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Biomedical subjects

W L Baker

Publications and source records attributed to W L Baker.

32 records · Page 2Linked to original sources
PubMed1985

A sensitive enzymic assay for benzylpenicillin.

A method has been developed for the determination of sodium benzylpenicillin concentrations in the range 3.3-33 micrograms/ml. 6-Aminopenicillanic acid is released from the benzylpenicillin by the action of the enzyme penicillin acylase and is estimated from its reaction with fluorescamine at pH 4. 7-Aminocephalosporanic acid shows a similar trend to 6-aminopenicillanic acid in its reaction at pH 4. The open beta-lactam ring form of each compound shows little fluorescence with fluorescamine at pH 4 but shows strong fluorescence in the pH range 7-9. 6-Aminopenicillanic acid and its open beta-lactam ring form give different fluorescent responses to increasing volumes of a solution of the fluorigenic agent at pH 7.8. This effect can be used to estimate concentrations in a mixture of the two components providing other amino material is absent.

Hydrogen-Ion Concentration↗
PubMed1985

Hypophosphatemia.

Explore the source record for details and available documents.

Alcoholism↗
PubMed1984

A sensitive procedure for screening microorganisms for the presence of penicillin amidase.

A procedure is described for screening bacteria for the presence of penicillin amidase. Cells, grown in the presence of phenylacetic acid, are incubated with phenoxymethylpenicillin (type I), benzylpenicillin (type II) or ampicillin and the 6-aminopenicillanic acid formed is detected and quantitatively estimated by its strong reaction with fluorescamine at pH 4. There is no requirement for separation of the penicillin substrate from the product but when alpha-aminobenzylpenicillin derivatives are used as enzyme substrates the amount of 6-aminopenicillanic acid formed must be determined by calculation. The procedure allowed positive and reliable identification of penicillin amidases in six organisms known to produce the enzyme and indicated that some of these enzymes had different properties in reactivity towards alpha-aminobenzylpenicillin derivatives.

Amidohydrolases↗
PubMed1983

Activity of penicillin-acylase-producing bacteria against alpha-aminobenzylpenicillins.

A method has been developed for the chemical analysis of individual alpha-aminobenzylpenicillin derivatives. This analytical procedure may conveniently be used to determine whether microorganisms possess penicillin acylases which show considerable activity against alpha-aminobenzylpenicillin derivatives. The method is not sufficiently sensitive to determine low levels of enzyme activity. Organisms known to produce penicillin acylases which are active against benzyl- or phenoxymethylpenicillin showed variable responses to alpha-aminobenzylpenicillin substrates. A significant difference in activity profile was noted between the intracellular enzyme of Escherichia coli and the extracellular enzyme of Bacillus megaterium.

Amidohydrolases↗
PubMed1983

Application of the fluorescamine reaction with 6-aminopenicillanic acid to estimation and detection of penicillin acylase activity.

6-Aminopenicillanic acid may be quantitatively estimated by its reaction with fluorescamine in the concentration range of 1 to 10 micrograms/ml. The difference in reactivity between 6-aminopenicillanic acid and benzylpenicillin, which does not react with fluorescamine, can be used to determine penicillin acylase activity and obtain data on enzyme parameters and inhibitors. Unlike amino acids and peptides, 6-aminopenicillanic acid reacts strongly with fluorescamine at pH 4, an observation which can be used to determine the presence of penicillin acylase in whole bacterial cell preparations.

Amidohydrolases↗
PubMedDate not supplied

Sustaining work redesign innovations through shared governance.

Organizational change, in the form of work redesign, is widespread in hospitals across the country. How can the resulting patient-focused care models be sustained when "sustaining" means continuously changing and improving? The authors describe one hospital's use of a multidisciplinary shared governance system to provide the structure and process support for the innovative changes initiated by work redesign.

Costs and Cost Analysis↗
PubMedDate not supplied

Biotin deficiency in a patient with short bowel syndrome during home parenteral nutrition.

A 54-year-old woman with short bowel syndrome was supported with home parenteral nutrition. Six months after receiving 2200 kcal/day of balanced home parenteral nutrition without biotin, she developed biotin deficiency with complete hair loss, eczematous dermatitis, waxy pallor, lethargy, and hypersthesias . Blood and urine samples were collected prior to treatment. Serum zinc was 64 micrograms/dl (nl 50-150 micrograms/dl), and the triene/tetraene ratio was 0.068 (nl 0.4), thereby ruling out zinc and essential fatty acid deficiencies. Serum biotin was 332 pg/ml (nl 520 +/- 220 pg/ml), and urine biotin was 5.22 ng/mg of creatinine (nl 4.3-95 with a mean of 30.2 ng/mg creatinine). The same parenteral nutrition regimen was contained and oral biotin was administered (10 mg/day). After 3 wk, serum and urine biotin levels were 650 pg/ml and 35.6 ng/mg creatinine, respectively. New hair growth was evident and all of her other symptoms resolved. Intravenous biotin was then provided (5 mg/day) for a month after which serum and urine biotin levels were 1316 pg/ml and 178 ng/mg creatine, respectively. The patient has been subsequently maintained on an intravenous multivitamin product containing 60 micrograms biotin per daily dose and remains free of signs and symptoms of biotin deficiency.

Biotin↗