bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of lactate dehydrogenase isoenzymes by sodium perchlorate evaluated
Authors: Sanders G T , van der Neut E , van Straalen J P 
Published: January 2020

Abstract
We evaluated a method of measuring lactate dehydrogenase isoenzyme 1 (LD-1) selectively (Clin Chem 1987;33:991-2), in which all other LD isoenzymes were inhibited by adding sodium perchlorate to the reaction medium to a final concentration of 0.825 mol/L. In this study we used the different isoenzymes purified from human autopsy tissue and found that the originally published amount of inhibitor (a) increased the original LD-1 activity and (b) did not eliminate all enzyme activity of LD-2 and LD-3. Interference by LD-2 was further demonstrated. Thus we conclude that this method cannot be used for the selective determination of LD-1 because its results do not accurately reflect the original LD-1 activity.
Effect of occupational lead exposure on lymphocyte enzymes involved in heme biosynthesis
Authors: Rossi E , Costin K A , Garcia-Webb P 
Published: January 2020

Abstract
Lead exposure is a well-known cause of increases in urinary coproporphyrin and erythrocyte zinc-protoporphyrin, so these compounds are often used to monitor occupational lead exposure. The increased concentrations are usually assumed to result from lead inhibition of two of the mitochondrial enzymes of heme biosynthesis, coproporphyrinogen oxidase (EC 1.3.3.3) and ferrochelatase (EC 4.99.1.1). We studied 88 subjects in whom the degree of occupational lead exposure was established by measuring erythrocyte lead and protoporphyrin. Assay of lymphocyte coproporphyrinogen oxidase and ferrochelatase activities showed that these enzymes were unaffected by lead exposure, as was a related enzyme, lymphocyte NADH-ferricyanide reductase. We propose alternative explanations for the increased concentrations of coproporphyrin and zinc-protoporphyrin seen in lead exposure.
Development and evaluation of a simplified dot-blot method for detecting the delta F508 mutation in cystic fibrosis
Authors: Skogerboe K J , West S F , Murillo M D , Tait J F 
Published: January 2020

Abstract
The recent discovery of the cystic fibrosis gene enables DNA-based testing for the direct identification of the deletion of three basepairs coding for phenyalanine at codon 508, the major mutation responsible for the disease. This mutation can be detected by analysis of amplified DNA with allele-specific oligonucleotide probes. We have simplified the procedure of Kerem et al. (Science 1989;245:1073-80) so that the assay can be routinely completed in one working day, starting with an extracted DNA sample. Addition of salmon-sperm DNA to the product of the polymerase chain reaction greatly improved the quality of the hybridization signal. The precision of the method was evaluated by blind analysis and interpretation of results for 100 specimens from 25 patients. The same result was obtained for each patient analyzed separately four times, and four independent observers agreed on the interpretation of results for all 100 specimens. No specimen required repeat analysis to produce interpretable results. We conclude that this method is reliable and convenient for routine clinical laboratory use.
Macro creatine kinase in a case of carnitine palmitoyltransferase deficiency
Authors: Deguchi H , Sugiyama N , Kawamura H , Uemura T , Shimizu A , Yamamoto M 
Published: January 2020

Abstract
A stout man was admitted to the hospital with acute rhabdomyolysis associated with macro creatine kinase (macro-CK, EC 2.7.3.2). This anomaly of CK was detected by gel electrophoresis as an atypical band between CK-MB and CK-MM, classified according to Stein's criteria (Clin Chem 1982; 28:19-24) as type 1, and identified by immunofixation electrophoresis as containing CK isoenzymes MM and MB and immunoglobulin A. Muscle biopsy showed that the etiology of rhabdomyolysis in this case was deficiency of carnitine palmitoyltransferase (CPT, EC 2.3.1.21) in the muscle. We report the first observation of macro-CK in a case of CPT deficiency; its presence may result from recurrent rhabdomyolytic attacks owing to CPT deficiency, and may suggest underlying enzymic abnormality in muscle.
Kinetic measurement of bicarbonate in serum by thiocyanate inhibition of wheat germ phosphoenolpyruvate carboxylase
Authors: Punzalan R R , Johnson G F , Cunningham B A , Feld R D 
Published: January 2020

Abstract
We describe a kinetic enzymic method for serum bicarbonate analysis, using wheat germ phosphoenolpyruvate carboxylase (EC 4.1.1.31) coupled through oxaloacetate reduction with NADH in the presence of malate dehydrogenase (EC 1.1.1.37). Inhibition with potassium thiocyanate yielded first-order kinetics with respect to bicarbonate over the concentration range of 0-45 mmol/L. The inhibitor was chosen by evaluating reaction data in the presence of different anions, with use of a monoexponential model. Criteria for first-order kinetics included a constant reaction half-life over the concentration range and SDest for the model comparable with the magnitude of spectrophotometric noise. We compared our kinetic method (y) with an automated ion-selective electrode method (x), obtaining the regression relationship y = 0.97x + 1.2 mmol/L (r = 0.991; n = 77; mean = 25.5 mmol/L; y = 25.3 mmol/L). Within-run precision from duplicates was 3.1% (mean = 25.2 mmol/L; n = 72). Total analytical precision (n = 12) was 9.4% (mean = 15 mmol/L) for the low control and 4.3% (mean = 32 mmol/L) for the high control. We conclude that the kinetic assay allows use of large serum-to-reagent ratios (1:100) and smaller amounts of NADH than an equilibrium assay. The assay is suitable for automated kinetic analysis.
Assay of functional activity of alpha 1-antichymotrypsin in plasma
Authors: Heidtmann H H , Müller J , Havemann K 
Published: January 2020

Abstract
We introduce a novel assay for measuring active alpha 1-antichymotrypsin (alpha 1X) in human plasma. The assay works on the principle that cathepsin G, immobilized in microtiter plates, preferentially binds alpha 1X, which then can be specifically quantified immunologically. alpha 1X activity can be detected even after 50,000-fold dilution of normal plasma. A linear range was defined for reproducible quantification. There was no interference by alpha 1-proteinase inhibitor or alpha 2-macroglobulin. The assay is designed to detect conditions having decreased alpha 1X activity to further elucidate the biological function of this prominent acute-phase protein.
Polyol concentrations in serum during hemodialysis
Authors: Roboz J , Kappatos D , Holland J F 
Published: January 2020

Abstract
Polyol concentrations were determined by selected-ion monitoring in 10 sample sets taken before dialysis and hourly for 4 h during dialysis. Predialysis concentrations (mumol/L) exceeding the upper limit of normal (mean + 2 SD; n = 33) were found for erythritol (25.4-59.0), threitol (11.5-46.7), and arabinitol (21.0-49.3) in all 10 cases; mannitol (2.7-62.0) in nine cases; and xylitol (0.7-1.3) in eight cases. Concentrations of adonitol, galactitol, and sorbitol were all within normal limits. During dialysis, the concentration of six polyols decreased by approximately 50%, but there were no significant changes for xylitol and adonitol. Erythritol, threitol, and arabinitol concentrations remained more than double the upper limit of normal in all patients after 4 h of dialysis. High residual concentrations were found for mannitol (seven cases) and xylitol (six cases). The results suggest fundamental differences in the homeostasis as well as the dialyzability of different polyols. The potential toxic significance of the high residual concentrations after a 4-h dialysis needs to be investigated.
Insufficient accuracy and specificity of polyanion precipitation methods for quantifying low-density lipoproteins
Authors: Siekmeier R , März W , Gross W 
Published: January 2020

Abstract
Recently, polyanion precipitation assays for low-density lipoprotein (LDL)-cholesterol have been found to underestimate their analyte in normolipidemic samples (Siekmeier et al., Clin Chim Acta 1988;177:221-30). Therefore, accuracy, specificity, and interference by nonesterified fatty acids have been studied for three precipitants (obtained by heparin, dextran sulfate, or polyvinyl sulfate precipitation). At normal concentrations of LDL, precipitation is incomplete, whereas it is nearly quantitative at high concentrations of LDL. The polyvinyl sulfate reagent markedly responds to variations in the amount of non-LDL protein present in the precipitation mixture. In the dextran sulfate and the polyvinyl sulfate method, but not in the heparin method, the percentages of LDL precipitated notably increase as the concentration of the polyanion compound is decreased. In either assay, very-low-density lipoproteins, but not high-density lipoproteins, are significantly coprecipitated (dextran sulfate 28%, polyvinyl sulfate and heparin 66%) in a concentration-independent fashion. Increased concentrations of nonesterified fatty acids markedly interfere with the dextran sulfate and polyvinyl sulfate assay, but do not much affect results with the heparin reagent.
Determination of carrier status in Duchenne and Becker muscular dystrophies by quantitative polymerase chain reaction and allele-specific oligonucleotides
Authors: Prior T W , Papp A C , Snyder P J , Highsmith W E , Friedman K J , Perry T R , Silverman L M , Mendell J R 
Published: January 2020

Abstract
Detection of carriers of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), in the deletion cases, involves calculating gene dosage from Southern blots. We show that the analysis of dosage can also be made from the polymerase chain reaction (PCR) with use of allele-specific oligonucleotides (ASOs). The deletion-prone exons are amplified, transferred to a membrane, and hybridized with ASOs complementary to the exons; the autoradiographic bands are then quantified with a densitometer. After determining the quantitative conditions of the amplification reaction, we were able to identify deletions in a DMD/BMD carrier female. The determination of carrier status via PCR removes several of the technical limitations of Southern analysis and is also cost- and labor-effective.
Monitoring free digoxin instead of total digoxin in patients with congestive heart failure and high concentrations of digoxin-like immunoreactive substances
Authors: Dasgupta A , Saldana S , Heimann P 
Published: January 2020

Abstract
Digoxin-like immunoreactive substances (DLIS) are present in patients with conditions associated with volume expansion (including hypervolemic hypertension, renal failure, and liver failure) and in pre-eclampsia and premature birth. These strongly-protein-bound substances cross-react with anti-digoxin antibodies and cause falsely increased measured concentrations of digoxin in serum. Patients with congestive heart failure (CHF) often have volume expansion and are receiving digoxin therapy. They are also very sensitive to digoxin toxicity and have a very narrow therapeutic range (1.0-1.9 nmol/L). We found monitoring the concentrations of free digoxin (in protein-free ultrafiltrates) helpful in eliminating the interferences of DLIS in CHF patients. DLIS concentrations were measured by fluorescence polarization assay. Concentrations of DLIS were detectable in significantly more (58.3%) of the 12 CHF patients (group A) who were not receiving digoxin than in the 22 normal volunteers tested (13.6%) (P less than 0.05 by both chi-square and Fisher's exact test). Protein-free filtrates from patients or normal volunteers did not show any measurable DLIS activities. We also determined the concentrations of total and free digoxin in 12 patients with CHF who were receiving digoxin (group B) and compared the results with those for 22 patients receiving digoxin without the diagnosis of CHF or any known pathological conditions that could increase DLIS concentrations. The ratio of free to total digoxin in patients in group B was significantly lower (mean = 52.8%, SD 10.2%) than in those receiving digoxin (mean = 72.7%, SD 6.5%) for other reasons (independent two-tailed t-test, P less than 0.05).
Semi-automated colorimetric method for measuring glycohemoglobin, with reduction of nitroblue tetrazolium, evaluated
Authors: Hill R P 
Published: January 2020

Abstract
I evaluated a semi-automated method for measuring glycohemoglobin via reduction of nitroblue tetrazolium by acetone-extracted globin. The simultaneous measurement of glycated protein and total protein with the Roche Mira S analyzer showed good analytical precision (between-batch CV 3.5%-8.5%). Correlation of results (y) with those by a boronate affinity chromatography method (x) gave a regression line of y = 2.0x + 5.9 for samples from patients attending a diabetic outpatient clinic. I also studied reaction kinetics; chloromercuribenzoate concentration, sample volume, and detergent concentration affect the reaction, probably by modulating the reduction of dye by globin-thiol groups.
Variation in concentration of lipids, lipoprotein lipids, and apolipoproteins A-I and B in plasma from healthy women
Authors: Brown S A , Boerwinkle E , Kashanian F K , Swanson N , Patsch W 
Published: January 2020

Abstract
The components of total variation--biological, inter- and intra-individual, and analytical--of plasma lipids, lipoprotein lipids, and apolipoproteins A-I and B have been determined in a population of 44 healthy women, ages 18-35 years. Blood was sampled three separate times at three-month intervals, with no restrictions on diet or physical activity during these periods. The greatest inter-individual variances were observed for high-density lipoprotein (HDL)-cholesterol, HDL2-cholesterol, and total plasma cholesterol. Triglycerides had the highest intra-individual variance (CV 22%). The percentage of inter- and intra-individual variances of apolipoprotein A-I concentrations were more reflective of total HDL- and HDL2-cholesterol content than of HDL3-cholesterol. Concentrations of calculated low-density-lipoprotein cholesterol showed a greater inter-individual variation (18.6%) than did apolipoprotein B (10.7%). The laboratory CVs for these analytes were similar to other reported values. From these data, we computed the expected variation for subjects in our study for single and repeated measurements. Such considerations can influence decision-making in the clinical setting or in designing epidemiological studies.
Development of an enzyme-linked immunosorbent assay with a monoclonal antibody prepared against alpha 1-antitrypsin for diagnostic screening of inflammatory disorders
Authors: Silvestrini B , Guglielmotti A , Saso L , Milanese C , Melanitou E , Grima J , Cheng C Y 
Published: January 2020

Abstract
A monoclonal antibody, designated A2a18b8, of IgG1 class prepared against human alpha 1-antitrypsin, cross-reacts with alpha 1-antitrypsin in the serum of rat and baboon, but not with alpha 1-antitrypsin in serum of rabbit, pig, hamster, guinea pig, dog, or turtle. We used A2a18b8 in an enzyme-linked immunosorbent assay (ELISA) developed for human alpha 1-antitrypsin. Preliminary ELISA screening of 247 serum samples from patients with various inflammatory disorders indicated that the concentration of a specific epitope(s) on alpha 1-antitrypsin recognized by this monoclonal antibody was increased significantly in patients with active systemic lupus erythematosus, mixed connective tissue disease, and rheumatoid arthritis, but not in patients with sclerodermic disorders or Sjögren's syndrome. Evidently, A2a18b8 has diagnostic value in that it selectively recognizes a specific epitope(s) on alpha 1-antitrypsin that is (are) apparently exposed during selective inflammatory disorders.
Effects of analytical method and lyophilized sera on measurements of apolipoproteins A-I and B: an international survey
Authors: Smith S J , Henderson L O , Hannon W H , Cooper G R 
Published: January 2020

Abstract
In 1987 a collaborative study was initiated with 140 laboratories worldwide to evaluate the effects of analytical method and lyophilization on the measurement of different concentrations of apolipoproteins (apo) A-I and B in four lyophilized serum pool samples. This survey confirmed that the lyophilized apo Reference Material of the International Union of Immunological Societies (IUIS) is useful for apo A-I assays as an international serum-based reference material, because among-method variation is negligible. The apo A-I concentration value of 1.24 g/L is now assigned to the IUIS Reference Material (CDC 1883) by a Centers for Disease Control RIA in-house reference method. Use of lyophilized serum preparation as a reference material for some modes of apo B measurement is questionable because of lyophilization and matrix effects. Both radial immunodiffusion and liquid immunoprecipitin methods demonstrated bias in measured apo B concentrations, compared with overall method-weighted means values on the IUIS Reference Material. Because of the uncertainty associated with LDL primary standard, protein analysis, and concentration differences among analytical methods, assigning a single apo B concentration value to the IUIS Reference Material appears inadvisable at present.
Improved kinetic rate assay of urinary N-acetyl-beta-D-glucosaminidase with 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide as substrate
Authors: Makise J , Saito E , Obuchi M , Kanayama M , Harakawa K , Yoshida K 
Published: January 2020

Abstract
We have improved the kinetic rate assay method for determining N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) activity in urine with use of the synthetic substrate, 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide (CNP-NAG), reported previously (Clin Chem 1988;34:2140-2). To increase the solubility of this substrate, we used crown ether (15-crown-5-ether) and ethylene glycol. In addition, we used for the standard solution NAG from human placenta, with specificity corresponding to that of human urine, so that values obtained with the CNP-NAG method and a p-nitrophenyl-NAG method ("MEI Assay NAG") correlated almost completely (r = 0.995, n = 29). Reference values for urinary NAG activity determined by the CNP-NAG method were established for untimed urine specimens from 674 healthy volunteers. The normal reference interval (mean +/- 2 SD) for NAG: 1.6-15.0 (mean 4.9) U per gram of creatinine.
Hyponatremia in patients admitted to a coronary care unit
Authors: Evans J R , McIntosh J P , McIntosh H J , Mitchell P E 
Published: January 2020

Abstract
Calculation of osmolal gap in plasma and urine samples from patients after acute myocardial infarction was carried out to see whether changes in these variables support the concept of a "sick-cell" mechanism being responsible for the hyponatremia associated with acute myocardial infarction. Some supportive evidence was found on the first day after admission but, overall, the evidence was not convincing.
Increased sensitivity in a radioimmunoassay for measuring cyclosporine in lipoprotein fractions
Authors: Brunner L J , Yau J C , Lautersztain J , Luke D R 
Published: January 2020

Abstract
We describe a modification of the commercially available cyclosporine (CAS) 3H-RIA kit, allowing detection of drug in lipoprotein fractions obtained by ultracentrifugation. Sodium bromide solutions containing the lipoprotein fractions were dried and reconstituted with drug-free plasma. Methanolic extractions were centrifuged, and 250 microL of the supernate was dried and reconstituted with 50 microL of methanol. Buffer, radioactive tracer, and monoclonal antibody were then added and incubated for 2 h at 4 degrees C. Samples were subjected to charcoal de-activation and then centrifuged, and the radioactivity in the supernate was counted. The limit of detection of CSA was 2.5 micrograms/L; analytical recovery was between 97.5% and 101.3%. Within- and between-day CVs were less than 9%. We conclude that the present method may be beneficial for therapeutic drug monitoring of CSA in lipoprotein fractions.
Simple enzymatic assay for determining cholesterol concentrations in bile
Authors: Luhman C M , Galloway S T , Beitz D C 
Published: January 2020

Abstract
We use bilirubin oxidase (EC 1.3.3.5) to remove interference by bilirubin in the assay of cholesterol concentration in bile by standard enzymatic methods. Samples are treated for 10 min with nonlimiting amounts of bilirubin oxidase to form biliverdin from bilirubin before the reagent for cholesterol is added. The relatively small interference by biliverdin is easily eliminated by use of sample blanks. The method is simple, convenient, and not hampered by the "chromogen oxidase" activity (the inherent ability of bilirubin oxidase to oxidize some chromogens) that plagues other assays of this type. Using this assay, we have accurately and precisely determined the concentration of cholesterol in bile. Such elimination of bilirubin will also be useful in assays of other biliary constituents or constituents of urine or icteric plasma.
Validation of highly specific and sensitive radioimmunoassays for lutropin, follitropin, and free alpha subunit in unextracted urine
Authors: Landy H , Schneyer A L , Whitcomb R W , Crowley W F 
Published: January 2020

Abstract
Measurement of the urinary excretion of lutropin (LH) and follitropin (FSH) and their common free alpha subunit (FAS) assists in monitoring the maturation of the hypothalamic-pituitary-gonadal axis and in understanding the physiology of the pituitary glycoprotein hormones. Here we describe sensitive, specific polyclonal radioimmunoassays for LH and FSH and a monoclonal radioimmunoassay for FAS for use with urine--assays unperturbed by alterations in urinary pH or osmolarity within the broad physiological range encountered in urine. Concordance between LH, FSH, and FAS concentrations in extracted and unextracted urine samples was high. Linearity and parallelism with the standard curves was observed with addition of 25 to 200 microL of unextracted urine. No effect on glycoprotein concentration was seen after as many as 10 freeze-thaw cycles. The need for extraction was further obviated by the high sensitivity of each assay, reflected by minimum detectable doses well below the concentrations encountered in patients' samples. Thus we have measured gonadotropins in unextracted urine as precisely as in extracted urine. We also have demonstrated an equally versatile assay for urinary alpha subunit, using a monoclonal antibody of high specificity for this monomer in its free, uncombined form. These radioimmunoassays complement assays of gonadotropins and free alpha subunit in serum and will allow longitudinal investigations otherwise limited by the constraints of the patient's blood volume.
Serum angiotensin-converting enzyme in healthy and sarcoidotic children: comparison with the reference interval for adults
Authors: Bénéteau-Burnat B , Baudin B , Morgant G , Baumann F C , Giboudeau J 
Published: January 2020

Abstract
Angiotensin-converting enzyme (ACE) was measured in serum of 187 healthy children between the ages six months and 18 years. Results were pooled for five-year age intervals and compared with the reference values for adults that we previously determined [Clin Chem 1986;32:884-6). Results for each age group were also studied as a function of sex. Children had higher ACE activities in serum than did adults (P less than 0.001), but these activities were age-related only from age four to 18 years. Adolescents showed sex-related differences, with higher serum ACE activities in boys than in girls (P less than 0.05). Both sex- and age-related differences may be related to a steroid hormonal regulation of ACE biosynthesis. We also verified that children with sarcoidosis (n = 20) had significantly increased serum ACE activity. Such physiological variations in serum ACE activity must be taken into account for diagnosing sarcoidosis in children, for following the course of the disease, and for evaluating the accuracy of therapy.