strength of the sintered body/bone interface tended to increase. In particular, this tendency was very high in the case of sintered bodies of HAP/PSZ with weight ratios of 1/1.0 and 1/1.5, the shear strength for each reaching 20 MPa 12 months after implantation.

Journal Article↗
PubMed2003

Activation of muscarinic receptors in rat subfornical organ neurones.

Cholinergic muscarinic inputs to subfornical organ (SFO) neurones in rats were studied using histochemical, molecular-biological and electrophysiological techniques. Neurones in the medial septum and the diagonal band (MS-DBB) were retrogradely labelled by a tracer wheat germ agglutinin-conjugated horseradish peroxidase-colloidal gold complex injected into the SFO. Some in the MS-DBB were double-labelled by choline acetyltransferase (ChAT) antibody. Many ChAT-immunoreactive fibres were observed in the SFO. M3 muscarinic receptor subtype-like immunoreactivity, detected using a polyclonal antiserum, was observed in the SFO. In slice preparations, muscarine induced inward currents in a dose-related manner. The inward currents were suppressed by the relatively M3 muscarinic receptor selective antagonist 4-diphenylacetoxy-N-methylpiredine methiodide. In the whole-cell current mode, muscarine depolarized the membrane with increased frequency of action potentials. Reverse transcriptase-polymerase chain reaction showed the presence of M2-M5 receptor mRNA in the SFO tissues. These results suggest that the SFO receives cholinergic muscarinic synaptic inputs from the MS-DBB. Acetylcholine postsynaptically activates and depolarizes neurones in the SFO partly through specific muscarinic receptors, including M3 receptor subtypes.

Acetylcholine↗
PubMed2003

Radiation doses to neonates during X ray computed tomography examinations.

As the survival rate of newborns has increased, the number of X ray computed tomography (CT) examinations performed on neonates has been increasing. The exposure doses from CT examinations are known to be higher than those from conventional radiography. Although radiation sensitivity of neonates is higher than that of adults, there are few reports on dose estimates of neonates in CT examinations. Four cylindrical phantoms and one neonatal phantom have been developed to estimate doses to neonates during CT examinations. Using these phantoms and glass dosemeters, absorbed doses were measured. Estimated exposure doses to neonates were higher than those to adults, and our results suggest a need to optimise carefully CT examinations in newborns.

Birth Weight↗
PubMed2003

Neonatal doses from X ray examinations by birth weight in a neonatal intensive care unit.

The aim of this study was to investigate the frequency and type of X ray examinations performed on neonates classified according to their birth weight in a neonatal intensive care unit (NICU). In this study, the radiology records of 2408 neonates who were admitted to the NICU of Oita Prefectural Hospital between January 1994 and September 1999 were investigated. This study revealed that the neonates with earlier gestational ages and lower birth weights required longer NICU stays and more frequent X ray examinations made using a mobile X ray unit. The average number of X ray examinations performed on neonates of less than 750 g birth weight was 26 films per neonate. In regard to computed tomography and fluoroscopy, no significant relationship was found between the birth weight and number of X rays. This study revealed that the entrance-surface dose per neonate was dependent upon the birth weight, while the maximum dose was not dependent upon the birth weight. The average neonatal dose in the NICU was predominantly from computed tomography and fluoroscopy. The individual dose varied widely among neonates.

Abdomen↗
PubMed2002

Current rectification by Pauli exclusion in a weakly coupled double quantum dot system.

We observe spin blockade due to Pauli exclusion in the tunneling characteristics of a coupled quantum dot system when two same-spin electrons occupy the lowest energy state in each dot. Spin blockade only occurs in one bias direction when there is asymmetry in the electron population of the two dots, leading to current rectification. We induce the collapse of the spin blockade by applying a magnetic field to open up a new spin-triplet current-carrying channel.

Journal Article↗
PubMed2002

Periodate-treated, non-anticoagulant heparin-carrying polystyrene (NAC-HCPS) affects angiogenesis and inhibits subcutaneous induced tumour growth and metastasis to the lung.

Periodate-treated, non-anticoagulant heparin-carrying polystyrene consists of about ten periodate-oxidized, alkaline-degraded low molecular weight-heparin chains linked to a polystyrene core and has a markedly lower anti-coagulant activity than heparin. In this study, we evaluated the effect of non-anticoagulant heparin-carrying polystyrene on tumour growth and metastasis. Non-anticoagulant heparin-carrying polystyrene has a higher activity to inhibit vascular endothelial growth factor-165-, fibroblast growth factor-2- or hepatocyte growth factor-induced human microvascular endothelial cell growth than heparin, ten periodate-oxidized-heparin and ten periodate-oxidized-low molecular weight-heparin, which is probably due to the heparin-clustering effect of non-anticoagulant heparin-carrying polystyrene. Non-anticoagulant heparin-carrying polystyrene inhibited human microvascular endothelial cell, B16 melanoma and Lewis lung cancer cell adhesion to Matrigel-coated plates. Non-anticoagulant heparin-carrying polystyrene also showed strong inhibitory activities in the tubular formation of endothelial cells on Matrigel and B16-melanoma and Lewis lung cancer cell invasion in a Matrigel-coated chamber assay. In vivo studies showed that growth of subcutaneous induced tumours and lung metastasis of B16-melanoma and Lewis lung cancer cells were more effectively inhibited by non-anticoagulant heparin-carrying polystyrene than ten periodate-oxidized-heparin and ten periodate-oxidized-low molecular weight-heparin. Furthermore, non-anticoagulant heparin-carrying polystyrene markedly reduced the number of CD34-positive vessels in subcutaneous Lewis lung cancer tumours, indicating a strong inhibition of angiogenesis. These results suggest that non-anticoagulant heparin-carrying polystyrene has an inhibitory activity on angiogenesis and tumour invasion and may be very useful in cancer therapy.

Angiogenesis Inhibitors↗
PubMed2002

Derangement of autonomic nerve control in rat with right ventricular failure.

The effects of right ventricular hypertrophy and eventual right ventricular failure on autonomic nerve regulation of heart rate variability were investigated using rats with monocrotaline (MCT)-induced pulmonary hypertension. ECG signals were obtained from a radio transmitter placed into the subcutaneous pouch in the back of the male MCT-treated and control rats for 30 min every 6 h at a sample rate of 5 kHz with or without injection of atropine (2 mg/kg I.P.) or propranolol (4 mg/kg I.P.), in a room equipped with a climate controller. Heart rate (HR) and HR variability (HRV) were analyzed in each group by power spectrograms obtained by the fast-Fourier transform algorithm. The RR interval, total power (TP), low-frequency (LF) power (0.04-0.73 Hz), high-frequency (HF) power (0.73-2 Hz) and LF/HF (L/H) ratio were measured. HR was significantly increased in the MCT-treated rats (P<0.001), which also presented lower HRV than that of the control Wistar rats; TP (P<0.05) and HF (P<0.05) power, but not the L/H ratio, were significantly lower than that of the control rats. Responses of these parameters to a muscarinic antagonist (atropine: 2 mg/kg) and a beta-adrenergic antagonist (propranolol: 4 mg/kg), however, remained intact in the MCT-treated rats. Only the parasympathetic component of autonomic nervous controls of HRV was deranged in rats with MCT-induced right ventricular failure.

Journal Article↗
PubMed2002

Radiobiological characteristics of solid tumours depending on the p53 status of the tumour cells, with emphasis on the response of intratumour quiescent cells.

Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mTP53) or with a neo vector as a control (SAS/neo) were inoculated subcutaneously (s.c.) into both hind legs of Balb/cA nude mice. Mice bearing tumours received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all proliferating (P) cells in the tumours. The mice then received gamma-ray irradiation. Another group of mice received a series of test doses of gamma-rays while alive or after tumour clamping to obtain hypoxic fractions (HFs) in the tumours. Right after irradiation, the tumour cells were isolated and incubated with a cytokinesis blocker. The micronucleus (MN) frequency in the cells without BrdU labelling (=quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, 6 h after irradiation, tumour cell suspensions obtained in the same manner were used for determining the frequency of apoptosis in the Q cells. The MN frequency and apoptosis frequency in total (P+Q) tumour cells were determined from the tumours that were not pretreated with BrdU. In total cell populations, SAS/mTP53 cells were more radioresistant than SAS/neo cells in clonogenic survival. Q tumour cells exhibited a significantly lower apoptosis and MN frequency, probably due to their much larger HF, than total cells. In both total and Q cell fractions, SAS/mTP53 cells were less susceptible to apoptosis and more susceptible to micronucleation than SAS/neo cells. Obviously, TP53 status had the potential to influence the radiosensitivity of not only the total cells, but also the Q cells. However, irrespective of the TP53 status, significant differences in radiosensitivity between total and Q tumour cells were consistently observed. From the viewpoint of tumour control as a whole, including intratumour Q tumour cell control, a treatment modality for enhancing the Q cell response has to be considered.

Animals↗
PubMed2002

Molecular cloning and characterization of a new Japanese cedar pollen allergen homologous to plant isoflavone reductase family.

BACKGROUND: Japanese cedar (Cryptomeria japonica) pollen is a major cause of seasonal pollinosis, and more than 10% of Japanese people suffer from this allergic disorder. However, only two major pollen allergens, Cry j 1 and Cry j 2, have been identified and exclusively characterized. OBJECTIVE: The aim of this study was to explore and identify important Japanese cedar pollen allergens other than Cry j 1 or Cry j 2. METHODS: C. japonica cDNA library was immunoscreened by rabbit antiserum raised against a partially purified cedar pollen allergen fraction. An isolated cDNA clone was inserted into a glutathione S-transferase (GST)-tagged Escherichia coli expression vector to obtain recombinant GST fusion protein. Non-fusion recombinant protein was purified by glutathione Sepharose affinity chromatography in conjunction with factor Xa cleavage of the GST moiety. IgE-binding ability of the recombinant protein was then evaluated by western blot analysis and enzyme-linked immunosorbent assay (ELISA). RESULTS: The cDNA encodes 306 amino acids with significant sequence similarity to those of plant isoflavone reductase-like proteins, which include a recently identified birch pollen allergen Bet v 5. Western blot analysis demonstrated that recombinant protein was recognized by cedar pollinosis patient IgE. In contrast to Bet v 5 being reported as a minor allergen, the recombinant protein exhibited 76% IgE binding frequency (19/25) against pollinosis patients. CONCLUSION: Here we identified the third member of Japanese cedar pollen allergen homologous to isoflavone reductase. Its high IgE-binding frequency implicates that the isoflavone reductase homologue might be an additional major pollen allergen in C. japonica.

Allergens↗
PubMed2002

Ultrasound biomicroscopic study of sclerotomy sites after implantation of sustained release drug devices.

BACKGROUND/AIMS: To evaluate the potential of ultrasound biomicroscopy (UBM) as a tool to study the precise location and changes of sclerotomy sites of the eye with an intraocular drug delivery device. METHODS: Eight eyes of six patients (13 sites) who received ganciclovir implants were examined by UBM. Examinations were performed 1-26 months (mean 12.8 months) postoperatively. Serial transverse and radial sections of the anterior ciliary body around the sclerotomy sites were obtained. RESULTS: The ganciclovir implant contour was successfully viewed using an UBM with high reflectivity. Three implants were deviated anteriorly and they were very close to the ciliary body and the lens (anterior deviation), while four implants were deviated posteriorly and away from the lens (posterior deviation). The other six implants were located at the appropriate position as intended. A solitary homogeneous mass with a medium reflectivity around the suture tab was observed at 12 out of 13 sites in seven eyes. Thick membranes extending from sclerotomy sites to the ora serrata were found at two sites in two eyes. CONCLUSION: UBM is helpful in detecting abnormal manifestations around ganciclovir implants and is a valuable tool to assess the changes of the sclerotomy sites of the sustained released intraocular devices.

Antiviral Agents↗