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Biomedical subjects

Y Kataoka

Publications and source records attributed to Y Kataoka.

At least 127 records · Page 7Linked to original sources
PubMed1996

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody against Streptococcus suis type 2 in infected pigs.

An ELISA test for the detection of antibody against S. suis type 2 in pigs was developed and applied to field sera. The best sensitivity and specificity of ELISA were obtained when a purified polysaccharide antigen was used. It showed no cross reaction with sera against other serotypes of S. suis and other pathogenic bacteria. A total of 264 sera were collected from 20 pig farms and examined with the antibody against S. suis type 2. In the affected farms, 17.0% of pigs tested were positive, 9.8% in the adjacent farms, but only 3.4% in the free farms. The difference of the positive percentages between the affected and the free farms was statistically significant (P < 0.05).

Animals↗
PubMed1996

Cell proliferation and renewal of mouse adrenal cortex.

Although many hypotheses concerning cell proliferation and renewal in the adrenal cortex of mammals have been proposed, this topic has so far not been elucidated. Adrenocortical cells of adult mammals have low proliferative activity and take a considerable length of time to be renewed. This makes it difficult to investigate the dynamic features of their proliferation. To clarify the cell kinetics, we undertook a long term study in mice using an autoradiographic technique. We radiolabelled almost all the cells throughout the body in newborn mice with the exception of the neurons in central nervous system by the frequent subcutaneous injections of [3H]thymidine every 6 h for 30 d (pulse labelling). After this sequence of pulse labelling, we observed autoradiographically a decrease in the number of 3H-labelled cells in the adrenal cortex as a result of replacement with proliferated unlabelled cells (renewed cells). Single injections of [3H]thymidine (flash labelling) was also performed to examine DNA synthesis in the adrenal cortex. The investigations indicated that the adrenocortical cells proliferate at the border between the zona glomerulosa and the zona fasciculata, and that renewed cells which proliferated in that region move with time bidirectionally towards the cortical surface and the inner (medullary) surface. Half of the cortical cells in the zona glomerulosa, zona fasciculata and zona reticularis were replaced by renewed cells in 30, 60 and 120 d respectively. It took 200 d for almost all cortical cells to be replaced by renewed cells.

Adrenal Cortex↗
PubMed1996

Effect of hyperbaric oxygenation on bone in HEBP-induced rachitic rats.

The effect of hyperbaric oxygenation (HBO) treatment on rachitic change was studied using 4-wk-old, 1-hydroxyethylidene-1, 1-bisphosphonic acid disodium (HEBP-EHDP)-induced rachitic rats. After treatment, the dry weight, ash weight, Ca and P content, and bone mineral density of the hind leg bones were measured in each rat. These parameters were significantly increased in the rats that were treated with HBO after HEBP administration compared with those parameters in the rats that received HEBP alone. However, there was no significant differences between the rats treated simultaneously with HEBP and HBO and those that were treated with HEBP alone. These results were consistent with radiologic and histologic findings. Marked calcification in the center of the growth plate was revealed in the rats treated with HBO after HEBP administration. We suggest that intermittent high-pressure pure oxygen has a beneficial effect on osteogenesis in rachitic bone but does not prevent rachitic change.

Animals↗
PubMed1996

Antimutagenic effects of amifostine: clinical implications.

The radioprotector S-2-(3-aminopropylamino) ethylphosphorothioic acid (amifostine; WR-2721) was evaluated for its ability to protect against cyclophosphamide-induced mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in mouse splenocytes under conditions that do not interfere with cyclophosphamide's therapeutic effectiveness against fibrosarcoma lung tumors. Mutations at the HPRT locus increase in frequency as a function of the dose of cyclophosphamide used. With a spontaneous mutation frequency in C3H mice of 1.5 x 10(-6), mutation frequencies increased from 6.2 x 10(-6) to 2.0 x 10(-5) as the cyclophosphamide dose increased from 50 to 200 mg/kg. C3H male mice had 3.5 x 10(5) viable fibrosarcoma cells injected into their tail veins. This resulted in an average of 68 tumor colonies per mouse. Four days following injection, animals received cyclophosphamide 100 mg/kg, which provided significant tumor cell killing and a reduction in tumor colony number to an average of less than one per animal. Amifostine at a concentration of 100 mg/kg did not affect cyclophosphamide's therapeutic efficacy. However, amifostine 100 mg/kg was effective in reducing cyclophosphamide-induced HPRT mutation frequency in mice from 160 to 35 per 10(5) viable cells regardless of whether it was administered 30 minutes before or 2 hours after the cyclophosphamide.

Amifostine↗
PubMed1995

Contribution of L-type Ca2+ channels to long-term enhancement of high K(+)-evoked release of dopamine from rat striatal slices.

Pre-treatment with BAY K 8644, an L-type voltage-gated Ca2+ channels agonist, produced long-term enhancement (LTE) of over 2 h of high K(+)-evoked dopamine release from rat striatal slices. Exposure to BAY K 8644 under Ca(2+)-free conditions did not enhance this release. Thus, a transient activation of L-type voltage-gated Ca2+ channels followed by Ca2+ entry can trigger LTE of the evoked DA release from striatal tissues. This type of LTE in the striatum underlines the importance of presynaptic mechanisms, including L-type voltage-gated Ca2+ channels of 'long-term potentiation' expression.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1995

NMDA receptor involvement in endothelin neurotoxicity in rat striatal slices.

The high K(+)-evoked dopamine release from rat striatal slices remained impaired by 50% up to 2 h after pulse exposure of the tissues to endothelin-3, under conditions of hypoglycemia/hypoxia. This striatal dysfunction was significantly improved by D-2-amino-5-phosphonopentanoic acid, a NMDA receptor antagonist, at a much lower concentration than that providing protection against NMDA-evoked dysfunction. In light of these findings, the important role of glutamatergic mechanisms, especially NMDA receptors, in mediating endothelin neurotoxicity warrants further attention.

2-Amino-5-phosphonovalerate↗
PubMed1995

Long-term results of intertrochanteric varus osteotomy for arthrosis of the dysplastic hip (over 10 years' follow-up).

We performed a retrospective clinical and radiographic review of the long-term results of 64 hips in 53 patients who underwent intertrochanteric varus osteotomy for arthrosis of the hip at the pre- or early stage with acetabular dysplasia. Their average age at operation was 26 years. The average duration of follow-up was 18 years and 10 months. The mean Harris hip score was 77 +/- 9 points pre-operatively, and improved significantly to 84 +/- 13 points at the final follow-up. The acetabular coverage influenced the final outcome, and the postoperative prognosis was predictable from the acetabular head index (AHI) on a pre-operatively done hip maximum abduction radiograph (abd XP). We conclude that varus osteotomy for a dysplastic hip should be considered when the acetabular coverage is sufficient, and that a good prognosis can be expected when AHI on abd XP is greater than 60%.

Adolescent↗
PubMed1995

Nondetectable S-cone electroretinogram in a patient with crystalline retinopathy.

We examined cone and rod electroretinograms to ganzfeld stimuli in a patient with crystalline retinopathy. The 54-year-old man complained of night blindness, blurred vision, and metamorphopsia in both eyes. His visual acuity was 10/200 in the right eye and 10/20 in the left eye; his subjective dark-adaptation threshold was elevated 1 log unit, and he made one tritan error on the Farnsworth Panel D-15. Specular microscopic examinations revealed tiny crystalline deposits in the limbal cornea bilaterally. Ophthalmoscopically, crystalline deposits were found in the posterior fundi. His light-adapted cone electroretinograms to white stimuli were diminished (about 30% of those of normal controls), with normal implicit times. His dark-adapted rod electroretinogram amplitudes were 10% of those of normal controls. The S-cone electroretinogram was not detectable to different spectral stimuli with strong white background, while the L-M-cone responses appeared normal in waveforms with reduced amplitude. These ERG results indicated that the patient's S-cone system is more highly impaired than the L-M-cone system, supporting the psychophysical evidence that the S-cone system is more vulnerable than other cone systems in retinal diseases.

Dark Adaptation↗
PubMed1995

Time course of nitric oxide synthase activity in neuronal, glial, and endothelial cells of rat striatum following focal cerebral ischemia.

1. The time course of nitric oxide synthase (NOS) activity in neuronal, endothelial, and glial cells in the rat striatum after middle cerebral artery (MCA) occlusion and reperfusion was examined using a histochemical NADPH-diaphorase staining method. 2. In sham-operated rats, neuronal cells of the striatum exhibited strong NADPH-diaphorase activities. When rats were subjected to MCA occlusion for 1 hr, neuronal damage, including neurons with positive NADPH-diaphorase activities, appeared in the striatum at 3 hr after and extended to all areas of the striatum 3-4 days after reperfusion. 3. NADPH-diaphorase activities in the endothelial cells increased in the damaged part of striatum from 3 hr after, peaked at 1-2 days after MCA occlusion/reperfusion, then gradually decreased. 4. In parallel with the development of neuronal damage, some astrocytes and a high proportion of microglia/macrophages located in the perisite and in the center of the damaged striatum, respectively, exhibited a moderate to high level of NADPH-diaphorase activities. Most of these activities disappeared at 4 days after MCA occlusion. 5. These findings provided evidence that an inappropriate activation of NOS in endothelial cells and microglia/macrophages, in response to MCA occlusion/reperfusion, is closely associated with initiation and progression of ischemic neuronal injury in the striatum.

Animals↗
PubMed1995

Ephedrine-induced increases in arterial blood pressure accelerate regression of epidural block.

We investigated the hypothesis that ephedrine-induced increases in blood pressure accelerate the regression of epidural block. In patients undergoing minor gynecologic surgery, we performed lumbar epidural blockade using 2% lidocaine containing 1:200,000 epinephrine to which was added 0.1 mg of fentanyl. Eighty minutes after the epidural injection, we started an ephedrine infusion to increase the systolic blood pressure by 20% in 10 min and maintained the value for the following 20 min. Then we compared the proximal extent of sensory analgesia at 80 min with that at 140 min. Ephedrine significantly (P = 0.001) hastened the regression of sensory analgesia. We conclude that an ephedrine-induced blood pressure increase accelerates regression of epidural blockade.

Adjuvants, Anesthesia↗
PubMed1995

Glial endothelin/nitric oxide system participates in hippocampus CA1 neuronal death of SHRSP following transient forebrain ischaemia.

1. When delayed neuronal death occurred in the hippocampus CA1 pyramidal cell layer of stroke-prone spontaneously hypertensive rats (SHRSP) at 4 and 7 days after a 10 min bilateral carotid occlusion and reperfusion, intense endothelin-1 (ET-1)- and ET-3-like immunoreactivities became evident in astrocytes in the damaged hippocampus CA1 subfields. 2. We also observed that microglia equipped with an ETB receptor aggregated within the CA1 pyramidal cell layer with neuronal death. 3. There was a dramatic increase in nitric oxide synthase (NOS) activity in astrocytes and microglia in the damaged hippocampus CA1 subfields. 4. Thus, the possibility that microglia with the ETB receptor are activated to produce NO, a neurotoxic factor, by astrocytic ET-1 and ET-3 produced in response to transient forebrain ischaemia would have to be considered.

Animals↗
PubMed1995

Inhibitory action of nebracetam on various stimuli-evoked increases in intracellular Ca2+ concentrations in cultured rat cerebellar granule cells.

Nebracetam (10-100 microM) dose-dependently inhibited increases in intracellular Ca2+ concentrations evoked by various stimuli in cultured rat cerebellar granule cells. The magnitude of the nebracetam (100 microM)-induced inhibition of L-glutamate- and N-methyl-D-aspartate-evoked Ca2+ responses was 1.5-fold and 1.7-fold greater, respectively, than the inhibition of the high K(+)-evoked response. These findings suggest that in cultured cerebellar granule cells, nebracetam attenuates the external Ca2+ influx derived from the activation of N-methyl-D-aspartate receptor-gated rather than voltage-gated Ca2+ channels.

Animals↗
PubMed1995

Histological evidence for neuroprotective action of nebracetam on ischemic neuronal injury in the hippocampus of stroke-prone spontaneously hypertensive rats.

The protective effect of nebracetam on ischemic neuronal damage was histologically examined in the pyramidal cell layer of the hippocampal CA1 subfield 7 days after operation using stroke-prone spontaneously hypertensive rats (SHRSP) subjected to 10-min bilateral carotid occlusion. Nebracetam (50 and 100 mg/kg), given orally 10 min after reperfusion, dose-dependently protected against ischemic delayed neuronal damage in the SHRSP with occlusion; however, the blood pressure remained unchanged following nebracetam administration. These findings further support the notion that nebracetam protects against ischemic delayed neuronal cell death in the hippocampus.

Animals↗
PubMed1995

[Adherence to HEp-2 cells of enterotoxemic Escherichia coli O-group 139 from pigs with edema disease].

One hundred and one strains of enterotoxemic Escherichia coli (ETEEC) O-group 139 isolated from swine with edema disease were investigated for their adherence to HEp-2 cells in the presence of D-mannose. All strains adhered in large numbers to the cells (21 to 60 bacteria/cell). No correlation was found between the presence of F107 fimbria on the organisms and the adherence to the cells. Adhesion-inhibition tests showed that anti-K12 serum inhibited the adhesion ETEEC O-group 139 (an inhibition rate of 63 to 65%), but anti-F107 or anti-O139 sera did not. These results indicate that the capsular K12 antigen may be one of the pathogenic factors of ETEEC O-group 139.

Animals↗
PubMed1995

[Coronary artery bypass surgery in patients aged 75 years or older].

16 patients 75 years of age or older underwent coronary artery bypass grafting. The overall hospital mortality rate was 12.5% (2/16), 0% for elective procedures, 33.3% for urgent and emergent cases. 4 of 6 patients underwent emergency CABG after failed percutaneous transluminal coronary angioplasty. Major complications were altered mental status, low cardiac output syndrome (LOS), pulmonary dysfunction and renal dysfunction. One patient who died had LOS. Another patient who died occurred multiple organ failure after pulmonary dysfunction from self-extubation. There was no correlation the incidence of postoperative confusion and preoperative cerebral CT findings. CABG can be performed safely in patients 75 years or older, if the preoperative conditions are stable.

Age Factors↗
PubMed1994

ETB receptor involvement in stimulatory and neurotoxic action of endothelin on dopamine neurones.

We examined the role of endothelin (ET) receptor subtypes in mediating the transient and sustained release of dopamine (DA) evoked by ETs and ET-1-induced dopaminergic dysfunction in rat striatal slices. Both phases of the release of DA evoked by ET-1 and ET-3 were inhibited by RES-701-1 (ETB antagonist) but not BQ-123 (ETA antagonist). The high K(+)-evoked DA release from slices remained impaired following a brief exposure to ET-1, under conditions of hypoxia/hypoglycaemia. RES-701-1 but not BQ-123 led to a recovery from ET-1-induced striatal dysfunction. Therefore, ETB receptors are involved in the stimulatory and neurotoxic actions of ETs on the striatal dopaminergic system.

Animals↗
PubMed1994

Antianxiety actions of Ca2+ channel antagonists with Vogel-type conflict test in rats.

We examined the effects of various derivatives of Ca2+ channel antagonists in a modified rat Vogel-type conflict model. Flunarizine (10 and 20 mg/kg), nicardipine (20 mg/kg), and verapamil (20 mg/kg), given as single i.p. injections, significantly increased punished lickings by 50-110%. Chronic administration of diltiazem, at 20 mg/kg i.p. for 8 days, a dose ineffective with a single i.p. injection, produced a significant anticonflict action. The possibility that Ca2+ channel antagonists have anxiolytic action should be considered.

Animals↗