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Biomedical subjects

D W Watson

Publications and source records attributed to D W Watson.

At least 73 records · Page 4Linked to original sources
PubMed1972

A method for measuring human behavioural and physiological responses at different stress levels in a driving simulator.

1. A method is described by which a car simulator can be used to measure, simultaneously, motor-perceptual performance and physiological responses of human subjects under different levels of task difficulty or stress.2. Motor-perceptual performance was measured in terms of reaction times taken by subjects to carry out steering, braking and operation of traffic indicators in the simulator. Subjects were instructed to carry out the different driving manoeuvres by means of a command panel containing five coloured lights. Three levels of task difficulty or stress were devised. In level 1 only the light signals were used. In level 2 the driving simulator film was shown and all of the light signals reinforced the movements of the car in the film. Level 3 was similar to level 2, with the exception that whilst some of the light signals reinforced the movements of the car, others deliberately conflicted with it.3. Physiological responses measured were heart rate, blood pressure, respiration and calf blood flow. Personality was also measured by means of the Cattell 16 personality factor questionnaire.4. Analysis of variance of the performance of 15 subjects showed significant variation between the three task levels (P=<0.001 for steering reaction times; P=<0.01 for brake and indicator reaction times). In all cases the reaction times were longest for level 3, indicating that this was the most difficult task. The number of anticipated responses to steering, braking and traffic indicator signals was highest in level 2, while the number of corrections to steering and braking responses was lowest in level 2. None of these differences was statistically significant.5. Of the physiological variables, the heart rate showed a progressive increase from task levels 1 to 3 but only those between levels 1 and 3 were statistically significant (P<0.05).6. The results are discussed in relation to the validity of the method. It is concluded that by means of this method it is possible to produce controlled and reproducible degrees of stress and under conditions which are also suitable for the investigation of pharmacological agents upon it.

Adult↗
PubMed1972

The effects of cigarette smoking on the response to stress in a driving simulator.

1. Some behavioural and physiological responses of cigarette smokers and non-smokers exposed to varying degrees of stress in a driving simulator were compared.2. When the smokers were smoking a cigarette, some of their reaction times to light signals differed significantly from those of non-smokers, some being longer and some shorter. These differences disappeared when the smokers were not smoking.3. Of the physiological measurements, only heart rate differed significantly between smokers and non-smokers, being higher at all levels of stress in the smokers. There were no significant differences in blood pressure, calf blood flow and respiration rate between smokers and non-smokers.4. The results of the Cattell Sixteen Personality Factor Questionnaire showed that the smokers were significantly more extroverted and self-reliant than the non-smokers.5. The results are discussed in relation to the pharmacology of cigarette smoking. It is concluded that the differences in reaction times and heart rates between smokers and non-smokers were a consequence of cigarette smoking.

Adolescent↗
PubMed1971

Immunological studies in a patient with ulcerative colitis and sarcoidosis.

This report describes a patient with both ulcerative colitis and sarcoidosis. This association is of interest because of the anergy for cellular immunity which was characteristic of the sarcoidosis and the cytotoxic effect of the patient's lymphocytes for allogenic colon epithelial cells which characterized the ulcerative colitis. This concordance of immunological findings suggests that the cytotoxic effect may have a basis other than cellular immunity.

Barium Sulfate↗
PubMed1970

Puffing frequency and nicotine intake in cigarette smokers.

The smoking behaviour of 36 subjects smoking cigarettes with different filter retention efficiencies for nicotine was studied. Subjects were observed while performing various tasks on a driving simulator and also during a resting period after the tasks. Smokers of cigarettes with high-retention filters took more frequent puffs and obtained nearly the same amount of nicotine as smokers of cigarettes with low-retention filters, both while performing the tasks and during the resting period. Smokers of both types of cigarettes took significantly more puffs and obtained more nicotine per unit time during the resting period than during the tasks. The results are compatible with the possibility that smokers automatically adjust the nicotine dose obtained from a cigarette to some "optimum" level which may vary with different activities.

Adult↗
PubMed1970

A purified group A streptococcal pyrogenic exotoxin. Physiochemical and biological properties including the enhancement of susceptibility to endotoxin lethal shock.

Purified pyrogenic exotoxin from Group A streptococcal filtrates (Streptococcus pyogenes, type 10, strain NY-5) has been characterized primarily as a protein complexed with hyaluronic acid. Amino acid composition and analysis revealed a typical acidic protein with an average molecular weight of 29,000. The purified exotoxin was free of streptolysins O and S, nicotinamide adenine dinucleotidases (NADases), deoxyribonucleases (DNases), mucopeptide, and endotoxins. The biological activity was destroyed when the exotoxin was heated at 65 degrees C for 30 min or boiled for 2 min. The biological activities investigated were pyrogenicity in rabbits (minimal pyrogenic dose-3 hr, 0.07 microg/kg), lethality in rabbits (LD(50), 3500 microg/kg), skin test dose in human skin (> 10(9) skin test doses, per mg toxin), cytotoxicity of rabbit spleen macrophage (Cytotoxic Index 0.5-10 microg/ml), enhancement of susceptibility to endotoxin shock (in rabbits > 100,000-fold), and antigenic analysis (A-type toxin). The exotoxin was immunogenic and it was possible, therefore, to immunize animals against the various toxic activities. The immunity was specific for the A-type toxin. The clinical implications of the highly significant enhancement effect of these exotoxins are discussed. It is suggested that clinical or subclinical infection with Group A streptococci could prepare the host for fatal shock from Gram-negative infections or the inadvertent injection of small amounts of Gram-negative bacterial endotoxins.

Animals↗