PubMed Health⌕ Search

Biomedical subjects

C A Burtis

Publications and source records attributed to C A Burtis.

At least 19 recordsLinked to original sources
PubMed1996

Converging technologies and their impact on the clinical laboratory.

Rapid technological change is transforming the world in which we live. Because laboratory services are defined by available products and tools of technology, this "technological revolution" is having a significant and profound effect on how clinical laboratories are organized, staffed, equipped, and operated. In this review, I discuss individually and collectively the advances and developments being made in the general areas of measurement, digital, communication, and transportation technology and demonstrate how the convergence of the products evolving from these technologies is affecting the clinical laboratory.

Clinical Laboratory Techniques↗
PubMed1995

Technological trends in clinical laboratory science.

OBJECTIVE: This article will review the advancements and new developments being made in (1) advanced computers, (2) microtechnology, (3) advanced immunodiagnostics, (4) neural networks, and (5) molecular biology. The influence of these technologies and their products on clinical laboratories is also discussed. CONCLUSION: Significant evolutionary and revolutionary technological changes are occurring in a number of scientific and engineering disciplines that impact the medical profession. As a consequence of this era of rapid change, the discipline of Clinical Laboratory Science is undergoing a "technological explosion" which is having a significant and profound effect on how clinical laboratories of today and tomorrow are and will be staffed, equipped, and operated.

Chemistry, Clinical↗
PubMed1992

Design and evaluation of an anti-evaporative cover for use with liquid containers.

We have designed an anti-evaporative cover for use with the sample and reagent cups and other liquid containers that are required in automated analytical systems. This cover, which is simple in design, consists of a baseplate and a cylindrical chimney. By increasing the height and decreasing the inner diameter of the chimney, evaporative losses can be reduced to less than 0.1%/h; thus, aliquots of sample and reagents can be allowed to remain in their cups and containers for several hours before an analytical error due to evaporation will be measurable. We have also modified a model that we previously developed and validated to estimate evaporative losses from open sample cups, to allow us to predict evaporative losses from cups and containers fitted with the new type of cover. This model confirms that the magnitude of the evaporative loss is inversely proportional to the resistance provided by the headspace above the sample in the cup and by the space defined by the chimney of the cover. With chimney heights ranging from 12 to 36 mm and their inner diameters from 1 to 4 mm, greater than 70% of the resistance to evaporation is provided by the cover.

Chemical Phenomena↗
PubMed1990

Sample evaporation and its impact on the operating performance of an automated selective-access analytical system.

In a series of gravimetric and analytical experiments I measured how much analytical error is ascribable to sample evaporation during routine operation of the Dimension analytical system. This error, a time-dependent function, is related to the volume of liquid placed in either a 0.5- or 2.0-mL cup and whether the cup is capped. For the 0.5-mL cups, analytical error at a 4-h residence time ranged from 12% to 16% (uncovered) to 8% to 13% (covered), whereas errors for the 2.0-mL cup ranged from 6% to 10% (uncovered) to 2% to 5% (covered). To minimize evaporative loss, I recommend (a) protecting the surface areas of the samples, (b) using larger samples, and (c) minimizing the time that a sample is in its cup before and during analysis.

Autoanalysis↗
PubMed1987

Statistical considerations of the random selection process in a drug-test program.

In a prospective drug-testing program, individuals whose job classifications have been defined as sensitive are placed in a selection pool. Periodically, individuals are chosen from this pool for drug testing. Random selection is a fair and impartial approach for this because each individual has an equal chance of being selected. Random selection also serves to reinforce the deterrent potential of a drug-testing program because individuals in the pool never know when or if they will be selected. This uncertainty discourages drug usage because of the risk involved in being selected and tested. A random selection process generates a Poisson distribution of probabilities that can be used to predict how many times an individual will be selected during a specific time interval. This information can be used to model the selection part of a drug-testing program to determine whether specific conditions of testing are met. For example, the probability of being selected a given number of times during the testing period can be minimized or maximized by varying the frequency of the sampling process. Consequently, the Poisson distribution and the mathematics governing it can be used to structure a drug-testing program to meet the needs of any given situation.

Employee Discipline↗
PubMed1987

Advanced technology and its impact on the clinical laboratory.

The analytical capabilities of the clinical laboratory have continued to expand and improve as a result of technical developments and advancements made in a wide spectrum of allied disciplines. As a consequence, the clinical laboratory has evolved from the small, manual operations of yesterday to the large, central organizations of today. Technology continues to have an impact on the laboratory, especially with the advent of the fully automated analytical systems that are having such a profound effect on how the laboratory is staffed, equipped, organized, and operated. With the accelerating rate at which new developments are occurring, it is safe to assume that dramatic changes will continue to occur in this area. Consequently, it will become increasingly important for clinical laboratorians to be aware of these new developments, to understand them, and to anticipate how they will be assimilated and integrated into the overall health care system. To quote from a recent Bell Atlantic advertisement, "The genius of the future lies not in technology alone, but in the ability to manage it."

Chemistry, Clinical↗
PubMed1986

Induction of mixed-function oxidase activity in mouse lymphoid tissues by polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbon (PAH) exposure can cause mixed-function oxidase (MFO) enzyme induction in certain tissues of various organisms. Measurement of such induction might serve as a useful bioindicator of human exposure to PAHs, provided readily obtainable human tissues can be utilized for such measurements. We have investigated the MFO activity in various lymphoid tissues of the C3H mouse as a model system and have studied the effect of systemic PAH treatment on such enzyme activity. An MFO enzyme assay was used to measure the activity of 7-ethoxyresorufin deethylase, an enzyme activity that may be specific for the cytochrome P-448 subset of MFO enzymes (those enzymes that are induced in cells or tissues following PAH administration). Intraperitoneal injection of mice with 180 mg/kg (4.6 mg) benzo[a]pyrene (BaP) or 160 mg/kg (4.0 mg) 3-methylcholanthrene (MC) produced a significant induction in MFO activity in mouse spleen S9 fractions 48 h after the injection. Induction ratios (induced activity/control activity) between 4 and 5 were seen with BaP; MC produced induction ratios of 2.5-3.0. Enzyme activity was not induced in the spleen within 16 h following BaP or MC administration. Other experiments indicated that MFO activity could be induced in thymus cells 48 h after either BaP or MC treatment. Treatment with BaP or MC did produce significant enzyme induction in the liver and lung tissues from the animals both 16 and 48 h after chemical treatment.

Animals↗
PubMed1986

Development of a simple device for processing whole-blood samples into measured aliquots of plasma.

A capillary processor and aliquoter has been designed and fabricated that is capable of accepting aliquots of whole blood and automatically processing them into discrete aliquots of plasma. The device consists of two disks, each of which contains 16 individual capillaries and a processing rotor. One disk accepts larger capillaries that hold approximately 100 microL of whole blood each. The second disk accepts 2.54-cm-long precision capillaries of various internal diameters, which provide exact sample volumes from 1 to 10 microL. The processing rotor contains 16 individual compartments and chambers to accept both disks. Applying centrifugal force transfers the aliquots of whole blood into their respective compartments, where they are separated into cellular and plasma fractions. As the rotor speed is slowly decreased, an aliquot of plasma is withdrawn by capillary action into each measuring capillary. The disk containing the 16 measured aliquots of plasma is then removed and placed into a modified rotor for conventional centrifugal analysis. This device can entrain and deliver microliter volumes of liquids with precision and accuracy (1-2%) near that of mechanical pipettes. Assays of the separated plasma aliquots also have acceptable precision (e.g., CVs approximately 3% for measurements of serum enzymes).

Blood Specimen Collection↗
PubMed1983

A reference method for measurement of alkaline phosphatase activity in human serum.

We present an official AACC reference method for the measurement of alkaline phosphatase, the culmination of optimization experiments conducted by a group of independent laboratories. The details of this method and evaluation of factors affecting the measurement are described. A metal ion buffer has been incorporated that maintains optimal and constant concentrations of zinc(II) and magnesium(II) ions. Final reaction conditions are: pH (30 degrees C), 10.40 +/- 0.05; 2-amino-2-methyl-1-propanol buffer, 0.35 mol/L; 4-nitrophenyl phosphate, 16.0 mmol/L; magnesium acetate, 2.0 mmol/L; zinc sulfate, 1.0 mmol/L; and N-(2-hydroxyethyl)ethylenediaminetriacetic acid, 2.0 mmol/L.

Alkaline Phosphatase↗
PubMed1983

Use of laser-excited fluorescence to measure mixed-function oxidase activity.

The microsomal mixed-function oxidase (MFO) system is involved in the metabolism of various chemical compounds. Polycyclic aromatic hydrocarbons are metabolized by the cytochrome P-448 enzyme system, which contains MFOs. Induction of this MFO activity may be useful as an indicator of the toxicity of the inducer material. We have successfully used a portable centrifugal analyzer equipped with an argonion laser light source to quantify cytochrome P-448 activity induced in mouse-liver microsomes by exposing the animal's skin to different doses of liquids derived from a coal-liquefaction process. The MFO activity was determined kinetically by measuring the rate at which the highly fluorescent compound, resorufin, produced by the oxidation of 7-ethoxyresorufin substrate, was formed. The 514.5-nm laser excitation beam was directed with a fiber-optic bundle from the laser to the cuvets of a specially designed rotor; emitted fluorescence was monitored at 90 degrees to the incident beam through a 560-nm cut-on secondary filter. Use of the laser excitation source allowed very low MFO activities to be measured: picomole quantities of resorufin could be determined. We anticipate that the increased sensitivity of the method described here will allow MFO activities to be determined in body fluids and skin.

Animals↗
PubMed1982

The development and evaluation of a homogeneous immunoassay for the isoenzymes of aspartate aminotransferase.

Purified isoenzymes of aspartate aminotransferase (AST) from human liver (mitochondrial) and erythrocytes (cytoplasmic) were used to elicit antisera in rabbits. Each antiserum was characterized for titer and specificity. Complexes formed upon addition of each isoenzyme to its specific antiserum were demonstrated to be catalytically inactive. Results obtained when either filtration or centrifugation was used for separating the complexes (heterogeneous assay) were comparable to those obtained when the complexes were not separated (homogeneous assay) from the mixture before assay. A quality control system was designed to monitor specificity in addition to the usual parameters. The precision for the inhibition of cytoplasmic (CV 4.8%) and mitochondrial (CV 3.5%) isoenzymes was within that of the enzymatic assay. Several parametric conditions of the enzyme-antibody reactions were examined, and the assay was adapted for semi-automation. The homogeneous assay was evaluated with a series of pseudo specimens containing known mixtures of pure isoenzymes to determine the extent of recovery (99.8%) for a particular isoenzyme in the presence of varying concentrations of the other isoenzyme. In addition, sera from patients having elevated AST concentrations were examined for isoenzyme contributions to total AST activity. A mean recovery of 96% was obtained for these specimens.

Antibody Specificity↗
PubMed1980

An interlaboratory study of the determination of digoxin by immunoassay.

We conducted a voluntary survey of laboratories and manufacturers to assess the current quality of analytical assays for serum digoxin. More than 300 clinical laboratories and 18 manufacturers responded, giving data on methods, instruments, computational procedures, and results for five survey samples. We sorted the analytical data to provide statistical information on the grand mean values separately for manufacturers and clinical laboratories, the frequency distribution of all reported values, and the mean values by method of interpolation and algorithms used for linear transformation. There was no statistical difference (alpha = 0.05) between the means for each specimen as determined by the kit manufacturers as a group and the clinical laboratories as a group.

Digoxin↗
PubMed1980

A coupled-enzyme equilibrium method for measuring urea in serum: optimization and evaluation of the AACC study group on urea candidate reference method.

We describe a coupled-enzyme equilibrium method for measuring urea in serum, which is performed on supernates prepared by treating each specimen with Ba(OH)2 and ZnSO4 (Somogyi reagent). Analytical recovery of [14C]urea added to a variety of matrices was essentially complete (mean, 100.6%) for the supernates after precipitation. Nine variables were univariately examined in arriving at the reaction conditions for the method: glutamate dehydrogenase, urease, 2-oxoglutarate, ADP, Tris . HCI, NADH, EDTA, pH, and temperature. The reagent is stable for at least 48 days at--20 degrees C and for 23 days at 4 degrees C. Mean analytical recovery of urea (14 mmol/L) added to seven different specimens (three different matrices) was 100.8%. The analytical linear range of the method extends to 30 mmol of urea per liter. Of 22 potential interferents, only bilirubin at 1 mmol/L (580 mg/L), hemoglobin at 10 g/L, and hydroxyurea at 6 mmol/L showed more than 2% interference. We discuss precision and effects of specimen dilution, and compare results for 100 human serum specimens with those measured for the same specimens with four other urea methods. We examined the effects of measuring a blank, consisting of sample and reagent without urease, with each specimen.

Animals↗
PubMed1979

Determination of free, total, and esterified cholesterol by high-performance liquid chromatography.

A method is described for measuring free, total, and esterified cholesterol in blood serum in which reversed-phase liquid chromatography is used and the eluate is monitored at 200 nm. The sample for total cholesterol is prepared according to the Abell-Kendall procedure, and for free cholesterol an extract of serum--isopropanol (1:5, v/v) is used. The column is a muBondapak C18, 10 micrometers, and the mobile phase for total cholesterol is isopropanol--acetonitrile (50:50, v/v); for free cholesterol, it is isopropanol--acetonitrile--water (60:30:10). An approximation of the free cholesterol, triglycerides, and individual cholesteryl esters is obtained from single chromatograms of isopropanol extracts of serum if the first mobile phase is used. In a comparison study with the Abell-Kendall method for total cholesterol, the correlation is excellent and the precision is acceptable.

Cholesterol↗