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Biomedical subjects

C Miyazaki

Publications and source records attributed to C Miyazaki.

At least 19 recordsLinked to original sources
PubMed2001

Engineering of the H2O2-binding pocket region of a recombinant manganese peroxidase to be resistant to H2O2.

The manganese peroxidase produced by Phanerochaete chrysosporium, which catalyzes the oxidation of Mn(2+) to Mn(3+), is easily inactivated by the hydrogen peroxide (H2O2) presented in the reaction. We attempted to increase H2O2 resistance by the conformational stabilization around the H2O2-binding pocket. Based on its structural model, engineering of oxidizable Met273 located near the pocket to a non-oxidizable Leu showed a great improvement. Furthermore, after treatment at 1 mM H2O2 where the wild-type is completely inactivated, full activity can be retained by engineering the Asn81, which might have conformational changes due to the environment of the pocket, to a non-bulky and non-oxidizable Ser.

Binding Sites↗
PubMed2001

Differences between the tolerance characteristics of two anticonvulsant benzodiazepines in the amygdaloid-kindled rat.

The characteristics of the development of tolerance to the anticonvulsant effects of chronic treatment by dipotassium clorazepate and diazepam using amygdaloid-kindled rats were investigated. Dipotassium clorazepate (5 mg/kg) or diazepam (5 mg/kg) were intraperitoneally administered for 10 consecutive days. Tolerance to the anticonvulsant effect of dipotassium clorazepate developed in seizure stage on day 6, after-discharge duration on day 7 and seizure latency on day 4. In contrast, tolerance to the effects of diazepam developed more rapidly in seizure stage on day 4, after-discharge duration on day 4 and seizure latency on day 3. Thus tolerance to the anticonvulsive effect of dipotassium clorazepate developed relatively slower than that to diazepam. All rats had stage 5 convulsions 24 hr after cessation of the administration of dipotassium clorazepate and diazepam. Concomitant determinations of plasma concentrations of the main metabolite of dipotassium clorazepate and diazepam, desmethyldiazepam, showed no statistical difference during treatment, suggesting that the developed tolerance was not metabolic but functional.

Amygdala↗
PubMed2001

Assessment of coronary flow velocity with transthoracic Doppler echocardiography during dobutamine stress echocardiography.

OBJECTIVES: The purpose of this study was to evaluate the feasibility of measuring coronary flow velocity (CFV) by transthoracic Doppler echocardiography (TTDE) in the left anterior descending coronary artery (LAD) during contrast-enhanced dobutamine stress echocardiography (DSE). We also assessed the value of TTDE for detecting stress-induced myocardial ischemia in the LAD territory. BACKGROUND: Noninvasive assessment of both CFV and wall motion during DSE would enhance the diagnostic accuracy of DSE. METHODS: One hundred forty-four consecutive patients underwent CFV recording in the distal LAD by TTDE during contrast-enhanced DSE. Regional wall motion score index (WMSI) in the LAD territory and CFV ratio at peak stress (CFV ratio peak), defined as a ratio of CFV at peak stress to basal CFV, were obtained. RESULTS: Coronary flow velocity was successfully recorded in 129 patients (90%) at baseline and during dobutamine infusion. Mean value of CFV ratio peak was 2.39 +/- 0.83 (range: 0.84 to 4.40). There was good correlation between WMSI at peak stress and CFV ratio peak (r = 0.62, p < 0.001). Coronary flow velocity ratio peak was significantly lower in patients who developed stress-induced wall motion abnormality (WMA) in the LAD territory than it was in those patients without WMA (1.51 +/- 0.51 vs. 2.76 +/- 0.65, p < 0.001). A CFV ratio peak <2.1 had a sensitivity of 92% and a specificity of 86% for detecting the presence of stress-induced WMA. CONCLUSIONS: Assessment of CFV in the distal LAD during DSE is feasible in the majority of cases and provides a CFV ratio for detecting stress-induced myocardial ischemia in the LAD territory.

Adult↗
PubMed2001

The Purple leaf (Pl) locus of rice: the Pl(w) allele has a complex organization and includes two genes encoding basic helix-loop-helix proteins involved in anthocyanin biosynthesis.

The Purple leaf (Pl) locus of rice (Oryza sativa L.) affects regulation of anthocyanin biosynthesis in various plant tissues. The tissue-specific patterns of anthocyanin pigmentation, together with the syntenic relationship, indicate that the rice Pl locus may play a role in the anthocyanin pathway similar to the maize R/B loci. We isolated two cDNAs showing significant identity to the basic helix-loop-helix (bHLH) proteins found in the maize R gene family. OSB1 appeared to be allelic to the previously isolated R homologue, Ra1, but showed a striking difference at the C-terminus because of a 2-bp deletion. Characterization of the corresponding genomic region revealed that the sequence identical to a 5'-portion of OSB2 existed approximately 10-kb downstream of the OSB1 coding region. OSB2 lacks a conserved C-terminal domain. Restriction fragment length polymorphism analyses using an F(2) population indicate that both genes co-segregate with the purple leaf phenotype. A transient complementation assay showed that the anthocyanin pathway is inducible by OSB1 or OSB2. These results suggest that the Pl(w) allele may be complex and composed of at least two genes encoding bHLH proteins.

Alleles↗
PubMed2001

[A case of lung cancer in which FDG-PET was useful for preoperative diagnosis].

The patient was 48-year-old woman. The patient was referred to our hospital due to detection of an abnormal shadow on a chest X-ray image during a health checkup. The results of a CT scan morphologically suggested a benign tumor, but a diagnosis could not be made even after bronchoscopic cytology. FDG-PET revealed accumulation at the tumor site suggestive of malignancy, and an operation was performed. Prompt pathological examination showed that the tumor was adenocarcinoma, and right lower lobectomy and lymphnode dissection were performed. FDG-PET is thought to be useful for diagnosis in cases of lung tumor in which a preoperative diagnosis can not be established.

Adenocarcinoma↗
PubMed2000

Unusual occipital condyle fracture with multiple nerve palsies and Wallenberg syndrome.

A 52-year-old male presented with an extremely rare fracture of the occipital condyle involving the jugular foramen with marked medial rostrad displacement of the fragments. He had ipsilateral VII through XII nerves palsies and Wallenberg syndrome. Conservative treatment did not improve the cranial nerve palsies. A high-resolution CT-scan is essential to visualize these fractures.

Accidents, Occupational↗
PubMed2000

Characteristics of epilepsy in severely mentally retarded individuals.

In order to clarify the characteristics of epilepsy in patients with severe mentally retarded (SMR) subjects, we analyzed 52 SMR subjects with epilepsy from the institute for SMR subjects at Kikuchi National Hospital, Kumamoto, Japan. A total of 61.5% patients had uncontrolled seizures which were resistant to treatment. The most common combinations of seizure types in those not responding to conventional anticonvulsants were generalized tonic-clonic seizures (GTCS) with tonic seizure and GTCS with atypical absence. Their clinical features were characterized by spastic paralysis associated with a slower background electroencephalogram and abnormal computed tomography scans of the head, suggesting the involvement of cortical damage. These findings suggest that a large proportion of epilepsy in SMR subjects does not respond to treatment and that the severity of organic brain damage may therefore affect the natural course of epilepsy in such patients.

Adolescent↗
PubMed1999

Effect of dipotassium clorazepate on amygdaloid-kindling and comparison between amygdaloid- and hippocampal-kindled seizures in rats.

We examined the effect of dipotassium clorazepate (7-chloro-1, 3-dihydro-2-oxo-5-phenyl-1H-1, 4-benzodiazepine-3-carboxylate potassium hydroxide), an antianxiety drug, on amygdaloid kindling and compared its effects for 7 successive days on amygdaloid- versus hippocampal-kindled seizures, using the rat kindling model of epilepsy. Dipotassium clorazepate at 5 mg/kg significantly delayed amygdaloid kindling. The contralateral cortical after-discharge duration in the dipotassium clorazepate-treated group was significantly shorter than the after-discharge duration in the amygdala in the first seven stimulations, whereas it was significantly shorter only in the first three stimulations in the control group, indicating that dipotassium clorazepate suppressed the spread of seizure activity from focus to contralateral cortex. Dipotassium clorazepate suppressed amygdaloid-kindled seizures at 2 and 5 mg/kg, while 1 mg/kg or more suppressed hippocampal-kindled seizures. Thus, differences in effective dosages in both amygdaloid- and hippocampal-kindled seizures may suggest a difference in the neuronal mechanisms involved in this kindling.

Amygdala↗
PubMed1999

Host immune responses to ribosome, ribosomal proteins, and RNA from Mycobacterium bovis bacille de Calmette-Gúerin.

The ribosomes from BCG strongly induced delayed type hypersensitivity (DTH) skin reactions in guinea pigs immunized with live BCG or heat killed Mycobacterium tuberculosis H37Rv, and also induced lymphocyte proliferative response in mice immunized with ribosomes. In contrast, neither ribosomal proteins nor RNA alone induced both DTH skin reactions and lymphocyte proliferative responses. Particle form consisted of ribosomal proteins and RNAs might be absolutely required for the activation of immune responses.

Animals↗
PubMed1999

Isolation of a protease-deficient mutant of Bacillus brevis and efficient secretion of a fungal protein disulfide isomerase by the mutant.

The efficient production of a thermostable protein disulfide isomerase (PDI) was successfully achieved using the newly isolated protease-deficient mutant, Bacillus brevis 31-OK. Extracellular protease (exoprotease) activity was about a quarter of that in the parent, and the mutant was deficient in at least one of the major exoproteases. The cDNA encoding the fungal PDI was inserted downstream of the signal peptide-encoding region in an expression-secretion vector for B. brevis. Efficient production of PDI was feasible using B. brevis 31-OK as a host and modified signal sequences composed of three leucine residues inserted in the hydrophobic region of the MWP (middle wall protein) signal sequence. The maximal secretion of PDI into the culture medium was 1.1 g/l, which is about twice that by the parent strain and fifty times greater than the amount of rat and murine PDIs produced by Escherichia coli. The enzymatic properties such as the specific activity and thermal stability of the recombinant PDI are similar to those of natural PDI derived from Humicola insolens mycelia. B. brevis 31-OK was able to maintain its exoprotease activity at a low level throughout the cultivation and is considered to be useful host for production of a protease-sensitive protein and for increase of protein productivity due to stable accumulation.

Journal Article↗
PubMed1999

Changes in the specificity of antibodies by site-specific mutagenesis followed by random mutagenesis.

The specificity for 11-deoxycortisol (11-DOC) of a monoclonal antibody (mAb), designated SCET, was changed to specificity for cortisol (CS) by site-specific mutagenesis followed by random mutagenesis. The Fab form of SCET was expressed on the surface of a phage. During the first step, mutations were introduced at 14 amino acid positions in three complementarity-determining regions (CDRs) of the VH domain that seemed likely to form the steroid-binding pocket. A clone, DcC16, was isolated from the resultant library with multiple mutations and this clone was shown to have CS-binding activity but also to retain high 11-DOC-binding activity. During the second step, mutations were introduced randomly into the entire VH-coding region of the DcC16 clone by an error-prone polymerase chain reaction, and CS-specific mutant antibodies were selected in the presence of 11-DOC as a competitor. Three representative clones were analyzed with the BIAcore instrument, and each revealed a large increase in the binding constant for CS and a decrease in that for 11-DOC. Structural models, constructed by computer simulation, indicated the probable molecular basis for these changes in specificity.

Amino Acid Sequence↗
PubMed1998

Incidence of congenital rubella syndrome and influence of the rubella vaccination program for schoolgirls in Japan, 1981-1989.

In 1984, the authors first conducted a nationwide survey of deaf children with a history of maternal rubella (HMR) in special schools for the deaf in Japan. The survey showed that the incidence of congenital rubella syndrome in the Japanese mainlands was similar to those in the United States and Europe. In 1993, a second nationwide survey by the authors evaluated the efficacy of the vaccination program for schoolgirls begun in 1977. This second survey yielded 272 deaf children with HMR born between 1981 and 1989. Per 100,000 annual livebirths, the incidence rates were 1.56-9.95 in the epidemic years 1981-1982 and 1987-1988 and 0.20-0.72 in the interepidemic years. During the 1987-1988 epidemic, the incidence rates per 100,000 livebirths were 1.52 among mothers eligible for the vaccination program and 5.52-7.44 among mothers not eligible, and the difference was significant. However, only 21.7% of the women who delivered children during the 1987-1988 rubella epidemic were eligible for the vaccination program, and because the majority of deaf children with HMR were born to mothers not eligible, a decrease in the birth rate of deaf children with HMR was not observed. These data suggested the need to introduce a new vaccine program to suppress rubella epidemics.

Adolescent↗
PubMed1998

Anticonvulsant effects of dipotassium clorazepate on hippocampal kindled seizures in rats.

We examined the anticonvulsant properties of dipotassium clorazepate (DC) against hippocampal kindled seizures in rats. Adult male Wistar rats were subjected to kindling 1 week after the implantation of electrodes. After five stage 5 seizures were induced, the generalized convulsion triggering threshold (GST) was determined. Dipotassium clorazepate was administered intraperitoneally in rats that showed two stable stage 5 seizures induced at the GST current intensity. Dipotassium clorazepate at doses of 1 mg/kg or more produced an anticonvulsant effect, but did not readily suppress limbic seizures. Dipotassium clorazepate did not completely suppress after-discharges (AD) even at the highest dose, which was 5 mg/kg. Moreover, raised stimulus intensity failed to affect its efficacy as an anticonvulsant. The results of the present study suggest that DC has a modest anticonvulsant potency. It is reasonable to assume that its anticonvulsant efficacy is primarily due to attenuation of AD propagation rather than the raising of the seizure triggering threshold at the kindling focus.

Animals↗
PubMed1997

Intrapulmonary Mycobacterium avium infection as the first manifestation of chronic granulomatous disease.

A 10-month-old Japanese male infant, with no history of being prone to infections, contracted an intrapulmonary mycobacterial infection. After 2 months of intermittent fever, radiological examinations revealed mass lesions in the lung and mediastinum. Biopsy specimens showed granulomas with caseous necrosis, from which Mycobacterium avium was isolated. There was no history of mycobacteriosis or immunodeficiency diseases among his relatives. Analyses of the O2- release and expression of NADPH oxidase components verified that he suffered from gp91-phox- chronic granulomatous disease (CGD), and that his mother was a carrier of the disease. This is a rare clinical presentation for the onset of CGD, suggesting that the invasive mycobacteriosis might result from defective intracellular killing of CGD-phagocytes.

Granulomatous Disease, Chronic↗
PubMed1997

Twenty-three-year follow-up study of rubella antibodies after immunization in a closed population, and serological response to revaccination.

Twenty-six institutionalized children immunized with a Japanese rubella vaccine, Matsuba strain, have been observed for 23 years and the persistence of vaccine-induced rubella immunity documented. All vaccinees were shown to have seroconverted to rubella virus in a haemagglutination inhibition (HI) test, and the geometric mean titre (GMT) of rubella HI antibody rose to 2 5-8 months after vaccination (Ueda et al., Acta Paediatrica Japonica, Overseas Edition 1978, 20, 8-14). The GMT then declined gradually to 2 23 years after inoculation, except in four cases (15.4%) which had reverted to negative. However, three of the four maintained a rubella HI antibody titre of 1:4. Twelve of the 26 vaccinees were revaccinated 24 years after primary vaccination, and all ten cases having initial titres of < or = 1:16 demonstrated secondary responses. Rubella immunity induced by vaccination had persisted, so routine booster immunization did not seem necessary. However, a second immunization programme should be considered to achieve high antibody-positive rates and to protect against primary vaccine failure.

Adolescent↗