bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limitations of Proficiency Testing Under CLIA '67
Authors: Laessig R H , Ehrmeyer S S , Lanphear B J , Burmeister B J , Hassemer D J 
Published: January 2020

Abstract
Proficiency testing (PT), recognized as a quality-assurance (QA) and quality-improvement tool, also has become the cornerstone of the Health Care Financing Administration's (HCFA) regulatory strategy under the revised Clinical Laboratory Improvement Act of 1967 (CLIA '67) and the proposed Clinical Laboratory Improvement Amendments of 1988 (CLIA '88). Use of PT as a regulatory tool corrupts it for things it can do better. PT as a primary regulatory strategy has severe limitations. We explore the nature of these limitations and their implications for clinical laboratories as they impact on the long-term success of HCFA's approved regulatory PT programs in 1991 and beyond, and CLIA '88 PT, which is to be implemented in 1994.
Review of Actual Proficiency-Testing Performance Under CLIA '67 (March 14, 1990) Rules: Perspective from the First Year's Data
Authors: Lanphear B J , Burmeister B J , Ehrmeyer S S , Laessig R H , Hassemer D J 
Published: January 2020

Abstract
Under the Clinical Laboratory Improvement Act of 1967 the Health Care Financing Administration's proficiency-testing requirement applies to approximately 12,000 hospital, reference, and large-clinic laboratories in the United States. The Wisconsin State Laboratory of Hygiene is approved by the Health Care Financing Administration to provide proficiency testing in all specialties and subspecialties. The focus of the program is to provide highly specialized service and support to a limited number of participants in order to assess intralaboratory performance correctly. We report the findings over the four proficiency-testing events in 1991 for the subspecialty of routine chemistry, which serves approximately 470 participants. Failure rates for individual analytes on single proficiency testing events ranged from 0% to 13%. After four events or one year, if the mandated evaluation criteria and failure rules were strictly applied, as many as 11% of the laboratories could have found themselves involuntarily suspended from offering all routine chemistry testing.
Homocysteine Export from Erythrocytes and Its Implication for Plasma Sampling
Authors: Andersson A , Isaksson A , Hultberg B 
Published: January 2020

Abstract
The concentration of free and total homocysteine in plasma increases in time if blood is stored uncentrifuged after sampling. The increase is temperature dependent and the maximal increase in total plasma homocysteine at 37 degrees C was 3.0 mumol.L-1.h-1. Even at 4 degrees C there is a substantial increase, particularly of free plasma homocysteine. Plasma glutathione, cysteinylglycine, and gamma-glutamylcysteine also show an increase in time if whole blood is stored, whereas cysteine decreases. We show that the erythrocytes are responsible for most of the increase in plasma homocysteine and suggest that homocysteine is derived from adenosylmethionine-dependent protein carboxymethylations in the cells. We conclude that strict sampling conditions are necessary when plasma homocysteine and especially its free fraction are assayed.
Detection of α1-Antitrypsin Z and S Mutations by Polymerase Chain Reaction-Mediated Site-Directed Mutagenesis
Authors: Tazelaar J P , Friedman K J , Kline R S , Guthrie M L , Farber R A 
Published: January 2020

Abstract
alpha 1-Antitrypsin (A1AT) deficiency is a relatively common autosomal recessive disease, resulting most often from a single base pair (1 bp) substitution called the Z mutation. Previous genetic tests for carriers and affected patients have relied on quantitative binding of radioactive probes to an amplified gene product, because the mutation does not occur within a restriction enzyme site. Using polymerase chain reaction (PCR)-mediated site-directed mutagenesis, one can introduce a base substitution near the mutation site, such that an inexpensive restriction enzyme (Taq I) can be used to differentiate normal subjects, carriers, and affected patients. We have applied this method to the detection of the Z mutation and the S mutation, which in heterozygotes with a Z allele may lead to the development of symptoms similar to those in ZZ homozygous subjects.
An Overview of Minimally Invasive Technologies
Authors: Ginsberg B H 
Published: January 2020

Abstract
Self-measurement of blood glucose is an integral part of diabetes mellitus therapy. As many as 65% of diabetic people (4-5 million people) perform some degree of self-monitoring and approximately 20-30% do so frequently. Most patients consider this the most onerous part of their diabetes therapy. It requires obtaining blood, frequently in public, and is usually the most painful part of therapy, being significantly more painful than insulin self-administration. Patients therefore are anxious for a less-invasive method for glucose measurement. Methods exist or are being developed for minimally invasive glucose monitoring, which use body fluids other than blood (e.g., sweat and saliva), subcutaneous tissue, or blood measured less invasively. Sweat and saliva are relatively easily obtained but their glucose concentration lags significantly behind blood glucose. Methods to increase sweating have been developed and seem to increase the timeliness of the sweat glucose measurement. Subcutaneous glucose measurement seems to lag only a few minutes behind blood glucose and may actually be a better measurement of the critical values of glucose concentrations in brain, muscle, and other tissue. Glucose can be measured by noninvasive or minimally invasive methods, such as those making skin or mucous membranes permeable to glucose or those placing a reporter molecule in the subcutaneous tissue. Needle-type sensors have been improved in accuracy, size, and stability and can be placed into the subcutaneous tissue or peripheral veins to monitor blood glucose with miniature instruments.
Less-Invasive Measurement of Tissue Availability of Hormones and Drugs: Diffusion-Sink Sampling
Authors: Wade S E 
Published: January 2020

Abstract
The use of small diffusion-sink sampling devices allows the relatively noninvasive and unobtrusive collection of a specimen that represents, in a precisely interpretable way, the average freely diffusing concentration of an analyte over a biologically relevant period of time. In an orally worn configuration, these sampling devices reject artifacts arising from blood plasma contamination of saliva and provide a time-averaged sample without requiring the subject to adhere to a frequent-sampling schedule. The practical advantages of noninvasiveness are thus combined with a fairly direct method for measuring what seems, in light of our current understanding, most important to know about the relative abundance of the steroid hormones. Whether this specificity of measurement also has practical benefits has yet to be tested.
The Anagen System for Automated Fluorometric Immunoassay
Authors: Clements J A , Forrest G C , Jay R F , Jeffery M , Kemp P M , Kjeldsen N J , Rattle S J , Smith A 
Published: January 2020

Abstract
We describe a new discrete microprocessor-controlled analyzer, the AN2000, which fully automates fluorometric immunoassays by using a magnetic separation of the solid phase and an alkaline phosphatase label. It can operate in random-access or batch mode with a dwell time typically less than 20 min. The analysis rate is 75 samples per hour and the system can hold refrigerated reagents for as many as 20 different analytes. The substrate and wash buffer are common to all analytes. The system can hold as many as 80 samples at once. The operator can select from the menu-driven operator interface any combination of the available analytes to be run for each sample, using either the touch screen or the keyboard. Results are calculated from a stored calibration curve that is stable for greater than or equal to 1 month. The AN2000 is capable of automating most assay formats because the available timings, volumes, incubations, and wash cycles can be used in any combination.
Enzymatic Sample Hydrolysis and HPLC in a Study of Phylloquinone Concentration in Human Milk
Authors: Lambert W E , Vanneste L , De Leenheer A P 
Published: January 2020

Abstract
Phylloquinone (vitamin K) is essential to prevent hemorrhagic diseases in newborns. We were interested in determining the concentration of phylloquinone in human milk and in elucidating the factors that influence that concentration. Human milk contains lipid constituents encapsulated with phylloquinone in the fat globules. To eliminate the lipids, we combined sonication and an enzymatic treatment with lipase to prevent degradation by drastic hydrolysis. Despite the low phylloquinone concentrations and the procedure's complexity (lipase treatment, two HPLC steps, and an on-line thermoinduced postcolumn reduction followed by fluorescence detection), within-day and day-to-day CVs of 5.2% and 5.8% were obtained (n = 8, mean = 1.86 micrograms/L, and n = 7, mean = 1.74 micrograms/L, respectively). The mean concentration of phylloquinone in 126 samples was 1.15 +/- 0.82 micrograms/L (mean +/- SD); no correlation was observed between the vitamin concentration and the postpartum date of collection. There was a positive correlation between phylloquinone concentration and phospholipid and cholesterol content (r = 0.5578 and 0.6020, respectively).
Clostebol-Positive Urine after Consumption of Contaminated Meat
Authors: Debruyckere G , de Sagher R , Van Peteghem C 
Published: January 2020

Abstract
We examined the relationship between the consumption of meat from animals treated with anabolic steroids and the detection of these steroids in the athletes consuming this meat. We proved that clostebol metabolites (e.g., 4-chloro-delta-4-androstene-3 alpha-ol-17-one) in the urine of one of the volunteers involved in a feeding experiment were due to accidental consumption of meat contaminated with clostebol acetate. When two volunteers consumed meat (100 g) containing either 1 or 0.1 mg of clostebol acetate, the same metabolite was found in their urine.
Plasma Selenium Concentrations in Patients with Euthyroid Sick Syndrome
Authors: Van Lente F , Daher R 
Published: January 2020

Abstract
We evaluated plasma selenium concentrations in patients with euthyroid sick syndrome express by low serum triiodothyronine (T3) concentrations. Selenium status in these patients was compared with that found in patients with both untreated and treated hypothyroidism. Selenium concentrations in plasma were significantly lower in hospitalized patients with either euthyroid sick syndrome (0.99 +/- 0.37 mumol/L) or treated hypothyroidism (1.09 +/- 0.25 mumol/L) than in patients with untreated hypothyroidism (1.39 +/- 0.28 mumol/L). However, there was no significant, independent relationship between selenium and the thyroid function indices determined in this study. The strongest association was between serum albumin concentration and either selenium (r = 0.65), T3 (r = 0.58), or the molar ratio of T3 to thyroxine (r = 0.64). The decreased average selenium concentration appears to be associated with the hypercatabolic state of severely ill patients, as indicated by the serum albumin concentration; these patients should be considered for selenium supplementation and their selenium status should be monitored.
Rat Plasma Clearance Rate and Organ Distribution of β-Hexosaminidase Isoenzymes from Human Serum
Authors: Isaksson A , Hultberg B , Jonung T 
Published: January 2020

Abstract
beta-Hexosaminidase (EC 3.2.1.30) is markedly increased in human serum in liver disease, chronic alcoholism, and pregnancy. Knowledge of the clearance rate of plasma/serum beta-hexosaminidase is necessary to evaluate this increase. We studied the plasma clearance of beta-hexosaminidase isoenzymes (purified from human serum and placenta) after their infusion into rat circulation. A recently developed enzyme immunoassay method was used to measure the human beta-hexosaminidase isoenzymes; this method relies on both immunoreactivity and enzyme activity, so intact human isoenzymes were measured. In comparison with the placental isoenzymes (t1/2 less than 2 min), the serum forms showed a considerably slower clearance (t1/2 = 2-4 h). However, desialylation of the serum forms resulted in their rapid clearance (t1/2 less than 2 min). The organ localization of the enzyme eliminated from the circulation was investigated 24 h after infusion. Placental and native serum isoenzymes accumulated mainly in the liver and the spleen. Desialylated serum forms were almost exclusively localized to the liver.
Phenol and p-cresol accumulated in uremic serum measured by HPLC with fluorescence detection
Authors: Niwa T 
Published: January 2020

Abstract
We developed a simple and sensitive high-performance liquid chromatographic (HPLC) method that uses fluorescence as a detector for quantifying serum phenol and p-cresol in uremic patients on hemodialysis. Identification of phenol and p-cresol was confirmed by liquid chromatography/mass spectrometry. Because the HPLC method requires only simple extraction by ethyl acetate and does not require further steps such as derivatization, it is simple and rapid compared with gas chromatography or gas chromatography/mass spectrometry. Concentrations of phenol and p-cresol in uremic serum were significantly (p &lt; 0.01) higher than those in normal serum. Reduction rates of phenol and p-cresol by hemodialysis were lower than those of urea and creatinine, suggesting a protein-binding property of phenol and p-cresol. This method will be useful for monitoring serum phenols in dialyzed patients as an index of hemodialysis adequacy.
Interference of carbamylated and acetylated hemoglobins in assays of glycohemoglobin by HPLC, electrophoresis, affinity chromatography, and enzyme immunoassay
Authors: Weykamp C W , Penders T J , Siebelder C W , Muskiet F A , van der Slik W 
Published: January 2020

Abstract
In vitro-synthesized carbamylated and acetylated hemoglobins interfered in assays of glycohemoglobin by HPLC and electrophoresis but had no effects on results obtained by affinity chromatography and enzyme immunoassay. Correlations between long-term serum urea concentrations and glycohemoglobin percentages revealed that, in vivo, carbamylated hemoglobin equivalent to 0.063% of total hemoglobin is formed for every 1 mmol/L of serum urea. The use of acetylsalicylate, either chronically in small doses (200-300 mg/day) or for 1 week at 2000 mg/day, did not cause significant interference from acetylhemoglobin, formed in vivo. We conclude that interference from carbamylated hemoglobin explains only a small part of existing discrepancies between results of glycohemoglobin assays in current use. The interfering effect of acetylhemoglobin formed in vivo with acetyl-CoA as substrate is as yet unknown.
Assay of D-dimer based on immunofiltration and staining with gold colloids
Authors: Gogstad G O , Dale S , Brosstad F , Brandsnes O , Holtlund J , Mørk E , Gärtner E , Borch S M 
Published: January 2020

Abstract
In this immunofiltration assay of D-dimer in plasma samples, the antigens are captured by a monoclonal antibody on a porous membrane, and labeled with the same antibody conjugated to gold colloids. The assay time is &lt; 2 min, and a color of intensity proportional to the concentration of D-dimer is left on the membrane. The reference range (mean +/- 2 SD) was 0.336 +/- 0.133 mg/L (n = 69). Linearity was found up to 10 mg/L. Comparison with ELISA results (x) for 198 patients' samples demonstrated a linear regression equation of y = 0.99(+/- 0.05)x + 0.68(+/- 0.07) and a mean square error of 0.503. Comparison of visual reading of the color signal (y) vs reflectometric measurements (x) for 220 patients' samples demonstrated a linear regression equation of y = 2.5(+/- 0.06)x -0.22(+/- 0.04) and a mean square error of 0.095. Bilirubin, hemoglobin, fibrinogen, soluble fibrin, and fibrinogen degradation products and freezing/thawing of samples did not interfere. Some interference from rheumatoid factor, heparin, and the presence of cells or large lipid particles was seen. The variance (CV) was 8-12% within run, 10-18% between runs, and 13-20% between persons. The new assay constitutes a rapid and reliable analytical tool combining simplicity equivalent to that of latex tests with analytical information approaching that of ELISA.
Determination of apolipoprotein E genotypes by single-strand conformational polymorphism
Authors: Tsai M Y , Suess P , Schwichtenberg K , Eckfeldt J H , Yuan J , Tuchman M , Hunninghake D 
Published: January 2020

Abstract
We used single-strand conformational polymorphism (SSCP) to determine apolipoprotein E (Apo E) genotypes in 47 individuals. A 295-base-pair (bp) DNA fragment coding for amino acid residues 80-178 of the Apo E protein gave distinct patterns for the three alleles. When we used SSCP to determine the Apo E polymorphism of five individuals whose phenotyping results differed from those of genotyping, the SSCP results agreed with the genotyping results obtained by the PCR-based amplification refractory mutation system (ARMS). Because most of the reported rare alleles of the Apo E gene involve mutations of amino acid residues in positions 120-160, our SSCP method is useful for determining rare as well as common alleles.
Kinetic determination of serum adenosine deaminase
Authors: Oosthuizen H M , Ungerer J P , Bissbort S H 
Published: January 2020

Abstract
A new kinetic method for the determination of serum adenosine deaminase (EC 3.5.4.4) is described, with adenosine as the substrate and nucleoside phosphorylase and xanthine oxidase as the reaction enzymes. Inosine is produced, which is converted to hypoxanthine. The hypoxanthine is oxidized to xanthine, which is further oxidized to uric acid. In these two reactions, blue 2,6-dichlorophenolindophenol is reduced to a colorless compound and the decrease in color is measured spectrophotometrically at 606 nm. The assay was automated by using a Cobas Mira analyzer. The automated assay had a CV of &lt; 7%, and the calibration curve was linear from 10 to 120 U/L. The assay correlates well with an established method, based on detection of liberated NH3 with Berthelot's reaction. The reference interval (mean +/- 2 SD) was 14-34 U/L (mean 24 U/L, n = 84). The enzymatic method described is easily automated and seems to be suitable for the routine determination of adenosine deaminase in serum.
Method for determining reference changes from patients' serial data: example of cardiac enzymes
Authors: Kairisto V , Virtanen A , Uusipaikka E , Voipio-Pulkki L M , Näntö V , Peltola O , Irjala K 
Published: January 2020

Abstract
Changes between serial laboratory test results can be significant, even if none of the individual results exceeds the reference interval. We developed a statistical method for the calculation of reference change limits from routine patients' data for situations in which the majority of the patients can be considered suitable reference subjects. The method was applied to cardiac enzyme data [creatine kinase (CK; EC 2.7.3.2), creatine kinase isoenzyme MB (CK-2), lactate dehydrogenase (LD; EC 1.1.1.28), and lactate dehydrogenase isoenzyme 1 (LD-1)] from 2029 consecutive patients. We used hospital discharge diagnoses to exclude patients with the diagnosis of myocardial infarction or myocarditis, but we also studied the characteristics of the method on unselected patients' data. The reference change limits derived from the diagnosis-selected patient group were as follows (U/L, activity measurements in serum at 37 degrees C according to Scandinavian recommendations): CK from -39 to 27, CK-2 from -8 to 7, LD from -86 to 85, and LD-1 from -19 to 15. Similar limits were obtained by conventional statistical methods from a group of 29 hospitalized patients with no myocardial symptoms. Our results suggest that it is possible to produce clinically applicable reference change limits from routine data.
Models of neoplasia and their diagnostic implications: a historical perspective
Authors: Goldberg D M , Diamandis E P 
Published: January 2020

Abstract
In comparison with normal cells, cancer cells have an enhanced ability to trap both nitrogen and energy; an enhanced operation of the glycolytic and direct oxidative pathways, leading to accumulation of lactate and increased production of NADPH; and a greater content of lysosomal hydrolases. These changes represent a reprogramming of gene expression, which, at its most specific, is accompanied by the reappearance in the cell and ultimately in the body fluids of oncodevelopmental proteins not normally found in mature adult tissues. The most florid stage of this reprogramming leads to the metastatic phenotype, which confers upon the cancer cell the ability to stimulate angiogenesis, invade the bloodstream and lymphatic vessel, and arrest and proliferate in distant tissues. The diagnostic implications of these phenotypic changes are illustrated for cancer of the cervix uteri and cancer of the colon. We also review the classical theories of neoplasia, including the cellular anoxia concept of Warburg, the deletion hypothesis of Potter, and various other mechanisms emphasizing genomic derepression and impaired immunity. The critical steps in chemical carcinogenesis are described, and the Vogelstein-Lane model is presented, emphasizing the stepwise and cumulative genomic changes affecting chromosomes 5q, 17p, 18q, and gene amplification of chromosome 12 as well as genomic instability resulting from reduced DNA methylation. The main consequences of these genomic alterations include overexpression or activation of oncogenes such as c-myc and k-ras, together with mutation or functional inactivation of suppressor genes such as p53. Finally, the implications of these findings for diagnosis and management are illustrated by reference to recent investigations in cancers of the breast, colon, and bladder, in which these genomic alterations can be detected by examination of appropriate cellular material and by detection in serum of antibodies to the p53 gene product.
Quantitative analyses of the interaction between calcium ions and human serum albumin
Authors: Kragh-Hansen U , Vorum H 
Published: January 2020

Abstract
We examined the suitability of nine organic buffers for studying calcium binding to albumin by equilibrium dialysis. Results obtained with defatted human serum albumin showed that 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 2-([tris(hydroxymethyl)methyl] amino)ethanesulfonic acid were superior. Scatchard analysis of the experimental data from an extensive study performed in HEPES at pH 7.4 and 20 degrees C revealed (putting n(i) = 1, i = 1-4) k1 = 367 L/mol, k2 = 314 L/mol, k3 = 291 L/mol, and k4 = 179 L/mol. The very weak binding was characterized as n5 = 10 and k5 = 40 L/mol. The results were also analyzed in terms of stoichiometric association constants. The constants K1 and K2 were calculated to be 1513 and 647 L/mol, respectively, whereas the other constants were considered undeterminable. pH studies showed that in the interval 6.8-7.4, binding was not influenced by changes in acidity. Increasing pH to above the physiological value resulted in increased binding. At pH 8.0, k1 was increased almost fourfold, whereas k2 and k3 were approximately doubled. These findings indicate that the neutral to basic transition is important for the calcium-binding properties of albumin. The transition is a reversible, gradual conformational change of the protein at pH 6-9.