Optimized kinetic glutamate dehydrogenase assay adapted to the Cobas Bio centrifugal analyzer.
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Animals↗
Biomedical subjects
D A Armbruster
Publications and source records attributed to D A Armbruster.
Rat liver pyruvate carboxylase. Inhibition by chromium nucleotide complexes.
The effect of inert coordination complexes of chromium (III) with various nucleotides on the catalytic activity of rat liver pyruvate carboxylase was determined. The chromium nucleotides are effective initial inhibitors of pyruvate carboxylase and the inhibition becomes more severe with time. The initial rate decreases for several minutes, reaching a new slower rate that is then maintained until considerable net reaction occurs. Incubation of the enzyme with chromium nucleotides in the presence of Mg2+ and HCO3- causes maximal inhibition of the reaction and linear initial rates are then observed. This effect is similar to that found with yeast hexokinase (Dannenberg, K.D., and Cleland, W.W. (1975) Biochemistry 14, 28-39). The specificity of the carboxylase toward the nucleotide complexes suggests that the alpha and beta nucleotide phosphates are as important as the gamma phosphate in binding to the enzyme. A stable pyruvate carboxylase chromium nucleotide complex was not observed. These results are quite different from those found with yeast hexokinase where a stable complex between CrATP, sugar, and enzyme is found and hexokinase appears to be specific toward the beta, gamma phosphates of its nucleotide substrates.
Adenosine Diphosphate↗
Screening for drugs of abuse with the Roche ONTRAK assays.
A family of manual, qualitative, latex agglutination inhibition immunoassay screening tests (ONTRAK, Roche) for amphetamines, barbiturates, cocaine, marijuana, morphine, and phencyclidine were evaluated. The assays are inexpensive, rapid, portable, and easy to perform, requiring little training to obtain proficiency. The tests are sensitive to drug concentrations at or around the stated cutoff values. The ONTRAK results agree well with the results obtained from fluorescence polarization immunoassay (FPIA) or radioimmunoassay (RIA) screening and GC/MS confirmation. Potential drawbacks of the test kits include the subjective nature of the qualitative assays and the lack of a positive control. The ONTRAK system provides a reasonable means of conducting field testing for drugs of abuse.
Costs and Cost Analysis↗
Method comparison of EMIT 700 and EMIT II with RIA for drug screening.
The EMIT 700 and EMIT II assays for marijuana, cocaine, opiates, barbiturates, and phencyclidine, as performed on a Hitachi 717 Analyzer, were compared with Roche Abuscreen RIA tests for high-volume drug abuse screening. The EMIT II kits offer some advantages over the EMIT 700 kits for testing large work loads. The EMIT II marijuana test in particular exhibits a calibration curve that promises improved ability to separate negative from positive samples due to the increased absorbance rate separation between the negative and cutoff calibrators. Both EMIT formulations are preferable in terms of speed and ease of analysis in comparison with our laboratory's current RIA procedures. Over 50,000 urine samples were screened by EMIT 700 and RIA and by EMIT II and RIA. The performance of both EMIT assays was approximately equivalent to RIA in terms of their ability to detect urine samples that confirmed positive for cocaine and opiates. Both EMIT assays detected approximately 90% of the urine samples screened positive by RIA and confirmed positive for marijuana. Both EMIT assays performed better than RIA in detecting confirmed-positive barbiturate samples.
Calibration↗
Hazardous waste disposal and the clinical laboratory.
Negligent, unregulated hazardous waste management has resulted in real and potential threats to public health and safety. The federal government has responded with laws and regulations aimed at the producers of hazardous waste, including clinical laboratories. Clinical laboratory managers must understand how the requirements apply to their facilities and how to comply with them, or risk violating the law. The Resources Conservation and Recovery Act (RCRA) imposes controls on hazardous waste management through the Code of Federal Regulations (CFR). The Environmental Protection Agency (EPA) and the Department of Transportation (DOT) regulate these activities through 40 CFR and 49 CFR, respectively. 49 CFR specifies the characteristics of hazardous waste and lists more than 400 toxic chemicals, including several commonly used in clinical laboratories. Laboratories must conduct chemical inventories to determine if they should obtain an EPA identification number as a hazardous waste generator. Most clinical laboratories can operate satellite accumulation points and accumulate, store, transport, and dispose of waste in accordance with EPA and DOT regulations. Regulations pertaining to infectious waste, sure to affect many clinical laboratories, are being developed now by the EPA. The tracking system mandated by the federal government can be supplemented by state and local authorities and poses a significant regulatory challenge to clinical laboratory managers.
Facility Regulation and Control↗
The OSHA hazardous chemical occupational exposure standard for laboratories.
OSHA's chemical occupational exposure standard for laboratories is an outgrowth of the previously issued Hazard Communication Standard. The standard relieves laboratories from complying with general industry standards but does require compliance with specific laboratory guidelines. The heart of the standard is the creation of a Chemical Hygiene Plan (CHP). The CHP addresses major issues such as safety equipment and procedures, work practices, training, the designation of a chemical hygiene officer, and the provision of medical consultation and examination for affected employees. This new standard, in full effect as of January 31, 1991, presents yet another regulatory challenge to laboratory managers but also ensures a safer environment for laboratory workers.
Hazardous Substances↗
The quintessence of quality in the clinical laboratory.
Providing quality service is the goal of laboratory managers. The quintessence of clinical laboratory quality is the provision of an appropriate service--either medical information or some other service--that can be shown to measurably satisfy a patient's medical need and can be tied to patient outcome. Traditional quality measures, such as laboratory inspections and proficiency testing surveys as used by CLIA'88, are not the optimal yardsticks to apply. More effective programs are needed, such as the CAP's Q-Probes, that link laboratory operations with documented desired patient outcome. Only when a laboratory can define quality in a way that allows it to be quantitatively assessed in terms of patient care can it really know if it is providing optimal service.
Laboratories, Hospital↗
Non-pretreatment digoxin assays and developments in immunoanalyzers.
OBJECTIVE: The performance of a new, non-pretreatment digoxin assay for the Abbott IMx analyzer (Abbott Park IL) was evaluated to determine its reliability and suitability for routine clinical use. The operational characteristics of 1st, 2nd and 3rd generation immunoanalyzers are compared and contrasted. DESIGN: Within-run and day-to-day precision of the assay was determined, as well as its limit of detection. The effect of digoxin-like immunoreactive factors and carryover were evaluated. Serum from patients receiving digoxin was analyzed using the Dade Stratus II (Miami FL) digoxin test as the reference method and the IMx digoxin test as the comparison method. SETTING: An independent reference laboratory specializing in serving long-term care facilities. PATIENT POPULATION: Specimens were analyzed from geriatric patients in long-term care facilities who receive digoxin as a therapeutic drug for cardiac arrhythmias. Specimens were also tested from individuals in this same population, not receiving digoxin but demonstrating the presence of digoxin-like immunoreactive factors. MAIN OUTCOME MEASURE: Comparability of results from a new nonpretreatment digoxin with the standard digoxin assay (Stratus II) was used to determine the suitability of the new test for routine clinical use. RESULTS: The limit of detection is 0.27 ng/mL; day-to-day precision ranges from 3.4% CV to 5.9% CV. Linear regression analysis generated the following equation: IMx = 0.968 Stratus + 0.1043, r = 0.9776, n = 237. No significant interference from digitoxin-like immunoreactive factors was noted. CONCLUSION: The IMx nonpretreatment digoxin assay's performance matches the manufacturer's claims, compares favorably with another common automated digoxin test, and is suitable for routine clinical use.
Aged↗
Some personal reflections on downsizing.
Downsizing, the deletion of jobs and the involuntary termination of the employees occupying those positions, has become a common and accepted corporate management tool. Although it may save money and improve a company's financial balance, it can bring with it various undesirable outcomes, including loss of loyalty and trust of personnel and degradation of the quality of the organization's product, be it a manufactured item or a service. Downsizing, as it is typically practiced, demonstrates a double standard on the part of management. The deference that employees are expected to show to employers typically is not reciprocated by companies. As a result, workers, even well-educated, professional white-collar personnel, cannot take job security for granted and must be prepared to survive a downsizing action. Front line managers usually are tasked with carrying out a downsizing action decided on at the corporate level. It is to their benefit to practice a management style that will allow them to do so in a professional manner, preserving both their credibility and the employee's dignity to the extent possible. The basic concept of downsizing is not invalid, but the manner in which it is implemented often leaves much to be desired.
Employment↗
Reagent lease/rental agreements: an alternative to instrument purchase. Acquire a state-of-the-art analyzer more quickly and easily.
A primary responsibility of the laboratory manager is to obtain analytical instrumentation for his or her facility. Traditionally, analyzers are purchased as capital investments. An increasingly popular alternative is the reagent lease/rental agreement. A manufacturer provides a laboratory with an analyzer with the provision that the laboratory will purchase the reagents from the manufacturer. Reagents are purchased at a set cost per test, which varies with test volume, and this price incorporates a charge for the use of the instrument. The laboratory manager can acquire a state-of-the-art analyzer more quickly and easily than through a purchase and can maintain the flexibility to switch to a more suitable system as technology and service requirements change. Significant advantages and disadvantages accrue to both the laboratory and the manufacturer. The reagent lease/rental agreement is an option definitely worth considering by laboratory managers.
Autoanalysis↗