bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluorescence topography in biology. III: Characteristic deviations of tryptophan fluorescence in sera of patients with gynecological tumors.
Authors: Leiner M J , Schaur R J , Desoye G , Wolfbeis O S
Published: January 2020

The near-ultraviolet region of the total fluorescence (excitation-emission matrix) of human serum reflects essentially the fluorescence of protein-bound tryptophan. We examined topographically the tryptophan fluorescence of human serum. In comparison with fluorescence topograms from sera of healthy donors, sera of patients with gynecological malignancies showed significantly different patterns of tryptophan fluorescence, the major deviations being at 325 and 365 nm. In healthy donors, the tryptophan fluorescence intensity at 365 nm, expressed as percent of the maximum fluorescence intensity (i.e., at 337 nm) varied little, but was markedly lower for sera from patients with malignancies. We found no clear correlation between the extent of the fluorescence deviations and the relative concentration of the protein fractions as determined by electrophoresis. Furthermore, we could rule out inflammation in tumor patients as an explanation for this effect.
Occurrence of normal circulating proalbumin in a hemophilic A patient after acute hepatitis related to the delta virus.
Authors: Fine J M , Allain J P , Rochu D , Marneux M
Published: January 2020

Circulating proalbumin in humans has been described in two distinct events: genetic variants of proalbumin related to mutations at the cleavage site, and normal proalbumin related to an abnormal cleaving enzyme system. We report a case of acquired proalbuminemia that appeared after an acute episode of hepatitis related to the delta agent, in a chronic carrier of hepatitis B virus. This component, not present in normal plasma, was identified as proalbumin by immunological methods. It was indistinguishable from the molecule normally present in hepatocytes as judged by electrophoretic mobility, limited susceptibility to tryptic digestion, and its inability to bind labeled Ni. We suggest that this release of proalbumin is related to the concurrent presence of both hepatitis B and delta virus in some of the infected hepatocytes.
Factors associated with microhematuria in asymptomatic young men.
Authors: Froom P , Gross M , Froom J , Caine Y , Margaliot S , Benbassat J
Published: January 2020

The prevalence of asymptomatic microhematuria (two to four or more erythrocytes per high-power field) in 1341 male Air Force personnel was 5.4%. The most powerful predictor of microhematuria (nearly 15-fold increased prevalence) was a history of recurrent microhematuria during the previous five years. Recurrent microscopic hematuria was present in 14.5% (8/55) of men with a history of urethritis, accounting for 26% (8/31) of the cases of recurrent microscopic hematuria. The prevalence of microhematuria was not affected by physical exercise, flight duty, or sexual intercourse during the 24 h preceding the urinalysis.
Choice of immunoglobulin G purification method in assays for antibodies to the thyrotropin receptor.
Authors: Brown R S , Kertiles L P , Kleinmann R E
Published: January 2020

Activity of autoantibodies to the thyrotropin receptor in the serum of patients with active Graves's disease was compared when the patients' IgG was purified by three different procedures: ammonium sulfate precipitation (I), a modified batch diethylaminoethyl cellulose method (II), and affinity chromatography on Protein A-Sepharose CL-4B (III). IgG extracted by I was significantly less potent in inhibiting binding of 125I-labeled thyroid membranes than that prepared by either II or III, and was significantly less effective than II in stimulating adenyl cyclase activity in thyroid membrane. Thyroglobulin, a serum protein whose concentration is increased in patients with various thyroid diseases, was coprecipitated in amounts sufficient to significantly inhibit binding only when method I was used, but not with either of the other two procedures. Evidently method I is inferior to either of the other two when used for purification of autoantibodies to the thyrotropin receptor. Method II used in this study, being faster and more economical than I and of equivalent efficacy, is a feasible alternative method for clinical use.
Increased creatine kinase MB in the absence of acute myocardial infarction.
Authors: Pierce G F , Jaffe A S
Published: January 2020

Although measurement of CK-MB is a very sensitive, specific, and cost-effective test for use in diagnosis or exclusion of acute myocardial infarction, it should not be used as the sole diagnostic indicator, and all positive values must be critically analyzed to exclude other causes of increased values in serum. This is particularly important when the population being tested consists of patients with multiple medical problems, with low to medium probability of myocardial infarction, and without clinical or other biochemical (i.e., LDH 1) evidence of acute myocardial infarction. When the temporal pattern and absolute CK-MB values are considered together with the patient's clinical status, the diagnostic specificity is dramatically increased. In addition, one must be familiar with the limitations of individual assay systems in order to exclude method-related artifactual values.
A simple radial immunodiffusion method for assay of beta 2-microglobulin in serum.
Authors: Wu J T , Clayton F , Myers S , Knight J
Published: January 2020

In this method for clinical measurement of beta 2-microglobulin, a 10 g/L agarose gel containing anti-beta 2-microglobulin is used, with subsequent staining with Coomassie Blue. Although the method is slow (requiring 30 h), it is inexpensive, reliable, and accurate over the range of 1 to 10 mg/L, and is useful in the determination of beta 2-microglobulin in serum and cerebrospinal fluid. A modified procedure in which staining with silver is used may be sufficiently sensitive for the clinical assay of urine.
Two-site enzyme immunoassay for alpha-fetoprotein in dried-blood samples collected on filter paper.
Authors: Tsao D , Hsiao K J , Wu J C , Chou C K , Lee S D
Published: January 2020

This is a method for measuring alpha-fetoprotein (AFP) in eluates of dried-blood samples on filter paper by use of a simple, sensitive two-site enzyme immunoassay. The spot, 6 mm in diameter (equivalent to about 12 microL of whole blood), is incubated overnight with alkaline phosphatase conjugated to rabbit anti-AFP antibody in a tube containing a polystyrene bead coated with mouse monoclonal antibody to AFP. After the beads are washed the enzyme activities associated with them are determined colorimetrically, with p-nitrophenyl phosphate as substrate. The measurable range of AFP is from 9 to 900 micrograms per liter of plasma. AFP in the dried-blood spot as determined by this method correlated well with the AFP value for serum from the same blood sample as determined by radioimmunoassay (r = 0.957, p less than 0.001). Preliminary studies in which we used this method with 242 healthy blood donors and 60 patients with hepatocellular carcinoma indicate that it may be suitable for use in mass screening for hepatocellular carcinoma in high-risk populations.
Analytical evaluation of four sensitive assays of thyrotropin, including effects of variations in patient sampling.
Authors: Kreutzer H J , Tertoolen J F , Thijssen J H , der Kinderen P J , Koppeschaar H P
Published: January 2020

Four immunometric kits for thyrotropin with detection limits below 0.1 milli-int. unit/L were evaluated with respect to accuracy, precision, specificity, matrix effects, and high-dose "hook" effect. We also studied variations of values related to the patients' sex and age and time of the day and season when samples were collected. Correlation among the four methods was excellent, except for a few samples, and the interference in these samples could be abolished by adding mouse serum or "suppression medium." These phenomena can also be expected to occur in other immunometric assays involving monoclonal antibodies. With some modifications all tests are suitable for a clinical study of the usefulness of the thyrotropin assay as a primary test for thyroid function.
Simultaneous quantification of erythrocyte zinc protoporphyrin and protoporphyrin IX by liquid chromatography.
Authors: Bailey G G , Needham L L
Published: January 2020

A simple, rapid, specific, and sensitive isocratic "high-performance" liquid-chromatographic procedure is described for measuring protoporphyrin (PPIX) and zinc protoporphyrin (ZPP) in erythrocytes. A 30-microL whole-blood sample is treated with a solution of formic acid, deproteinized with acetone, and centrifuged. A 20-microL aliquot of the supernate is injected into a system consisting of a stationary phase of mu-Bondapak C18 and a mobile phase of acetone, methanol, water, and formic acid. ZPP and PPIX are detected fluorometrically (lambda ex = 417 nm, lambda em = 635 nm) within 6 min. The range of linearity extends beyond 10 mg/L for ZPP and 580 micrograms/L for PPIX. The detection limits for ZPP and PPIX are 11.9 micrograms/L (6.93 pg) and 2.55 micrograms/L (1.485 pg), respectively. The precision for ZPP and PPIX determinations averaged 2.86 and 5.59%, respectively, for within-day CVs and 4.98 and 8.14, respectively, for among-day CVs. Analytical recoveries averaged 97.2% for ZPP and 101.5% for PPIX. Interferences in the form of fluorescent quenching of ZPP and PPIX by hemin are avoided by chromatographic separation. We also used this method to determine the purity of commercially prepared ZPP, and compared the results obtained with this method with those from an extraction method.
Pregnancy-specific beta 1-glycoprotein in serum in monoclonal gammopathies: relationship with serum beta 2-microglobulin, and cellular origin.
Authors: Fagnart O C , Tasiaux N , Masson P L
Published: January 2020

Pregnancy-specific beta 1-glycoprotein (SP1) was assayed by particle-counting immunoassay in serum from 86 healthy blood donors and 236 patients with various types of gammopathy. A concentration of 1 microgram/L was taken as the upper normal limit. Abnormally high values were found in one of 10 patients with monoclonal gammopathy of undetermined significance, in 65% of 152 patients with multiple myeloma, in 84% of 64 patients with Waldenström's macroglobulinemia, and in seven of 10 patients with monoclonal gammopathies associated with other myeloproliferative disorders. In a study of 90 myeloma patients, the SP1 value correlated (p less than 0.001) with the concentration of beta 2-microglobulin in serum, a value which had been corrected for possible renal dysfunction, but not with the concentration of the monoclonal component. SP1 was detected by direct immunofluorescence in myeloma cells of bone-marrow smears from six of 10 patients with myelomatosis. These six patients had serum SP1 values greater than 1 microgram/L, whereas the four patients with fluorescence-negative myeloma cells had SP1 values less than 1 microgram/L.
Radial-immunodiffusion assay of human apolipoprotein A-I with use of two monoclonal antibodies combined.
Authors: Marcovina S , Di Cola G , Catapano A L
Published: January 2020

We produced and characterized several monoclonal antibodies directed toward human plasma apolipoprotein A-I. Two of them, A-I-12 and A-I-57, individually precipitated purified or native high-density lipoprotein in agarose gel by double immunodiffusion. Because radial immunodiffusion performed with a single monoclonal antibody gave faint and diffuse rings of precipitation, we developed and optimized working conditions for using these two monoclonal antibodies combined to determine apolipoprotein A-I in human plasma. This combination gave easy-to-measure, clear, sharp rings, and linear and parallel standard curves for HDL3 (the primary standard) and a reference serum (the secondary standard). Moreover, no pretreatment of samples with dissociating agents or detergents is necessary. The assay was complete after overnight incubation, as compared with two to three days when polyclonal antisera were used. Apolipoprotein A-I concentrations as measured in 128 normolipidemic subjects and in 72 patients with various lipid disorders by the radial immunodiffusion technique with monoclonal antibodies (x) compared well (r = 0.882; y = 1.029x-0.036) with those measured by radial immunodiffusion with polyclonal antisera (y).
Improved fluorescence polarization assay for use in evaluating fetal lung maturity. II. Analytical evaluation and comparison with the lecithin/sphingomyelin ratio.
Authors: Foerder C A , Tait J F , Franklin R W , Ashwood E R
Published: January 2020

We assessed the analytical performance of an improved fluorescence polarization assay for use in evaluating fetal lung maturity and compared results with the lecithin/sphingomyelin ratio. During a three-month period 150 patients' samples were assayed by clinical laboratory personnel with both techniques. Values for the lecithin/sphingomyelin ratio correlate closely with net fluorescence polarization values (r = -0.85), less closely with net fluorescence intensity (r = 0.65). Background fluorescence intensity and polarization varied widely, indicating a need to correct measurements for endogenous fluorescence. Net fluorescence polarization values have a CV of 0.32% within-run, 1.07% between-day. A comparison of two amniotic fluid centrifugation procedures showed no significant difference in such values. For both methods, however, such values are slightly but significantly higher than those obtained for amniotic fluids without prior centrifugation. Short-term storage (less than 30 days) of uncentrifuged amniotic fluid samples at -20 degrees C does not significantly affect results.
Improved estimation of cholesteryl ester transfer/exchange activity in serum or plasma.
Authors: Groener J E , Pelton R W , Kostner G M
Published: January 2020

This simple, routine assay for measuring cholesteryl ester transfer/exchange activity in human plasma is based on the removal of interfering lipoproteins--very-low-density (VLDL) and low-density lipoproteins (LDL)--by precipitation with polyethylene glycol. High-density lipoproteins (HDL) in the samples do not affect the results. The supernate after precipitation is mixed with [14C]cholesteryl ester-labeled LDL as donor and with HDL as the acceptor for the cholesteryl ester. After incubation for 16 h at 37 degrees C, LDL is separated from HDL by precipitation with dextran sulfate and the radioactivity measured in the supernate, which contains the HDL. The assay is applicable to samples containing as much as 10 mmol of triglycerides per liter. The within-assay CV was 2.7%, the day-to-day CV 6.8%. Results compared well with those by conventional procedures.
Thrombin clotting activity measurement and standardization with lyophilized plasma.
Authors: Fenton J W , Wideman C S , Evatt B L
Published: January 2020

Thrombin-induced clotting times were inversely proportional to fibrinogen concentrations within the range of 98 to 2900 nmol/L; these reciprocal velocity measurements had units of seconds per clot. By analogy with classical enzyme kinetics, we defined rectangular hyperbolic parameters where Km(clot) ranged from 0.14 to 0.56 mumol/L and kclot from 0.020 to 0.075 clot per second. Specificity ratios (kclot/Km(clot)) showed that reconstituted lyophilized human plasma is as good, if not better, a source of clottable fibrinogen as the purified protein itself. These ratios also showed that the presence of greater than 98% of the autoproteolytic forms (beta- and gamma-thrombins) of the human enzyme did not interfere with clotting activity attributable to alpha-thrombin. Contrary to simple enzyme kinetics, velocities (reciprocal clotting times) were rectangular hyperbolically related to clotting activities. Clotting times between 5 and 90 s/clot correlated (r greater than 0.999) with reciprocal alpha-thrombin concentrations, permitting standardization with lyophilized plasma (1000 U.S. "NIH" thrombin-clotting units/L corresponded to approximately 21 s/clot with these plasma). Lyophilized plasma re-examined after 15 months displayed no change in clottability.
Derivative spectroscopic determination of paraquat in serum.
Authors: Kuo T L
Published: January 2020

A reliable and sensitive method is described for the quantitative determination of the herbicide paraquat in serum. It involves the formation of dodecyl sulfate-paraquat ion pairs, adsorption of these ion-pairs on XAD-2 resin, and determination of the sensitive derivative spectrum of reduced paraquat. Analytical recovery of paraquat added to serum was about 86% at concentrations of 0.02-1.0 mg/L. Assay sensitivity is 0.005 mg/L, but this could be increased two- to fivefold by using greater volumes (4-10 mL) of serum/plasma without encountering problems of turbidity. The proposed method also avoids interferences from severe jaundice, which generally occurs in patients with paraquat poisoning.
Change in concentrations of myogenic components of serum during 93 h of strenuous physical exercise.
Authors: Kosano H , Kinoshita T , Nagata N , Takatani O , Isobe M , Yazaki Y
Published: January 2020

Effects of 93 h of long, strenuous ranger training on activities of creatine kinase (CK) and lactate dehydrogenase (LD), along with their isoenzymes, and on concentration of myosin light chain were examined in sera of young soldiers. Total CK activity in serum was measured before, during, and after the training. Throughout, total CK activity in serum increased steadily. At the end of the training, activity of CK-MB was increased but its activity ratio to total CK remained unchanged; the activity ratio of LD1/LD2 also was not increased, although total LD activity was increased. Myosin light chain was increased by about fourfold at the end of the training and remained high for three days thereafter. However, its concentration was much lower than in myopathies such as polymyositis and Duchenne muscle dystrophy. The increased activities in serum of total CK and CK-MB isoenzyme on strenuous physical exercise evidently were of noncardiac origin. Although CK activity was comparable with that seen in myopathies accompanied by disintegration of skeletal muscle, the relatively low concentration of myosin light chain in serum suggests minimal skeletal muscle damage.
Prediction of fetal lung maturity by use of the Lumadex-FSI test.
Authors: Lockitch G , Wittmann B K , Snow B E , Campbell D J
Published: January 2020

We analyzed amniotic fluid from 91 pregnancies (estimated gestational age range 31 to 41 weeks), using the Lumadex-FSI Fetal Lung Maturity test (Beckman Instruments), and also determining phosphatidylglycerol content, the lecithin/sphingomyelin ratio, and foam stability index by the "shake test," and compared results with newborn outcome. Five of 64 babies born within 72 h of testing developed hyaline membrane disease. Except for the lecithin/sphingomyelin ratio, the predictive value of a negative test was 100% but that of a positive test was less than 50%. Use of all four tests did not offer diagnostic advantage over the use of Lumadex-FSI alone. For the laboratory that infrequently assesses fetal lung maturity, we believe the sealed cassette format of the Lumadex-FSI will permit better quality assurance than the shake test. The Lumadex-FSI test is intended to provide a graded estimate of positive risk for hyaline membrane disease, but more data from different centers and patient populations are needed to establish reliable predictive values.
Agarose electrophoresis and inhibitor tests for isoamylase determination can give complementary clinical information.
Authors: Gorus F , Deruyter L , De Waele B , Sevens C
Published: January 2020

We report the presence of an extremely high proportion of "aged" amylase in the serum and cyst fluid of a patient with a pancreatic pseudocyst. A salivary amylase inhibitor test helped us to differentiate these "aged" pancreatic amylases from salivary fractions having a similar electrophoretic mobility.
Degree of unsaturation of the fatty acid chains of phospholipids influences the fluorescence polarization: implications for evaluating fetal lung maturity.
Authors: Dohnal J C , Bowie L J , Burstein H J
Published: January 2020

To study the effect of fatty acid chain saturation on the fluorescence polarization assay as a measure of fetal lung maturity, we used purified phospholipids isolated from human amniotic fluid and various commercial phospholipids. We found that the fluorescence polarization value decreased as the concentration of unsaturated fatty acids increased. In contrast, the lecithin/sphingomyelin ratio increases with increasing amounts of saturated lecithin, produced as the fetal lung matures. Since only saturated lecithins are surface active, the two indices of fetal respiratory status must reflect different properties of lung surfactant.
Radioimmunoassay of atrial natriuretic peptides in human plasma.
Authors: Hartter E , Woloszczuk W , Stummvoll H K
Published: January 2020

The concentration of atrial natriuretic peptide (hANP) in plasma from venous blood of healthy subjects was measured by radioimmunoassay. hANP from 5 mL of EDTA-treated plasma was adsorbed onto Sep-Pak C18 cartridges, which were eluted with methanol/trifluoroacetic acid (5 mL/L), 90/10 by volume. The eluates were concentrated by evaporation under nitrogen and lyophilized. After redissolving the samples in 0.5 mL of sodium phosphate buffer, we incubated 100-microL aliquots with anti-alpha-hANP for 24 h, then added 125I-labeled alpha-hANP tracer; 24 h later, we separated the bound and free fraction by adding an antibody/polyethylene glycol complex as the second antibody. The sensitivity of the assay was 2 pg per tube (B0-3 SEM). In the useful range of B = 15 to 85% of B0, CVs for within-run and between-run precision did not exceed 8 and 12%, respectively. The 50% intercept of the standard curve was at 12 pg per tube. hANP concentrations for 36 healthy adults ranged from 8 to 68 ng/L.
Determination of tissue plasminogen activator and its "fast" inhibitor in plasma.
Authors: Chmielewska J , Wiman B
Published: January 2020

We describe efficient, accurate methods for specific determination of tissue plasminogen activator (t-PA, EC 3.4.21.31) and its "fast" inhibitor in plasma. In this coupled assay, a sample containing t-PA is incubated with plasminogen, a plasmin (EC 3.4.21.7) substrate of low Km and high Kcat, and fibrin as a stimulator. The inhibitor of t-PA is determined by incubating the sample with a known amount of t-PA in excess, then determining the residual t-PA. Both t-PA and t-PA inhibitor can be determined in many samples simultaneously within a few hours. These assays are modifications of procedures described by us (Clin Chim Acta 1983;127:279-88 and Thromb Res 1983;31:427-36). Their accuracy as assessed by analytical recovery of pure t-PA added to blood samples (91 +/- 4%) or of partly purified inhibitor added to plasma samples (102 +/- 10%) is satisfactory, as is their precision. For the t-PA assay the CV was 1.6% (within run) or 4.1% (between run). The corresponding values for the inhibitor assay were 4.5% (within run) or 8.4% (between run) if the inhibitor concentration exceeded 3 arb. units/mL.
Liquid-chromatographic detection of aspartylglycosaminuria.
Authors: Mononen T , Parviainen M , Penttilä I , Mononen I
Published: January 2020

We describe a specific, simple liquid-chromatographic method for detecting the lysosomal storage disease aspartylglycosaminuria. The method is based on identification and quantification of the major storage compound 2-acetamido-1-L-beta-aspartamido-1, 2-dideoxy-beta-D-glucose in the urine of affected individuals. Sample preparation and chromatographic analysis requires 30 min. Within-day variation of the method was less than 4.4%, between-day variation less than 11.7% (n = 10 each).
Dietary citric acid enhances absorption of aluminum in antacids.
Authors: Slanina P , Frech W , Ekström L G , Lööf L , Slorach S , Cedergren A
Published: January 2020

Ten healthy men ingested, twice daily between meals, during each of the seven-day experimental periods: (a) citric acid (as lemon juice), (b) Al(OH)3, or (c) Al(OH)3 + citric acid. Whole blood sampled after each dietary period was analyzed electrothermally after digestion with nitric acid. Moderate, but significant, increases in mean Al concentrations as compared with pretreatment values [5 (SD 3) micrograms of Al per liter] were seen after ingestion of either citric acid or Al(OH)3: 9 (SD 4) and 12 (SD 3) micrograms/L, respectively. Ingestion of both Al(OH)3 and citric acid resulted in a more pronounced, highly significant (p less than 0.001) increase in Al concentrations, to 23 (SD 2) micrograms Al/L, probably owing to formation and absorption of Al-citrate complexes.
Screening for thyroid disease in women greater than or equal to 50 years of age seeking hospital care: influence of common nonthyroidal illness on serum free thyroxin as determined by analog radioimmunoassay.
Authors: Nyström E , Petersen K , Lindstedt G , Lundberg P A
Published: January 2020

We determined free thyroxin (fT4; analog radioimmunoassay) and thyrotropin in serum of women greater than or equal to 50 years of age who were attending a medical casualty ward (n = 363) or a medical outpatient clinic (n = 496), in order to estimate the prevalence of low fT4 results associated with nonthyroidal illness and to screen for previously unknown thyroid disease. Individuals with results outside stated limits were followed up within two to four weeks. Only about 5% of the women seeking acute medical care showed a decrease in fT4 concentration in association with a normal thyrotropin concentration. As expected, this combination was even less common in outpatients. We found a prevalence of previously undiagnosed thyroid disease of clinical significance of 0.8% in medical acute-care cases, 1.8% in medical outpatients. For this clinical setting we regard the simple analog technique as acceptable in spite of the low values reported for some hospitalized patients with nonthyroidal illness.
New method ("SPAC ET") for free thyroxin in serum evaluated.
Authors: Plebani M , Perobelli L , Burlina A
Published: January 2020

We analytically and clinically evaluated a new commercial method ("SPAC ET") for simultaneously determining total and free thyroxin in serum. We found the method to be rapid, simple, and precise. Results significantly correlated with those by "symmetric" dialysis and also agreed with the clinical data for patients with extremely low or high concentrations of thyroxin-binding globulin. On contrast, in those patients the most commonly used thyroid indexes (free thyroxin index or thyroxin:thyroxin-binding globulin ratio) failed to correctly reflect the true functional status of the thyroid.
Immunoradiometric assay of thyrotropin as a "first-line" thyroid-function test in the routine laboratory.
Authors: Hopton M R , Harrop J S
Published: January 2020

We compared the utility of a sensitive immunoradiometric assay for serum thyrotropin as a "first-line" thyroid-function test with a strategy based on first measuring total thyroxin in serum. The immunoradiometric assay appears to distinguish primary hypothyroidism and hyperthyroidism from euthyroidism in "new" patients. The role of this test in monitoring antithyroid treatment or thyroxin-replacement therapy is not yet established, there being particular difficulty in interpreting low thyrotropin concentrations in such patients. Nevertheless, because a normal thyrotropin concentration in most, if not all, situations signifies the euthyroid state, thyrotropin determination by immunoradiometric assay merits consideration as an initial test by laboratories performing thyroid-function tests.
Direct determination of sulfate conjugates of 17-oxosteroids in urine by liquid chromatography.
Authors: Nishikaze O , Iwata J
Published: January 2020

We describe a new liquid-chromatographic method with fluorescence detection for direct simultaneous determination of four urinary sulfate conjugates of 17-oxosteroids (17OS), without use of solvolysis or enzymatic hydrolysis. The 17OS sulfates in urine samples are extracted with benzene as ion pairs in the presence of benzyltributylammonium chloride. These ion pairs are converted to hydrazones by use of dansyl hydrazine in trichloroacetic acid solution and then are separated by liquid chromatography. The proposed method, being simple and rapid, shows a good separation of 17OS sulfates and superior sensitivity, sufficient recovery, and good reproducibility.
Radioimmunoassay of prolactin in blood spotted on filter paper.
Authors: Bassett F , Gross B A , Eastman C J
Published: January 2020

In this method for estimating prolactin, 50 microL of whole blood obtained by finger puncture is spotted onto filter paper and blood-spot samples are "punched out" with a 3-mm (diameter) paper punch. The blood is extracted with aqueous buffers and the prolactin measured in large batches by radioimmunoassay. Results were identical with those for prolactin in serum. Prolactin in blood spots is stable at room temperature for up to one week and for several months at -20 degrees C. This simple technique for obtaining blood samples for prolactin estimation has particular potential for field studies of lactating women.
Densitometry and microchromatography compared for determination of the hemoglobin C and A2 proportions in hemoglobin C and hemoglobin SC disease and in hemoglobin C trait.
Authors: Krauss J S , Drew P A , Jonah M H , Trinh M , Shell S , Black L , Baisden C R
Published: January 2020

Using both densitometry and anion-exchange microchromatography, we measured hemoglobin C (Hb C) and Hb A2 proportions in 11 patients, eight of whom had Hb AC, two Hb SC, and one Hb CC. For one patient with Hb SC, we made the determinations before and after a transfusion. The mean (and SD) for the sum of Hb C + Hb A2 by densitometry and anion-exchange microchromatography for the nine patients with Hb AC and Hb CC were 45 (18) and 40 (18)%, respectively (p greater than 0.1, r = 0.98); for the three determinations involving the two Hb SC patients, the respective proportions were 40 (9.9) and 38 (6.6)% (r = 0.88). Electrophoretic analysis of microchromatographic eluates from the Hb AC and Hb CC patients showed that 6% of the absorbance of the late high-ionic-strength eluate was due to Hb C, which was responsible for the statistically insignificant difference between densitometric and chromatographic values for Hb C + A2 values. Electrophoresis on cellulose acetate of concentrated eluates of the Hb C + A2 fraction from the two Hb SC patients revealed no contamination by Hb S. Evidently, microchromatography can be used to determine Hb C + A2 in patients with Hb C or Hb SC disease or Hb C trait.
Ascorbate in plasma as measured by liquid chromatography and by dichlorophenolindophenol colorimetry.
Authors: VanderJagt D J , Garry P J , Hunt W C
Published: January 2020

Ascorbic acid was measured in 125 plasma samples by an automated colorimetric method involving dichlorophenolindophenol and by a "high-performance" liquid-chromatographic procedure with electrochemical detection. The two methods gave comparable results for samples with ascorbate concentrations of 1 to 20 mg/L (r = 0.97). We also measured the amount of total ascorbate (ascorbic acid + dehydroascorbic acid) in the same samples by a liquid-chromatographic procedure with precolumn derivitization of ascorbic acid. We confirmed that plasma contains little dehydroascorbic acid.
Simplified liquid-chromatographic determination of vancomycin.
Authors: Rosenthal A F , Sarfati I , A'Zary E
Published: January 2020

We simplified determination of vancomycin in serum by using a direct and rapid solvent precipitation of protein and by using a simple organic compound as internal standard. Reproductibility of the vancomycin retention time was improved by modifying the mobile phase. Data obtained by fluorescence polarization immunoassay correlated well, and there was little bias between the two methods. The present method is sufficiently rapid to make this a practical choice for many laboratories.
Liquid-chromatographic determination of hemoglobin A2.
Authors: Turpeinen U
Published: January 2020

In this liquid-chromatographic assay for hemoglobin A2 (Hb A2) in human blood, the blood samples are hemolyzed by dilution and the hemolysates are chromatographed on a weak cation-exchanger with a solvent gradient of a buffer with two different ionic strengths. The absorbance of the effluent is monitored at 405 nm. The retention time of Hb A2 is less than 10 min. The mean within-assay CV was 1.6%, the between-assay CV 4.9%. I describe the effects of various column dimensions and sample preparation methods on the separation of Hb A2. The normal reference interval (for 54 healthy adults) was 1.3 to 3.0%. A comparison between results by a minicolumn method and by the present method is performed. Rapid and reproducible, this method is suitable for use in routine determination of Hb A2.
Simplified methods for measuring cholesterol concentrations of high-density lipoprotein subclasses in serum compared.
Authors: Whitaker C F , Srinivasan S R , Berenson G S
Published: January 2020

We used a combination of heparin micro-affinity column chromatography and heparin-Mn2+/dextran sulfate (DS) precipitation procedures to measure directly the total high-density lipoprotein (HDL)-cholesterol and HDL3-cholesterol in serum. The value for HDL2-cholesterol was obtained by subtracting the value for HDL3-cholesterol from that for total HDL-cholesterol. Results of this methodology and of the original heparin-Mn2+/DS double-precipitation method were compared with those of preparative ultracentrifugation. Concentrations of HDL- and HDL2-cholesterol by the original double-precipitation method were respectively 26 and 33 mg/L lower than by the ultracentrifugation method (p less than 0.001). Corresponding values by the micro-affinity/precipitation method were 36 and 29 mg/L higher than by the ultracentrifugation method (p less than 0.001). The values for HDL3-cholesterol by ultracentrifugation and by precipitation differed only by 7 mg/L (p greater than 0.05). Micro-affinity/precipitation and double-precipitation results both correlated well with those by ultracentrifugation (r = 0.84 to 0.94); the y-intercept of the comparison with the micro-affinity/precipitation method was close to zero. Use of the micro-affinity/precipitation method with samples from black or white adolescents showed that the blacks had higher concentrations of HDL2-(p less than 0.01) and HDL3-cholesterol (p less than 0.02) than did the whites.
Lactate dehydrogenase inhibition by immunoglobulin G in human serum.
Authors: Maekawa M , Sudo K , Iwahara K , Kanno T
Published: January 2020

Low lactate dehydrogenase (LD; EC 1.1.1.27) activity and an abnormal LD pattern in electrophoretograms of LD isoenzymes in the sera of two patients were caused by inhibition of LD by immunoglobulin G. One of these showed inhibitor activity in the serum upon direct analysis, while the other showed activity only after the immunoglobulin was stripped from the LD. As judged from the LD isoenzyme patterns in serum, the LD inhibitor appeared to act against M subunits. However, quantification of binding affinities to each isolated isoenzyme showed that the LD inhibitor had a stronger effect on LD isoenzymes 2 and 3 (H3M1 and H2M2, respectively).
Gas-liquid chromatographic method for determining urinary estriol, with 6 alpha-hydroxyestriol as internal standard.
Authors: Lindgren K
Published: January 2020

I describe a chromatographic procedure for quantification of urinary estriol in late pregnancy, with 6 alpha-hydroxyestriol used as internal standard. The hydrolyzed sample is successively passed through a Bond Elut C18 column and a DEAE-Sephadex column. The estrogens are then completely resolved as silyl ethers on a packed gas-liquid chromatographic (GLC) column in isothermal mode. Analytical recoveries of conjugated estriol ranged between 96 and 102%. Between-day precision (CV) was 4.4% at a mean concentration of 85.1 mumol/L. Specificity was assessed by comparing results obtained with a capillary GLC column.
A control system for monitoring the performance of leukocyte strip tests.
Authors: Pendergrass J H , Skjold A C , Cattell J A , Stover L R
Published: January 2020

The control system described here is used to monitor the performance of urinary reagent-strip tests for leukocytes. The presence of leukocyte esterase in the urine is used as a marker for leukocytes in urine. The control system is based on sonicated leukocytes, isolated from whole blood. The esterase activity of this sonicate is determined by spectrophotometry with the N-tosyl-L-alanine ester of 5-phenyl-3-hydroxypyrrole as substrate. The assay result is used to determine the amount of sonicate needed to prepare buffered esterase-containing solutions. Such control solutions mimic leukocytic urines and are stable for 6 h at room temperature. The variability of the control system was tested by preparing it five times in a day on five separate days. The overall CV for Leukostix Reagent Strips (Ames Division, Miles Laboratories, Inc.) when tested with these solutions and analyzed with a reflectance spectrophotometer was 8%; for visual readings it was 10%. The overall CV for Chemstrip LN Reagent Strips (Biodynamics, Indianapolis, IN) was 10%.
Sensitivity of isoelectric focusing, ion exchange, and affinity chromatography to labile glycated hemoglobin.
Authors: Mullins R E , Austin G E
Published: January 2020

We examined the effect of labile glycated hemoglobin on measurements of glycated hemoglobin by several commercial procedures. Erythrocytes from diabetic and nondiabetic patients were incubated in vitro with various concentrations of glucose, to generate labile glycated hemoglobin, and the species of glycated and nonglycated hemoglobin in each sample were identified by isoelectric focusing. Glycated hemoglobin was then assayed by the Bio-Rad A1 column method (I), the Bio-Rad A1c column method (II), and the Pierce affinity column method (III). I was sensitive to the labile (aldimine) fraction of glycated hemoglobin, and percentages of glycated hemoglobin so determined represented the sum of the labile fraction plus hemoglobin A1c and other stable glycated species. This spurious increase in glycated hemoglobin concentration by the aldimine could be obviated by any of three wash procedures, which eliminated the labile fraction from the samples: incubating the erythrocytes (a) in phosphate-buffered saline (pH 7.4) for 18 h at 22 degrees C, (b) in 100 mmol/L citrate (pH 5.0) for 30 min at 37 degrees C, or (c) in saline containing, per liter, 30 mmol of semicarbazide and 12 mmol of aniline hydrochloride (pH 5.0) for 30 min at 37 degrees C. Methods II and III did not detect the labile fraction. However, treatments a-c decreased the concentrations of stable glycated hemoglobin as determined by all three column-chromatographic methods as compared with unwashed sample. By isoelectric focusing we determined that blood with high glucose content had concentrations of aldimine roughly proportional to the blood glucose concentration. The kinetics of formation of labile glycated hemoglobin in these cells were consistent with the reported rate constants determined by using purified hemoglobin preparations in vitro.
Fluorometry of nanogram amounts of selenium in biological samples.
Authors: Tamari Y , Ohmori S , Hiraki K
Published: January 2020

For fluorometry of selenium in human blood, hair, and liver and in leaves, we wet-ashed the samples with conventional nitric and perchloric acids, and then extracted piazselenol (complex of Se and 2,3-diaminonaphthalene) in cyclohexane. Selenium was back-extracted from the cyclohexane into nitric acid to remove the fluorometric interferences of trace amounts of organic compounds. This fluorometric method is rapid and suitable for routine analysis. We applied the method to human hair samples and compared it with the data for non-destructive neutron activation analysis of the hair.
Is succinyldicholine the substrate of choice for the measurement of cholinesterase activity?
Authors: Faye S , Evans R T
Published: January 2020

We have developed a succinyldicholine-based assay for serum cholinesterase (EC 3.1.1.8) to help establish whether patients with suspected sensitivity to drugs of this type have enzyme abnormalities that cannot be detected by conventional laboratory techniques. Although the method discriminates between cholinesterase activities of drug-sensitive and nonsensitive people as well as an assay involving propionylthiocholine does, it has not revealed cholinesterase abnormalities in patients who experienced prolonged apnea after succinyldicholine, in whom no enzyme defect could be demonstrated by other procedures. Of 50 individuals who were apneic for between 20 and 180 min, only one had a cholinesterase activity less than the mean for E1u homozygotes by more than 2.5 SD. We conclude that the number of patients who experience clinical problems due to enzyme abnormalities that at present go unrecognized is small. Consequently, although succinyldicholine might eventually become the substrate of choice for cholinesterase, its advantages over propionylthiocholine are not yet sufficient to encourage its use.
Evaluation of an enzyme immunoassay kit for estrogen receptor measurements.
Authors: Raam S , Vrabel D M
Published: January 2020

Using an enzyme immunoassay (EIA) procedure, we evaluated the ability of the glass beads in the ER-EIA kit of Abbott Laboratories, which were coated with monoclonal anti-estrogen receptor (ER) antibodies, to bind hormone-free and hormone-filled Type I ER in cytosols, buffer washes, and 0.4 mol/L KCI extracts of ultracentrifugal pellets of breast cancer tissue homogenates. The unmodified ER-EIA technique yields higher values than does the dextran-coated charcoal (DCC) method for Type I ER. However, the antibody-coated beads fail to bind hormone-free ER and react with only a certain proportion of ER-[3H]estradiol complexes. The antigen saturation limit of the beads could not be determined because the quantity of antigen bound by the beads was disproportionate and unrelated to the total amount of the antigen available in the cytosols. In buffer extracts of tissue pellets that were ER-negative by the DCC assay, the EIA method detected high quantities of ER. We recommend checking the ability of the monoclonal antibodies to recognize proteins other than Type I ER in the extra-nuclear and nuclear compartments of target cells before using them for immunohistochemical detection of ER.
How to make laboratory information more informative.
Authors: Politser P E
Published: January 2020

I review psychological literature relevant to the design of medical laboratory data reports and computer display systems, illustrate how to improve such systems, and discuss needs for further research.
Interlaboratory standardization of enzyme results: the Richmond project.
Authors: Miller W G , Crane P D , Cryer C
Published: January 2020

Three concentrations of proficiency monitoring material and two concentrations of secondary standard calibrating material were prepared and stored frozen. The materials were prepared in buffer containing amylase from human saliva, aspartate aminotransferase from human liver, creatine kinase from human muscle, human serum albumin (20 g/L), and cofactors. The proficiency monitoring material was assayed by 10 methods in nine laboratories for 15 days to establish baseline performance. Each laboratory then used the secondary standard calibrating material to calibrate their instruments' responses to that of a standardization method, and repeated the assay of the proficiency monitoring material for 15 days. For amylase before calibration, between-laboratory mean values for the three concentrations of proficiency monitoring material were 29% lower than the standardization method, and the between-laboratory CV was 28%. After calibration the mean amylase values were 4% lower and the CV was 6%. For aspartate aminotransferase, the pre-calibration between-laboratory mean values were 24% higher than the standardization method (CV 14%) but only 3% higher (CV 6%) after calibration. CK activity deteriorated at storage temperatures above -70 degrees C. This study demonstrates that, by using a common secondary standard, laboratories can improve calibration of enzyme results.
Fluorometric assay for pancreatic lipase.
Authors: Salvayre R , Nègre A , Radom J , Douste-Blazy L
Published: January 2020

We report a new fluorometric assay in which a fluorescent triglyceride is used for determining lipase activity in serum, and we compare it with turbidimetric and radiometric methods. Because this fluorometric method is at least 50-fold more sensitive than the turbidimetric method, we have been able to develop a micromethod that requires only very small amounts of substrate reagent and serum. The use of fluorescent-labeled fatty acids allows direct determination of the product of lipase action and obviates the use of a standard for calibrating the method. Results of the fluorometric method are well correlated with those of the radiometric and turbidimetric methods, and the precision of the fluorometric assay is better than that of the turbidimetric method. Reference values for normal subjects are between 0 and 120 mU/L.
Determination of amylase activity in serum by using a wheat germ inhibitor with the Du Pont aca.
Authors: Lacher D A , Harize M B
Published: January 2020

A rapid procedure for determining salivary- and pancreatic-type amylase (EC 3.2.1.1) in serum by incorporating a wheat germ inhibitor (from Triticum aestivum) was developed for the Du Pont aca IV analyzer. Under optimal assay conditions, activities of salivary and pancreatic amylase were inhibited by 93% and 19%, respectively. The 95% central reference interval for the percentage of inhibition of serum amylase was 38-84%. Patients with acute pancreatitis showed less than 26% inhibition of amylase after addition of the wheat germ extract, reflecting the prevalence of pancreatic-type amylase in this disorder.
Warfarin administration increases uric acid concentrations in plasma.
Authors: Menon R K , Mikhailidis D P , Bell J L , Kernoff P B , Dandona P
Published: January 2020

The effect of warfarin administration on plasma uric acid was investigated. A representative sample of patients on long-term warfarin treatment had a significantly higher concentration of uric acid in plasma than did age-matched patients with comparable plasma urea concentrations who were not taking warfarin. In women, this association was observed only in patients with normal values for plasma urea, not in those with high values. In contrast, in men this association was present in both groups (normal and high plasma urea). In a longitudinal study involving patients, their plasma uric acid significantly increased after warfarin administration. There was no significant change in the renal clearance of uric acid after a single dose of warfarin in normal, healthy volunteers; this contrasts with the increase observed with other coumarin anticoagulants. Our findings suggest that the increase in plasma uric acid noted with warfarin administration is probably due to an increase in uric acid production and may predispose to gout those patients who are on long-term therapy with warfarin.