bluuebunny/crossref_metadata_2025_split huggingface dataset:
New liquid-chromatographic method for measuring polyethylene glycol in urine.
Authors: Delahunty T , Hollander D 
Published: January 2020

Abstract
The various Mr fractions of polyethylene glycol (PEG) in human urine are quantified by "high-pressure" liquid chromatography. A simple preparation step involving lyophilization and chloroform extraction of the sample is required. Aliquots (10 microL) are chromatographed isocratically in equivolume mixtures of methanol and water on a column of styrene divinylbenzene and the refractive index of the effluent is measured. The results vary linearly with the concentrations of standards up to at least 10 g/L, and the six major fractions are clearly identifiable in injected samples containing 2 g or more of total PEG per liter. As little as 4 g/L can be precisely quantified, but for assessing the individual fractions, we recommend a minimum sample concentration of 7 g/L. Analytical recovery of PEG added to urine controls was 90%. Urines collected during 6 h from 11 human subjects after each had ingested 5.6 g of PEG showed no interference from endogenous compounds. We find this method to be a simple, labor-saving means of quantifying urinary PEG in the clinical laboratory.
Interlaboratory standardization of glycated hemoglobin determinations.
Authors: Little R R , England J D , Wiedmeyer H M , McKenzie E M , Mitra R , Erhart P M , Durham J B , Goldstein D E 
Published: January 2020

Abstract
As the clinical utility of glycated hemoglobin (gHb) measurement increases, so does the need for standardization of values between different methods and different laboratories. Using three different methods, we examined the feasibility of interlaboratory standardization of gHb measurement. A liquid-chromatographic (HPLC) system from our research laboratory was designated the reference method. For gHb standards we used erythrocyte hemolysates prepared from blood samples from nondiabetic and diabetic subjects. Values assigned to each standard were based on the mean of multiple gHb determinations by the HPLC method. A clinical laboratory routinely prepared hemolysates and assayed gHb by commercially available ion-exchange ("mini column") and affinity chromatographic methods. For each assay a standard curve was constructed and gHb values were derived from these curves. Samples analyzed in the clinical laboratory were also analyzed in the research laboratory and the curve-derived values were compared with the HPLC-measured values, to determine the accuracy of our interlaboratory standardization procedure. Correlations were excellent (r = 0.99). The lack of significant differences between calculated and HPLC-measured values indicates that interlaboratory standardization is feasible.
Practical "stat" method for radioimmunoassay.
Authors: Cembal S J 
Published: January 2020

Abstract
A prompt and reasonably precise radioimmunoassay result is often urgently required, but it is difficult to satisfy such requests without running a complete standard curve, even when only a single sample is to be assayed. To obtain a greater constancy in the response of the RIA system, I propose a method for use of RIA in a "stat" (i.e., urgent) method: maximum binding and nonspecific binding for RIA data processing are "calculated" from response indexes obtained in a previous assay run with the same reagents and from the binding values of two or three standards processed together with a single sample. These calculated values are then used to calculate the response index for the single sample, which is directly interpolated in the calibration curve of the previous non-stat assay. I checked the validity of this stat method for eight analytes, comparing a total of 552 analytical results obtained by the conventional and the stat method. This method is shown to give adequately precise results for use in clinical emergencies.
Progesterone in saliva does not parallel unbound progesterone in plasma.
Authors: Evans J J 
Published: January 2020

Abstract
To assess the potential application of salivary progesterone, in light of the voluminous published information on blood progesterone, I compared plasma and salivary progesterone in paired samples and found that they exhibit similar patterns, both having high concentrations in the second half of the cycle. However, the ratio between values for plasma and saliva changed during the cycle. I observed no concomitant changes in binding of progesterone to plasma proteins, which might have been expected if the concentrations in saliva reflect those of non-protein-bound steroid in plasma. There was some binding of progesterone by salivary proteins, but the proportion of progesterone so bound apparently remained constant during the cycle. Data on progesterone in saliva must therefore be interpreted with awareness of the properties of saliva, and not simply as "free" plasma progesterone.
Fluorescence polarization immunoassay for theophylline modified for use with dried blood spots on filter paper.
Authors: Li P K , Lee J T , Conboy K A , Ellis E F 
Published: January 2020

Abstract
We used dried blood spots successfully as alternative specimens for quantifying concentrations of theophylline in the circulation by a modified fluorescence polarization immunoassay (FPIA) with the Abbott TDx instrument. The method described is simple, rapid, and acceptably precise. More importantly, it can provide results comparable with those of the conventional serum assay. Results for 64 pairs of dried blood spots (y) and serum (x) specimens analyzed by the respective FPIA methods yielded the following regression parameters: y = 0.94x + 0.71, r = 0.988, and Sxy = 0.92. A major advantage of FPIA is that it requires only basic laboratory skills. When coupled with the use of dried blood spots, this system can be effective in remote theophylline monitoring, particularly suited for domiciliary care.
Binding characteristics of thyroxin binding globulin in serum of normal, pregnant, and severely ill euthyroid patients.
Authors: Maberly G , Waite K , Ma G , Soni N , Eastman C 
Published: January 2020

Abstract
Serum from normal, pregnant, and severely ill patients was stripped of endogenous thyroid hormones and diluted 1100-fold in barbital buffer. We then used it to study the binding characteristics of thyroxin binding globulin (TBG), noting significant differences in binding capacities among the groups. The mean (+/- SD) triiodothyronine/thyroxin ratio for binding capacity was 18 +/- 4 for normal subjects. The ratio was significantly increased in pregnant patients, 21 +/- 4 (p less than 0.05), and significantly lower in severely ill patients, 12 +/- 4 (p less than 0.05). When serum was diluted before assay, to give a uniform TBG concentration among groups, these apparent differences in binding characteristics were eliminated. It therefore is unlikely that different molecular species of TBG account for the variations in binding characteristics in these clinical states. Apparently, the distribution of thyroxin and triiodothyronine among the binding sites on TBG changes with variations in TBG concentration. This may explain the discrepancies observed in the concentrations of free thyroid hormones as estimated by various methodologies.
A kinetic colorimetric procedure for quantifying magnesium in serum.
Authors: Wimmer M C , Artiss J D , Zak B 
Published: January 2020

Abstract
We have developed a kinetic colorimetric procedure for determination of magnesium in serum. The magnesium-dependent enzyme glycerol kinase is used to phosphorylate glycerol to glycerol 3-phosphate, the latter being oxidized to dihydroxyacetone phosphate and hydrogen peroxide by glycerophosphate oxidase. The generated hydrogen peroxide is then reduced by peroxidase with the simultaneous oxidative coupling of 4-aminoantipyrine and 2-hydroxy-3,5-dichlorobenzenesulfonate, producing a red reaction product with an absorption maximum at 510 nm. The rate of color production is proportional to the concentration of the Mg X ATP complex, which is, in turn, proportional to the magnesium concentration in serum. This method is rapid and precise, avoids the use of expensive instrumentation, is easily automated, and results compare well with those by the Du Pont aca and manual Magon sulfonate methods.
Isolation and characterization of an abnormal alpha slow-moving high-density lipoprotein subfraction in serum from children with long-standing cholestasis.
Authors: Peynet J , Fénéant-Thibault M , Legrand A , Marot D , Rousselet F , Lemonnier A 
Published: January 2020

Abstract
An abnormal high-density lipoprotein (HDL) subfraction, detected during periods of mild jaundice in the serum of seven children with chronic cholestasis from birth, was isolated and characterized. This fraction, identified by its slow alpha electrophoretic migration, is present in addition to normal HDL and differs from the abnormal HDL previously described in cholestatic syndromes. It is devoid of apolipoprotein B but is precipitated by phosphotungstate-MgCl2. These properties allowed its isolation by double selective precipitation. This subfraction is undetectable with this procedure in the serum of healthy subjects, is rich in cholesterol, and contains a large amount of apolipoprotein E, which may explain its precipitation by phosphotungstate-MgCl2. These apo E-containing HDL may play a major role in the lipid metabolism of patients with long-standing cholestasis during periods of mild jaundice.
Determination of vanillylmandelic acid with ion-pair chromatography and fluorescence detection.
Authors: Lindgren K , Rodopoulos N 
Published: January 2020

Abstract
We describe a chromatographic procedure for sensitive (2.0 mumol/L), specific quantification of vanillylmandelic acid (VMA) in urine with iso-VMA as an internal standard. After rapid extraction from urine, the VMA is determined by isocratic reversed-phase ion-pair chromatography on a bonded C8 column and detection of the native fluorescence on excitation at 285 nm. The fluorescence signal is quite dependent on the pH of the mobile phase. Results by the method vary linearly with VMA concentration up to 320 mumol/L and correlate well (r = 0.9880) with those obtained by conventional ultraviolet spectrophotometry. The mean 24-h excretion of VMA from 29 healthy volunteers was 21.4 (SD 5.4) mumol.
Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.
Authors: Smith D A , Moses G C , Henderson A R 
Published: January 2020

Abstract
We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.
Myoglobinemia after burn injury: relationship to creatine kinase activity in serum.
Authors: Guechot J , Lioret N , Cynober L , Letort C , Saizy R , Giboudeau J 
Published: January 2020

Abstract
Myoglobin is released into the blood after burn injury. We measured it and other analytes in blood collected from 22 burn patients two to seven times during their recovery. There was a significant correlation between myoglobinemia and creatine kinase (CK) activity in serum (r = 0.764; p less than 0.001). In a group of 14 thermal-burn subjects a correlation was found between burn depth (clinically expressed as Unit Burn Surface) and both myoglobinemia (r = 0.825; p less than 0.01) and CK activity (r = 0.686; p less than 0.01). In eight thermal-burn patients who were recovering satisfactorily, myoglobin and CK activity measured on days 2, 4, 7, 10, and 13 after injury were significantly increased (p less than 0.05) on days 2, 4, and 7. Evidently myoglobinemia and CK activity are good biological markers of burn depth, and reflect muscle damage equally well.
Collection of blood on filter paper for measurement of glycated hemoglobin by affinity chromatography.
Authors: Little R R , McKenzie E M , Wiedmeyer H M , England J D , Goldstein D E 
Published: January 2020

Abstract
We present data on a filter-paper collection and assay method for measurement of glycated hemoglobin (gHb). Onto filter paper dipped into a solution of glucose oxidase (EC 1.1.3.4) and allowed to dry, approximately 20 microL of capillary blood was spotted. For analysis, we eluted the dried blood spot from the paper by soaking in water for 1 h, then measured the gHb in the eluate by affinity chromatography. Because the gHb significantly increased from day 1 to day 14 of storage, it was necessary to standardize the day of elution from the paper. We found a high correlation between gHb measured from samples stored for 14 days on treated paper and gHb measured by affinity chromatography from frozen whole blood or hemolysates (r = 0.96). This method is convenient, requiring small amounts of blood and little sample handling and assay time, and may be particularly useful in certain situations such as large-scale screening for diabetes.
Simple liquid-chromatographic determination of urinary coproporphyrin in workers exposed to lead.
Authors: Tomokuni K , Hirai Y 
Published: January 2020

Abstract
We developed a simple method for the determination of urinary coproporphyrin (CP) in lead workers, using a "high-performance" liquid chromatograph (HPLC) equipped with a fluorescence detector. The detection limit of urinary CP in this method was 5 micrograms per liter of urine. The working linear range of urinary CP concentration was 5 to 1500 micrograms/L. In 41 lead-exposed workers, the urinary CP values obtained by the present HPLC method were well correlated with those obtained by a conventional spectrophotometric method (r = 0.94). The present method is useful for screening workers exposed to lead.
Liquid-chromatographic determination of 4-hydroxyproline in urine.
Authors: Hughes H , Hagen L , Sutton R A 
Published: January 2020

Abstract
In this method for 4-hydroxyproline in urine, hydroxyproline is derivatized with 4-chloro-7-nitrobenzofurazan, with subsequent estimation by reversed-phase "high-performance" liquid chromatography. The ranges for excretion of free and total hydroxyproline while the subjects were ingesting unrestricted diets were 2-29 and 122-374 mumol/24 h (n = 21), respectively, with no significant sex-related difference. A comparison with results by colorimetry indicated no significant differences: mean (n = 18) concentrations (mumol/L) of hydroxyproline in urine were 180 (SD 149) by the present method, 163 (SD 166) by colorimetry. For protein hydrolysate the respective values were 5.9 (SD 2.7) and 6.7 (SD 2.9).
Serum thyrotropin as measured with a one-step monoclonal-antibody radioimmunometric assay compared with two commercial radioimmunoassay kits.
Authors: Pekary A E , Hershman J M 
Published: January 2020

Abstract
We compared results obtained with a commercial immunoradiometric assay kit for human thyrotropin in which monoclonal antibodies are used (Tandem -R TSH (ONE STEP) ImmunoRadioMetricAssay; Hybritech Inc.) with those obtained with two commercial radioimmunoassay methods: GAMMA-DAB [125I]HS-hTSH RIA (Clinical Assays) and Thyro-SHure TSH Diagnostic Kit (Nuclear Medical Laboratories). The correlation of all results obtained in the Hybritech assay with those of the two commercial RIAs exceeded 95%. Mean values for 100 euthyroid samples measured in the Hybritech assay were lower than for the other two methods. The separation between hyperthyroid and euthyroid patients was much clearer with the Hybritech assay than with the RIA methods. The Hybritech assay was far more sensitive than the Clinical Assays or the Nuclear Medical Laboratories assay.
Perchloric acid interference in enzymatic-fluorimetric-continuous-flow assay methods for measuring glucose, lactate, pyruvate, alanine, glycerol, and 3-hydroxybutyrate in blood.
Authors: Stappenbeck R , Hodson A W , Skillen A W 
Published: January 2020

Abstract
Perchloric acid is commonly used to denature and precipitate proteins in samples before various metabolites are measured in tissue, blood, and other body fluids. However, perchloric acid can interfere in the analytical process, possibly by inhibiting the enzymes used. We have determined the effects of perchloric acid on measurements of glucose, lactate, pyruvate, alanine, glycerol, and 3-hydroxybutyrate in blood by enzymatic-fluorimetric-continuous-flow assays. There was a net increase or decrease in the apparent concentration of some of these metabolites when the perchloric acid concentration in the samples differed from that of the reference standards-some of these differences were due to the concentration of perchlorate ion and some to the pH of the acid extracts. The results show the need either to add a fixed amount of blood to perchloric acid or to neutralize and remove the perchlorate.
Interlaboratory testing of the transferability of a candidate reference method for total cholesterol in serum.
Authors: Cooper G R , Smith S J , Duncan I W , Mather A , Fellows W D , Foley T , Frantz I D , Gill J B , Grooms T A , Hynie I 
Published: January 2020

Abstract
In 1975 the Centers for Disease Control, in cooperation with the American Association for Clinical Chemistry Cholesterol Reference Method Study Group, began an investigation to develop a reference method for total cholesterol. Five potential reference methods were compared with the definitive method developed by the National Bureau of Standards before the chemical method of Abell et al. (J Biol Chem 1952;195:357-66) was selected as the recommended reference method. Because acceptance of a proposed reference method depends so greatly on the method's capability for transfer to other laboratories by written specifications and instructions, a transferability testing study was designed and conducted with 14 laboratories. The study consisted of preliminary testing of readiness of equipment, reagents, and personnel followed by transferability testing with eight runs on 10 serum pools. Laboratoires that did not meet readiness specifications had higher CVs in the transferability testing. The study demonstrated that the proposed method permits laboratories to attain a CV of less than 1.5% for one laboratory and of less than 3.0% among laboratories. The mean percent bias value was less than 1.0% for six of the 14 laboratories, less than 1.5% for 12, and less than 3.0% for all 14 laboratories.
Apoprotein A-I measured by radial immunodiffusion in heparin-MnCl2 supernates.
Authors: Jiang X R , Bachorik P S 
Published: January 2020

Abstract
We compared measurements of apoprotein A-I (apoA-I) in plasma and in heparin-MnCl2 supernates analyzed by radial immunodiffusion. The apoA-I values were similar when the samples were fresh [n = 41, mean (SD), mg/L: plasma, 1393.4(349); heparin-MnCl2 supernates, 1364.9(332), p less than 0.01], but were greater than 8% lower in heparin-MnCl2 supernates after storage for seven days at 4 degrees C [plasma, 1348.0(351); heparin-MnCl2 supernates, 1237.6(342), p less than 0.001]. Neither heparin nor MnCl2 interfered directly with the immunodiffusion assay, and treating samples with tetramethylurea and urea to maximize the exposure of apoA-I did not prevent the decrease. MnCl2 (46 mmol/L) added to isolated HDL (d 1.063-1.21) decreased apoA-I values by 5.6% when measured immediately and by 16.7% after storage at 4 degrees C for seven days. High-density lipoprotein cholesterol values were unchanged by MnCl2. The results indicated that apoA-I was more stable in plasma than in heparin-MnCl2 supernates, probably because of an interaction between apoA-I and MnCl2.
Liquid-chromatographic determination of hyaluronic acid in pleural and ascitic fluids.
Authors: Hjerpe A 
Published: January 2020

Abstract
A previously described method for determination of hyaluronic acid is modified for the analysis of pleural and ascitic fluids. After 20 microL of the acellular supernate is precipitated with ethanol, the precipitate is digested overnight with chondroitinases and chondroitin sulfatases. The content of hyaluronic acid-derived disaccharide is then analyzed by "high-performance" liquid chromatography. The high sensitivity (detection limit, less than 0.1 microgram of hyaluronate-derived uronic acid per milliliter) and reproducibility (SD = 4% of the mean) enable accurate determination of hyaluronic acid, even in effusions from patients without signs of mesothelioma. The range of values obtained for pleural and ascitic fluids from patients without signs of this kind of tumor is the same as that found by using other techniques, being slightly higher in those patients showing signs of tissue destruction. The concentrations of hyaluronic acid were considerably increased in most, but not all, of the cases of mesothelioma.
Resolution of alkaline phosphatase isoenzymes in serum by isoelectric focusing in immobilized pH gradients.
Authors: Sinha P K , Bianchi-Bosisio A , Meyer-Sabellek W , Righetti P G 
Published: January 2020

Abstract
This new method for fractionation of serum alkaline phosphatase isoenzymes is based on isoelectric focusing on a mixed-type polyacrylamide support containing an immobilized pH gradient with a superimposed carrier-ampholyte gradient. All known forms of alkaline phosphatase are separated in an Immobiline pH 3.5-6.0 gradient, the sample being applied into pockets cast on a pH 8.0 plateau. Sharp zymogram bands are obtained by substituting alkaline-stable 5-bromo-4-chloro-3-indoxyl phosphate and tetrazolium salts for the standard 1- and 2-naphthyl phosphate-diazonium salt combinations. After hydrolysis of the phosphate group by the alkaline phosphatase the indoxyl moieties reduce tetrazolium salts to nearly insoluble and nondiffusible formazan precipitates. Normal sera show an array of about 10 isobands isoelectric between pH 3.9 and pH 4.79. In Paget's disease, two sharp isobands with pls of 4.97 and 5.09 are seen. Placental alkaline phosphatase overlaps with the higher pl bands of normal serum; however, upon heat destruction of the latter, it shows four sharp bands with the following pl's: 4.59, 4.62, 4.67 and 4.73.
Use of a new sample-collection device (Macroduct) in anion analysis of human sweat.
Authors: Cole D E , Boucher M J 
Published: January 2020

Abstract
We compared concentrations of chloride and sulfate in sweat obtained by use of the Macroduct capillary-coil collection device with results obtained by the conventional absorbent filter pad technique. Samples obtained with the device weighed less than those obtained conventionally, but sweat chloride concentrations were not significantly different. To assess analysis of trace anions, we used inorganic sulfate as a prototype. Background contamination, a problem with the filter pads, was negligible with the Macroduct collector. However, with the Macroduct device, sulfate concentrations were nominally higher than with the conventional pads (105 +/- 6 vs 88 +/- 5 mumol/L) and showed no dependence of sulfate concentration on sweat rate. Subtraction of the significant "background" SO4 concentration obtained with blanks (i.e., unused filter pads) is a likely source of error in the conventional method. We consider the Macroduct device useful for study of trace constituents of human sweat.