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Biomedical subjects

G R Wright

Publications and source records attributed to G R Wright.

27 records · Page 2Linked to original sources
PubMed1978

Protection against the physiological effects of positive pressure breathing.

The degree of protection afforded by three jerkin G-suit systems (British, Canadian and Swedish) using different pressures against the adverse physiological effects produced by high levels (50 mm Hg and 70 mm Hg) of positive pressure breathing (PPB) was investigated at ground level in 10 male subjects. The British and Canadian systems were evaluated with G-suit pressure equal to breathing pressure and 3.2 times breathing pressure, whereas the Swedish system was studied only with 3.2 times breathing pressure in the G suit. The experimental design was a 10 X 10 Latin swuare. PPB produced significant increases in heart rate, peripheral resistance, and systolic, diastolic and mean arterial blood pressures, and significant decreases in stroke volume and cardiac output. These effects were directly related to the level of PPB. Our results show that the British system provides the highestdegree of protection against PPB, followed by the Swedish and the Canadian systems. It was also found that a G-suit pressure of 3.2 times breathing pressure significantly increases the degree of protection afforded by the British and Canadian systems.

Adult↗
PubMed1975

Carbon monoxide in the urban atmosphere: hazards to the pedestrian and the street-worker.

The carbon monoxide (CO) concentrations encountered by pedestrians and workers in the streets of a large metropolis were monitored by a reliable and sensitive portable detector (the Ecolyzer). Up to 1,000 observations per day were collected for several months during the summer and fall of 1973. The CO levels ranged from 10 to 50 ppm (varying with wind speed and direction, atmospheric stability, traffic density, and the height of nearby buildings). Much higher average concentrations were found in such adverse sites as poorly ventilated underpasses and underground garages. Street closures for a pedestrian mall reduced levels on the mall to around the general urban background withoug large increases in readings on adjoining streets. Many street-workers have little medical supervision, and for this reason the urban eight-hour CO ceilings may be a more appropriate air quality target than the usual industrial figure of 50 ppm. However, even the latter is sometimes exceeded on busy city streets.

Air Pollution↗
PubMedDate not supplied

Pharmacokinetics of antipyrine, warfarin and paracetamol in the brushtail possum.

The plasma pharmacokinetics of antipyrine, warfarin and paracetamol have been studied in the Australian brushtail possum (Trichosurus vulpecula). The plasma elimination half-lives (t1/2) were 1.2 h for antipyrine, 11.9 h for warfarin and 5.2-12.9 h for paracetamol. Our data indicate that the clearance of these three xenobiotics in the possum is similar to that reported in eutherian mammals. There was no dose-dependent increase in paracetamol plasma t1/2 over the dose range 100-1000 mg kg(-1), indicating a lack of capacity saturation. This observation may in part explain the unusual resistance of the possum to the hepatotoxic effect of high doses of paracetamol.

Acetaminophen↗
PubMedDate not supplied

Brake reaction time--effects of age, sex, and carbon monoxide.

Simulated braking responses have been tested in relation to blood carboxyhemoglobin (HbCO) levels. The main determinants of percentage of HbCO in 352 subjects attending a fall fair were daily cigarette consumption and minutes since the last cigarette. In women the brake response time deteriorated from age 16 yr, but in the men there was an improvement from age 16 to the early 20s. Times at all ages were better for men than for women. Average response times and the rate of aging of the braking response were very similar in smokers and in nonsmokers. In the nonsmokers, however, response time with step function CO increments of as much as 7% HbCO. There was a suggestion of a small increase of reaction time, with an opposing decrease of leg movement time, during the first few minutes after CO exposure; nevertheless, these trends were statistically insignificant.

Adult↗
PubMedDate not supplied

Carbon monoxide exposure and auditory duration discrimination.

Two young adults performed an auditory duration discrimination task while sitting in an open office (i.e., without sensory isolation). The percentage of errors rose when carboxyhemoglobin (HbCO) readings of 3.2% or 4.7% were produced by a rebreathing method; there was a parallel but statistically insignificant trend at 2.0% HbCO. Analysis of the data by psychophysical measures, however, showed no significant changes of difference threshold, criterion value, or point of subjective equality. After the tape was rearranged to meet criteria of a constant interval, a balanced order of presentation, and psychological rather than physical equality of tone length, eight young adults performed the task better in an isolation booth than in an open office, scores in both situations being unaffected by increases of HbCO to greater than 8%. Further trials with five young adults compared responses before and after administration of 80 ml of CO (HbCO 4.92%); again, no effect of carbon monoxide was seen relative to control experiments. The error score of nonsmoking young adults can be increased by a level of HbCO as low as 3.2%. The likelihood of such a response, however, is markedly influenced by task difficulty, environment, and the arousal of the subjects. Furthermore, the nature of the functional disturbance remains uncertain; psychophysical measures show no significant impairment of auditory duration discrimination.

Adult↗