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P R Burch

Publications and source records attributed to P R Burch.

At least 73 records · Page 4Linked to original sources
PubMed1979

Perthes' disease: a new genetic hypothesis.

We describe the sex and age distributions of the onset of Perthes' disease in our own and six other large published series. The mathematical features of these distributions, together with the evidence for familial aggregations, agree with the theory that the disease is autoaggressive in aetiology and that two genetically-distinctive groups are at risk. We consider the frequency of affected sides - left, right, bilateral - in our own and other series: concordance for affected side(s) within sibships suggests that laterality might be genetically determined. Following Gray et al. we believe that predisposition to the disease is polygenic and we propose a simple scheme - involving an X-linked "recessive" factor and an autosomal homozygous allele in each genotype - that is reasonably consistent with the slender evidence.

Age Factors↗
PubMed1979

A critique of Katz's 'high LET constraint on low LET survival'.

Katz's interpretation of the connexion between RBE and LET is contrasted with a version published previously by Burch. The implications of Katz's model for dose-response relations apply only at ultra-high absorbed doses in Burch's model. In the latter, the shoulder on type-C survival curves for mammalian cells is explained in terms of Haynes' repair model. Under certain conditions the repair model becomes mathematically equivalent to the 'alpha--beta' model; under some other conditions it becomes equivalent to the 'two-component' model. The formulation of a new repair hypothesis, based on the idea of an inducible repair mechanism, is also set out. It is argued that Katz's 'supralinearity index' is appropriate to the induction of (rare) mutations but inappropriate to cell survival, for which an alternative index is proposed. Certain plausible hypotheses of radiobiological action conflict with Katz's 'logical constraint' which, it is contended, is neither logical nor valid. In conclusion, although experimental findings for some radiobiological systems conform to Katz's 'constraint', the frequently observed violations should not necessarily be regarded as artefacts.

Cell Survival↗
PubMed1979

Hip dysplasia without dislocation in one-year-old boys.

Six boys were examined during the second year of life, each with symptoms in one hip. The affected femoral capital epiphysis was smaller or more irregular (or both) than that of the unaffected hip but was neither subluxed nor dislocated. The subsequent radiographs revealed changes similar to those in severe Perthes' disease. Nevertheless, we give reasons for believing that this disorder in boys under two years of age should be distinguished from Perthes' disease.

Bone Diseases, Developmental↗
PubMed1977

Perthes' disease. A study of radiological features.

A study is presented of the radiographs of 68 patients with unilateral Perthe's diseasemtwo types of Perthe's disease are identified: 'fragmenting' and 'non-fragmenting'. The two radiological types of the disease showed no significant differences in the age at diagnosis, the duration of symptoms before diagnosis and the duration of the disease. However, the radiologically-measureable results at healing, in terms of the epiphyseal, acetabular, acetabulum-head and comprehensive quotients were all very significantly worse when fragmentation had developed.

Age Factors↗