David J. Horrigan

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Blood biochemical parameters were measured in 12 male human subjects before and after exposure to a staged decompression protocol, with simulated extravehicular activity, during 3 days. Following the exposure, significant changes occurred in several parameters, including increases in blood urea nitrogen, inorganic phosphate, potassium, and osmolality, and(More)
The purpose of this study was to determine the effect of extended O2 prebreathing on symptom and bubble incidence during decompressions simulating extravehicular activity. The 38 subjects breathed O2 for a 6-h period prior to decompression to 4.3 psi. The subjects performed upper body exercise for 6 h. Subjects were monitored with a Doppler bubble detector(More)
1. The modulatory effect of serotonin on CA1 pyramidal cells in the hamster (Mesocricetus auratus) hippocampus was examined over a range of temperatures. 2. Following repetitive Schaffer collateral/commissural stimulation, changes in the amplitude of population spikes (the synchronous firing of CA1 pyramidal cells) were recorded in the hamster, a(More)
Without adequate hydration, profound heat stress and dehydration can occur in people who work in hot environments. This study evaluated the effectiveness of three beverages on temperature regulation, cardiovascular response, and work performance during 60 h of dry heat exposure. Volunteer subjects lived in a climatic chamber in simulated desert conditions(More)
Serotonergic fibers project to the hippocampus, a brain area previously shown to have distinctive changes in electroencephalograph (EEG) activity during entrance into and arousal from hibernation. The EEG activity is generated by pyramidal cells in both hibernating and nonhibernating species. Using the brain slice preparation, we characterized serotonergic(More)
The effects of 7 day exposure to 2G fields on serotonergic modulation at two synapses on a hippocampal pathway were examined by recording dentate gyrus and CA1 pyramidal cell layer electrical activity. Serotonin decreased the amplitude of the population spike (synchronous action potentials in hundreds of neurons) in both the dentate gyrus and CA1 regions of(More)
Eight human volunteers, individually studied in a hyperbaric chamber, breathed: 1) air at 1 ATA; 2) 80% argon and 20% oxygen and 1 ATA for 30 min; 3) air at 1 ATA for 30 min; 4) 100% 02 at 1 ATA for 30 min; 5) air at 1 ATA for 30 min; 6) 100% O2 at 2 ATA for 60 min; and 7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and(More)
The majority of the environmental factors which comprise the spacecraft and space suit environments can be controlled at "Earth normal" values, at optimum values, or at other values decided upon by spacecraft designers. Factors which are considered in arriving at control values and control ranges of these parameters include physiological, engineering,(More)
A study was performed to evaluate decompression procedures suggested for use prior to Space Shuttle extravehicular activity. Hematological parameters were measured in 12 male human subjects before and after exposure in an altitude chamber to a 3-day staged decompression schedule, with simulated extravehicular activity. Following the exposure, significant(More)