Search PubMed⌕ Search

Biomedical subjects

S Miyake

Publications and source records attributed to S Miyake.

At least 217 records · Page 12Linked to original sources
PubMed1992

[Prevalence rate of severely mentally and physically handicapped children in school age in Yokohama].

Prevalence rate and pattern of disabilities were studied in severely mentally and physically handicapped children in school age in Yokohama. We visited institutions and schools for retarded children in Yokohama and its neighborhood or made contact with them by telephone. The study disclosed a total of 192 children on May 1, 1988. Prevalence rate was 0.51 per 1,000. Patterns of disabilities were: 1) most of the children (94.8%) lived with their families. 2) eighty-eight percent of the children attended school for retarded children. 3) about twenty percent of the children who attended school needed tube feeding.

Child↗
PubMed1991

Pentoxifylline prevents tumor necrosis factor-induced suppression of endothelial cell surface thrombomodulin.

Thrombomodulin (TM) expression has been reported to be down-regulated by cytokines (endotoxin, interleukin-1, and tumor necrosis factor). We report, in the present study, up-regulation of surface TM antigen of human umbilical vein endothelial cells (HUVECs) by pentoxifylline (PTX) which is one of the agents that can increase intracellular cyclic AMP in HUVECs at therapeutic concentrations. Surface TM antigen was measured by an enzyme immunoassay. PTX increased surface TM antigen and intracellular cAMP in HUVECs in a dose dependent manner. Upregulation of TM by PTX was due to de novo synthesis of TM protein resulting from increased TM mRNA levels. PTX counterbalanced the TNF-induced suppression of TM expression. These results suggest that protein kinase A may be involved in cellular regulatory mechanism for TM expression and PTX may protect partially against TNF-induced endothelial cell injury and restore anticoagulant state of endothelium.

Antibodies↗
PubMed1991

Mapping of four ras superfamily genes by physical and genetic means in Schizosaccharomyces pombe.

Four ras superfamily genes, namely ypt1, ypt2, ypt3 and ryh1, have been located on the S. pombe linkage map. This was achieved by constructing strains carrying a new NotI cutting site and the S. cerevisiae LEU2 gene integrated next to the respective gene. The physical location of these genes of the chromosomes was then determined by NotI restriction analysis of the DNA prepared from each strain. Fine genetic mapping was carried out by conventional tetrad analysis using the integrated LEU2 gene as a marker. The results indicated that ypt1 is tightly linked to top1 on the right arm of chromosome II; that ypt2 is 2.5 cM apart from ura2 on the right arm of chromosome I; that ypt3 is tightly linked to arg3 on the left arm of chromosome I; and that rhy1 is located approximately 20 cM from ade3 on the left arm of chromosome I.

Chromosome Mapping↗
PubMed1991

Production of infectious particles from defective human immunodeficiency virus type 1 (HIV-1)-producing cell clones by superinfection with infectious HIV-1.

A total of 81 cell clones persistently infected with the LAV-1 or HTLV-IIIB strain of human immunodeficiency virus type 1 (HIV-1) was isolated from cells which were obtained by serial passage of some proliferating MT-4 cells after a drastic cytolysis of most cells by HIV-1-infection. These cell clones were classified into 8 types (I to VIII) in terms of the expression of HIV-1 antigens, syncytium formation capacity, and reverse transcriptase activity and infectivity of virus particles in the culture fluid. Type I cell clones were producers of infectious HIV-1 particles, while types II to VIII cell clones did not produce infectious HIV-1 or were producers of uninfectious defective HIV-1 particles. Immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis (PAGE) showed that the gag precursor protein in L-2 cell clone (type IV) was not cleaved to mature gag proteins, while the env precursor protein on L-3 cell clone (type III) was not cleaved to mature env protein. H-7 cell clone (type VIII) did not express any HIV-1 antigen. All these cell clones after the superinfection with infectious HIV-1 synthesized intact gag and env proteins, which were, at least in part, related to the HIV-1 genome persistently present in the cell clones before the superinfection, resulting in production of infectious HIV-1. For example, it was found that L-2 cell clone contained a single copy of the LAV-1 genome per haploid cell and produced doughnut-shaped particles. On the other hand, the cell clone isolated from the L-2 cell clone superinfected with infectious HTLV-IIIB contained the integrated HTLV-IIIB genome in addition to the LAV-1 genome present before the superinfection, and produced intact HIV-1 particles in addition to doughnut-shaped particles from a single cell. These results indicate that complementation and/or genetic recombination events in the superinfected cells may account for the production of infectious intact HIV-1 virions.

Animals↗
PubMed1991

Electrophysiological effects of endothelin-1 on canine myocardial cells.

Endothelin-1 (ET-1) has been shown to induce severe ventricular arrhythmias associated with myocardial ischemia. However, ET-1 may have a direct arrhythmogenic action that is not related to myocardial ischemia. To examine this possibility, we studied the electrophysiological effects of ET-1 on cardiac tissues. The right bundle branch, false tendon, ventricular muscle, and atrial muscle were isolated from the dog, and transmembrane potentials were recorded by the conventional microelectrode technique. ET-1 prolonged the action potential duration (APD) in all of the tissues tested except in the atrial muscle, where the APD was shortened. Bay K 8644, a calcium channel agonist, prolonged the APD in all cardiac tissues. Spontaneous firing of the right bundle branch was suppressed by ET-1 but not Bay K 8644. The prolongation of the APD by ET-1 was far more marked in the right bundle branch than in other tissues, and it was followed by the development of early after depolarizations (EADs) only in the right bundle branch. The EADs induced by ET-1 or Bay K 8644 were abolished by nicardipine. These data suggest that L-type calcium current is involved in the genesis of EADs by ET-1, although other ionic mechanisms can not be ruled out. Since EADs underlie some types of arrhythmias, arrhythmias caused by ET-1 are at least partly attributable to the direct actions of the agent on myocardial cells.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Identification of a GTPase-activating protein homolog in Schizosaccharomyces pombe.

Loss of function of the Schizosaccharomyces pombe gap1 gene results in the same phenotypes as those caused by an activated ras1 mutation, i.e., hypersensitivity to the mating factor and inability to perform efficient mating. Sequence analysis of gap1 indicates that it encodes a homolog of the mammalian Ras GTPase-activating protein (GAP). The predicted gap1 gene product has 766 amino acids with relatively short N- and C-terminal regions flanking the conserved core sequence of GAP. Genetic analysis suggests that S. pombe Gap1 functions primarily as a negative regulator of Ras1, like S. cerevisiae GAP homologs encoded by IRA1 and IRA2, but is unlikely to be a downstream effector of the Ras protein, a role proposed for mammalian GAP. Thus, Gap1 and Ste6, a putative GDP-GTP-exchanging protein for Ras1 previously identified, appear to play antagonistic roles in the Ras-GTPase cycle in S. pombe. Furthermore, we suggest that this Ras-GTPase cycle involves the ra12 gene product, another positive regulator of Ras1 whose homologs have not been identified in other organisms, which could function either as a second GDP-GTP-exchanging protein or as a factor that negatively regulates Gap1 activity.

Amino Acid Sequence↗
PubMed1991

Power spectral analysis of blood pressure variability in traumatic quadriplegic humans.

A study was performed on seven traumatic neurologically complete quadriplegic (QP) males and seven age-matched healthy males (control) while they were at rest in the supine position in a climatic chamber (temperature 30 degrees C, relative humidity 60%). Arterial blood pressure waveforms were measured by a continuous noninvasive blood pressure-monitoring system based on arterial tonometry. Furthermore, the spontaneous beat-to-beat systolic blood pressure (SBP) variabilities of subjects were investigated by means of autoregressive power spectral analysis. As shown by earlier studies with an invasive (intra-arterial) blood pressure-monitoring system, in the control group there were two major spectral components: a high-frequency (HF) component [center frequency 0.27 +/- 0.02 (SE) Hz eq, power 0.9 +/- 0.2 mmHg2] and a low-frequency (LF) component (0.10 +/- 0.01 Hz eq, 5.2 +/- 1.4 mmHg2). On the contrary, in the QP group only the HF component was observed (0.28 +/- 0.03 Hz eq, 3.2 +/- 1.4 mmHg2). The results suggest that 1) in the QP subject the disappearance of the LF component in the SBP variability (i.e., the Mayer waves in humans) is presumably caused by the interruption of the spinal pathways linking supraspinal cardiovascular centers with the peripheral sympathetic outflow and 2) the cervical spinal sympathetic pathways may be instrumental in the genesis of the Mayer waves in humans.

Adult↗
PubMed1991

Antiarrhythmic and cardiovascular profiles of the fused indole compound (3aR,12R,12aR,12bS)-12-amino-2,3,3a,4,11,12,12a,12b-octahydro-10-hydrox yisoquino [2,1,8-lma]carbazol-5(1H)-one hydrochloride 1.5 hydrate.

Antiarrhythmic and cardiovascular profiles of a fused indole compound, (3aR,12R,12aR,12bS)-12-amino-2,3,3a,4,11,12,12a,12b -octahydro- 10-hydroxyisoquino [2,1,8-lma]carbazol-5(1H)-one hydrochloride 1.5 hydrate (RS-2135, CAS 133775-36-7), were investigated in anesthetized dogs. Class I antiarrhythmic agents such as disopyramide, lidocaine, mexiletine and flecainide were used as reference compounds. RS-2135 exerted more potent antiarrhythmic activity than reference compounds against ouabain-induced arrhythmias in dogs. The onset of action was slow, but the duration of action was longer than with the other compounds tested. The agent suppressed the conduction in the atrium, A-V node and ventricle more markedly than the reference compounds. RS-2135, however, did not change blood pressure and heart rate at a dose 5 times the dose for antiarrhythmic activity and decreased cardiac contractility to a lesser extent than the reference compounds.

Animals↗
PubMed1991

[The problems of valproate therapy in severely handicapped children--valproate induced hyperammonemia and hypocarnitinemia].

Blood ammonia and serum free carnitine were measured in 49 severely handicapped epileptic patients treated with or without valproate. DL- or L-carnitine were administered to patients treated with valproate, and the effects of carnitine supplementation were evaluated. Furthermore we analyzed the relationship between serum free carnitine and nutrition. In patients treated with valproate, blood ammonia statistically increased, and serum free carnitine concentration statistically decreased. Free carnitine was low in tube-fed patients, as compared with that in oral-fed patients. Carnitine therapy was successful in improvement of hyperammonemia and hypocarnitinemia. It is concluded that hypocarnitinemia was caused not only by valproate therapy, but also by tube-feeding. Carnitine supplementation therapy is important to both hyperammonemia and hypocarnitinemia. But the long term effect of carnitine therapy remains to be studied further.

Adolescent↗
PubMed1991

[Mortality patterns of children with epilepsies in a children's medical center].

Two hundred and thirty-seven children have died who were seen in the Division of Neurology, Kanagawa Children's Medical Center from 1975 to 1989. They corresponded to about 11% of the total death in the hospital. A total of 128 cases of 237 deaths (54.0%) were suffering from epilepsies, most of whom were also complicated with other CNS disorders. The causes of death were pneumonia, respiratory failure and suffocation in 60%, whereas status epilepticus or convulsions only in 14%. About 40% of victims died at home or in an emergency room without effective resuscitation. Mortality was considered high in infantile spasms (16 out of 146, 11%) and in severe myoclonic epilepsy in infancy (4 out of 8, 50%). It was note worthy that 3 cases of severe myoclonic epilepsy in infancy died of status epilepticus and 2 died at home. Sixteen cases whose chief problems were partial epilepsies and severe myoclonic epilepsy in infancy, died of status epilepticus in 10 cases, convulsions after tonsillectomy, etc. Causes of death of these 16 cases were related to convulsions except in two cases whose causes were pneumonia in one and unknown in the other. About a half of them (7 cases) died at home. Adequate managements appeared necessary to prevent accidental deaths of children with epilepsies.

Cause of Death↗
PubMed1991

[Four cases of Cockayne syndrome].

The evaluation of four patients with Cockayne syndrome (CS) by computed tomography (CT) and magnetic resonance imaging (MRI) is reported. All patients had characteristic clinical manifestations of CS. In a special respect, we found hyperopia in two patients and previous habitual abortions in two maternal histories. Extrapyramidal signs were seen in one patient. Three patients are type 1 CS (case 1, 3, 4) and one patient (case 2) is type 2 CS (congenital form). The cranial CT in two patients (case 1, 2) revealed prominent calcifications in basal ganglia, dentate nucleus and hemispheric white matter. While CT showed vagal calcifications in basal ganglia in other two patients (case 3, 4), T2-weighted MRI revealed obvious low intensity area in putamen and caudate nucleus, and high intensity area in the white matter. Sagittal section revealed atrophic changes of cerebellar vermis and brain stem. Thus it seems that MRI may be useful diagnostic adjunct in CS patients.

Brain↗
PubMed1991

[The investigation of the stereoacuity in infants measured by the TV-Random Dot Stereo Test].

Evaluation of the level of stereoacuity in infants as early as possible is very important to detecting abnormalities and preventing further disturbance in visual functions. We developed a new instrument which permits the quantitative measurement of stereoacuity in infants. A total of 217 ophthalmologically normal infants were tested and stereoacuity was detected in 141 infants. Stereopsis is likely to arise at 3-4 months of age and develops as the infant grows. It can develop rapidly after the age of one year. The rate of detection was 48% in infants below 6 months old, and 65% as an overall mean among all age groups under 3 years of age. This new instrument, the TV-Random Dot Stereo Test, is very important to quantitatively measure stereoacuity of infants aged under 3 years, more simply and with greater reliability than other kinds of stereo tests for infants.

Age Factors↗
PubMed1991

[Insertion anomalies of the horizontal muscles and dysfunctions of the oblique muscles in the A-V patterns].

Insertion anomalies of the horizontal rectus muscles and dysfunctions of the oblique muscles were studied in 141 cases with A-V patterns of 824 patients with horizontal strabisums. The frequency of insertion anomaly among all cases of A-V pattern studied was 49.6%, there were more V pattern insertion anomalies than in those of A pattern, but the ratio of insertion anomalies in each type of A-V pattern was more in the A pattern than in the V pattern. In the oblique muscles, overaction of the inferior oblique muscle in the V pattern and of the superior oblique muscle in the A pattern were frequently encountered and insufficient action of the oblique muscles occurred more frequently in cases A-V esotropia than in cases of exotropia. In cases of combination of insertion anomaly of the horizontal rectus muscles with dysfunction of the oblique muscles, insertion anomaly was involved in 91.3% of cases of overaction of the superior oblique muscles, but only in 37.4% of cases of overaction of the inferior oblique muscles. The combination of insertion anomalies with dysfunction of the oblique muscles suggests a possible existence of simulated dysfunction of the oblique muscles in some cases of dysfunction of the oblique muscles diagnosed preoperatively. At the choice of a procedure in surgical correction, a confirmation of insertions of the horizontal muscles during operations is needed, and for this purpose the perilimbal incision is more appropriate than the fornix incision.

Eye Movements↗
PubMed1990

Evidence for direct arrhythmogenic action of endothelin.

We studied electrophysiological effects of endothelin on canine cardiac tissues. Endothelin prolonged action potential duration and decreased spontaneous firing rate of the right bundle branch cells. At a concentration of 2 x 10(-7)M the plateau phase of action potentials was flattened, followed by the abrupt occurrence of early afterdepolarizations (EADs). ET, at a concentration as low as 2 x 10(-9)M, was capable of inducing EADs although their incidence was low. The EADs were initiated from the membrane potential less negative than -30mV and were suppressed by nicardipine, suggesting the involvement of dihydropyridine-sensitive Ca2+ channels in the induction of EADs. Because EADs are considered to underlie certain types of arrhythmias endothelin per se may have arrhythmogenic action.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

Identification of ras-related, YPT family genes in Schizosaccharomyces pombe.

Screening for genes homologous to ras in Schizosaccharomyces pombe resulted in the isolation of a homolog of Saccharomyces cerevisiae YPT1. This S. pombe gene, named ypt3, has a coding capacity of 214 amino acids interrupted by two introns, and is essential for cell growth. Two more YPT1 homologs were isolated from S. pombe using a part of the ypt3 gene as the probe. One of them, named ypt1, is highly homologous to S. cerevisiae YPT1 and mouse ypt1 and is essential for cell growth. This gene has four introns and encodes 203 amino acids. Its cDNA placed downstream of the S. cerevisiae GAL7 promoter could complement S. cerevisiae ypt1-, indicating that Sp ypt1 and Sc YPT1 are functionally homologous. The other isolate, named ryh1, and a fourth homolog, ypt2, have been characterized by Gallwitz and co-workers. The ypt1, ypt2 and ypt3 genes, but not ryh1, constitute a family, their products having double cysteine as their C terminus and serine in place of a glycine residue highly conserved in ras proteins (mammalian Gly-12 or S. pombe Gly-17). The physiological roles of these genes appear to be distinct because each of them is indispensable for cell growth.

Amino Acid Sequence↗