Adding value to proficiency testing programs.
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Biomedical subjects
Publications and source records attributed to R N Carey.
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BACKGROUND: Adverse reactions to foods are encountered much less frequently in adults than in the children. Adult onset hypersensitivity to grapes has not been previously reported. OBJECTIVE: Evaluation of a case of anaphylaxis that occurred as a result of the consumption of white grapes (Vitis vinifera). METHODS AND RESULTS: A 28-year-old woman experienced generalized urticaria, facial/oropharyngeal angioedema, and dizziness after eating a bunch of white grapes. She was treated in an emergency room for anaphylaxis. Previously, she had experienced two similar episodes after eating white grapes. The grape prick skin tests were strongly positive forming a pseudopod type reaction. The total serum IgE was 1918 ng/mL. The grape-specific serum IgE was weakly positive by the modified RAST and negative in the Pharmacia-Upjohn Cap System. CONCLUSION: Hypersensitivity to a commonly consumed fruit such as grapes can develop late in life causing a near-fatal anaphylaxis.
An assay for hepatitis B surface antigen (HBsAg) should reliably detect 0.2 microgram/L, the lowest reported concentration in an asymptomatic blood donor. The difference between this concentration and the assay cutoff defines the analytical quality requirement in a total error format. The design of a statistical QC procedure is critically dependent on the precision of the assay. The precision of a developmental ELISA of HBsAg under study ranged from 17.5% to 9.6% for controls containing 0.07 to 1.50 micrograms/L, respectively. Use of one positive control with the 1(3s), QC rule provided an 85% chance of detecting a critical loss of assay sensitivity; use of two positive controls increased the chance of detecting critical loss of assay sensitivity to nearly 100%. These rules are based on the precision of this developmental assay, and must be developed individually for other assays. The development of the proposed QC procedures illustrates how quantitative QC can be provided for qualitative assays.
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Although CLIA 88 has probably caused the laboratorian to place inordinate emphasis on proficiency testing, we believe that it will ultimately improve clinical laboratory practice. Due to the increased numbers of challenges within a mailing, the laboratorian has a greater ability to gauge magnitudes and types of any existing error. These magnitudes can be compared with previously established limits to determine the need for corrective action. Laboratories are encouraged to devise a system to guarantee accurate preanalytic, analytic, and postanalytic PT processing and reporting. Due to the relatively low imprecisions of today's hematology analyzers compared with the HCFA limits, most hematology laboratories should focus their attention on measures of and factors affecting long-term control and calibration. More attention should be paid to moving averages of indices and the analytic performance in regional or manufacturer control pools.
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Multirule quality control procedures employ combinations of individual quality control rules to increase the probability of error detection without increasing the probability of false rejections to unacceptable levels. Performance characteristics of several example multirule procedures are described, and general recommendations are made for their selection and use. Multistage quality control procedures tailor the control rules employed to the frequency of errors expected during a given phase of analyzer operation. During analyzer startup, sensitive rules are employed; after acceptable analyzer performance is demonstrated, less sensitive rules are used for routine monitoring. As they tend to deteriorate quality control rule performance, between-run variations should be minimized.
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A 66-year-old man with an 18-year history of cutaneous multicentric reticulohistiocytosis (MRH) developed a chronic destructive symmetrical arthritis and xerostomia. Biopsies of synovium and minor salivary glands established a diagnosis of MRH polyarthritis and lymphocytic infiltrative Sjögren's syndrome, respectively. Anti-Ro(SSA) antibody was present. Hypothyroidism was also identified. This report of Sjögren's syndrome in MRH may enlarge the spectrum of autoimmune diseases associated with MRH.
The activity of an isoenzyme of alkaline phosphatase (FHAP) was measured in serum samples obtained from 1692 individual subjects. The median FHAP concentration in patients with untreated or recurrent cancer (2.73 IU/liter) was two-fold higher than in hospitalized control patients with illnesses other than cancer (1.17 IU/liter) and three-fold higher than in healthy control subjects (0.93 IU/liter). Among patients with either breast or colorectal cancer who were clinically disease free following their initial therapy, the median FHAP concentration (1.54 IU/liter) was intermediate between the median FHAP concentration in patients with untreated or recurrent cancer and that of healthy control subjects. In order to illustrate the potential clinical application of FHAP as a diagnostic cancer marker, we have selected a serum FHAP concentration of 2.22 IU/liter as a reference value above which only 3% of healthy control subjects would have a "positive" test. Utilizing this reference value, 58% of the patients in the present study with untreated or recurrent cancer would have a positive FHAP test, whereas only 11%, of hospitalized patients with illnesses other than cancer would have a positive test. These data suggest that FHAP may be equivalent to the carcinoembryonic antigen as a diagnostic cancer marker.
The authors examined both hard and soft glass evacuated blood-drawing tubes for possible effects on clinical chemistry measurements. Using routine laboratory procedures, no clinically or statistically significant difference could be detected in 34 analytes using 66 different methods. A special high-precision study utilizing an adaption of the NBS round-robin procedures for calcium, magnesium, sodium, and potassium detected no difference between paired sera when drawn or stored for 72 hours, or both, in the two types of glass. The authors conclude that the type of glass used in production of the evacuated blood-drawing tubes does not affect the clinical chemistry results obtained.
Protein activation of urinary alpha-amylase (EC 3.2.1.1) activity was observed during an evaluation of the Du Pont aca procedure for the determination of urinary alpha-amylase. This activation effect became constant for urinary albumin concentrations exceeding 1.50 g/liter. It is recommended that urinary alpha-amylase be analyzed with sufficient albumin added to maximize this effect. The aca alpha-amylase procedure is compared to an amyloclastic method for both serum and urine analysis. Expected ranges are presented for the aca method for serum and urinary amylase, amylase clearance, and the amylase clearance/creatinine clearance ratio.
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We assessed the analytical performance of the co-immobilized hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) method for D-glucose analysis on the Technicon SMAC. The enzyme-containing coils were usable for one month, or 12 000 tests. Bilirubin, hemoglobin, lipemia, creatinine, uric acid, citric acid, and ascorbic acid did not interfere. Results with this method were compared to those by the National Glucose Reference Method. The upper limits of the total error estimate (a combination of random and systematic errors) were 76, 74, and 125 mg/liter at concentrations of 500, 1200, and 3000 mg/liter, respectively. The error estimates were less than allowable errors based on medical usefulness; thus the method was judged to perform acceptably with respect to the Reference Method. We also present performance data for the routine SMAC glucose oxidase (EC 1.1.3.4)/Peroxidase (EC 1.11.1.7) 3-methyl-2-benzothianolinone hydrazone-N,N-dimethylaniline method, the direct hexokinase method with the Du Pont aca, and the glucose oxidase oxygen-rate method with the Beckman Glucose Analyzer.
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