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M C Nishimura

Publications and source records attributed to M C Nishimura.

22 records · Page 2Linked to original sources
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Rat middle cerebral artery occlusion: evaluation of the model and development of a neurologic examination.

We have examined the incidence and size of infarction after occlusion of different portions of the rat middle cerebral artery (MCA) in order to define the reliability and predictability of this model of brain ischemia. We developed a neurologic examination and have correlated changes in neurologic status with the size and location of areas of infarction. The MCA was surgically occluded at different sites in six groups of normal rats. After 24 hr, rats were evaluated for the extent of neurologic deficits and graded as having severe, moderate, or no deficit using a new examination developed for this model. After rats were sacrificed the incidence of infarction was determined at histologic examination. In a subset of rats, the size of the area of infarction was measured as a percent of the area of a standard coronal section. Focal (1-2 mm) occlusion of the MCA at its origin, at the olfactory tract, or lateral to the inferior cerebral vein produced infarction in 13%, 67%, and 0% of rats, respectively (N = 38) and produced variable neurologic deficits. However, more extensive (3 or 6 mm) occlusion of the MCA beginning proximal to the olfactory tract--thus isolating lenticulostriate end-arteries from the proximal and distal supply--produced infarctions of uniform size, location, and with severe neurologic deficit (Grade 2) in 100% of rats (N = 17). Neurologic deficit correlated significantly with the size of the infarcted area (Grade 2, N = 17, 28 +/- 5% infarction; Grade 1, N = 5, 19 +/- 5%; Grade 0, N = 3, 10 +/- 2%; p less than 0.05). We have characterized precise anatomical sites of the MCA that when surgically occluded reliably produce uniform cerebral infarction in rats, and have developed a neurologic grading system that can be used to evaluate the effects of cerebral ischemia rapidly and accurately. The model will be useful for experimental assessment of new therapies for irreversible cerebral ischemia.

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Evaluation of 2,3,5-triphenyltetrazolium chloride as a stain for detection and quantification of experimental cerebral infarction in rats.

We have evaluated the use of 2,3,5-triphenyltetrazolium chloride (TTC) as an histopathologic stain for identification of infarcted rat brain tissue. The middle cerebral artery (MCA) of 35 normal adult rats was occluded surgically. At various times after surgical occlusion, rats were sacrificed and brain slices were obtained and stained with TTC or hematoxolin and eosin (H & E); the size of the area of infarcted tissue stained by each method was quantified. In rats sacrificed 24 hr after occlusion of the MCA, the size of the area of infarction was 21 +/- 2% of the coronal section for TTC, and 21 +/- 2% for H & E (mean +/- S.D., N = 13). The size of areas of infarction determined by either staining method was not significantly different in area by the paired test, and a significant correlation between sizes determined by each method was found by linear regression analysis (r = 0.91, slope = 0.89, and the y intercept = 4.4%). Staining with TTC is a rapid, convenient, inexpensive, and reliable method for the detection and quantification of cerebral infarction in rats 24 hr after the onset of ischemia.

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NMR in experimental cerebral edema: value of T1 and T2 calculations.

In an experimental investigation, the efficacy of nuclear magnetic resonance (NMR) relaxation times in measuring brain water was studied. Cerebral edema was induced in four dogs with a freeze lesion, which was produced by contact with a steel cylinder cooled in liquid nitrogen and placed on the exposed dural surface of the brain. NMR proton imaging was performed 2, 3, 6, or 24 hr after production of the lesion, at a field strength of 0.35 T, using multiparametric spin-echo (SE) technique. The animals were sacrificed immediately after imaging, and brain samples were analyzed for water content (wet-to-dry, microgravimetry). Correlation between water content, NMR imaging, and resulting T1, T2 relaxation times and mobile proton density values calculated with SE technique was performed. Brain sample analysis showed elevation of water content in the white matter subjacent to the lesion in all four dogs, rising at least 15% in each of the animals. NMR imaging detected the freeze lesion and subjacent vasogenic edema of the white matter in all animals. The 2 sec pulse interval SE technique was most sensitive in the detection of the abnormality, and provided optimal differentiation of gray and white matter. The second echo sampling (56 msec) was most sensitive to the detection of edema. The T1 and T2 relaxation values, as well as the mobile proton density values, were elevated in the normal gray matter and in the abnormal white matter when compared with normal white matter in any given animal.(ABSTRACT TRUNCATED AT 250 WORDS)

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