Neuroprotective Efficacy of YM872, an ␣-Amino-3-Hydroxy-5- Methylisoxazole-4-Propionic Acid Receptor Antagonist, after Permanent Middle Cerebral Artery Occlusion in Rats

ABSTRACT The neuroprotective efficacy of YM872, a novel, highly watersoluble ␣-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist, was investigated in rats subjected to permanent occlusion of the left middle cerebral artery. The rats were assessed either histologically or neurologically 24 hr or 1 wk after ischemia. YM872 was intravenously infused for either 4 or 24 hr at dose rates of 0 to 20 mg/kg/hr starting 5 min after ischemia to examine the effect of prolonged treatment. YM872 was then infused at 20 mg/kg/hr beginning 0 to 4 hr after ischemia to determine the efficacy time window. Additionally, a 20 mg/kg/hr dose rate of YM872 was infused for 4 hr in single day-or 5-day repetitive-administrations to evaluate long-term benefits of the drug. YM872 significantly reduced infarct volume in both 4-and 24-hr treatment groups measured 24 hr after ischemia. No difference was observed in the degree of protection between length of infusion. Significant neuroprotection was maintained even when drug administration was delayed up to 2 hr after ischemia. A single YM872-administration significantly improved neurological deficit and reduced infarct volume (30%, P Ͻ .01) measured 1 wk after ischemia. YM872 treatment did not induce such adverse effects as physiological changes, serious behavioral abnormalities or nephrotoxicity. These data suggest that the ␣-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor plays a crucial role in the progression of neuronal damage in the early phase of ischemia and that YM872 may be useful in treating acute ischemic stroke

Shallow seismic reflection profiling across the western marginal faults of Kitakami Lowland, northern Honshu Island, Japan

In 1997-1998, integrated passive and active seismic experiments were conducted in northern Honshu, Japan. These experiments aimed at understanding the relationship between earthquake occurrence and deformation process of the intra-island-arc crust. In the summer of 1998, a shallow seismic reflection survey was conducted to obtain the fault’s detailed geometry to depths of 1km across the western marginal faults of Kitakami Lowland, Iwate Pref., Japan. The seismic source was a mini-vibrator. The data set recorded by the digital telemetry system was processed using seismic reflection technique. Imaging was preformed using conventional common mid-point processing steps, including post-stack migration and depth conversion. A reflection image shows the deep geometry of the Uwandaira fault, which is positioned at the eastern edge of the Ou Backbone range

High-resolution seismic reflection profiling across the surface rupture associated with the 2004 Mid-Niigata Prefecture earthquake, central Japan : data acquisition and processing

The 200.4 Mid-Niigata Prefecture earthquake (Mj 6.8) generated surface ruptures along the eastern rim of the Uonuma hills. To reveal the relationship between a seismogenic source fault and surface ruptures, shallow, high-resolution seismic reflection profiling was undertaken across the surface ruptures and the active faults. The seismic source was a mini-vibrator and seismic data were recorded by a digital telemetry system. The source and receiver interval was 10 m4 The seismic data were processed using conventional CMP seismic reflection methods. The resultant depth-converted seismic section portrays an emergent thrust beneath the surface rupture associated with the Mid-Niigata Prefecture earthquake

High-resolution seismic reflection profiling across the Shiraiwa fault, eastern margin of the Yokote basin fault zone, northeast Japan : data acquisition and processing

The eastern margin of the Yokote basin fault zone extends about 56km at the western foot of the Ou Backbone Range, northeast Japan. The Rikuu earthquake (M=7.2) occurred in the Ou Backbone Range (Mahiru Range) on 31st August, 1896. Associated with this earthquake, four thrust faults-Obonai, Shiraiwa, Ota, and Senya fault3 appeared on the surface of the western foot of the Mahiru Range. These faults were highly sinuous with numerous gaps and en echelon steps. We conducted a high-resolution seismic reflection profiling survey across the Shiraiwa fault. The obtained seismic reflection data were processed by conventional common mid-point methods, post-stack migration, and depth conversion. The subsurface structure across the Shraiwa fault is characterized by branched low-angle reverse faults and conjugate back-thrust. The emergent thrust associated with the 1896 earthquake is regarded to be a subsidiary reverse fault

High-resolution seismic reflection profiling across the Senya fault at Hanaoka, northern Honshu, Japan: Data acquisition and processing

The Senya fault, northern Honshu, Japan, which generated the Rikuu earthquake (Mj 7.2) 1896, is a typical intra-arc active thrust. Subsurface geometry provides essential information for better understanding strong ground motions and crustal deformation processes. A high-resolution seismic reflection survey was conducted along the 63km long seismic line across the toe of the thrust to reveal the subsurface geometry. The seismic source was a Mini-vibrator truck and the receiver interval was 10 m. The seismic data were processed by the standard common mid-point method. The Senya fault is clearly identified as a boundary between horizontal reflectors of the basin fill in the Yokote basin and moderately dipping reflectors beneath the Senya hills. The thrust occurred in late Miocene mudstone, and shows a flat and ramp geometry. The emergent thrust dips 30 degrees down to 500m, and changes its dip to subhorizontal following the distribution of the mudstone