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PubMed2004

Comparison of the ADVIA Centaur and Abbott AxSYM immunoassay systems for a routine diagnostic virology laboratory.

BACKGROUND: Routine diagnostic laboratories are confronted with an ever-increasing workload with limited resources. Automation has provided some solutions to these challenges particularly high through put analysers such as the Abbott AxSYM. OBJECTIVE: The aim of the present study was to compare the performance of two automated immunoassay systems in a diagnostic virology laboratory. Samples previously tested using the Abbott AxSYM were tested with a recently introduced immunoassay analyser, the Bayer ADVIA Centaur, for six virology analytes: HBsAg, anti-HBc total, anti-HBc IgM, anti-HBs, anti-HCV and anti-HIV1/O/2. STUDY DESIGN: This study was a retrospective analysis of stored serum samples previously tested on the Abbott AxSYM. Samples giving discrepant results were tested by other alternative immunoassays and re-tested on the Abbott AxSYM in the same freeze-thaw cycle. RESULTS: Although the sensitivities of the two automated immunoassays were similar there was improved specificity demonstrated for anti-HIV and anti-HCV when using the ADVIA Centaur assays. The low background signals allowed resolution of samples previously shown to have indeterminate results for anti-HIV antibody in the AxSYM assay. In addition, samples shown to have Abbott AxSYM anti-HCV results that could not be confirmed by RIBA and HCV molecular methods were shown to be negative by the ADVIA Centaur assay.

AIDS Serodiagnosis↗
PubMed1980

Automated pharmaceutical assistance systems. I. Clinical pharmacokinetics. II. Drug interference with laboratory tests results.

The function of the clinical pharmacokinetic service (CPS) in University Hospital is described. A methodological procedure was developed for routine interpretation of specified drug serum levels. Work lists that identify analytical procedures to be included for clinical pharmacokinetic evaluation are prepared daily. The results of all analyses of serum drug levels are evaluated by a pharmacist who is trained in clinical pharmacokinetics. Patient variables that influence serum levels of drugs are mathematically manipulated by program logic. Projections of expected drug levels as a result of dosing regimens are made and compared to measured laboratory results. Iterative programming that modifies projections on the basis of actual measurements is employed to determine individual drug dosing regimens that provide therapeutic/nontoxic serum levels of drugs. The drug/test interference system, which accesses the CPS data base, provides information concerning the potential physiologic, therapeutic, or toxic effect of drugs on biochemical substances. The system allows display of data concerning each drug before it is administered. Information concerning the date and time of initiation and termination of drug therapy allows for a warning comment to be attached automatically to the appropriate laboratory test result if interference is indicated.

Computers↗
PubMed1975

Semi-automated ECG processing: A simple method to improve efficiency in ECG laboratories.

A method to expedite processing of electrocardiograms (ECGs) is described. The hardware configuration utilizes conventional equipment, and the ECG data is stored in magnetic data cards. The electrocardiographer's interpretation is made using a specially developed code of 253 diagnostic statements of 2 to 9 words each. A minicomputer converts the code into full alpha-numeric description and 2 characters into English statements. The diagnostic print-out appears in the same page as the reproduction of the original ECG data. This system has significantly reduced the ECG processing time, freed manpower to increase availability of technicians and decreased the size of permanent files.

Diagnosis, Computer-Assisted↗
PubMed1998

Controlled clinical laboratory comparison of two supplemented aerobic and anaerobic media used in automated blood culture systems to detect bloodstream infections.

A 20-ml blood sample was collected from adult patients with suspected bloodstream infections and distributed equally into the four volume-controlled bottles of a blood culture set consisting of aerobic and anaerobic BACTEC Plus/F bottles and aerobic and anaerobic BacT/Alert FAN bottles. All bottles were incubated in their respective instruments for a standard 5-day protocol or until the instruments signalled positivity. Samples in all bottles with negative results by these instruments were terminally subcultured. A total of 8,390 blood culture sets were obtained during the study period, of which 4,402 (52.5%) met the study criteria. Of these, 946 (21.5%) were positive either by instrument signal or by additional terminal subculture of all negative bottles and yielded growth of microorganisms. Five hundred eighty-nine (13.4%) blood culture sets were considered to have recovered 663 clinically significant organisms. When both the BACTEC and the BacT/Alert systems were used, 465 positive sets were detected; BACTEC alone detected 52 positive sets and BacT/Alert alone detected 72 (P = 0.09). No differences were found between the two systems in microbial recovery rate from blood cultures obtained from patients on antibiotic therapy. Significantly more members of the family Enterobacteriaceae (P < 0.01) were detected from patients without antimicrobial therapy by BacT/Alert than by BACTEC. The false-negative rates were 0.20% for BACTEC and 0.32% for BacT/Alert. A significantly higher false-positive rate was found for BACTEC (P < 0.0001). Both systems were comparable for the time to detection of microorganisms. However, gram-positive bacteria were detected faster by BACTEC and Enterobacteriaceae were detected faster on average by BacT/Alert. We concluded that both systems are comparable in their abilities to recover aerobic and anaerobic organisms from blood cultures and a terminal subculture might not be necessary for either of the two systems. The increased positivity rate when using an anaerobic bottle in a two-bottle blood culture set is due to the additional blood volume rather than to the use of an anaerobic medium.

Adult↗
PubMed2001

Novel test and its automation for the determination of erythrocyte acetylcholinesterase and its application to organophosphate exposure.

BACKGROUND: Because of the lack of a problem-free, reliable method for determination of erythrocyte acetylcholinesterase (AChE), we developed a simple kinetic method, which we found to be both reliable and suitable for automation in the routine clinical laboratory. METHODS: Acetylthiocholine, used as substrate, is hydrolysed by acetylcholinesterase to yield acetate and thiocholine. Thiocholine reacts with dichlorophenolindophenol, a blue coloured compound, which is reduced to a colourless product, producing a linear decrease in absorption at 606 nm. If required, this assay can also be run at 600 nm with equally acceptable results. RESULTS: The method was automated on the Synchron LX20 multianalyser (Beckman Instruments) and blood samples of 80 patients with clinically symptomatic organophosphate poisoning and 153 normal controls were evaluated. Acetylcholinesterase values were in the range of 0-14 UgHb(-1) in cases of organophosphate poisoning, in contrast with normal controls, who had AChE values of 24.4--37.9 UgHb(-1). No overlap was found between AChE values of controls and poisoned cases. Intra- and inter-assay coefficients of variation were 1.68 and 3.71%, respectively. CONCLUSION: The method we propose for measurement of AChE was found to be simple, reliable and easily automatable in the routine clinical laboratory.

2,6-Dichloroindophenol↗
PubMed1989

Clinical biochemistry in Singapore.

During the period from 1982 to mid-1989, there has been very significant changes and improvement in the practice and application of clinical biochemistry in Singapore. This paper highlights recent developments in the repertoire of biochemical analyses, utilisation of laboratory tests, biochemical screening in preventive health care, handling and delivery of patient specimens, advances in analytical techniques, automation, computerisation, quality assurance, training of laboratory personnel, and professional activities. It also draws attention to the restructuring of the Singapore General Hospital and the government Department of Pathology which frees these government institutions from the constraints of the civil service so that they would be sufficiently flexible to respond readily to the changing needs and expectations of the patients and users of laboratory services. This is the most prominent event and policy change in the history of health care services in Singapore that is expected to result in more cost-effective utilisation of resources and greater improvement in the quality of health care.

Automation↗
PubMed2003

Determination of thiopurine S-methyltransferase activity in erythrocytes using 6-thioguanine as substrate and a non-extraction liquid chromatographic technique.

A non-extraction high-performance liquid chromatographic (HPLC) method has been developed for the determination of 6-methylthioguanine (6-MTG), as part of the determination of thiopurine S-methyltransferase activity (TPMT) in erythrocytes. Erythrocyte lysate is added to a glass vial containing substrates and incubation buffer, which is then sealed for the rest of the analysis. Enzyme incubation, sample preparation, and analysis are then undertaken without further sample-handling steps. The need for a solvent extraction step has been overcome by heating the incubate to 85 degrees C to stop the enzyme reaction. The heat inactivation step precipitates protein which upon centrifugation forms a thin film in the bottom of the glass vial enabling the supernatant to be injected directly onto the HPLC system. The assay shows excellent precision and recovery with a within-batch imprecision giving a co-efficient of variation of 2.9% (mean=41.5 nmol 6-MTG/gHb/h, n=10) and 5.1% (mean=12.6 nmol 6-MTG/g Hb/h, n=10). The between-batch imprecision gives a co-efficient of variation of 8.2% (mean=11.1 nmol 6-MTG/gHb/h, n=11) and 7.3% (mean=41.0 nmol 6-MTG/gHb/h, n=16). Determination of the TPMT activity in 120 people shows a range of enzyme activity of 11.3-63.8 nmol 6-MTG/gHb/h with a mean and median activity of 34.8 and 34.2 nmol 6-MTG/gHb/h, respectively. TPMT is increasingly used in clinical practice to ensure optimisation of treatment with thioguanine drugs. This direct HPLC method minimises sample-handling, reduces inherent imprecision, the possibility of laboratory error and with the potential for further automation, makes it ideal for use in a regional referral laboratory.

Chromatography, High Pressure Liquid↗
PubMed2000

Computer-automated clinical technique for tinnitus quantification.

This study addresses the need for uniformity in techniques for clinical quantification of tinnitus. Because automation can be an effective means to achieve standardization, this laboratory is developing techniques to perform computer-automated tinnitus testing. The present study was conducted to demonstrate the feasibility of obtaining reliable tinnitus measures using a fully automated system. A computer-controlled psychoacoustical system was developed to quantify tinnitus loudness and pitch using a tone-matching technique. Hearing thresholds were also obtained as part of the procedure. The system generated test stimuli and simultaneously controlled a notebook computer positioned in the sound chamber facing the patient. The notebook computer displayed instructions for responding and relayed response choices through on-screen "buttons" that the patient touched with a pen device. Twenty individuals with tinnitus were evaluated with the technique over two sessions, and responses were analyzed for test-retest reliability. Analyses revealed good reliability of thresholds, loudness matches, and pitch matches. These results demonstrate that use of a fully automated system to obtain reliable measurements of tinnitus loudness and pitch is feasible for clinical application.

Adult↗
PubMed1982

Methodological considerations on chromogenic peptide substrate assays and application on automated analyzers.

Chromogenic peptide substrates (CPS) are small peptides with the chromophore p-nitroaniline (pNA) coupled to the terminal carboxyl group in an amide linkage. These substrates are the basis for a new generation of analyses of serine proteases. A short review of established manual methods for determination of key components of the plasma proteolytic enzyme systems as well as other serine proteases is given here. The enzymatic cleavage of the peptide-pNA amide linkage in CPS results in release of pNA. This reaction can be monitored at 405 nm in a spectrophotometer and can easily be automated using equipment found in most clinical chemistry laboratories. In our laboratory we have adapted such assays to the LKB 8600 automated reaction rate analyzer and the Cobas Bio centrifugal analysis system. Using these machines, we have established methods for the determination of proenzymes, protease-alpha 2M complexes and functional inhibitor capacities of several serine protease systems. With these automated assays a rapid system for close monitoring of the coagulation, fibrinolytic and plasma kallikrein-kinin systems in various disease states has become available.

Autoanalysis↗
PubMed1994

An analysis of response to nicotine infusion using an automated radiotelemetry system.

Previous studies from our laboratory have demonstrated that chronic nicotine infusion evokes tolerance to nicotine injected IP several hours after withdrawal from chronic infusion. This method may introduce problems related to withdrawal reactions and to stress associated with handling of the animals. The studies reported here measured tolerance to nicotine in mice using an automated radiotelemetry system. DBA/2 mice were infused intravenously with saline for 4 days followed by infusion of a 4 mg/kg per h dose of nicotine for 7 days. After the nicotine treatment, the mice were infused with saline for 7 days. The nicotine was infused continuously or in four 1 mg/kg pulses, two 2 mg/kg pulses or one 4 mg/kg pulse each hour. Home cage activity and body temperature were measured throughout the treatment periods using a radiotelemetry system. Nicotine infusion produced an abrupt decrease in body temperature and activity, but this effect was totally reversed within 12 h in the continuously infused and four infusions/h treatment groups. Mice that received one or two infusions/h also showed a rapid response to nicotine that was reversed as treatment proceeded, but nicotine continued to produce a measurable effect for several days. After nicotine withdrawal, temperature and activity returned to predrug infusion values in all of the groups except those infused once per hour. This group showed depressed activity for a minimum of 3 days after nicotine treatment stopped. Thus, the kinetics of nicotine administration affected the intensity of response during continued treatment as well as activity after cessation of chronic treatment.

Animals↗
PubMed1998

Hepatitis C genotyping by direct sequencing of the product from the Roche AMPLICOR test: methodology and application to a South Australian population.

The Roche AMPLICOR RT-PCR amplifies a 244 nucleotide sequence within the 5' non coding region (5'NCR) of the viral genome and is a widely used commercial test for the qualitative determination of hepatitis C RNA from sera. This paper describes a routine procedure for the purification of the PCR product, and its use in automated DNA sequencing, for determining the genotype of hepatitis C virus (HCV) isolates. Direct sequencing of the purified product was possible for 86% of samples, whilst 14% required additional amplification using a nested PCR method in order to read the resulting electropherogram. This method of genotyping is considerably less expensive than currently available commercial kits, and is convenient for the increasing number of laboratories that have access to automated DNA sequencers. The highly conserved nature of the 5'NCR limited differentiation of types and subtypes to an extent comparable to commercial HCV typing methods. Using this method on available laboratory samples and on patients about to commence interferon therapy, we found a predominance of genotype 1 (59%) and 3a (31%). Analysis of data on the interferon patients showed the median length of time from first exposure to diagnosis to be significantly longer for patients with genotype 1 than genotype 3a.

Adult↗
PubMed1999

Test facility for human exposure to AC and DC magnetic fields.

For more than a decade, Midwest Research Institute (MRI) has investigated the effects of exposure to 60 Hz electric and magnetic fields (EMF) on human physiology, performance, and biochemistry. This accumulated experience, new research directions, and limited resources made it important to design more comprehensive and operationally cost-effective exposure facilities. Here we describe the new, integrated laboratory exposure test facilities recently constructed at MRI and present data on relevant characteristics of the exposure systems. Concentric coil systems were developed to generate uniform magnetic fields within the three new exposure rooms, with rapid cancellation of the field to ambient levels in the rest of the laboratory. Control systems are fully automated, computer-based, and independent. These provide the operational flexibility needed to present fields of different magnitudes, frequencies, and polarization. The local geomagnetic field can be modulated and/or canceled, and both AC and DC fields can be presented in various combinations. Capabilities for conducting double-blind experiments with true active-sham exposure conditions were implemented using bifilar windings and applying current flow in the opposite direction for each wire in a pair. The new facilities provide a comprehensive capability for laboratory-based human research on the potential effects of exposure to AC and DC magnetic fields.

Automation↗
PubMed2006

Testing automated liquid-based cytology samples with a manual liquid-based cytology method using residual cell suspensions from 500 ThinPrep cases.

We report a technical improvement upon a previously disclosed manual liquid-based cytology (MLBC) method; and, we use the improved method to prepare slides from residual ThinPrep specimens in order to see how often ThinPrep diagnoses correspond to diagnoses derived from exhaustive examination of their parent sample suspensions. Residual cell suspensions from 500 ThinPrep cases comprising (1) 20 low-grade squamous intraepithelial lesions (LSILs); (2) 200 high risk (HR) negatives and 20 ASC-US; and (3) 260 screening cytology specimens were studied. Institutional review committee guidelines allowed us to know diagnoses by groups of specimens, but did not allow us to know individual patient diagnoses, so we could not perform case-by-case matched outcome-comparisons. Cells were concentrated by conventional centrifugation and sedimented into a polymer gel that was then vortex-mixed and converted into a viscous cell-rich suspension. The cell suspension was smeared between two clean glass slides, which were air-dried and stained with the Papanicolaou stain. Two study-sets were created, comprising one slide from each case. Each of the two study sets was examined by two cytopathologists, and discordant diagnoses were adjudicated. Because of the ambiguity involved in the "atypical" (ASC-US, ASC-H, AGC) diagnosis categories, only outcomes at the level of LSIL or greater were recorded. All MLBC SILs were digitally imaged and abnormal slides plus digital images were sent to the laboratory that provided the residual automated liquid-based cytology (ALBC) suspensions. The final diagnoses were confirmed by the laboratory that provided the residual ALBC specimens. MLBC slides of the 20 LSIL cases afforded 2 high-grade squamous intraepithelial lesions (HSILs) and 18 LSILs. Those of the 200 HR-Negatives showed 3 HSILs and 30 LSILs; and those of the 20 HR-ASC-US showed 3 HSILs and 9 LSILs. MLBC slides of the 260 screening cytology specimens showed 1 Carcinoma, 3 HSILs and 20 LSILs; affording 3 HSILs and 14 LSILs more than originally diagnosed. The MLBC method of this report is useful for preparing cell suspensions for cytological examination. Our analytical method was exhaustive and used nearly all of the cell material that was provided to us for analysis; therefore, we conclude that this approach is useful for determining how well ALBC instruments represent their parent sample suspensions. It appears that "rare events" may be overlooked when limited sample aliquots are analyzed by ALBC instruments, and this probably accounts for our increased discovery of SILs by the MLBC method. Also, SILs often present as aggregates of cohesive cells which, if overlooked or ineffectively transferred to ALBC slides, would not be diagnosed.

Cytological Techniques↗