Biomedical subjects
B K Armstrong
Publications and source records attributed to B K Armstrong.
Storm in a cup of 2,4,5-T.
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Oral contraceptives and breast cancer.
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Cervical cytology in Western Australia. Frequency, geographical and socioeconomic distributions and providers of the service.
Basic data were obtained from the records of 16,069 women who had smears taken for cervical cytological examination in Western Australia during an eight-week period in 1983. The peak smear rate was 340.7 per 1000 at 25-29 years of age and fell thereafter with age. The estimated peak frequency of smears that were designated as "screening" smears was 178.3 per 1000 at 30-34 years of age. Screening smears comprised 39% to 66% of the total number of smears, depending on age. After correction for the estimated prevalence of past hysterectomy, only in the age range 20-34 years did the rate of all smears approach the rate of screening smears that would be obtained under a recommended frequency of once every three years. The frequency of screening smears was 20% less in rural areas of Western Australia than in the capital city, Perth. In Perth it fell with decreasing socioeconomic status. General practitioners took 62.4% of all smears and 70.3% of screening smears. On average, female general practitioners took twice as many smears than did male general practitioners.
Trends in mortality from malignant mesothelioma of the pleura.
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Melanoma in Western Australia 1975-76 to 1980-81: trends in demographic and pathological characteristics.
Trends in incidence rates of cutaneous malignant melanoma in Western Australia from 1975-76 to 1980-1981 have been examined with reference to age, sex, body site, presence or absence of dermal invasion, tumour thickness, histological type, socioeconomic status and occupation. The incidence rates of all melanomas increased from 22.1 to 31.5 per 100,000 person-years in males and from 23.6 to 28.6 in females. In males, the relative annual increase in the incidence of invasive melanoma was 2.2%, and in females it was 5.6%. In-situ melanomas had larger relative increases in incidence (28% per annum in males and 10% in females) and the thickness of invasive lesions decreased between 1975-76 and 1980-81. The relative increase in incidence of invasive melanomas was greatest on the body sites with the highest rates initially--the trunk in males and the lower limbs in females. There was an increase in the proportion of invasive lesions classified as superficial spreading melanoma. The increase in incidence of in situ melanomas was largely restricted to the head and neck in older men of high socioeconomic status resident in Perth. This trend in in-situ melanoma was mainly due to an increase in the recorded incidence of Hutchinson's melanotic freckle. It may have been, in part, an artefact due to increased recognition of Hutchinson's melanotic freckle in this sub-group of the population.
Multiple myeloma in Western Australia: a case-control study in relation to occupation, father's occupation, socioeconomic status and country of birth.
A death-certificate-based case-control study was undertaken covering 249 patients with multiple myeloma diagnosed in Western Australia from 1975 to 1984 whose deaths were registered in Western Australia in the same period (73.4% of the total diagnosed) and 996 control decedents who were matched to the cases by age, sex and death registration district. Death from multiple myeloma was associated with both farming [odds ratio (OR) 1.44 with 95% confidence interval (CI) 0.81-2.55] and woodworking (OR 1.70 with 95% CI 0.67-4.31) but not with farming as the father's occupation (OR 0.96 with 95% CI 0.66-1.41). It was also more frequent in migrants to Australia than in native-born Australians (OR 1.31 with 95% CI 0.99-1.74) particularly those born in England (OR 1.57 with 95% CI 1.11-2.42) and Italy (OR 2.02 with 95% CI 1.09-3.74). An apparent excess of multiple myeloma in all rural residents appeared to be due to bias introduced by matching for death registration district, as rural residents dying from multiple myeloma were more likely to die and have their deaths registered in the city than other rural residents. A conditional logistic regression analysis showed the above associations to be substantially independent of one another.
The causes of malignant melanoma: results from the West Australian Lions Melanoma Research Project.
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Seasonality of diagnosis of squamous and basal cell skin cancers in Tasmania, Australia.
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Time trends in prevalence of cervical cytological abnormality in women attending a sexually transmitted diseases clinic and their relationship to trends in sexual activity and specific infections.
Trends in prevalence of cytological evidence of cervical intraepithelial neoplasia (CIN) and cervical infection with human papilloma virus (HPV), as indicated by HPV infection and dyskeratosis, were studied in 2,992 new attenders at a sexually transmitted diseases (STD) clinic between 1978 and 1982. Crude prevalence of CIN increased from 1.3% to 4.3% (P less than 0.001) and crude prevalence of HPV infection increased from 2.8% to 9.3% (P less than 0.001). Age adjustment had little effect on these trends. Review, in 1984-85, of samples of smears taken in 1978 and 1982 showed that recognition of koilocytosis by the laboratory had increased substantially over time while a tendency had developed to downgrade nuclear changes in the presence of koilocytosis. Correction of the 1978 and 1982 smear results to the 1984-85 classifications suggested that prevalence of koilocytosis had increased little (from 13.4% to 16.1%, P = 0.20) while there had been a substantial real increase in CIN (0.8% to 2.4%, P less than 0.001). To try to explain the trend in CIN, other characteristics of a sample of attenders at the STD clinic were studied. There were no appreciable trends in prevalence of past STD, number of sexual partners in the last 3 months, method of contraception, genital warts and culture of N. gonorrhoea, T. vaginalis, C. albicans and Chlamydia sp. from the vagina. There was an increase in the proportions in socioeconomic group I, as classified by postcode of residence (17.0% to 26.9%, P = 0.04), referred as contacts rather than with symptoms (24.0% to 41.6%, P less than 0.001), with a clinical diagnosis of genital herpes (5.0% to 8.6%, P = 0.08) and with herpes virus cultured from the cervix (2.1% to 6.3%, P = 0.03). The trend in prevalence of herpes virus infection was not explained by the other trends. It may explain the trend in prevalence of CIN.
Nutrient intake, blood pressure, serum and urinary prostaglandins and serum thromboxane B2 in a controlled trial with a lacto-ovo-vegetarian diet.
Fifty-nine healthy omnivores volunteered for a randomized crossover trial with a lacto-ovo-vegetarian (L-O-V) diet. Twenty-one 1-day diet records were kept throughout the project as a means of assessing food and nutrient intakes, and samples of serum and urine were assayed to evaluate change in prostanoid metabolism. While on the L-O-V diet subjects ate more vegetable protein, wholegrain cereals, polyunsaturated oils, fruits and vegetables, and avoided eating meat, fish or poultry. The L-O-V diet contained significantly more polyunsaturated fatty acids, fibre, vitamin C, vitamin E, magnesium, calcium and potassium, and less total protein, saturated fat, monounsaturated fat and vitamin B12 than the control omnivore diet. Changes in nutrient intakes were subjected to principal components analysis to identify dimensions of change in nutrient intakes. Three Factors accounted for 83% of the total variation in dietary intake. Blood pressure changes were significantly and negatively (F = 17.4, P less than 0.001 for systolic; F = 6.09, P = 0.02 for diastolic pressure) related to individual scores for only one Factor--that representing an increase in intake of polyunsaturated fat, fibre, vitamin C, vitamin E, calcium and magnesium, and a fall in intake of protein and vitamin B12. Blood pressure changes were unrelated to change in body weight or sodium intake. Serum and urinary prostanoids were not affected by eating the L-O-V diet.
A pilot cervical cytology screening service in Perth.
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Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia.
An estimate has been made of the prevalence of unrecognised pneumoconiosis in former crocidolite workers from Wittenoom, Western Australia. All plain chest radiographs relating to a one in six random sample (1025 men) of all former Wittenoom workers who had never entered a compensation claim to the Pneumoconiosis Medical Board of Western Australia were sought from Perth teaching hospitals and from the Perth Chest Clinic where compulsory examination of all workers in the mining industry takes place. Radiographs were recovered for 83% of the men and read independently by two observers. By means of logistic regression analysis a current prevalence of parenchymal abnormality (defined as a radiographic profusion of small opacities of category 1/0 or greater on the ILO classification) of nearly 20% was calculated after adjustment for age, time since first exposure, and cumulative exposure level. One hundred men randomly selected from those known to be alive in the sample were invited to attend for a new radiographic examination. Seventy four men attended and the predicted prevalence was confirmed. It is estimated from these data that there were between 450 and 900 former Wittenoom workers in Australia at the end of 1980 who had radiographic abnormality consistent with pneumoconiosis but had not claimed compensation or had asbestosis diagnosed. The data are consistent with there being no threshold dose of crocidolite exposure for the development of radiographic abnormality in this group.
Relationship of cutaneous malignant melanoma to individual sunlight-exposure habits.
The relationships of different histologic types of cutaneous malignant melanoma to occupational and recreational sunlight exposure, habits of clothing, sunburn histories, and use of sunscreening agents were examined in a case-control study of 507 patients and 507 matched controls in Western Australia. Variations in relationships according to the primary site of melanoma were also examined. An increased incidence rate of superficial spreading melanoma was associated with low total outdoor exposure in early adulthood and frequent participation in boating and fishing. Superficial spreading melanoma of the trunk was also related to frequency of sunbathing at ages 15-24 years and of exposure of the trunk while working outdoors. In women the rate ratio for all types of melanoma occurring on the trunk was estimated at 13.0 (95% confidence interval, 2.0-83.9) in those who wore a bikini or bathed nude at ages 15-24 years compared with those wearing a conservative one-piece bathing suit. There was little evidence that sunbathing or wearing a bikini within 10 years of case diagnosis were risk factors for melanoma of the trunk. After control of confounding due to constitutional factors, only Hutchinson's melanotic freckle melanoma showed a relationship to severe sunburn. For nodular melanoma, sunburn appeared to be protective. Although many of the results supported the hypothesis that melanomas other than the Hutchinson's melanotic freckle type are related to occasional bursts of recreational sun exposure during a susceptible period in early adult life, little support for the hypothesis was obtained when recreational sun exposure was expressed as a proportion of total outdoor exposure, which had been considered a priori to be an index of intermittent sunlight exposure.
Etiology of common acquired melanocytic nevi: constitutional variables, sun exposure, and diet.
Associations were sought between prevalence of nevi on the arms and other variables in controls from a case-control study of cutaneous malignant melanoma. The prevalence of nevi was higher in women than men, fell with age up to about 35 years of age, and was low in those born outside Australia. Among pigmentary characteristics, there was strong evidence only of an association with skin color of the upper inner arm. The highest prevalence of nevi was in those with skin of intermediate darkness. Peak prevalence of nevi was also seen in intermediate categories of variables indicating sun exposure, particularly mean annual hours of bright sunlight at places of residence when 10-24 years of age, total outdoor exposure time per week in the summer at 10-24 years of age, and usual summer suntan on the arms in the last 10 years. These dose-effect patterns may indicate conflicting effects of sun exposure on appearance and disappearance of nevi. The protective effect of birthplace outside Australia appeared to be due to the corresponding low mean annual hours of bright sunlight at places of residence when 10-24 years of age. The prevalence of nevi was comparatively lower in those who drank alcohol and in those who had average or high daily intakes of retinol. These associations were not explained by those of any of the other variables.
Trends in mortality from malignant mesothelioma of the pleura, and production and use of asbestos in Australia.
Annual mortality from malignant mesothelioma of the pleura (MMP) in Australia (as represented by ICD8 codes 163.0 and 212.4, and ICD9 codes 163 and 212.4) increased in men aged 30 years and older from about 0.5/100 000 in 1968-1970 to 2.1/100 000 in 1983. Corresponding rates in women varied from 0.1/100 000 to 0.2/100 000 between 1968 and 1980, then rose to 0.3/100 000 in 1983. The rise in MMP mortality in men probably corresponds to the increasing use of asbestos, particularly amosite, in Australia during and after World War II. That production and importation of amosite and crocidolite in Australia reached a peak in 1958 may mean that peak mortality from MMP will not be reached until the 1990s (allowing a 35-year lag period). Substantial increases in importation and later production, of chrysotile in the 1950s, 1960s and 1970s may lead to increases in the incidence of other asbestos-related cancers, not reflected in trends in the incidence of MMP.
Medulloblastoma: a clinicopathological study of 42 cases.
Clinicopathological data have been collected for 42 patients with cerebellar medulloblastoma diagnosed and treated in Western Australia between the years 1961 and 1984. Thirty-one patients were male and 12 were over 14 years of age. In 31 patients the neoplasms were localized to the midline, while in 10 they were placed laterally in the cerebellar hemispheres. The remaining patient had a diffusely spreading neoplasm in the meninges of the posterior fossa. Thirty-nine underwent surgical treatment followed by postoperative radiotherapy. Three patients died in the early postoperative period. Twenty-four patients survived for one year or longer, 15 for two or more years, 10 for five years, and five survived longer than 10 years. The survival proportions estimated by the life-table method were 66% at one year, 48% at two years and 32% at 5 and 10 years. In one patient who survived for 23 years a meningioma developed, possibly due to radiotherapy.