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Biomedical subjects

A B Miller

Publications and source records attributed to A B Miller.

At least 271 records · Page 15Linked to original sources
PubMed1984

Esophageal compression of the heart presenting as an extracardiac mass on echocardiography.

Echocardiography is helpful in the identification of extracardiac masses. The role of echocardiography in evaluating the effects of the masses on the heart is not well established. The case presented details the identification of and the evaluation by echocardiography of structural and functional effects of a massively dilated esophagus on the heart. Two-dimensional echocardiography revealed anatomic distortion due to a mass effect of the dilated esophagus on the left heart chambers. M-mode echo recordings demonstrated decreased left atrial and ventricular dimensions with increased atrial and ventricular fractional shortening. These findings normalized after Heller myotomy, without a change of estimated stroke volume.

Adult↗
PubMed1984

Epidemiological assessment of risk to humans from exposure to nitrosamines.

In order for epidemiologists to evaluate the 'nitrosamine hypothesis' it is necessary to develop measures of human exposure to N-nitrosamines - both exogenous and when formed internally through consumption precursors. Dissatisfied with indefinite findings using indirect indices of N-nitrosamine exposure, we have attempted to derive an index based on the known kinetics of N-nitrosamine formation. This has been applied in a case-control study of cerebral tumours and resulted in a suggestive finding of increased risk for exogenous but not total N-nitrosamine exposure. A potential difficulty with our index is doubt as to whether vegetable sources of nitrates and consequent endogenous formation of nitrites indeed result in N-nitrosamine exposure, in view of the possible presence of blocking agents or of vitamin C consumed at the same time as vegetables. Further work is necessary, but we hope to apply the index in a case-control study of gastric cancer currently under analysis.

Dimethylnitrosamine↗
PubMed1983

Food items and food groups as risk factors in a case-control study of diet and colo-rectal cancer.

The contributions of food items and food groups as risk factors in a previously reported case-control study of diet and colo-rectal cancer have been analyzed. The study included 348 patients with colon cancer, 194 with rectal cancer, 542 neighbourhood controls individually matched to the cases on the basis of age and sex and a second control series of 535 surgical hospital controls frequency matched to the cases. For colon cancer, as in the previous analysis, the major risk factor was saturated fat, individual food items or groups failing to make a significant contribution to the risk. In particular there was no protective effect of dietary fibre and, for cruciferous vegetables, only a minor protective effect in females. No individual cruciferous vegetable made an important contribution to this effect. For rectal cancer, on the other hand, a significant effect of saturated fat, independent of other food items or groups, was only found for females in the highest consumption category. For males, consumption of eggs, beef and veal significantly increased risk but not consumption of pork, while for females, there was a non-significant increase in risk with consumption of eggs, no increased risk with consumption of beef or veal and a significantly increased risk with consumption of pork. There was no protective effect of dietary fibre or of cruciferous vegetables for rectal cancer, but in females, there was a significantly increased risk for consumption of beer, though this was somewhat reduced when controlled for consumption of saturated fat. There was no indication of an effect of alcohol in either sex or of beer in males. Thus, these results confirm the previous report in showing a significant effect of saturated fat in increasing risk of colon cancer but suggest a contribution of meats to risk of rectal cancer.

Canada↗
PubMed1983

Trends in cancer mortality and epidemiology.

The increase in lung cancer in men has ceased at younger ages and is slowing at older ages. However, in women the increase continues and, by the end of this decade, lung cancer may be the most important cause of cancer deaths in women. The incidence of prostate and breast cancer continues to increase, but mortality is stable, suggesting changes in diagnostic practices. Mortality from stomach cancer and from cancer of the cervix in women continues to fall. Increasingly, it is necessary to recognize the multifactorial causes of cancer, requiring detailed information on lifestyle, occupational, and sometimes residential histories to unravel etiology. Physicians need to understand the requirement for access to patients in order to obtain data for studies. Monitoring unexpected hazards will require linkage, particularly using the National Death Index. Such sources can be used with preservation of confidentiality while increasing knowledge for primary prevention.

Breast Neoplasms↗
PubMed1983

Screening for breast cancer.

Screening for breast cancer using the combination of physical examination of the breasts and mammography was effective in women age 50 or more in the HIP study. However, major questions remain, especially the benefit of screening women age 40-49, and the independent effect of mammography. Such questions can only be answered by large-scale randomized controlled trials, and trials to answer these questions are now underway in Canada (the NBSS) and Sweden. Only the NBSS, however, is attempting to replicate the HIP study in women age 40-49, and to evaluate the additional contribution of mammography to annual physical examination in women age 50-59. The Swedish studies are evaluating the effectiveness of mammography alone, while studies in Britain will help to evaluate breast self-examination (BSE) and biannual mammography with annual physical examination. Because much of the benefit in HIP could have derived from the physical examination, it is necessary to complete the present trials before population-based screening for breast cancer using mammography can be advocated. Trials are justifiable because the risk of mammographic screening seems likely to be negligible, and the use of the combination of annual mammography and physical examination to be cost-effective. In the meantime, there seems no immediate substitute on a population basis for efficient physical examination of the breasts by primary care physicians coupled with breast self-examination by the woman. Techniques such as ultrasound and diaphanography seem unlikely to supplant mammography in screening, and in any case, have to be evaluated in comparison with mammography.

Adult↗
PubMed1983

Left ventricular function and extent of coronary artery disease in the absence of antecedent myocardial infarction in patients with ischemic cardiac pain.

Left ventricular (LV) function and extent of coronary artery disease (CAD) are important prognostic factors in patients with ischemic cardiac pain (ICP). This study was designed to compare LV function in patients with ICP admitted to our coronary care unit (CCU). Patients with previous transmural myocardial infarction (TMI) or who were over age 75 were excluded. Group 1 (n = 17) developed their 1st TMI; group 2 (n = 14) were diagnosed as unstable angina (UA). All patients demonstrated significant CAD on arteriography; i.e., at least 70% stenosis of at least 1 major coronary vessel. LV function was evaluated by single plane ejection fraction (EF), end-diastolic volume index (EDVI) (ml/m2), and the slope of a modified LV function curve (S) utilizing change in CI divided by change in end-diastolic pressure at rest and post-LV angio (ml X min X M-2 X mm Hg) (normal +/- SD: 176 +/- 39). Both TMI and UA patients had LV dysfunction; although group 1 had more severe abnormalities, they were not statistically significant. Eleven (65%) in group 1 and 10 (71%) of 14 in group 2 had multivessel CAD. We conclude that in patients without previous TMI admitted with ICP: (1) Those who do not develop TMI have similar LV dysfunction compared to those with TMI; and (2) TMI and UA patients have similar multivessel CAD.

Aged↗
PubMed1982

Risk factors from geographic epidemiology for gastrointestinal cancer.

The incidence of gastrointestinal cancers differ greatly internationally. Blacks have higher rates than whites for esophagus, stomach, liver, and pancreatic cancer in the U.S. Differences also occur between other racial groups. Studies on migrants suggest environmental causes for these differences. Stomach cancer rates have fallen, intestine cancer is stable, pancreatic cancer rates rose, but are now falling in males. The incidence of colon, rectal, breast, corpus-uterus, ovary, and prostate cancer are positively correlated, but colon or rectal and stomach cancer are negatively correlated. Colon and rectal cancer mortality are positively and stomach cancer negatively associated with social class. Esophageal, liver, colon, and pancreatic cancer in males are higher in urban areas. Seventh Day Adventists and Mormons show a low risk of colon cancer. Internationally intake of fat is correlated with colon, rectal, and pancreatic cancer, and starch with stomach cancer.

Demography↗
PubMed1982

Evaluation of a self-administered dietary questionnaire for use in a cohort study.

A self-administered diet questionnaire designed for use in a cohort study has been assessed in comparison with a detailed quantitative diet history previously used in and validated for case-control studies. One hundred fifty-eight women aged 40 to 59 were asked to complete the self-administered questionnaire and 123 returned it by mail. Of these women, 50 were interviewed at home using the detailed diet history. Estimates of intake of major nutrients other than fat and fatty acids are comparable from the two methods although in general, estimated intake from the self-administered questionnaire was higher than the diet history. The difference in intake of fat and fatty acids was largely but not completely accounted for by differences in amounts of added fat recorded. It is concluded that when applied to large numbers of women in a cohort study, the self-administered questionnaire is feasible to administer and will be sufficiently accurate in estimating nutrient intake as compared to estimates from a detailed, interview-type diet history.

Adult↗
PubMed1982

Optimising the age, number of tests, and test interval for cervical screening in Canada.

Different approaches to screening for cancer of the cervix by cervical cytology have been evaluated using a computer simulation model developed by Knox and data on the natural history of carcinoma-in-situ (or worse) from a cohort study of women screened in British Columbia, 1949-69. The natural history input parameters and the output parameters without screening were modified to reflect the earlier onset of carcinoma-in-situ in younger cohorts now being experienced in British Columbia, resulting in simulated mortality from carcinoma of the cervix approximately 50% greater than that experienced in Canada in 1955. The simulations showed that the sensitivity of the test and the proportion of women in the population who accept invitations to attend for screening materially influence the extent to which programmes reduce mortality. Missed screens also have an important impact. With a 75% test sensitivity, and an 80% population acceptance, a programme designed to reduce mortality by 90% would commence at age 25, involve triennial screens to age 52, or triennial screens to age 40 and quinquennial screens to age 60, a total of 10 tests in a lifetime. A repeat test at age 26 contributes nothing to the mortality benefit. Nevertheless, additional modifications of the natural history specifications to accommodate high-risk younger women would require a more frequent schedule of examinations under the age of 35, though at a substantial 'cost' in terms of the total number of examinations required in a population.

Adolescent↗
PubMed1982

Nutritional aspects of human carcinogenesis.

Evidence that nutritional factors are involved in human carcinogenesis has come from studies of migrants, correlational studies of various dietary factors with incidence and mortality, internationally and nationally, associations with host factors which may be nutritionally mediated, and case-control studies in various populations. For breast cancer, migrant studies suggest that dietary factors may operate in early life; correlational studies show strong associations with total fat intake; associated host factors include age at menarche and height and weight; and two case-control studies have suggested an association with total fat intake. For colorectal cancer, migrant studies suggest that dietary factors can operate later in life; correlational studies have shown associations with total fat, total protein, beef and certain fibre fractions; associated host factors include serum cholesterol and intestinal excretion of bile acids and salts; and case-control studies have shown the importance of western type meals and beef intake in Hawaiian Japanese (although this was not replicated in Japan), a protective effect of fibre in Israel, a protective effect of cruciferous vegetables in the United States and an association with saturated fat intake but not with crude fibre intake in Canada.

Body Weight↗
PubMed1982

Observer variation in the interpretation of xeromammograms.

We have examined variation in the interpretation of xeromammograms among radiologists designated to take part in a Canadian multicenter randomized controlled trial of screening for breast cancer. Radiologists read 100 xeromammograms comprising 10 histologically proved cancers, 40 benign abnormalities, and 50 normal films. Radiologists' opinions differed widely on the frequency of suspected or identified cancer. The diagnostic category "suspicion of cancer" or "cancer" was selected by radiologists for 10-55% of the films, and biopsy or aspiration was recommended for 21 to 53% of patients whose films were examined. Agreement on specific diagnostic categories was greatest for the diagnosis of cancer; agreement was least for the diagnosis of benign abnormalities and intermediate for the diagnosis of normality. Known cancers were in general correctly identified. These results indicate a need for development of methods to reduce observer variation in a interpretation of xeromammograms while preserving diagnostic sensitivity and validity. Results also emphasize the importance of developing strategies to ensure quality control in multicenter trials.

Breast Neoplasms↗
PubMed1982

Breast cancer mortality following fluoroscopic irradiation in a cohort of tuberculosis patients.

A study has been conducted to determine the mortality experience from 1950-1977 of a cohort of women treated for tuberculosis in Canadian sanatoria between 1930 and 1952. Approximately 50 percent of these women received substantial breast tissue doses of fluoroscopic irradiation in conjunction with their treatment by artificial pneumothorax. A preliminary analysis of 23572 women known alive at the beginning of 1950 has shown a highly significant breast cancer mortality risk for those women exposed to such radiation. There is evidence of decreasing effect with increasing age at first exposure, and no increase in risk is observed until ten years after first exposure.

Breast Neoplasms↗
PubMed1982

Dietary factors in relation to the etiology of colorectal cancer.

A case control study of 542 cases of colorectal cancer, 542 neighborhood controls, and 535 hospital controls has been conducted in two areas of Canada. The consumption of 13 nutrients has been estimated individually for all study members using an extensive diet history questionnaire. Highly significant dose-response relationships are observed between saturated fat intake and increased risk of both colon and rectal cancer for both sexes. In contrast no increase in risk was observed for intake of any level of polyunsaturated fat. The data are thus supportive of the hypothesis that dietary saturated fats may be of etiologic significance in cancers of the large bowel.

Colonic Neoplasms↗