bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid-chromatographic determination of urinary riboflavin.
Authors: Gatautis V J , Naito H K 
Published: January 2020

Abstract
We describe a method for determining urinary riboflavin by "high-pressure" liquid chromatography, with fluorometric detection. An aliquot of a 24-h urine specimen is injected directly into the chromatograph and the natural fluorescence of riboflavin is measured as the compound is eluted. Interference from other fluorophores is obviated because of differing retention times. Urinary components other than riboflavin and its analogs or degradation products exhibit no significant fluorescence at the wavelengths used (450 nm excitation, 530 nm emission). Analytical recovery of added riboflavin was 96.5 (SD 1.1)%. The CV within-run was 0.7%, between-run it was 4.3%. Concentrations of riboflavin as low as 10 micrograms/L are readily detected, with a linear relation of response to concentration to at least 2000 micrograms/L.
Colorimetry of diaphorase in commercial preparations and clinical chemical reagents by use of tetrazolium salts.
Authors: Gella F J , Olivella M T , Pegueroles F , Gener J 
Published: January 2020

Abstract
We describe a procedure for assay of diaphorase activity in commercial purified preparations and in clinical chemical reagents by use of iodonitrotetrazolium chloride or other tetrazolium salts. The method is based on measurement of the formazan produced by enzymic reduction of tetrazolium salts in the presence of NADH. The assay procedure has been optimized for linear kinetics, simplicity of operation, nondetectable blank rates, and extended activity/enzyme concentration proportionality. The proposed method has several advantages over the older assay by use of dichlorophenolindophenol.
Glucagon radioimmunoassay with use of antiserum to glucagon C-terminal fragment.
Authors: Nishino T , Kodaira T , Shin S , Imagawa K , Shima K , Kumahara Y , Yanaihara C , Yanaihara N 
Published: January 2020

Abstract
In this pancreatic-glucagon-specific radioimmunoassay we used C-terminal-region-specific antiserum. OAL-123, produced against a 19-29 C-terminal fragment of porcine glucagon. On measurement of pooled plasma the ranges for intra- and inter-assay coefficients of variation were 4.8-8.1% and 7.5-10.7%, respectively. The concentration of immunoreactive glucagon in plasma of healthy subjects, as measured with the OAL-123 assay system, was 87.9 (SD 23.8) ng/L. Measurement of the same plasma samples with the 30K assay system (30K being an antiserum highly specific for pancreatic glucagon) showed a comparable value, 86.2 (SD 26.3) ng/L. We followed changes in human and dog plasma immunoreactive glucagon concentrations on arginine infusion and after glucose load, using the OAL-123 and the 30K assay systems, with identical results. Combining other results of comparative immunochemical characterization of the OAL-123 and 30K assay systems, we confirmed that the antisera raised against the C-terminal fragment of glucagon can be used in radioimmunoassay of pancreatic glucagon.
Specific 125I-radioimmunoassay for cholyglycine, a bile acid, in serum.
Authors: Miller P , Weiss S , Cornell M , Dockery J 
Published: January 2020

Abstract
The concentration of the conjugated bile acid, cholylglycine, in serum is a sensitive and specific indicator of hepatic function. We describe a convenient, specific, and precise radioimmunoassay for cholylglycine, in which 125I-labeled cholylglycyltyrosine is used as tracer. In addition, a blocking agent in the buffer system eliminates binding of bile acids to serum albumin. Therefore no extraction is required. We found no interference by (a) abnormal concentrations of albumin or gamma-globulin, (b) lipemic sera, (c) hemolyzed sera, (d) anticoagulants, or (e) various commonly used drugs. The reference interval for fasting subjects is estimated to be 0.0 to 0.6 mg/L. Our clinical studies show that serum cholylglycine concentrations are usually abnormal in most hepatobiliary diseases, such as viral hepatitis, alcoholic liver disease, cirrhosis, and pediatric liver diseases.
Liquid-chromatographic determination of bilirubin and its conjugates in rat serum and human amniotic fluid.
Authors: Rosenthal P , Blanckaert N , Kabra P M , Thaler M M 
Published: January 2020

Abstract
This newly developed and highly specific and sensitive procedure was applied to the determination of unconjugated bilirubin and its ester conjugates in rat serum and human amniotic fluid. Bilirubin conjugates in biological samples are converted to methyl esters by alkaline methanolysis, extracted into chloroform, and the unconjugated bilirubin and esterified pigment derivatives are fractionated by "high-performance" liquid chromatography. The separated pigments are measured spectrophotometrically. Bilirubin and its mono- and di-conjugates are readily quantitated, even in previously undetectable concentrations. Linearity was established from 0.07 to 121.2 mumol/L for unconjugated bilirubin, 0.07 to 34.6 mumol/L for the C-8 monoconjugate, 0.06 to 69.3 mumol/L for the C-12 monoconjugate, and 0.17 to 43.7 mumol/L for the di-conjugate fraction. The detection limit was 0.03 mumol/L for unconjugated bilirubin and for each monoconjugate, and 0.1 mumol/L for the di-conjugated pigment.
Effect of feedback to clinical staff of information on clinical biochemistry requesting patterns.
Authors: Grivell A R , Forgie H J , Fraser C G , Berry M N 
Published: January 2020

Abstract
Attempting to reduce the number of unnecessary tests requested, we initiated a program providing continuous feedback to clinicians concerning their requesting patterns of clinical biochemistry laboratory tests. At four-week intervals each medical specialist received data showing the number and costs of tests requested by all members of his team, the number of patients who had tests, and various related information. Comparative summaries, in frequency-histogram format, of the number of specimens submitted and the costs involved allowed each medical specialist to rate his own performance against that of his peers. The program appeared to have no effect on laboratory use, although reliable information concerning workload patterns was accrued. The degree of education of medical students in clinical biochemistry did not appear to influence the use they made of the laboratory after qualification. The specimens per bed-day ratio is suggested as a useful parameter in the identification of inappropriate laboratory use and as a standard parameter for comparing laboratory use in different hospitals.
Clinical applicability of acid phosphatase isoenzyme assay.
Authors: Sun T , Lam K W , Narukar L 
Published: January 2020

Abstract
We compared electrophoretic evaluation of acid phosphatase isoenzymes with spectrophotometric determination of prostatic acid phosphatase in terms of clinical utility. In all of 33 cases of prostatic carcinoma, an increased prostatic fraction was detected; in nine prostatectomized patients, this fraction returned to normal as measured by either technique. Abnormal spectrophotometric results were also seen in 10 cases of benign prostatic hypertrophy and seven cases of non-prostatic disorders, but only two benign prostatic hypertrophy and one non-prostatic case showed a prostatic band (band 2) in an electrophoretogram. Band 2 was not demonstrated in 463 patients affected by a great variety of diseases but without prostatic disorders. A weak band 5 was seen in patterns for most patients, except for cases with metastatic bone tumor and Gaucher's disease, whose serum showed a strong band 5. The specificity of bands 2 and 5 seems to be confirmed by this large series of patients. Measurement of acid phosphatase isoenzymes is recommended as a routine screening test for patients whose serum acid phosphatase is abnormally high, because the isoenzyme study not only indicates the presence or absence of prostatic cancer but also whether or not there is bony metastasis. Other disorders such as Gaucher's disease, different kinds of leukemias, and thrombocythemia may also be detected and distinguished by this screening technique.
Total surface-active phospholipid/sphingomyelin ratio as an index of fetal lung maturity.
Authors: Dohnal J C , Bowie L J 
Published: January 2020

Abstract
As an index of fetal lung maturity, the ratio of total surface-active phospholipid (phosphatidylethanolamine + phosphatidylinositol + phosphatidyglycerol + lecithin) to sphingomyelin performs as well as or better than any other indicator that we tested, showing 92% sensitivity and 98% specificity. The sensitivity and specificity, respectively, of the other methods were: (a) lecithin/sphingomyelin ratio, 92% and 95%; (b) alkaline phosphatase/glutamyltransferase ratio, 100% and 49%; (c) microviscosity, 75% and 97%; and (d) adsorbance at 650 nm, 50% and 73%. The procedure requires 2 h or less and its simplicity allows it to be offered on a 24 h/day basis without necessitating special training.
Method for testing antiserum titer and avidity in nephelometric systems.
Authors: Hudson G A , Ritchie R F , Haddow J E 
Published: January 2020

Abstract
Antiserum performance in a nephelometric system can be characterized by parameters derived from measuring reaction rates. The characterization process is derived from a series of dose-response curves (elicited nephelometric response vs antigen concentration) generated from various dilutions of the antiserum being tested. Antiserum titer can then be calculated by plotting the antigen concentration found at one-half the maximum nephelometric response (Hmax) of each dose-response curve (C50) vs the corresponding antiserum dilution. Antiserum avidity can be calculated by plotting Hmax against its corresponding antiserum concentration. After general expressions are determined for C50 and Hmax vs antiserum concentration, a single dose-response curve suffices for characterizing antisera with respect to titer and avidity. Direct evidence is provided for the validity of C50 and Hmax as measures of titer and avidity by correlating these parameters with antiserum binding strength and with the number of antibodies eluted from immobilized antigen. This method can be applied to evaluate and compare different antiserum lots having the same specificity, to identify reagent inadequacies by comparing antisera of different specificity, and to predict the optimal antiserum dilution to use in performing an assay.
Distribution of enzymes in dog heart and liver; significance for assessment of tissue damage from data on plasma enzyme activities.
Authors: Visser M P , Krill M T , Muijtjens A M , Willems G M , Hermens W T 
Published: January 2020

Abstract
When organ damage is assessed from activities of tissue enzymes in plasma, it is assumed that variations in tissue enzyme content, both among individuals and between different sites within an organ, are small. We checked these assumptions, using canine heart and liver. We determined creatine kinase (CK; EC 2.7.3.2), lactate dehydrogenase (LD; EC 1.1.1.27), aspartate aminotransferase (AST; EC 2.6.1.1), and glucosephosphate isomerase (GPI; EC 5.3.1.9) in different sites of different hearts; the results showed CVs of 9.3, 9.1, 13.5, and 8.2%, respectively. A small transmural gradient in CK is found in the left ventricle. Determination of AST, GPI, and alanine aminotransferase (ALT; EC 2.6.1.2) in different sites of different livers gave CVs of 12.5, 17.0, and 11.6%, respectively. Most of the total variation is interindividual. The unreliability of early data and conflicting reports on transmural myocardial enzyme gradients are discussed. We conclude that by use of proper enzymes, such as LD for the heart and ALT for the liver, organ damage can be estimated, although there are inherent problems in relating enzyme release to loss of tissue mass.
Equations and nomogram for the relationship of human blood p50 to 2,3-diphosphoglycerate, CO2, and H+.
Authors: Samaja M , Mosca A , Luzzana M , Rossi-Bernardi L , Winslow R M 
Published: January 2020

Abstract
We describe a new method for tonometry of small amounts of blood (up to 0.25 mL) at known pO2, PCO2, and temperature, in small, reusable, closed Pyrex flasks. Equilibrated blood is analyzed for oxygen saturation, pH, and organic phosphate concentration with standard techniques, and its p50 (the pO2 at which hemoglobin is half-saturated with oxygen) is determined with full control of all the variables known to affect it. The SD in the measurement of p50 is 0.044 kPa (0.33 mmHg). We made 63 determinations of p50 on normal human blood under different conditions of pH and pCO2, and with different concentrations of 2,3-diphosphoglycerate and ATP. Empirical equations and a nomogram were derived, which allow the calculation of p50 from known values of pCO2, pH, and [2,3-DPG]/[Hb4] molar ratio with a SD of 97 and 114 Pa (0.73 and 0.86 mmHg), respectively.
Continuous-flow enzymic determination of creatine in urine.
Authors: Yasuhara M , Fujita S , Furukawa I , Arisue K , Kohda K , Hayashi C 
Published: January 2020

Abstract
A new enzymic method is described for the determination of creatine in urine by continuous-flow analysis. The measurement is accomplished by transforming creatine to formaldehyde in reactions catalyzed by creatinase (creatine amidinohydrolase) and sarcosine dehydrogenase. The formaldehyde is reacted with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole to form a purple product, which is measured colorimetrically. The method gives a linear standard curve for creatine concentrations up to 100 mg/L. Precision and analytical recovery are excellent, and results correlate well with those by the more-difficult Folin method, which currently is most often used for this analysis.
Bratton-Marshall and liquid-chromatographic methods compared for determination of sulfamethazine acetylator status.
Authors: Whelpton R , Watkins G , Curry S H 
Published: January 2020

Abstract
Synthesis of acetylsulfamethazine has made possible an evaluation of the Bratton-Marshall assay for this compound. Hydrolysis is an essential step in the assay, which depends on color development with the sulfamethazine formed in the hydrolysis. Sulfamethazine decomposes under the conditions needed for hydrolysis of acetylsulfamethazine, and this leads to depressed values for acetylsulfamethazine and to low figures for clinical "percent acetylation." Because of this, a simple "high-pressure" liquid-chromatographic procedure was developed for the assay; it requires no hydrolysis, is rapid in application, and can be applied to as little as 10 microL of capillary blood obtained by finger-to-puncture. We found that the cutoff point between "slow" and "fast" acetylators, when this method was used on samples from 75 subjects collected about 6 h after dosage, was 40% "acetylation" in plasma.
Automated analysis for plasma epinephrine and norepinephrine by liquid chromatography, including a sample cleanup procedure.
Authors: Yamatodani A , Wada H 
Published: January 2020

Abstract
We describe a fully automated method of analysis for plasma epinephrine and norepinephrine by use of a two-column system of "high-performance" liquid chromatography. Catecholamines in deproteinized plasma are purified on the first (preparation) column, then transferred automatically to the second (analytical) column in which epinephrine and norepinephrine are resolved. These compounds are then determined fluorometrically with a continuous-flow reaction system by the trihydroxyindole method. The minimum sensitivity of the method is 0.02 and 0.04 pmol for epinephrine and norepinephrine, respectively. One assay can be completed in 30 min, and greater than 1 mL of plasma is required for the procedure. The within-run CV in the chromatographic determination of pooled plasma was greater than 3%, and the analytical overall recovery of the two compounds was 95%. The concentrations in plasma of medical students at rest were 0.32 (SE 0.06) nmol/L for epinephrine and 0.98 (SE 0.08) nmol/L for norepinephrine.
Improved method for quantitative determination in serum of alkaline phosphatase of skeletal origin.
Authors: Farley J R , Chesnut C H , Baylink D J 
Published: January 2020

Abstract
In this quantitative method for detection of skeletal alkaline phosphatase (EC 3.1.3.1) activity in human serum, intestinal and placental alkaline phosphatase activities are recognized by their susceptibility to inhibition by L-phenylalanine, and skeletal and hepatic alkaline phosphatases are distinguished by their different sensitivities to inactivation by heat. Alkaline phosphatase isoenzymes prepared from organ sources may behave differently from the corresponding isoenzymes in serum. Our procedure allows us to include organ-derived internal standards of skeletal, intestinal, and biliary alkaline phosphatase to minimize between-assay variation. In preliminary applications, we have found that (a) total serum alkaline phosphatase activity is extremely variable in post-menopausal osteoporotic subjects and is not a reliable index of skeletal alkaline phosphatase activity; (b) seven osteoporotic patients responding to therapy with sodium fluoride with increased bone formation showed increased skeletal alkaline phosphatase activity in their serum as compared with age-matched controls (p less than 0.005); and (c) 10 post-menopausal osteoporotic patients responding to therapy with stanozolol with increased total body calcium showed an increase in circulating skeletal alkaline phosphatase activity (p less than 0.001).
Detection of aspartylglycosaminuria by gas--liquid chromatography.
Authors: Maury C P 
Published: January 2020

Abstract
I describe a rapid gas-chromatographic method for specific detection of the lysosomal storage disease aspartylglycosaminuria, based on the identification of the major storage compound, 2-acetamido-1-N-(4'-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (GlcNAc-Asn) in the urine of affected individuals. A 50-microL sample of urine is methylated without prior purification; the methylation products are then analyzed by gas--liquid chromatography. Under these conditions a diagnostic GlcNAc-Asn peak can be seen in the urine of patients with aspartylglycosaminuria, but not in the urine of control subjects or patients with related storage diseases.
Urinary free catecholamines determined by liquid chromatography--fluorometry.
Authors: Anderson G M , Young J G , Jatlow P I , Cohen D J 
Published: January 2020

Abstract
Free norepinephrine, epinephrine, and dopamine are determined in urine after purification on a small ion-exchange column and concentration on alumina. The catecholamines are separated by reversed-phase ion-pair chromatography and are quantitated by measuring their native fluorescence (lambda ex 285 nm, lambda em 305 nm). The internal standard is dihydroxybenzylamine. Within-day CVs for the compounds ranged from 1.6 to 5.6%; between-day CVs were 6.6 to 9.8%.
Effects of temperature on the steady-state kinetics and measurement of aspartate aminotransferases.
Authors: Rej R , Vanderlinde R E 
Published: January 2020

Abstract
We examined the effects of temperature on the activity and steady-state kinetics of aspartate aminotransferase (EC 2.6.1.1), using purified human soluble (s-AspAT) and mitochondrial (m-AspAT) isoenzymes, human serum, and porcine s-AspAT. All enzymes obeyed similar linear Arrhenius relationships over the range 20-40 degrees C. Apparent energies of activation (52.3 kJ.mol-1) and ratios of activity between 30 and 37 degrees C (0.626) were identical for the human s- and m-AspAT. This ratio was 0.623 (SEM 0.004) for human sera; deviation from the predicted ratio by individual sera was within analytical error. Similar activity/temperature relationships were observed for porcine s-AspAT. The use of factors to convert AspAT activities at 30 and 37 degrees C influenced neither precision of measurement of frequency distributions of results. The apparent Michaelis constants for the human isoenzymes increased with temperature. The least-influenced Km was for 2-oxoglutarate and s-AspAT: K2-oxoglutarate was 0.24 mmol.L-1 at 25 degrees C and 0.29 mmol.L-1 at 37 degrees C; apparent enthalpy change for substrate binding (delta HS) was 12.1 kJ.mol-1. The largest variation was for 2-oxoglutarate and m-AspAT: K2-oxoglutarate was 0.46 mmol.L-1 at 25 degrees C and 1.02 mmol.L-1 at 37 degrees C; delta HS was 50.8 kJ.mol-1. Incubation of the human isoenzymes with substrate mixture (without 2-oxoglutarate) at 23 and 37 degrees C did not affect activity during 60 min if tris(hydroxymethyl)aminomethane buffer was used. When the isoenzymes were diluted to 10 nmol-L-1 (about 200 U.L-1) in buffer alone and incubated at 50 degrees C, m-AspAT activity was decreased by 20% after 120 min; the cytoplasmic enzyme was unaffected.
Isolation and purification of aspartate aminotransferase isoenzymes from human liver by chromatography and isoelectric focusing.
Authors: Leung F Y , Henderson A R 
Published: January 2020

Abstract
To purify cytoplasmic and mitochondrial isoenzymes of aspartate aminotransferase (EC 2.6.1.1) from human liver. We used heat treatment, ammonium sulfate precipitation, anion- and cation-exchange chromatography, affinity chromatography, and isoelectric focusing. Final preparations of the isoenzymes were homogeneous, with specific activities of 198 and 208 kU/g for the cytoplasmic and the mitochondrial enzymes, respectively. The mitochondrial isoenzyme focused as a single band with a pl value of 9.60, whereas the cytoplasmic isoenzyme had subforms with pl values of 5.22, 5.42, and 5.62 at 4 degrees C. In Tris . HCl buffer, both isoenzymes have an activity maximum at pH 7.8. In [bis(2-hydroxyethyl)amino]tris(hydroxymethyl)methane (Bistris) buffer, however, the mitochondrial isoenzyme also showed an optimum pH of 6.7.
Simple laboratory determination of excess oligosacchariduria.
Authors: Sewell A C 
Published: January 2020

Abstract
I describe a simple set of procedures for the screening of patients' urine to detect oligosaccharide-storage diseases. Urines from patients with mucolipidosis I, mannosidosis, fucosidosis, aspartylglycosaminuria, and type VI glycogen-storage disease can be distinguished by thin-layer chromatography. Patients with beta-galactosidase deficiency can be detected by use of a combination of ion-exchange and thin-layer chromatography. Excess sialyloligosaccharide excretion is detected by using gel filtration and a quantitative assay for neuraminic acid. The advantages of the system are detection of virtually all known disorders in which oligosaccharides are over-excreted, production of characteristic patterns, and small sample requirement.
Quantification of damage to striated muscle after normothermic or hypothermic ischemia.
Authors: Presta M , Ragnotti G 
Published: January 2020

Abstract
Muscular ischemia of different duration was induced by use of a tourniquet applied to the rear left leg of rabbits under normothermic or hypothermic conditions, and variations in serum creatine kinase, lactate dehydrogenase, K+, Ca2+, and lactate were determined at various intervals after blood flow was restored. A monocompartmental model analysis applied to the activities of the two enzymes in the serum demonstrated that: (a) the total enzyme activity leaked into the blood is proportional to the duration of normothermic but not of hypothermic ischemia; (b) this enzyme leakage persists until at least the third day after blood flow is restored; (c) a substantial part of the ischemic damage seems to occur as a consequence of re-perfusion, not of the ischemia itself; and (d) hypothermia greatly minimizes the ischemic damage. The data we obtained for K+ and for lactate confirm the protective effect of hypothermia.