bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic determination of serum haptoblobin with a centrifugal analyzer.
Authors: Kickler T S , Gong P F , Johnson G F , Solomon H M 
Published: January 2020

Abstract
We describe a method for determining haptoglobin with a centrifugal analyzer that is based on haptoglobin combining stoichiometrically with hemoglobin to form a complex that has peroxidase-like activity proportional to the quantity of haptoglobin present. Under assay conditions, unbound hemoglobin exhibits only a small fraction of the total peroxidase activity. Activity is measured colorimetrically at 405 nm after reaction with o-dianisdine and ethyl hydrogen peroxide. The procedure is standardized by saturating aknown amount of hemoglobin with a serum whose hemoglobin binding capacity exceeds the amount of hemoglobin in the assay system. The mean and mean within-run precision of our method, determined by performing 17 replicate assays of both a pooled normal serum and a 10-fold dilution of the serum, was 1.13 g/liter (CV, 2.9%), and 106 mg/liter (cv, 5.8%), respectively. The 95 percentile estimate of the normal range by our method is 0.45-1.85 g/liter hemoglobin binding capacity. When results by our automated method were compared to those by a manual method [Scand. J. Clin. Lab. 2nvest. 18, 80 (1965)], the slope of the unweighted linear least-squares regression line was .970 the y-intercept 26 mg/liter, and the correlation coefficient .995.
A mechanism for the conversion of oxyhemoglobin to methemoglobin by nitrite.
Authors: Rodkey F L 
Published: January 2020

Abstract
Each mole of oxyhemoglobin iron converted to methemoglobin causes the oxidation of 1.5 mol of nitrite to nitrate and consumes 1 mol of protons. No oxygen is liberated. The overall reaction has two simultaneously occurring parts. In the beginning the rate-limiting reaction converting O2Hb to metHb is directly proportional to H+ and NO2- concentrations and is independent of metHb. The second portion accounts in major part for the stoichiometry and rate of the overall reaction. In this portion O2Hb tetramers and metHbNO2- are the reactants. Essentially no reaction takes place in the presence of CN-, which displaces nitrite from the metHbNO2-, nor in the presence of 0.5 mol/liter Nal, which converts the O2Hb to alphabeta-dimers. The autocatalytic nature of the overall reaction in the presence of excess nitrite is the result of metHb, which is formed in both parts of the reaction, associating with nitrite to increase the concentration of one reactant of the cyanide-sensitive part. The reaction rates at constant pH in excess nitrite are porportional to the product of the O2Hb concentration and the square of the metHb concentration. The rate increases up to about 66% conversion of O2Hb followed by a decrease as the O2Hb becomes limiting. The dissociation constant of metHbNO2- at 25 degrees C and pH = 6.4 was found to be 1.11+/-0.11 mmol/liter.
Relation of pH to fluorescence of serotonin, melatonin, and other indole compounds reacted with o-phthaldialdehyde.
Authors: de Leiva A , Schwartz S 
Published: January 2020

Abstract
We distinguished serotonin, malatonin, and other indole compounds by their markedly different fluorescence behavior when heated with o-phthaldialdehyde in different concentration of HCl, or after the subsequent addition of alkali. Fluorescence may increase, disappear, or change from blue to orange-red. Only melatonin developed significant fluorescence (at less than 0.5 mug/liter) when heated with the reagent in 50 mmol/liter HCl. Serotonin and 5-hydroxyindole compounds with a C-3 aliphatic chain lost their blue fluorescence when brought from strong to weakly acid and alkaline pH. Intense reddish fluorescence developed in strongly alkaline solution. C-5 methoxy derivatives, such as melatonin, maintained their blue fluorescence in alkaline solution. Differences in fluorescence color (and RF) also characterized these compounds on silica gel plates. The use of toluene decreased blank fluorescence, while sample preparation in dim light, as often recommended, resulted in diminished and less-stable fluorescence.
Enzymatic Rate Method for Measuring Cholesterol in Serum
Authors: Pesce Michael A , Bodourian Selma H 
Published: January 2020

Abstract
An enzymatic rate assay is described for measuring cholesterol in serum. Cholesterol is anzymed by mixing 5 µl of sample with a reagent consistaing of cholesterol esterase, cholesterol oxidase, catalase, acetylacetone, methanol. and hydroxypolyethoxydodecane in a ammonium phosphate of the dihydrolutidine product is measured at 37 °C and 405nm. The change in absorbance between 4 and 10 min is used to calculated the cholesterol concentrations by using simultaneously determined free cholesterol standards. The change is linearly ralated to cholesterol concentration up to 4 g/liter. Samples containing bilirubin up to 200 mg/liter, uric acid up to 200 mg/liter, and hemoglobin up to 1 g/liter, or certain drugs (clofibrate, phenobarbital, nicotinic acid, salicylate, Ketochol, and Ovral) gave no interference. Ascorbic acid added to serum caused a positive interference. Lipemic samples gave values that were slightly lower than did the method of Abell et al., used for comparison. Our kinetic assay, compared with the method of Abell et al., the enzymatic assay used with Abbott's Bichromatic Analyzer, and the Technicon SMA 12/60 enzymatic procedure gave correlation coefficient of 0.992, 0.985, and 0.986, respectively.
Sample stability: a suggested definition and method of determination.
Authors: Thiers R E , Wu G T , Reed A H , Oliver L K 
Published: January 2020

Abstract
We propose defining the stability of any chemical constituent of stored samples in terms that are quantitatively related to the precision of the measurement by which it is determined. We suggest that a constituent may be considered stable, for a stated period and under exactly defined conditions, when the average change in its measured value is less than a chosen number, K, of standard deviations of the data obtained by the measuring method over the concentration range in question. Based on this definition a technique utilizing a graphical truncated normal sequential test is presented as the appropriate experimental and statistical design for measuring stability. The statistical basis for the proposal is presented.
Analysis for indole compounds in urine by high-performance liquid chromatography with fluorometric detection.
Authors: Graffeo A P , Karger B L 
Published: January 2020

Abstract
We describe a chromatographic system involving a high-performance chemically-bonded reverse-phase column and fluorescence detection for measurement of indoles in urine. We controlled retention and selectivity by optimizing the methanol content and pH of the mobile phase. Six reference indoles were separated in less than 20 min; three 5-hydroxyindoles were eluted in less than 7 min. About 5-15 ng of aqueous solutions of these compounds can be detected. The combination of selectivity (from use of the chromatographic column) and fluorescence detection permitted analysis for five of the six indoles after a single urine-deproteinization step.
Improved assay for urinary 17-hydroxycorticosteroids.
Authors: Ariyoshi Y , Osawa Y 
Published: January 2020

Abstract
We describe a simple, rapid, reliable method for determining urinary 17-hydroxycorticosteroids. A neutral resin (Amberlite XAD-2), which is a non-ionic cross-linked polystyrene, is used to extract and concentrate the steroids, which are then quantitatively determined with the Porter-Silber reaction. Use of the resin eliminates the need for enzymatic hydrolysis and n-butanol extractions, thereby decreasing analysis time considerably; results can be obtained within 3 h of receipt of specimens. Most of the nonsteroidal Porter-Silber chromogens are removed, resulting in a method that is highly specific and sensitive, even at low concentrations (0.6 mg/liter), and so more accurate and reproducible than currently used methods.
Assessment of a serum separator device for obtaining serum specimens suitable for clinical analyses.
Authors: Laessig R H , Westgard J O , Carey R N , Hassemer D J , Schwartz T H , Feldbruegge D H 
Published: January 2020

Abstract
We have evaluated a serum separator device that is designed to effect better separation and isolation of serum from clotted blood. This device consists of an evacuated blood-drawing tube (Vacutainer) containing 1.5 ml of a semi-solid silicon polymer that forms a barrier between serum and clot during centrifugation. We compared test specimens with conventionally processed (Vacutainer) specimens as controls. Eighty-one chemical, toxicological, and immunological reactions, tests, or methods were studied. For several tests we observed changes that are statistically but not clinically significant. The one clinically significant change in serum chemistry values occurred in the case of lactate dehydrogenase, for which values were increased by 5-8% of the upper limit of normal.
Radioimmunoassay of plasma renin activity.
Authors: Fyhrquist F , Soveri P , Puutula L , Stenman U H 
Published: January 2020

Abstract
We describe a sensitive, simplified radioimmunoassay method for determination of plasma renin activity. Plasma was acidified to the optimal pH (6.0) of angiotensin l generation with the least possible dilution, by using a single addition of hydrochloric acid and the enzyme inhibitor hydroxyquinoline. Recovery of unlabeled angiotensin l added to plasma was 92-97%; that of monoiodinated angiotensin l exceeded 90%, indicating satisfactory protection from proteolytic enzymes. Plasma constituents interfered little with the radioimmunoassay. Bland values for plasma kept at 0 degrees C were 10.7 +/- 2.3 (mean +/- SD) percent of the activity values for samples kept at +37 degrees C (n equals 63). In the routine setting, 6.25 pg of angiotensin l or 10(-6) Goldblatt units of Standard Human Renin was detected. We report results of plasma renin activity measurements and a comparison with seven renin kits, and with bioassay for plasma renin activity.
Use of polyethylene glycol in separating bound from unbound ligand in radioimmunoassay of thyroxine.
Authors: Cheung M C , Slaunwhite W R 
Published: January 2020

Abstract
In most rapid radioimmunoassay methods, absorbents are used that disturb the equilibrium of the ligand-antibody interaction; thus the separation process must be rigidly timed. We show here that polyethylene glycol (mol wt. 6000) abolishes this constant. We measured gamma-globulin precipitation by polyethylene glycol (150g/liter) in a thyroxine radioimmunoassay system involving use of a sheep anti-thyroxine antiserum, quantitatively and qualitatively, with either normal human serum or completely precipitated at pH 6-9 at 4 and 25 degrees C, but incompletely if salt concentration was high (1 mol/liter). Specificity of gamma-globulin precipitation increased with increasing pH and temperature. All gamma-globulin-bound thyroxine was precipitated, and also some not bound to gamma-globulin. This was taken into account by including "blank" tubes (no antibody, but with normal sheep serum) in all assays. Because this reaction is predominantly entropic and temperature independent, the entire procedure can be done at 37 degrees C and room temperature without rigid timing. The assay requires 10 mul of serum, its reproducibility is 4-8% (CV) in the euthyroid and hyperthyroid range, and its accuracy is close to 100%.
Determination of apolipoprotein A and its constitutive A-I and A-II polypeptides by separate electroimmunoassays.
Authors: Curry M D , Alaupovic P , Suenram C A 
Published: January 2020

Abstract
Electroimmunoassays ("rocket" electrophoresis) are described for human serum apolipoprotein A and its constitutive A-I and A-II polypeptides. Purified lipoprotein A, A-I, and A-II were used to prepare monospecific antisera and to standardize assays. These specific, rapid (5-8 h), precise (the within-and between-assay coefficients of variations are 5 and 7%, respectively), and accurate (by gravimetry) assays are applicable to measurement of these polypeptides in whole serum and in various density classes of lipoproteins. Comparable results are obtained with intact and delipidized lipoproteins. Results correlated well with those obtained by radial immunodiffusion or radioimmunoassay. However, the present procedure is more rapid than the former and simpler than the latter immunoassay. Concentrations of A-I and A-II in the serum of normal men and women were similar (143 +/- 24 and 146 +/- 78 mg/dl, respectively, for A-I and 78 +/- 17 and 83 +/- 25 mg/dl for A-II). Subjects with type lla, llb, and IV hyperlipoproteinemias had similar concentrations of both polypeptides, while patients with type I disease, lecithin:cholesterol acyltransferase deficiency and LP-A deficiency had lowest concentrations of A-I (0.3-30 mg/dl) and A-II (11-20 mg/dl). The molar ratio of A-I/A-II in the serum and high-density lipoproteins was close to unity.
Evaluation of methods of coenzyme activation of erythrocyte enzymes for detection of deficiency of vitamins B1, B2, and B6.
Authors: Bayoumi R A , Rosalki S B 
Published: January 2020

Abstract
We describe optimized, ultraviolet spectrophotometric procedures for determination of erythrocyte transketolase, glutathione reductase, and aspartate aminotransferase activity, and their activation by their respective coenzymes--thiamine pyrophosphate, flavin-adenine dinucleotide, and pyridoxal-5-phosphate--as tests for vitamin B1, B2, and B6 deficiency. With these procedures we have investigated healthy subjects on normal and vitamin-supplemented diets, and a series of (mainly) alcoholic hospital in-patients. The enzyme procedures described have good precision and can be readily carried out in the routine laboratory. Abnormal transketolase activation correlated well with clinical evidence of vitamin B1 deficiency.
Method for monitoring plasma progesterone concentrations in pregnancy.
Authors: Winkel P , Gaede P , Lyngbye J 
Published: January 2020

Abstract
We present a time-series model for monitoring concentrations in plasma of hormones produced in the placenta, progesterone being chosen as an example. The model, which is based on the assumption that variations in plasma progesterone concentration in pregnant subjects mainly reflect variations in the growth rate of the placenta, was applied to eight series of progesterone values measured during pregnancy in eight subjects. In the model, which was found to fit the data, it is assumed that progesterone concentration is proportional to the size of the placenta and that the growth rate of the placenta varies at random, with a mean value alpha. The variation of alpha was of the same magnitude among and within the subjects. If the average of many subjects alpha values is used, a single subject may be used as her own reference, based on only one previous observation. When two observations are available, an individual's own alpha value may be estimated and used for the prediction. The predictive power of the new method was found to be far superior to the conventional method in which a single sample reference material is used. Furthermore, one need not know the gestational age in order to use the method.
Development of an aqueous temperature-indicating technique and its application to clinical laboratory instrumentation.
Authors: Bowie L , Esters F , Bolin J , Gochman N 
Published: January 2020

Abstract
We describe a new technique for monitoring intra-cuvette temperatures in temperature-controlled spectrophotometric cells by use of two solutions, one for which absorbance is highly sensitive to temperature and one for which absorbance is insensitive to temperature. The first solution, cresol red in tris(hydroxymethyl)aminomethane buffer, is used to construct an absorbance-vs.-temperature calibration curvae. The second solution, cresol red in sodium hydroxide, is used for optical calibration of the spectrophotometric system to be tested. The combination of these two procedures allows accurate estimation of temperature. We show how this technique is applied to temperature measurement in several types of laboratory instrumentation.
Expression of random analytical error as a precentage of the range of clinical interest.
Authors: Glick J H 
Published: January 2020

Abstract
I propose that random method error be expressed as a percentage of the range(s) of clinical interest (upper range limit minus lower range limit), in addition to its usual forms of presentation. The interpretation of this percent random error is simple because a given percentage error implies the same reliability, regardless of test or range of clinical interest. Two different upper limits for percent random analytical error are suggested, based on the medical application of the test and the statistical properties of various amounts of error. When the purpose of the test is to distinguish an upper medically defined limit from a lower medically defined limit, a maximum random error equivalent to 60% of the difference between the limits is proposed. If the purpose of the test is to monitor values in the neighborhood of a normal range or therapeutic range, an upper limit for random error equal to 20% of the difference between the limits of the range is suggested.
Immunofixation. I. General principles and application to agarose gel electrophoresis.
Authors: Ritchie R F , Smith R 
Published: January 2020

Abstract
Immunofixation offers the worker an economical means of physically locating a protein in an electrophoretic strip and is ideally suited to forensic medicine, genetic studies, or research. The method is as simple and economical as the commonly used one- or two-dimensional immunoelectrophoresis, yet yields considerably more information.
Fast, economical technique for separating serum from blood samples.
Authors: Ahluwalia G S , Kuczala Z J , Carlson L R 
Published: January 2020

Abstract
We evaluated the effectiveness with which polystyrene beads separate serum from blood. Paired blood samples were analyzed for 23 different serum constituents. One specimen of each pair was processed by the conventional separation method, the other by a single centrifugation with the polystyrene beads. Differences between the assay means were evaluated by the z-test, and the data pairs were compared by regression analysis. No statistically significant differences were found.
Evaluation of a new enzymatic kit for serum triglycerides.
Authors: Carter T , Martin P J , Wilding P , Goldberg D M 
Published: January 2020

Abstract
We evaluated a new enzymatic kit for serum triglycerides (triacylglycerols) in two laboratories. The procedure involved both enzymatic hydrolysis of the triglycerides and conversion of the glycerol, which was linked to an indicator reaction. There was excellent agreement with the mechanized procedure of Kessler and Lederer and with a manual method. The test requires 50 mul of serum and can be completed in about 50 min. Inter- and intra-laboratory variation, linearity, accuracy, and specimen storage were studied.
Improved specificity of serum albumin determination and estimation of "acute phase reactants" by use of the bromcresol green reaction.
Authors: Gustafsson J E 
Published: January 2020

Abstract
The reaction of serum samples with bromcresol green proceeds in two steps. Albumin is responsible for the faster (less than 1 min) reaction; the slower (30-min) reaction is a measure of "acute phase reactant(s)" in serum. Serum is simply mixed with bromcresol green reagent and the absorbance is measured twice, immediately and at 60 min. Albumin concentrations, determined from the absorbance at 0 min, correlate well with those determined by Laurell "rocket" immunoelectrophoresis; r = 0.95 with no certain deviation from unity for the slope and with a negligible difference at zero concentration. The slow reaction was expressed as deltaA% = 100 (deltaAs/deltaAv) where deltaAs and delta Av are the changes in absorbance between 60 and 0 min for the sample and a commercial control serum, respectively. The value for deltaA% correlates well with the percentage of alpha2-fraction as determined by electrophoresis on cellulose acetate, as well as with orosomucoid and ceruloplasmin, all of which are acute phase reactant(s). Whether these proteins or other acute phase reactant(s) actually cause the slow reaction has not yet been established.
Evaluation of lipase activity in serum by radial enzyme diffusion.
Authors: Goldberg J M , Pagast P 
Published: January 2020

Abstract
Results of determination of serum lipase by radial enzyme diffusion correlate well with those by a titrimetric reference method in the abnormal range. The specificity of the diffusion assay allows the differentiation of patients with pancreatic disease, even when the lipase activity of the serum is within the normal limits of the tritrimetric assay. Pancreatic lipase is not detectable by the diffusion assay in the serum of individuals who are free from pancreatic disease.
Technical pitfalls in measurement of venous plasma NH3 concentration.
Authors: Gerron G G , Ansley J D , Isaacs J W , Kutner M H , Rudman D 
Published: January 2020

Abstract
Measurement of venous plasma NH3 in normal subjects by the ion-exchange method of Forman [Clin. Chem. 10, 497 (1964)] in a hospital clinical laboratory gave a mean value of 640 mug/liter (range, 300-1320 mug/liter; intraassay, intra-individual, and inter-individual coefficients of variation, 8, 47, and 47%, respectively). The following conditions adversely affect the reproducibility of the test: pollution of laboratory atmosphere and glassware by NH3-containing detergents; smoking by patient or analyst; delay, turbulence, or use of heparin lock in venipuncture; delay or warming of plasma above degrees C before mixing it with resin; and delay in colorimetric analysis of resin eluate. When these sources of error were eliminated, the mean value for normals was reduced to 330 mug/liter, the range was narrowed to 220-470 mug/liter, and the above-mentioned CV's were 5, 16, and 17%, respectively. With the precautions cited, furthermore, the intra-assay and intra-individual CV's for fasting NH3 concentration in cirrhotic patients were similarly reduced. An NH3 tolerance test was done by administering a standard dose of NH4Cl to patients and measuring venous plasma NH3 at 0, 15, 30, 60, and 90 min; the NH3 tolerance was quantified from the area under the curve relating concentration to time (mug - min/liter). As measured in the clinical laboratory, NH3 tolerance of cirrhotic patients showed intra-assay and intra-individual CV's of 50 to 90%. When the tolerance tests were repeated in the same subjects with the laboratory precautions listed above, these CV's were reduced to 8-15%.
Analytical toxicology: Applications of element-selective electrolytic conductivity detection for gas chromatography.
Authors: Pape B E 
Published: January 2020

Abstract
We applied a commercially available microelectrolytic conductivity detector to toxicological problems of qualitative and quantitative analysis by gas chromatography. The detector can be used for the sensitive and selective detection of halogen-, nitrogen-, and sulfur-containing compounds. Relative response in different element-selective detector variables such as reaction gas, reaction catalyst, and furnace temperature can be used to further improve qualitative identification by gas chromatography.