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Biomedical subjects

P R Bach

Publications and source records attributed to P R Bach.

8 recordsLinked to original sources
PubMed1984

Quantitative extraction of amphotericin B from serum and its determination by high-pressure liquid chromatography.

Therapeutic concentrations of amphotericin B in serum were measured by reversed-phase liquid chromatography with detection at 386 nm. Complete recovery of the drug and the internal standard from a 1-ml serum sample was achieved by pretreating the sample with guanidine hydrochloride and extracting it with a disposable reversed-phase phenyl extraction column. The method was sensitive to 0.005 micrograms of amphotericin B per ml and linear to at least 5 micrograms/ml. Coefficients of variation were 4.8% within-run and 6.3% between-run.

Amphotericin B↗
PubMed1983

Determination of nifedipine in serum or plasma by reversed-phase liquid chromatography.

Therapeutic concentrations of nifedipine in serum or plasma were measured by reversed-phase liquid chromatography, with detection by ultraviolet absorbance at 235 nm. In the procedure a disposable reversed-phase extraction column is used. A 1-mL sample is required. The method is sensitive to 3 micrograms of nifedipine per liter and the standard curve is linear to at least 400 micrograms/L. Coefficients of variation at 100 micrograms/L were 2.2% within-run, 2.8% between-run. The method has been used to determine nifedipine in patients involved in a test of its efficacy in treating muscular dystrophy.

Chromatography, High Pressure Liquid↗
PubMed1980

Structural glycoprotein, fact or artefact.

It has been repeatedly claimed that structural glycoprotein or SGP is a major component of many connective tissues, particularly aorta. SGP is usually defined as material extractable from tissue with chaotropic agents such as urea and having an amino acid composition matching that of other, similar extracts. It has been claimed that SGP comprises 10-60% of the dry weight of aortic tissue. This paper describes a study in which aorta was exhaustively extracted with agents previously claimed to extract SGP. All the extracts yielded mixtures of proteins which, upon separation by polyacrylamide gel electrophoresis, were found to consist largely of actin, collagen, myosin and other known proteins. No significant quantity of any one unidentified protein was found which could have been SGP. This study casts grave doubt upon the existence of SGP as a major component of aorta.

Adenosine Triphosphate↗
PubMed1980

Stability of standard curves prepared for EMIT homogeneous enzyme immunoassay kits stored at room temperature after reconstitution.

We examined the stability of standard curves obtained with use of homogeneous enzyme immunoassay reagents (EMIT; Syva Corp., Palo Alto, CA) for assay of lidocaine, procainamide, N-acetylprocainamide, gentamicin, and theophylline, when stored at room temperature (23-24 degrees C) after reconstitution of the lyophilized materials. Standards were run and curves obtained for as long as 16 days after reconstitution. All standard curves were acceptable, according to the criteria specified in Syva product literature. Absorbance changes for all calibrators, including the zero calibrator, increased gradually with time. Increases of non-zero calibrators were largely offset by a parallel increase in the zero calibrator, such that the quantity delta A--delta A0 was very nearly constant with time. Standard curves based on the quantity delta A--delta A0 can be used for longer than curves based only on delta A.

Acecainide↗
PubMedDate not supplied

Chemistry test ordering patterns after elimination of predefined multitest chemistry panels in a children's hospital.

Predefined multitest chemistry panels (PMCPs) have constituted a large proportion of laboratory tests and patient charges, even in pediatric settings, despite the absence of documented clinical utility for PMCPs and the general availability of random access analyzers that do not require predefined test combinations. We eliminated PMCPs in our tertiary children's hospital but placed no other restrictions on ordering, and observed a 32.7% reduction in the number of automated chemistry tests ordered. All 23 tests in the previous PMCPs showed a decline in utilization, >50% for 8 of the tests and 20-50% for 13 others, and this change was sustained throughout an 8-month follow-up period. The total number of orders for one or more tests increased by 8.2%, but the variety of combinations that were ordered increased by 280%. The most substantial changes included a decrease in the number of orders for combinations of >15 tests, and increases in the number of orders for single tests and combinations of 2 to 5 tests. Orders for combinations identical to all of the former PMCPs declined, with the exception of the 4-test electrolyte panel. There was a marked decline in orders for a 7-test panel identical to the recently defined HCFA-AMA Basic Metabolic Panel, and orders for combinations identical to the HCFA-AMA Liver Function and Extended Metabolic panels were vanishingly rare and nonexistent, respectively. The calculated reduction in patient charges was much greater than actual cost savings, but the reduction in total tests and increase in the variety of test combinations suggest that significant savings can be realized if clinicians are encouraged to order only the tests or combinations they need without imposing procedural, financial, and regulatory burdens.

Clinical Chemistry Tests↗