bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acetate intolerance and an inhibitor of acetate utilization in hemodialysis patients.
Authors: Egan J D , Wells I C 
Published: January 2020

Abstract
Diminished ability to utilize acetate (acetate intolerance) developed in a male patient on chronic hemodialysis after five years of maintenance dialysis. His ability to utilize lactate was also subnormal. We studied acetate metabolism in vitro by isolating lymphocytes from the patient's blood before dialysis and measuring their ability to convert [1-14C]acetate to 14CO2. His cells metabolized acetate only 35% as well as did lymphocytes from normal adults. The inhibition appeared when the patient's lymphocytes were cultured, and the ability of normal lymphocytes to oxidize acetate decreased after they had been incubated in the patient's plasma. We conclude that an inhibitor of acetate utilization is present in the plasma and in (or on) the cells of this acetate-intolerant patient. The diminished ability of the patient to utilize lactate and the presence of normal concentrations of pyruvate, citrate, and ketone bodies in his blood suggest that the inhibitor functions at the cell surface to impede the entrance of acetate into the cells. The inhibitor appears to be dialyzable; its nature is unknown. Its accumulation in the plasma of chronic hemodialysis patients has not been thus far associated with any deleterious effects other than prolonging the metabolic acidosis of such patients.
Liquid chromatographic analysis of disopyramide and its mono-N-dealkylated metabolite.
Authors: Lima J J 
Published: January 2020

Abstract
We describe a rapid, sensitive, and specific "high performance" liquid chromatographic analysis for disopyramide and its mono-N-dealkylated metabolite in serum, urine, and saliva. We used a mu-Bondapak CN column and an acetate buffer mobile phase containing methanol. Retention times for the two compounds and the internal standard, p-chlorodisopyramide, were 3.4, 4.1, and 6.3 min, respectively. The lower limits of sensitivity for drug and metabolite were 50 and 80 micrograms/L, respectively, with maximum coefficients of variation of 4.6 and 12%, respectively. Currently used antiarrhythmic drugs did not interfere with the analysis of disopyramide, and the pharmacokinetics of the drug, obtained from studies of one subject, agree well with reported values.
Incorrect least-squares regression coefficients in method-comparison analysis.
Authors: Cornbleet P J , Gochman N 
Published: January 2020

Abstract
The least-squares method is frequently used to calculate the slope and intercept of the best line through a set of data points. However, least-squares regression slopes and intercepts may be incorrect if the underlying assumptions of the least-squares model are not met. Two factors in particular that may result in incorrect least-squares regression coefficients are: (a) imprecision in the measurement of the independent (x-axis) variable and (b) inclusion of outliers in the data analysis. We compared the methods of Deming, Mandel, and Bartlett in estimating the known slope of a regression line when the independent variable is measured with imprecision, and found the method of Deming to be the most useful. Significant error in the least-squares slope estimation occurs when the ratio of the standard deviation of measurement of a single x value to the standard deviation of the x-data set exceeds 0.2. Errors in the least-squares coefficients attributable to outliers can be avoided by eliminating data points whose vertical distance from the regression line exceed four times the standard error the estimate.
Automated measurement of total cholesterol and triglycerides, in "tandem," on the discrete sample analyzer, Gilford System 3500.
Authors: Smith L , Lucas D , Lehnus G 
Published: January 2020

Abstract
We have developed an automated procedure on a discrete sample analyzer, Gilford System 3500, which alternately measures both total serum cholesterol and triglyceride concentrations as a "tandem" procedure. We used Dow Diagnostic's fully enzymatic, colorimetric reagents and aqueous standards to calculate unknowns ratiometrically. Cholesterol and then triglyceride reagent are dispensed into alternate cups; the produced color at 500 nm is measured after an ambient temperature incubation of 20 min. Reagent and sample carryover is less than 1.6%. Correlation coefficients of 0.997 for comparison for both automated tests with the manual methods at 30 degrees C and a typical CV of less than 2.0% show this "tandem" procedure to be reliable and accurate.
The elution profile of vitamin D2 metabolites from sephadex LH20 columns.
Authors: Hay A W , Jones G 
Published: January 2020

Abstract
A metabolite of vitamin D2 in the tissues of primates fed this vitamin co-migrates to a significant extent with 24,25-dihydroxyvitamin-D3 on columns of Sephadex LH20, with chloroform/n-hexane (60/40 by vol) as eluent. In individuals receiving vitamin D2 and in individuals with scant exposure to sunlight this metabolite, which we believe to be 25,26-dihydroxyvitamin-D2, may yield falsely higher concentrations of apparent 24,25-dihydroxyvitamin-D3 if separation on LH20 is used.
Spectral analysis of urinary reactions: a preliminary study based on a novel concept.
Authors: Wilding P , Bullock D G , Kricka L J , Morriss P , Holder R L 
Published: January 2020

Abstract
The concept of spectral analysis of urinary reactions (a range of simple chemical tests combined with pattern analysis) is described. A preliminary study in which we used 10 nonspecific tested on untimed urine specimens from 20 controls and 20 diabetics, matched for age and sex, suggested that a combination of these tests could be used to separate diabetics from healthy subjects. This combination, however, did not prove satisfactory for a further group of 13 diabetics. Closer examination revealed that factors such as therapy and glycosuria affected the results of these tests. This approach, which should extend the usefulness of urinalysis, may prove viable when larger groups, and possibly a different set of tests, are used to establish a more robust combination of tests.
Maltotetraose as a substrate for enzyme-coupled assay of amylase activity in serum and urine.
Authors: Whitlow K J , Gochman N , Forrester R L , Wataji L J 
Published: January 2020

Abstract
The use of maltotetraose ss a new substrate for the enzyme-coupled determination of amylase activity in biological fluids was developed by Beckman Microbics. We evaluated a manual and a centrifugal analyzer version of the method in comparison with two commonly used manual starch-dye amylase techniques: Roche Amylochrome and Pharmacia Phadebas. Both maltotetraose amylase procedures proved to be rapid and precise, and results correlated satisfactorily with the starch-dye methods for serum and urine samples.
Immunochemical determination of human immunoglobulins: use of kinetic turbidimetry and a 36-place centrifugal analyzer.
Authors: Finley P R , Williams R J , Lichti D A , Griffith F , Thies A C 
Published: January 2020

Abstract
We describe the measurement of human immunoglobulins IgG, IgA, and IgM in diluted sera, with diluted commercial monospecific antisera, with use of a 36-place centrifugal analyzer (RotoChem IIa; American Instrument Co., Silver Spring, MD 20920). The assay involves a two-point kinetic turbidimetric technique. The changes in absorbance at 340 nm between 10 and 255 s are taken for standard curve construction with use of a computer-generated cubic least-squares fit. Patients' samples are quickly calculated from the stored curve. Multiple time-interval readings are taken to observe the reaction kinetics. The lowest detectable concentrations are: IgG, 5 mg/L; IgA, 20 mg/L; and IgM, 20 mg/L. Correlation with radial immunodiffusion was excellent. Precision, accuracy, linearity, and sensitivity were very acceptable. Antigen or antibody excess can be easily detected. The accuracy of the proposed method when measuring idiotypic monoclonal proteins is greater than radial immunodiffusion. Up to 30 patients' samples can be analyzed at one time, and calculation of test results by use of the computer program is efficient and rapid.
Radioimmunoassay of 17 alpha-hydroxyprogesterone in saliva, parotid fluid, and plasma of congenital adrenal hyperplasia patients.
Authors: Walker R F , Read G F , Hughes I A , Riad-Fahmy D 
Published: January 2020

Abstract
We report a radioimmunoassay sensitive enough to determine 17 alpha-hydroxyprogesterone concentrations in 200 microliter of parotid fluid or mixed whole saliva. Because the correlation of concentrations in matched samples of parotid fluid and saliva was excellent (r = 0.98), we exclusively used saliva, which is easier to collect, in later studies. The assay is specific; saliva samples assayed with and without thin-layer chromatographic purification showed no significant difference. The assay is also precise, and has a lower limit of sensitivity of 4 pg per assay tube. In 14 patients having congenital adrenal hyperplasia from a C21-hydroxylase enzyme deficiency, all of whom were receiving cortisol replacement therapy, the range in 17 alpha-hydroxyprogesterone concentrations observed in saliva (67-26,300 pmol/L) was about 20-fold that seen in 32 healthy children (90-1520 pmol/L). The close correlation (r = 0.91) between 17 alpha-hydroxyprogesterone concentrations in matched samples of saliva and plasma from these patients indicates that determination of steroids in saliva could well replace determination in plasma. This concept is supported by 17 alpha-hydroxyprogesterone concentrations monitored throughout 24 h from one patient and following stimulation with synthetic corticotropin in another patient.
Measurement of aspartate aminotransferase activity: effects of oxamate.
Authors: Rej R 
Published: January 2020

Abstract
Oxamate, a potent inhibitor of lactate dehydrogenase, is shown also to inhibit aspartate aminotransferase activity, both in human serum and in purified isoenzymes of human origin. The inhibition was competitive with respect to 2-oxoglutarate for both isoenzymes. The apparent Ki was 29 mmol/L for the cytoplasmic enzyme and 17 mmol/L for the mitochondrial enzyme. Noncompetitive inhibition was found between oxamate and aspartate. At saturating concentrations of substrate (2-oxoglutarate greater than or equal to 15 mmol/L, L-aspartate greater than or equal 150 mmol/L) oxamate inhibited the mitochondrial enzyme but had less effect on the cytoplasmic isoenzyme. Oxamate at 40 mmol/L inhibited the enzyme in serum by 11 and 9% in assays containing 2-oxoglutarate at 6.7 and 15 mmol/L, respectively. This concentration of oxamate inhibited enzyme activity in serum by 5% more than did the same concentration of Cl- (itself an inhibitor). Oxamate (less than or equal to 30 mmol/L) had no measurable effect on the stability or activity of porcine malate dehydrogenase. Until the effects of its inhibitory properties are considered, addition of oxamate to suppress lactate dehydrogenase-mediated side reactions in the assay of aspartate aminotransferase cannot be recommended.
A Liquid-Chromatographic Analysis for Indomethacin in Serum
Authors: Soldin Steven J , Gero Terese 
Published: January 2020

Abstract
We describe a "high-performance" liquid-chromato-graphic assay for measuring indomethacin in 100 µL of serum. The procedure involves an ethylene dichloride extraction of indomethacin and internal standard (2,5-diphenyloxazole) from serum. The organic phase is separated and evaporated, and the residue dissolved in a 40/60 (by vol) mixture of potassium phosphate buffer (10 mmol/L, pH 3.0) and acetonitrile. An aliquot of this solution is injected into the chromatograph. We used a µ-Bondapak C-18 column with the above-mentioned buffer system as mobile phase, a flow rate of 3.0 mL/min, and a column temperature of 40 °C. Indomethacin and the internal standard are detected by their absorbance at 200 nm and quantitated by measuring peak heights. The procedure allows for the reliable analysis for indomethacin in serum at concentrations &gt; 100 µg/L. Analytical recovery for indomethacin was 66-68%, and the method affords good day-to-day precision (CV &lt;11 %).
Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer.
Authors: Li P K , Shull B C 
Published: January 2020

Abstract
We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.
Predictive values of thyroxine, thyrotropin, and triiodothyronine concentrations in serum.
Authors: Homburger H A , Hewan-Lowe K 
Published: January 2020

Abstract
The predictive values of total thyroxine, thyrotropin, and total triiodothyronine concentrations in serum for clinically apparent and subclinical hypothyroidism and hyperthyroidism were determined by retrospective analysis of clinical cases chosen from the frequency distributions of hormone test results. Very low total thyroxine concentrations, less than 25 microgram/L, were specific for hypothyroidism. Most subclinical hypothyroid cases had intermediate or low total thyroxine concentrations, 35-60 microgram/L, with moderately increased thyrotropin concentrations, greater than 12 milli-int. units/L. Thyrotropin cut-off concentrations were identified that had predictive values greater than 90% for classifying untreated and hormone-treated hypothyroid cases. Above-normal total thyroxine concentrations, regardless of absolute value, were not specific for hyperthyroidism, because binding-protein alterations related to estrogen taking were prevalent and produced occasional marked increases in serum total thyroxine. Nevertheless, cut-off concentrations for serum total thyroxine and total triiodothyronine were identified that had a predictive value greater than 90% for hyperthyroidism, without necessitating measurement of the capacities or concentrations of hormone-binding proteins.
Microchemical analysis for 13 constituents of plasma from healthy children.
Authors: Cheng M H , Lipsey A I , Blanco V , Wong H T , Spiro S H 
Published: January 2020

Abstract
Normal values for 13 chemical constituents of plasma were estimated from results for 837 presumably healthy children. Ninety microliters of specimen was analyzed for lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, inorganic phosphorus, total calcium, total cholesterol, total proteins, albumin, uric acid, urea nitrogen, alanine aminotransferase, total bilirubin, and glucose. We used two Abbott ABA-100 Bichromatic Analyzers interfaced directly to the ABA Data Management System. For each test age- and sex-related variations were assessed and normal values were estimated for six different age groups.
Enzyme immunoassay of estrogen-like substances in plasma, with polyethylene glycol as precipitant.
Authors: Osterman T M , Juntunen K O , Gothoni G D 
Published: January 2020

Abstract
We devised an enzyme immunoassay for plasma estrogen-like substances in pregnancy, using estriol covalently linked to horseradish peroxidase. Free and bound steroid were separated by use of polyethylene glycol reagent. The assay satisfies the normal criteria of specificity and precision. Results obtained by radioimmunoassay and enzyme immunoassay agreed well. Our assay is particularly applicable in smaller clinical laboratories to routine determination of plasma estriol in pregnancy.
Serum ferritin compared with other indices of iron status in children and teenagers undergoing maintenance hemodialysis.
Authors: Ellis D 
Published: January 2020

Abstract
To determine how best to assess iron status, I studied 12 young renal patients (ages 5.5 to 20 years) undergoing regular hemodialysis treatments. Iron balance was estimated by monitoring iron loss ascribable to blood loss during dialysis and diagnostic testing, and iron intake in the form of oral and intravenous iron supplements and blood transfusions. Traditional methods of evaluating iron status--measurement of hemoglobin, erythrocyte indices, reticulocyte count, iron, and transferrin--were compared with measurement of serum ferritin. The serum ferritin measurements provided superior information. In three cases this method was superior to visual assessment of bone marrow stained for iron.
Double-antibody method and the protein-A-bearing Staphylococcus aureus cells method compared for separating bound and free antigen in radioimmunoassay.
Authors: Gupta R K , Morton D L 
Published: January 2020

Abstract
We compared the protein-A-bearing Staphylococcus aureus immunoadsorbent to the double-antibody precipitation method for separating bound and free radiolabeled antigen in a radioimmunoassay. With human albumin (antigen) and rabbit anti-human albumin (antibody) as a model, our results indicate that formalin-fixed, heat-killed S. aureus cells could be substituted for the double-antibody precipitation method. Ease of preparation and high adsorption capacity of protein-A-bearing S. aureus for most mammalian IgG make this method economical and time saving.
Simultaneous measurements of acetaminophen and salicylate in plasma by liquid chromatography.
Authors: Miceli J N , Aravind M K , Cohen S N , Done A K 
Published: January 2020

Abstract
We describe a "highly-performance" liquid chromatographic method in which 8-chlorotheophylline is used as an internal standard to determine acetaminophen and salicylate simultaneously in plasma samples. Therapeutic as well as toxic concentrations can be determined on samples as small as 50 micro L, which makes the method particularly useful for determinations on samples from young children. The procedure requires a simple extraction of the drugs, and the chromatography is completed in 6 min.
Calibration and monitoring of spectrometers and spectrophotometers.
Authors: Frings C S , Broussard L A 
Published: January 2020

Abstract
We have delineated some of the factors affecting the performance of spectrometers and spectrophotometers in the clinical laboratory and have presented some of the methods for verifying that these instruments are functioning properly. At a minimum, every laboratory should perform periodic inspections of spectrometric functions to check wavelength calibration, linearity of detector response, and stray radiation. Only through such an inspection program can a laboratory ensure that these instruments are not contributing to inaccurate analytical results.
The use of linear models and matrix least squares in clinical chemistry.
Authors: Deming S N , Morgan S L 
Published: January 2020

Abstract
We present a unified approach to the use of linear models and matrix least squares with the intention of providing a better understanding of the techniques themselves and of the statistics that arise from these techniques as they are used in clinical chemistry. Emphasis is placed on the importance of appropriate experimental designs and adequately precise measurement processes for efficiently obtaining the desired information.
Microencapsulated antibodies in radioimmunoassay--I. Determination of digoxin.
Authors: Halpern E P , Bordens R W 
Published: January 2020

Abstract
We describe the application of the microencapsulated-antibody technique to the radioimmunoassay of digoxin in serum. Droplets of emulsified rabbit antibody are microencapsulated in a semipermeable nylon membrane by an interfacial polymerization technique. The antibody microcapsules are incubated with 125I-labeled digoxin and unlabeled digoxin for 15 min at 37 degrees C, then free and bound digoxin are separated by centrifugation. Subtherapeutic, therapeutic, and toxic concentrations of digoxin in sera can be determined, with use of a standard curve prepared by use of known amounts of digoxin. With this technique we obtained an intra-laboratory correlation coefficient of 0.945 for 100 patients' sera and one of 0.940 for interlaboratory results for 21 sera (10 laboratories) when compared to a routine clinical laboratory radioimmunoassay for digoxin. Icterus, lipemia, hemoglobin, or disproteinemia had no effect on the analytical recovery of digoxin. The standard curve was linear to 6 microgram/L; the sensitivity was 0.25 microgram/L.
Preparation and stability of a liquid creatine kinase isoenzyme control from rabbit serum.
Authors: Lum G 
Published: January 2020

Abstract
The MB isoenzyme of creatine kinase (CK) may be prepared in vitro from rabbit serum containing only the MM and BB isoenzymes, by means of a hybridization technique. The MM and BB dimers dissociate in 4 mol/L urea, which allows random recombination of M and B monomers. A liquid CK-isoenzyme control can be made from mixtures of rabbit sera obtained after hybridization and stabilized with glycerol and 25 mmol of 2-mercaptoethanol per liter. A liquid control stored at 4 degrees C showed good stability over a three-month period, declining to a mean residual activity of CK of approximately 90% after three weeks and a mean residual activity of MM, MB, and BB of 80--85% after six weeks. At 25 degrees C, CK activity of the liquid control declined to 75--80% after the fourth week. CK-BB at 25 degrees C was the least stable isoenzyme, declining to 75% after the third week and reaching 60% of activity after 12 weeks. CK-MB and CK-MM showed approximately 10--15% less stability at 25 degrees C than at 4 degrees C.
Factors affecting the concentration of triacylglycerols (triglycerides in plasma: reference values for adults.
Authors: Steinmetz J , Panek E , Siest G , Gueguen R 
Published: January 2020

Abstract
We studied factors influencing concentrations of triglycerides in the blood of a presumably healthy population of about 9000 persons. Using multi-dimensional analysis, we show, in addition to various related to sex and age, the relation between triglycerides and uric acid, overweight, arterial blood pressure, use of oral contraceptives (in women), consumption of alcohol and tobacco, and lack of physical exercise. These factors were classified as a function of their discriminative power by the statistical method of segmentation. We thus chose the following factors as criteria for exclusion from a reference population for the values of triglycerides in blood: in men 20 to 39 years old, overweight more than 90%; in men 40 to 59 years old, overweight of more than 115%, consumption of more than half a liter of wine per day or of more than 11 cigarettes, use of medicines, and a blood uric acid exceeding 420 mumol/L; in women 20 to 39 years old, contraceptives and overweight; in women 40 to 59 years old, overweight or more than 130% and the intake of medicines. At the 97.5th percentile of the reference population as compared with a non-selected population, the values were 80% less for men 20 to 39 years old, 95% less for men 40 to 59 years old, and only 26 to 30% less for women 20 to 59 years old.