Biomedical subjects
T W Anderson
Publications and source records attributed to T W Anderson.
Dentistry in the video age.
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Cold snaps, snowfall and sudden death from ischemic heart disease.
The short-term effect of low temperature on the incidence of ischemic heart disease over a 15-year period was examined. To reduce confounding by other seasonal factors the analysis was restricted to the winter months and was based on the change in the daily rate of sudden death at the time of cold snaps (arbitrarily defined as days on which the mean temperature was at least 4.4 degrees C lower than the day before) and around the time of heavy snowfalls. A statistically significant increase in the daily rate of sudden death at the time of cold snaps occurred only in men under 65 years of age, and even in this group the effect was of relatively small magnitude (+16%) compared with the large change in rate following heavy snowfalls (+88%). Among persons aged 65 years or over cold snaps had virtually no effect, and only the men in this group showed an increased daily rate of sudden death following a snowfall. These results suggest that much of the increased frequency of death from ischemic heart disease in winter, particularly among the elderly, must be due to factors other than short-term cold stress.
Does screening by "Pap" smears help prevent cervical cancer? A case-control study.
The Papanicolaou (Pap)-smear history of 212 cases of invasive cervical cancer was compared with that of 1060 age-matched controls drawn from neighbours. In the 5 years before the year of diagnosis 32% of the cases had been screened by Pap smear, compared with 56% of the controls. This difference was statistically highly significant (p less than 0.0001) and indicated a relative risk of invasive cancer of 2.7 in women who had not been screened by Pap smear, compared with those who had. Differences in Pap-smear history between cases and controls persisted when the data were stratified by age, income, education, marital history, smoking habit, employment status, and access to medical care. These results support the belief that the Pap smear is an effective screening procedure for invasive cervical cancer.
The male epidemic: 50 years of ischaemic heart disease.
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The sex differential in ischaemic heart disease: trends by social class 1931 to 1971.
The comparison of trends in ischaemic heart disease (IHD) mortality in different social classes is confounded by historical changes in diagnostic techniques and statistical classification, and possibly by different standards of diagnostic accuracy in the different social classes. The problems can be circumvented by taking advantage of the fact that in middle age (45 to 64) the IHD death rate is much higher in men than in women. This large sex differential is not present in any of the other causes of death with which IHD might easily be confused and it is therefore relatively unaffected by diagnostic errors and variation in classification. The changes that have occurred in the sex differential in Social Classes I and V in England and Wales between 1931 and 1971 confirm anecdotal clinical reports that the male vulnerability to IHD appeared first in Social Class I (professionsl). By 1971 Social Class V (unskilled) had caught up, and the men in these two social classes now experience an almost identical excess in cardiovascular death rate compared with their wives.
Vitamin C and the common cold.
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Vitamin C and the common cold.
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Vitamin C: cure for the common cold?
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Re-examination of some of the Framingham blood-pressure data.
Mathematical smoothing of data for the Framingham study leads to the conclusion that there is no threshold of normality for blood-pressure. A reasonable therapeutic goal might be "the lower the better". However, examination of the unsmoothed Framingham data indicates that while systolic pressures fit this no-threshold model reasonably well, changes in diastolic pressure below about 90 mm Hg have little or no prognostic significance. The poor fit of the diastolic points to the no-threshold model may also help to explain why at Framingham raised systolic pressure seemed to have a greater impact than raised diastolic pressure.
Cerebral infarction and myocardial infarction.
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Radiation exposures of Hanford workers: a critique of the Mancuso, Stewart and Kneale report.
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Staircase in frog ventricular muscle. Its dependence on membrane excitation and extracellular ionic composition.
Staircase was studied in frog ventricle strip preparations where it was possible to alter extracellular ionic composition extremely rapidly in the diastolic interval between beats. Several findings strongly indicate that staircase in this tissue is a result of progressively increasing calcium influx per beat, rather than a beat-by-beat augmentation of an intracellular calcium pool which contributes to activation. After a steady state of force development, the very next beat could be graded, from approximately zero force to the steady state value attained during the staircase progression, by grading the calcium concentration of a new Ringer's solution switched to perfuse the muscle in the diastolic period immediately before that beat. Also, action potentials, elicited during the "quiescent" period in the virtual absence of contraction (in 0.025 mm calcium Ringer's solution), markedly increase force development and accelerate the staircase seen upon return to normal Ringer's solution. Staircase is augmented and accelerated by prior exposure of the muscle, during the quiescent period, to calcium-poor media and markedly suppressed by prior exposure to sodium-poor media. Tetrodotoxin, in a dose that markedly slows the action potential upstroke, has no effect on staircase. Finally, staircase is seen to occur during a train of depolarizations (by voltage clamp) to inside positive levels greater than the equilibrium potential for sodium. It is concluded that changes in intracellular sodium concentration will alter the staircase response and may contribute to its genesis, but that this cannot be the sole cause of staircase.
Adjustment factors in mortality statistics. A word of caution.
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ABO-distribution and geographical differences in death-rates.
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Mechanism of activation of contraction in frog ventricular muscle.
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Large scale studies with vitamin C.
The combination of a regular daily supplement of vitamin C with extra dosage at the time of illness has been shown to reduce the disability due to common colds and other winter illness, but we have seen little effect on frequency of infections, sense of (well-being), or levels of serum cholesterol. The variable results that have been obtained from some other trials of vitamin C may be due in part to variation in the initial nutritional state of the subjects, with the greatest effects to be expected where there is most room for improvement. Because of the great variation in individual susceptibility to infection large numbers of subjects are required in these trials and they must be strictly double-blind. Although we have seen no clear evidence of harmful side-effects, occasional sensitivity to large doses of vitamin C cannot be ruled out, and the withdrawal depression of blood levels could conceivably interfere with a patient's ability to handle stress.