Biomedical subjects

C J MacLean

Publications and source records attributed to C J MacLean.

At least 91 records · Page 5Linked to original sources

PubMed1983

The effect of irradiation in the therapeutic dose range on vascular-graft material.

Samples of Dacron and Teflon tubing that were obtained from unused vascular-graft remnants were irradiated with 1000 to 8000 rad (10 to 80 Gy) and compared in tensile strength and elongation with unirradiated specimens. No significant difference in these parameters was found. These levels of single-dose irradiation may be assumed to be similar to those used in fractionated irradiation of human malignant neoplasms. Therefore, it can be concluded that irradiation at clinical dose ranges does not affect the tensile strength and elongation of vascular graft material. Polyethylene tubing, on the other hand, is strengthened to a minor degree by single dose irradiation with 1000 to 8000 rad (10 to 80 Gy).

Blood Vessel Prosthesis↗

PubMed1982

Discriminant analysis of radiation therapy procedures: the Patterns of Care Process Survey for carcinoma of the larynx.

Discriminant analysis was applied to larynx data from the Patterns of Care Study (PCS) in order to evaluate and classify radiation therapy procedures. Since PCS has recorded information on a large number of separate procedures, a method was needed to treat them coherently. Discriminant analysis provided such a method through a comprehensive score of performance. The particular discriminant score used was calculated from the contrast between facilities with and without radiation therapy resident training programs. Because residents drastically affect the practice of radiation therapy in a facility, this factor provided a foundation for analyzing the procedures themselves. Results of the discriminant analysis were used to derive a condensed list of generalized procedural criteria which contains almost all the discrimination information of the original procedures and which elucidates their relative importance and the relations among them.

Evaluation Studies as Topic↗

PubMed1981

Variation in work-up and treatment procedures among types of radiation therapy facilities: the patterns of care process survey for three head and neck sites.

The PCS Process Survey analyzed radiation therapy facilities to evaluate procedures in work-up and treatment of patients with cancer of the larynx, tongue, and nasopharynx. Types of facilities are compared to establish bench marks in performance of work-up and treatment procedures that can be used as a foundation for upgrading care and for adjusting studies to follow this paper. A statistical method is demonstrated that provides a "signature" of relative performance over a standardized set of procedural criteria. Facilities with resident training programs perform nearly all of these procedures much more consistently than do nontraining facilities. Facilities with full-time head therapists perform most procedures more consistently than do facilities with part-time heads. A third comparison of large versus small facilities shows that among training facilities size has no effect and that among full-time facilities size has a slight effect. Among part-time facilities, however, smaller ones fail to perform most procedures more often than larger facilities. The size difference is confounded with the full-time/part-time difference because part-time facilities are on the average smaller than facilities with full-time head therapists.

Follow-Up Studies↗

PubMed1977

Recurrence risks in complex inheritance with special regard to pyloric stenosis.

A large body of data on segregating families is used to generate specific recurrence risks conditional on sex and birth order for the best-fitting model of polygenes plus maternal effect. The method is general for diseases of complex inheritance, and lies within the competence of any serious genetic clinic. The question of whether consultees demand as much specificity should be subordinate to the question of whether counsellors are justified in providing less.

Birth Order↗

PubMed1977

Commingling in distributions of lipids and related variables.

In a sample of nearly 8,000 Japanese males, the distributions of casual cholesterol and triglyceride, hematocrit, glucose, uric acid, diastolic blood pressure, and weight (covariance adjusted) could not be normalized by a power transform and were significantly better fitted by a mixture of distributions. The evidence for admixture was nonsignificant for systolic blood pressure, significant but unimpressive for height and weight, and strong for the remaining variables. The minor component corresponded to high values, in low frequency except for triglyceride and glucose. These results favor an interpretation of elevated levels in terms of distinct entities, genetic or environmental or both, rather than cumulative small effects only. These entities appear to be megaphenic (i.e., with effects exceeding one phenotypic standard deviation). Consequences of this hypothesis are discussed.

Aged↗

PubMed1975

Analysis of family resemblance. V. Height and weight in northeastern Brazil.

Sib correlations for height and weight decrease with absolute age difference. Parent-child correlations increase with age of child, with greater resemblance to the mother than the father. Estimates of the relative variance due to common environment are greater, and heritability estimates less, than for earlier studies. Heritability is less for adults than children. There is no significant major locus for height or weight.

Adult↗

PubMed1975

Analysis of family resemblance. IV. Operational characteristics of segregation analysis.

In simulated data, segregation analysis of quantitative traits was found to be powerful for resolving a major locus from polygenic and cultural inheritance. It is reasonably robust against a variety of deviations from the model if and only if a major locus, polygenic heritability, and environment common to sibs are simultaneously included in the model, and heterogeneity tests among mating types are performed. Most of the information in quantitative data about a major locus is lost when reduced to affection status.

Environment↗

PubMed1974