Pike. A nuclear gtpase that enhances PI3kinase activity and is regulated by protein 4.1N.

While cytoplasmic PI3Kinase (PI3K) is well characterized, regulation of nuclear PI3K has been obscure. A novel protein, PIKE (PI3Kinase Enhancer), interacts with nuclear PI3K to stimulate its lipid kinase activity. PIKE encodes a 753 amino acid nuclear GTPase. Dominant-negative PIKE prevents the NGF enhancement of PI3K and upregulation of cyclin D1. NGF treatment also leads to PIKE interactions with 4.1N, which has translocated to the nucleus, fitting with the initial identification of PIKE based on its binding 4.1N in a yeast two-hybrid screen. Overexpression of 4.1N abolishes PIKE effects on PI3K. Activation of nuclear PI3K by PIKE is inhibited by the NGF-stimulated 4.1N translocation to the nucleus. Thus, PIKE physiologically modulates the activation by NGF of nuclear PI3K.

Sequential expression of Trks A, B, and C in the regenerating olfactory neuroepithelium.

This study examines how the family of neurotrophin receptor tyrosine kinases (Trks) participates in the regeneration and replacement of olfactory neurons within the adult rat olfactory neuroepithelium. mRNA and protein products representing the high-affinity nerve growth factor (NGF) receptor Trk A, its family members Trk B and Trk C, and the low-affinity NGF receptor (INGFR) are all detected within both mature and regenerating olfactory neuroepithelium and within primary cultures of olfactory neurons. Cellular immunoreactivity for Trks A, B, and C and INGFR changes dramatically during the lifetime of an olfactory neuron and is demonstrated by inducing the epithelium into a coordinate rapid cycle of degeneration and regeneration in vivo by removal of the target organ, the olfactory bulb. Trk A-positive neuronal precursor basal cells undergo mitosis to produce Trk B-positive immature neurons that mature under the local influence of the olfactory neuroepithelium and the target-derived influence of the olfactory bulb to become a Trk C-positive mature neuron. Primary cultures of immature olfactory neurons demonstrate neurotrophin-induced phosphorylation of Trks A, B, and C and subsequent activation of the immediate early gene c-Fos, and they change their expression of differentiation stage-specific markers after treatment with individual and combinations of neurotrophins. This is the first population of neurons of a single lineage in which Trks A, B, and C and the INGFR have been demonstrated to be expressed sequentially during neuronal division, commitment, and differentiation and to be fully capable of transducing cellular signals causing phenotypic changes in differentiation state.

The role of L-type voltage dependent calcium channels in stimulated [3H]norepinephrine release from canine hippocampal slices following global cerebral ischemia and reperfusion.

The hippocampus is among those brain regions which are selectively vulnerable to ischemic damage. Hippocampal damage due to transient cerebral ischemia is mainly of the delayed, non-necrotic type which may arise after disruption or activation of specific cellular systems, including transmitter release through excitatory amino acid receptors. We investigated the contribution of L-type voltage dependent calcium channels (VDCCs) to glycine (GLY) potentiated N-methyl-D-aspartate (NMDA) receptor- and potassium-stimulated [3H]norepinephrine (NE) release in a canine model of global cerebral ischemia and reperfusion. Tissue was collected from four experimental groups: non-arrested controls (NA), global cerebral ischemia induced by 10 minute cardiac arrest (CA), and CA followed by 30 min or 24 hours reperfusion after restoration of spontaneous circulation. Brain slices prepared from all groups accumulated approximately equivalent amounts of [3H]NE. The sensitivity of [3H]NE release to stimulation by NMDA/GLY or elevated potassium was unchanged after ischemia and reperfusion. About 30% of release stimulated by the addition of 20 mM potassium was inhibited by the NMDA receptor-operated channel antagonist MK801 in all groups except CA in which only 4% of release was inhibited by MK801. The ability of 1 microM nitrendipine (NTP) to block stimulated release indicated that the contribution of the L-type VDCC to potassium or NMDA/GLY-stimulated release was significant only in NA and 24 hour reperfused animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased activation of L-type voltage-dependent calcium channels is associated with glycine enhancement of N-methyl-D-aspartate-stimulated dopamine release in global cerebral ischemia/reperfusion.

We investigated the relationships among N-methyl-D-aspartate, glycine, L-type voltage-dependent calcium channels, and [3H]dopamine release in a canine model of global cerebral ischemia/reperfusion. The binding of [3H]PN200-110 ([3H]isradipine) to L-type voltage-dependent calcium channels, that open as a consequence of N-methyl-D-aspartate-induced changes in membrane potential, was approximately doubled in striatal membranes prepared from ischemic animals relative to controls, and remained significantly elevated at 30 min and 2 h of reperfusion. These changes coincided temporally with changes in the ability of the voltage-sensitive calcium channel blocker nitrendipine to inhibit glycine enhancement of N-methyl-D-aspartate-stimulated [3H]dopamine release in striatal slices prepared from the same animals. Compared with nonischemic controls, N-methyl-D-aspartate-stimulated [3H]dopamine release was increased in ischemic animals and remained increased throughout reperfusion up to at least 24 h. Glycine enhanced N-methyl-D-aspartate-stimulated release in all treatment groups. The enhancement of N-methyl-D-aspartate-stimulated dopamine release by glycine was reduced by the inclusion of nitrendipine in striatal slices from ischemic and 30-min reperfused animals. These data suggest that glycine may facilitate opening of the voltage-dependent calcium channels activated by N-methyl-D-aspartate and that this facilitation is blocked by the antagonist nitrendipine.

Use of a modified cluster sampling method to perform rapid needs assessment after Hurricane Andrew.

STUDY OBJECTIVE: To rapidly obtain population-based estimates of needs in the early aftermath of Hurricane Andrew in South Florida. METHODS: We used a modified cluster-sampling method (the Expanded Programme on Immunization [EPI] method) for three surveys. We selected a systematic sample of 30 quarter-mile square clusters for each survey and, beginning from a random start, interviewed members of seven consecutive occupied households in each cluster. Two surveys were of the most affected area (1990 population, 32,672) at three and ten days after the hurricane struck; one survey was of a less affected area (1990 population, 15,576) seven days after the hurricane struck. MEASUREMENTS AND MAIN RESULTS: Results were available within 24 hours of beginning each survey. Initial findings emphasized the need for restoring utilities and sanitation and helped to focus medical relief on primary care and preventive services. The second survey of the most affected area showed improvement in the availability of food, water, electricity, and sanitation (P < or = .05). There was no evidence of disease outbreaks. CONCLUSION: For the first time, the EPI method provided population-based information to guide and evaluate relief operations after a sudden-impact natural disaster. An improvement over previous approaches, the EPI method warrants further evaluation as a needs assessment tool in acute disasters.