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Biomedical subjects

D R Marshall

Publications and source records attributed to D R Marshall.

52 records · Page 3Linked to original sources
PubMed1977

Reconstruction of the breast following radical mastectomy.

A method of reconstruction of the breast following radical mastectomy is presented. The technique involves the use of an individually made Silastic prosthesis inserted three to six months after the mastectomy. A new simple method of nipple reconstruction is described, and the total restoration can be achieved in one operation. It is suggested that reconstruction of the breast be considered more frequently in patients subjected to mastectomy.

Breast↗
PubMed1975

The charge-state model of protein polymorphism in natural populations.

Routine electrophoretic surveys for genetic variation in natural populations depend primarily upon detecting differences in the net charge carried by a protein. We have calculated the proportion of base substitutions which would yield an electrophoretically detectable mutant protein, and the relative mutation rates among different chare classes, under a variety of simplifying assumptions. These calculations indicate that: (i) only 25 per cent of all single base mutations would lead to a charge change on a protein molecule. (ii) five distinct classes of electrophoretic variants can be generated from a specified protein by single base substitutions. (iii) the relative mutation rates differ markedly among the different charge classes which can be generated by single base substitutions. The estimates of the proportion of electrophoretically detectable mutant proteins and relative mutation rates among charge classes were relatively robust to changes in assumptions concerned with the kind and site of base substitutions and the amino acid composition of the protein.

Alleles↗
PubMed1975

Population differentiation under the charge state model.

The extent of divergence between partially isolated sub-populations for electrophoretically detectable alleles was formulated assuming the island model of migration and the charge state model of mutation. At equilibrium the ratio of the variance of charge between the means of k different islands to the average within-island variance of charge was shown to be approximately 4Nemk2/(k-1)2 where Ne is the effective size of each island population and m is the migration rate. This ratio was calculated from published data for eight polymorphic loci in six island populations of Drosophila willistoni. Under the assumption that all variants are selectively neutral, migration rates of greater than 10 adults per generation per island are required to explain the observed similarity of the allelic profiles in D. willistoni. Since the islands studied appear to be virtually completely isolated it was concluded either that the observed protein variants are adaptive and maintained in populations by some form of balancing selection or that the observed variants themselves are neutral but natural selection acts to restrict the appearance of more extreme variants in the charge carried.

Drosophila↗
PubMedDate not supplied

Evidence for adherence-dependent cytotoxicity of Alcaligenes faecalis in turkey tracheal organ cultures.

A virulent isolate of Alcaligenes faecalis was examined in turkey tracheal organ cultures (TTOC) for adherence using immunofluorescent staining and for cytotoxicity using light microscopic observation. Treatment of the bacterial culture with trypsin, antiserum specific for A. faecalis, and N-acetylneuraminic acid inhibited the ability of the organism to adhere to TTOC. Treatment of the bacterium with D-galactose partly decreased adherence of the bacterium. Those treatments that inhibited the adherence of A. faecalis also inhibited the cytolytic activity in TTOC. Treatment of the bacterial culture with D-galactose only partly decreased the cytolytic activity. These data indicate that adherence of the organism to TTOC is necessary for the cytolytic activity characteristic of A. faecalis isolates capable of causing alcaligenes rhinotracheitis in turkeys.

Adhesiveness↗