Biomedical subjects
Publications and source records attributed to P D Jarvis.
A model is presented for the structure and evolution of the eukaryotic and vertebrate mitochondrial genetic codes, based on the representation theory of the Lie superalgebra A(5,0) approximately sl(6/1). A key role is played by pyrimidine and purine exchange symmetries in codon quartets.
A 2-year retrospective review of 238 cases of acute scrotal pain encountered in a children's hospital emergency department is presented. The incidences of testicular torsion, torsion of a testicular appendage, and epididymitis were 16%, 46%, and 35%, respectively. Testicular salvage was critically dependent on the interval between onset of pain and surgical intervention. No testis likely to have been viable at the time of presentation was "lost." The diagnostic error rate on first encounter was 7%, resulting in 10 negative scrotal explorations. With the exception of cases of far-advanced necrotic testes, both color Doppler ultrasound and radioisotope imaging were highly specific diagnostic modalities. Thirty-nine percent of the children with epididymitis who underwent investigation were found to have either structural or functional urinary tract abnormalities. Noninvasive urodynamic studies appear to be useful screening modalities in older children with epididymitis.
PURPOSE: Bladder resistance to bacterial infection after gastrocystoplasty, ileocystoplasty and cecocystoplasty was investigated in the rat. MATERIALS AND METHODS: Bladders were infected with Escherichia coli 6 to 13 months after augmentation and urine culture was obtained weekly for 3 months. RESULTS: No differences were observed in the number of infected animals within each group or electrolyte data among groups. The number of animals infected after surgery but before E. coli challenge was lowest in the gastrocystoplasty group. Bladder stones formed only in ileocystoplasty and cecocystoplasty groups. No group had a change in urinary pH. CONCLUSIONS: Gastrocystoplasty may be associated with a lower incidence of spontaneous infection and stone formation. An aggressive infection protocol may have masked differences in susceptibility to infection. Since urinary pH was unchanged after gastrocystoplasty, use of the rat may not be appropriate for augmentation studies.
The systematics of indices of physico-chemical properties of codons and amino acids across the genetic code are examined. Using a simple numerical labelling scheme for nucleic acid bases, A=(-1,0), C=(0,-1), G=(0,1), U=(1,0), data can be fitted as low order polynomials of the six coordinates in the 64-dimensional codon weight space. The work confirms and extends the recent studies by Siemion et al. (1995. BioSystems 36, 231-238) of the conformational parameters. Fundamental patterns in the data such as codon periodicities, and related harmonics and reflection symmetries, are here associated with the structure of the set of basis monomials chosen for fitting. Results are plotted using the Siemion one-step mutation ring scheme, and variants thereof. The connections between the present work, and recent studies of the genetic code structure using dynamical symmetry algebras, are pointed out.