bluuebunny/crossref_metadata_2025 huggingface dataset:
Immobilized purified folate-binding protein: binding characteristics and use for quantifying folate in erythrocytes.
Authors: Hansen S I , Holm J , Nexø E
Published: January 2020

Purified folate-binding protein from cow's milk was immobilized on monodisperse polymer particles (Dynospheres) activated by rho-toluenesulfonyl chloride. Leakage from the spheres was less than 0.1%, and the binding properties were similar to those of the soluble protein with regard to dissociation, pH optimum for binding pteroylglutamic acid, and specificity for binding various folate derivatives. We used the immobilized folate-binding protein as binding protein in an isotope-dilution assay for quantifying folate in erythrocytes. The detection limit was 50 nmol/L and the CV over a six-month period was 2.3% (means = 1.25 mumol/L, n = 15). The reference interval, for folate measured in erythrocytes of 43 blood donors, was 0.4-1.5 mumol/L.
Concentrations of iodothyronines in serum of patients with chronic renal failure and other nonthyroidal illnesses: role of free fatty acids.
Authors: Liewendahl K , Tikanoja S , Mähönen H , Helenius T , Välimäki M , Tallgren L G
Published: January 2020

The mean concentration of free thyroxin (FT4) in serum, as determined by direct equilibrium dialysis, was decreased in patients with chronic renal failure (CRF) and increased in patients with various other nonthyroidal illnesses (NTI). The mean concentration of dialyzable free triiodothyronine (FT3) in serum was equally low in both groups of patients. Patients with CRF of various etiology but a similar degree of renal failure as estimated from serum creatinine assay had very similar concentrations of FT4 and FT3 in their serum. Mean thyroxin (T4) and triiodothyronine (T3) concentrations in serum were decreased in CRF and NTI, whereas the mean reverse-T3 concentration in serum was normal in CRF and increased in NTI. T4-binding globulin and albumin were markedly decreased in CRF and NTI; T4-binding prealbumin was increased in CRF and decreased in NTI. The mean concentration of nonesterified free fatty acids (FFA) in serum was increased in NTI but not in CRF. The weak, but significant, positive correlation observed between FT4 and FFA in serum (r = 0.34, P less than 0.01) in NTI indicates that the increase in serum FT4 in this group of patients could be an effect, at least in part, of FFA competing with T4 for binding sites on serum proteins. The stronger correlation detected between the serum FT4 concentration and the FFA/albumin molar ratio in serum (r = 0.60, P less than 0.001) demonstrates the importance of a low albumin concentration for expression of the effect of FFA on FT4 in severe systemic illnesses.
Biological variation of blood acid-base status: consequences for analytical goal-setting and interpretation of results.
Authors: Harding P J , Fraser C G
Published: January 2020

Analytical, intra-individual, and interindividual components of variation have been determined for pH, pCO2, bicarbonate, base excess, and total CO2 in capillary specimens of whole blood from a cohort of 14 healthy subjects. Calculated analytical goals (SD) are pH less than or equal to 0.008, pCO2 less than or equal to 0.9 mmHg, bicarbonate less than or equal to 0.5 mmol/L, base excess less than or equal to 0.5 mmol/L, and total CO2 less than or equal to 0.5 mmol/L. Because pH and base excess vary little between individuals, population-based reference values for them will be of utility in interpretation of results; pCO2, bicarbonate, and total CO2 show more marked variation between individuals, and reference values for them will be of more limited use. The generally applicable differences required for two results to be significantly different (P less than or equal to 0.05) when goals are met--which is currently feasible--are pH: 0.04, pCO2: 0.745 kPa (5.6 mmHg), bicarbonate: 2.6 mmol/L, base excess: 2.2 mmol/L, and total CO2: 2.7 mmol/L.
Thyroid function in hospitalized patients: effect of illness and serum albumin concentrations.
Authors: Desai R K , Jialal I , Aitchison J M , Joubert S M
Published: January 2020

We assessed the clinical utility of measuring thyrotropin (TSH) in serum by immunoradiometry and of measuring total thyroxin (TT4), total triiodothyronine (TT3), free thyroxin (FT4), and free triiodothyronine (FT3). We used a group of 110 healthy volunteers, 45 ill hypoalbuminemic patients, and 42 ill normoalbuminemic patients. In addition, the free thyroxin index (FTI) and TT4:thyroxin-binding globulin (TBG) ratio were also calculated. The hypoalbuminemic group had significantly lower FT4, FT3, TT4, TT3, and FTI concentrations, but only FT3 and TT3 were significantly lower in the ill normoalbuminemic group as compared with controls. We found significant correlation between FT4 and albumin (r = 0.372, P less than 0.001) and FT3 and albumin (r = 0.465, P less than 0.001). TSH concentrations were undetectable in two of 45 hypoalbuminemic patients, significantly higher in the rest. The TT4/TBG ratio was the only parameter of thyroid function that remained unchanged in the ill patients.
A New Method for Reporting the Sources of Abnormal Activities of Lactate Dehydrogenase in Serum
Authors: Politser Peter E , Powell Stephen H , Fink Jeffrey
Published: January 2020

Vol 32

p 1522: The unnumbered equation preceding equation 3 should read:

and equation 3 should read:

Vol 33

p225: The normal reference interval for albumin in urine should read 0.01 to 0.11 g per day.
A high-speed liquid-chromatographic method for measuring urinary porphyrins.
Authors: Johnson P M , Perkins S L , Kennedy S W
Published: January 2020

We describe a rapid quantitative and qualitative "high-performance" liquid-chromatographic (HPLC) method for measuring porphyrins in urine. Direct injection of acidified, filtered urine onto a 3-micron (particle size) 3-cm-long reversed-phase column fully resolves uroporphyrin, hepta-, hexa-, and pentacarboxylic acid porphyrins, and coproporphyrin. Instrument response is linearly related to concentration over the range 25 to 300 nmol/L. The method provides data essential for the differential diagnosis of porphyric states, including porphyria variegata and porphyria cutanea tarda. This relatively inexpensive method requires a run time of only 8 min per sample, making it particularly suitable for routine use in the clinical chemistry laboratory.
Ten commercial kits compared for assay of thyrotropin in the normal and thyrotoxic range.
Authors: Evans M C
Published: January 2020

I developed a standard procedure for assessing sensitivity, intra-assay precision, parallelism of sample dilutions, and assay drift, using a single trial assay kit. I used this to compare the performance of 10 commercial kits with an in-house radioimmunoassay for human thyrotropin. No one kit stood out as clearly superior overall. Differences in calibration between kits were evident in a comparison of thyrotropin concentrations measured in clinical samples, and by direct comparison of standards from different kits in a single assay. However, all kits gave clinically consistent results with respect to their published normal reference interval. Moreover, the performance of human thyrotropin assay kits has improved during the 14 months of this study.
Isolation of the acidic phospholipid phosphatidylglycerol from pulmonary surfactant by sorbent extraction chromatography.
Authors: Egberts J , Bulskool R
Published: January 2020

Aminopropyl solid-phase columns can be used for phospholipid fractionation. A method has been developed to elute the acidic phospholipid phosphatidylglycerol (PG) separately, and it is applicable to both standard (phospho)lipid mixtures and pulmonary surfactants. The simplicity, rapidity, and high recovery make this method of isolating PG superior to other chromatographic procedures.
An enzymatic method for 5-fluorocytosine.
Authors: Huang C M , Kroll M H , Ruddel M , Washburn R G , Bennett J E
Published: January 2020

We developed an enzymatic method for determination of 5-fluorocytosine in serum, using creatine iminohydrolase (EC 3.5.4.21), the Cobas-Bio analyzer, and an extant ammonia method. Analytical recovery (y) of drug added to serum (x) was good, with y = 0.97x-0.7, Sy.x = 3.6, r = 0.997 (n = 65) over the range 6.25 to 150 mg/L. Comparison with an HPLC method (x) showed good agreement: y = 0.98x + 1.34, Sy.x = 3.7 (n = 37), as analyzed with the Deming debiased regression. Precision was good, CVs being less than 3% for within-run and less than 6% for between-run controls. Ammonia, amphotericin B, glucose, urea, and hemolysis do not interfere, but bilirubin shows analyte-dependent interference and lipemia interferes when triglycerides exceed 5 g/L. This assay is accurate, inexpensive, and easy to perform. It can be easily adapted for routine or emergency use.
Variation in cytosolic protein expression between human colon tumors that differ with regard to differentiation class.
Authors: Nalty T J , Taylor C W , Yeoman L C
Published: January 2020

Using a combination of two-dimensional gel electrophoresis, silver staining, and a 16-quadrant grid system, we established a set of composite patterns for the colon tumor cytosol proteins of well, moderately, and poorly differentiated tumors. These composite patterns were found to be characteristic of the three individual differentiation classes for colon tumors. The apparent relative molecular masses (Mr) of the resolved proteins ranged from 14,000 to 105,000 and their isoelectric points from pH 5.2 to 8.4. Although the vast majority of the proteins identified in the composite patterns were common, a comparison based upon these patterns revealed two qualitative and seven quantitative protein differences. The qualitative differences were identified by apparent Mr X 10(-3)/pI coordinates of 73/7.2 and 66/6.2. Quantitative differences were identified by Mr X 10(-3)/pI coordinates of 71/6.0, 59/6.7, 57/6.7, 56/5.4, 52/6.1, 30/5.8, and 18/6.2. These cytosolic differentiation marker proteins may facilitate the diagnosis, staging, and monitoring of human colon cancer.
Monitoring hepatocellular carcinoma by using a monoclonal immunoenzymometric assay for alpha-fetoprotein.
Authors: Kelsten M L , Chan D W , Bruzek D J , Rock R C
Published: January 2020

A monoclonal immunoenzymometric assay for alpha-fetoprotein (M-AFP) was evaluated with respect to its utility in monitoring hepatocellular carcinoma (HCC) patients. Earlier (Clin Chem 1986;32:1318-22), we found this immunoassay to demonstrate abilities similar to polyclonal AFP assays, and we suggested that changes in M-AFP correlated with changes in intrahepatic tumor volume in most HCC patients. In the present study, 107 HCC patients were evaluated between 1978 and 1986. Patient demographics characterized this study population as being similar to those seen in regions with low incidence of HCC. Changes in serum M-AFP concentration correlated moderately (r = 0.55) with changes in intrahepatic tumor volume. The AFP concentration in serum was found to be a statistically significant independent predictor of survival; patients with above-normal M-AFP (AFP[+]) at presentation demonstrated a median survival time of 10 months, compared with 16 months for patients with "normal" values for M-AFP (AFP[-]) (P = 0.008). This prognostic pattern persisted when adjusted for serum bilirubin concentration (AFP[+] 12 months vs AFP[-] 29 months, P = 0.01).
Liquid-chromatographic profiling of solutes in serum of uremic patients undergoing hemodialysis and chronic ambulatory peritoneal dialysis (CAPD); high concentrations of pseudouridine in CAPD patients.
Authors: Schoots A C , Gerlag P G , Mulder A W , Peeters J A , Cramers C A
Published: January 2020

Using "high performance" liquid chromatography, we studied non-protein-bound fractions and total concentrations of 18 solutes accumulating in sera from a group of 12 patients who were undergoing chronic ambulatory peritoneal dialysis (CAPD) and in predialysis sera from a group of 15 hemodialysis (HD) patients. We monitored longitudinal changes in solute concentrations for two patients with respect to change of therapy between HD and CAPD. The concentrations of pseudouridine (P less than 0.001), uric acid (P less than 0.001), and an unknown fluorescent solute, "UKF3" (P less than 0.01), differed in sera of HD and CAPD patients. When standardized with respect to serum creatinine concentrations, the concentration of the transfer-RNA catabolite, pseudouridine, was significantly (P less than 0.0001) higher in sera of CAPD patients than in HD patients, suggesting an increase in turnover of transfer RNA. In stepwise linear discriminant analysis, the combination of pseudouridine and the probably biochemically related fluorescent unknown, UKF3, contributed most to the differentiation between sera from CAPD and HD patients.
Monitoring breast cancer with CA 549.
Authors: Chan D W , Beveridge R A , Bruzek D J , Damron D J , Bray K R , Gaur P K , Ettinger D S , Rock R C
Published: January 2020

CA 549, a new marker for breast cancer, was measured in serum of 719 patients by an immunoradiometric assay involving two monoclonal antibodies: BC4E 549, developed against a breast-tumor cell line, and BC4N 154, developed against milk fat-globule membrane. The reference interval for healthy women was 0-11 kilo-units/L. The percentages of patients with CA 549 greater than 11 kilo-units/L for benign conditions are: 0% pregnancy, 1% breast, 26% liver; and for nonbreast metastatic cancers: 12% endometrial, 33% lung, 40% prostatic, and 50% ovarian. In women with breast cancer who were receiving or had completed adjuvant therapy with no evidence of disease there was an 11% increase in CA 549. For patients with metastatic breast cancer, 19% of those in complete remission, 63% of those in partial remission, and 88% of those with systemic progression had increased CA 549. CA 549 is a more specific marker than carcinoembryonic antigen (CEA) in nonmalignant disease, nonbreast malignancies, and adjuvant breast-cancer patients, and it is more sensitive in breast-cancer patients with progressive disease than is CEA. We could show CA 549 to be superior to CEA for detecting active breast cancer in patients with malignant or nonmalignant breast diseases. In monitoring 19 adjuvant-treated patients, CA 549 correlated more closely with the clinical course than did CEA values and, when increased, predicted a clinical recurrence. In 18 breast-cancer patients with metastasis, monitored for two to three years, the change of CA 549 values paralleled disease courses more often than did CEA values.
Analytical bias for cholesterol and the percent of the population deemed at risk for coronary heart disease.
Authors: Kroll M H , Ruddel M , Elin R J
Published: January 2020

The effect of methodological bias on the population at risk is dependent on the location of the reference value in the distribution of the population. We fitted the cumulative distribution for cholesterol to a rational function and calculated the apparent reference values for four biased methods: Technicon SMAC (2.6%), DuPont aca (4.0 to 4.8%), Kodak DT-60 (-2.0 to -5.5%), and BMD Reflotron (-7.4 to -7.8%). With the true and apparent reference values for cholesterol and the rational function, we determined the percentage increase or decrease in the population deemed at risk for coronary heart disease. The population at risk increased by as much as 48% for methods with positive bias, and decreased by as much as 54% for methods with negative bias. If we restrict the percentage of the population incorrectly diagnosed to 3% and use reference values (cut points) recommended by the National Cholesterol Education Program, the maximum allowable methodological bias would be 1.6% for positive bias and -1.55% for negative bias. Therefore, an absolute methodological bias of 3% (as recommended by the Laboratory Standardization Panel) may be too liberal.
Efficacy of serum laminin measurement for diagnosis of fibrotic liver diseases.
Authors: Kropf J , Gressner A M , Negwer A
Published: January 2020

We examined the efficacy of laminin assay in serum for diagnosis of fibrotic liver diseases. Values for subjects with liver disease significantly (P less than 0.05) exceeded those for healthy subjects and patients with nonhepatic diseases. At a cutoff value of 1.45 kilo-units(arb.)/L (approximately 330 micrograms/L) and an assumed prevalence of fibrotic liver diseases of 0.5, positive and negative predictive values of the test were 0.97 and 0.83, respectively, for the comparison with a healthy reference population and 0.81 and 0.80 for nonhepatic diseased patients. Increases in laminin concentration were positively correlated with the extent of fibrotic transition of the liver. Discrimination between fibrotic and cirrhotic stages of chronic liver diseases by means of laminin assay was better than with the amino-terminal propeptide of type III procollagen. According to the criteria of diagnostic efficacy, we conclude that determination of laminin in serum improves the possibilities of clinical-chemical diagnosis of liver fibrosis and cirrhosis. However, as commonly true for other biochemical tests, determination of laminin cannot replace conventional diagnostic methods.
Nonspecificity of a direct 17 alpha-hydroxyprogesterone radioimmunoassay kit when used with samples from neonates.
Authors: Makela S K , Ellis G
Published: January 2020

We analyzed 240 samples for 17 alpha-hydroxyprogesterone (17-OHP) with the direct-assay kit ("Coat-A-Count" method for serum samples) from Diagnostic Products Corp. (DPC). The specimens were from 50 patients with known or suspected congenital adrenal hyperplasia (CAH); 74 mostly hospitalized neonates and infants, ages three days to three months; and 116 other patients, ages six months to 23 years. Samples from the CAH group were also analyzed with our in-house assay. For 39 of the neonatal samples, the analysis with the DPC assay was repeated with re-solubilized material that had been extracted from the serum with organic solvents. Values for "17-OHP" measured with the DPC direct assay were high, not only in CAH patients, but also in many of the unaffected neonates and infants. The extraction properties of the cross-reacting immunoreactive material into various organic solvent systems were different from those of 17-OHP, and were more like those of steroid sulfates. Because of this significant cross-reactivity, we recommend that the DPC kit not be used for sera from children younger than six months of age, unless the method is modified to include an extraction step.
Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique.
Authors: Tietz N W , Burlina A , Gerhardt W , Junge W , Malfertheiner P , Murai T , Otte M , Stein W , Gerber M , Klein G
Published: January 2020

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.
High-molecular-mass alkaline phosphatase: simplified and highly sensitive determination by liquid chromatography.
Authors: Schoenau E , Boeswald W , Herzog K H , Scheele J , Boehles H J , Stehr K
Published: January 2020

This simplified HPLC method for measurement of high-molecular-mass alkaline phosphatase (high-Mr AP; EC 3.1.3.1) in serum and bile is rapid (time for column preparation and separation 30 min), reproducible (CV 4.2%), and highly sensitive (detects high-Mr AP in healthy controls at 1-3% of total AP activity in serum), and is suitable for processing small batches of sample. We characterized high-Mr AP in serum and bile by incubating samples with L-phenylalanine, neuraminidase, 1-butanol, or wheat-germ lectin, and by determining stability to heat. High-Mr AP activity was determined in sera of patients with various liver diseases (4-32% of total AP serum activity) and results were compared with those by electrophoresis on agarose.
Extremely high values of prostate-specific antigen in patients with adenocarcinoma of the prostate; demonstration of the "hook effect".
Authors: Vaidya H C , Wolf B A , Garrett N , Catalona W J , Clayman R V , Nahm M H
Published: January 2020

We reviewed 721 consecutive samples submitted for measurement of prostate-specific antigen (PSA) over five months. We identified three patients with extremely high PSA concentrations: 650, 1840, and 3280 micrograms/L (their acid phosphatase activities were 3.2, 1337, and 2.8 U/L, respectively), and present case reports for the latter two. Serial dilutions of samples obtained from the patient with the highest PSA concentration indicated that the one-step Tandem-PSA assay gave falsely low values for high concentrations of PSA, an observation consistent with the phenomenon of the "hook effect." This effect was not observed when the sample was reanalyzed for PSA by a two-step procedure.
Abnormalities in thyroid function associated with chronic therapy with methadone.
Authors: English T N , Ruxton D , Eastman C J
Published: January 2020

We studied 145 clinically euthyroid patients on maintenance methadone therapy for narcotic withdrawal, to characterize abnormalities in thyroid-function tests induced by methadone. About a third had increased total thyroxin (T4) and total triiodothyronine (T3) concentrations in serum. The mean concentrations of T3, T4, and thyroxin-binding globulin (TBG) in serum were significantly greater (P less than 0.001 each) in these patients than in a euthyroid control group. There was a corresponding decrease in the T3 uptake (T3U) test, but the free thyroxin index (FTI) failed to correct for the increased TBG concentration in 15.9% of the patients. Individual and mean concentrations of free T3 (FT3) and free T4 (FT4) in serum and results of an "ultrasensitive" test for thyrotropin (TSH-IRMA) were within normal limits and confirmed the euthyroid state. We conclude that prolonged therapy with methadone causes increases in TBG, T3, and T4 in serum. FT3, FT4, and TSH-IRMA estimations are recommended as the diagnostic thyroid tests to use for patients on methadone maintenance therapy.
Use of creatine kinase MB isoenzyme for diagnosing myocardial infarction when total creatine kinase activity is high.
Authors: Thompson W G , Mahr R G , Yohannan W S , Pincus M R
Published: January 2020

The usefulness of measuring creatine kinase MB isoenzyme for diagnosing myocardial infarction when activities of total creatine kinase are very high is unclear. We conducted a retrospective study in an urban hospital that serves a largely indigent population. We concentrated on 146 patients whose creatine kinase activity was greater than 1000 U/L (upper limit of normal: 165 U/L for women and 225 U/L for men), with MB isoenzyme greater than 10 U/L and less than 5% of total creatine kinase. The positive predictive value of MB isoenzyme (isoimmune method) values greater than 10 U/L was between 11.6% and 56.8% when the value for total creatine kinase exceeded 1000 U/L. Using different values (MB greater than 4% of total creatine kinase) as positive for myocardial infarction would have resulted in far fewer false-positives, but 10 cases of myocardial infarction would have been missed. The most appropriate cutoff value for MB isoenzyme in this population (total creatine kinase greater than 1000 U/L) was found to be greater than 2% of total creatine kinase.
Activity of low-density lipoprotein receptors as estimated from concentrations of apolipoprotein B and C-II in serum.
Authors: Ito H , Naito C , Hayashi H , Kawamura M
Published: January 2020

The correlation between low-density lipoprotein (LDL) receptor activity and concentrations of lipids and apolipoproteins in serum was examined in 12 subjects with heterozygous familial hypercholesterolemia (FH) and in four with non-FH type II hyperlipoproteinemia. Concentrations of high-density lipoprotein cholesterol and of apolipoproteins (apo) A-I, C-II, and C-III were significantly positively correlated with LDL receptor activity, whereas LDL receptor activity was significantly inversely correlated with LDL cholesterol and apo B concentrations, and with apo ratios B/A-I and B/A-II. Neither total serum cholesterol, triglyceride, phospholipid, apo A-I, nor apo E concentrations correlated significantly with LDL receptor activity. Multiple regression analysis, with LDL receptor activity as the dependent variable, revealed concentrations of apo B and apo C-II to be the principal determinant factors. To confirm this, we subsequently calculated the LDL receptor activities before and after administration of CS-514, an inhibitor of hydroxymethylglutaryl-CoA reductase (EC 1.1.1.88), which increases the hepatic LDL receptor activity and decreases the concentration of cholesterol in serum. This drug increased calculated LDL receptor activities significantly, with a significant decrease in serum cholesterol.
Novel routine assay of thyroperoxidase autoantibodies.
Authors: Ruf J , Czarnocka B , Ferrand M , Doullais F , Carayon P
Published: January 2020

This radioimmunoassay was developed for specific and large-scale routine measurement of autoantibodies to thyroperoxidase (TPO), an enzyme recently identified as the thyroid microsomal antigen. Because of the scarcity of purified thyroperoxidase, we did not base the assay on the antigen-coated method but rather on autoantibody inhibition of the binding of labeled TPO to a solid-phase-bound monoclonal antibody to TPO. This assay design ensured highly specific measurements without interference from irrelevant thyroid antigens and autoantibodies. When we used affinity-purified autoantibodies to TPO as standards, the range of the curve extended over 10(3)-fold differences in the autoantibodies' concentrations, which allowed us to assay most sera without dilution. Within- and between-assay coefficients of variation (CVs) ranged from 6.1% to 11.5% and from 6.6% to 12.0%, respectively. The correlation between anti-TPO and antimicrosomal autoantibodies, as assessed by hemagglutination test, was highly significant (r = 0.90, P less than 0.0001). This assay is sensitive, easy to perform, and requires only trace amounts of purified TPO.
HPLC measurement of phenylalanine in plasma.
Authors: Atherton N D , Green A
Published: January 2020

Measurement of phenylalanine in plasma is required for the diagnosis and subsequent dietary management of phenylketonuria (PKU). We have developed an isocratic high-performance liquid-chromatographic (HPLC) method, with ultraviolet detection. For this measurement 10 microL of plasma is needed, and the complete analysis can be done in less than 15 min. Interbatch coefficients of variation for human plasma samples (phenylalanine 136-1541 mumol/L) ranged between 2.2% and 4.4%. The method has a wide linear range (10-3500 mumol/L), and results (y) correlated well with those (x) of an ion-exchange chromatographic method (r = 0.996; y = 1.014 x - 11.9; n = 64, range 22-1823 mumol/L). Only standard HPLC equipment is needed and no specialized sample preparation or detection system is required. The procedure has proved robust and reliable in regular routine use.
A longitudinal study of cholinesterase changes in pregnancy.
Authors: Evans R T , O'Callaghan J , Norman A
Published: January 2020

Serum cholinesterase activity was measured at intervals before, during, and after 44 pregnancies in 43 women. Three patterns of change were seen: (a) A decline in activity after conception, with no return towards pre-conception values before delivery (20 pregnancies). (b) A decline in activity accompanied by a partial or complete return to pre-conception values before delivery (19 pregnancies). (c) Either no discernible decline or increased activity during gestation (five pregnancies). We saw no association between these patterns and either the sex of the child, parity, smoking history, or alcohol intake. However, the continuous decrease in cholinesterase activity occurred in the youngest group of women, a decrease followed by an increase in the intermediate age group, and no decrease at all in the oldest group. Although not all the age-related differences quite reached statistical significance, these findings suggest that the patterns of change may be determined by some aspect of maternal physical maturity.
A new method for D-glucaric acid excretion measurement that is suitable for automated instruments.
Authors: Mocarelli P , Brambilla P , Colombo L , Marocchi A , Crespi C , Tramacere P , Mondonico A
Published: January 2020

Urinary excretion of D-glucaric acid (uGA) is an index of type II hepatic microsomal enzyme induction, indirectly revealing possible organic effects of some drugs and environmental pollutants. However, its determination is often cumbersome. We suggest a new, fast microanalytical method for uGA determination in which beta-glucuronidase (BG; EC 3.2.1.31) activity inhibition produced by uGA-derived 1,4-D-glucarolactone is measured. With use of purified BG, the method is suitable for centrifugal analyzers, allowing assay of greater than 100 samples per day. Moreover, the method measures uGA more accurately than other enzymatic methods based on BG inhibition. The within-day CV ranges from 7.9% to 4.6% (uGA 31.55-121.31 mumol/L); the between-day CV ranges from 11.5% to 5.0% (uGA 26.09-124.10 mumol/L). The detection limit is 6.0 mumol/L. The standard curve is linear from 10 to 200 mumol/L. Mean analytical recovery is 100%. Comparison with the method of Simmons et al. (Clin Chim Acta 1974;51:47-51) gave a correlation of r = 0.978, y = 1.40x-2.81. Reference intervals were established in a healthy population sample of 369 people (165 under 14 y), and uGA, expressed in micromoles per gram of creatinine, was higher in women than in girls or in males.
New enzymatic determination of sialic acid in serum.
Authors: Teshima S , Tamai K , Hayashi Y , Emi S
Published: January 2020

This enzymatic method for determination of sialic acid involves use of neuraminidase (EC 3.2.1.18), N-acetylneuraminate lyase (EC 4.1.3.3), acylglucosamine 2-epimerase (EC 5.1.3.8), N-acetylhexosamine oxidase (from Pseudomonas sp.), and peroxidase (EC 1.11.1.7). Because the method does not require pyruvic acid in the assay medium, interference by pyruvic acid in serum can be avoided. This simple, accurate assay is little affected by other substances in serum.
Immunoassay of alpha 1-acid glycoprotein in the Cobas Bio centrifugal analyzer.
Authors: Verme C N , Ludden T M , Harris S C
Published: January 2020

There is an increasing demand for quantification of serum alpha 1-acid glycoprotein (AAG, orosomucoid) in studies evaluating the protein binding of highly bound basic drugs. This paper describes an adaptation of an automated immunoturbidimetric assay for this protein to the Cobas Bio centrifugal analyzer. Replicate analyses of aliquots from six different solutions were used in determining precision. We also analyzed 367 patients' serum samples, in duplicate, to determine the distribution of AAG in hospitalized patients. The intra- and inter-run CVs ranged from 1.3% to 4.4% and from 0.6% to 6.6%, respectively. AAG concentrations in patients' samples ranged from 0.38 to 3.16 g/L. Results by this method correlate well with those by radial immunodiffusion, with no significant amount of bias between the two methods. This immunoturbidimetric procedure is faster and less expensive than currently used radial immunodiffusion techniques, and precision is acceptable.
An assay of uroporphyrinogen decarboxylase in erythrocytes.
Authors: McManus J , Blake D , Ratnaike S
Published: January 2020

Measurement of uroporphyrinogen decarboxylase (UROD; EC 4.1.1.37) activity in erythrocytes is useful in distinguishing between familial porphyria cutanea tarda (PCT), in which UROD activities are low, and acquired PCT, in which UROD activity is normal. In this method for measuring UROD, pentacarboxylic acid porphyrinogen I (PPI) is used as substrate. A sample of the patient's whole blood is incubated with PPI at 37 degrees C for 30 min at pH 6.0. The reaction is stopped by adding trichloroacetic acid/dimethyl sulfoxide containing mesoporphyrin (internal standard). The coproporphyrin so produced is measured directly by high-performance liquid chromatography, with fluorescence detection. Our values by this method for healthy subjects and non-PCT patients ranged from 1.8 to 4.0 U/L. The CV for the assay was 10% at 1.1 U/L and 9% at 2.4 U/L. Twelve of 42 patients with PCT had low erythrocyte UROD activities. In each of six families of patients with low UROD activity we found at least one other family member with a low UROD activity in erythrocytes.
Lactobacillus casei microbiological assay of folic acid derivatives in 96-well microtiter plates.
Authors: Horne D W , Patterson D
Published: January 2020

Microbiological assay is still widely used for estimating folic acid derivatives in serum and other biological samples. We describe here a modification of this procedure involving use of 96-well microtiter plates. This procedure, used with modern, computer-interfaced microtiter-plate readers and data-reduction software, greatly shortens the time and minimizes reagent costs for this assay. Under the conditions of our assay procedures, all folic acid derivatives tested gave equal growth response for Lactobacillus casei. Results for assays of rat liver extracts showed excellent agreement between the standard bioassay and the 96-well procedure.
Clinical Diagnosis of Mood Disorders
Authors: Rush A John
Published: January 2020

Vol 34:

p 813: In the fifth full paragraph in column 2, the second sentence should read "In 1934, von Meduna, a Hungarian psychiatrist..." (instead of 1983), and in the third sentence "1983" should read "1938." In the acknowledgements section to this paper, "MH-4115" should read "MH-41115."

p 1018: Add Richard A. Patrick to this list of authors' names.

p 1113: second column, 14th line from bottom, "32.1%" should read "10.9%" and, in the next line, "consistent" should read "inconsistent." Two lines further down, "60.7%" should read "18.5%" (see Letter by M. R. Hammer, in press).

p 1493: It is stated (column 2, third paragraph) that a DB-1701 column does not contain a nitrogen atom in its stationary phase. This is incorrect. The Phase is a 14% cyanopropylphenylsiloxane polymer.

p 1541: In the first full sentence in the right-hand column, "similarly higher" should read "similar."

p 1629: In the right-hand column, the second-to-last paragraph, the ninth line from the bottom should read "...0.5 mL of a reagent solution containing, per liter, 10 g of dextran sulfate (500 000 Da) and 0.5 mol of MgCL2"

p 1945: In line 6, column three, "0.65" should "0.965."

p 2148: Add I. Morales to this list of authors' names.
Quantification of lactate dehydrogenase-1 in serum with use of an M-subunit-specific monoclonal antibody.
Authors: Vaidya H C , Porter S E , Landt Y , Silva D P , Dietzler D N , Ladenson J H
Published: January 2020

We have developed a rapid, one-step assay for measuring lactate dehydrogenase-1 (LD-1) activity in serum after extraction of LD-2, LD-3, LD-4, and LD-5 isoenzymes by an immobilized M-subunit-specific monoclonal antibody (D.8.1). In the assay, 100 microL of serum is mixed with 50 microL of a suspension of 0.8-micron-diameter latex particles coated with 30 micrograms of the monoclonal antibody D.8.1, then incubated at room temperature for 5 min. The latex particles, to which LD-2 through LD-5 are bound, are pelleted by centrifugation for 2 min at 12,000 X g, and the LD-1 activity is measured kinetically in the supernatant fluid. We optimized the assay for antibody immobilization, antibody concentration, and time and temperature of incubation. Serum bilirubin concentrations up to 0.33 g/L (0.56 mmol/L) did not interfere in the assay. Hemolysis interfered solely through LD-1 released from erythrocytes. The within-assay CV for low-concentration quality-control material (LD-1 33 U/L) was 3.5% (n = 9) and for high-concentration material (LD-1 185 U/L) was 1.9% (n = 8); the between-assay CVs for the two materials were 6.1% (n = 9) and 2.5% (n = 10), respectively. The LD-1 activity measured in 98 samples by our assay compared well with a two-step polyclonal antibody-based assay (Isomune-LD, Roche Diagnostic Systems; r = 0.998) and with an electrophoretic method (Paragon, Beckman Instruments; r = 0.956).
Reference values for fructosamine concentrations in children's sera: influence of protein concentration, age, and sex.
Authors: De Schepper J , Derde M P , Goubert P , Gorus F
Published: January 2020

Fructosamine and protein (total and fractionated) were measured in the serum of 170 normal children, ages two weeks to 15 years. The mean fructosamine concentration was 2.12 mmol/L, 5% lower than the mean value observed for adults. We observed no sex-related difference in fructosamine values, but saw a pronounced age dependency of reference values. For children younger than three years, the mean concentration of fructosamine was 15% lower than in adults, but glycated protein concentrations increased with age, reaching essentially adult values by age six years. Expressing fructosamine concentrations per gram of serum total protein or of albumin weakened the influence of age, but did not eliminate it completely. We report reference intervals for fructosamine concentrations in children's sera.
Lactate dehydrogenase isoenzyme-1 in serum for detection of peri-operative myocardial infarction after cardiac surgery.
Authors: Rotenberg Z , Squires J E , Johnston M T , Hoyt J , Gibson R S , Bruns D E
Published: January 2020

We prospectively studied changes in serum lactate dehydrogenase isoenzyme-1 (LD-1, EC 1.1.1.27) in 99 consecutive patients after either coronary artery bypass grafting (CABG, n = 61), isolated cardiac-valve replacement (n = 24), or the two procedures combined (n = 14); 86 of these had no clinical evidence of peri-operative myocardial infarction (MI). Blood was sampled immediately after surgery and at 6-h intervals for up to 42 h thereafter. LD-1 was isolated by using the LD M-subunit antiserum. Samples from the non-MI patients were used to establish the reference intervals for LD-1. By 24 h after surgery, mean serum LD-1 values were higher (P less than 0.001) in non-MI patients who underwent isolated valve replacement (222 +/- 74 U/L) or combined CABG and valve replacement (266 +/- 58 U/L) than in 50 non-MI patients who underwent CABG alone (134 +/- 42 U/L). Separate reference intervals were determined for CABG and other patients at each sampling time. By 24 h after operation, LD-1 exceeded these reference intervals in the 10 CABG and two combined-procedure patients in whom other evidence of MI was present. Measurement of LD-1 24 to 42 h after cardiac surgery appears to be a useful test for the diagnosis of perioperative MI.
Error estimation in the quantification of alkaline phosphatase isoenzymes by selective inhibition methods.
Authors: Tillyer C R
Published: January 2020

A method for calculating, by selective inhibition, the activities in serum of isoenzymes of alkaline phosphatase (EC 3.1.3.1) originating from bone, liver, intestine, and placenta produced results for a sample of patients for which the imprecision was five- to 25-fold higher than that of the alkaline phosphatase method used--too imprecise for routine clinical use. Error analysis by direct calculation and by Monte Carlo estimation revealed that the algorithm used in the method completely accounted for the increase in imprecision of the isoenzyme estimations. I recommend that all methods involving such algorithms or the principle of multicomponent analysis should undergo a thorough error analysis by use of the techniques described here, to obtain an estimate of the increase in imprecision that is ascribable to the particular numerical technique used.
Activity of dipeptidyl peptidase IV and post-proline cleaving enzyme in sera from osteoporotic patients.
Authors: Gotoh H , Hagihara M , Nagatsu T , Iwata H , Miura T
Published: January 2020

The activity of dipeptidyl peptidase IV (EC 3.4.14.5) in human sera from normal controls and osteoporotic patients was assayed with Gly-Pro-4-methylcoumaryl-7-amide (Gly-Pro-MCA) as substrate, at pH 8.7. The mean normal value for the activity in serum of 120 healthy subjects (ages 20-86 y) was 54.0 (SE 0.9, range 34.3-81.6) U/L at 37 degrees C and differed slightly but significantly between the younger group (less than 50 y old) and those older than 50 y. Values for the younger men were slightly but significantly higher than for the older men. Overall, however, the enzyme activities in serum were above normal in patients with osteoporosis. In contrast, the activity of post-proline cleaving enzyme (PPCE) was not increased in serum from patients with osteoporosis, as determined with succinyl-Gly-Pro-4-methylcoumaryl-7-amide (Suc-Gly-Pro-MCA) as substrate. These results suggest that high activities of dipeptidyl peptidase IV in serum of patients with osteoporosis are probably related to its severity.
Improved rapid assay of uric acid in serum by liquid chromatography.
Authors: Tanaka M , Hama M
Published: January 2020

This improved method for rapid determination of uric acid in serum is based on high-performance liquid-gel-permeation chromatography, with hydrophilic and highly porous vinyl alcohol copolymer as packing material. It has the following advantages: no need for sample deproteinization or use of a precolumn, more than 500 serum samples can be analyzed without having to regenerate or recondition the analytical apparatus, and the analysis for uric acid is a one-step procedure. Correlation coefficients between this method and other methods are very good (r = 0.998, 0.999).
Secretion of creatine kinase MB isoenzyme by an immature teratoma with predominant rhabdomyosarcomatous elements.
Authors: Emancipator K , Kudelka A P , Bradford G , Leonard K A , Zarrabi M H
Published: January 2020

A 37-year-old man with metastatic immature (malignant) teratoma with prominent rhabdomyosarcomatous elements had markedly increased activity of creatine kinase (EC 2.7.3.2) MB in serum. There was no electrocardiographic evidence of infarction or ischemia, and autopsy revealed no myocardial infarction, significant coronary atherosclerosis, myocarditis, or invasion of the heart by tumor. A high proportion of the creatine kinase activity in a homogenate of the tumor was attributable to the MB isoenzyme. Persistent increases of creatine kinase-MB and an unusually high MB isoenzyme activity, out of proportion to total creatine kinase activity, may indicate a nonmyocardial origin of this isoenzyme.
Quantitative analysis for isoforms of creatine kinase MM in plasma by chromatofocusing, with on-line monitoring of enzyme activity.
Authors: Nohara R , Sobel B E , Jaffe A S , Abendschein D R
Published: January 2020

Changes in the proportions of individual isoforms of the MM isoenzyme of creatine kinase (CK; EC 2.7.3.2) in plasma promptly reflect both myocardial infarction and coronary recanalization. However, quantitative methods developed thus far are too slow or cumbersome for routine use in making clinical decisions. We report a convenient, quantitative chromatofocusing assay with on-line fluorometric detection of isoform activity in the column eluent that provides results within 40 min from the time of sample application. Sample eluted from a microbore chromatofocusing column (1.8-mL bed volume) is split between a reaction stream, into which CK reagents are added, and a reference stream. After incubation at 37 degrees C, NADPH formed by reaction of isoforms with CK reagent is detected at 340 nm. The system can detect activity of individual isoforms in plasma samples having total CK activity greater than or equal to 21 U/L (30 degrees C). Results correlated closely with those obtained by previously validated, but slow, chromatofocusing (r = 0.98, n = 30) and protein immunoblotting (r = 0.90, n = 20) procedures.
The gamma-glutamyltransferase isoenzyme pattern in serum as a signal discriminating between hepatobiliary diseases, including neoplasias.
Authors: Sacchetti L , Castaldo G , Salvatore F
Published: January 2020

We have used the gamma-glutamyltransferase (GGT) isoenzyme pattern in serum as a means for discriminating between hepatobiliary diseases, including neoplasias. The reference pattern, determined in 142 normal subjects with a simplified conventional cellulose acetate electrophoretic procedure, contained two GGT bands, alpha 1-GGT and alpha 2-GGT, in proportions of 60-80% and 20-40%, respectively. Sera from 95 hepatobiliary patients showed typical isoenzyme features: (a) a beta-migrating GGT form that was less than 10% of the total GGT in chronic hepatitis and cirrhosis, and less than or equal to 30% of the total GGT in cirrhosis with intrahepatic cholestasis and in cases of extra- and intrahepatic obstructive jaundice, including liver neoplasias; (b) a gamma-migrating GGT band and (or) a "dep-GGT" (nonmigrating) band in cases of extrahepatic jaundice; and (c) an albumin-migrating GGT band that had a diagnostic sensitivity of 75% for hepatic tumors. The diagnostic specificity of this last band is 92% toward other hepatic disorders and 91% toward nonhepatic neoplasias; we consider it a potential specific marker for primary or metastatic liver neoplasias.
Effect of iodination site on binding of radiolabeled ligand by insulin antibodies and insulin autoantibodies.
Authors: Diaz J L , Wilkin T J
Published: January 2020

Four human insulins and four porcine insulins, each monoiodinated to the same specific activity at one of the four tyrosine residues (A14, A19, B16, B26) and purified by reversed-phase liquid chromatography, were tested in a radiobinding assay against a panel of insulin-antibody (IA)-positive sera from 10 insulin-treated diabetics and insulin-autoantibody-positive (IAA) sera from 10 nondiabetics. Of the 10 IAA-positive sera, five were fully cross reactive with both insulin species, and five were specific for human insulin. The rank order of binding of sera with the four ligands from each species was random for IA (mean rank values of 1.9 for A14, 2.0 for A19, 2.5 for B16, and 3.6 for B26 from a possible ranking range of 1 to 4), but more consistent for non-human-insulin-specific IAA (mean rank values 1.3 for A14, 3.8 for A19, 1.7 for B16, and 3.2 for B26 for labeled human insulins; 1.2 for A14, 4.0 for A19, 1.8 for B16, and 3.0 for B26 for labeled porcine insulins). The rank order of binding was virtually uniform for human-insulin-specific IAA (mean values 1.2 for A14, 3.0 for A19, 1.8 for B16, and 4.0 for B26). The influence of iodination site on the binding of labeled insulin appears to be dependent on the proximity of the labeled tyrosine to the antibody binding site and the clonal diversity, or restriction, of insulin-binding antibodies in the test serum. When IA and IAA are measured, the implications of this study regarding the choice of assay ligand may be important.