PubMed Health⌕ Search

Biomedical subjects

D F Cooper

Publications and source records attributed to D F Cooper.

10 recordsLinked to original sources
PubMed1988

Shrinkage of centrifuged cement.

Two postulated mechanisms for the failure of prosthetic implants secured with bone cement are: failure of the cement itself, and loosening at the bone/cement interface. Failure rate with cement can be reduced by increasing the strength of the cement, and loosening can be reduced by minimizing cement shrinkage during polymerization. This paper shows that centrifuging cement to reduce porosity (and presumably increase strength) results in a substantial increase in cement shrinkage over uncentrifuged cement. A second set of experiments demonstrated that pressurization of cement to four atmospheres during polymerization resulted in tensile strengths comparable with those reported for centrifuged cement. Thus, the use of uncentrifuged bone cement, pressurized during polymerization, should minimize implant failure rates.

Atmospheric Pressure↗
PubMed1985

Copper and iron complexes catalytic for oxygen radical reactions in sweat from human athletes.

Sweat collected from 'explosive' and 'endurance' athletes immediately after exercise contains low molecular mass complexes of copper detectable by their ability to bind to o-phenanthroline. Concentrations of these copper complexes are much greater in arm sweat than in trunk sweat. The iron content of arm sweat, as determined by the ferrozine method, is also greater than that of trunk sweat. However, much of the iron in trunk sweat exists in a low molecular mass form that can bind to the antibiotic bleomycin, whereas the iron in arm sweat does not exist in this form. The metal complexes in human sweat are capable of stimulating the peroxidation of membrane lipids in the presence of ascorbic acid. The physiological significance of the presence of iron and copper complexes in sweat is discussed.

Anemia↗
PubMed1979

Perception of effort in isometric and dynamic muscular contraction.

The perception of muscular effort was studied using estimation and production methods in the adductor pollicis and quadriceps. A psychometric scale (percentage magnitude) was used. Static contractions were studied in the adductor pollicis, and both dynamic (isokinetic) and static contractions were studied in quadriceps. Linear and logarithmic equations were fitted for the perceived effort as a percentage of the maximum in relation to the produced percentage maximal force or torque. The logarithmic exponent was around or above 1.0. No significant difference was found between mean exponent and intercept values for the adductor pollicis and the quadriceps, or when estimated or produced values for the two muscles were compared. There was no difference in the same subjects between the equations for static and dynamic contractions with low angular velocity of the quadriceps.

Adult↗
PubMed1977

Exertion of stairclimbing in normal subjects and in patients with chronic obstructive bronchitis.

The exertion of stairclimbing has been studied in 10 normal young men, 10 healthy middle-aged men, and 10 middle-aged men with chronic bronchitis. Subjects climbed a staircase with a total vertical ascent of 40.8 m. They were allowed to adopt the most comfortable pattern of ascent, the patients having to stop at intervales for rest pauses. Work rate was determined by timing the raising body weight over measured sections of the staircase. Perception of exertion estimated with a numerical scale, heart rate, and increase of blood lactate concentration were closely similar in all three groups at the top of the staircase. In the patients, average power output was directly dependent on lung function, as indicated by the forced expired volume in 1 second. Stairclimbing offers a simple way of studying a patient's spontaneous activity pattern in a 'real life' environment. Studies of the kind described here could usefully complement formal exercise testing in the laboratory.

Adult↗