bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary evaluation of an experimental clinical chemistry analyzer developed for space medicine
Authors: Wu A H , Gornet T G , Schenkel O , Smith-Cronin L , Graham G A , Tonnesen A S , McKinley B A 
Published: January 2020

Abstract
An experimental clinical chemistry analyzer system was designed and built to demonstrate the feasibility of clinical chemistry as part of a medical-care system at NASA's planned space station Freedom. We report the performance of the experimental analyzer, called a medical development unit (MDU), for selected analytes in a laboratory setting in preparation for a preliminary clinical trial at patients' bedsides in an intensive-care unit. Within-run CVs ranged from 0.7% for sodium to 7.1% for phosphorus; day-to-day CVs ranged from 1.0% for chloride to 23.4% for calcium. Correlation of patients' blood sample analyses compared well with those by Ektachem E700 and other high-volume central laboratory analyzers (r ranged from 0.933 for creatine kinase MB isoenzyme to 0.997 for potassium), except for hemoglobin (r = 0.901) and calcium (r = 0.823). Although several CVs obtained in this study exceeded theoretical desired precision limits based on biological variations, performance was adequate for clinical laboratory diagnosis. We examined the effect of potentially interfering concentrations of hemoglobin, bilirubin, and lipids: the only effect was negative interference with calcium analyses by high concentrations of bilirubin. We also examined the effects of preanalytical variables and the performance of experimental sample-transfer cups designed to retain sample and reference liquid in microgravity. Continued development of the MDU system is recommended, especially automation of sample processing.
Reliability and feasibility of pregnancy home-use tests: laboratory validation and diagnostic evaluation by 638 volunteers
Authors: Daviaud J , Fournet D , Ballongue C , Guillem G P , Leblanc A , Casellas C , Pau B 
Published: January 2020

Abstract
All 27 home-use tests sold in France in 1989 for the self-diagnosis of pregnancy were evaluated. The kits were first tested by qualified clinical chemistry technologists. Eleven kits with 100% specificity and 100% sensitivity were retained for the diagnostic study. Each of 638 laywomen was given a kit and asked to perform the assay with a coded urine specimen containing either no human chorionic gonadotropin (hCG) or an hCG concentration adjusted to the claimed detection limit (1 DL) or twice the detection limit (2 DL). After testing, each participant filled out a detailed questionnaire. The results showed a diagnostic specificity of 86-100% for 10 kits but a diagnostic sensitivity of 85-100% for only 5 kits at 2 DL and for only 2 at 1 DL. Among the 478 positive urine samples distributed, 230 were falsely interpreted as negative. The main explanation for such a high percentage of false-negative results was difficulty in understanding the explanatory leaflets accompanying the kits and hence in reading the results, regardless of the socioeconomic situation of the participant. We conclude that pregnancy home-use tests should be subjected to rigorous analytical controls and evaluated by a panel of potential users before being released on the market.
Differences in serum potassium concentrations in normal men in different geographic locations
Authors: Reidenberg M M , Gu Z P , Lorenzo B , Coutinho E , Athayde C , Frick J , Alvarez F , Brache V , Emuveyan E E 
Published: January 2020

Abstract
Hypokalemia has been associated with the taking of gossypol, a potential oral antifertility drug for men. Because the frequency of this response differed in different parts of the world, this study was done to learn if "normal" serum [K+] also differed. [K+] was measured by flame photometry in serum from apparently normal men from Austria (n = 30), China (53), Brazil (100), the Dominican Republic (38), and the US (103), and in plasma from Nigerian men (82). The mean (SD) for [K+] in Chinese men, 3.82 (0.27) mmol/L, was lower than that in Brazilians [4.06 (0.29) mmol/L], Austrians [4.14 (0.44) mmol/L], Dominicans [4.37 (0.33) mmol/L], or Americans [4.38 (0.37) mmol/L]. Apparently there are regional differences in average serum [K+], with men in China having lower serum [K+] than men elsewhere. This may predispose them to hypokalemia.
HPLC of folinic acid diastereoisomers and 5-methyltetrahydrofolate in plasma
Authors: Etienne M C , Speziale N , Milano G 
Published: January 2020

Abstract
We present a rapid, sensitive, and automated HPLC method with direct resolution of l-folinic acid (l-FA), d-folinic acid (d-FA), and 5-methyltetrahydrofolate (5MTHF) from plasma samples. Plasma (500 microL) is first extracted on solid phase (RP-18 cartridge). The dI-FA peak is collected on-line from a reversed-phase column (RP-8, 119 x 2 mm, 4 microns: HPLC 1) and then automatically loaded onto a chiral stationary phase (human serum albumin, 150 x 4.6 mm, 7 microns: HPLC 2). The same mobile phase flows in both systems (0.2 mol/L Na2HPO4:1-propanol, 98:2, pH 6.2). HPLC 1 allows quantification of 5MTHF by absorption at 313 nm; HPLC 2, the quantification of l-FA and d-FA by electrochemical detection in the oxidation mode (total run time 18 min). Recoveries are &gt; 80%. CVs for intra- and interassay reproducibilities are &lt; 5% and 15%, respectively. Linearity of the response (0.1-1 mumol/L and 1-50 mumol/L, r = 0.99, P &lt; 0.01) is satisfactory. The sensitivity limit is 50 nmol/L for 5MTHF and 20 nmol/L for l-FA and d-FA. This assay is substantially improved over existing methods regarding feasibility and is being used in pharmacokinetic investigations in cancer patients.
Detection and characterization of blocking-type anti-acetylcholine receptor antibodies in sera from patients with myasthenia gravis
Authors: Hara H , Hayashi K , Ohta K , Itoh N , Nishitani H , Ohta M 
Published: January 2020

Abstract
We developed a highly sensitive, convenient assay for measuring blocking-type anti-acetylcholine receptor antibodies, which inhibit the binding of 125I-labeled alpha-bungarotoxin (alpha-BuTx) to the acetylcholine receptor (AChR). This procedure detected inhibitory activities in sera from 76% of patients with myasthenia gravis. Results of an experiment done with synthetic peptide corresponding to the alpha-BuTx binding region in the alpha-subunit of Torpedo AChR suggested that this inhibition is due to nonspecific steric hindrance caused by the binding of antibodies to a region other than the alpha-BuTx site, rather than by direct binding to the latter site. The inhibitory activities of the blocking-type antibodies and the titers of non-blocking-type antibodies were correlated. Moreover, the blocking-type antibodies could dissociate 125I-labeled alpha-BuTx from 125I-labeled alpha-BuTx-human AChR complex, and their dissociation activities showed good correlation with the inhibitory activities.
Abbott AxSYM random and continuous access immunoassay system for improved workflow in the clinical laboratory
Authors: Smith J , Osikowicz G 
Published: January 2020

Abstract
We describe a new clinical laboratory instrument, the Abbott AxSYM, which provides random- and continuous-access testing for immunoassays, 20 onboard reagents, primary tube sampling, and a throughput of 80 to 120 tests per hour. The AxSYM incorporates three separate analytical technologies for processing immunoassays: microparticle enzyme immunoassay, fluorescence polarization immunoassay, and a novel technology known as ion-capture immunoassay. The system incorporates both common and technology-specific subsystems controlled by a real-time software scheduling processor. Tests can be processed in one- or two-step sandwich or competitive formats, with variable pipetting steps, incubation periods, optical read formats, and wash sequences. Menu capabilities include tests for hepatitis, retrovirus, tumor markers, fertility markers, thyroid functions, and therapeutic drugs. The time to first result is approximately 15-25 min for most routine assays and &lt; or = 15 min for stat assays (i.e., creatine kinase MB isoenzyme, human chorionic gonadotropin beta subunit, and therapeutic drugs). AxSYM assay performance for 23 assays was comparable with that of the Abbott IMx and TDx analyzers; specimen correlation data had correlation coefficients ranging from 0.97 to 0.99 and slopes ranging from 0.99 to 1.10. Within-run imprecision (CV) was 1.5% to 11.4%, with most assays (19 of 23) demonstrating CVs &lt; or = 8.0%.
Simultaneous assay of alpha-fetoprotein and free beta subunit of human chorionic gonadotropin by dual-label time-resolved immunofluorometric assay
Authors: Pettersson K , Alfthan H , Stenman U H , Turpeinen U , Suonpää M , Söderholm J , Larsen S O , Nørgaard-Pedersen B 
Published: January 2020

Abstract
We developed a simple, rapid two-step dual-label assay for the noncompetitive determination of alpha-fetoprotein (AFP) and beta subunit of human chorionic gonadotropin (hCG beta) in serum. Monoclonal antibodies to detect AFP and hCG beta were labeled with europium (Eu) and samarium (Sm), respectively. Highly fluorescent chelates were developed by using the Delfia enhancement principle. The detection limits for AFP and hCG beta were approximately 0.02 kIU/L and approximately 0.2 IU/L, respectively. The within-run precision was &lt; 5% over the whole range of AFP (1-500 kIU/L) and hCG beta (1-200 IU/L) concentrations tested. Cross-reaction of intact hCG was &lt; 0.03%. The AFP concentrations determined with the dual-label assay correlated well with those obtained by Delfia AFP single-label kit. The concentrations of hCG beta were in good agreement with recently published data. Storing the serum samples for 24 h or 1 week at room temperature increased the hCG beta concentration by 4% and 26%, respectively. At 35 degrees C this dissociation of hCG increased 30-40-fold. Repeated freezing and thawing had no effect on the hCG beta concentration.
Highly sensitive enzyme immunoassay of proinsulin immunoreactivity with use of two monoclonal antibodies
Authors: Kjems L L , Røder M E , Dinesen B , Hartling S G , Jørgensen P N , Binder C 
Published: January 2020

Abstract
A highly sensitive two-site sandwich ELISA measuring total proinsulin immunoreactive material in serum or plasma was developed. The assay was based on two monoclonal antibodies, an anti-C-peptide antibody bound to a microtest plate and a biotin-labeled anti-insulin antibody. The detection limit (3 SD above zero value) in buffer was 0.05 pmol/L, corresponding to 0.25 pmol/L in human serum (diluted 1:5). The linear calibrator range was 0.05-20 pmol/L. Interassay CVs were 4.7% at a median (range) of 2.3 pmol/L (1.4-2.8 pmol/L, n = 8), 6.7% at 5.1 pmol/L (3.3-8.0 pmol/L, n = 8), and 8.7% at 10.0 pmol/L (8-12 pmol/L, n = 10). Mean analytical recovery of added human proinsulin (hPI) (2, 5, and 10 pmol/L) to serum was 84% (range 68-128%, n = 9). Human insulin and human C-peptide did not cross-react at 5000 and 10,000 pmol/L, respectively. The four major proinsulin conversion intermediates reacted 65-99%: split(32-33)hPI 74%, des-(31,32)hPI 65%, split(65-66)hPI 78%, and des(64,65)hPI 99%. All serum values from 38 fasting healthy subjects were above the detection limit: median (range) 4.0 (2.1-12.6) pmol/L.
Competitive time-resolved immunofluorometric assay for quantifying carbonic anhydrase VI in saliva
Authors: Parkkila S , Parkkila A K , Vierjoki T , Ståhlberg T , Rajaniemi H 
Published: January 2020

Abstract
A competitive time-resolved immunofluorometric assay sensitive and robust enough for quantifying human salivary carbonic anhydrase isoenzyme VI (HCA VI) was developed. The solid-phase immunoassay is based on competition between Eu(3+)-labeled HCA VI and salivary HCA VI for polyclonal rabbit anti-HCA VI antibodies that are attached to microtiter plate wells precoated with sheep anti-rabbit IgG. The subsequent immunoassay including the separation of free and bound HCA VI requires only one incubation step, after which the Eu3+ of the bound labeled antigen is released into an enhancement solution. The highly fluorescent Eu chelates formed in this solution are then quantified by time-resolved fluorometry (Delfia). The time-resolution principle effectively obviates possible interferences from complex biological material such as saliva. The assay detection limit was 1.5 micrograms/L. Intra- and interassay imprecisions (CVs) were 5.1% and 5.3%, respectively. The mean analytical recovery was 93%. The mean +/- SD concentration of HCA VI in paraffin-stimulated saliva was 6.8 +/- 4.3 mg/L (n = 30) and the secretion rate was 10.2 +/- 7.9 micrograms/min. The method was useful for further investigations of the role of HCA VI in difficult matrices, e.g., saliva.
"Hot spots" mutation analysis of p53 gene in gastrointestinal cancers by amplification of naturally occurring and artificially created restriction sites
Authors: Chen P H , Lin S Y , Wang C K , Chen Y J , Chen T C , Chang J G 
Published: January 2020

Abstract
We developed a rapid, simple method to detect "hot spot" point mutations of the p53 gene. A DNA fragment from cancer tissue of a surgical specimen was selectively amplified with specific oligonucleotide primers and then digested with restriction enzymes that recognized artificial or naturally occurring restriction sites. To detect mutations in codons 273 and 245, we created artificial Bst U1 and BgI I sites by introducing a single nucleotide mismatch into the respective mutagenesis primers. We used the naturally occurring restriction sites of Msp I, Hae III, and Hha I to detect mutations in codons 248, 249, and 175, respectively. In 74 cases of gastrointestinal cancer, 5 of 35 colorectal cancers showed mutations; 1 of 15 cases of gastric cancers showed mutation; and 1 of 24 hepatocellular carcinomas showed mutation. This nonradioactive method is an accurate and clinically useful way to detect hot-spot point mutations of the p53 gene in gastrointestinal cancers.
Prediction of alcohol-related harm by laboratory test results
Authors: Conigrave K M , Saunders J B , Reznik R B , Whitfield J B 
Published: January 2020

Abstract
We examined the value of laboratory markers of excessive alcohol (ethanol) intake as predictors of mortality, morbidity, and health-care utilization in a cohort of 330 patients attending an acute ambulatory care service. Among men, all four markers examined--gamma-glutamyltransferase (GGT) and aspartate aminotransferase (AST) activities, high-density lipoprotein cholesterol (HDL-C), and mean corpuscular volume (MCV)--were predictive of medical sequelae and health-care utilization over a 3-year period. In contrast, social problems were more closely related to the amount of alcohol consumption at initial assessment than to any biological marker. Serum GGT and AST activities and MCV were predictive of medical sequelae in women. The predictive value of GGT was an independent risk factor and did not merely reflect recent alcohol intake or the presence of chronic liver disease. We conclude that these readily available laboratory tests provide important prognostic information and should be an integral part of the assessment of persons with hazardous alcohol consumption.
HemoCue beta-glucose photometer evaluated for use in a neonatal intensive care unit
Authors: Vadasdi E , Jacobs E 
Published: January 2020

Abstract
We evaluated the HemoCue beta-Glucose Photometer system for use in our neonatal intensive care unit by assaying 178 heparinized whole-blood samples obtained by heel stick. The required sample size is 5 microL. Plasma glucose was analysed by a glucose oxidase/oxygen electrode methodology. Across the glucose range of 1.28-21.87 mmol/L, the regression slope was 0.976 (r = 0.976, Sy/x = 0.475). For samples with hematocrit &lt; or = 0.30, the regression slope was 0.981 (r = 0.950, Sy/x = 0.415); for hematocrit of 0.31-0.49, the regression slope was 0.984 (r = 0.972, Sy/x = 0.508); and for hematocrit &gt; or = 0.50, the regression slope was 0.959 (r = 0.988, Sy/x = 0.394). Human whole blood, bovine whole blood, and bovine serum-based quality-control materials were studied. Except for assays of the low-concentration human control material, the total CV was &lt; 3.5%. The accuracy and precision of the HemoCue system were comparable with those of conventional laboratory instrumentation.
Platelet serotonin content and free and total plasma tryptophan in healthy volunteers during 24 hours
Authors: Eynard N , Flachaire E , Lestra C , Broyer M , Zaidan R , Claustrat B , Quincy C 
Published: January 2020

Abstract
The determination of platelet serotonin (5-HT) and plasma tryptophan concentrations is useful in the diagnosis, investigation of etiologies, and treatment of psychiatric disorders. To determine the usual circadian variations in platelet 5-HT and free and total tryptophan concentrations, we measured these variables during 24 h at 1-h intervals and every 30 min from 2000 to 0800 in seven clinically healthy young men with an HPLC method. No common circadian rhythm for platelet serotonin concentrations was observed in our subjects; however, there was a distinct rhythm for both free and total plasma tryptophan: Concentrations were maximal in the afternoon and minimal during the night.
Clinical applications of serum and tissue markers in malignant disease: breast cancer as the paradigm
Authors: Schwartz G F , Schwarting R , Rabindranauth P , Finkel G C 
Published: January 2020

Abstract
Within the past few years, the measurement of serum and tissue markers, especially the latter, has assumed a more significant role influencing clinical decisions about treatment and follow-up of patients with malignant disease. Breast cancer is a useful paradigm to illustrate the types and importance of these various markers. Tissue markers, including nuclear grade, steroid hormone receptors, DNA index, ploidy, expression of oncogenes or tumor-suppressor genes, epidermal growth factors, cathepsin D, proliferating cell nuclear antigen (PCNA), Ki-67, p32, and others, may influence choices of initial treatment as well as adjuvant chemotherapy and (or) hormone administration. The serial measurement of serum markers, those currently available and those on the horizon, for example, may offer a way to monitor patients at risk for recurrent cancer. Although the current role of these markers may be controversial, as information about them is collected and refined, in the future perhaps a panel of such studies could be incorporated into forthcoming clinical staging systems for carcinoma of the breast and other malignancies to define both treatment and outcome.
Rapid, direct enzyme immunoassay of 11-keto-thromboxane B2 in urine, validated by immunoaffinity/gas chromatography-mass spectrometry
Authors: Djurup R , Chiabrando C , Jörres A , Fanelli R , Foegh M , Soerensen H U , Joergensen P N 
Published: January 2020

Abstract
We have developed a direct enzyme immunoassay (EIA) for quantifying immunoreactive 11-keto-thromboxane B2 (iKTXB) in unprocessed human urine. Cross-reactivity with other thromboxane metabolites and prostanoids was negligible. Analytical recovery of 11-keto-TXB2 in urine specimens was 97.4% to 99.8%. Total imprecision for two clinical specimens was 8.5% and 12.2%. Intake of acetylsalicylic acid decreased the measured concentration of iKTXB. Cardiopulmonary bypass, a procedure known to activate platelets, increased the mean excretion rate of iKTXB 10-fold. Simultaneous gas chromatography-mass spectrometry analysis of 11-keto-TXB2 and 11-keto-2,3-dinor TXB2 in urine specimens (n = 17) from healthy subjects indicated that urinary iKTXB concentrations measured by EIA represented a sum of the two 11-keto metabolites. We conclude that the direct EIA is sufficiently sensitive, rapid, simple, and specific to allow screening for alterations in thromboxane biosynthesis in patients.
Improved rapid procedure for simultaneous determinations of hemoglobins A1a, A1b, A1c, F, C, and S, with indication for acetylation or carbamylation by cation-exchange liquid chromatography
Authors: Brunnekreeft J W , Eidhof H H 
Published: January 2020

Abstract
Although the clinical utility of glycohemoglobin (HbA1c) as an indicator of blood glucose control is generally accepted, the use of cation-exchange liquid chromatography for its quantification is controversial, given numerous studies that show no correlation between HbA1c and other indicators of blood glucose control in uremic subjects. We report a specific cation-exchange liquid-chromatographic method that measures simultaneously HbA1a, HbA1b, HbA1c, HbF, HbA0, HbC, and HbS quickly and reproducibly. Carbamylation or acetylation is indicated by extra peaks. Carbamylated hemoglobin increased the result for HbA1c by as much as 1% above the nonuremic value. The method is a fast (approximately 15 min per sample), easy to perform, reproducible, and sensitive screening method for abnormal hemoglobins. Within-assay CVs were &lt; 0.7% in all cases and between-assay CVs were &lt; 1.4%.
Optimized steps in fluorometric determination of thiobarbituric acid-reactive substances in serum: importance of extraction pH and influence of sample preservation and storage
Authors: Wasowicz W , Nève J , Peretz A 
Published: January 2020

Abstract
A simple, reliable, and reproducible fluorometric method for measuring thiobarbituric acid-reactive substances (TBARS) in serum is proposed, based on the reaction between malondialdehyde (MDA) and thiobarbituric acid. Formation of TBARS was complete at pH 2.4-2.6, but extraction with n-butanol proved complete only at lower pH, i.e., 1.6-1.7. Analytical recoveries of MDA added to serum were 94%-101%; within- and between-run CVs were 2.4-3.6% and 4.6-5.5%; and the detection limit for TBARS in serum was 0.10 mumol/L. Optimized conditions included: (a) collection of either serum or heparinized plasma, (b) preservation from in vitro autoxidation by glutathione and EDTA, and (c) storage at -20 degrees C up to 35 days. The mean (+/- SD) TBARS concentration in 47 healthy adults was 1.01 (0.21) mumol/L; no sex-related difference was observed. Higher concentrations were measured in patients with renal insufficiency undergoing hemodialysis and in patients with insulin-dependent diabetes, chronic pancreatitis, or liver cirrhosis.
Does tumor-derived human chorionic gonadotropin act as a thyroid stimulator in vivo?
Authors: Madersbacher S , Schwarz S , Mann K , Klieber R , Wick G , Berger P 
Published: January 2020

Abstract
To evaluate in vivo the proposed intrinsic thyroid-stimulating hormone (TSH) activity (TSA) of human chorionic gonadotropin (hCG), we monitored over 0.5-1 years the thyroid status of eight patients with hCG-producing non-seminomatous testicular cancer. The patients' sera were analyzed for concentrations of hCG, free thyroxine (fT4), hTSH, and thyroxine-binding globulin (TBG). All patients had excessively high concentrations of hCG (1 x 10(5)-5 x 10(8) ng/L, mean: 1 x 10(7) ng/L) before polychemotherapy, which decreased under successful therapy to physiological values (&lt; 240 ng/L). Although the serum concentrations of hCG varied by more than six orders of magnitude, we saw no changes and no correlation (P &gt; 0.05) between the concentrations of hCG and the concentrations of fT4 and hTSH. Not even when hCG concentrations were greatest (&gt; 5 x 10(7) ng/L) were any signs of hyperthyroidism observed: fT4 (3.5-13 ng/L) and hTSH (9-700 ng/L) were in the physiological range in all patients and remained so during chemotherapy. The results of this longitudinal study were confirmed in analyzing the data for all eight patients (total: 82 samples) cross-sectionally. Again, we found no correlation (P &gt; 0.05) between the concentrations of hCG and fT4 or hCG and hTSH. We conclude that even excessive amounts of testicular tumor-derived hCG do not display any TSH-like activity in vivo.