Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 37 records · Page 2Linked to original sources

PubMed2003

Sasa-Satsuma higher-order nonlinear Schrödinger equation and its bilinearization and multisoliton solutions.

Higher-order and multicomponent generalizations of the nonlinear Schrödinger equation are important in various applications, e.g., in optics. One of these equations, the integrable Sasa-Satsuma equation, has particularly interesting soliton solutions. Unfortunately, the construction of multisoliton solutions to this equation presents difficulties due to its complicated bilinearization. We discuss briefly some previous attempts and then give the correct bilinearization based on the interpretation of the Sasa-Satsuma equation as a reduction of the three-component Kadomtsev-Petviashvili hierarchy. In the process, we also get bilinearizations and multisoliton formulas for a two-component generalization of the Sasa-Satsuma equation (the Yajima-Oikawa-Tasgal-Potasek model), and for a (2+1)-dimensional generalization.

Journal Article↗

PubMed2003

Immobilization of Candida krusei cells producing phytase in alginate gel beads: an application of the preparation of myo-inositol phosphates.

Cells of Candida krusei capable of producing phytase were immobilized in Ca-alginate gel beads and used for the preparation of myo-inositol phosphates. The immobilization yield was increased about 5-fold after the beads were treated for 96 h at pH 4.0, 4 degrees C. The increased yield was retained, even after 1 month, when the cells were kept at this temperature and pH. No shift in the pH optima of phytase of the immobilized cells was observed, compared with that of free cells. However, the optimum temperature for the enzyme of the immobilized cells was 55 degrees C, which was 15 degrees C higher than that of free cells. The degradation characteristics of the phytate in immobilized cells packed in a glass column (i.d. 1.2 cm, length 20 cm) were investigated. The variation in the composition of the products results from a change in the flow rate of phytate solution (5 mM). At a flow rate of 1.30 ml/min, a mixture of myo-inositol-2-monophosphate, myo-inositol-1,2,5-triphosphate and myo-inositol-1,2,5,6-tetrakisphosphate was produced, in which the latter two were physiologically active. Also, it was found by NMR analysis that the enzyme of this strain produced only one isomer of each of the inositol phosphates, with the exception of myo-inositol pentakisphosphate. Therefore, the pure isomers were easily isolated using ion-exchange chromatography.

6-Phytase↗

PubMed2003

Meningio-angiomatosis in a patient with focal epilepsy: value of PET in diagnoses and preoperative planning of surgery.

A 17-year-old boy with epileptic seizures due to meningio-angiomatosis without neurofibromatosis type 2 is presented. Low grade astrocytoma in the left temporal lobe was resected when he was 11 years old. A recurrence was suspected on following-up MRI and a positive PET scan with 11C-methionine PET 6 years later around the resected area. The language area was mapped using H2(15)O PET activation technique. The lesion was completely resected while preserving the verbal area assisted by three-dimensional imaging protocol of MR-registered PET. The patient was well and seizure-free for 8 years thereafter without antiepileptic drugs. Histologically, there was an increase of dilated arterioles and meningothelial cell-like spindle cells around them, which are characteristic pathological features of meningio-angiomatosis. It is most likely that angiomatous tissue developed perivascular meningiomatous components and formed the meningio-angiomatosis in our presented case. In addition, we presented our protocol of functional neuro-imaging which was useful in terms of the functional neurosurgery.

Adolescent↗

PubMed2003

Evaluation of two algorithms for counting forward saccades in a reading task.

We compared two algorithms, which are used to assess the number of forward saccades in a reading task from records of eye movements. In one algorithm saccades are detected analysing the velocity of eye movements. The third derivate of eye position in time (jerk) is used in the second algorithm for the detection of saccades. Both algorithms were applied on the same set of data, recorded using 24 subjects reading a German text, which was presented on two different displays. Our subjects read the text at a mean reading speed of 258.5 word/min. Both algorithms were found to produce a similar rate of artefacts in the number of detected saccades (2.5%), provided the threshold for detection (velocity or jerk) is set at an appropriate level and the same level of threshold is applied to all data. In both algorithms, the rate of artefacts increases with increasing distance of the threshold from its optimum. Inter-individual variation of the rate of artefacts increases more pronounced in the algorithm based on jerks. Eye blinks were identified as a major source of artefacts. A remedy is proposed, by means of which the rate of artefacts can be reduced.

Adult↗

PubMed2003

Expression of estrogen, progesterone and androgen receptors in the oviduct of developing, cycling and pre-implantation rats.

To determine expression and localization of receptors for estrogen (ER), progesterone (PR) and androgen (AR), detailed immunohistochemical evaluations were performed in the Sprague-Dawley rat oviduct during pre- and neonatal development, estrous cycle and pre-implantation period. In addition, real-time RT-PCR studies were conducted to evaluate changes in ERalpha, ERbeta, total PR (PR-A+B), PR-B and AR mRNA expressions. All receptors except for ERbeta were detected in epithelial, and stromal or mesenchymal cells of the fetal and neonatal oviduct, and increased with development. During the estrous cycle and early pregnancy, ERalpha and PR-A+B were expressed in epithelial, stromal and muscle cells throughout the oviduct region, and showed changes in expression predominantly in the isthmus. Only a few epithelial cells in the infundibulum (inf) and ampulla (AMP) showed ERbeta staining. AR was detected in stromal and muscle cells throughout the oviduct region, and in epithelial cells of the inf/AMP. Taken together, ERalpha, PR-A+B and AR were detected in the epithelium of the inf/AMP region, but all of these receptors were expressed in a distinct subset of epithelial cells which were negative for beta-tubulin IV, a ciliated epithelial cell marker. These results contribute to a better understanding of the respective roles of ERs, PRs and AR in the rat oviduct.

Animals↗

PubMed2002

Production of canthaxanthin by Haloferax alexandrinus under non-aseptic conditions and a simple, rapid method for its extraction.

The production of carotenoids from Haloferax alexandrinus strain TM(T) was investigated at various concentrations of NaCl (10-25%) in culture media under non-aseptic conditions. PCR and dot blot hybridization assays were employed to monitor the growth of Hfx. alexandrinus in the culture under aseptic and non-aseptic conditions. The amplified PCR products of 16S rDNA from Hfx. alexandrinus grown under aseptic conditions were used as specific probes, which bound with amplified PCR products of 16S rDNA dots from both aseptic and non-aseptic conditions (20-25% NaCl). The results indicated that contamination of the culture was precluded at high NaCl concentrations (20-25%). Therefore, it is not necessary to perform asepsis during the biotechnological processes of carotenoid production by Hfx. alexandrinus. A 1-l-scale cultivation of the cells in flask cultures under non-aseptic conditions produced 3.12+/-0.5 g dry weight, 6.34+/-2.5 mg total carotenoids and 2,156.67+/-0.1 microg canthaxanthin. Further experiments in a batch fermenter, under non-aseptic conditions, also demonstrated increases in the biomass concentration and carotenoid production. When grown in a standard growth medium at 25% NaCl, the cells of Hfx. alexandrinus lysed spontaneously in fresh water and hence carotenoids could be extracted directly from the cells without any mechanical disintegration. These results demonstrate the feasibility and simplicity of commercial production of carotenoids using Hfx. alexandrinus.

Base Sequence↗

PubMed2002

There is no valid evidence presented as to an impaired endothelial NO system in the stroke-prone spontaneously hypertensive rats.

Platelet reactivity in stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) were compared. In vivo platelet reactivity was tested by the He-Ne laser-induced thrombosis model. The number of laser pulses needed to reach thrombotic occlusion of the targeted vessel was used as an index of thrombogenicity. SHRSP rats needed significantly less number of irradiation to reach occlusion than WKY rats (SHRSP vs. WKY, 5.1+/-0.3 vs. 8.1+/-0.6), indicating enhanced thrombotic response in SHRSP rats. Further, acetylcholine administration significantly increased the number of laser pulses until occlusion in WKY but not in SHRSP rats. This suggests an impaired thrombotic reaction in acetylcholine-treated WKY but not in SHRSP rats. Platelet reactivity in vitro was measured in native blood by a shear-induced haemostasis test (haemostatometry). Indexes of this test (H1/H2), which inversely correlated with platelet reactivity, were significantly greater in SHRSP than in WKY rats (SHRSP vs. WKY, H1: 1815+/-192 vs. 763+/-75; H2: 7547+/-723 vs. 3536+/-264). This suggests reduced platelet reactivity in SHRSP compared with WKY rats. Thus, the present findings show increased thrombotic tendency in SHRSP rats in vivo despite reduced platelet reactivity in vitro. To explain this contradiction, we suggest that an increased in vivo thrombotic tendency may be due to impaired nitric oxide (NO) release from endothelial cells in SHRSP rats, and that a reduced platelet reactivity in vitro may be due to an adaptation of SHRSP rats to survive at extremely high blood pressure.

Acetylcholine↗

PubMed2002

Proton energy spectra in the nonmesonic weak decay of 12lambdaC and 28lambdaSi hypernuclei.

Numbers of protons per Gamma hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of Gamma hypernuclei by the (pi+,K+) reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the Gamma(n)/Gamma(p) ratios are close to 1 both for 12LambdaC and 28LambdaSi in contradiction to theoretical expectations based on meson exchange models.

Journal Article↗

PubMed2002

A case of paroxysmal kinesigenic dyskinesia with spastic paraparesis.

We report the first case of paroxysmal kinesigenic dyskinesia (PKD) with spastic paraparesis. A 17-year-old male began to show a dystonic posture in both his upper limbs when walking at age 12 years. Neurological examination revealed bilateral talipes cavus, spasticity in all extremities with general hyperreflexia and pathological reflexes. On starting to walk, he showed a dystonic posture in bilateral maniphalanx, wrists, elbows, and toes. Magnetic resonance imaging (MRI) revealed high T2-weighted signal intensity in bilateral pyramidal tract. Although the combination of pyramidal and the basal ganglia disorders is very rare, the present case suggests an inter-relation of the pyramidal and the basal ganglia systems.

Adolescent↗

PubMed2002

Changes in ontogenetic expression of estrogen receptor alpha and not of estrogen receptor beta in the female rat reproductive tract.

To evaluate ontogenetic expression and localization of estrogen receptor (ER) alpha and beta in fetal female rat reproductive tract, competitive RT-PCR and immunohistochemistry were performed. Expression levels for Müllerian ERalpha, ERbeta1 and ERbeta2 mRNAs were determined by competitive RT-PCR. ERalpha expression on gestational day (GD) 15 x 5 increased 4 x 4-fold by GD 21 x 5, whereas both ERbeta1 and ERbeta2 gene expression were maintained at lower constant levels compared with ERalpha during development. ER immunolocalization was evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. Nuclear ERalpha was localized predominantly in proximal Müllerian epithelium, and middle and caudal Müllerian mesenchyme on GDs 15 x 5-21 x 5. Staining intensity for ERalpha increased with development in all regions. However, ERbeta immunoreactivity was not detected in any region during prenatal life after separate staining with three different polyclonal anti-rat ERbeta antibodies. These findings provide fundamental information critical for clarifying the species-specific physiological roles of ER subtypes during fetal development and for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen and estrogen receptor agonists.

Animals↗

PubMed2002

[Thymic carcinoma; analysis of nine clinical studies].

Nine cases of thymic carcinoma (mean age 53.9 years old, 8 males and 1 female) were treated in our hospital from 1973 to 1998. The histological subtypes of thymic carcinoma were squamous cell in six, adenosquamous cell in one, Lymphoepithelioma-like carcinoma in one, mixed type of small cell and squamous cell in one. We applied Yamakawa clinical staging, 9 cases consisted of 2 stage II cases, 2 stage III cases, and 5 stage IV b cases. Adjuvant radiotheraphy was administered in one case, registering remarkable reduction of tumor size. All of the four cases which had been performed complete resection are alive without recurrence for 17 to 136 months after operation. The mean survival time was 47 months in stage III, and 18 months in stage IV b. By the review of the Japanese literature, most of the patient who revealed long-term survival fulfill the conditions as follow, squamous cell carcinoma in histologically, earlier stage than III at his operation, performed complete resection, performed postoperative radiotherapy. Our cases covering all these condition are alive without carcinoma for 136 months after operation.

Adult↗

PubMed2001

An inhibitor of inducible nitric oxide synthase decreases forearm blood flow in patients with congestive heart failure.

OBJECTIVES: The functional activation of inducible nitric oxide synthase (iNOS) was evaluated as a source of nitric oxide (NO) in the forearm of patients with heart failure. BACKGROUND: Although endogenous NO is normally produced by constitutive NO synthase (cNOS) in patients with congestive heart failure (CHF), expression of iNOS provides an additional source of NO. However, there are no in vivo studies showing functional activation of iNOS in humans. METHODS: A nonselective NOS inhibitor, N(G)-monomethyl-L-arginine (L-NMMA), and a selective inhibitor of iNOS, aminoguanidine, were administered intra-arterially in graded doses into the brachial arteries of 13 patients with CHF and 10 normal control subjects. Forearm blood flow (FBF) was measured simultaneously in the infused and noninfused arms by plethysmography. Arterial and venous plasma concentrations of nitrite/nitrate (NOx) were measured at baseline and at the highest dose of each drug. RESULTS: L-NMMA significantly reduced the FBF ratio between the infused and noninfused arms in both the control and patient groups (35 +/- 12% and 34 +/- 10%, respectively; both p < 0.001). Aminoguanidine at the same concentration significantly reduced the ratio in the patient group (15 +/- 9%, p < 0.01), with no change in the control group. The arterial NOx concentration was not affected by either drug; however, venous NOx concentrations were significantly decreased in both the control and patient groups by L-NMMA (18 +/- 5% and 18 +/- 17%, respectively; both p < 0.05) and in the patient group only by aminoguanidine (7 +/- 6%, p < 0.05). CONCLUSIONS: These findings suggest that NO production in the forearms of patients with CHF is induced partly by iNOS activation, whereas in normal subjects, it can be ascribed to cNOS activation.

Acetylcholine↗

PubMed2001

Ascorbate-induced high-affinity binding of copper to cytosolic proteins.

Copper chaperones are necessary for intracellular trafficking of copper to target proteins. This is probably because the milieu inside the cell has a large capacity for sequestering this metal. By fluorometry using a fluorescent Cu(II) chelator and by centrifugal ultrafiltration, we have studied copper binding of the whole cytosolic proteins from mouse brain and liver, and found that their binding capacity and affinity for copper were markedly increased by ascorbate. Brain cytosolic protein bound, with high affinity, 63 nmol of copper/mg, more than half of which was redox-inactive, as indicated by its inability to catalyze oxidation of ascorbate. Most of the bound copper was in the Cu(I) state, coordinating to thiol groups of protein. Cytosolic protein competed for copper more strongly than GSH when compared at their relative concentrations in tissues. The results taken together suggest that protein thiols of cytosol can strongly sequester copper.

Animals↗

PubMed2001

Full-genome nucleotide sequence of a hepatitis E virus strain that may be indigenous to Japan.

We identified hepatitis E virus (HEV) RNA in serum from a Japanese patient with acute hepatitis, who had never been abroad. The full-genome nucleotide sequence of the HEV isolate (JRA1) from this patient was composed of 7227 nucleotides excepting the poly(A) tail and had ORF1 coding for 1703 amino acids (aa), ORF2 coding for 660 aa, and ORF3 coding for 122 aa. This Japanese strain showed approximately 87% nucleotide similarity to human and swine strains reported from the United States, while it had only 73-76% similarity to Asian and Mexican strains. Here we report the characteristics of the HEV-JRA1 isolate, which might be the first example of an indigenous strain(s) of HEV in Japan.

Amino Acid Sequence↗

PubMed2001

The expression of vascular endothelial growth factor C and its receptors in non-small cell lung cancer.

Expression of vascular endothelial growth factor (VEGF)-C and that of its receptors were assessed in non-small cell lung cancer. Immunohistochemistry revealed positive VEGF-C expression in 38.7% (24/62) of the patients studied. A significant positive correlation was found between VEGF-C in cancer cells and VEGF receptor-3 (VEGFR-3) in vascular endothelial cells, but not between VEGF-C in cancer cells and VEGFR-2 in endothelial cells. In this cohort of lung cancer patients, VEGF-C expression was significantly associated with lymph node metastasis, lymphatic vessel invasion, and worse outcomes after the operation. Although the independent prognostic impact of VEGF-C and VEGFR-3 was not clear, VEGFR-2 expression in endothelial cells retained the independency as the prognostic indicator. In light of these findings, we conclude that VEGF-C plays an important role in lymphatic invasion/metastasis and tumour progression in non-small cell lung cancer.

Aged↗

PubMed2001

Expression of NeuroD and TrkB in developing and aged mouse olfactory epithelium.

To better understand the roles of NeuroD, a member of the basic helix-loop-helix transcription factor family, during the differentiation of olfactory receptor neurons, we studied the expression of NeuroD in developing and aging mouse olfactory epithelium (OE). During embryonic period, NeuroD expression is confined in the basal compartment of OE. During neonatal period, NeuroD expression is detected in the middle compartment and in the basal compartment of OE. In the adult, the number of NeuroD expressing cells in the basal compartment significantly decreased, while the NeuroD-positive cells in the middle compartment was maintained throughout lifetime. This dual phase expression pattern of NeuroD suggests multiple roles of NeuroD in the neurogenesis of ORNs.

Aging↗

PubMed2001

Immunohistochemical investigation of caspase-1 and effect of caspase-1 inhibitor in delayed neuronal death after transient cerebral ischemia.

The localization of caspase-1 protein, interleukin-1beta (IL-1beta)-converting enzyme, was immunohistochemically examined in the hippocampal CA-1 subfield by a transient occlusion of bilateral common carotid arteries in Mongolian gerbils. Immunoreactivities for caspase-1 were found in microglias, astrocytes, endothelial cells of capillaries and some non-pyramidal neurons. Immunopositive microglias increased in number from 3 days until 7 days from the transient ischemia, and astrocytes also increased in number from 3 days until 28 days. At the electron microscopic level, caspase-1 immunoreaction endproducts were associated with Golgi apparatus in glial cells, endothelial cells of blood vessels and non-pyramidal neurons. The delayed neuronal death of CA-1 pyramidal cells was significantly protected by the treatment of specific caspase-1 inhibitor (Ac-WEHD-CHO) or broad caspase family inhibitor (z-VAD-FMK). Cell death was protected in a dose dependent manner by the former by 43-57%, and by the latter by 66-91% when injected at 1 and 10 microg, respectively. On the other hand, the protective effect of specific caspase-3 inhibitor (Ac-DMQD-CHO) was less significant at higher dose (10 microg) by 33% (P<0.05), and not detectable at lower dose (1 microg) by 13% (P=0.27). Furthermore, a significant decrease of microglias and astrocytes was found in the CA-1 as well as the reduction of IL-1beta and caspase-1 immunoreactivities by the treatment of Ac-WEHD-CHO. Extravasation of serum albumin was also extremely reduced by this treatment. These findings suggest that the inhibition of caspase-1 activity ameliorates the ischemic injury by inhibiting the activity of IL-1beta.

Amino Acid Chloromethyl Ketones↗

PubMed2001

Preventive effect of ebselen on acute gastric mucosal lesion development in rats treated with compound 48/80.

The preventive effect of ebselen, a seleno-organic compound, which is known to possess glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties, on the development of acute gastric mucosal lesions was examined in rats with a single injection of compound 48/80 (0.75 mg/kg, i.p.), a mast cell degranulator. Pre-administration of ebselen (p.o.) at a dose of 50 or 100 mg/kg, but not 10 mg/kg, prevented gastric mucosal lesion development at 3 h, but not gastric mucosal lesion formation at 0.5 h, after compound 48/80 injection, although any dose of pre-administered ebselen did not affect decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 0.5 and 3 h after compound 48/80 injection. A decrease in Se-glutathione peroxidase activity and increases in the activities of myeloperoxidase, an index of tissue neutrophil infiltration, and xanthine oxidase and the concentration of thiobarbituric acid reactive substances, an index of lipid peroxidation, were found in gastric mucosal tissues at 0.5 h after compound 48/80 injection and these changes were further enhanced at 3 h. Pre-administration of ebselen (p.o.) at a dose of 50 or 100 mg/kg, but not 10 mg/kg, attenuated all these changes found at 3 h after compound 48/80 injection. These preventive effects of ebselen occurred in a dose-dependent manner. The present results indicate that pre-administered ebselen prevents the development of compound 48/80-induced acute gastric mucosal lesions in rats, and suggest that this preventive effect of ebselen could be due to its glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties.

Animals↗