PubMed Health⌕ Search

Biomedical subjects

E C Knoblock

Publications and source records attributed to E C Knoblock.

10 recordsLinked to original sources
PubMed1990

Accuracy and precision of methods for theophylline measurement in physicians' offices.

We tested the accuracy and precision of five theophylline methods intended for use in physicians' offices. The Syntex AccuLevel, Ames Seralyzer, and 3M Diagnostics TheoFAST methods were less reproducible (CVs 6.3% to 9.2%) than the Abbott Vision and Kodak DT-60 (CVs 2.2% to 3.3%). Caffeine interfered with the Vision, Seralyzer, and AccuLevel methods, and theobromine interfered with the Vision, Seralyzer, and TheoFAST methods. Only the DT-60 method was free from interference from any of the 24 compounds tested. Results by all methods correlated well with those by the HPLC comparison method (Clin Chem 1981;27:1931-3) and by the Abbott TDx method for assay of 100 serum (or, when appropriate, paired whole-blood) samples. The frequency of sample results differing from the comparison method by greater than 2.0 mg/L was as follows: TDx, 11%; Vision (serum), 12%; Vision (whole blood), 18%; DT-60, 14%; AccuLevel, 18%; Seralyzer, 25%; and TheoFAST, 31%. The Kodak DT-60 method was the most nearly accurate and precise among these physician's office methods. Some physician's office methods for theophylline analysis are not adequate to guide dosage adjustments.

Humans↗
PubMed1988

Inaccuracies in digoxin measurement.

Six commercial digoxin immunoassay kits were evaluated for their accuracy of calibration and their extent of interference by digoxin-like immunoreactive substance (DLIS). Calibration accuracy was investigated with digoxin reference standards in pooled human serum. The Abbott and Becton Dickinson kits underestimate while the other kits overestimate digoxin concentration. The magnitude of this bias generally increases with increasing concentration of digoxin. Sera from digoxin-free patient populations with potential DLIS interference--pregnant women, newborns, hypertensives, and uremics--were analyzed with each kit. Healthy subjects not on digoxin therapy served as controls. Groups with DLIS interference, as exemplified by a significant difference of p less than 0.05 from controls, are: Abbott--newborns and pregnant women; Becton Dickinson--newborns and pregnant women; Dade--no difference; Dupont--newborns, uremics, pregnant women, and hypertensives; Kallestad--newborns; and Syva--newborns. The limitations of each individual digoxin method should be realized for DLIS interference and bias, and patient results from that method should be interpreted accordingly.

Adult↗
PubMed1982

Rapid quantitation of serum immunoglobulins with a miniature centrifugal analyzer.

For these quantitative turbidimetric assays for immunoglobulins IgG, IgA, and IgM in serum, the reagents used are commercially available in kit form. The two-point assays are performed with a miniature centrifugal analyzer (GEMENI, Electro-Nucleonics, Inc.). The reading taken 5 s after mixing is used to correct for specimen turbidity. Run-to-run precision (CV) was typically 5% (range: 3.0-8.7%). Excellent correlation with radial immunodiffusion was observed for each test (r greater than 0.98 for each test). The dynamic range of each test extends above and below the reference-interval ranges.

Centrifugation↗
PubMed1981

Measurement of serum lipase activity with the oxygen electrode.

We describe the measurement of lipase (triacylglycerol lipase; EC 3.1.1.3) in serum by continuous monitoring of relative rates of oxygen consumption with a polarographic oxygen electrode. The reactions described by Proelss and Wright (Clin. Chem. 23: 522-531, 1977) are used: trilinolein, with lipase catalysis, yields linoleic acid, which reacts with oxygen in the presence of lipoxygenase. Lipase activity is measured by comparing the zero order reaction rate of the specimen with that obtained with linoleic acid standards. Results for lipase (y) correlated well with those by the copper-soap method of Myrtle and Zell (x) (Clin. Chem. 21: 1469-1473, 1975); y = 0.33x - 11; r = 0.98; n = 34. Results are unaffected by specimen dilution, and the standard curve is linear to 520 U/L. Day-to-day precision (CV) is 10.4% for normal activities, 6.1% for above-normal activities. We believe the method offers a precise, practical approach to lipase analysis.

Blood Chemical Analysis↗