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Biomedical subjects

Y Kataoka

Publications and source records attributed to Y Kataoka.

At least 19 recordsLinked to original sources
PubMed1998

Determination of salicylic acid in human serum with capillary zone electrophoresis.

The determination of salicylic acid (SA), a metabolite of aspirin, in human serum was developed using capillary zone electrophoresis (CZE) with diode array detection. The reproducibility of separation and quantification with CZE analysis of the extract of SA from human serum was appropriate for the intra- and inter-day assay coefficients. A high correlation was revealed between the serum SA levels in volunteers determined by CZE and those determined by a fluorescence polarization immunoassay (r=0.973, n = 12), although the former values were slightly higher than the latter. There were no peaks interfering with the assay of SA by internal standard method. This CZE method could provide a simple and efficient method for monitoring SA in patients.

Administration, Oral↗
PubMed1998

Enhancement of serotonergic neural activity contributes to cyclosporine-induced tremors in mice.

A single cyclosporine injection (50 mg/kg, i.p.) significantly enhanced harmine- but not oxotremorine-induced tremors in mice. This potentiation became more apparent when cyclosporine (50 mg/kg, i.p.) was administered once a day for seven days. These findings suggest an involvement of monoaminergic mechanisms in cyclosporine-induced tremors. The effects of cyclosporine were examined on the dynamics of noradrenaline, dopamine and serotonin in the mouse brain. Both single and repeated treatment with cyclosporine significantly facilitated the serotonin turnover as estimated from the probenecid-induced accumulation of 5-hydroxyindoleacetic acid, but either mode of treatment failed to change the contents of monoamines and their metabolites or the turnover of noradrenaline and dopamine. Therefore, the cyclosporine-enhanced activity of serotonin neurons may be interpreted as producing adverse central effects, including tremors.

Animals↗
PubMed1998

Enhancement of replication of genetically engineered herpes simplex viruses by ionizing radiation: a new paradigm for destruction of therapeutically intractable tumors.

Human U-87 malignant glioma xenografts in mice were exposed to ionizing radiation, inoculated with a herpes simplex virus 1 mutant R3616 lacking both copies of the gamma 34.5 gene, or received both virus and radiation. Dual treatment caused a significantly greater reduction in volume or total regression of tumors than either radiation or infection alone. The significantly enhanced oncolytic effects of the combined treatment correlate with two-to five-fold enhanced replication in irradiated tumor cells than in tumors receiving virus only. In addition, in situ hybridization with viral DNA probes showed that infected tumor cells were the dominant landscape of irradiated tumors and much less apparent in the nonirradiated tumors administered this virus.

Animals↗
PubMed1998

Biochemical and serological examination of beta-hemolytic streptococci isolated from slaughtered pigs.

A total of 170 beta-hemolytic streptococci isolated from lesions in slaughtered pigs during 1988 to 1995 were identified by biochemical and serological examinations. Of these, 132 strains (77.6%) were Streptococcus (S.) dysgalactiae and 38 strains (22.4%) were S. porcinus. The largest serological group of streptococci was group C (78 strains, 45.9%), followed by group L (43 strains, 25.3%), group U (14 strains, 8.2%), group G (11 strains, 6.5%), group E (5 strains, 2.9%), and group P (5 strains, 2.9%). Most of isolates from endocarditis (61 strains) and arthritis (25 strains) were group C S. dysgalactiae, but about 33.3% of the isolates from lymphadenitis were group L S. dysgalactiae (28 strains), followed by group C (14 strains, 16.7%), group U S. porcinus (14 strains, 14.3%), and group G (10 strains, 11.9%).

Abattoirs↗
PubMed1997

Application of high-performance thin-layer chromatography for the detection of organophosphorus insecticides in human serum after acute poisoning.

We developed a rapid and simple method for identifying 25 commonly used organophosphorus insecticides in human serum using high-performance thin-layer chromatography (HPTLC). These organophosphates were separated on plates with three different developing systems within 6-18 min and detected by means of ultraviolet radiation and coloring reactions with 4-(4-nitrobenzyl)pyridine-tetraethylenepentamine reagent (NT reagent) or palladium chloride reagent (PdCl2 reagent). Each organophosphate was accurately identified by means of the R(F) x 100 value and the spot color in three systems. The detection limits of dichlorvos, fenitrothion, malathion, methidathion, parathion and trichlorfon in serum by the liquid-liquid extraction method were 1.1, 0.12, 0.12, 0.05, 0.6 and 0.1 microg/ml, respectively. These sensitivities may be sufficient to detect those organophosphates in patient serum after acute poisoning.

Chromatography, High Pressure Liquid↗
PubMed1997

Propofol produces anticonflict action by inhibiting 5-HT release in rat dorsal hippocampus.

We examined the effect of propofol, an injectable anesthetic agent on conflict behavior in a Vogel type conflict test and on release of serotonin (5-hydroxytryptamine, 5-HT) in the dorsal hippocampus using an in vivo microdialysis method in rats. Propofol (20 and 40 mg/kg, i.p.) dose-dependently suppressed elevated 5-HT release normally seen in a conflict situation and concomitantly attenuated conflict behavior. These findings suggest that propofol exerts an antianxiety action by inhibiting 5-HT neuronal activity in the dorsal hippocampus.

Anesthetics, Intravenous↗
PubMed1997

A postsynaptic excitatory amino acid transporter with chloride conductance functionally regulated by neuronal activity in cerebellar Purkinje cells.

Excitatory amino acid (EAA) neurotransmitters induce postsynaptic depolarization by activating receptor-mediated cation conductances, a process known to underlie changes in synaptic efficacy. Using a patch-clamp method, we demonstrate here an EAA-dependent postsynaptic anion conductance mediated by EAA transporters present on cerebellar Purkinje cell bodies and dendrites in culture. This transporter-mediated current was modulated by neuronal activity: it exhibited facilitation for >20 min after transient depolarization accompanied by Ca2+ influx. Evidence is presented suggesting that the transporter facilitation is mediated by arachidonate release after Ca2+-dependent activation of phospholipase A2, which exists in Purkinje cells. This postsynaptic reuptake system may represent a novel modulatory mechanism of synaptic transmission as well as prevent neuronal excitotoxicity.

Animals↗
PubMed1997

Micellar electrokinetic capillary chromatography for therapeutic drug monitoring of zonisamide.

The simultaneous determination of zonisamide, a new type of antiepileptic drug, and the typical antiepileptic drugs phenobarbital, phenytoin and carbamazepine in human serum was developed using micellar electrokinetic capillary chromatography (MECC) with a diode array detector. A high correlation was revealed between the zonisamide levels in human serum obtained by MECC and those obtained by high-performance liquid chromatography (r=0.981). The serum levels of phenobarbital, phenytoin and carbamazepine determined by MECC were almost equal to those obtained by fluorescence polarization immunoassay. The reproducibility of separation and quantification with MECC analysis was appropriate for the intra- and inter-day assay coefficients. Therefore, the MECC method established here could provide a simple and efficient therapeutic drug monitoring method for antiepileptic drugs in patients, especially those treated with a combination of zonisamide and other antiepileptic drugs.

Anticonvulsants↗
PubMed1997

Expression of endothelin receptors and nitric oxide synthase in the brain of stroke-prone spontaneously hypertensive rats with cerebral apoplexy.

Endothelin (ET) receptors, ET-1-like immunoreactivity and nitric oxide synthase (NOS) were examined in the brain of stroke-prone spontaneously hypertensive rats (SHRSPs) with cerebral apoplexy. Our receptor autoradiographic method with 125I-ET-1 and unlabeled selective ligands for ET receptors revealed de novo expressions of ET(A) and ET(B) receptors in areas of neural lesions with cerebrovascular damage in SHRSPs. Immunohistochemical staining for ET-1 showed clear ET-1-like immunoreactivity in areas with highly expressed ET receptors. Histochemical studies on astrocytes and microglia suggested that these glial cells, aggregating in lesions, may carry ET receptors, ET-1-like immunoreactivity. Furthermore, NOS detected histochemically using an NADPH-diaphorase staining method was rich on glial cells in damaged areas of the brain in SHRSPs with cerebral apoplexy. Our data suggest the pathophysiological significance of glial ET(A) and ET(B) receptors, ET-1 and NOS in neural lesions of SHRSPs.

Animals↗
PubMed1997

Repeated interferon-alpha administration inhibits dopaminergic neural activity in the mouse brain.

In vivo effects of single and repeated interferon-alpha administrations on the dynamics of noradrenaline, dopamine and 5-hydroxytryptamine were investigated in the mouse brain. Single interferon-alpha administration (15, 30 and 60 X 10(6) U/kg i.p.) had no significant effect on the levels of monoamines and their metabolites or monoamine turnover. When interferon-alpha (15 X 10(6) U/kg i.p.) was administered once a day for 5 days, however, both dopamine and 3,4-dihydroxyphenylacetic acid levels were significantly decreased and alpha-methyl-p-tyrosine-induced dopamine depletion was significantly suppressed. These results suggest that repeated interferon-alpha administration inhibits dopaminergic neural activity. This inhibitory action of interferon-alpha in dopamine neurons may be involved in adverse central effects, such as parkinsonism and depression with suicidal potential.

Animals↗
PubMed1997

Endothelin receptors in kainic acid-induced neural lesions of rat brain.

Seven days after an intracerebroventricular injection of 0.8 microgram kainic acid, a time of neural tissue-repair after damage, we applied our receptor autoradiographic method to examine changes in the endothelin receptors in kainic acid-induced neural lesions of the rat brain. There were belt-shaped areas with the de novo expressed [125I]endothelin-1 binding sites in the damaged hippocampus CA1, CA3, and CA4 subfields. We also noted a homogeneous zone with a low binding-density, the area sandwiched by the belt-shaped areas. In a "remote" area corresponding anatomically to the deep soma layer of the piriform cortex plus lateral parts of amygdaloid complex we noted a well-defined area with "punched hole-figure" of low density [125I]endothelin-1 binding sites. The lesion was surrounded by areas rich in binding sites. The de novo expressed [125I]endothelin-1 binding sites were characterized endothelin B receptor. Microglia were present in the area with "punched hole-figure" and in the hippocampus pyramidal cell layer with neuronal death. In contrast to microglia, astrocytes were rich with hypertrophia in kainic acid-induced neural lesions anatomically corresponding to areas with the de novo endothelin B receptor. Taken together with the present observations of microscopic evidence of cellular distribution, we suggest that the de novo expressed endothelin B receptor was carried by astrocytes aggregating in neural lesions. In light of our findings, the possibility that astrocytes can be activated by the endothelin B receptor in response to neural tissue repair after damage to neurons would have to be considered.

Animals↗
PubMed1997

Prion protein is necessary for latent learning and long-term memory retention.

1. The cellular prion protein, designated PrPc, is a key molecule in the prion diseases but its physiological function remains unknown. To elucidate whether PrPc plays some role in the central nervous system, we established a line of mice in which the PrP gene had been disrupted and subsequently conducted long-term observations. 2. Performance in latent learning and passive avoidance was evaluated using water-finding and step-through tests, respectively. 3. PrP-/- mice showed impaired performance in the water-finding test, indicating a disturbance in latent learning, at 23 weeks of age. In the step-through test, although the PrP-/- mice showed normal learning ability and short-term memory retention, they evidenced a significant disturbance in long-term memory retention. 4. These results indicate that PrPc is needed for certain types of learning and memory and that the loss of function of this protein may contribute to the pathogenesis of prion diseases.

Animals↗
PubMed1997

Nitric oxide participates in the stimulatory and neurotoxic action of endothelin on rat striatal dopaminergic neurons.

1. Our method of real-time monitoring of dopamine release from rat striatal slices revealed that endothelin (ET)-3-induced dopamine release was inhibited by NG-methyl-L-arginine (L-NMMA; 1 mM), an inhibitor of nitric oxide (NO) synthase, while NG-methyl-D-arginine (D-NMMA; 1 mM), an inactive isomer of L-NMMA, had no effect. 2. The inhibition of L-NMMA (0.1 mM) became apparent when tissues were pretreated with tetrodotoxin (1 microM) for 30 min and subsequently exposed to ET-3 (4 microM). 3. L-NMMA (0.1 and 1 mM) dose dependently protected against ET-3-triggered hypoxic/hypoglycemic impairment of striatal responses to high K+. 4. Thus, NO may work as a promoter in mediation of the stimulatory and neurotoxic action of ET-3 on the striatal dopaminergic system, presumably by interacting with interneurons in the striatum.

Animals↗
PubMed1997

Differences in hormonal responses to preoperative emotional stress between preschool and school children.

BACKGROUND: The behavior of children under emotional stress differs according to whether they are of preschool or school age. METHODS: To examine the effect of age on hormonal responses to preoperative emotional stress, we measured the concentrations of catecholamines (adrenaline and noradrenaline) and cortisol in 56 healthy boys before surgery. RESULTS: Among preschool boys (3-5 years old), those showing anxious behavior showed significantly higher cortisol, adrenaline, and noradrenaline concentrations in the blood circulation than those not showing such behavior (P < 0.0001, P < 0.0001 and P < 0.005, respectively). However, among the schoolboys (6-11 years old), anxiety was associated only with the cortisol concentration (P < 0.01). CONCLUSION: Hormonal responses to preoperative emotional stress in preschool boys differ from those in schoolboys.

Age Factors↗
PubMed1997

Essential roles of the winged helix transcription factor MFH-1 in aortic arch patterning and skeletogenesis.

Mesenchyme Fork Head-1 (MFH-1) is a forkhead (also called winged helix) transcription factor defined by a common 100-amino acid DNA-binding domain. MFH-1 is expressed in non-notochordal mesoderm in the prospective trunk region and in cephalic neural-crest and cephalic mesoderm-derived mesenchymal cells in the prechordal region of early embryos. Subsequently, strong expression is localized in developing cartilaginous tissues, kidney and dorsal aortas. To investigate the developmental roles of MFH-1 during embryogenesis, mice lacking the MFH-1 locus were generated by targeted mutagenesis. MFH-1-deficient mice died embryonically and perinatally, and exhibited interrupted aortic arch and skeletal defects in the neurocranium and the vertebral column. Interruption of the aortic arch seen in the mutant mice was the same as in human congenital anomalies. These results suggest that MFH-1 has indispensable roles during the extensive remodeling of the aortic arch in neural-crest-derived cells and in skeletogenesis in cells derived from the neural crest and the mesoderm.

Animals↗
PubMed1997

Enhancement by morphine of radiographic contrast media-induced histamine release in rat peritoneal mast cells.

In intravascular application of radiographic contrast media causes hypersensitivity reactions, in which histamine release may play a major role. We examined the interaction between contrast medium and morphine. Among the four nonionic contrast media examined, iopamidol showed the most marked histamine release from rat peritoneal mast cells in vitro. Although iopamidol and morphine themselves did not induce histamine release at concentrations up to 65 mgI/ml and 3 mM, respectively, their combination resulted in a significant histamine release. These findings suggest that patients with exposure to medicines that induce histamine release may have a higher incidence and severity of hypersensitivity reactions to radiographic contrast media.

Animals↗
PubMed1997

Characteristics of nucleotide sequences flanking the trans-spliced leader SL1 exon in Dirofilaria immitis, Brugia malayi, and Brugia pahangi.

Nucleotide sequences surrounding the trans-spliced leader SL1 exon in the 5S rRNA gene spacer regions of Dirofilaria immitis, Brugia malayi, and B. pahangi were determined after PCR amplification, aligned with the genus Onchocerca for comparison, and used for the prediction of secondary structures. The nucleotide sequence of this region in B. pahangi was first shown in the present study. Hypothetical secondary structures of the spacer region suggested that the SL1 transcript is capable to form a stable stem-loop structure which may render transposition of the SL1 sequence to mRNA molecules. A homologous sequence to Sm-binding site was assigned on a bulge loop. No significant difference was observed in adult worms of D. immitis irrespective of sex or location. No difference was apparent between the two species in genus Brugia.

Animals↗