Adopting a corporate perspective on databases. Improving support for research and decision making.

The Veterans Health Administration (VHA) is at the forefront of designing and managing health care information systems that accommodate the needs of clinicians, researchers, and administrators at all levels. Rather than using one single-site, centralized corporate database VHA has constructed several large databases with different configurations to meet the needs of users with different perspectives. The largest VHA database is the Decentralized Hospital Computer Program (DHCP), a multisite, distributed data system that uses decoupled hospital databases. The centralization of DHCP policy has promoted data coherence, whereas the decentralization of DHCP management has permitted system development to be done with maximum relevance to the users'local practices. A more recently developed VHA data system, the Event Driven Reporting system (EDR), uses multiple, highly coupled databases to provide workload data at facility, regional, and national levels. The EDR automatically posts a subset of DHCP data to local and national VHA management. The development of the EDR illustrates how adoption of a corporate perspective can offer significant database improvements at reasonable cost and with modest impact on the legacy system.

Phencyclidine-induced alterations of rat electrophysiology.

Phencyclidine (PCP) at high doses causes both excitation and depression in the rat. The visual evoked potential (VEP) was measured in rats following PCP administration in doses ranging from 1 mg/kg to 56 mg/kg. Consistent lengthening of VEP latencies suggests that PCP has an unusual inhibitory effect on visual function in the presence of the excitatory signs of bilaterally synchronous cortical spiking. The epileptogenic properties of PCP are quite evident in rats.

Naloxone epileptogenesis in monkeys.

The electroencephalographic effects of a range of doses of naloxone were evaluated in an effort to address the apparent epileptogenic properties of the drug. Electrographic activity was recorded from epidural electrodes in eight monkeys. The records were visually inspected and subjected to power spectral analyses. Concurrent visual evoked potentials were recorded and analyzed by standard procedures. Large doses (greater than 32.0 mg/kg i.m.) of naloxone were quickly and reliably succeeded by high voltage electrographic seizure activity at cortex. Lower doses (greater than or equal to 8.0 mg/kg) were followed by increased voltage in high frequency electroencephalogram (EEG) and spiking activity. Visual evoked potential latencies were reliably extended. As determined by power spectral analyses and third order slope analyses, the drug effects on EEG were related to time and dose. The early effects of high doses mimicked the maximal effects of low doses. It is concluded that seizures which follow high doses (48.0--64.0 mg/kg) of naloxone are derived from changes which are evident after doses which approach those used clinically to antagonize opiates. Such changes are, however, not readily apparent under visual inspection of the EEG.

Life-span alterations in visually evoked potentials and inhibitory function.

Visually evoked potentials (VEPs) elicited by patterned and unpatterned flashes were recorded from 211 healthy males aged 4-90 years. A measure of similarity between the two kinds of VEPs was obtained by correlating the digital values comprising the two waveforms. Across the life-span, correlations followed a U-shaped curve; patterned and unpatterned flash VEPs were most alike for the youngest and oldest subjects. This age effect, localized to scalp areas overlying visual cortex, is compatible with a concept of reduced inhibitory functioning within the visual systems of the young and the old. At central scalp, patterned and unpatterned flash VEP waveforms were more effectively differentiated by the right hemisphere. This observation agrees that the right hemisphere specializes in analyses of spatial material.