Biomedical subjects
Publications and source records attributed to B Ellertsen.
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UNLABELLED: Two groups of divers were compressed to 500 msw with heliox (n = 3) and trimix (n = 3). They were followed with repeated neuropsychological and neurological tests during compression, at stable intermediate depths, and at 500 msw. For the heliox group there was a marked increase in tremor and EEG slow waves and reduction in handgrip strength. For the trimix group the tremor increase did not occur, but the EEG changes were the same as in the heliox group. On motor tests only the trimix group showed impaired finger dexterity and manual dexterity. The same occurred for fine visuomotor coordination, but both groups had increased intentional tremor. On cognitive tests the same difference occurred. The trimix group was markedly impaired in reasoning and long-term memory, while only a mild impairment was found in the heliox group. Dizziness and other symptoms of high pressure nervous syndrome (HPNS) occurred in both groups. CONCLUSION: There were marked HPNS effects during compression for both groups. Only tremor was inhibited by the nitrogen. In addition, the trimix group was impaired because of nitrogen narcosis. These data indicated that 10% nitrogen did not inhibit HPNS effects during compression to 500 msw, but the considerable differences between subjects shows that susceptibility to compression must be an important area for future research.
Cardiovascular responses to strong auditory stimulation were compared in common migraine patients and controls. Two matched groups of eight subjects participated in two laboratory sessions. During each session, baseline recording of the cardiovascular variables was followed by twenty auditory stimuli (95 dB, 1000 Hz), sounded at irregular intervals. Phasic responses in heart rate and pulse wave amplitudes in the superficial temporal arteries were measured. A post stimulation sampling period ended each session. Different cardiovascular response patterns were found in the two groups. The migraine patients showed more pronounced heart rate responses and slower habituation to stimulation. Stronger pulse wave amplitude reduction during stimulation and an increase during the post stimulation period was also found in the migraine group.
UNLABELLED: Two groups of divers were compressed to 300 msw (984 fsw) with heliox (n = 3) and trimix (n = 3). Neuropsychological/neurological testing was performed repeatedly during the compression and on reaching 250 (820 fsw) and 300 msw. On the second day the trimix group was tested before and after a gas change to heliox. For the heliox group there was a marked increase in tremor and EEG slow waves, and reduction of alpha band and in hand-grip strength. For the trimix group visuomotor coordination was impaired. In the cognitive performance tests the heliox group was most impaired at 250 msw, whereas the trimix group was most impaired at 300 msw. Before the gas change to heliox the trimix group showed impaired performance in some tests. After the gas change, performance returned to predive levels, except for perceptual speed. There was an increase in tremor immediately after the gas change. CONCLUSION: There was a marked HPNS effect during compression on heliox. This effect was not observed in the trimix group, but this group was mildly intoxicated on reaching saturation depth. The tests indicated slight narcotic effects also after 26 h, but this disappeared after the change in heliox.
Since recent reviews of the behavioural effects of septal lesions agree that more than one explanatory concept is required, a multivariate analysis of the septal syndrome has been made. A total of 127 rats have been tested 73 with septal lesions and 54 controls. The rats were tested in a standard test battery consisting of a residential maze, spontaneous alternation, spatial learning, approach/avoidance conflict and one-way active avoidance. Factor analyses reveal a complex change in the factor structure after septal lesions. None of the previous explanations of septal functions receives unequivocal support. The findings do not exclude the possibility that septal lesions interfere with a few general behaviour mechanisms or perhaps only one. However, if so, this factor does not explain as much of the variance as expected. Situational or test-dependent factors play a greater role in the variance. This is interpreted as an indication of insufficiency in the theoretical structure, or in conventional test designs.
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Fifteen women with pharmacologically intractable epilepsy were given physical exercise (aerobic dancing with strength training and stretching) for 60 min, twice weekly, for 15 weeks. Seizure frequency was recorded by the patients for 3-7 months before the intervention, during the intervention period, and for 3 months after the intervention. Medication and other known seizure-influencing factors were kept as constant as possible. Self-reported seizure frequency was significantly reduced during the intervention period. The exercise also led to reduced level of subjective health complaints, such as muscle pains, sleep problems, and fatigue. The exercise reduced plasma cholesterol ratio and increased maximum O2 uptake. Because most of the patients were unable to continue the exercise on their own after the intervention period, the exercise effects were not maintained during the follow-up period. The patients were not unwilling to continue the exercise, but it was not sufficient to offer them the possibility of continuing similar types of exercise. We believe that 15 weeks is too short a time to establish a life-style change and that continued physical exercise for these patients requires a well-organized and supportive program, requiring experienced and dedicated instructors.