bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison of Reduced-NAD Preparations from Four Commercial Sources
Authors: McComb R B , Gay Royal J 
Published: January 2020

Abstract
The physical and chemical properties of several commercial sources of reduced NAD were examined. Properties compared included physical appearance, sodium and phosphorus content, ultraviolet light absorption at 260 and 340 nm, and relative rates of oxidation with two human LDH isoenzymes. Major differences between individual preparations were noted with respect to physical and chemical properties, as well as in the activity measurements. The commercial reduced-NAD preparations most rapidly oxidized by LDH were white, free-flowing substances with 260 nm:340 nm absorbance (A260:A340) ratios below 2.45. Detectable amounts of an LDH inhibitor were found in all preparations examined. A strong LDH inhibitor, which had the same properties as the inhibitor present in commercial reduced NAD, was isolated by column chromatography. This LDH inhibitor was found to produce the same degree of inhibition toward four LDH isoenzymes.
Photoelectric Determination of Plasma Clotting Times
Authors: Mortensen Esper 
Published: January 2020

Abstract
A photoelectric clot timer is described. The apparatus allows a large analytic capacity, with good precision and correlation to manual methods, and can be used with capillary blood. Prothrombin analysis according to the method of Quick and Owren, the Thrombotest* method, and determinations of partial thromboplastin time are applicable to the apparatus. The semiautomated procedure is extremely simple, and the results are independent of the technicians performing the test.
Rapid Gas Chromatographic Assay for Pregnanolone in Pregnancy Urine
Authors: Metcalf Mary G 
Published: January 2020

Abstract
In 3.8 N HCl at 100°, pregnanediol is selectively destroyed in the presence of pregnanolone, and urinary pregnanolone hydrolysis is complete within 5 min. A rapid gas chromatographic assay for pregnanolone in pregnancy urine is described. As many as 30 samples may be prepared for injection in 1.5 hr. Four women in the third trimester of normal pregnancy excreted 10-29 mg. of pregnanolone per 24 hr.
A Simplified Method for the Determination of Pepsinogen in Blood and Urine
Authors: Uete Tetsuo , Wasa Michiko , Shimogami Akemi 
Published: January 2020

Abstract
A simplified method for the determination of pepsinogen in blood and urine has been developed using serum protein as substrate. As crystalline pepsin digests human serum protein optimally in the region of pH 2, and blood exhibits such proteolytic activity on its own serum protein in this region, the determination of pepsinogen in blood is performed at this pH. The proteolytic activity of serum or plasma on its own (autologous) serum protein is inactivated by alkalinization. The blood of gastrectomized patients showed extremely low proteolytic activity in the region of pH 2 by the present method, indicating an absence of pepsinogen. The present method has greater specificity and accuracy than the method employing either hemoglobin or casein as substrate.
Automatic Determination of Lactic Acid in Blood
Authors: Hadjiioannou T P , Siskos P A , Valkana C G 
Published: January 2020

Abstract
An automatic reaction rate method is described for the determination of lactic acid in blood. The L(+)-lactic acid is selectively oxidized in the presence of lactic dehydrogenase and diphosphopyridine nucleotide to form an absorbing species. The time required for the formation of a fixed amount of DANH is measured automatically and related directly to the lactic acid concentration. The method is sensitive, more rapid than purely chemical procedures, and relative errors are only about 1-3% for the range 6-200 µg of lactic acid. The coefficient of variation for the determination of lactic acid in 0.2 ml of blood is 3%. Measurement times vary from a few seconds to about 2 min.
Measurement of Bisulfite in Biologic Solutions
Authors: Wilkins James W , Rivecca James N 
Published: January 2020

Abstract
In order to evaluate the toxicity of sodium bisulfite (NaHSO3) used in peritoneal dialysis solutions it was necessary to measure bisulfite in simple solutions and serum. A microdiffusion technic is described for quantification of bisulfite. This involves evolution of SO2 gas from bisulfite by acidification, trapping it as H2SO3, oxidation of the H2SO3 to H2SO4 by hydrogen peroxide, and titration of the hydrogen ion with dilute base. The method is easily performed and is quantitative in the range of 50-500 µg bisulfite per milliliter in simple solutions. Studies in serum show incomplete yet quantitatively reproducible recovery.
Comparison of Improved Fluorometric Methods Used to Quantitate Plasma Catecholamines
Authors: Manger William M , Steinsland O S , Nahas G G , Wakim Khalil G , Dufton S 
Published: January 2020

Abstract
Comparative studies reveal that the ethylenediamine and the trihydroxyindole method when employed as suggested are suitable for assessing sympatho-adrenal activation under various stressful conditions that are accompanied by release of catecholamines into the circulation. Both methods are very accurate in quantitating epinephrine or norepinephrine that has been added to plasma or whole blood, although recovery from blood is less, owing mainly to some association of catecholamines with formed elements, primarily erythrocytes. Use of sodium thiosulfate in the ethylenediamine procedure minimizes association of catecholamines with formed elements. If blood samples are cooled in ice water when collected, association of catecholamines with blood cells can be further reduced. In the trihydroxyindole method, unless tubes containing blood samples are immediately immersed in ice water, a significant amount of catecholamines will disappear from plasma, because of this association of catecholamines with cells.
Determination of Urinary Formaldehyde Following Administration of Methenamine Salts
Authors: Greenfield W , Berg R , Moore R 
Published: January 2020

Abstract
Earlier studies on formaldehyde determination in the urine of subjects receiving methenamine salts have given questionable results. A modification of the Tannenbaum and Bricker procedure was utilized to evaluate formaldehyde production from 3 methenamine salts and methenamine base. Formaldehyde production was studied in vitro and in vivo.
Chemical Composition of Peripheral Nerves
Authors: Anghinah Abrao , De Jorge Francisco Bastos , Aisen Julinho 
Published: January 2020

Abstract
The present paper presents normal values for the contents of water, sodium, potassium, calcium, magnesium, phosphorus, chloride, copper, and iron in peripheral nerves (tibialis, fibularis profundus, and ulnaris) in individuals without any neurological condition. This study constitutes a basis for the interpretation of other data, still being gathered, relating these normal values with those obtained for peripheral nerves under pathological conditions.
Automated Fluorometry as Applied to the Assay of Individual Estrogens in Purified Urinary Extracts
Authors: Strickler Herbert S , Stanchak Patricia J 
Published: January 2020

Abstract
Using the Kober-lttrich fluorescence procedure, automated fluorometry was applied to the assay of individual estrogens and their 3-methyl ether derivatives in the purified urinary extracts of nonpregnant women. The values obtained by using this new automated scheme were compared with those obtained by the manual time-decay modification of the Slaunwhite-Engel fluorescence method; the comparison shows excellent correlation. A ratio of the corrected peak reading at 546 mµ. excitation to the corrected peak reading at 490 mµ. excitation was used not only to follow the effect of introducing additional purification stages in the development of assay procedures, but also to follow impurity levels in sample analyses. The same assembly of modules can be used for samples dissolved in acidified water, 70% methanol, and, with a simple change of manifold, in 1 N sodium hydroxide. This fully automated assay provides precise conditions in all stages.
A Colorimetric Method for the Determination of Serum Arginase Activity
Authors: Loeb Walter F , Stuhlman Robert A 
Published: January 2020

Abstract
A detailed description of a method for the determination of serum arginase activity is presented. Arginase activity is demonstrated by the decrease in arginine concentration in a reaction mixture, as determined by a modification of the method of Sakaguchi. The reaction is linear until inhibited by the increasing concentration of ornithine. The cellular distribution of arginase is reviewed to determine its role in diagnosis and in the evaluation of biologic systems.
Simultaneous Determination of Urinary Estriol, Pregnanediol, and Pregnanolone by Gas-Liquid Chromatography
Authors: Baynton Robert D , Campbell Donald J 
Published: January 2020

Abstract
A simplified method for following the urinary excretion of estriol, pregnanediol, and pregnanolone during the course of pregnancy is presented. The procedure has been used successfully in a large hospital laboratory. An important advantage is that the estrogen and progesterone metabolites are measured simultaneously, and separate extraction and gas-liquid chromatography is not required. The urine specimen is hydrolyzed enzymatically, extracted, and the steroids are converted to trimethylsilyl ethers. Temperature-programmed gas-liquid chromatography is carried out on a 2% neopentyl glycol succinate column using a hydrogen flame ionization detector.
Thyroxine-Binding Prealbumin in Thyrotoxicosis and Hypothyroidism
Authors: Vergani C , Stabilini R , Agostoni A 
Published: January 2020

Abstract
The serum concentrations of thyroxine-binding prealbumin (TBPA) have been determined quantitatively by an immunochemical method in patients with thyrotoxicosis and hypothyroidism. Low levels of TBPA were found in all patients with untreated thyrotoxicosis. Normal values were found in 8 of 10 cases of untreated hypothyroidism.
Comparison of Dumas and Kjeldahl Methods for Determination of Nitrogen in Feces
Authors: Stitcher Joseph E , Jolliff Carl R , Hill Robert M 
Published: January 2020

Abstract
The present study was undertaken to compare the nitrogen content of human feces as determined by the Kjeldahl technic and the micro-Dumas method as utilized in the automated Coleman nitrogen analyzer. The standard deviation between duplicate determinations of the same sample was 0.06% nitrogen in the case of the nitrogen analyzer and 0.02% nitrogen for the Kjeldahl method. The standard deviation between the average values obtained by each method for each sample was 0.07% nitrogen. The agreement between the two methods seemed to be independent of the nitrogen content. The apparent recovery of nitrogen by the nitrogen analyzer was found to be greater than that recovered by the Kjeldahl procedure. Factors which may be involved in this difference in recovery between the two methods are discussed.
Simultaneous Spectrophotometric Determination of Diphenylhydantoin and Phenobarbital in Biologic Specimens
Authors: Wallace Jack E 
Published: January 2020

Abstract
A rapid, accurate method for determining diphenylhydantoin and phenobarbital in a single biologic sample is described. Separation of the two drugs after their initial chloroform extraction from the specimen is not required. After extraction, diphenylhydantoin is converted to benzophenone by pemanganate oxidation. Phenobarbital is determined by differential absorption between pH values of 12.0 and 10.5. Final quantitation in each case is carried out by ultraviolet spectrophotometry. Barbiturates do not interfere with the diphenylhydantoin analysis or vice versa. The method is sensitive enough for detecting subtherapeutic amounts of each compound with a high degree of specificity.
Aldolase
Authors: Pinto Patrick V C , Kaplan Alex , Van Dreal Paul A 
Published: January 2020

Abstract
Two commercial kits for the measurement of serum aldolase activity by a spectrophotometric (UV) method were evaluated. Neither was satisfactory in their present forms, since aldolase activity was not rate-limiting in one, and side reactions utilizing NADH occurred in the other.
A study was made of the optimum concentrations of substrate, NADH, buffer, and coupled enzymes (triosephosphate isomerase and α-glycerophosphate dehydrogenase) in the procedure utilized by one kit, and a method based upon these findings is proposed. The key feature of the proposed method is an increase in the amount of the auxiliary enzymes, GDH/TIM, so that aldolase becomes the rate-limiting enzyme. The proposed method also differs from the kit procedure in the concentrations of substrate and NADH, in the choice of buffer, volume of reaction mixture, and in the order of adding solutions to the reaction mixture.
A Simple and Rapid Procedure for the Determination of α Amino-nitrogen and Ammonia in Urine
Authors: Clarkson T W , Ferraio L 
Published: January 2020

Abstract
The ninhydrin-colorimetric procedure for the determination of urinary α amino-nitrogen has been simplified by the use of the Conway microdiffusion unit to remove ammonia from the sample. In this way, urinary ammonia is measured, and at the same time an ammonia-free urine sample is ready for α amino-nitrogen analysis. Values for total and free α amino-nitrogen in normal urine samples were found to be similar to those previously reported by more complicated procedures.
Automated Determination of Free Amino Groups in Serum and Plasma Using 2,4,6-Trinitrobenzene Sulfonate
Authors: Palmer D W , Peters T 
Published: January 2020

Abstract
A simple automated method is described for determining the level of total free amino acids in the blood. The method utilizes the AutoAnalyzer, and is based on the formation of colored complexes by uniting free amino groups with 2,4,6-trinitrobenzene sulfonate (TNBS). Proteins do not interfere because the free amino acids are first separated by dialysis. Characteristics of the reaction and potential clinical applications of the procedure are discussed.
Ammonium Sulfate Precipitation of Conjugated Estrogens in Pregnancy Urine: Rapid Assay and Glucose Effects
Authors: Pinkus Geraldine S , Pinkus Jack L 
Published: January 2020

Abstract
Ammonium sulfate precipitation of total estrogens in pregnancy urine effectively removes many substances that interfere with estrogen assays. From systematic study of the precipitation technique we define optimum conditions for isolating free and conjugated estrogens. Solutions of the precipitated estrogens are directly analyzed. Glucose effects on these assays are negligible. Urinary estrogens are minimally exposed to acid or alkali before analysis by the Ittrich procedure, thus protecting the labile fraction that may be significant in complicated pregnancies
Automated Enzymatic Method for L-Lactate in Blood
Authors: Mann George V , Shute Elizabeth 
Published: January 2020

Abstract
An automated method for measuring L-lactic acid in whole blood is de-scribed. The method uses a Somogyi procedure for deproteinizing and stabilizing the sample, the lactic dehydrogenase derived from yeast coupled with potassium ferricyanide for the determination. Results by this method compare favorably with those obtained by manual and automated procedures in which lactic dehydrogenase from muscle is used
An Automated System for Kinetic Multiple-Point Determinations Exemplified by Serum Lactic Dehydrogenase Determination
Authors: Fasce Charles F , Rej Robert 
Published: January 2020

Abstract
A fully automated procedure is presented for kinetic determinations and for use of the AutoAnalyzer in their study; serum lactic dehydrogenase has been used to illustrate such an application. The LDH-catalyzed oxidation of L-lactate by NAD in separate, unequal time-delay coils is determined by measuring the natural fluorescence of reduced coenzyme. The normal range for LDH activity by this method was 63-169 U/liter at 37°C.
Calculation of Normal Ranges by Methods Used for Resolution of Overlapping Gaussian Distributions
Authors: Gindler E Melvin 
Published: January 2020

Abstract
Distribution of a quantity, e.g., concentration of a serum constituent, in a typical general hospital population is considered. It is assumed that the distribution within any subpopulation is Gaussian and that adjacent subpopulations overlap somewhat, presenting overlapping Gaussian distributions. Bhattacharya’s procedure for resolving such overlapping distributions, based upon differentiation of the Gaussian distribution equation, is applied to the determination of the apparent normal range as well as, in some cases, an abnormal range. Gaussian probability paper is used for estimating the normal range and the conditions discussed under which this method may be expected to give a valid estimate. Use of the chi-square test to evaluate the long-term constancy of clinical laboratory data distribution, normal and abnormal, is also considered.
Simplified Procedure for Determination of Estrogen in Pregnancy Urine
Authors: Grannis George F , Dickey Richard P 
Published: January 2020

Abstract
Determination of total estrogen in pregnancy urine has involved hydrolysis, extraction of estrogen, development of color, and extraction of chromogen prior to absorbance measurements. The necessity for each of these steps was evaluated and a more simple procedure was developed which requires only extraction of estrogen and development of color. The new procedure should be useful for prenatal screening and monitoring of high-risk pregnancies.
Development of Normal Values for Use in Multitest Biochemical Screening of Sera
Authors: O’Kell Richard T , Elliott Joseph R 
Published: January 2020

Abstract
Age- and sex-related "normal" values were calculated for data obtained by screening 8015 patients’ sera with the Technicon SMA 12/60 at the time of hospital admission. Calcium, phosphorus, total protein, and albumin concentrations decrease with age; glucose, urea nitrogen, cholesterol, and lactic dehydrogenase concentrations increase. Uric acid concentration increases with age in women. Mean values for calcium, glucose, urea nitrogen, and uric acid concentrations are greater in men. Serum glutamic-oxaloacetic acid transaminase activity is most frequently abnormal, total protein concentration least frequently. Alkaline phosphatase and bilirubin results were unremarkable.
Improved Accuracy in Automated Fluorometric Determination of Plasma Triglycerides
Authors: Noble Robert P , Campbell Frank M 
Published: January 2020

Abstract
Accuracy of the automated fluorometric measurement of triglyceride by the technique of Kessler and Lederer is limited by the instability of the baseline. Concentration of the alcoholic KOH reagent was modified, and the pump tube manifold altered to provide on-stream mixing of the KOH reagent, which overcame this difficulty. A relatively inexpensive fluorometer with the solid-state photomultiplier microphotometer, modified to provide dual-scale sensitivity, was used to increase precision of measurements. Analytical results for 30 serum samples, taken from three pools of frozen serum, show the accuracy of the measurements to be ±8 mg/100 ml and the standard deviation ±9 mg/100 ml for a single determination.
Problem of the Unit of Reference in Expressing Biomedical Data
Authors: Barak Anthony J 
Published: January 2020

Abstract
This paper reviews various bases used by investigators in the biomedical field for expressing analytical data obtained from biological tissues. The advantages of certain units of reference in certain research situations and the pitfalls of other modes of expression are discussed. I suggest that authors express their data using several bases when no particular one is fully adequate. Use of wet weight, DNA, and total protein (as polypeptide) as bases would add new dimensions to the data and may suggest new possibilities for further experimental investigation.
Comparison of the Weber-Schalm Method with the Ducci-Watson Modification of the Malloy-Evelyn Method for Serum Bilirubin Determination
Authors: Perrelli W Vincent , Watson C J 
Published: January 2020

Abstract
Unconjugated bilirubin, conjugated bilirubin, and mixtures of various proportions of each were dissolved in depigmented human serum. These, together with normal and pathologic native human sera, were analyzed for conjugated, unconjugated, and total bilirubin by the Weber-Schalm method. Results were compared with the determination of "prompt direct reacting bilirubin" and of total bilirubin by the Ducci-Watson modification of the Malloy-Evelyn method. Comparisons show that the Weber-Schalm method more accurately measures conjugated bilirubin concentrations in serum in which the bilirubin is mostly conjugated, but that it gives falsely high values for unconjugated bilirubin in serum in which more of the bilirubin is in the unconjugated form. The two methods gave statistically identical total bilirubin values for the native serum tested. A method is described for correcting the unduly low values for prompt, direct reacting bilirubin in terms of percentage of conjugated bilirubin.
An Improved Reagent System for the Measurement of Serum Uric Acid
Authors: Jung D H , Parekh A C 
Published: January 2020

Abstract
The reagent is modified as follows: Serum chromogens are destroyed by trisodium phosphate. The use of phosphotungstic acid eliminates the tungstate and sulfate anions, a frequent cause of turbidity. Triethanolamine, added to the carbonate—urea mixture, provides unusual stability of the color through its buffering action. Only 0.2 ml of serum is required. The method is highly reproducible and accurate; analytical results agree closely with those obtained by the uricase or cyanide—urea method.
An Improved Method for Preparation of Feces for Bomb Calorimetry
Authors: Lovelady Hubert G , Stork Emmett J 
Published: January 2020

Abstract
As a preliminary to bomb calorimetry, weighed, homogenized fecal slurries are prefrozen and lyophilized. Advantages of this method over the method of drying in a vacuum oven include: more moisture is removed from the sample initially, drying time is reduced from 48 h to 16 h, grinding is eliminated and objectionable odors are eliminated during sample processing.
A New Saccharogenic Micromethod for Measurement of Amylase Activity in Biological Fluids
Authors: Lorentz Klaus , Oltmanns Detlef 
Published: January 2020

Abstract
To determine serum amylase activity we have quantitatively measured the glucose and maltose hydrolyzed from soluble starch by colorimetrically measuring the reduction of colorless triphenyltetrazolium chloride to a red formazan, which is dissolved in methanol. The method is suitable for use with microsamples of all biological fluids, and is specific for the final products of starch digestion. Values found for sera from 55 apparently healthy blood donors ranged from 0.15 to 1.55 (mean, 0.83; standard deviation, ±0.4) mg of glucose per ml per h, corresponding to 7.5 to 78 Somogyi units.