Search PubMed⌕ Search

Biomedical subjects

H Miyata

Publications and source records attributed to H Miyata.

At least 163 records · Page 9Linked to original sources
PubMed1998

Prevention of vestibular deafferentation-induced spontaneous nystagmus with pretreatment of Ca2+ channel/N-methyl-D-aspartic acid receptor antagonists in guinea pigs.

Involvement of Ca2+ channel and N-methyl-D-aspartic acid (NMDA) receptors with induction of the spontaneous nystagmus (SN) after unilateral labyrinthectomy (UL) was evaluated by examining the effect of verapamil and MK-801 in guinea pigs. An injection of verapamil or MK-801 before the intratympanic application of arsanilate significantly (p < 0.05) suppressed the frequency of the SN towards the arsanilate-applied side. The frequency of the SN towards the intact side in these drug-treated animals was much lower than in the control animals until 36 h after the application of arsanilate. In addition, 60 days subsequent to induction of the UL, application of the drug before we injected the arsanilate into the opposite middle ear suppressed the SN towards the second arsanilate-injected side, but not towards the first injection side. We suggest that Ca2+ channel and NMDA receptor may be involved in the induction of the SN, and that the pretreatment of their antagonists could be applied in preventing the vestibular deafferentation-induced SN.

Animals↗
PubMed1998

[Retropharyngeal abscess in an adult and an elderly woman].

Retropharyngeal abscess is reported to be decreasing in frequency in recent years. We report two cases of retropharyngeal abscess that were diagnosed within four years in Department of Otorhinolaryngology, Gifu University Hospital. Case 1 was a 36-year-old male who was suggested to have an abscess as primary infection and case 2 was a 71-year-old female whose abscess seemed to be a secondary infection following unknown primary infection. Endoscopic or open neck drainage as well as antibacterial chemotherapy mainly with combinations of flomoxef and clindamycin in the case 1 and piperacillin and clindamycin in the case 2 was successfully carried out. They were discharged an 15-day and 24-day after operation in the cases 1 and 2, respectively. A 30 min. culture after sample collection on operation demonstrated aerobe-anaerobe mixed infection in both cases; three aerobes and four anaerobes in the case 1 and three aerobes and two anaerobes in the case 2. These results suggest that retropharyngeal abscess may be a complicated infection involving more bacterial species than has been commonly believed. Measuring susceptibility of isolates to antimicrobial agents, a strain of Capnocytophaga sp. and a strain of anaerobic gram-negative rod were highly resistant to piperacillin, cefroxine and ofloxacin. It is important for adequate antibacterial chemotherapy to grasp the bacteriology of retropharyngeal abscess and analyze susceptibility of antimicrobial agents.

Adult↗
PubMed1998

Upregulation of retinal vascular endothelial growth factor mRNAs in spontaneously diabetic rats without ophthalmoscopic retinopathy. A possible participation of advanced glycation end products in the development of the early phase of diabetic retinopathy.

Vascular endothelial growth factor (VEGF) has recently been shown to be involved in the pathogenesis of proliferative diabetic retinopathy. However, its involvement in the development of the early phase of diabetic retinopathy is not fully understood. In this study we investigated the retinal VEGF mRNA level in spontaneously diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats, a model of non-insulin-dependent diabetes, without overt retinopathy, using quantitative reverse-transcription polymerase chain reaction. The retinal VEGF mRNA level was 2.2 times higher (p < 0.0005) in OLETF rats than in control rats at the age of 60 weeks. Moreover, their retinal mRNA level was positively correlated with serum concentration of advanced glycation end products (AGEs) but not to serum glucose concentration. Furthermore, the peak latency of the oscillatory potentials in the electroretinogram, one of the most sensitive markers for the early phase of diabetic retinopathy, was significantly prolonged in OLETF rats (p < 0.05), being also correlated with the serum AGE concentration. The results thus suggest that AGEs, which are formed acceleratedly in diabetic conditions, are involved in the development of the early phase of diabetic retinopathy probably through the induction of retinal VEGF mRNAs.

Animals↗
PubMed1998

Genetic characterization of parainfluenza virus 3 derived from guinea pigs.

To understand the relationship between novel parainfluenza virus 3 (PIV-3), which has recently been isolated from the lungs of guinea pigs, and other PIV-3 strains, we determined the complete nucleotide sequence of the novel PIV-3 (GPv) genome. A comparison of the nucleotide sequence among PIV-3s, including bovine PIV-3, revealed that GPv is closely related to human PIV-3. The results of the phylogenetic analysis clearly showed that GPv is a lineage of human PIV-3, suggesting that GPv has probably been introduced into guinea pig colonies via infected humans.

Animals↗
PubMed1998

Patients' understanding and opinion about informed consent for coronary angiography in a rural Japanese hospital.

Based on an anonymous questionnaire obtained from 102 Japanese in-patients at a rural Japanese hospital who underwent coronary angiography, the patients understanding of information about the procedure, their perception of consent and their attitude toward it were investigated. The patients were able to recall 63.8% of the contents of the information. There was a statistically significant correlation between the patients' educational status and the recall test score of the information. Older (65 years old and above) patients had a tendency to entrust decision making to their physicians. Only 19.6% of the patients made the decision to undergo a coronary angiography by themselves. After being informed of the risks 40.2% of the patients felt more anxious. In conclusion, our patients could not recall the contents of the information sufficiently. There still existed a tendency to entrust important decisions to the physician especially in older patients. The patients had a tendency not to face difficult problems solely by themselves but with the support of family members.

Aged↗
PubMed1998

[An immunohistochemical study of RB tumor suppressor gene protein and bcl-2 gene protein in carcinomas of the thyroid gland].

The expression of RB and bcl-2 proteins was investigated in 135 thyroid carcinomas (130 papillary carcinomas and five follicular carcinomas) by the immunohistochemical technique with RB and bcl-2 monoclonal antibodies. The results were as follows: 1) RB protein nuclear staining was shown in 117 of the 135 thyroid carcinomas (87%). Bcl-2 protein staining was shown in 82 of the carcinomas (61%). 2) There was a higher incidence of recurrence in RB-negative cases than in RB-positive cases (chi 2 test p = 0.001). But there is no significant relationship between the incidence of recurrence and the results of bcl-2 staining (chi 2 test p = 0.287). 3) The expression of RB protein was related to age and clinical N and M categories. Bcl-2 protein expression was related to clinical T categories. 4) The 10-year overall survival rate for RB-positive patients was higher than that for negative patients (long-rank test p < 0.0001). But the survival rate was not associated with bcl-2 expression (log-rank test p = 0.3). Our results suggest that assessment of RB protein expression by the immunohistochemical technique may be useful to determine the possibility of recurrence and to predict the outcome of thyroid carcinomas. We think that assessment of RB protein expression by the immunohistochemical technique can be applied as a more sensitive prognostic factor.

Adenocarcinoma, Follicular↗
PubMed1998

[A study on the incidence of cerebral palsy among twins in Himeji City].

Twin delivery is associated with an increased risk of cerebral palsy. (CP). We studied the incidence of CP in twins compared with singletons born from 1989 to 1994 at the district of Himeji Central Public Health Center. The incidence of CP was 1.9% in twin: 12.7 times as high as that in singletons (0.15%), and was particularly high in monozygotic twins. Since circulatory changes specific for twin pregnancies may cause brain damage, careful obstetric management is recommended for monozygotic twins.

Cerebral Palsy↗
PubMed1998

[A study on the clinical features of cerebral palsy in twins].

We have studied the clinical features and neurological sequelae in 39 cases of cerebral palsy resulting from 30 twin births. Twenty-four births (80%) occurred before 37 weeks of gestation Among 30 twin pairs, co-twin with intrauterine death in 7 pairs, both patients showed neurological sequelae in 9 pairs and one of the twins developed cerebral palsy in 14 pairs. In 34 of the 39 cases, abnormal findings were revealed by MRI and/or CT. Periventricular leukomalacia was observed in 19 cases (55.9%), comprising 79.2% of the 24 preterm babies. The clinical features and MRI findings were variable among the term cases. These findings suggest that the pathogenesis of cerebral palsy is different between preterm and term cases.

Brain↗
PubMed1998

Biochemical properties of the superficial masseter muscle in the aging rat.

In young (15 weeks) and senescent (2 years) rats, the metabolic enzyme activities and the composition of myosin heavy chain (MHC) isoforms of the superficial masseter muscle were assessed by biochemical analysis. The succinate dehydrogenase activity and phosphofructokinase activity of the masseter muscle were significantly lower in senescent rats than in young rats. A large portion of the masseter muscle was composed of MHC IIb and IId isoforms in both young and senescent rats. As compared with young rats, no significant change in the composition of MHC isoforms was found in the masseter muscle of the senescent rats. These findings indicate that aging has a significant effect on the energy supply of the superficial masseter muscle.

Aging↗
PubMed1998

[Mechanism of nicotine dependence].

This article reviews the current studies on the mechanism of nicotine dependence. In the process of nicotine dependence, there are four major determinants: reinforcing effects, tolerance, craving and withdrawal. 1) The positive reinforcing effects of nicotine are important especially for the initiation of nicotine self-administration. These effects are considered to be induced by the ability of nicotine to promote the release of catecholamines, acetylcholine, beta-endorphine, glucocorticoid, and other kinds of hormones. 2) However, tolerance gradually develops to the positive reinforcing effects of nicotine, as nicotine is repeatedly self-administered. 3) Craving is defined as the uncontrollability of the urge to take drugs, which is a core aspect of recent ICD-10 or DSM-IV descriptions. Craving for nicotine is caused and enhanced by the following three factors; psychic withdrawal symptoms such as anxiety, depression and dysphoria, conditioning processes leading to the association of nicotine effects with environmental stimuli, and memory of the reinforcing effects of nicotine. 4) Neither somatic withdrawal symptoms nor mental disorders related to nicotine dependence is significant. 5) As for the neurobiology of nicotine dependence, the reward system is focused as a putative responsible region involved not only in the reinforcing effects of nicotine but also in the psychic withdrawal symptoms. The amygdala-nucleus accumbens connection may be intimately involved in the association between nicotine effects and environmental stimuli. And neuronal circuits involved in memory function may be implicated in the manifestation of craving and relapse, but the details remain to be solved.

Animals↗
PubMed1998

[Incidence of cerebral palsy in Himeji City 1983-1992].

We investigated the incidence of cerebral palsy (CP) in Himeji City with a total population of about 470,000. In 1983-87 the total number of CP patients and the incidence of CP per 1,000 live births were 40 and 1.4, respectively. In 1988-92, the figures were 51 and 2.0. Periventricular leukomalacia was indicated in MRI in 11 out of 40 cases (27.5%) in 1983-87, and in 25 out of 51 (49.0%) in 1988-92. These results suggest that the increase in the incidence of CP mainly depends on changes of medical care for neonates.

Birth Weight↗
PubMed1998

Evanescent excitation microscopy. Its application to the study of single molecular process kinetics of actomyosin motor.

Evanescent field was generated on the stage of an inverted microscope upon an incidence of 532 nm Nd-YAG laser beam on interface between aqueous solution and fused silica glass. Thick filaments isolated from Mytilus edulis were adsorbed to the glass surface and nanomolar concentration of adenosine triphosphate (ATP) labeled with rhodamine was allowed to interact with thick filaments. The fluorescence from the surface was observed by triple-view microscopy at video rate. There were many fluorescent spots at the interface, which we identified as individual fluorescent ATP molecules. We found that the fluorescence from those spots was polarized. Fluorescence intensity of individual spots fluctuated considerably. We interpret the latter observation as a result of change in the orientation of emission dipole of the fluorescent ATP analog.

Actomyosin↗
PubMed1997

Axial rotation of sliding actin filaments revealed by single-fluorophore imaging.

In the actomyosin motor, myosin slides along an actin filament that has a helical structure with a pitch of approximately 72 nm. Whether myosin precisely follows this helical track is an unanswered question bearing directly on the motor mechanism. Here, axial rotation of actin filaments sliding over myosin molecules fixed on a glass surface was visualized through fluorescence polarization imaging of individual tetramethylrhodamine fluorophores sparsely bound to the filaments. The filaments underwent one revolution per sliding distance of approximately 1 microm, which is much greater than the 72 nm pitch. Thus, myosin does not "walk" on the helical array of actin protomers; rather it "runs," skipping many protomers. Possible mechanisms involving sequential interaction of myosin with successive actin protomers are ruled out at least for the preparation described here in which the actin filaments ran rather slowly compared with other in vitro systems. The result also indicates that each "kick" of myosin is primarily along the axis of the actin filament. The successful, real-time observation of the changes in the orientation of a single fluorophore opens the possibility of detecting a conformational change(s) of a single protein molecule at the moment it functions.

Actins↗
PubMed1997

Apoptosis and in vivo distribution and clearance of eosinophils in normal and Trichinella spiralis-infected rats.

We examined apoptosis of eosinophils obtained from normal rats and rats infected with Trichinella spiralis (T. spiralis). A considerable percentage of normal rats underwent apoptosis within a few hours, however, the apoptosis rate of infected rats was significantly lower. This rate began decreasing only 12 h after infection, reached its lowest level on day 3, and was restored to normal by day 40. We also studied the effects on eosinophil apoptosis of culture supernatants from concanavalin A-stimulated spleen cells from infected rats and found that supernatants from days 3, 7, and 18 of infection inhibited apoptosis eosinophils from normal rats. We then examined the distribution and clearance of eosinophils in vivo. In normal rats, the largest numbers of eosinophils were found in the spleen, liver, and bone marrow. In the infected rats, however, by day 3, by which time the worms had begun to migrate, there was a striking increase in these cells in the intestines. In summary, normal eosinophils are unexpectedly sensitive to apoptosis, whereas infected eosinophils become resistant to this form of cell death.

Animals↗
PubMed1997

Successful treatment of an esophageal hemangioma by endoscopic injection sclerotherapy: report of a case.

We report herein the case of a 46-year-old man in whom an esophageal hemangioma was successfully treated by endoscopic injection sclerotherapy (EIS). The patient was admitted to hospital after a routine upper gastrointestinal series demonstrated a filling defect in the esophagus. Endoscopy, computed tomography (CT) images, and magnetic resonance imaging (MRI) subsequently revealed a hemangioma in the middle esophagus. EIS was performed using 99% ethanol and 1% polydocanol, and 4 weeks later, the tumor had almost disappeared. This patient has since been followed up carefully with periodic endoscopy and barium studies and additional sclerotherapy will be performed if necessary.

Esophageal Neoplasms↗
PubMed1997

Non-convulsive status epilepticus induced by antidepressants.

We report on a 27-year-old woman of non-convulsive status epilepticus (NSE) very probably induced by antidepressants. She has no history of febrile convulsions, or epileptic seizures. There are no genetic factors for epilepsy in her family. As she developed depressive illness, she consulted a doctor. Clomipramine 25 mg i.v. drip/day and maprotiline 75 mg/os/day were started. Recently she began to doze, so an EEG was performed. Continuous generalized 2-3 Hz spike and wave complexes were observed. Clomipramine and maprotiline were stopped the same day, and the patient's drowsiness gradually improved. There are some case reports of NSE induced by antidepressants. However, the patients in these reports had received frequent electroconvulsive therapy (ECT) and were middle aged and may have been affected by an organic brain disorder. The present patient was young, and had not received ECT. It is therefore very likely that antidepressants may have been responsible for the occurrence of NSE in this patient. It is concluded that NSE should be considered an adverse effect of any antidepressant.

Adult↗
PubMed1997

Sexual co-flocculation by heterothallic cells of the fission yeast Schizosaccharomyces pombe modulated by medium constituents.

Novel simple synthetic media for inducing sexual co-flocculation in a short time after mixing heterothallic fission-yeast (Schizosaccharomyces pombe) cells of h- and h+ were devised; The most effective of these, mannose synthetic medium (MSM), contains 0.4% mannose as a carbon source in addition to galactose, KH2PO4 (pH4.0) and 4 vitamins. The addition of galactose to the medium suppressed the asexual self-flocculation but rather promoted the sexual co-flocculation. By transferring and mixing h- and h+ cells grown in malt-extract broth plus galactose into MSM, these heterothallic strains were revealed to be sexually ready through a long period of the log to stationary phases. Furthermore, a variety of C sources and NH4Cl at various concentrations in various media were examined for their effects upon sexual co-flocculation, conjugation and sporulation; it was found that the sugar concentration strictly affected the progress of the sequence of sexual reproduction at 26 degrees C but not 30 degrees C and that sexual co-flocculation of the heterothallic strains was induced only under lower concentrations of C and N source than that for the homothallic one.

Ammonium Chloride↗