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Biomedical subjects

B K Armstrong

Publications and source records attributed to B K Armstrong.

At least 109 records · Page 6Linked to original sources
PubMed1987

Cervical cancer mortality trends in Australia--an update.

Trends in the mortality rate due to cancer of the cervix in Australian women were reviewed for the period 1950-1984, taking into account the changes in the proportion of women who have undergone a hysterectomy. Cohort-based increases in women who were born after 1935, which had been reported previously, were observed to extend into the 40 to 44 years' age group and to continue the upward trend in women aged 30-39 years. However, for women who were less than 30 years of age there was evidence of a recent fall in the rate of cervical cancer mortality.

Adult↗
PubMed1987

Size-dependent blood-brain barrier opening demonstrated with [14C]sucrose and a 200,000-Da [3H]dextran.

The reclosure of the blood-brain barrier following osmotic opening was investigated by determining the product of permeability times surface area for two neutral, water-soluble compounds differing widely in molecular size. [14C]Sucrose (Mr 340 Da, radius 5A) and [3H]dextran (Mr 200,000 Da, radius 100 A) were simultaneously injected i.v., and their regional permeability times surface areas were calculated at 6, 10, 35, and 55 min after the blood-brain barrier was opened by a 30-s infusion of 1.8 m L(+)-arabinose into the right external carotid artery. The control permeability times surface area product was about 10(-5) cm3 s-1 g-1 brain for sucrose and negligible for dextran. It increased to 4 X 10(-4) cm3 s-1 g-1 brain and 10(-4) cm3 s-1 g-1 brain for sucrose and dextran, respectively, at 6 min after opening of the blood-brain barrier. Thereafter, permeability-surface area products for both substances declined. Dextran had significantly lower (P less than 0.05) values than sucrose at all times. The ratios of permeability times surface areas of [14C]sucrose to those to [3H]dextran were consistent with restricted diffusion through pores or slits at 35 and 55 min after blood-brain barrier opening, but at 6 and 10 min these ratios were less than the ratio of their free diffusion coefficients, indicative of bulk fluid flow with solute drag from blood to brain. A previously measured increase in brain water content following opening of the blood-brain barrier together with the present results, suggest the creation of slits approximately 400 A in width after osmotic treatment. Reduction in bulk fluid flow from blood to brain appears to be the major cause for the reduction of permeability times surface areas for both sucrose and dextran as the blood-brain barrier recloses.

Animals↗
PubMed1987

Identification of non-fatal myocardial infarction through hospital discharge data in Western Australia.

The validity of identifying incident cases of non-fatal acute myocardial infarction (AMI) between 1971 and 1982 in Western Australia from routine hospital records was assessed in ages 25-64 years, according to the WHO criteria defined in 1970 and 1983. This was done by reviewing original data sources and by using the Perth Coronary Register of 1971 as an external reference. Events with a coded discharge diagnosis of acute or subacute ischemic heart disease were found to be highly sensitive (97%) for cases of "definite" AMI (WHO 1983 criteria). The specificity of such events was lower (positive predictive value of about 70%) and validation of these events would be necessary for studies requiring high specificity. The sensitivity and specificity of these events for "definite" AMI seemed quite stable over time with similar values being observed in 1971 and 1978. Although the situation for "possible" AMI (non-fatal) is less clear, certainly many more records would need to be reviewed to validate this diagnosis.

Adult↗
PubMed1987

Estimation of myocardial infarction mortality from routinely collected data in Western Australia.

The accuracy of routinely collected mortality data for ischemic heart disease (IHD) as indicators of death from acute myocardial infarction (AMI) was assessed in ages 25-64 years, according to the WHO criteria defined in 1983. Cases were identified from computer records (linked for individuals) of all death certificates and hospital discharges in Western Australia between 1971 and 1982. Where the official cause was IHD about 90% of deaths fulfilled the WHO criteria for definite or possible AMI. Up to 10% of fatal cases of definite or possible AMI were coded to other causes in the official death statistics, however it appeared that variations in this figure with changes in coding practices could cause appreciable bias in the estimation of secular trends in IHD mortality. This problem could largely be overcome by reviewing fatal events where the death certificate was coded to one of a limited number of other ICD rubrics.

Adult↗
PubMed1987

A randomized controlled trial of the effect of dietary fibre on blood pressure.

Eighty-eight healthy omnivores with normal blood pressure participated in a randomized, controlled, cross-over trial of the effect on blood pressure of increasing dietary fibre intake. Subjects were randomly allocated to a control group eating a low fibre diet throughout, or to one of two experimental groups eating a high fibre diet for one of two 6-week experimental periods. Changes in body weight, other dietary constituents and lifestyle factors were avoided as far as possible. Twenty-four hour diet records showed a substantial increase in dietary fibre when subjects were on the high fibre diet. There was no consistent effect of change in dietary fibre intake on group mean systoloic or diastolic blood pressures. Adjusting blood pressures for changes in other dietary components, plasma lipids, electrolytes, body weight and other lifestyle variables did not alter this result. These findings do not support the hypothesis that the blood pressure lowering effect of a vegetarian diet is solely due to an increase in fibre intake.

Adult↗
PubMed1987

Second cancers in patients with chronic lymphocytic leukemia.

Among 419 persons diagnosed as having chronic lymphocytic leukemia (CLL) in western Washington State between 1974 and 1983 and followed through January 1985, 9 subsequently developed other lymphoid cancers and 48 developed nonlymphoid cancers. Only 2 lymphoid and 21 nonlymphoid cancers were expected based on the rates of the western Washington population as a whole. Lung cancer accounted for about one-third of the excess rate observed. Three of the nonlymphoid tumors that occurred in the patients with CLL were classified as malignant fibrous histiocytomas, which represents an exceptionally high relative incidence for this histologic type. The excess risk of nonlymphoid cancers was present in both sexes, across all age categories, and in every length-of-follow-up interval. These results, taken together with those obtained from earlier investigations, suggest that persons with CLL are at increased risk of developing a second tumor, particularly in the lung. The reasons for this increased risk remain to be elucidated.

Adult↗
PubMed1987

Seasonal variation in the incidence of cutaneous malignant melanoma: an analysis by body site and histologic type.

A seasonal analysis of the incidence of cutaneous malignant melanoma was conducted to investigate the degree to which the increased frequency of cases diagnosed in the summer may be due to an artifact of increased ascertainment. The monthly incidence of 13,151 microscopically-confirmed cases of cutaneous malignant melanoma diagnosed between 1973 and 1982 among white residents of nine regions in the United States served by population-based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program was evaluated for the presence of seasonal trends. Except for nodular melanoma, there was substantial seasonal variation in the incidence of all histologic types. For the two most common categories, superficial spreading melanoma and melanoma not further classified as to histology (of which the majority are likely to be superficial spreading melanoma), the peaks in incidence at body sites which are likely to experience seasonal changes in clothing (upper limbs, trunk, legs) occurred in the summer and were of similar relative size to the peaks, located in the spring, at sites which are likely to experience little variation in clothing during the year (head, face, and neck). A summer peak was also observed for Hutchinson's melanotic freckle melanoma of the head, face, and neck. The presence of seasonal variation in the incidence of superficial spreading melanoma of the head, face, and neck suggests that increased ascertainment cannot by itself account for seasonal variation in the incidence of superficial spreading melanoma of other parts of the body.

Female↗
PubMed1987

Vegetarian diet and blood pressure.

There is now convincing evidence from epidemiological studies and randomized controlled trials that adoption of an ovo-lacto vegetarian diet leads to blood pressure reduction in both normotensive and hypertensive subjects. This effect appears to be independent of both dietary sodium and weight loss but additive to effects of weight reduction. Long-term adherence to a vegetarian diet is associated with less of a rise of blood pressure with age and a decreased prevalence of hypertension. The nutrients responsible for these effects have not been clearly identified and the mechanisms involved are unknown. Resolution of these questions is needed to enable more widespread adoption of dietary changes which may reduce the prevalence of hypertension, reduce antihypertensive drug dependence and by effects on blood pressure and blood lipids ameliorate the natural history of hypertensive cardiovascular disease.

Blood Pressure↗
PubMed1987

Melanoma in Western Australia in 1980-81: incidence and characteristics of histological types.

All cutaneous malignant melanomas diagnosed in Western Australia in 1980-81 were reviewed and classified according to histological type (i.e., superficial spreading melanoma, Hutchinson's melanotic freckle melanoma (lentigo maligna melanoma), nodular melanoma and melanoma of unclassifiable type). The most common invasive melanoma was superficial spreading melanoma with an incidence rate of 14.3 per 100,000 person-years in females and 9.0 in males. It most commonly affected the trunk in males and the lower limbs in females and showed a peak incidence in middle life. Invasive Hutchinson's melanotic freckle melanoma was much less common than invasive superficial spreading melanoma (1.8 per 100,000 person-years in both sexes), occurred most commonly on the head and neck and increased progressively in incidence with age. Nodular melanomas were more frequent in men (4.5 per 100,000 person-years) than women (2.0). They were thicker than other types of invasive melanomas, showed more mitotic activity and had less evidence of regression. Their site distribution was similar to that of superficial spreading melanoma. In women the pattern of incidence with age was also similar to that of superficial spreading melanoma. In men it was more like that of Hutchinson's melanotic freckle melanoma. Melanomas of unclassifiable type did not have distinctive epidemiological features common to both sexes, although the trunk was the site most commonly affected in both men and women. With some exceptions the patterns of occurrence of in-situ lesions were similar to those of the corresponding invasive lesions. Benign melanocytic naevi were found less often in association with Hutchinson's melanotic freckle (melanoma) (6%) and nodular melanoma (9%) than with superficial spreading melanoma (22%) or melanoma of unclassifiable type (34%).

Adolescent↗
PubMed1987

Malignant melanoma of the skin.

Ultra-violet radiation (UVR) in sunlight is thought to be the main cause of malignant melanoma in lightly-pigmented populations. Individuals with fair skin, fair hair, blue eyes and/or a tendency to burn rather than tan when exposed to the sun are at particularly high risk of melanoma and should be given special attention in primary prevention programmes. Intermittent exposure to the sun, as in recreational exposure, may be a more potent cause of melanoma than more continuous exposure. Primary prevention offers the best prospects for a substantial reduction in mortality from malignant melanoma. However, there is little evidence available to judge the effectiveness of primary prevention of melanoma through reduction of exposure to the sun. Education for reducing exposure to the sun is common in high-risk populations but has never been evaluated adequately. Mortality from melanoma could also possibly be reduced by earlier diagnosis through education or screening of high-risk groups. Regular screening of patients with the familial dysplastic naevus syndrome should reduce their mortality from melanoma.

Humans↗
PubMed1987

Environmental temperature and blood pressure in 9-year-old Australian children.

Relationships between blood pressure (BP) and environmental temperature were investigated as part of a broader study of constitutional and environmental determinants of BP in a sample of 1037 9-year-old Australian children. A Dinamap semi-automatic device was used to obtain three BP readings for each child. Average systolic blood pressure (SBP) and diastolic blood pressure (DBP) differed according to month of examination, with higher levels in the colder months. Negative relationships were observed between BP and temperature on the measurement day; computed regression equations indicated that a rise in maximum daily temperature of 10 degrees C was associated with falls of 5-7 mmHg in SBP and DBP. The relationships were independent of age, weight, height, socio-economic status and heart rate (HR). The results emphasize the importance of taking environmental temperatures into account in epidemiological studies of BP.

Anthropometry↗
PubMed1986

Vegetarian diet in mild hypertension: a randomised controlled trial.

In a randomised crossover trial 58 subjects aged 30-64 with mild untreated hypertension were allocated either to a control group eating a typical omnivorous diet or to one of two groups eating an ovolactovegetarian diet for one of two six week periods. A fall in systolic blood pressure of the order of 5 mm Hg occurred during the vegetarian diet periods, with a corresponding rise on resuming a meat diet. The main nutrient changes with the vegetarian diet included an increase in the ratio of polyunsaturated to saturated fats and intake of fibre, calcium, and magnesium and a decrease in the intake of protein and vitamin B12. There were no consistent changes in urinary sodium or potassium excretion or body weight. In untreated subjects with mild hypertension, changing to a vegetarian diet may bring about a worthwhile fall in systolic blood pressure.

Adult↗
PubMed1986

The dysplastic naevus syndrome in patients with cutaneous malignant melanoma in Western Australia.

One hundred and three patients with cutaneous malignant melanoma responded to an invitation to attend a dermatology outpatient clinic. All patients with a family history of melanoma, a history of multiple melanomas, or histological evidence of a dysplastic naevus that was associated with their melanoma were invited. A random sample of other patients with cutaneous malignant melanoma was also invited to attend. First-degree relatives of patients with the dysplastic naevus syndrome (DNS) were invited for a similar examination. DNS was found in 27% of the patients with a family history of melanoma, multiple melanomas, or histological evidence of a dysplastic naevus in association with their melanoma, and in 6% of the remaining patients who were selected at random. DNS was estimated to be present in 12.8% of 17- to 55-year-old patients with cutaneous malignant melanoma in the Perth region, while familial DNS was present in 4.5%. Patients with melanomas with DNS were more likely to be young men and to have numerous naevi, particularly on the lateral surfaces of the arms, shoulders and trunk, than were patients with melanomas without the syndrome.

Adolescent↗
PubMed1986

Morphology of bronchogenic carcinoma in workers formerly exposed to crocidolite at Wittenoom Gorge in Western Australia.

Cytology and histology material from 46 bronchogenic carcinomas occurring in ex-workers from the Wittenoom crocidolite mine and mill in Western Australia and a matched random sample of 234 other bronchogenic carcinomas occurring in Western Australia over the same period were reviewed by a single histopathologist without knowledge of asbestos exposure status. Squamous-cell carcinomas formed 45.7% of the cancers in the asbestos-exposed group but only 32.5% of the cancers in the comparison group. This difference could not be explained by differences in smoking history between the two groups of lung cancer patients or in the type of histopathological material available for review. The excess of squamous-cell cancers was observed in subjects both with and without parenchymal asbestosis.

Adult↗