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G Choi

Publications and source records attributed to G Choi.

59 records · Page 4Linked to original sources
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Enhanced hippocampal CA1 LTP but normal spatial learning in inositol 1,4,5-trisphosphate 3-kinase(A)-deficient mice.

To define the physiological role of IP(3)3-kinase(A) in vivo, we have generated a mouse strain with a null mutation of the IP(3)3-kinase(A) locus by gene targeting. Homozygous mutant mice were fully viable, fertile, apparently normal, and did not show any morphological anomaly in brain sections. In the mutant brain, the IP4 level was significantly decreased whereas the IP3 level did not change, demonstrating a major role of IP(3)3-kinase(A) in the generation of IP4. Nevertheless, no significant difference was detected in the hippocampal neuronal cells of the wild-type and the mutant mice in the kinetics of Ca2+ regulation after glutamate stimulation. Electrophysiological analyses carried out in hippocampal slices showed that the mutation significantly enhanced the LTP in the hippocampal CA1 region, but had no effect on the LTP in dentate gyrus (DG). No difference was noted, however, between the mutant and the wild-type mice in the Morris water maze task. Our results indicate that IP(3)3-kinase(A) may play an important role in the regulation of LTP in hippocampal CA1 region through the generation of IP4, but the enhanced LTP in the hippocampal CA1 does not affect spatial learning and memory.

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PubMedDate not supplied

Oxyphil cells in a red-tailed hawk (Buteo jamaicensis) with nutritional secondary hyperparathyroidism.

A captive, immature red-tailed hawk (Buteo jamaicensis) was presented with multiple long-bone fractures, a serum calcium of 7.9 mg/dl, and a history of being fed an all-meat diet. Gross and microscopic examinations of the parathyroid glands revealed marked glandular hypertrophy and the presence of interlacing cords and clusters of light chief cells and oxyphil cells in approximately equal numbers. Bone sections showed severe fibrous osteodystrophy. These findings support the observation that the oxyphil cell is a product of continued stimulation, and they suggest that hypocalcemia may be a stimulating factor.

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PubMedDate not supplied

Nocardiosis in two Pesquet's parrots (Psittrichas fulgidus).

Nocardiosis is described in two Pesquet's parrots (Psittrichas fulgidus). Granulomatous lesions containing numerous branching, filamentous, acid-fast, gram- and methenamine silver-positive organisms were observed in sections of lung from both parrots, suggesting an oral-respiratory portal of entry. Thyroid follicular hyperplasia and osteoporosis were observed in one parrot, suggesting the presence of an underlying nutritional or metabolic defect.

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