bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erythrocyte porphobilinogen synthase activity as an indicator of lead exposure in children.
Authors: Chisolm J J , Thomas D J , Hamill T G 
Published: January 2020

Abstract
The European standardized method for measuring porphobilinogen synthase (PBGS, EC 4.2.1.24) activity in peripheral erythrocytes is widely used in epidemiological studies of low-level Pb absorption. We have modified it to include activation with dithiothreitol (DTT). In children with concentrations of Pb in whole blood ranging from 0.29 to 1.93 mumol/L, we found the following statistically significant correlations (r): blood Pb vs nonactivated PBGS activity = -0.773 (p less than 0.005); blood Pb vs DTT-activated PBGS activity = -0.265 (p less than 0.005); blood Pb vs the ratio of DTT-activated/nonactivated PBGS activity = +0.818 (p less than 0.005). At a DTT-activated/nonactivated PBGS activity ratio of 1, which indicates no Pb-dependent inhibition of PBGS, a corresponding blood Pb concentration of 0.24 mumol/L (50 micrograms/L) would be predicted. In individuals with hematological disorders, the DTT-activated/nonactivated ratio better predicted blood concentration of Pb than did the nonactivated PBGS activity, and largely compensated for the high variability in PBGS activity. We also describe techniques to minimize contamination by Zn and Pb and to stabilize enzyme activity during collection, transport, storage, and analysis of samples.
Highly sensitive immunoenzymometric assay for human thyrotropin.
Authors: Watanabe Y , Amino N , Tamaki H , Aozasa M , Tachi J , Endo Y , Miyai K 
Published: January 2020

Abstract
A sensitive assay procedure for immunoenzymometric assay of serum thyrotropin (TSH) was developed by making several modifications of the Enzymun-Test TSH kit (Boehringer, Mannheim GmbH). Serum samples were first incubated in plastic tubes precoated with monoclonal antibodies specific to the beta subunit of human TSH. After the tubes were washed, the TSH bound to the tubes was detected with peroxidase-conjugated polyclonal antibodies to TSH. The sensitivity of the assay was 0.2 milli-int. unit/L, and the intra-and interassay CVs were less than 10%. Analytical recovery was 96 to 106%. The normal basal range of TSH was 0.5 to 4.8 milli-int. units/L. The basal levels of TSH in all but one of 48 thyrotoxic patients with Graves' disease were less than 0.2 milli-int. unit/L, clearly different from those of normal subjects. Thyrotoxic patients in early normal pregnancy showed TSH concentrations of 1.7 to 2.9 milli-int. units/L by conventional double-antibody radioimmunoassay, possibly from cross reactivity with human choriogonadotropin, but undetectable TSH by this method. Measurement of basal TSH by this sensitive assay can be used as an initial screening test for thyroid dysfunction.
Steroid profiling--an update.
Authors: Schmidt N A , Borburgh H J , Penders T J , Weykamp C W 
Published: January 2020

Abstract
Extraction of steroids from urine with C18 solid-phase extraction cartridges results in an extract containing impurities. If, during the extraction of hydrolyzed urine, an amino (NH2) column is placed in series with the C18 column, then one obtains a sample that is sufficiently clean for gas-chromatographic analysis. Analytical recovery of dehydroepiandrosterone from urine is considerably decreased by the use of increasing amounts of Helix pomatia enzyme preparation. Extraction of the steroid conjugates from urine with C18 columns before the hydrolysis stage is essential for hydrolysis with an amount of enzyme preparation that suffices for complete splitting of the polar steroid conjugates but not so much as to cause insufficient analytical recovery of dehydroepiandrosterone.
Identification of hyperthyroid patients by means of a sensitive assay for thyrotropin.
Authors: Malter J S , Manotti S E , Knee G R , Goodman D B , Strauss J F 
Published: January 2020

Abstract
We evaluated a new assay (TSH3 MAIAclone) for thyrotropin (TSH) with improved sensitivity, testing a series of hospital inpatients with increased free thyroxin indices (thyroxin concentration X triiodothyronine uptake on resin). This assay involves use of three monoclonal antibodies and an antibody-magnetic particle conjugate that rapidly and completely separates bound and free tracer in a magnetic field. The assay turnaround time is 3 h. By the TSH3-MAIAclone assay, 65% of these patients with an increased free thyroxin index were identified on the basis of a TSH value less than or equal to 0.50 milli-int. unit/L. In contrast, another commercially available assay for TSH detected suppressed TSH concentrations in less than 5% of these patients. We conclude that the TSH3 MAIAclone assay markedly improves our ability to discriminate hyperthyroidism from euthyroidism.
The clinical use of laser-excited fluorometry.
Authors: Sepaniak M J 
Published: January 2020

Abstract
Many areas of spectroscopy have benefited from the use of laser radiation sources. I present a discussion of the basic properties of the laser and how these properties can be advantageous when laser excitation is used in fluorometry. Although the laser has not yet been accepted as a routine instrument in the clinical laboratory, its unique properties have rendered it useful in several analytical methodologies that are based on fluorometry and used in the clinical or biological fields. Accordingly, I briefly review the practical aspects of some clinical applications of laser-excited fluorometry.
Liquid-chromatographic measurement of purine nucleotides in blood cells.
Authors: Boulieu R , Bory C , Gonnet C 
Published: January 2020

Abstract
In this anion-exchange "high-performance" liquid-chromatographic method of analysis for purine nucleotides, the nucleotides are separated with high efficiency and selectivity on a weak anion exchanger (Hypersil APS 2, 3-micron particle size) by elution with a gradient of eluent pH and concentration. Applying this method to analysis for these compounds in human blood cells, we determined them in a patient with adenosine deaminase deficiency who was treated with a bone-marrow transplantation, finding that the transplantation did not entirely correct the patient's abnormalities of purine metabolism.
Six methods for isolating high-density lipoprotein compared, with use of the reference method for quantifying cholesterol in serum.
Authors: Wiebe D A , Smith S J 
Published: January 2020

Abstract
Using 90 serum specimens, we compared six routine procedures for high-density lipoprotein (HDL) isolation to determine the biases, if any, of each. Use of the Reference Method for cholesterol (Duncan et al., Centers for Disease Control, Atlanta, GA) and automated dispensing equipment helped ensure the accuracy of the cholesterol measurements and minimized errors from sample and reagent manipulations. Regression analysis of the results showed significant differences between most HDL isolation methods, except for those involving precipitation with heparin-MnCl2 (1.0 mol/L) or polyethylene glycol 6000, which yielded comparable results with a slope close to one and a zero intercept. The dextran sulfate (Mr 500 000)-MgCl2 method had the largest proportional and constant bias with respect to those two methods. All the methods produced comparable results in the clinically important low HDL-cholesterol range (250 to 350 mg/L), but biases were significant at high concentrations. We conclude that these increased biases in the upper ranges of HDL-cholesterol concentrations are the result of increased heterogeneity of HDL and the different mechanisms involved in forming the insoluble complexes between lipoproteins and the various precipitation reagents.
Comparisons of 17 lots of 2-oxoglutarate, and specifications for use of this substrate in reference methods.
Authors: Bowers P N , Bowers G N , McComb R B 
Published: January 2020

Abstract
We examined 17 lots of 2-oxoglutarate (seven acid forms, three K salt forms, and seven Na salt forms), obtained from eight commercial suppliers, for suitability for measuring aspartate aminotransferase (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2) in human serum. Measurements of the catalytic activity concentrations of these two aminotransferases with each of these 17 preparations were not sufficiently sensitive to distinguish good from poor-quality material. Thus, we ranked these lots for purity, by specific analysis with glutamate dehydrogenase and by liquid chromatography, and determined the water content, acid content, and spectral characteristics of each. On the basis of a 2-oxoglutarate assay value by glutamate dehydrogenase of 98% or greater, we considered seven of the preparations acceptable and 10 unacceptable. The molar absorptivities (L X mol-1 X cm-1, mean +/- SD) of the seven acceptable lots in 1 mol/L HCl were: epsilon 325 nm = 9.12 +/- 0.02 (CV = 0.2%), epsilon 279 nm = 2.63 +/- 0.23 (CV = 9.9%), and epsilon 245 nm = 37.9 +/- 4.1 (CV = 10.9%). Use of these spectrophotometric limits alone unambiguously distinguished the inferior lots of 2-oxoglutarate. We urge the inclusion of detailed spectrophotometric specifications for 2-oxoglutarate in Reference Methods for aminotransferase measurements.
Routine "cardiac" and "hepatic" serum enzyme profiles in cardiac-transplant patients treated with cyclosporine A: operative and post-operative findings.
Authors: McKenzie F N , Moses G C , Henderson A R 
Published: January 2020

Abstract
We report representative serum enzyme changes after cardiac transplantation in 20 patients receiving post-transplant therapy with cyclosporine. In general, the changes resembled those after acute myocardial infarction or coronary artery bypass surgery, but were more prolonged. Cardiac biopsy or episodes of cardiac rejection did not usually alter serum enzyme activities. Cyclosporine A toxicity appeared to be responsible for increases in serum transaminases (alanine and aspartate) and lactate dehydrogenase-5 activities. Serum gamma-glutamyltransferase activities were intermittently, and inexplicably, increased for months after the transplant.
A clinical evaluation of automated chromogenic tests as substitutes for conventional prothrombin time and activated partial thromboplastin time tests.
Authors: Duncan A , Bowie E J , Owen C A , Fass D N 
Published: January 2020

Abstract
Automated procedures involving a chromogenic substrate sensitive to thrombin-sarcosine-Pro-Arg p-nitroanilide were compared with conventional tests for prothrombin times and activated partial thromboplastin times (APTT) and with specific assays for factors V, VII, VIII, IX, X, XI, and XII. The reproducibility and sensitivity of the chromogenic tests were compared with those of the clotting tests. Further, we have confirmed that the chromogenic test for APTT is sensitive to factor VII deficiency, unlike the clotting test for APTT. This might be an advantage in monitoring orally anticoagulated patients. The ready availability of the automated equipment for performing the chromogenic tests suggests their potential for routine use. However, some discrepant results in certain patients with liver disease and in others with factor VIII inhibitors warrant caution.
Development and evaluation of a radioimmunoassay for Arg8-vasopressin, after extraction with Sep-Pak C18.
Authors: Ysewijn-Van Brussel K A , De Leenheer A P 
Published: January 2020

Abstract
We describe a specific double-antibody radioimmunoassay for measuring arginine vasopressin (AVP) in human plasma. Antisera of high avidity were obtained from rabbits that had been injected with AVP coupled to bovine thyroglobulin. The antibody reacts with both the tripeptide tail and the pentapeptide ring of the molecule, thereby eliminating cross reaction with oxytocin. Synthetic AVP was labeled with 125I by a modification of the Chloramine-T technique. The specific activity of the labeled hormone was 29 MBq/micrograms of AVP, as estimated by self-displacement analysis. The assay involves Sep-Pak C18 extraction of acidified (pH 4) plasma. Recovery of [3H]AVP added to plasma averaged 86.6 (SD 6.1)% (n = 14). Dilution curves for plasma showed linearity of response with concentration. The overall sensitivity was 0.3 ng/L when 2-mL plasma samples were extracted. The intra-assay CV was 7.8% at 4.8 ng/L (n = 12) and the interassay CV was 12.3% (n = 16) and 6.3% (n = 14) at 2.7 and 4.1 ng/L concentrations, respectively.
Urinary adenylate kinase activity as a predictor of renal allograft crises.
Authors: Bernstein L H , Russell P J , Horenstein J M 
Published: January 2020

Abstract
We examined data on adenylate kinase (EC 2.7.4.3) activity and other clinical chemical values from patients with renal transplants by analysis of variance and discriminant analysis, using various combinations of variables in an attempt to find a predictor of transplant rejection. Some typical data are presented. We conclude that the combination of urinary adenylate kinase and creatinine clearance is the best predictor for identifying patients with transient or destructive renal transplant crises.
Liquid-chromatographic determination of chloride in sweat from cystic fibrosis patients and normal persons.
Authors: Pillion D J , Meezan E 
Published: January 2020

Abstract
Chloride concentrations in sweat were measured by "vacancy liquid chromatography," a technique in which anions eluting from an ion-exchange column in the presence of an elution buffer which absorbs at 280 nm cause a decrease in absorbance proportional to the concentration of the anion. Less than 1 microL of sweat suffices for this analysis, which takes 5 min per sample. Results were comparable to those obtained by conventional titrimetric determination of chloride. Sweat from cystic fibrosis patients had higher (104 +/- 26 mmol/L) chloride concentrations than sweat from normal persons (16 +/- 7 mmol/L). This technique can be used in the diagnosis of cystic fibrosis.
A cost-effective system for performing therapeutic drug assays. I. Optimization of the theophylline assay.
Authors: Sung E , Neeley W E 
Published: January 2020

Abstract
We have developed a cost-effective system for performing drug assays by using the COBAS BIO centrifugal analyzer and EMIT reagents. With the theophylline assay as a model, we were able to optimize both instrument and chemical parameters to allow assay of 2470 samples with a 100-test EMIT kit. This decreased current reagent costs from +2.00 per test for the Syva manual method to 9 cents per test for our proposed method. Within-run and between-run CVs are typically less than 3% and 6%, respectively.
Paraproteinemia in patients with acquired immunodeficiency syndrome (AIDS) or lymphadenopathy syndrome (LAS).
Authors: Heriot K , Hallquist A E , Tomar R H 
Published: January 2020

Abstract
Eight of 15 patients with acquired immunodeficiency syndrome (AIDS) and six of nine patients with lymphadenopathy syndrome (LAS) had paraproteins in their sera. Twelve of these 14 were IgG kappa; the other two had no demonstrable light chains. The relationship of the paraprotein to the pathogenesis of AIDS is not clear, but we discuss its relation to derangements of B-cell immune regulation and function and to B-cell tumors in AIDS patients.
Radioimmunoassays for type III procollagen amino-terminal peptides in humans.
Authors: Niemelä O 
Published: January 2020

Abstract
Use of radioimmunoassay for the amino-terminal propeptide of type III procollagen for monitoring fibrotic processes in humans has been frustrating because of the nonparallel relation between results for the standard bovine antigen and human serum samples. In the radioimmunoassays I developed for this propeptide and its monomeric Col 1 domain, based on use of antigens from humans, serum samples generated less-steep inhibition curves than did the standard antigen in the propeptide assay; in the Col 1 assay, however, serum and urine samples both generated inhibition curves having the same slope as that generated with the standard Col 1 peptide. Concentrations of human fragment Col 1 in serum samples as measured with the Col 1 assay were usually double those obtained with the human propeptide assay, which in turn were two- to threefold those obtained with the bovine antigen assay. In control subjects and alcoholic cirrhotics the concentrations of antigen in urine and the daily excretion rates as measured with the assay for human Col 1 exceeded those reported previously. The presence of different antigen forms was demonstrated with both assays by gel-filtration analysis of serum and urine samples. The assay for human Col 1 should be suitable for routine clinical chemical use.
An anion-exchange chromatographic method for measuring bilirubin covalently bound to albumin.
Authors: Seligson D , Seligson H , Wu T W 
Published: January 2020

Abstract
After alkalinizing the diazo products of serum bilirubins, we apply them to a column of anion-exchange resin. The azodipyrroles derived from unconjugated and sugar-conjugated bilirubins, as well as from one half of the tetrapyrrole covalently linked to albumin ("Bil-Alb"), are anionic and protein-free and adsorb to the resin. The other half of the azo product of Bil-Alb, with absorptivity similar to that of the protein-free azodipyrroles, remains attached to albumin (Clin Chem 28:629-637, 1982) and passes through the resin unadsorbed. The color of the eluate correlates directly with the original amount of Bil-Alb present. Estimates of authentic Bil-Alb by the method agree with those by a Jendrassik-Gróf total-bilirubin method (in mg/L: intercept = -0.8, slope = 1.005, r = 0.999) and by liquid chromatography (Clin Chem 29:800-805, 1983) (n = 52, intercept = 5.2, slope = 0.724, r = 0.965). The CV of the method for serum with Bil-Alb of 99.4 mg/L was 3.8% (n = 8).
Can potentially infectious specimens containing hepatitis B virus be identified on the basis of their biochemical profile?
Authors: Burnett L , Lowe S B , Chan B , Whitfield J B , Nightingale B N , Hensley W J 
Published: January 2020

Abstract
The potential infectivity of 1129 randomly selected plasma specimens was directly assayed by hepatitis B virus (HBV) DNA dot-hybridization. Presence or absence of HBV was then correlated with a biochemical profile of 20 common analytes obtained on these same specimens. We found that potentially infectious specimens could not be identified on the basis of any combination of simple biochemical tests; indeed, the infectious specimens were more "normal" in some tests of liver function than were the non-infectious specimens.
Specific immunoassay of alpha-amylase isoenzymes in human serum.
Authors: Gerber M , Naujoks K , Lenz H , Gerhardt W , Wulff K 
Published: January 2020

Abstract
A monoclonal antibody (66C7) was prepared that specifically binds human salivary amylase (EC 3.2.1.1); it cross reacts with human pancreatic amylase by less than 1%. Two procedures are described for determination of isoamylases in human serum with this antibody: an enzyme immunoassay for determining amylase of salivary origin, and a routine method in which this amylase is immunoprecipitated and the remaining (pancreatic) amylase activity is assayed. Results by the two methods correlate well.
Three turbidimetric methods for determining total protein compared.
Authors: Nishi H H , Elin R J 
Published: January 2020

Abstract
We used human serum protein fractions to evaluate the sensitivity and bias of three turbidimetric methods for determining concentrations of proteins. Each fraction (Cohn Fractions II, III, IV, and V) was assigned a protein concentration value that was determined by the biuret method, which we calibrated with purified monomer of human serum albumin. All three turbidimetric methods (those involving sulfosalicylic acid/sodium sulfate, trichloroacetic acid, and alkaline benzethonium chloride) gave acceptable results for Fraction V with crystallized human serum albumin as the reference material, but there was bias by each of the three methods for the three globulin fractions. The method involving alkaline benzethonium chloride with measurement at 450 nm had the best sensitivity within the range of linearity and the most consistent bias among the three globulin fractions. These results define the dilemma for valid calibration of these methods for total serum protein in cerebrospinal fluid and urine.
Glucose transport in erythrocytes of diabetic and healthy children as related to hemoglobin A1c.
Authors: Mortensen H B , Brahm J 
Published: January 2020

Abstract
We studied glucose transport under physiological conditions (38 degrees C, pH 7.2, 5 mmol of glucose per liter) in erythrocytes of nine diabetic children with hemoglobin A1c values ranging from 6.6 to 13.8%, and in erythrocytes from six healthy children. Glucose transport was determined to be 2.38 (SD 0.16) X 10(-10) mol/cm2 X s (n = 18), and 2.47 (SD 0.18) X 10(-10) mol/cm2 X s (n = 12) in erythrocytes from diabetics and controls, respectively. The corresponding values for hemoglobin A1c were 11.0% (SD 2.3%) for the diabetics and 5.6% (SD 0.3%) for the controls. Thus the concentration of hemoglobin A1c, which reflects the degree of glycation of membrane proteins, differs significantly (p less than 0.001) between the two groups, whereas there was no significant variation (p greater than 0.1) in D-glucose transport. We conclude that glycation of the integral membrane protein that mediates glucose transport has no effect on transport function under physiological conditions.
Macro creatine kinase type 1 with electrophoretic mobility identical to that of the MB isoenzyme.
Authors: Medeiros L J , Greco F A , Walsh D , Gerson B 
Published: January 2020

Abstract
We describe the case of an elderly woman whose symptoms and electrocardiographic pattern initially suggested acute myocardial infarction. The value for total serum creatine kinase (EC 2.7.3.2; CK) was 737 U/L (reference interval: 22-269 U/L), and electrophoresis for CK isoenzymes demonstrated two bands, the more anodal migrating to the CK-MB region and the second migrating between the CK-MB and CK-MM regions. The above-normal total CK and electrophoretic pattern persisted during her 11-day hospital course. The QuiCK-MB (International Immunoassay Labs.) and Tandem-E CK-MB (Hybritech) immunoassays, however, showed CK-MB mass measurements within the normal range. In further investigation with a mixture of patient's serum and human-serum-based control containing all CK isoenzymes, the electrophoretic mobility of only CK-BB was altered, proving that the patient had antibody to the B unit of CK in her serum. Immunofixation revealed the more anodal band to be a CK-IgA lambda complex, and the more cathodal band, a CK-IgG kappa complex. Mixing the patient's serum with polyclonal antibody specific for CK-B slowed the electrophoretic mobility of only the more anodal band. Polyclonal antibody specific for CK-M had no effect on either band. Evidently, this patient had two different types of macro CK type 1, both containing CK-BB. We conclude that macro CK type 1 can mimic CK-MB and be a source of confusion.
Electrophoresis of serum protein to detect alpha 1-antitrypsin deficiency: five illustrative cases.
Authors: Malfait R , Gorus F , Sevens C 
Published: January 2020

Abstract
We describe five cases of severe alpha 1-antitrypsin (AAT) deficiency to illustrate the importance of visual inspection of electrophoretic patterns of serum proteins. In four patients the diagnosis of AAT deficiency was clinically unsuspected; in the other patient, the electrophoretic pattern was the first clue to confirm the diagnosis. Densitometric scanning of these patterns invariably overestimated the concentration of alpha 1-globulin. By visually inspecting electrophoretic strips instead of relying on densitometry, clinical chemists can help detect AAT deficiency earlier.