Biomedical subjects
B K Armstrong
Publications and source records attributed to B K Armstrong.
Cutaneous malignant melanoma in women: exogenous sex hormones and reproductive factors.
The roles of exogenous sex hormones and reproductive factors in the causation of malignant melanoma of the skin in women were examined in a case-control study of 276 patients and 276 matched controls in Western Australia. There was no consistent evidence of a relationship between the incidence rates of different histogenetic types of melanoma and age at menarche, duration of menstrual life, degree of obesity, number of pregnancies more than 20 weeks in duration or use of oral contraceptive preparations (OCP). Exposure to OCP was examined separately for different age periods and in different intervals of time before diagnosis; no consistent trend emerged. There was borderline evidence of an association of superficial spreading melanoma with duration of use of unopposed oestrogens. On the basis of seven studies of the relationship of melanoma to OCP published to date, we estimate that the total incidence rate of melanoma in OCP ever-users is unlikely to be increased by more than one third the rate in never-users.
Dietary-induced changes in the fatty acid composition of human cheek cell phospholipids: correlation with changes in the dietary polyunsaturated/saturated fat ratio.
Healthy normotensive volunteers aged 20 to 59 yr were randomly allocated either to a control group or to one of two experimental groups. The control group ate a low P/S ratio diet for 12 wk while the first experimental group ate a high P/S ratio diet for 6 wk followed by a low P/S ratio diet for the next 6 wk. The second experimental group ate a low P/S ratio diet in the first 6 wk followed by a high P/S ratio diet for the next 6 wk. Dietary P/S ratio, plasma linoleic acid (18:2), and cheek cell phospholipid 18:2 levels were compared in each dietary group at the end of the 1st and 2nd 6 wk. On change from a low to a high P/S ratio diet, there was a 36% increase in the proportion of 18:2 in the cheek cell phospholipids in comparison with the proportion existing before the change. This was associated with an increase in the proportion of 18:2 in the plasma lipids of this group. No reduction in the proportion of 18:2 in the cheek cell phospholipids was apparent in the control group or the group which changed from a high to a low P/S ratio diet, although in the latter group there was a reduction in the proportion of 18:2 in the plasma lipids. As the phospholipid fatty acid composition of human cheek cells reflects dietary lipid status under certain conditions, this observation may be useful in dietary and nutritional studies, particularly as human cheek cells can be obtained in a noninvasive manner.
The determinants of actinic skin damage: problems of confounding among environmental and constitutional variables.
Constitutional and environmental determinants of actinic skin damage, assessed by cutaneous microtopography, were evaluated in 1,216 subjects attending the 1981 Busselton Health Survey in Western Australia. Increasing age, male sex, the tendency to burn on exposure to sunlight and outdoor occupation were found to have independent predictive value for the presence of actinic skin damage. Crude positive and inverse associations of actinic skin damage with several other factors were shown to arise from confounding. Effect measures for outdoor leisure pursuits and sunscreen use were underestimated due to inverse associations of these factors with older age, and inverse associations of high-exposure outdoor activities with poor skin response to sunlight. Associations of constitutional traits typical of fair individuals and sunscreen use with the tendency to burn resulted in overestimation of effect measures. Empirical relationships of actinic skin damage with certain leisure activities and with use of sunscreens were also confounded by sex. The results indicate a need for greater attention to confounding in nonexperimental skin cancer research.
Relationship of solar keratosis and history of skin cancer to objective measures of actinic skin damage.
Two methods for the assessment of severity of actinic skin damage were evaluated in a population-based survey of 1216 subjects. After controlling for the effects of age, skin texture changes graded by cutaneous microtopography were found to be associated strongly with the presence of solar keratoses and a past history of non-melanotic skin cancer. Changes in skin condition graded by paraocular photography had a weaker relationship with the presence of keratoses and showed no association with non-melanotic skin cancer. These results, together with a higher level of agreement between observers in grading cutaneous microtopographs, support the use of cutaneous microtopography as an index of actinic skin damage in epidemiological research.
Trends in ischemic heart disease mortality and morbidity in Perth Statistical Division.
Trends in mortality from Ischemic Heart Disease (IHD) and other principal causes of death, and in hospital admission rates for Acute Myocardial Infarction (AMI) have been studied in residents aged 35-64 years of the Perth Statistical Division for the period 1968-1982. Death rates were based on data abstracted from official statistics or computer tapes of unit death records. Hospital admission rates were derived from the computer tapes of the Western Australian Hospital Inpatient Survey, 1968-1982. Since 1968, mortality from IHD has fallen in the Perth Statistical Division in both males and females by 30% and 33%, respectively. This fall has occurred principally in deaths occurring out-of-hospital and has been accompanied by similar falls in mortality from other vascular diseases and in total mortality. Hospital admission rates for Acute Myocardial Infarction (AMI) in the Perth Statistical Division have fallen since 1971 by 17% in males and 27% in females. These findings taken together suggest that the improvement in IHD mortality in Western Australia has been due mainly to a fall in the incidence of acute manifestations of IHD (sudden death and AMI), rather than improvements in case fatality. The possible underlying mechanisms responsible for this are discussed.
The fall in mortality from ischemic heart disease in Australia: has survival after myocardial infarction improved?
Trends in mortality and survival after myocardial infarction (MI) were studied by use of computerised death and hospital discharge records for 25 to 64 year old residents of the Perth Statistical Division between 1971 and 1979. Highly significant falls in ischemic heart disease (IHD) mortality rates were found for men (18%) and women (29%) but 4, 26 and 52 week survival after hospital admission for MI remained constant at around 88%, 84% and 81% respectively. Further, as 75% of all IHD deaths between 1971 and 1979 occurred before the victim was admitted to hospital, the survival of those receiving treatment would have had to be greatly improved to influence total mortality from IHD appreciably. As the age and sex composition of persons hospitalised for MI and the proportion of MI victims hospitalised did not change during the study period it would seem that improved survival after hospital admission for MI did not contribute to the fall in IHD deaths between 1971 and 1979.
Vegetarian diet, blood pressure and cardiovascular risk.
This paper reviews the association between a vegetarian diet and a number of risk factors for cardiovascular disease investigated in a series of epidemiological and experimental studies. Ninety-eight Seventh-day Adventist "vegetarians" were similar to 113 Mormon omnivores for strength of religious affiliation, consumption of alcohol, tea and coffee and use of tobacco, but were significantly less obese and had significantly lower blood pressures adjusted for age, height and weight. A random sample of forty-seven Adventist vegetarians had significantly lower home blood pressures, serum cholesterol levels and blood pressure responses to a cold-pressor test than Mormon omnivores carefully matched for age, sex and Quetelet's index. In a controlled dietary intervention study mean systolic and diastolic blood pressures and serum cholesterol fell significantly during feeding with a vegetarian diet--an effect unrelated to changes in other lifestyle factors. Dietary analysis indicated that a vegetarian diet provided more polyunsaturated fat, fibre, vitamin C, vitamin E, magnesium, calcium and potassium and significantly less total fat, saturated fat and cholesterol than an omnivore diet. There was no evidence for a difference between vegetarians and omnivores in levels of catecholamines, plasma renin activity, angiotensin II, cortisol or serum and urinary prostanoids.
Dietary fats and blood pressure.
The blood pressure lowering effect of elevating the dietary polyunsaturated/saturated (P/S) ratio has been assessed in a randomised, controlled trial in normotensive volunteers. Subjects were allocated either to a control group who ate a low P/S ratio diet throughout, or to one of two experimental groups who ate a high P/S ratio diet for one of two six week experimental periods. There were significant changes in estimated dietary P/S ratio and measured changes in plasma fatty acids and buccal mucosal cell phospholipids. Changes in blood pressure were not related to changes in P/S ratio. There were no changes in other factors which may have confounded the relationship between blood pressure and P/S ratio change. This study suggests that P/S ratio change, without changing other nutrients, does not affect blood pressure in normotensive subjects.
Alcohol and hypertension.
The nature of the association between alcohol consumption and blood pressure has been studied in 491 working men in Western Australia. The effect of alcohol on systolic blood pressure was seen to be independent of obesity, age, cigarette smoking, coffee or tea consumption, educational attainment or personality type. Ex-heavy drinkers had similar blood pressures to teetotallers. Men drinking the equivalent of three or more glasses of beer a day had a 10.4% prevalence of hypertension compared with 2.6% in teetotallers while the most introverted tertile of non-smoking drinkers had a 22% prevalence of hypertension. Possible mechanisms by which repeated alcohol ingestion might lead to hypertension are discussed in the light of hemodynamic and biochemical studies in pairs of drinkers and teetotallers.
Autoimmune thyroid disease and giant cell arteritis: a review, case report and epidemiological study.
A 75-year-old man with the simultaneous onset of Graves' disease and giant cell arteritis is described. Although there have been few previous reports of simultaneous onset, literature review and a retrospective study of the records of this hospital suggest that the association of Graves' disease and the polymyalgia rheumatica-giant cell arteritis syndrome is not simple coincidence. The patient's course was complicated by cerebral infarction secondary to either arterial thrombo-embolism or arteritis.
"Give it away for a day": an evaluation of Western Australia's first smoke free day.
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Mortality of fire fighters in Western Australia.
All except 17 (1.7%) of 990 fire fighters employed by the Western Australian Fire Brigade between 1 October 1939 and 31 December 1978 were successfully followed up to 31 December 1978. Mortality from all causes was less than expected (SMR 0.80 with 95% confidence interval 0.67 to 0.96). There was evidence of the healthy worker effect but none that mortality increased with increasing duration of employment. A small proportional excess of deaths from road traffic accidents ( SPMR 1.66) appeared to be unrelated to fire service. Deaths from other accidents, poisonings, and violence were significantly less than expected (SMR 0.35 with 95% confidence interval 0.10 to 0.90) and may indicate an effect of training and experience on accident proneness. There was no evidence of increased mortality from cardiovascular or respiratory disease, or from any other cause.
Dietary fat intake and blood pressure: a double blind controlled trial of changing polyunsaturated to saturated fat ratio.
The effect on blood pressure of elevating the dietary polyunsaturated/saturated fat (P/S) ratio was assessed in a double-blind, randomized control trial. Fifty-four healthy, normotensive volunteers aged between 20 and 59 years were randomly allocated either to a control group who ate a low P/S ratio diet throughout, or to one of two experimental groups who ate a high P/S ratio diet for one of two six-week experimental periods. Other nutrient changes were avoided. Twenty-four-hour diet records showed substantial changes in the P/S ratio when on the high P/S ratio diet, and no change in the control group or either experimental group when on the low P/S ratio diet. Relative concentrations of linoleic acid in plasma and cheek cell phospholipids were significantly increased when on the high P/S ratio diet. Changes in blood pressure, before and after adjustment for other possible confounding factors, were not related to changes in P/S ratio. It was concluded that an increase in P/S ratio per se cannot account for the previously reported blood pressure lowering effect of a vegetarian diet.
Pigmentary traits, ethnic origin, benign nevi, and family history as risk factors for cutaneous malignant melanoma.
The roles of constitutional factors and benign nevi in causation of malignant melanoma were examined in a case-control study of 511 patients and 511 matched controls in Western Australia. The strongest risk factor was the number of palpable benign nevi on a subject's arms. Compared to the risk of melanomas for persons having no palpable nevi on the arms, the relative risk of melanoma was 2.0 for persons with 1-4 nevi, 4.0 for persons with 5-9 nevi, and 11.3 for persons with 10 or more nevi (P less than .0001). Of the several pigmentary traits known to have associations with melanoma, inability to tan was the most important. Susceptibility to sunburn and hair color also had significant effects that were independent of tanning ability; however, after these traits were controlled, measured skin color and eye color had no additional effects. A reduced risk of melanoma was observed in persons having two or more Southern European grandparents [odds ratio (OR) = 0.39; P = .025]. Persons of Celtic origin did not have a significantly increased risk (OR = 1.18). Possession of one or more affected blood relatives was related to an increased risk of melanoma (OR = 2.69; P less than .0001). The effects of pigmentary traits, benign nevi, ethnic origin, and family history as risk factors were largely independent of one another.
Cutaneous malignant melanoma and indicators of total accumulated exposure to the sun: an analysis separating histogenetic types.
Evidence associating malignant melanoma with semiquantitative and questionnaire indicators of past sunlight exposure is presented from a case-control study of 511 patients and 511 matched control subjects in Western Australia. That melanoma is related to sun exposure was supported by associations with actinic skin damage graded by cutaneous microtopography, history of nonmelanotic skin cancer, duration of residence of migrants to Australia, and mean annual hours of bright sunshine received at locations where the subjects had resided. Separate analyses of histogenetic subtypes revealed that Hutchinson's melanotic freckle melanoma had the strongest associations with indicators of sunlight exposure. For superficial spreading melanoma, a specific relationship was observed with age at arrival as against duration of residence in Australia. Migrants arriving before age 10 years appeared to have a risk similar to that of native-born Australians, whereas the estimated incidence in those arriving after age 15 years was around one-quarter of the native-born rate, with arrival at later ages giving no additional advantage. Control subjects arriving in Australia before age 10 years had an increased number of nevi on their arms, suggesting that sun exposure in early life may be a factor in nevus production and, therefore, a determinant of later potential to develop superficial spreading melanoma.
Possible infectious etiology of six cases of Ewing's sarcoma in Western Australia.
Six cases of Ewing's sarcoma occurring in Western Australia during a 2-year period are reported. All six patients lived in rural habitats and reported exposure to farm animals. There was evidence of direct contact between two patients over a 3-year period preceding the diagnosis of their tumors. These features raise the possibility that Ewing's sarcoma has an infectious etiology.