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K Sako

Publications and source records attributed to K Sako.

167 records · Page 10Linked to original sources
PubMedDate not supplied

Primary position upbeat nystagmus localizing value.

Primary position upbeat nystagmus has been associated predominantly with lesions of the midbrain, midline cerebellum, and lower brainstem. However, the precise localization still remains unclear. We report one case of primary position upbeat nystagmus in which magnetic resonance imaging showed probable bilateral lesions of the prepositus hypoglossi nuclei. Morphological and physiological studies have shown that this nucleus plays important roles in vertical eye movements. We conclude that the dysfunction of bilateral prepositus hypoglossi nuclei causes the upbeat nystagmus in our patient.

Adult↗
PubMedDate not supplied

Autoradiographic determination of brain pH following middle cerebral artery occlusion in the rat.

A method of quantitative autoradiography using 14C-labelled 5,5-dimethyl-2, 4-oxazolidinedione 14C-DMO to evaluate the local changes in brain pH after ischemia is described. In normal control rats the calculated tissue pH values in gray matter were slightly lower than those in white matter, and there was no significant difference in the calculated pH among the various structures in cortical and subcortical gray matter. Four hours after a left middle cerebral artery (MCA) occlusion, marked reductions in 14C-DMO concentrations were demonstrated in the anterior two-thirds of the cerebral cortex and in the lateral part of the caudate nucleus indicating tissue acidosis in these areas. Although several assumptions are required for the calculation of pH in brain tissue, this method would appear very useful in the investigation of the altered metabolic state in ischemic brain.

Animals↗
PubMedDate not supplied

Use of short-lived 18F and long-lived 14C in double tracer autoradiography for simultaneous measurement of LCBF and LCGU.

We have developed a quantitative autoradiographic technique for the simultaneous measurement of local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) using a combination of 14C-long-lived and 18F-short-lived radionuclides as labels. To obtain the LCGU image, a 50-fold greater radioactivity of 18F than of 14C was administered and the first exposure was done for 2 hours. Three days later, when most of the 18F had decayed, a second exposure was done for 5 to 6 days to obtain the LCBF image. 18F standards were prepared in each experiment. The technique provides, for the first time, the local glucose flow ratio (LGFR). LGFR, obtained by dividing the LCGU by the LCBF image, was expressed as percent mumol/ml (multiplied by 100). Measurement of these three values in the same animal is expected to prove useful in the investigation of the pathophysiology of the brain. The advantages of this method are that cross contamination is less than 4%, chemical or physical manipulation of the slices is unnecessary, and final results can be obtained within a week.

Animals↗
PubMedDate not supplied

Correlation of local cerebral blood flow, glucose utilization, and tissue pH following a middle cerebral artery occlusion in the rat.

The use of three sets of the double-tracer autoradiographic technique to measure topographical changes of local cerebral blood flow (LCBF), glucose utilization (LCGU), and tissue pH following a 3 h middle cerebral artery (MCA) occlusion in the rat is described. In a sham-operated group of animals there was 10% reduction of LCBF and 7% reduction of LCGU in the most affected areas as compared to the contralateral homologous regions. However, the ratio of LCGU/LCBF in the affected areas remained within normal limits. In the MCA-occluded animals, LCGU showed a bimodal response to decreased LCBF. LCGU decreased with reduced LCBF until LCBF fell to 38% of normal. Below this LCBF level LCGU increased, most likely implying anerobic glycolysis. Decline of tissue pH corresponds to the mismatch of LCBF and LCGU. These results suggest that brain tissue pH change cannot be predicted on the basis of LCBF or LCGU alone.

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