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Biomedical subjects

J A Moreira

Publications and source records attributed to J A Moreira.

4 recordsLinked to original sources

Hyperacute stroke: evaluation with combined multisection diffusion-weighted and hemodynamically weighted echo-planar MR imaging.

PURPOSE: To evaluate acute stroke with conventional, multisection diffusion-weighted (DW), and hemodynamically weighted (HW) magnetic resonance (MR) imaging. MATERIALS AND METHODS: The three MR imaging techniques were performed in 11 patients within 10 hours of the onset of acute hemiparesis. The volume of DW and HW abnormalities were compared with infarct volumes depicted at initial and/or follow-up MR or computed tomography (CT). RESULTS: Findings at DW and HW imaging were abnormal in nine of the 11 patients, despite normal findings at initial CT and/or MR. In all nine patients, infarcts were depicted at follow-up CT or MR. The DW abnormality was generally smaller and the HW abnormality was generally larger than the infarct volume determined at subsequent imaging. In the two patients with normal findings at DW and HW imaging, symptoms resolved completely within 1-48 hours. CONCLUSION: Different aspects of hyperacute cerebral ischemia are depicted at DW and HW imaging before infarction is depicted at conventional MR or CT. These techniques may improve stroke diagnosis and may contribute to advances in treatment.

Acute Disease

GABAergic neurotransmission in the C57BL/10 sps/sps mouse mutant: a model of absence seizures.

The C57BL/10 sps/sps mouse mutant displays generalized absence seizure-like behavior. In these mice, glutamic acid decarboxylase activity is reduced in the cortex and hippocampus. Tritiated flunitrazepam binding (3H-flu) is reduced in these areas, as well as in midbrain, cerebellum, and pons-medulla. Quantitative [3H]-flunitrazepam binding autoradiography confirms these observations. GABA uptake by synaptosomes from sps/sps mice is also reduced in all the areas studied. Potassium-stimulated, Ca(2+)-dependent release of radioactivity from synaptosomes preloaded with [14C]-GABA is reduced in the hippocampus, increased in midbrain and pons-medulla, but remains unaltered in the cortex. These results suggest region-specific alterations in GABAergic neurotransmission that may be responsible for the absence-like seizures in C57BL/10 sps/sps mice.

Animals

Altered GABAergic and glutamatergic transmission in audiogenic seizure-susceptible mice.

The C57BL/10 SPS/sps mouse mutant are audiogenic seizure-susceptible. The enzymatic activities of glutamate decarboxylase (GAD), GABA aminotransferase (GABA-T), alanine aminotransferase (ALA-T), aspartate aminotransferase (ASP-T), and glutamate dehydrogenase (GDH) of whole brain supernatant are significantly reduced in these epileptic mice. GABA uptake is decreased in cortex, midbrain, and pons medulla. Previous studies showed the presence of two sodium-dependent GLU uptake systems in normal (SPS/SP) mice. Glutamate Umax by System 1 is significantly decreased in these mice, whereas the Umax value for System 2 is significantly increased in the epileptic mice.

Acoustic Stimulation