Biomedical subjects
Publications and source records attributed to C O'Donovan.
Most atypical Mycobacterium infections of the hand are caused by Mycobacterium marinum. We are presenting a rare case of a Mycobacterium chelonei tenosynovitis. The correct diagnosis is important because the chelonei species is resistant to most antituberculosis drugs. Treatment should include surgical debridement and long-term chemotherapy after sensitivities have been determined.
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Five mutant versions of aspartate transcarbamylase have been isolated, all with single amino acid substitutions in the catalytic chain of the enzyme. A previously isolated pyrB nonsense mutant was suppressed with supB, supC, supD and supG to create enzymes with glutamine, tyrosine, serine or lysine, respectively, inserted at the position of the nonsense codon. Each of these enzymes was purified to homogeneity and kinetically characterized. The approximate location of the substitution was determined by using tryptic fingerprints of the wild-type enzyme and the enzyme obtained with a tyrosine residue inserted at the position of the nonsense codon. By first cloning the pyrBI operon, from the original pyrB nonsense strain, followed by sequencing of the appropriate portion of the gene, the exact location of the mutation was determined to be at position 209 of the catalytic chain. Site-directed mutagenesis was used to generate versions of aspartate transcarbamylase with tyrosine and glutamic acid at this position. The Tyr209 enzyme is identical with that obtained by suppression of the original nonsense mutation with supC. The two enzymes produced by site-directed mutagenesis were purified using a newly created overproducing strain. Kinetic analysis revealed that each mutant has an altered affinity for aspartate, as judged by variations in the substrate concentration at one-half maximal activity. In addition, the mutants exhibit altered Hill coefficients and maximal activities. In the wild-type enzyme, position 209 is a tryptophan residue that is involved in the stabilization of a bend in the molecule near the subunit interface region. The alteration in homotropic cooperativity seems to be due to changes induced in this bend in the molecule, which stabilizes alternate conformational states of the enzyme.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Bone Anchored Hearing Aids have both cosmetic and acoustic advantages over most conventional hearing aids and hence is a popular choice today. We report the first Irish group of patients who received a BAHA over a six year period of time and evaluated outcomes of these subjects using subjective assessment. The medical records of all patients who received a BAHA at the Mater and Children's University Hospital, Dublin, were reviewed. A questionnaire had been sent to the patients to obtain long-term subjective information. Twenty three patients were identified. The commonest indication for surgery was found to be the presence of a discharging mastoid cavity, followed by congenital ear malformations. Surgical procedures were carried out as a single stage in 16 patients. Questionnaires were sent to 19 patients; sixteen patients responded in total. BAHA has a beneficial outcome to the quality of life and has significantly reduced ear discharge. The one stage technique was found to have a lower complication rate.