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Biomedical subjects

M Phipps

Publications and source records attributed to M Phipps.

3 recordsLinked to original sources

Plasmid incidence rate and conjugative chloramphenicol and tetracycline resistance plasmids in Malaysian isolates of Salmonella typhi.

Seven (6.1%) of 115 strains of Salmonella typhi isolated from Malaysian patients harbored a single large plasmid of 71 to 166 mD. Two of the seven plasmid-bearing strains were resistant to chloramphenicol (Cm) and tetracycline (Tc) and they transferred Cm and Tc resistance traits to Escherichia coli K12 at frequencies from 1.6 x 10(-7) to 1.9 x 10(-6). Agarose gel electrophoresis provided evidence that the resistance traits were cotransferred on a conjugative plasmid. The significance and importance of these results are discussed.

Chloramphenicol Resistance

Carcinogenic implications of the neighborhood coherence principle (NCP).

A new hypothesis on carcinogenesis is set forth on the basis of the neighborhood coherence principle (NCP). NCP constitutes a general rule of pattern formation and maintenance. According to this principle, a system of interacting cells can produce and maintain a spatial organization by virtue of cell-cell communication. This hypothesis suggests that this homeostasis primarily results from a NCP-like process implying cell-cell communication. Each cell is constrained by its neighbors to maintain the mature phenotype despite its inherent individual variability. If the cell-cell mature communication happens to be impaired, tissue homeostasis is disrupted and a proliferative state can be initiated. A further potential effect may result from the establishment of NCP-like communication specific for proliferative cells allied to paracrine and outocrine factors which can lock the cells into the proliferative mode. Most mechanisms implied in this hypothesis have already been investigated. There is a large body of experimental results supporting the role of junctional communication in cooperative metabolism, growth, differentiation and tumour-related events. This new hypothesis provides a framework within which these known facts may be put in a theoretical perspective; it might well constitute the unifying theory--as yet missing--in carcinogenesis.

Animals