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Biomedical subjects

E C Toren

Publications and source records attributed to E C Toren.

13 recordsLinked to original sources
PubMed1979

Dual-detector-post-column reactor system for the detection of isoenzymes separated by high-performance liquid chromatography. I. Description and theory.

We describe a dual-detector-post-column chromatographic reaction detector system that corrects for substances present in biological samples that interfere with the measurement of isoenzymes separated on a chromatographic column. The response observed at the detector in front of the reaction coil is mathematically dispersed, time transformed and subtracted from the detector behind the coil to produce a blank corrected chromatogram. The same computer program calculates peak areas and other chromatographic parameters such as height equivalent to a theoretical plate and retention time. In addition, we have evaluated the dispersion effects caused by various changes in our experimental system.

Chromatography, High Pressure Liquid↗
PubMed1979

Dual-detector-post-column reactor system for the detection of isoenzymes separated by high-performance liquid chromatography. II. Evaluation and application to lactate dehydrogenase isoenzymes.

We describe the separation of lactate dehydrogenase isoenzymes by high-performance liquid chromatography-anion-exchange columns and their quantitation by a computer-controlled, dual-detector post-column reaction system. The recoveries from the separation column were ca. 90%. The dynamic range of the system was linear over about three orders of magnitude from 3 to 1500 U/l. The coefficient of variation for isoenzyme peak areas was ca. 2%. The method is compared to the classical electrophoresis measurement and shows increased speed, resolution, precision and accuracy.

Chromatography, High Pressure Liquid↗
PubMed1979

Statistical analysis of method comparison data. Testing normality.

A Lilliefors test of normality has been applied to data from precision and accuracy studies. Most data sets tested as non-normal. Simulation studies showed that the test is extremely sensitive to the rounded, narrowly distributed data that are typical of method performance studies in clinical chemistry. The Lilliefors test can be modified to be applicable to rounded data so that it gives fewer indications of non-normality. The authors conclude that the selection of a test of normality requires careful study of the properties of the test. Otherwise, the subsequent choice between parametric and nonparametric statistics may not be meaningful.

Chemistry, Clinical↗
PubMed1979

New developments in analysis of isoenzymes separated by "high-performance" liquid chromatography.

We have developed two enzyme analyzers for use in "high-performance" liquid chromatography. In both systems two detectors are used, placed after the column effluent has been combined with assay reagent. In one system, an absorbance detector is placed before and after a post-column reaction coil. Peaks observed at one detector are subtracted from those at the other, to produce a two-point measurement of enzyme activity. The linear dynamic range was 17--1700 U/L for lactate dehydrogenase (EC 1.1.1.27). In the other system, two reaction coils were used and a single fluorescence detector was placed at the end of each coil. These coils were kept at different temperatures, and an automated switching valve diverted equal amounts of column effluent and reagent into both coils. The fluorescence readings were then subtracted to produce a differential measurement of enzyme activity. The linear dynamic range was 20--1000 U/L. We used both systems to chromatographically analyze lactate dehydrogenase isoenzymes, and could separately determine both the distribution and activity of sample isoenzymes.

Autoanalysis↗
PubMed1978

Computer-controlled instrument system for sequential chemical testing III. Application to liver assessment.

We used the previously described [Clin. Chem. 19, 1114 (1973)] and evaluated [Clin. Chem. 19, 1122 (1973)] computer-controlled instrument system for sequential chemical testing to select and perform tests of hepatic status, to aid the clinician in the diagnosis of liver disease. Results for total bilirubin, aspartate aminotransferase, and alkaline phosphatase obtained from the continuous-flow analysis (SMA 12/60) admission screen were used by the instrument system to determine selectively the values for gamma-glutamyltransferase, alanine aminotransferase, creatine kinase, and total and direct bilirubin. Kit methods for the latter four tests were evaluated on the system; results were similar to manual procedures. A software, enzymatic ratemeter was found to be better than the previously described hardware ratemeter. The follow-up tests of serum prescribed by the system are compared to clinician-prescribed follow-up tests and discharge diagnoses. In 10 of 19 cases, the system and clinician ordered similar follow-up tests; in three cases follow-up differed, and in six cases, the system ordered follow-up tests and the clinician ordered none.

Adult↗
PubMed1977

Enzyme-selective detector systems for high-pressure liquid chromatography.

This paper describes the performance of absorbance and fluorescence detectors in two configurations of post-column reactors for selectively detecting and quantitating isonenzymes eluted form a high-pressure liquid chromatography column. Superb resolution of the isoenzymes of lactic dehydrogenase is illustrated by the use of new ion-exchange materials.

Chromatography, High Pressure Liquid↗
PubMed1976

Computer-assisted differential diagnosis of laboratory abnormalities and follow-up testing. Evaluation of the accuracy of a computer program.

An evaluation is made of a computer program which generates a differential diagnostic list given a set of input data obtained from an admission chemistry screening profile. The program is tested by supplying input data on patients for whom diseases are known. The laboratory data from 367 patients are examined. Accurate computer diagnosis is obtained in many disease categories. The original computer program is modified to suggest the follow-up tests indicated based on the diagnoses it makes. By using this program and some additional clinical input from the physician, the clinical pathologist can select the most appropriate computer diagnosis and begin the follow-up testing. Accelerated diagnosis and patient care should result.

Aged↗
PubMed1976

Automated separation and measurement of lactate dehydrogenase isoenzymes.

We describe a totally automated, computer-controlled system for separating and measuring the activity of lactate dehydrogenase (EC 1.1.1.27) isoenzymes. These isoenzymes in tissue extracts were separated on disposable DEAE-cellulose mini-columns. Resolution was complete except that LD-1 was not resolved from LD-2.

Autoanalysis↗
PubMed1975

Computer-controlled automation of radioimmunoassay based on gel entrapment of antibody.

We describe a new, broadly applicable approach to radioimmunoassay. Solid-phase binding reagent is prepared by entrapping antibody in polyacrylamide gel. This gel is then fragmented, sieved, and dehydrated in 95 percent ethanol. Upon evaporation of the ethanol, the dry antibody-gel particles are dispensed into miniature disposable plastic columns. A unidirectional flowing stream configuration is used to construct a standard curve for the polypeptide hormone, angiotensin I, used here to exemplify the technique. Good reproducibility of this standard curve is demonstrated. The analytical system includes a computer-controlled sample turntable, digital pipet, and liquid-switching assembly.

Acrylamides↗
PubMed1975

A versatile temperature-controlled reaction cuvet.

A thermostatted reaction cuvet, operating under computerized or manual temperature control in the ultraviolet or visible region, is described and evaluated. The cell was designed for use with the automated chemistry system described earlier [Clin. Chem. 19, 1114 (1973)], but can readily be adapted for other applications. The entire 3-ml cuvet assembly warms from ambient temperature to 37 degrees C in less than 10 min, with plus or minus 0.15 degrees C stability; the long-term stability is plus or minus 0.05 degrees C; temperature recovery time after washing or reagent addition is less than 3 min. The optical pathlength is 10.00 mm and the carryover volume is 18 mu-l.

Alanine Transaminase↗
PubMed1975

Trend detection in control data: optimization and interpretation of Trigg's technique for trend analysis.

A method for trend detection, Trigg's technique [Oper. Res. Q. 15, 271 (1964)], has been investigated for use in monitoring trends in control data produced by multitest continuous-flow analyzers. Simulated trend data were used to optimize the method. Actual control data were analyzed retrospectively to determine the frequency of trends and the accuracy of several parameters obtained from Trigg's method. The prospective use of the technique has successfully uncovered important trends. Criteria for the interpretation of the Trigg's trend data are suggested and an algorithm for the computer implementation of Trigg's calculations is included.

Autoanalysis↗