Search PubMed⌕ Search

Biomedical subjects

Y Miyata

Publications and source records attributed to Y Miyata.

At least 253 records · Page 14Linked to original sources
PubMed1987

Protein kinase C phosphorylates tau and induces its functional alterations.

We found that tau, one of the major microtubule-associated proteins, is a good substrate for protein kinase C. The phosphorylation occurred mainly on serine residues and the sites phosphorylated by protein kinase C were largely different from those phosphorylated by cAMP-dependent protein kinase as analyzed by phosphopeptide mapping. The protein kinase C-mediated phosphorylation of tau reduced its abilities to promote tubulin polymerization and to cross-link actin filaments. The reduction in its abilities was in proportion to the number of phosphates incorporated into tau.

Actins↗
PubMed1987

Postnatal transient expression of long-lasting descending inhibitory effect on spinal reflexes in the rat.

In the spinal cord isolated from neonatal rats, stimulation of the ipsilateral lateral column at the thoracic level strongly inhibited monosynaptic segmental reflex in the lumbar cord for about 60 s. The descending inhibition was not associated with any changes in the membrane potential or conductance in lumbar motoneurons when the excitatory postsynaptic potentials in response to stimulation of the dorsal root were depressed. The descending inhibition was diminished with age and could not be detected at 5 months of age. It is suggested that certain inhibitory pathways in the descending spinal tract are rearranged during postnatal development of rats.

Age Factors↗
PubMed1987

Sentence verification and event-related brain potentials.

The purpose of this study was to examine whether the decision process affected scalp recorded event-related brain potentials (ERPs). ERPs were recorded while 10 subjects evaluated the veracity of four types of Japanese sentences; true-affirmative (TA), true-negative (TN), false-affirmative (FA), and false-negative (FN). Each sentence was presented visually, one word at a time in the following order: Subject (S); object (O); and verb (V). This order of words, which is normal in Japanese grammar, allowed the ERP waveforms associated with semantic mismatch between the S and O occurring in the middle of the sentence to be separated from those elicited by the decision concerning the sentence's truth or falsity occurring at the end of the sentence. Semantic mismatch was associated with a negative component (N310) following the O-word. In addition, P3s were elicited by sentence final words. Affirmative sentences elicited larger P3s than did negative sentences, and true sentences elicited earlier P3s than did false sentences. P3s were smaller in amplitude when they followed a mismatch between the S and O words. The result suggested that by using Japanese sentences, it may be possible to examine sentence-level rather than word-level processes.

Adult↗
PubMed1987

Differences in sleep-wake habits and EEG sleep variables between active morning and evening subjects.

This article is a survey study, followed by an experimental study, examining the differences of sleep-wake habits and sleep electroencephalographic (EEG) variables between morning and evening type subjects (Ss). In the survey study, the Japanese version of the Horne and Ostberg Morningness-Eveningness Questionnaire and Life Habits Inventory (LHI) were administered to approximately 1,500 university students. The survey results showed that the two types were significantly different from each other in terms of retiring and arising time, sleep latency, mood on arising, nap, adequate amount of sleep, number of times of staying awake all night, and variability in bedtime, arising time, and sleep length. These results suggested that evening type Ss had more irregular and/or flexible sleep-wake habits than morning type Ss. In the experimental study, 10 morning and 11 evening type Ss were selected from the population included in the survey study, and polysomnograms were obtained. The results showed that only in rapid eye movement (REM) latency did morning type Ss significantly differ from evening type Ss. REM latency might be related to personality factors, particularly to neuroticism and anxiety.

Adolescent↗
PubMed1987

Cell death of axotomized motoneurones in neonatal rats, and its prevention by peripheral reinnervation.

1. Motoneurone death induced by axotomy in the rat was studied following section of the medial gastrocnemius nerve near the muscle 4 days after birth. 2. The maximum twitch tension of the medial gastrocnemius muscle achieved by motor reinnervation after section of its nerve was about 70% of that measured on the contralateral, intact side. 3. The number of motor units counted at 35-45 days of age in the animals whose medial gastrocnemius nerves had been sectioned on day 4 was 62% of that observed in normal rats. 4. The number of medial gastrocnemius motoneurones retrogradely labelled with horseradish peroxidase (HRP) 30-40 days after section of the medial gastrocnemius nerve was 77% of that labelled on the contralateral, intact side. 5. When the medial gastrocnemius nerve had been sectioned on day 4 and prevented from peripheral reinnervation, the number of medial gastrocnemius motoneurones labelled with HRP was, on the average, only 18% of that labelled on the control side. 6. Decreased number of medial gastrocnemius motoneurones labelled with HRP following prevention of peripheral reinnervation was associated with a decrease in the neurone density of the motor cell column, indicating the occurrence of motoneurone death. 7. The majority of medial gastrocnemius motoneurones axotomized 4 days after birth appear to maintain their survival for about 2 weeks without target contact. 8. The area of the compound action potential of medial gastrocnemius motor fibres once decreased after axotomy on day 4 began to recover from the 12th day after the operation if reinnervation by the cut peripheral nerve had been allowed, whereas the compound action potential continued to decrease in those axotomized motoneurones whose reinnervation had been prevented. 9. It is concluded that target dependence of motoneurone survival previously observed at embryonic stages is still present during the early post-natal period.

Action Potentials↗
PubMed1987

Thalamic projections to the second and fourth somesthetic areas in the anterior ectosylvian gyrus of the cat.

The topical organization of thalamic projections to the second and fourth somesthetic areas in the anterior ectosylvian gyrus of the cat has been studied using the technique of retrograde axonal transport of horseradish peroxidase. The projections of the posterolateral and posteromedial ventral nuclei (VPL, VPM) to the second somesthetic area (SII) are organized somatotopically. The posterior portion of SII (hindlimb area) receives fibers mainly from the dorsolateral part of VPL, the middle portion of SII (forelimb area) from the ventromedial part of VPL, and the anterior portion of SII (face area) from VPM. These topical projections are more loosely organized and less densely arranged than those to the first somesthetic area. The SII receives a few fibers from the medial geniculate nucleus, particularly its magnocellular and dorsal principal parts, and from the suprageniculate nucleus. The posterior part of SII lying near the secondary auditory area receives many fibers from the medial geniculate and suprageniculate nuclei, and only a few fibers from the lateral central and paracentral nuclei. The fourth somesthetic area (SIV), located in the dorsal bank of the anterior ectosylvian sulcus, receives fibers mainly from the dorsal principal and magnocellular parts of the medial geniculate nucleus, and from the suprageniculate nucleus. The SIV receives a fair number of fibers from VPL and VPM roughly in a somatotopical manner. The posterior portion of SIV receives fibers chiefly from the dorsolateral part of VPL, the middle portion of SIV from the ventromedial part of VPL, and the anterior portion from VPM. In addition, SIV receives a few fibers from the lateral central, paracentral, ventral lateral and ventral medial nuclei. The SIV, together with the most posterior part of SII, forms an auditory area, receiving many fibers from the medial geniculate and suprageniculate nuclei, and a few fibers from the intralaminar nuclei.

Animals↗
PubMed1986

Purified protein kinase C phosphorylates microtubule-associated protein 2.

We have investigated actions of purified protein kinase C on microtubule- and microfilament-related proteins. Among the cytoskeletal proteins examined, microtubule-associated protein 2 (MAP2) was found to serve as a good substrate. Other cytoskeletal proteins, tubulin, fodrin, cofilin, tropomyosin, and 53,000-Da protein, were very poorly phosphorylated. The amino acid residues of MAP2 that were phosphorylated by the protein kinase C were almost exclusively serine. The peptide mapping analysis indicated that protein kinase C and cAMP-dependent protein kinase phosphorylate MAP2 differently. The ability of MAP2 to interact with actin was markedly reduced by this protein kinase C-mediated phosphorylation. These data raise the possibility that phosphorylation of MAP2 by activated protein kinase C may be involved in cell-surface signal transduction.

Actins↗
PubMed1986

Binding of microtubule-associated protein 2 and tau to the intermediate filament reassembled from neurofilament 70-kDa subunit protein. Its regulation by calmodulin.

Two major brain microtubule-associated proteins (MAPs), MAP2 and tau, were found to bind to the intermediate filaments reassembled from neurofilament 70-kDa subunit protein (= 70-kDa filaments). The binding was saturable. The apparent dissociation constant (KD) for the binding of MAP2 to the 70-kDa filaments was estimated to be 4.8 X 10(-7) M, and the maximum binding reached 1 mol of MAP2/approximately 30 mol of 70-kDa protein. The apparent KD for the tau binding was 1.6 X 10(-6) M, and the maximum binding was 1 mol of tau/approximately 3 mol of 70-kDa protein. It was also found that MAP2 and tau did not compete with each other for binding to the 70-kDa filaments. Most interestingly, calmodulin, a ubiquitous Ca2+-binding protein in eukaryotic cells, was found to inhibit the binding of MAP2 and tau to the 70-kDa filaments. The inhibition by calmodulin was regulated by changes in Ca2+ concentration around 10(-6) M, and was canceled by trifluoperazine, a calmodulin inhibitor.

Animals↗
PubMed1986

Promoting effect of sodium chloride in 2-stage urinary bladder carcinogenesis in rats initiated by N-butyl-N-(4-hydroxybutyl)nitrosamine.

The promoting effect of sodium chloride (NaCl) in 2-stage urinary bladder carcinogenesis in F344 rats initiated by 2 doses of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was investigated. The incidences of PN hyperplasia were significantly higher in rats initiated with 0.01 or 0.05% BBN when they were given diet containing 10% NaCl for 32 weeks than when they were given control diet. The incidence of papilloma in rats given 0.05% BBN followed by diet containing 10% or 5% NaCl tended to be higher than that in control rats. The urine of rats given diet containing NaCl was larger in volume and had lower osmolality than that of controls. The total urinary sodium and chloride contents were also increased, whereas those of potassium and phosphorus were decreased. No calculus formation or crystalluria was observed. These data suggest that excess intake of sodium as NaCl has a weak promoting effect in 2-stage urinary bladder carcinogenesis.

Animals↗
PubMed1986

Elevated levels of serum pancreatic secretory trypsin inhibitor (PSTI) in patients with malabsorption syndrome.

Serum pancreatic secretory trypsin inhibitor (PSTI) was measured by radioimmunoassay in 5 patients with malabsorption syndrome. The serum level of PSTI was elevated to 123.8 +/- 25.8 ng/ml (Mean +/- SE) in patients with malabsorption syndrome, which was significantly higher than the 16.6 +/- 0.7 ng/ml level seen in 116 healthy control subjects. Serum PSTI levels in 5 patients with malabsorption syndrome showed inverse correlations with serum levels of cholesterol, cholinesterase and amylase, and not with serum levels of vitamin E, carotene, apoprotein A-IV, albumin, nor with immunoreactive elastase 1, respectively. These results suggest that elevated levels of serum PSTI represent a state of malnutrition due to impaired intestinal absorption.

Adult↗
PubMed1986

Alterations in plasma levels of apolipoprotein A-IV in various clinical entities.

The serum levels of apolipoprotein A-IV (apo A-IV) were measured by rocket immunoelectrophoresis in disease-free humans, at fasting and after oral and intravenous fat administration. The studies were extended to patients with chronic pancreatitis, malabsorption syndrome, to postoperative patients on total parenteral nutrition and to patients with liver diseases, cholestasis, diabetes mellitus and chronic renal failure. Oral fat ingestion resulted in an increase of apo A-IV levels which remained elevated even when the postprandial hypertriglyceridemia had disappeared. A transient increase in apo A-IV levels was observed after intravenous fat infusion but the level declined simultaneously with decreases in triglyceride levels. Levels of serum apo A-IV were decreased under conditions where decreased fat intake or malabsorption of nutrients might have been present, such as in patients with chronic pancreatitis, malabsorption syndrome, acute hepatitis in the early stage, obstructive jaundice and in postoperative patients on total parenteral nutrition. On the other hand, the apo A-IV levels were high in patients with chronic renal failure and in those with diabetes mellitus and proteinuria.

Adult↗