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Biomedical subjects

Y Oda

Publications and source records attributed to Y Oda.

At least 235 records · Page 13Linked to original sources
PubMed1998

Simultaneous determination of nicotinic acid and its metabolites in rat urine by micellar electrokinetic chromatography with photodiode array detection.

Nicotinic acid, nicotinamide and their possible metabolites were successfully separated within 17 min by micellar electrokinetic chromatography using 50 mM borate buffer (pH 9.0) containing 150 mM sodium dodecyl sulfate as the running buffer. Calibration curves for all compounds showed good linearity in a range of 5 microg/ml and 250 microg/ml with good correlation. The present method did not require any clean-up procedures and made it possible to determine all metabolites without interference on a photodiode array detector. Urine samples collected from Wistar male rats were analyzed after high-dose oral or intravenous administration of nicotinic acid or nicotinamide. Metabolic pathways of nicotinic acid in male Wistar rats are also discussed.

Animals↗
PubMed1998

In situ mRNA hybridization study of the distribution of choline acetyltransferase in the human brain.

We examined the distribution of choline acetyltransferase (ChAT) mRNA in the brain of six autopsied individuals by in situ hybridization with 35S-labeled human ChAT riboprobes. Neurons containing hybridization signal for ChAT mRNA were observed in the nucleus of the diagonal band of Broca, the basal nucleus of Meynert, the caudate nucleus, the putamen, the pedunculopontine tegmental nucleus, the laterodorsal tegmental nucleus, the parabigeminal nucleus, the oculomotor nucleus and the trochlear nucleus. These findings were in good agreement with previous ChAT-immunohistochemical data. In contrast, labeled neurons were not observed in the medial septal and medial habenular nuclei, in which previously ChAT-immunoreactive neurons have been identified in many mammalian species, including the human. An unexpected result of the present study was the demonstration of neurons with ChAT mRNA signal in restricted areas of the human cerebral cortex.

Adult↗
PubMed1998

The calcium sensing receptor and its alternatively spliced form in keratinocyte differentiation.

We have recently reported the presence of the calcium sensing receptor (CaR) in keratinocytes and suggested that it signaled calcium-induced differentiation of these cells. cDNA clones encoding the full-length CaR were isolated from human keratinocytes. In addition, an alternatively spliced form that lacks exon 5, encoding a portion of the extracellular domain, also was found. The in frame deletion of 231 nucleotides of exon 5 resulted in the loss of function of the CaR as measured by calcium-stimulated production of inositol phosphates when transfected into HEK293 cells or keratinocytes. This variant produced a smaller CaR protein with an altered glycosylation pattern compared with the full-length CaR. Coexpression of the spliced variant with the full-length CaR reduced the function of the full-length CaR. The full-length CaR was expressed in undifferentiated keratinocytes consistent with their greater response to elevated extracellular calcium in terms of increased intracellular free calcium and production of inositol phosphates. The full-length CaR decreased as the keratinocytes differentiated with an increase in the ratio of the spliced variant to the full-length form. The relative proportions of these two forms of CaR may regulate the calcium responsiveness of keratinocytes during their differentiation.

Alternative Splicing↗
PubMed1998

Inhibitory long-term potentiation underlies auditory conditioning of goldfish escape behaviour.

Long-term potentiation (LTP), the increase in synaptic strength evoked by high-frequency stimulation, is often considered to be a cellular model for learning and memory. The validity of this model depends on the assumptions that physiological stimuli can induce LTP in vivo and that the resulting synaptic modifications correlate with behavioural changes. However, modifiable synapses are generally embedded deep in complex circuits. In contrast, the goldfish Mauthner (M)-cell and its afferent synapses are easily accessible for electrophysiological studies, and firing of this neuron is sufficient to trigger fast escape behaviour in response to sudden stimuli. We have previously shown that tetanic stimulation can induce LTP of the feedforward inhibitory synapses that control the excitability of the M-cell. Here we report that natural sensory stimulation can induce potentiation of this inhibitory connection that resembles the LTP induced by afferent tetanization. Furthermore, comparable acoustic stimulation produced a parallel decrease in the probability of the sound-evoked escape reflex. Thus we demonstrate for the first time, to our knowledge, a behavioural role for the long-term synaptic strengthening of inhibitory synapses.

Acoustic Stimulation↗
PubMed1998

Direct transfer of bovine embryos frozen-thawed in the presence of propylene glycol or ethylene glycol under on-farm conditions in an integrated embryo transfer program.

An integrated bovine embryo transfer program was conducted in collaboration with 11 Japanese prefectural livestock experiment stations. The program was conducted to evaluate the practicability of the direct transfer method for bovine embryos frozen-thawed in the presence of propylene glycol (PG) or ethylene glycol (EG) under on-farm conditions. Embryos at the compacted morula to expanded blastocyst stages were collected from superovulated donors on Day 7 or 8 after estrus and equilibrated in 1.6 M PG or 1.8 M EG in Dulbecco's phosphate-buffered saline (DPBS) supplemented with 20% heat-inactivated calf serum. Embryos were then loaded individually into a 0.25-ml straw and placed directly into a cooling chamber of a programmable freezer precooled to -7 degrees C. After 2 min, the straw was seeded, maintained at -7 degrees C for 8 min more, and then cooled to -30 degrees C either at 0.3 degree C/min or 0.5 degree C/min before being plunged into liquid nitrogen. Embryos at the same stages were also frozen in the presence of 1.4 M glycerol (GLY) by a conventional method, which served as a control. The frozen embryos were thawed by allowing the straws to stand in air for 5 to 10 sec and then immersing them in a 30 degrees C water bath. Embryos frozen-thawed in the presence of PG or EG were nonsurgically transferred into the uterine horn without diluting the cryoprotectant. Embryos frozen-thawed in the presence of GLY were nonsurgically transferred after removing GLY either by the stepwise method (GLY-I) or by in situ dilution with 0.3 M sucrose solution (GLY-II). A total of 1,273 (PG: 400, EG: 418, GLY-I: 177, GLY-II; 278) frozen-thawed embryos was transferred into recipients, yielding 545 pregnancies (overall: 42.8%, PG: 36.0%, EG; 44.7%, GLY-I; 48.6%, GLY-II; 46.0%). The pregnancy rate with PG was significantly lower than that with EG or GLY-II (P < 0.05). The pregnancy rate was affected by the type of cryoprotectant, the region where the embryo transfer program was carried out, the developmental stage of the embryos, the parity of the recipients, and corpus luteum (CL) quality of the recipients. There were no differences in rates of abortion and stillbirth among the 3 cryoprotectants. The present study demonstrates that EG can be effectively used as a cryoprotectant for freezing and direct transfer of bovine embryos, and that the direct transfer method is applicable under on-farm conditions.

Animals↗
PubMed1998

On telomere shortening in soft-tissue tumors.

PURPOSE: Specific simple DNA repeats occur at the telomeric ends of mammalian chromosomes. Loss of (G + C)-rich repeats can result in genetic instability, associated with tumorigenesis. So far, data on telomere shortening have not been available for different types of soft-tissue tumors. METHODS: Using tumor material and the blood of the corresponding patient, high-molecular-mass DNA was prepared by digestion with proteinase K and extraction with phenol/chloroform. A 10-microg sample of DNA was digested with the restriction enzyme HinfI. DNA fragments were separated in a 0.7% agarose gel, and in-gel hybridization was performed with the telomere-specific repeat probe (TTAGGG)3. RESULTS: Shortening of the telomere repeat was observed in 14/30 soft-tissue tumors; 5 tumors showed elongated telomere repeats, whereas the telomeres appeared unchanged in 11 tumors. Decreased telomere repeat length correlated with advanced age, DNA ploidy, and a higher proliferation index. There was no association between telomere repeat length and tumor grade. Interestingly, in contrast to other entities, all malignant schwannomas and leiomyosarcomas showed significantly reduced telomere lengths. An explanation for the telomere heterogeneity in liposarcomas may include differential telomerase reactivation in well and poorly differentiated tumors. CONCLUSIONS: Telomere shortening is frequent but not a uniform phenomenon in different types of soft-tissue tumor. Studies on telomerase activity should be performed in the same cohort of sarcomas.

Adult↗
PubMed1998

p53 and ras mutations in Ewing's sarcoma.

The role of tumor suppressor genes and oncogenes in the development of Ewing's sarcoma has not yet been fully clarified. In this study, we analyzed the frequency of p53 tumor suppressor gene mutation in exons 4-8 by PCR-SSCP and direct sequencing, and the expression of p53-protein in Ewing's sarcoma (ES) by using immunohistochemistry. The overexpression of MDM2, which acts as a functional inactivator of p53, was studied by immunohistochemistry. In addition, a screening for point mutations in the hot spot regions codon 12 and 13 of exon 1 and codon 61 of exon 2 of ras-genes (H-ras, N-ras, K-ras) was performed. In one case, a p53 gene mutation could be confirmed in codon 238 of exon 7 (1/24). Overexpression of MDM2 was found in five cases; in ras-genes, no mutations were detected. Compared with other highly malignant mesenchymal pediatric tumors such as osteosarcomas, mutations of p53 and ras in Ewing's sarcomas are an extraordinarily rare event. However, their frequency is comparable to that of PNET, suggesting that the low incidence of these mutations in ES and PNET could be group-specific for tumors of neuroectodermal genesis.

Adolescent↗
PubMed1998

The cholinergic locus: ChAT and VAChT genes.

The gene encoding the vesicular acetylcholine transporter has been localized within the first intron of the gene encoding choline acetyltransferase and is in the same transcriptional orientation. These two genes, whose products are required for the expression of the cholinergic phenotype, could therefore be coregulated. The promoters of both genes have been identified. The mechanisms that account for the regulation of the expression of both genes are now being investigated.

Acetylcholine↗
PubMed1998

Analysis of glucuronolactone and glucuronic acid in drug formulations by high-performance liquid chromatography.

Glucuronolactone and glucuronic acid in drug formulations and beverages are determined as 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatives using high-performance liquid chromatography. Intra-ester linkage (i.e., the lactone of glucuronolactone) is spontaneously hydrolyzed to free-acid form and is analyzed as the PMP derivative of glucuronic acid. By omitting three evaporation steps in the original derivatization procedure, the total analysis time is shortened to approximately 40 min. Reproducibility of determination is within 4.0% for all drug formulations. The present method satisfies the requirements for routine analysis in the quality control of drug formulations containing glucuronolactone or glucuronic acid.

Antipyrine↗
PubMed1998

Growth patterns and genetic changes of colorectal carcinoma.

BACKGROUND: Recent Japanese studies have shown that histogenesis of small colorectal carcinomas can be divided into two groups: polypoid growth arising from polypoid neoplasia, and nonpolypoid growth arising from flat or depressed neoplasia. This classification should be verified with genetic as well as morphologic characteristics. SUBJECTS AND METHODS: In order to classify our subject into polypoid growth and nonpolypoid growth types both histologically and endoscopically, we selected 42 colorectal carcinomas < 2 cm in size (35 submucosal and seven more advanced). Clinicopathological findings, presence or absence of Ki-ras gene mutation and overexpression of p53 protein were compared between the two types. RESULTS: Histologically, the cases were divided into 27 of the polypoid growth type and 15 of the nonpolypoid growth type. None of the nonpolypoid growth cases contained adenomatous remnant, wheras this was found in 75% of the polypoid growth cases. No Ki-ras mutation was observed in any of the nonpolypoid growth cases, although it appeared in 44% of the polypoid growth cases. Regarding the overexpression of p53 protein, no significant difference was observed between the two types. The histological and the colonoscopic polypoid growth-nonpolypoid growth classifications correlated well with each other (agreement rate 98%), except for one lesion, which was classified as polypoid growth type endoscopically but as nonpolypoid growth type histologically. CONCLUSIONS: The histologically defined polypoid growth-nonpolypoid growth classification may indicate a difference in pathway of colorectal carcinogenesis. Also, colonoscopic polypoid growth-nonpolypoid growth classification is available for preoperative estimation of the genetic characteristics of small carcinomas.

Adenoma↗
PubMed1998

Giant cell tumor of bone: oncological and functional results of long-term follow-up.

BACKGROUND: Giant cell tumor (GCT) of bone is a rare and unpredictable lesion. Its standard treatment has ranged from surgical curettage to wide resection and varying oncological and functional results have been reported. METHODS: A retrospective review of 47 patients (17 males and 30 females) with GCT of bone was performed to evaluate the oncological and functional results. The patients were followed up for at least 5 years. The average age of the patients was 32 years (range 15-66 years). The tumor sites were distal femur in 15 cases, proximal tibia in 10, distal radius in five, spinal column in four, proximal femur in three, proximal humerus in three, proximal fibula in two, pelvis in two and others in three. Enneking's surgical stages were Stage 1 in three, Stage 2 in 34 and Stage 3 in 10 cases. In these 47 patients, 80 surgical procedures were performed. RESULTS: The rate of local recurrence was 75% in the 28 patients undergoing intralesional excision, 50% in those receiving excision and curettage and 0% in those receiving wide resection. Although there was no statistical significance, surgical stages tended to be correlated with the local recurrence rate (Stage 1, 0%; Stage 2, 53%; Stage 3, 70%). Functional evaluation was performed according to the most recent system of the Musculoskeletal Tumor Society. Functional results of the patients with extremity tumors were 28.2 (average) in those undergoing intralesional excision, 30 (average) in those receiving excision and curettage and 27.1 (average) in those receiving wide resection. Functional results were significantly correlated with the initial surgical stages (Stage 1, 30; Stage 2, 27.5; Stage 3, 24.4; Kruskal-Wallis test, P = 0.016). CONCLUSIONS: To preserve good function of the extremities and avoid local recurrence, we consider that intralesional excision with adjunctive therapy such as phenol cauterization should be employed for the treatment of benign GCT of bone.

Adolescent↗
PubMed1998

Diagnostic findings in endoscopic screening of superficial colorectal neoplasia: results from a prospective study.

BACKGROUND: A prospective study was carried out to clarify the efficacy of an endoscopic screening program for detecting superficial colorectal neoplasias by color changes such as faint redness or discoloration, which have been described as a key finding of these lesions in the literature. METHODS: We enrolled 716 consecutive cases in this study, but more than half of them did not reveal any abnormalities colonoscopically. RESULTS: Of the 716 cases, 48 (7%) were examined by magnifying colonoscopy with a dye spraying technique, following the detection of superficial color changes. Sixteen neoplastic lesions (in 16 cases) were detected among the 48 cases and the detection rate was calculated as 2.2% (16/716) in the total number of cases and 33% (16/48) in those showing color abnormalities. Histologically, all of the 16 were adenomas. These neoplastic lesions were most frequent (52%; 11/21) in those showing faint redness in an oval shape, whereas 14 (94%) of the 15 lesions were non-specific in those showing faint redness with unclear margin. CONCLUSIONS: These results may confirm the diagnostic utility of color abnormality, particularly faint redness in an oval shape, for endoscopic screening of superficial colorectal neoplasias.

Adenoma↗
PubMed1998

Cyanocysteine-mediated molecular dissection of dihydrofolate reductase: occurrence of intra- and inter-molecular reactions forming a peptide bond.

During a cyanocysteine-mediated dissection study of dihydrofolate reductase, a peptide fragment with a molecular mass of 18 Da less than expected was found as a major reaction product when the dissection reaction was applied to a Lys-cyanocysteine linkage. Detailed characterization of the dissection products by protease digestion, peptide sequencing, liquid chromatography/electrospray ionization mass spectrometry, and capillary electrophoresis suggested that the by-product was generated via a lactam ring formation through the intramolecular nucleophilic attack of the epsilon-amino group on the carbonyl carbon of the Lys-cyanocysteine linkage. We have also demonstrated the occurrence of intermolecular attack of an alpha-amino group of glycine on the carbonyl carbon of the X-cyanocysteine linkage to form a new X-Gly linkage, which should be a useful reaction for specific modification of proteins at the C-terminal.

Binding Sites↗
PubMed1998

Bacterial croup caused by Pasteurella haemolytica.

We report a case of bacterial croup caused by Pasteurella haemolytica. A nine-month-old girl was admitted to our hospital because of abrupt onset dyspnea and unconsciousness. From clinical and laboratory findings, she was diagnosed as having bacterial croup. Pasteurella haemolytica was recovered from her tracheal secretion on admission. To our knowledge, this is the first report of bacterial croup caused by P. haemolytica.

Croup↗
PubMed1998

Evaluation of fluorescence polarization method for binding study in carbohydrate-lectin interaction.

The fluorescence polarization (FP) technique was evaluated to determine molecular interaction between plant lectins and polysaccharides, yeast cells and glycopeptide after labeling the lectins with fluorescein isothiocyanate. Use of Lycoris radiata agglutinin allowed determination of the molecular interactions with large biomolecules containing mannose oligomers and polymers. Another example using a fluorescein-labeled glycopeptide also indicated that use of the FP method would allow easy observation of the molecular interactions on the quantitative base. The present technique is highly sensitive and facile because it does not require any washing procedures before measurement.

Binding Sites↗