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Biomedical subjects

A M Stewart

Publications and source records attributed to A M Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1984

Non-cancer effects of exposure to A-bomb radiation.

A slight rearrangement of the data included in a recent report from the Radiation Effects Research Foundation (RERF) has shown differences between cardiovascular and other non-malignant diseases of A-bomb survivors which probably result from two factors: selection effects of early infection deaths and residual effects of marrow damage. Both effects were dose related but neither was obvious becasue one reduced the risk of later infection deaths and the other increased the risk. Allowance for these factors is bound to alter present RERF estimates for cancer effects of radiation and the change will probably be in an upward direction, thus bringing these estimates closer to ones based on radiation workers.

Cardiovascular Diseases↗
PubMed1984

Identification of occupational mortality risks for Hanford workers.

Though most of the production work at Hanford is done by manual workers, 46% of the most dangerous jobs are performed by people who have professional or technical qualifications. For these privileged workers occupational mortality risks are positively correlated with radiation doses but for manual workers, who have relatively high death rates, there is an inverse relation with dose. The high ratio of professional to manual workers is clearly the reason for the industry having fewer observed than expected deaths and the inverse relation with dose for less privileged workers is probably a sign that there has been selective recruitment of the most highly paid manual workers--that is, skilled craftsmen into the more dangerous occupations. Evidence of this selective recruitment was obtained by equating danger levels with levels of monitoring for internal radiation. Therefore, there should be some control for these levels in any analysis of cancer effects of the measured dose of radiation.

Female↗
PubMed1984

Job related mortality risks of Hanford workers and their relation to cancer effects of measured doses of external radiation.

This paper continues the series by Mancuso, Stewart, and Kneale (MSK) on studies of cancer risks for radiation workers at Hanford. It concentrates on the statistical problems posed by the need to estimate and control for job related mortality risks when there are several changes of occupation and no certainty about how different occupations are related to two socioeconomic factors which have strong health associations--namely, education and income. The final conclusion is that for tissues which are sensitive to cancer induced by radiation there is a risk of cancer for Hanford exposures whose dose response is curvilinear with long latency and increasing effect with increasing exposure age.

Adult↗
PubMed1983

A 12-month comparative trial of auranofin and D-penicillamine in rheumatoid arthritis.

The oral gold salt auranofin, 6 mg per day, was compared with oral d-penicillamine, 500 mg per day, in a single-blind trial in 40 patients suffering with definite or classic rheumatoid arthritis. The patients were randomly allocated into the two therapeutic regimens (19 patients auranofin; 21 patients d-penicillamine) and monitored at a minimum of four-week intervals during the first year of treatment. Significant diminution in rheumatoid disease activity, as assessed by numerous clinical and laboratory parameters, was observed in both the auranofin- and penicillamine-treated groups. No significant differences existed for these parameters between the two groups, either initially or at the end of the trial period. Ten patients were lost from the trial over the 52-week period. Three subjects were withdrawn from the auranofin-treated group (increasing severity of rheumatoid arthritis at four weeks; severe diarrhea at four weeks; probable drug-related erosive gastritis at 40 weeks). Seven subjects were permanently withdrawn from the penicillamine-treated group (four, skin rashes four to eight weeks; one, heavy proteinuria at 24 weeks; one, therapeutic failure at 32 weeks; one, compliance failure at eight weeks), and treatment was temporarily withheld in three further patients because of thrombocytopenia (two) and proteinuria (one). We conclude that both drugs are effective in rheumatoid arthritis and that the lesser toxicity with auranofin will make it a valuable addition to our therapeutic armamentarium.

Adult↗
PubMed1982

The immune system and cancers of foetal origin.

Evidence of early loss of immunological competence in cases of neoplasms occurring in juveniles was found in an analysis of OSCC data (Oxford Survey of Childhood Cancers). The effects observed included heightened sensitivity to infection from birth onwards for all types of childhood cancer, higher levels of sensitivity for leukaemia than for lymphomas, and higher levels for lymphomas than for other solid tumours. The findings as a whole are consistent with in utero loss of immunological competence, which is an essential promoter of cancers of foetal origin and thus allows the outcome of an in utero cancer induction to be influenced both by maternal levels of immunological competence and postnatal infection.

Adolescent↗
PubMed1982

Delayed effects of A-bomb radiation: a review of recent mortality rates and risk estimates for five-year survivors.

A review of published data relating to A-bomb survivors has led to the conclusion that since they were based on the mortality experiences of five year survivors estimates of radiation effects should have been controlled for two opposing forces-namely, selective survival of exceptionally fit individuals during the period of heavy acute mortality and residual disabilities. Both effects were dose-related and beyond question, and the disabilities probably included the effects of incomplete repair of bone marrow damage. Therefore, in addition to differences between high and low dose being largely obliterated, there was probably distortion of cancer effects. The two opposing forces are clearly the reason why the change from the high mortality rates of 1945-6 to the low rates of the 1950s was not accompanied by a change from a position to a negative association with dose, and imperviousness to the residual disabilities is probably the reason why sudden deaths of previously healthy individuals (exemplified by suicides) were an exception to this rule. Finally, impairment of bone marrow function probably accounts for the early epidemic of myeloid leukaemia; the apparent absence of other cancers at this time, and the relatively high dose-related death rates for blood diseases other than leukaemia.

Bone Marrow Diseases↗
PubMed1981

Hanford radiation study III: a cohort study of the cancer risks from radiation to workers at Hanford (1944-77 deaths) by the method of regression models in life-tables.

This paper reports on results from the study initiated by Mancuso into the health risks from low-level radiation in workers engaged in plutonium manufacture at Hanford Works, Washington State, USA, and attempts to answer criticisms of previous reports by an in-depth study. Previous reports have aroused much controversy because the reported risk per unit radiation dose for cancers of radiosensitive tissues was much greater than the risk generally accepted on the basis of other studies and widely used in setting safety levels for exposure to low-level radiation. The method of regression models in life-tables isolates the effect of radiation after statistically controlling for a wide range of possible interfering factors. Like the risk of lung cancer for uranium miners the dose-response relation showed a significant downward curve at about 10 rem. There may, therefore, be better agreement with other studies, conduct at higher doses, than is widely assumed. The findings on cancer latency (of about 25 years) and the effect of exposure age (increasing age increases the risk) are in general agreement with other studies. An unexplained finding is a significantly higher dose for all workers who developed cancers in tissues that are supposed to have low sensitivity to cancer induction by radiation.

Actuarial Analysis↗
PubMed1980

Pre-conception X-rays and childhood cancers.

An analysis of data collected during the course of the Oxford Survey of Childhood Cancer has shown that it is possible to recognize different facets of memory bias without systematic checking of individuals' records, and to make use of the biased data. The position of foetal irradiation in the aetiology of childhood cancers has been re-affirmed, but there is no support for the idea that exposure of parental gonads to diagnostic X-rays is conducive to cancer in the next generation.

Child↗