Biomedical subjects

Motohisa Suzuki

Publications and source records attributed to Motohisa Suzuki.

5 recordsLinked to original sources

PubMed2004

Protective effects of green tea catechins on cerebral ischemic damage.

BACKGROUND: Green tea catechins possess potent antioxidative properties, and the preventive effects against various oxidative diseases have been reported. The purpose of this study is to examine preventive and protective effects of green tea catechins on various deteriorative processes following stroke. MATERIAL/METHODS: Male Wistar rats were given ad libitum water with or without 0.25 and 0.5% tea catechin extract for 5 days prior to the operation and during the experiment. Right middle cerebral artery was occluded for 2 h, then reperfused for 22 h. Brain slices were stained with triphenyltetrazolim chloride to assess infarct area. Concentrations of plasma EGCg, and serum NOx were analyzed by HPLC. Detection of iNOS expression, neutrophil infiltration and peroxynitrite formation in the penumbra was performed by immunostain. Neurologic deficit was scored by posture reflex. RESULTS: Tea catechins dose-dependently reduced the brain infarct area and volume. Infarct volume was inversely correlated with plasma EGCg concentration. Dark staining for iNOS, neutrophils and peroxynitrite were observed in vessel wall of small arteries in control ischemic hemisphere, while in catechins (0.5%)-treated rats iNOS was detected slightly, and staining for neutrophils and peroxynitrite was not seen. Catechin ingestion blocked a 3-fold increase in serum NOx concentration in the jugular vein, and also reduced by 35% a 2-fold increase of plasma lipid peroxide level seen in control rats after reperfusion. Neurologic deficits were significantly alleviated by 0.5% catechin ingestion. CONCLUSIONS: Daily intake of green tea catechins efficiently protects the penumbra from irreversible damage due to cerebral ischemia, and consequent neurologic deficits.

Animals↗

PubMed2002

Concurrent formation of peroxynitrite with the expression of inducible nitric oxide synthase in the brain during middle cerebral artery occlusion and reperfusion in rats.

Peroxynitrite is assumed to play a crucial role in brain damage associated with the overproduction of nitric oxide (NO). The purpose of this study is to examine time-dependent changes of nitrite and nitrate (NOx) concentration in the circulation, and peroxynitrite formation as well as the expression of inducible nitric oxide synthase (iNOS) in the penumbra of rat brains during transient middle cerebral artery occlusion (MCAO) of Wistar rat for 2 h and reperfusion for 4-70 h. NOx concentration in the circulation was continuously monitored at the right jugular vein by microdialysis. The expression of iNOS was detected at 22-70 h after reperfusion in vascular walls and the cortex. Nitrotyrosine, a marker of peroxynitrite, appeared 4 h after reperfusion in the cortex, increasing substantially at 22-46 h in vascular walls. NOx level in dialysate increased immediately after MCAO. After a gradual decrease, the level increased again 4 h after reperfusion, reaching a maximum at 46 h. Brain myeloperoxidase activity, a marker of neutrophil infiltration, was not detected 4 h after reperfusion, but greatly increased at 22 h and then decreased. These results suggest that a marked increase of NOx level in the circulation might reflect the expression of iNOS, while neuronal NOS may contribute to peroxynitrite formation in the cortex observed at an earlier phase of reperfusion. This study indicates that monitoring NOx level in the circulation serves to assess the progress of stroke, and to determine appropriate therapeutic measures.

Animals↗

PubMed2002

Fluctuation of serum NO(x) concentration at stroke onset in a rat spontaneous stroke model (M-SHRSP). Peroxynitrite formation in brain lesions.

Malignant stroke-prone spontaneously hypertensive rats (M-SHRSP) develop hypertension and stroke at earlier ages than do nonmalignant SHRSP. Our previous findings suggested that reactive oxygen species were involved in the development of stroke in this strain. Nitric oxide (NO) which is more released at ischemia, might play a crucial role in stroke development by producing peroxynitrite, a neurotoxic substance. This study investigated whether the development of cerebrovascular lesion in M-SHRSP could be assessed by the fluctuation of serum NO(x) concentration, and whether peroxynitrite is associated with brain damage. Serum NO(x) levels were examined using an automated NO detector. Stroke-onset was temporally assessed according to a known method: changes in body weight, water intake, and neurologic symptoms. Cerebral lesions were confirmed by magnetic resonance imaging (MRI), and Evans blue extravasation at autopsy. MRI taken just after estimated stroke onset disclosed brain lesions. The baseline serum NO(x) level remained at 15-18 micromol/l, but the level gradually increased prior to stroke, and significantly at stroke onset. A marked rise in serum NO(x) occurred subsequently at poststroke. Immunohistochemical staining of nitrotyrosine, a peroxynitrite marker, was detected around vessels, neuronal cells and parenchyma in cerebral lesions. Stroke occurred in 50% of male M-SHRSP at 80 days of age. In conclusion, this study provides the first evidence for fluctuation of serum NO(x) at the onset of spontaneous stroke accompanying the appearance of peroxynitrite in brain lesions. Monitoring serum NO(x) would serve to assess the development of brain lesions at least in spontaneous stroke model.

Animals↗

PubMed2002

Beta-hydroxybutyrate, a cerebral function improving agent, protects rat brain against ischemic damage caused by permanent and transient focal cerebral ischemia.

In our previous study, beta-hydroxybutyrate (BHB) was found to prolong survival time and to inhibit cerebral edema by improving energy metabolism in the hypoxia, anoxia and global cerebral ischemia models. In this study, the cerebroprotective effect of BHB was examined in rats with permanent (p)-occlusion and transient (t)-occlusion of middle cerebral artery (MCA). BHB (30 mg x kg(-1) x h(-1) was continuously administered through the femoral vein. In rats with p-MCA occlusion, BHB significantly reduced infarct area at 24 h after the occlusion, but not at 72 h after the occlusion. In rats with 2-h t-MCA occlusion followed by 22-h reperfusion, BHB significantly reduced cerebral infarct area, edema formation, lipid peroxidation and neurological deficits. Moreover, in the t-MCA occlusion model, delayed administration of BHB started at 1 h after the initiation of the MCA occlusion also significantly reduced cerebral infarct area. Taking together the results obtained in our previous study into account, these results indicate that BHB decreased cerebral edema formation and infarct area by improving of the cerebral energy metabolism during ischemia and by inhibition of lipid peroxidation after reperfusion.

3-Hydroxybutyric Acid↗

PubMed2002

[Present status and tasks for future of point of care testing].

This paper introduces Point-Of-Care Testing(POCT) developed by Bayer, mainly focusing on urine dipstick and tests for Diabetes Mellitus. Urinalysis using a dipstick has been widely carried out as a screening test for various kinds of diseases. Ten-pad urine dipstick is commercially available at the present time, and the desktop instruments have been developed for automatic optical reading, such as the Clinitek 50/100/500 systems. More recently, Bayer developed a new urine dipstick intended for reliable detection of the early stage of kidney disease without the influence of urine condensation or dilution. The dipstick adds 2 pads to conventional urine dipsticks: one for the measurement of small amounts of protein(albumin), and the other for creatinine. A semi-quantitative urine protein-to-creatinine ratio is based on these results. There have been significant advances made in blood glucose meters for POCT in terms of reliability, simplicity of operation, sample volume, etc. And not only healthcare professionals but also patients with diabetes have used POCT meters. Dexter-ZII is available as one of these meters. DCA2000 is a portable analyzer for measuring HbA1c in 6 min. Patients could be treated and instructed on the basis of HbA1c measured by DCA2000. As one of the tasks for the future, it is preferable that some POCT systems be available as OTC for ordinary people to manage their own health. Also, I emphasize that it is important to review the usability of conventional urine dipsticks like a check for drug side effects, as well as for developing new urine analyses.

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