bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bioassay of parathyrin: analytical characteristics and clinical performance in patients with hypercalcemia.
Authors: Klee G G , Preissner C M , Schloegel I W , Kao P C 
Published: January 2020

Abstract
This new bioassay for parathyrin (PTH) in plasma (bio-PTH) combines immunoextraction on affinity columns [goat anti-hPTH (1-44) conjugated to Sepharose 4B] and a receptor assay involving an osteosarcoma cell line. The mean extraction efficacy ranges from 87% (as determined with immunopurified 125I-labeled PTH) to 62% for hPTH bioactivity. The assay is standardized with synthetic hPTH (1-84) and can detect as little as 0.9 pmol/L of PTH in 2 mL of plasma. In 100 healthy adults, the 95% reference interval for bio-PTH was less than 0.9 to 6.1 pmol/L (median, 2.0 pmol/L). In 185 patients with surgically confirmed hyperparathyroidism, bio-PTH concentrations ranged from 1.0 to greater than 120 pmol/L (median, 12.9 pmol/L); 80% of values were greater than 6.1 pmol/L. In 50 patients with both preoperative and postoperative determinations, the mean (+/--SD) concentrations of calcium in serum were 113 +/- 10 and 89 +/- 6 mg/L, respectively; the median bio-PTH concentrations were 13.6 and 2.0 pmol/L, respectively. In 22 patients with nonparathyroid-mediated hypercalcemia, the concentration of bio-PTH ranged from less than 0.9 to 5.3 pmol/L (median, 1.8 pmol/L). This bio-PTH assay is slightly less sensitive than our GP235 immunoreactive PTH (iPTH) immunoassay for detecting hyperparathyroidism (Clin Chem 1982;28:69-74); however, the bioassay is more specific and detected some cases missed by the iPTH assay. Overall, 95% of the hyperparathyroid patients had an increased test result for either the bio-PTH or the iPTH assay.
New approach to competitive lanthanide immunoassay: time-resolved fluoroimmunoassay of progesterone with labeled analyte.
Authors: Déchaud H , Bador R , Claustrat F , Desuzinges C , Mallein R 
Published: January 2020

Abstract
This solid-phase competitive europium immunoassay of progesterone in plasma relies on antigen labeling. With this new approach, time-resolved fluoroimmunoassay can attain sensitivity and precision similar to that of conventional radioimmunoassay. The europium-labeling involves coupling diethylenetriaminepentaacetic acid (chelating agent for Eu3+) to a progesterone-protein conjugate. The solid-phase antibody is immobilized inside polystyrene tubes in which plasma samples (50 microL) are assayed directly, without preliminary extraction. After incubation in the presence of trichloroacetic acid, the tubes are washed and the fluorescence intensity of europium is measured by time-wavelength-resolved fluorometry, with a nitrogen laser as the pulsed excitation source. Progesterone values obtained by this procedure agreed well with those obtained by radioimmunoassay (r = 0.98, n = 97). The detection limit was equivalent to that of most RIAs (0.2 micrograms/L).
Changes in serum enzymes in moderate drinkers after an alcohol challenge.
Authors: Nemesánszky E , Lott J A , Arato M 
Published: January 2020

Abstract
When 14 "moderate" drinkers abstained from alcohol for four weeks, the activity of gamma-glutamyltransferase (GGT; EC 2.3.2.2) in their serum showed a large decrease. Immediately after the period of abstention, an orally given ethanol challenge of 1 g/kg produced a marked increase in serum GGT at 24 h, followed by a slow decline thereafter. Aspartate amino-transferase activity in serum was significantly increased at 24 h; however, alkaline phosphate, alanine aminotransferase, and lactate dehydrogenase showed much smaller or no changes. An abnormal increase in lactate dehydrogenase isoenzyme 5 was observed in seven subjects. In some of the moderate drinkers, liver biopsies showed mild chronic hepatitis or nonspecific changes. Eight nondrinking controls showed only slight increases in serum GGT following the same alcohol challenge; results for the other enzyme tests were unchanged. We consider it probable that pre-existing liver disease affects the response to ethanol, so that greater amounts of GGT are released from hepatic tissue; alternatively, drinkers may have a higher GGT activity in this tissue as a result of enzyme induction by ethanol. The alcohol challenge test was an effective discriminator between moderate drinkers and abstainers.
Effect of creatine kinase-MM subtype composition on a CK-MB immunoinhibition assay.
Authors: Morison I M , Clayson K J , Fine J S 
Published: January 2020

Abstract
Immunoinhibition (INH) by use of polyclonal anti-human CK-M antibody may be used to measure CK-MB in serum. Previous studies have shown that inhibiting antibodies prepared against purified muscle extracts may inhibit CK-MM by greater than 99%. Using patients' sera and muscle homogenates incubated with human serum, we studied the effect of CK-MM subtype composition on an INH assay. We found that with increasing time from the CK-releasing event, e.g., myocardial infarction, or with longer in vitro incubation, the proportion of CK-MM1 increased and the proportion of uninhibited CK-MM increased from 0.2% to 0.7-0.8%. As a consequence, CK-MB activity may be overestimated by as much as 1.6% of total CK when uncorrected INH results are used. Inhibition was maximal in samples containing 100% CK-MM3, the tissue subtype. Because of the time-dependent change in CK-MM subtypes, published results for INH from studies in which CK-MM purified from muscle was used may not be directly applicable to clinical specimens.
Anodic stripping voltammetry procedure modified for improved accuracy of blood lead analysis.
Authors: Roda S M , Greenland R D , Bornschein R L , Hammond P B 
Published: January 2020

Abstract
In evaluating the accuracy and reliability of blood lead (PbB) measurements with the Environmental Science Associates Model 3010A Trace Metal Analyzer, intralaboratory comparison demonstrated that use of the operating conditions recommended by the manufacturer resulted in consistently underestimated PbB concentrations less than 400 micrograms/L and overestimated PbB values greater than 400 micrograms/L. At PbB concentrations less than 50 micrograms/L, measured concentrations were often registered as negative results. However, these negative values could be replicated to within +/- 10 micrograms/L, indicating good precision of the method, but obviously not good accuracy. In addition, lower-than-expected lead (Pb) values were measured in samples containing increased concentrations of copper (Cu), such as may occur in pregnant women. We modified the procedure to eliminate these inaccuracies by substituting manual peak-height measurements for reliance on the integrator and digital display of the instrument. We established the accuracy of the modified procedure by using calibration standards previously quantified by isotope dilution-mass spectroscopy. A quality-control program for monitoring PbB analysis is also described.
Ten highly sensitive thyrotropin assays compared by receiver-operating characteristic curves analysis: results of a prospective multicenter study.
Authors: Thonnart B , Messian O , Linhart N C , Bok B 
Published: January 2020

Abstract
We report a prospective multicenter study, undertaken to compare the efficacy of 10 highly sensitive thyrotropin assay kits for the diagnosis of hyperthyroidism. Performances of the kits were compared with a reference diagnosis based on clinical examination, pertinent biological tests, and determination by an independent laboratory of the concentrations in serum of free triiodothyronine and free thyroxin. No thyrotropin determination was used in establishing this reference diagnosis. Receiver-operating characteristic curves were obtained for results from 600 patients (217 hyperthyroid and 383 euthyroid) by each kit. Even though analyses were performed out of the working range of most kits, the clinical correlation was nevertheless excellent. The best results corresponded to a sensitivity of 97.5% associated with a specificity of 96.1% and were significantly better than those obtained with all other kits. Results of this comparison depended greatly on the heterogeneity of the "normal"/"abnormal" categories. When only diffuse hyperthyroidism was considered, sensitivity and specificity were improved for all kits, and there was no significant difference among the five best kits.
Improved thin-layer chromatographic determination of phospholipids in gastric aspirate from newborns, for assessment of lung maturity.
Authors: Serrano de la Cruz D , Santillana E , Mingo A , Fuenmayor G , Pantoja A , Fernández E 
Published: January 2020

Abstract
This one-dimensional thin-layer chromatographic method is used for assay of phospholipids in the gastric aspirate of newborns. The solvent mixture (chloroform/hexane/methanol/glacial acetic acid/water, 12/7/4/3/0.3 by vol) completely resolves lecithin, sphingomyelin, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol. The method is simple, precise, inexpensive, and rapid (chromatographic development takes less than 25 min) and gives high chromatographic resolution. We used this method to determine the lecithin/sphingomyelin densitometric ratio (L/S ratio) and the phosphatidylglycerol percentage in 200 samples of gastric aspirate and found an L/S ratio of 2.5 to be a satisfactory cutoff value for distinguishing fetal lung maturity and immaturity. We confirmed that the presence of phosphatidylglycerol excluded the possibility of respiratory distress.
Quantification of human apolipoprotein A-IV by "sandwich"-type enzyme-linked immunosorbent assay.
Authors: Rosseneu M , Michiels G , De Keersgieter W , Bury J , De Slypere J P , Dieplinger H , Utermann G 
Published: January 2020

Abstract
A specific and sensitive "sandwich"-type enzyme-linked immunosorbent assay (ELISA) has been developed for quantifying human apo A-IV. Using apo A-IV immunosorbent columns, we isolated monospecific anti-apo A-IV antibodies for coating the ELISA plates and for preparing peroxidase-antibody conjugate. The assay can detect as little as 0.20 ng of apo A-IV, with mean intra- and interassay CVs of 3.6% and 8.2%, respectively. The apoA-IV concentrations in normolipemic and hyperlipemic plasma were unaffected by either delipidation or treatment with detergents or urea. To validate the ELISA assay we compared it with an immunoelectrophoretic technique. ApoA-IV concentrations in plasma from normo- and dyslipemic subjects compared well by the two assays (r = 0.89). The mean apo A-IV concentration, measured by ELISA in plasma from 50 normolipemic subjects, was 143 (SD 52) mg/L; values for dyslipemic subjects were not significantly different. We also used this new assay to monitor apo A-IV profiles of normolipemic and hypertriglyceridemic plasma after chromatographic fractionation.
Reliability of IL Monarch ion-selective electrode module for sodium, potassium, and chloride measurements.
Authors: Guagnellini E , Spagliardi G , Bernardi G , Stella P 
Published: January 2020

Abstract
We evaluated the IL Monarch random-access centrifugal analyzer for measurement of Na+, K+, and Cl- by an indirect potentiometric method. For different concentrations of control material, the total precision (CV) ranged between 0.82% and 1.14% for the three electrolytes; linearity was acceptable within a range of 103 to 215 mmol/L for Na+, 1.6-15.25 mmol/L for K+, and 80-173 mmol/L for Cl-. Data correlated well with those by flame photometry for Na+ and K+ and with those by coulometry for Cl-, both for various biological materials--sera, urines, dialysis fluids--and commercial control materials from various producers. Stability of the potentiometric signal was acceptable: daily variations were 0.2 mV for Na+, 0.05 mV for K+, and 0.03 mV for Cl-. Accordingly, we conclude that the system supplies reproducible and accurate results while being easy to use and requiring little maintenance. The use of indirect potentiometry offers results consistent with those obtained with traditional methods, and easily interpretable by clinical staff. However, better information about the actual ion activity in the tested sample for certain pathologies such as hyperlipemia and dysproteinemia could be obtained by methods involving direct potentiometry.
Antidepressants in the medically ill: diagnosis and treatment in primary care.
Authors: Katon W , Roy-Byrne P P 
Published: January 2020

Abstract
Major depression is one of the most common clinical problems seen by primary-care physicians. The prevalence is 5% to 10% in primary-care outpatients and 15% in medically ill inpatients. Despite this high prevalence rate, depression is frequently not accurately diagnosed. Evidence suggests that misdiagnosis often occurs because patients with depression frequently focus preferentially on somatic complaints or amplify complaints of chronic medical illness. The tricyclic antidepressants are more effective than placebo, both in treating medically ill patients with depression and primary-care patients with major depression. Common side effects of the tricyclic antidepressants such as the anticholinergic, cardiac, and blood-pressure problems are reviewed, with emphasis on the use of specific tricyclics in medically ill populations.
Prenatal diagnosis of cystic fibrosis: microvillar enzymes and DNA analysis compared.
Authors: Buffone G J , Spence J E , Fernbach S D , Curry M R , O'Brien W E , Beaudet A L 
Published: January 2020

Abstract
We have established reference ranges for three microvillar intestinal enzymes--alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.1), and leucine aminopeptidase (EC 3.4.1.1)--measured in amniotic fluid in a reference population of 1875 women presenting for routine amniocentesis. These data were derived for use in prenatal diagnostic studies in a population at risk (1:4) for cystic fibrosis. False-positive or indeterminate results were noted for fewer than 3.5% of all low-risk cases for each enzyme evaluated. Total alkaline phosphatase and its isoenzymes and leucine amino-peptidase and gamma-glutamyltransferase were measured in amniotic fluid sampled between the 15th and 19th weeks of gestation. Restriction fragment length polymorphism analysis of DNA was also performed when possible. In 52 cases examined for cystic fibrosis thus far, 46 were diagnosed on the basis of DNA analysis and (or) by sweat testing; for the other six cases, only abnormal enzyme results were obtained before termination of pregnancy. Predictions based on microvillar enzyme results were falsely negative in three cases. In only one case was there a discrepancy between enzyme results and DNA analysis. Diagnostic accuracy was highest during the 17th and 18th week of gestation. Preliminary results suggest the false-negative rate of this diagnostic strategy may be greater than or equal to 10%.
Six direct radioimmunoassays of estradiol evaluated.
Authors: Schiøler V , Thode J 
Published: January 2020

Abstract
We evaluated the analytical performance of six commercial direct radioimmunoassays of 17 beta-estradiol, those from Radioassay Systems Laboratories, IRE Medgenix, Biotecx Laboratories, Farmos Spectria, International CIS, and Diagnostic Products Corp. The mean value for estradiol (E2) and the within- and between-run CVs were determined for serum pools and control materials, measured in seven to 10 runs with each method. Mean values for E2 in pooled sera deviated by 75% to 350% from the means measured with our routinely used extraction method. Between-run CVs ranged from 4% to 14% for the direct assays as compared with 10% for the extraction assay. We also investigated, for two of the direct assays, the effect of extraction with diethyl ether before radioimmunoassay, with respect to improvement in the agreement with our extraction method. All of the assays were easy to perform and results were obtained within 4-5 h, but we conclude that matrix effects may be expected in direct assays of estradiol.
Lack of effect of warfarin on uric acid concentration.
Authors: Walker F B , Becker D M , Kowal-Neeley B , Krongaard L S 
Published: January 2020

Abstract
Uric acid concentrations reportedly are increased in patients being treated with warfarin. We measured uric acid in 40 patients before and during warfarin administration. The mean pre- and post-warfarin uric acid concentrations for our patients were 0.39 mmol/L and 0.40 mmol/L, respectively, not a significant difference. Further observations of hyperuricemic patients started on warfarin are needed to prove that their risk of gout is not increased.
Identification of HIV-specific oligoclonal immunoglobulins in serum of carriers of HIV antibody.
Authors: Papadopoulos N M , Costello R , Ceroni M , Moutsopoulos H M 
Published: January 2020

Abstract
Zone electrophoresis on agarose gel was performed on serum samples from HIV-antibody carriers and negative controls. Nitrocellulose strips precoated with an HIV preparation were then placed on top of the gels and developed by an immunoblotting procedure. A positive reaction was demonstrated between the HIV antigens and the HIV-antibody-positive serum samples with hypergammaglobulinemia and oligoclonal IgG bands. A negative reaction was found between the HIV antigens and HIV-antibody-negative serum samples from a normal person and a patient with monoclonal gammopathy. The presence of oligoclonal IgG bands in the serum of HIV-antibody carriers, and their positive identification with HIV antigens, indicates a specific immune response of the host to the HIV infection and supports the use of oligoclonal IgG bands as markers to follow the course of HIV infection.
One-step, high-yield purification of human prostatic acid phosphatase from seminal fluid by gel-filtration HPLC under nondenaturing conditions.
Authors: Rusciano D , Agostini E , Ceccarini C , Terrana B 
Published: January 2020

Abstract
This is a fast, efficient method for purification to homogeneity of human prostatic acid phosphatase [orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2], from seminal fluid. Use of a "high-pressure" liquid-chromatographic gel-filtration column permits high-yield recovery of the purified enzyme with most of its enzymatic and immunological activity retained.
Are the classical markers sufficient to describe uremic solute accumulation in dialyzed patients? Hippurates reconsidered.
Authors: Schoots A C , Dijkstra J B , Ringoir S M , Vanholder R , Cramers C A 
Published: January 2020

Abstract
Interdependencies of accumulated solutes, analyzed by liquid chromatography in dialyzed and non-dialyzed patients, were studied by multivariate statistical analysis. In principal component analysis, three principal components (PC1-PC3) were retained from the data on 22 accumulated compounds in dialyzed patients, whereas only one principal component was retained from analogous data of a non-dialyzed patient group. PC1 in the dialyzed patient group comprises concentrations of hippuric acid, p-hydroxyhippuric acid, tryptophan, and five unidentified fluorescent solutes in serum. Concentrations of the classical markers urea, uric acid, creatinine, and phosphate were closely related to PC2 in these patients. Indoleacetic acid and two unidentified fluorescent compounds constitute PC3. The compounds associated with the groups found by principal component analysis may be characterized by chemical structure and by the mechanism of their excretion via the remaining nephrons of dialyzed patients. In the non-dialyzed group, most of the solutes could be described by a single PC. This PC and PC1 from the dialyzed group correlated significantly with residual renal function, and with total ultraviolet absorbance and total fluorescence emission. The data suggest that it is of value to introduce a marker of uremic solute retention in addition to urea, to account for renal-function-related "organic-acid-like" compounds that are excreted by renal tubular secretion in dialyzed patients. The hippurates may serve this purpose.
An enzymatic method for erythrocyte acetylcholinesterase.
Authors: Abernethy M H , Fitzgerald H P , Ahern K M 
Published: January 2020

Abstract
The acetylcholinesterase (EC 3.1.1.7) in 50 microL of a 61-fold dilution of erythrocytes in water hydrolyzes acetylcholine during a timed 20-min reaction at 37 degrees C. The resulting choline is measured by use of choline oxidase coupled to peroxidase, with phenol and aminoantipyrene to give a pink product that absorbs maximally at 500 nm. For calibration, a choline iodide standard is included in each batch of up to 19 samples. Accuracy was assessed by using specific inhibitors and measuring choline in the presence of excess erythrocyte solution. The standard curve for the assay is linear to threefold the normal enzyme activity. Between-batch precision was 0.40 kU/L at a mean of 11.5 kU/L (CV 3.5%), and comparison with an acetylthiocholine procedure (x) gave a good correlation: y = 1.02x - 0.27 kU/L (r = 0.991). Long-term precision (10 months), assessed from three sets of assays of samples from 17 individuals, was 0.71 kU/L at a mean of 11.7 kU/L (CV 6.1%).
Development of standard materials for use with the hematofluorometer.
Authors: Parsons P J , Meola J R , Mitchell D G 
Published: January 2020

Abstract
Two methods for preparing erythrocytes were evaluated for the purpose of developing stable, blood-based standard materials for the hematofluorometer. Erythrocytes washed with citrate-phosphate-dextrose solution and reconstituted with platelet-free plasma were stable for 12 weeks. Plasma-free erythrocytes washed with isotonic saline and resuspended in citrate-glycerol solution were stable for 18 weeks when stored at 4 degrees C. Consequently, plasma-free erythrocytes were successfully used as proficiency test specimens in the New York State Department of Health's Clinical Laboratory Evaluation Program for hematofluorometer users.
Potassium permanganate used to eliminate interference with the Porter-Silber reaction in the butanol extraction method for determination of urinary 17-hydroxycorticosteroids.
Authors: Maeda T , Matsuzaki H , Sekine T 
Published: January 2020

Abstract
We describe a simple, rapid, and less interference-susceptible method for using the Porter-Silber reaction for determination of urinary 17-hydroxycorticosteroids. The procedure is based on butanol extraction of the steroids after the urine sample is treated with potassium permanganate and sodium bisulfite. These treatments, together with an additional acid- and alkali-washing of the extract, could eliminate most of the substances in urine that interfere with the Porter-Silber reactions. Values so obtained correlated well (r = 0.95) with those by Furuya's method in which beta-glucuronidase is used. Our method may be useful and suitable for a screening test of adrenocortical and pituitary functions.
Inaccuracy in measuring glycated albumin concentration by thiobarbituric acid colorimetry and by boronate chromatography.
Authors: Johnson R N , Baker J R 
Published: January 2020

Abstract
We compared thiobarbituric acid colorimetry and boronate chromatography for measuring glycation of serum proteins. With 14C-glycated human albumin as a test material, both methods were acceptably linear and precise. However, comparable estimates (mmol/L) of albumin glycation ranged from 0.22 for thiobarbituric acid to 0.05 for boronate, representing yields relative to [14C]glycosylprotein of 42% and 10%, respectively. The low yield with thiobarbituric acid was corroborated independently on the basis of kinetic differences between the reactions of fructose standards and of glycosylprotein, leading to underestimation of glycosylprotein concentration. The lower estimate of glycosylprotein by boronate chromatography was related to an apparent requirement for two [14C]glyco groups per albumin molecule to effect binding.