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Y Wakayama

Publications and source records attributed to Y Wakayama.

At least 19 recordsLinked to original sources
PubMed2001

Muscle plasma membrane changes in dystrophin gene exon 52 knockout mouse.

Changes in muscle plasma membranes in mice lacking exon 52 of the dystrophin gene (mdx52 mouse) were studied using the freeze-fracture technique. The extensor digitorum longus (EDL) muscle plasma membrane of the mdx52 mouse at 8 weeks of age showed significantly increased caveola density (p < 0.05 by two-tailed t-test) and significantly decreased densities of intramembranous particles (IMPs), orthogonal arrays (OAs) and orthogonal array subunit particles (OASPs) (p < 0.05 by two-tailed t-test, p < 0.01 by Wilcoxon rank-sum test, p < 0.05 by two-tailed t-test, respectively) on the protoplasmic face when compared with those of control EDL muscles. These changes are more similar to those seen in DMD than those in the mdx mouse at the same age as reported previously. Thus, the gene abnormality in the different exon of the mouse dystrophin gene seems to induce somewhat different changes in the muscle plasma membrane.

Animals↗
PubMed2001

Stretch and quick release of rat cardiac trabeculae accelerates Ca2+ waves and triggered propagated contractions.

Rapid shortening of active cardiac muscle [quick release (QR)] dissociates Ca2+ from myofilaments. We studied, using muscle stretches and QR, whether Ca2+ dissociation affects triggered propagated contractions (TPCs) and Ca2+ waves. The intracellular Ca2+ concentration was measured by a SIT camera in right ventricular trabeculae dissected from rat hearts loaded with fura 2 salt, force was measured by a silicon strain gauge, and sarcomere length was measured by laser diffraction while a servomotor controlled muscle length. TPCs (n = 27) were induced at 28 degrees C by stimulus trains (7.5 s at 2.65 +/- 0.13 Hz) at an extracellular Ca2+ concentration ([Ca2+]o) = 2.0 mM or with 10 microM Gd3+ at [Ca2+]o = 5.2 +/- 0.73 mM. QR during twitch relaxation after a 10% stretch for 100-200 ms reduced both the time between the last stimulus and the peak TPC (PeakTPC) and the time between the last stimulus and peak Ca2+ wave (PeakCW) and increased PeakTPC and PeakCW (n = 13) as well as the propagation velocity (Vprop; n = 8). Active force during stretch also increased Vprop (r = 0.84, n = 12, P < 0.01), but Gd3+ had no effect (n = 5). These results suggest that Ca2+ dissociation by QR during relaxation accelerates the initiation and propagation of Ca2+ waves.

Actin Cytoskeleton↗
PubMed2001

Effect of transient stretch on intracellular Ca2+ during triggered propagated contractions in intact trabeculae.

Transient stretch of cardiac muscle during a twitch contraction may dissociate Ca2+ from myofilaments into the cytosol at the moment of quick release of the muscle. We studied the effect of stretch and quick release of trabeculae on changes in intracellular Ca2+ ([Ca2+]i) during triggered propagated contractions (TPCs). Trabeculae were dissected from the right ventricle of 9 rat hearts. [Ca2+]i was measured using electrophoretically injected fura-2. Force was measured using a silicon strain gauge and sarcomere length was measured using laser diffraction techniques. Reproducible TPCs (n = 13) were induced by trains of electrical stimuli (378 +/- 19 ms interval) for 7.5 s at [Ca2+]o of 2.0 mM (27.9 +/- 0.2 degrees C). The latency of the TPC force and the underlying increase in [Ca2+]i was calculated from the time (TimeF) between the last stimulus and the peak of TPC force (PeakF), or the time (TimeCa) between the last stimulus and the peak of the increase in [Ca2+]i during the TPCs (PeakCa). As a result of a 10% increase in muscle length for 150-200 ms during the last stimulated twitches, TimeF and TimeCa decreased and PeakF and PeakCa increased significantly (n = 13). In addition, transient stretch sometimes induced a twitch contraction subsequent to the accelerated TPC and its underlying increase in [Ca2+]i. These results suggest that Ca2+ binding and dissociation from the myofilaments by the stretch and quick release of muscle may modulate the TPC force and the underlying increases in [Ca2+]i and play an important role in the induction of arrhythmias.

Actin Cytoskeleton↗
PubMed2001

Damage induced arrhythmias: mechanisms and implications.

Little is known about the role played by non-uniform myocardial stress and strain distributions and by non-uniform excitation contraction coupling in mechanisms underlying the premature beats that initiate an arrhythmia. We will review the evidence in support of a mechanism in which both non-uniform contraction and increased Ca2+ load of cells adjacent to acutely damaged cells are essential in the "spontaneous" generation of Ca2+ transients during the relaxation phase of the electrically driven twitch. The putative mechanism of initiation of the propagating Ca2+ waves involves feedback of rapid length (or force) changes to dissociation of Ca2+ from the contractile filaments. A novel aspect of this concept is that these mechanically elicited Ca2+ transients induce propagating Ca2+ waves that travel into the adjacent normal myocardium and cause after-depolarizations, which, in turn, may cause premature action potentials. These premature action potentials will further load the cells with Ca2+, which promotes the subsequent generation of propagating Ca2+ transients and leads to triggered arrhythmias. The damage-induced premature beats may also initiate re-entry arrhythmias in non-uniform myocardium. These observations strongly support the concept that abnormal cellular Ca2+ transport plays a crucial role in the initiation of arrhythmias in damaged and non-uniform myocardium.

Animals↗
PubMed2000

Aquaporin 4: lack of mRNA expression in the rat regenerating muscle fiber under denervation.

The recently identified water channel aquaporin 4 is a major component of the orthogonal arrays observed with freeze-fracture electron microscopy. We examined the expression of aquaporin 4 mRNA and protein in rat regenerating muscle under innervated and denervated conditions. We found decreased sarcolemmal immunostaining of aquaporin 4 in denervated regenerating muscle as opposed to innervated muscle. Quantitative reverse transcription-polymerase chain reaction revealed that aquaporin 4 mRNA was expressed in the innervated regenerating muscle; whereas it was not expressed in denervated muscle. Thus, lack of aquaporin 4 protein may be due to lack of aquaporin 4 mRNA in the denervated regenerating muscle. We conclude that the nerve supply influences expression of aquaporin 4 at the mRNA level in regenerating muscle.

Animals↗
PubMed2000

Aciculin and its relation to dystrophin: immunocytochemical studies in human normal and Duchenne dystrophy quadriceps muscles.

Aciculin is a novel adherens junction antigen extracted from human uterine smooth muscle that is reported to associate biochemically with dystrophin. We attempted to determine (i) the immunostainability of anti-aciculin antibody for the 6 histochemically normal human muscles and seven muscles from boys with Duchenne muscular dystrophy (DMD) and 11 disease control muscles, (ii) the ultrastructural localization of aciculin in normal skeletal myofibers, (iii) aciculin's spacial relationship with dystrophin and beta-spectrin, and (iv) if the aciculin is ultrastructurally colocalized with dystrophin, the distance from the aciculin epitope to the epitope of the dystrophin N- or C-terminal domain. For this, rabbit anti-aciculin antibody was generated against the synthetic peptide of aciculin fragment D [4]. Immunohistochemical staining showed that the immunostainability of DMD muscles for anti-aciculin antibody was markedly decreased as compared with normal and disease control muscles. Single and double immunogold labeling electron microscopy of 6 histochemically normal human quadriceps femoris muscles revealed that aciculin was present along the inner surface of muscle plasma membrane and that aciculin formed doublets more frequently with dystrophin (23.5 +/- 1.8%; group mean +/- SE) than with beta-spectrin (12.8 +/- 1.1%; P < 0.01 two tailed t test). Rabbit anti-aciculin antibody frequently formed doublets with monoclonal antibodies against the N- or C-terminal domain of dystrophin at the muscle cell surface. These results suggest that aciculin is associated with dystrophin and may interact with both the N- and C-terminal domains of dystrophin.

Child↗
PubMed2000

[Respiratory function impairment in patients with Parkinson's disease--a consideration on the possible pathogenetic relation to autonomic dysfunction].

To investigate the characteristics and clinical significance of respiratory function in patients with Parkinson's disease (PD), we studied 38 patients (male, 19; female, 19: mean age, 65.5 years: mean duration of disease, 6.7 years) who had no history of respiratory disease and smoking. Fifty three non-respiratory disease subjects (male, 26; female, 27: mean age, 67.6 years) were served as age-matched control. We measured spirometry and maximal expiratory flow-volume curve in all patients, and analyzed the relations between respiratory function variables and clinical profiles. The clinical disability of PD was indicated by Hoehn-Yahr (H-Y) scale. The number of PD patients was 15 in H-Y 2, 18 in H-Y 3 and 5 in H-Y 4, respectively. The values of % VC, %FEV 1, FEV 1/FVC, %PEFR, % V50 in H-Y 4 group were significantly smaller than those in H-Y 2 and 3 groups. Small airway dysfunction (SAD) was represented by abnormality of % V25, % V50/V25. The prevalence of impairment in % V25 and % V50/V25 was detected in 13 patients (34.2%) and 15 patients (39.5%), respectively, this was significantly higher than age-matched controls. However, the mean value and prevalence of impairment in % V25, % V50/V25 were not affected by H-Y scale and duration of disease or ideal body weight (%predicted value). Twenty seven patients showed normal ventilatory function based on % VC over 80% and FEV 1/FVC over 70%. The prevalence of impairment in % V25, % V50/V25 was detected in 8 patients (29.6%), 9 patients (33.3%), respectively, among 27 patients with normal ventilatory function. These results suggest that ventilatory dysfunction is concerned with clinical disability but SAD which is independent of clinical disability seen prevalently in patients with PD. It is widely accepted that patients with PD frequently have cardiac or bowel dysfunction based on the visceral autonomic dysfunction. We hypothesize that SAD may also be caused by possible autonomic dysfunction in patients with PD.

Aged↗
PubMed2000

[Juvenile onset Creutzfeldt-Jakob disease with the history of neurosurgical operation].

Juvenile onset Creutzfeldt-Jakob disease with the history of neurosurgical operation: a case report A 15-year-old boy gradually developed gait disturbance and dementia. After three months, his condition was deteriorated and he became a state of akinetic mutism. Then, he was transferred to our hospital. He had a history of neurosurgical operation for arterio-venous malformation in his right occipital lobe at the age of five. He showed myoclonus, periodic synchronous discharges in electroencephalogram, and a high cerebrospinal fluid level of neuron-specific enolase. He also revealed progressive brain atrophy by CT examination. He was diagnosed as having Creutzfeldt-Jakob disease (CJD). We could not detect gene mutation of prion protein. As far as we know, this is the youngest case of CJD in Japan. He is too young for the sporadic form of CJD. So the possibility of new variant form of CJD or iatrogenic CJD was considered, the former having been reported in England and the neighboring countries in Europe. However, new variant form of CJD was less likely because of the presence of definite PSD in EEG and the absence of the history of his stay in England. The relationship between the CJD onset and the neurosurgical operation was suggested, but no evidence such as frozen dura matter graft was proved.

Adolescent↗