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Biomedical subjects

A M Stewart

Publications and source records attributed to A M Stewart.

At least 73 records · Page 4Linked to original sources
PubMed1978

Pre-cancers and liability to other diseases.

Data of 10,556 case-control pairs from the Oxford Survey of Childhood Cancers and related sources have shown that when cancers originate in the reticuloendothelial system (RES neoplasms) they are liable to cause loss of immunological competence before they are clinically recognizable. Since these early effects may have lethal consequences, the true prevalence of RES neoplasms is difficult to identify, especially in infection-sensitive age groups and populations with high death rates from infection. An inevitable consequence of a nuclear holocaust is a high infection death rate. Therefore, a population of A-bomb survivors is a totally unsuitable one for studying the precise nature of the association between ionizing radiation and human cancers.

Adolescent↗
PubMed1977

Diffuse xanthogranulomatous pyelonephritis in children: an unrecognized variant.

Xanthogranulomatous pyelonephritis in childhood has been thought to exist only in focal form. We encountered 2 cases of diffuse xanthogranulomatous pyelonephritis in children and have found 3 others reported in the literature, making it necessary to change this concept. The essential radiologic and pathologic differences between focal and diffuse xanthogranulomatous pyelonephritis are reviewed.

Child, Preschool↗
PubMed1977

Age variation in the cancer risks from foetal irradiation.

A modified Mantel-Haenszel analysis of data from the Oxford Survey of Childhood Cancers has shown that cases associated with foetal irradiation (X-rayed cases) accounted for a higher proportion of deaths between 5 and 10 years than of earlier or later deaths. This finding is compatible with somewhat later origins for the cancers actually caused by the radiation exposures (radiogenic cases) than for other (idiopathic) cases which proved fatal before 10 years of age. Therefore the usual time for incurring congenital anomalies (or the first trimester of foetal life) could be the commonest time for initiating childhood cancers. The theoretical implications of this and other findings of the Oxford Survey are discussed within the framework of a theory which assumes that all mutant cells have cancer potentialities and that defects in the immune surveillance mechanism favour multiplication of these cells (or endogenous sources of self-replicating foreign proteins) as well as live pathogens (or exogenous sources of self-replicating foreign proteins).

Age Factors↗
PubMed1977

Congenital oesophageal stenosis.

A case of congenital oesophageal stenosis presenting shortly after birth is reported. Treatment by daily dilatation with a bead on a continuous thread loop was carried on at home over several months. This proved to be a simple, safe, and effective treatment.

Dilatation↗
PubMed1976

Mantel-Haenszel analysis of Oxford data. I. Independent effects of several birth factors including fetal irradiation.

Data from the Oxford Survey of Childhood Cancers were subjected to the Mantel-Haenszel procedures to recognize independent effects of associated factors in retrospective data. Our results showed that several birth factors, including fetal irradiation, social class, maternal age, and sibship position, exerted separate effects on childhood cancers in general, and reticuloendothelial system neoplasms in particular.

Adolescent↗
PubMed1976

Mantel-Haenszel analysis of Oxford data. II. Independent effects of fetal irradiation subfactors.

A Mantel-Haenszel analysis of fetal irradiation subfactors indicated that most of the "extra" X-rayed cases in the Oxford Survey of Childhood Cancers were radiation induced. First trimester exposures were rare but probably ten times more dangerous than later exposures. Ratios of observed: expected numbers of cancer deaths were lower for children with abnormal X-rays than for other X-rayed children, and lower for recent than remote exposures. The first of these differences was probably due to several antenatal conditions having positive associations with obstetric radiography and several causes of early (noncancer) deaths; the second one was probably due to a progressive lowering of film doses between 1940 and the present time. A rare cause of fetal irradiation (hydramnios), whose associations with congenital defects are well documented, led to the discovery that two faults in the International Classification of Diseases and Causes of Death have contributed to mistaken ideas about the etiology of childhood cancers: Neoplasms were not listed among the official causes of stillbirths, and cystic tumors of the kidneys and lungs of infants were not listed as neoplasms.

Female↗
PubMed1975

Cot deaths.

Explore the source record for details and available documents.

Female↗
PubMed1975

Pre-natal irradiation and childhood malignancy: a review of British data from the Oxford Survey.

This paper reviews data relating to obstetric radiography from the Oxford Survey of Childhood Cancers, i.e. for deaths in Britain from 1953 to 1967. Some 8513 cases were traced and used in the analyses, together with an equal number of matched controls. The relative risk estimate (1-47 overall) does not vary significantly between different tumour groups, for different ages at death, nor between sexes. Other epidemiological factors-sibship position, maternal age, social class, region of residence and maternal morbidity-are analysed and show varying degrees of association, but not sufficient to "explain" the observed risk in terms of a selection effect. The dependence of the risk on the number of films exposed is highly significant and adequately described by a linear relationship. The timing of and reason for the exposure are also examined. Analysis of the risk by year of birth shows a pattern of steadily declining risk for both solid and haematopoietic tumours; this may be partly attributable to lower radiation doses per film exposed but is also due to the smaller numbers of films used. A consequence may well be that the risk-always of small clinical significance-would become virtually undetectable in future investigations.

Adolescent↗