Asian Science Citation Index is committed to provide an authoritative, trusted and significant information by the coverage of the most important and influential journals to meet the needs of the global scientific community.  
ASCI Database
308-Lasani Town,
Sargodha Road,
Faisalabad, Pakistan
Fax: +92-41-8815544
Contact Via Web
Suggest a Journal
 
Articles by T Ozawa
Total Records ( 2 ) for T Ozawa
  M Tada , A Kakita , Y Toyoshima , O Onodera , T Ozawa , T Morita , M Nishizawa and H. Takahashi
 

Multiple system atrophy (MSA) is a neurodegenerative disorder characterized by prominent autonomic failure with ataxia and/or parkinsonism. The leading cause of death in MSA is sudden death. We have shown that the early development of autonomic failure is an independent risk factor for sudden death. The depletion of sympathetic preganglionic neurons in the spinal intermediolateral cell column (IML) and its afferent medullary catecholaminergic and serotonergic neurons has been proposed to be partly responsible for autonomic failure in MSA. In this study, we investigated whether the depletion of neurons in any of these autonomic neuron groups contributes to sudden death in MSA. Out of 52 autopsy-proven patients with MSA, we selected 12 individuals who had died within 3.5 years after disease onset to define the accurate levels of slices and identify early neuropathological changes of autonomic nuclei in MSA. Four patients succumbed to sudden death and eight patients died through established causes. Serial 10 µm sections were obtained from the 8th segment of the thoracic cord and the rostral medulla oblongata. Sections from the medulla oblongata were immunostained for thyrosine hydroxylase and tryptophan hydroxylase. The total cell number in the five sections was computed for comparison. Compared with the control, the MSA group showed a marked depletion of neurons in the IML (38.0 ± 7.1 versus 75.2 ± 7.6 cells, P < 0.001), thyrosine hydroxylase-immunoreactive neurons in the ventrolateral medulla (VLM) (17.4 ± 5.1 versus 72.8 ± 13.6 cells, P < 0.01) and tryptophan hydroxylase-immunoreactive neurons in the VLM (15.6 ± 9.2 versus 60.8 ± 17.0 cells, P < 0.01), nucleus raphe obscurus (19.3 ± 4.4 versus 75.3 ± 8.6 cells, P < 0.001), nucleus raphe pallidus (2.1 ± 2.7 versus 9.0 ± 3.4 cells, P < 0.03), and arcuate nucleus (0.4 ± 0.8 versus 2.3 ± 1.5 cells, P < 0.05). Moreover, in patients who succumbed to sudden death, when compared with patients who had established causes of death, we found a marked depletion of tryptophan hydroxylase-immunoreactive neurons in the VLM (7.3 ± 3.5 versus 21.8 ± 6.5 cells, P < 0.02) and nucleus raphe obscurus (15.0 ± 2.0 versus 22.5 ± 2.1 cells, P < 0.01). The results indicate that the spinal IML and medullary catecholaminergic and serotonergic systems are involved even in the early stages of MSA, and the dysfunction of the medullary serotonergic system regulating cardiovascular and respiratory systems could be responsible for sudden death in patients with MSA.

  K Nakamura , H. E. F Palmer , T Ozawa and K. Mashima
 

Protein tyrosine phosphatase (PTP)-PEST is expressed in a wide variety of several cell types and is an efficient regulator of cell adhesion, spreading and migration. PTP-PEST-associating molecules are important in elucidating the function of PTP-PEST. Herein, we have identified protein phosphatase 1 (PP1) as a novel PTP-PEST binding protein, and then we aimed to determine how PP1 contributes to the phosphorylation at Ser39 of PTP-PEST, whose phosphorylation suppresses PTP-PEST enzymatic activity. The HEK 293 cells overexpressing exogenous PTP-PEST were stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) and the phosphorylation of PTP-PEST at Ser39 was evaluated using an anti-phospho-Ser39 PTP-PEST specific antibody (anti-pS39-PEST Ab). It was demonstrated that the phosphorylation at Ser39 detected by anti-pS39-PEST Ab was dependent on TPA treatment and a significant inverse correlation between the PTP activity of PTP-PEST and anti-pS39-PEST Ab-immunoreactive band intensity. The phosphorylation of Ser39 was suppressed by co-transfection of a plasmid encoding wild-type PP1, but not by that of the dominant-negative PP1 mutant. Furthermore, TPA-induced phosphorylation could take place in PTP-PEST catalytic domain, but the phosphorylation of PTP-PEST catalytic domain could not be abrogated by co-transfection of a plasmid expressing wild-type PP1. In conclusion, PP1 associates with the non-catalytic domain of PTP-PEST and regulates PTP activity via dephosphorylation of phospho-Ser39.

 
 
 
Copyright   |   Desclaimer   |    Privacy Policy   |   Browsers   |   Accessibility