bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzyme immunoassay of hemoglobin A1c: analytical characteristics and clinical performance for patients with diabetes mellitus, with and without uremia.
Authors: Engbaek F , Christensen S E , Jespersen B 
Published: January 2020

Abstract
We evaluated an enzyme immunoassay (Novo BioLabs) for determination of hemoglobin A1c and measured the contribution of carbamylated hemoglobin to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure. The reference interval, determined for blood donors, was 0.035-0.050 (i.e., 3.5% to 5% of the total hemoglobin). For non-diabetic patients with chronic renal failure, on hemodialysis, the mean proportion of hemoglobin A1c was 0.038 (SD 0.0045); for umbilical cord blood it was 0.006-0.009. For diabetic patients with normal or near-normal renal function, results by enzyme immunoassay (y) and HPLC (x) correlated well (r = 0.83): y = 0.99x - 0.005. Added fetal hemoglobin or carbamylated hemoglobin did not interfere with enzyme immunoassay, but added carbamylated hemoglobin co-chromatographed with hemoglobin A1c. Measurements for patients with chronic renal failure, with or without diabetes, by enzyme immunoassay and by HPLC, were compared with measurements for patients with diabetes mellitus but no renal failure. Carbamylated hemoglobin contributed 0.019 to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure.
Direct solid-phase enzymoimmunoassay of testosterone in saliva.
Authors: Howard K , Kane M , Madden A , Gosling J P , Fottrell P F 
Published: January 2020

Abstract
This competitive, solid-phase enzymoimmunoassay for testosterone in saliva is carried out on microtiter plates and involves no chromatographic or extraction steps. With an overnight incubation the detection limit of the assay is 230 fg per well (16.1 pmol/L). There was a good correlation (correlation coefficient 0.95) between testosterone concentrations measured with and without prior extraction of the saliva samples. Repeated assay of three control saliva samples containing a range of testosterone concentrations (200-1000 pmol/L) gave within- and between-assay coefficients of variation of 5.5-13.2%. The analytical procedure is simple and closely resembles already published procedures for the determination of progesterone and estrone (with extraction) in saliva. One person can assay 200 samples in 24 h and the assay is suitable for reproductive and sports medical applications, particularly for projects involving serial sampling and yielding large numbers of samples.
Monoclonal antibody to the gamma chain of human fetal hemoglobin used to develop an enzyme immunoassay.
Authors: Moscoso H , Shyamala M , Kiefer C R , Garver F A 
Published: January 2020

Abstract
A monoclonal antibody (mAb) that recognizes the gamma chain of human fetal hemoglobin (Hb F) has been produced by cell hybridization techniques. The mAb reacts with Hb F (alpha 2 gamma 2), Hb Bart's (gamma 4), and Hb Kenya (gamma-beta hybrid), but does not cross-react with Hb A (alpha 2 beta 2) or Hb A2 (alpha 2 delta 2). We describe a direct enzyme-linked immunoassay (ELISA) for measurement of Hb F, in which hemoglobins from standards or from unknown hemolysates are covalently bound to the wells of microtiter plates. The antigen is quantified by addition of the gamma-specific mAb, followed by anti-mouse IgG conjugated with horseradish peroxidase, and incubation with the substrate, tetramethylbenzidine. Absorbances at 630 nm are directly proportional to the amount of Hb F present in the standards or samples. Results for Hb F in 53 hemolysates agreed well with values obtained by "high-performance" liquid chromatography, RIA, alkali denaturation, and magnetic affinity immunoassay. This ELISA can detect a 0.5% proportion of Hb F in 1 h and offers distinct advantages over other techniques currently in use.
Mechanisms responsible for increasing immunoreactivity of apolipoprotein A-I with storage: the role of oxidation.
Authors: Wang X L , Dudman N P , Wang J , Wilcken D E 
Published: January 2020

Abstract
Atherogenesis has been linked to low concentrations of high-density lipoprotein and its principal carrier protein, apolipoprotein (apo) A-I, in serum. We measured apo A-I by enzyme-linked immunosorbent assay, using polyclonal antiserum raised against purified apo A-I and conjugated to peroxidase. During storage at 4 degrees C and above, the immunoreactivity of apo A-I increased so that measured values in stored serum were difficult to interpret. The immunoreactivity of serum apo A-I also increased substantially (up to 50-fold) during exposure to NaIO4. This increase was apo A-I concentration dependent, was linearly dependent on the concentration of NaIO4 up to 200 mmol/L at pH 7.4 and 25 degrees C, and was not ascribable to nonspecific binding of antibody-peroxidase conjugate to the reaction wells. Treatment with NaIO4 caused apo A-I immunoreactivity to increase to a peak or plateau, then gradually decline. In 100 mmol/L NaIO4 (pH 7.4, 25 degrees C), this plateau occurred 30-60 min after oxidation commenced. When frozen serum and stored nonfrozen serum were both oxidized with NaIO4 under the same conditions, the apo A-I from the frozen serum had a significantly (P = 0.0004) greater increase in immunoreactivity. Sera from different patients with different apo A-I concentrations did not have proportionately increased immunoreactivity after treatment with NaIO4. Our findings suggest that the increase in apo A-I immunoreactivity on storage at 4 degrees C or higher involves atmospheric oxidation, and they raise the possibility of in vivo oxidized and nonoxidized forms of apo A-I.
Antipyrine, indocyanine green, and lorazepam determined in plasma by high-pressure liquid chromatography.
Authors: Awni W M , Bakker L J 
Published: January 2020

Abstract
This HPLC method for measuring antipyrine, lorazepam, and indocyanine green in 0.5 mL of plasma can be used in studies of liver function in which these "model" compounds are used. After a fast, simple, one-step extraction procedure with acetonitrile, an isocratic HPLC system is used, with a single detection wavelength (214 nm) and a single internal standard (1-acetamidopyrene). The mobile phase is a 47/53 (by vol) mixture of acetonitrile and 50 mmol/L phosphate buffer, pH 6. The three compounds are separated on an LC-18 reversed-phase column. The low cost of the HPLC method makes feasible the routine clinical measurement of all three compounds.
Interaction between pyridine nucleotide coenzymes and heme proteins as a possible source of error in assay of activities of coenzyme-linked enzyme.
Authors: Jeyasingham M D , Pratt O E , Roopral H K 
Published: January 2020

Abstract
The ultraviolet absorbance spectra of pyridine nucleotide coenzymes change in the presence of heme-containing proteins. The positions of each of the two main absorbance peaks of NADH are shifted progressively towards shorter wavelengths in the presence of increasing concentrations of hemoglobin, and the third peak, at 220 nm, disappears altogether. Similar changes are seen in the spectra of NAD+ and NADPH, and similar effects on these spectra are produced by myoglobin and cytochrome c, but not by comparable concentrations of albumin. The spectral shifts are generally accompanied by a decreased peak height. This finding may help explain problems reported by previous workers in the measurement of the activity of enzymes such as transketolase or lactate dehydrogenase in erythrocyte hemolysates. Errors may be considerable if allowance is not made for this effect, especially if the concentration of heme protein in the spectrophotometer cuvette much exceeds 1 g/L. The interaction appears to indicate some form of bonding, occurring generally between pyridine nucleotide coenzymes and the heme group in proteins. We relate the findings to measurement of activities of pyridine nucleotide-linked enzymes in erythrocyte lysates and in plasma containing myoglobin after muscle breakdown.
Changes in concanavalin A-reactive proteins in inflammatory disorders.
Authors: Silvestrini B , Guglielmotti A , Saso L , Cheng C Y 
Published: January 2020

Abstract
Quantitative changes of concanavalin A (Con A)-reactive proteins in serum samples obtained from rats with induced inflammation and from patients with inflammatory and autoimmune diseases were examined by use of lectin blots. Treatment of rats with a single dose of fermented yeast to induce inflammation caused an extensive increase in Con A-reactivity. These changes were time dependent and were similar in both sexes of the animals. When we examined serum samples obtained from patients with various inflammatory disorders for their Con A-reactive proteins as compared with normal donors, we noted that the Con A-reactivity increased in patients with rheumatoid arthritis and systemic lupus erythematosus. Among all the glycoproteins examined by lectin blots with use of Con A, a set of five proteins was selected for detailed analysis by densitometric scanning. These included alpha 2-macroglobulin, P-150, P-95, P-40, and P-35, of Mr 180,000, 150,000, 95,000, 40,000, and 35,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Densitometric scanning analysis of the lectin blots revealed that the Con A-reactivity of these proteins increased during inflammation. Because alpha 2-macroglobulin is not an acute-phase protein in humans, an increase in Con A staining of this protein suggested that altered glycation is associated with autoimmune diseases. Thus, study of changes in Con A-reactive proteins in human sera may facilitate our understanding of the etiology and pathophysiology of autoimmune diseases.
A rapid, automated micromethod for measuring free fatty acids in plasma/serum.
Authors: Jeevanandam M , Hsu Y C , Ramias L , Schiller W R 
Published: January 2020

Abstract
The investigation of mobilization and utilization of fat as fuel in human subjects requires the quantification of free fatty acids (FFA) in the circulating plasma. Methods in current use involve tedious extraction and titration, or enzymatic reaction with colorimetric or fluorometric detections. A rapid and reliable micro-technique is needed. We have adapted the manual enzymatic method of the Wako NEFAC kit to an automated rapid assay performed with a micro-centrifugal analyzer. This method depends upon the specific acylation of CoA by FFA, followed by oxidation and condensation to form a purple adduct measurable at 550 nm. The acylation step requires incubation at 37 degrees C for 10 min, a critical step for serum/plasma analysis. Only 4 microL of plasma is needed, and 20 tests can be performed in 20 min. The precision (CV) of sample analysis is within 2%. The results for the samples analyzed by this technique are within 4% (SEM 1%) of results by the manual method. Thus accurate results are achieved at reduced cost, time, and sample size.
An improved pyrogallol red-molybdate method for determining total urinary protein.
Authors: Orsonneau J L , Douet P , Massoubre C , Lustenberger P , Bernard S 
Published: January 2020

Abstract
We adapted the pyrogallol red-molybdate method for total urinary protein to the Cobas Bio centrifugal analyzer. The method is simple, rapid, sensitive, and inexpensive. Addition of 25 mg of sodium dodecyl sulfate per liter to the reagent modifies protein reactivities so that the chromogenicity of human gamma globulins is the same as that of albumin. Results by this method and a comparison method that included gel filtration and a modified biuret reaction correlated well (r = 0.951).
Comparative results with five cannabinoid immunoassay systems at the screening threshold of 100 micrograms/L.
Authors: Wells D J , Barnhill M T 
Published: January 2020

Abstract
Five commercially available immunoassay techniques were compared for the detection of cannabinoid metabolites in urine at a positive cutoff of 100 micrograms/L. Numerical values, available for four of these techniques, were used to evaluate inter-assay equivalence at this threshold. The total number of positive results differed for each assay, with some individual samples exhibiting wide variations in numerical values. As a group, the radioimmunoassay systems gave a greater proportion of positive specimens than did enzyme-linked or fluorescence-polarization-based techniques. The single threshold of detection suggested by federal guidelines does not provide for equivalent screening of cannabinoids with these immunoassay techniques.
Time-resolved fluoroimmunoassay of aflatoxins.
Authors: Degan P , Montagnoli G , Wild C P 
Published: January 2020

Abstract
Preparation of purified and Eu-labeled antibodies specific for aflatoxins is described. Their use is illustrated by a solid-phase competitive time-resolved fluoroimmunoassay, results of which were correlated with those of an enzyme-linked immunosorbent assay based on use of the unmodified antibody to aflatoxin. This procedure is discussed as a quick, sensitive, and reliable immunoassay for use in mycotoxin screening in foodstuffs and body fluids.
Influence of O.C.T. embedding compound on determinations of estrogen and progestin receptors in breast cancer.
Authors: Pasic R , Djulbegovic B , Wittliff J L 
Published: January 2020

Abstract
Estrogen receptor (ER) and progestin receptor (PR) concentrations in tumor biopsies are important predictive indicators of a clinical response to endocrine therapy of breast cancer. To assess interference of O.C.T. (optimum cutting temperature) embedding compound in assays of ER and PR by radioligand binding, we determined specific binding capacities and affinities of ER and PR in cytosols by a multipoint titration method, using split samples of 14 breast-tumor biopsies, one portion serving as untreated control, the other treated with O.C.T. There was no statistically significant difference between these two groups. We then compared these data with those of historical controls analyzed both in the presence and absence of sodium molybdate (10 mmol/L). Eighty breast-tumor specimens (mean +/- SD patients' ages, 59 +/- 14 y) embedded in O.C.T. compound and analyzed without molybdate gave ER and PR values that differed insignificantly from those for 306 samples (patients' ages, 61 +/- 14 y) untreated with O.C.T. Thirty-nine specimens (patients' ages, 58 +/- 15 y) embedded in O.C.T. compound were analyzed in the presence of molybdate and compared with the results for 288 specimens (patients' ages, 61 +/- 14 y) untreated with O.C.T. Again, there was an insignificant difference in the concentrations and affinities of receptors in the two groups. Evidently O.C.T. compound does not alter the receptor status of tumor biopsies.
Lactate dehydrogenase isoenzyme composition of human platelets.
Authors: Miyada D S , Fagin A , Pirkle H , Ocariz J , Vaziri N D 
Published: January 2020

Abstract
The LDH isoenzyme composition of 12 platelet preparations was determined by electrophoresis. The mean (+/- SD) percentages of LDH-1, LDH-2, LDH-3, LDH-4, and LDH-5 were 16.6 +/- 1.7, 30.1 +/- 1.0, 34.2 +/- 1.3, 18.2 +/- 1.3, and 0.9 +/- 1.1, respectively. In comparison with previous data, these data show identical ranking of the prevalence of each isoenzyme but significantly different percentages, particularly of LDH-1 and LDH-4. The release of platelet LDH by freezing and thawing differed little from that by homogenization.
Usefulness of data on albumin and prealbumin concentrations in determining effectiveness of nutritional support.
Authors: Bernstein L H , Leukhardt-Fairfield C J , Pleban W , Rudolph R 
Published: January 2020

Abstract
In this ongoing study, albumin and prealbumin (transthyretin) changes were compared in 40 patients managed with enteral and (or) parental support with attainment of caloric/protein goals. The concentration of prealbumin in serum changed rapidly and more accurately reflected current nutritional status of these patients than did that of albumin. We determined concentrations of albumin and prealbumin that reflected significant improvement in nutritional status, using Rudolph's approach based on Shannon information measures. Reference values for albumin and prealbumin in the treatment populations were 25 g/L and 107 mg/L, respectively. A prealbumin concentration of 135 mg/L or greater reflected a return to stable status.
Detection of poisoning by plant-origin cardiac glycoside with the Abbott TDx analyzer.
Authors: Cheung K , Hinds J A , Duffy P 
Published: January 2020

Abstract
Cardiac glycoside poisoning caused by ingestion of plant material is common in tropical and sub-tropical areas. In evaluating the use of the Abbott TDx Digoxin II assay to detect such cases of poisoning, we found it a rapid and convenient method for confirming the ingestion of glycosides from the plants Nerium oleander, Thevetia peruviana, and Adonis microcarpa, and from the toad Bufo marinus. Here we report some clinical cases illustrating our experience with the use of this assay, and describe results of cross-reactivity studies with compounds structurally similar to digoxin. Because of the competitive nature of the immunoassay as well as the complexity of the mixture of cross-reacting cardiac glycosides present in the plant material, the measured apparent digoxin concentration is not linearly related to the cardiac glycoside concentration.
Patterns of lactate dehydrogenase isoenzymes 1 and 2 in serum of patients performing an exercise test.
Authors: Rotenberg Z , Weinberger I , Sagie A , Fuchs J , Davidson E , Sperling O , Agmon J 
Published: January 2020

Abstract
Values for total lactate dehydrogenase (LD, EC 1.1.1.27) activity and LD isoenzymes were determined in serum from 56 patients and 40 healthy subjects before and 24, 48, and 72 h after they performed an exercise test. The mean (for all four times) total LD activity concentration and proportion of LD-2 were within the normal range for all 96 subjects. Mean LD-1 values for serum, although within the normal range in all subjects, were significantly higher in patients with positive exercise test results than in subjects with negative results: 75 (SD 12) U/L in 35 patients with ST depression greater than 2 mm; 63 (SD 14) U/L in 16 patients with ST depression of 1-2 mm; 43 (SD 11) U/L in subjects with negative test results, by 48 h after the test. The LD 1:2 ratio was also markedly higher in the group of patients with positive test exercise results, especially in those with ST depression greater than 2 mm (1.02, SD 0.06), compared with those subjects with negative results (0.60, SD 0.04). A similar trend was also found 24 and 72 h after the exercise test. We conclude that exercise-myocardial ischemia may lead to an increased LD 1:2 ratio in serum, and demonstrate a correlation between the degree of ischemia and the LD 1:2 ratio. Determination of the LD 1:2 ratio, even in the presence of normal total LD activity, may assist in the clinical evaluation of patients performing an exercise test.
Assessment of renal function by inulin clearance: comparison with creatinine clearance as determined by enzymatic methods.
Authors: Apple F S , Benson P , Abraham P A , Rosano T G , Halstenson C E 
Published: January 2020

Abstract
We compared creatinine clearances determined by enzymatic (Kodak Ektachem 700 single-slide, Boehringer Mannheim creatinine PAP) and nonenzymatic (Jaffé, HPLC) methods with glomerular filtration rate measured by inulin clearance in patients with varying degrees of renal function. The Kodak enzymatic assay gave values for creatinine 2 to 3 mg/L higher than the other methods. This resulted in significantly lower creatinine clearances than inulin clearances and creatinine clearances determined by the other methods. However, correlations between all methods for serum and urinary creatinine values and clearances were good. To avoid between assay (enzymatic vs nonenzymatic) discrepancies, manufacturers should agree to an acceptable standard of calibration under the usual conditions used with patients.
Effectiveness of sodium fluoride as a preservative of glucose in blood.
Authors: Chan A Y , Swaminathan R , Cockram C S 
Published: January 2020

Abstract
How effective is sodium fluoride as a preservative of blood glucose? We compared changes in glucose concentration in fluoride-treated blood specimens with those of heparin-treated specimens. The former declined rapidly during the first hour; thereafter the rate of decrease was slower, and after 4 h the glucose concentration in the blood samples remained stable for up to three days. In contrast, the glucose concentration in the heparin-containing samples declined continuously. During the first hour, however, the rates of decline in the two types of samples were similar. Evidently sodium fluoride takes effect slowly but effectively in preserving glucose in blood for at least three days. Its use, however, is unnecessary if the concentration of glucose is to be measured within the first hour after sampling.
Measurement of apolipoprotein B in plasma from hyperlipidemic subjects treated with cholestyramine or placebo: differential effects of storage at -70 degrees C.
Authors: Kafonek S , Bachorik P S , Kwiterovich P O 
Published: January 2020

Abstract
Using radial immunodiffusion, we measured apolipoprotein B (apoB) concentrations in fresh plasma from 216 hyperlipidemic male subjects and in aliquots of the same plasma stored at -70 degrees C for 22 months. At the time of sampling, 112 were being treated with cholestyramine, the rest with a placebo. ApoB concentrations in the stored samples were significantly and positively correlated with apoB concentrations in the fresh samples (r = 0.84, P less than 0.001), the mean (and SD) being 1680 (320) mg/L and 1570 (320) mg/L, respectively. This 6.5% decrease in the stored samples was statistically significant (P = 0.0005), but there was no significant correlation between the decrease in apoB values in the stored samples and plasma triglyceride concentrations measured in the fresh samples. The correlation between the two apoB analyses was greater in the cholestyramine-treated group (r = 0.90) than in subjects treated with the placebo (r = 0.75).
Four immunochemical methods for measuring C-reactive protein in plasma compared.
Authors: Grützmeier S , von Schenck H 
Published: January 2020

Abstract
Four immunochemical methods for measuring C-reactive protein (CRP) in plasma were compared: radial immunodiffusion (RID), electroimmunoassay (EIA), immunoturbidimetry (IT), and laser nephelometry (LN). Close agreement was found between RID and EIA (EIA = 0.96 RID + 7.7 mg/L, r = 0.977, n = 100), IT and EIA (EIA = 1.11 IT - 15.8 mg/L, r = 0.951, n = 100), IT and RID (RID = 1.10 IT - 11.5 mg/L r = 0.959, n = 94). In initial studies in 1983, LN showed good agreement with RID (LN = 0.98 RID + 11.9 mg/L, r = 0.973, n = 60). Since then, normal CRP values measured by LN have tended to increase and, at the time of the present study (1986), LN agreed poorly with other methods. The reason for this change is obscure. Having excluded the possibility of enzymatic degradation of CRP, we conclude that instrumentation problems are involved, and therefore we no longer use this method.