Spectroscopic evidence of hippocampal abnormalities in neocortical epilepsy.

Lesional neocortical epilepsy (NE) can be associated with hippocampal sclerosis or hippocampal spectroscopic abnormalities without atrophy (dual pathology). In this study, magnetic resonance spectroscopic imaging (MRSI) was used to determine the frequency of hippocampal damage/dysfunction in NE with and without structural lesion. Sixteen patients with NE [seven temporal NE (NE-T), nine extratemporal (NE-ET)] and 16 controls were studied with a 2D MRSI sequence (Repetition time/echo time (TR/TE) = 1800/135 ms) covering both hippocampi. Seven NE patients had MR visible lesions (NE-Les), nine had normal MRI (NE-no). In each hippocampus, 12 voxels were uniformly selected. In controls, mean (+/- SD) NAA/(Cr + Cho) values for each voxel were calculated and voxels with NAA/(Cr + Cho) < or = (mean in controls--2SD in controls) were defined as 'pathological' in patients. Eight of 16 NE patients had at least two 'pathological' voxel (mean 2.5, range 2-5) in one hippocampus. Four were NE-Les and four NE-no. Three (43%) NE-T patients, had evidence for hippocampal damage/dysfunction and five (56%) had NE-ET. The ipsilateral hippocampus was affected in six of eight NE patients. Evidence for unilateral hippocampal damage/dysfunction was demonstrated in 50% of the NE patients. The type of NE, i.e. NE-Les or NE-no, NE-T or NE-ET, had no influence on the occurrence of hippocampal damage/dysfunction.

Safety observations in phase I clinical evaluation of the Excorp Medical Bioartificial Liver Support System after the first four patients.

A Phase I clinical safety evaluation of the Excorp Medical, Inc, Bioartificial Liver Support System (BLSS) is in progress. Inclusion criteria are patients with acute liver failure of any etiology, presenting with encephalopathy deteriorating beyond Parson's Grade 2. The BLSS consists of a blood pump, heat exchanger to control blood temperature, oxygenator to control oxygenation and pH, bioreactor, and associated pressure and flow alarm systems. Patient liver support is provided by 70-100 g of porcine liver cells housed in the hollow fiber bioreactor. A single support period evaluation consists of 12 hour extracorporeal perfusion with the BLSS sandwiched between 12 hours of pre (baseline) and 12 hours of post support monitoring. Blood chemistries and hematologies are obtained every 6 hours during monitoring periods and every 4 hours during perfusion. Physiologic parameters are monitored continuously. The patient may receive a second treatment at the discretion of the clinical physician. Preliminary evaluation of safety considerations after enrollment of the first four patients (F, 41, acetaminophen induced, two support periods; M, 50, Wilson's disease, one support period; F, 53, acute alcoholic hepatitis, two support periods; F, 24, chemotherapy induced, one support period) is presented. All patients tolerated the extracorporeal perfusion well. All patients presented with hypoglycemia at the start of perfusion, treatable by IV dextrose. Transient hypotension at the start of perfusion responded to an IV fluid bolus. Only the second patient required heparin anticoagulation. No serious or unexpected adverse events were noted. Moderate biochemical response to support was noted in all patients. Completion of the Phase I safety evaluation is required to fully characterize the safety of the BLSS.

Assessment of need for transport tubes when continuously monitoring for radioactive aerosols.

Aerosol transport tubes are often used to draw aerosol from desirable sampling locations to nearby air sampling equipment that cannot be placed at that location. In many plutonium laboratories at Los Alamos National Laboratory, aerosol transport tubes are used to transport aerosol from the front of room ventilation exhaust registers to continuous air monitors (CAMs) that are mounted on nearby walls. Transport tubes are used because past guidance suggests that extraction of aerosol samples from exhaust locations provides the most sensitive and reliable detection under conditions where the rooms have unpredictable release locations and significant spatial variability in aerosol concentrations after releases, and where CAMs cannot be located in front of exhaust registers without blocking worker walkways. Despite designs to minimize particle loss in tubes, aerosol transport model predictions suggest losses occur lowering the sensitivity of CAMs to accidentally released plutonium aerosol. The goal of this study was to test the hypotheses that the reliability, speed, and sensitivity of aerosol detection would be equal whether the sample was extracted from the front of the exhaust register or from the wall location of CAMs. Polydisperse oil aerosols were released from multiple locations in two plutonium laboratories to simulate plutonium aerosol releases. Networked laser particle counters (LPCs) were positioned to simultaneously measure time-resolved aerosol concentrations at each exhaust register (representative of sampling with transport tubes) and at each wall-mounted CAM location (representative of sampling without transport tubes). Results showed no significant differences in detection reliability, speed, or sensitivity for LPCs positioned at exhaust locations when compared to LPCs positioned at the CAM wall location. Therefore, elimination of transport tubes would likely improve CAM performance.

Evaluation of continuous air monitor placement in a plutonium facility.

Department of Energy appraisers found continuous air monitors at Department of Energy plutonium facilities alarmed less than 30% of the time when integrated room plutonium air concentrations exceeded 500 DAC-hours. Without other interventions, this alarm percentage suggests the possibility that workers could be exposed to high airborne concentrations without continuous air monitor alarms. Past research has shown that placement of continuous air monitors is a critical component in rapid and reliable detection of airborne releases. At Los Alamos National Laboratory and many other Department of Energy plutonium facilities, continuous air monitors have been primarily placed at ventilation exhaust points. The purpose of this study was to evaluate and compare the effectiveness of exhaust register placement of workplace continuous air monitors with other sampling locations. Polydisperse oil aerosols were released from multiple locations in two plutonium laboratories at Los Alamos National Laboratory. An array of laser particle counters positioned in the rooms measured time-resolved aerosol dispersion. Results showed alternative placement of air samplers generally resulted in aerosol detection that was faster, often more sensitive, and equally reliable compared with samplers at exhaust registers.