Guidelines causing iatrogenic disease?
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Biomedical subjects
Publications and source records attributed to E M Wise.
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Several natural isolate E. coli strains highly resistant to sulfonamides and antibiotics are shown to contain a sulfonamide-resistant dihydropteroate synthase (2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine-diphosphate:4-aminobenzoate 2-amino-4-hydroxydihydropteridine-6-methenyltransferase, EC 2.5.1.15) in addition to the normal sensitive enzyme. The resistant dihydropteroate synthases examined are determined by an R plasmid and are smaller and less heat stable than the normal sulfonamide-sensitive enzyme. One synthase resistant to any sulfonamide tested, and to sulfanilic and arsanilic acids, was still inhibited by several non-sulfonamide analogs of p-aminobenzoate. Citrobacter and Klebsiella pneumoniae strains also show similar mechanisms of sulfonamide resistance.
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Adenosine 3':5'-cyclic monophosphate added to exponentially growing cells of Hemophilus influenzae strain Rd increases competence for transformation 100- to 10,000-fold. Cyclic AMP added to near-stationary or stationary cells does not increase competence over the high level normally found in the early stationary phase.
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Bacterial phosphodiesterases have been found that are capable of cleaving the backbone of teichoic acid. Such enzymes have not been reported previously. An aerobic, gram-negative, rod-shaped bacterium producing this activity was detected and isolated by autoradiography of soil suspensions growing on minimal medium containing (32)P-labeled Bacillus subtilis ATCC 6051 cell walls as the sole phosphorus source. Broken-cell preparations are capable of depolymerizing teichoic acids in media of low ionic strength at near-neutral pH values. An active teichoicase is also present in B. subtilis, ATCC 6051 (the Marburg strain), especially in sporulating cultures.
The principal autolytic enzyme activity of the cell sap of Staphylococcus aureus H has been purified 400-fold. It is an N-acetylmuramyl-l-alanine amidase. This enzyme has a molecular weight of 8 to 10 x 10(5), a pH optimum of 7.3, an ionic strength optimum of 0.16 m and a K(m) of 10(-3)m murein repeating units.
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Staphylococcus aureus strain H has an autolytic activity which can be found in the cell wall but is most easily obtained from high-speed supernatant fractions of broken-cell preparations. As measured either turbidimetrically or radioactively, this activity is much greater on murein extracted from penicillin-treated cells than on murein extracted from normal cells.
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