bluuebunny/crossref_metadata_2025 huggingface dataset:
Concurrent determination of total serum calcium and magnesium by thermometric titration with ethylenediaminetetraacetate.
Authors: Callicott R H , Carr P W
Published: January 2020

Total serum calcium and magnesium may be determined in one thermometric titration, with disodium ethylenediaminetetraacetate as the titrant. A 1-ml serum sample is diluted with 1 ml of tris(hydroxymethyl)aminomethane buffer (pH 8) and titrated at a constant rate with a motorized syringe buret. Results by the thermometric method compared well with those by atomic absorption spectroscopy.
Effect of reaction initiator on human lactate dehydrogenase assay.
Authors: Buhl S N , Jackson K Y , Lubinski R , Vanderlinde R E
Published: January 2020

Human lactate dehydrogenase isoenzymes I and V have decreased activities when the reaction is initiated with lactate. No loss in lactate dehydrogenase I activity was found when the reaction was initiated with enzyme or NAD+. For lactate dehydrogenase V an NAD+-initiated reaction, as compared to an enzyme-initiated reaction, yields lower activity in sodium pyrophosphate buffer but higher activity in tris(hydroxymethyl)aminomethane buffer. Both isoenzymes have higher lactate-to-pyruvate activity when assayed in the latter buffer than when assayed in the former. Human lactate dehydrogenase V (but not I) exhibited different activities when assayed with lactate from two different commercial sources. Human lactate dehydrogenase assayed by the pyruvate-to-lactate reaction is not affected by the choice of reaction initiator.
Reduction of sample size on the Technicon SMA 6/60 continuous-flow analyzer.
Authors: Shihabi Z K , Turner J C
Published: January 2020

The manifold of the Sequential Multiple Analyzer SMA 6/60 (4 + 2) has been modified to decrease serum sample size to 90 mul, by using a common diluent for all six channels and recycling the discard of each dialyzer into the next one. The modification can be made in less than 4 h without the need for any additional parts; the modified manifold requires one-third fewer pump lines and fewer reagents, thus reducing operating costs and simplifying instrument maintenance, while retaining the same precision, speed, low carryover, and linearity of the production model.
Evaluation of benefits of screening tests done immediately on admission to hospital.
Authors: Durbridge T C , Edwards F , Edwards R G , Atkinson M
Published: January 2020

Evidence was sought of improved inpatient progress and reduced hospital costs when a battery of investigations were done at the time a patient was admitted to hospital. The outcome in 500 admission-tested patients was compared with that in two other groups of 500 control patients. No significant differences were found among the three groups in a variety of indices of inpatient progress. Because of an estimated 64% increase in the cost of investigating inpatients with admission testing, the total cost of hospital care was increased by about 5%. Under the conditions of this study, admission testing added to the cost of hospitalization, without associated evidence of benefit to the patient.
Rates of disappearance from plasma of enzymes labeled by coupling with a radioactive lodo-ester.
Authors: Qureshi A R , Wilkinson J H
Published: January 2020

Lactate dehydrogenase-5 and creatine kinase from rabbit muscle were labeled by coupling with N-hydroxysuccinimidyl 3-(4'-hydroxy-[3',5'-125I]diiodophenyl)propionate. After purification, the analytical recovery of catalytically-active labeled enzyme averaged 90% for lactate dehydrogenase, 81% for creatine kinase. The labeled enzymes were injected intravenously into rabbits and disappearance from plasma of catalytic activity and radioactivity was measured. The disappearance curves for lactate dehydrogenase-5 differed considerably from those observed with the enzyme labeled by direct iodination. The discrepancy was due to rapid hydrolysis in vivo of the labeled amide-enzyme linkage, because about 50% of the injected radioactivity appeared in the urine as 125I-labeled 3-(4'-hydroxy-3',5'-diiodophenyl)propionic acid within 4-8 h of injection. Similar outputs were observed after administration of this acid to rabbits. The free acid was also detected in the urines of rabbits within 4-8 h of the intravenous injection of creatine kinase labeled similarly. We conclude that this method of labeling is unsuitable for preparing radioactive enzymes for study of their catabolism.
Addition of triglyceride to serum for use in quality control and reference.
Authors: Bonderman D P , Proksch G J , Bonderman P W
Published: January 2020

We describe a simple method in which a water-soluble mixture of triocatanoin and a surfactant, "Triton X-114," are used in preparing solutions of triglycerides (triacylglycerols) in either human serum, solutions of albumin, or water. Analytical recovery added triglyceride was quantitative by two methods. The addition did not affect results of analyses for 18 other commonly measured constitutents of serum. When the triglyceride was added to either lipid-depleted human serum or bovine serum albumin solution and lyophilized, subsequent solutions were clear. The triglyceride/protein preparation was stable in lyophilized form for a year and in reconstituted serum for five days at 5 degrees C. Aquenous solutions appear to be stable indefinitely at room temperature.
Structure of some aliphatic dicarboxylic acids found in the urine of an infant with congenital lactic acidosis.
Authors: Lindstedt S , Norberg K , Steen G , Wahl E
Published: January 2020

Gas chromatography/mass spectrometry was used to identify a series of acids in urine and serum from a child who died 26 h after birth in severe metabolic acidosis with high lactate excretion. cis-5-Decene-1, 10-dioic acid and cis-5-dodencene-1, 12-dioic acid were synthesized and used as references. The following acids were found: hexane-1,6-dioic acid, octane-1,8-dioic acid, decane-1,10-dioic acid, dodecane-1,12-dioic acid, cis-5-decene-1,10-dioic acid, cis-5-dodecen-1,12-dioic acid, cis-5-tetradecene-1,14-dioic acid, trans-3-decene-1,10-dioic acid, and trans-3-dodecene-1,12-dioic acid. The concentration of C6 to C14 acids in the patient's urine was 3.7 mol/mol of creatinine; it was less than 0.2 mol/mol of creatinine in eight normal newborns and approximately 0.1 mol/mol of creatinine in a case of fructose-1,6-biphosphatase deficiency with lactic acidosis. 5-cis-Dodecenedioic acid was present in highest concentration: 1 mol/mol of creatinine in urine and 61 mumol/liter in serum. We propose that impaired beta-oxidation, probably at the acyl-CoA-dehydrogenase step, resulted in the formation of the observed acids. The parents were consanguineous, and a sibling died with the same clinical picture, which suggests a genetic defect.
Improved method for determining serum protein concentrations in the far ultraviolet.
Authors: Ressler N , Gashkoff M , Fischinger A
Published: January 2020

We examined the feasibility of measuring absorbance in the far ultraviolet for serum protein determination with a medium-priced, double-beam spectrophotometer. The method has been simplified by using an automatic dilutor to dilute the serum, and a flow-through cell and recorder in conjunction with the spectrophotometer. Because it is only necessary to dilute the serum and determine its absorbance, the procedure is quite rapid. As compared to the biuret reaction, interferences from hemolysis have been about halved. Interferences owing to light scattering by turbid sera have also been appreciably decreased by use of an anionic detegent (sodium dodecyl sulfate) as a serum diluent. Comparisons of the present method to the biuret and Kjeldahl methods indicate that it is relatively accurate, and is practical for routine use.
Correlation between estrogen receptor protein and carcinoembryonic antigen in normal and carcinomatous human breast tissue.
Authors: Menendez-Botet C J , Nisselbaum J S , Fleisher M , Rosen P P , Fracchia A , Robbins G , Urban J A , Schwartz M K
Published: January 2020

We determined estrogen receptor protein and carcinoembryonic antigen in cytosols prepared from 189 human breast carcinoma tissues, 85 benign or normal breast biopsies, and 101 tissue specimens metastatic from breast carcinoma. Carcinoembryonic antigen was observed in 70% of the primary carcinomatous tissues, 15% of the benign or normal specimens, and 51% of the metastases. Ninety-six of the 189 primary carcinomatous specimens with increased concentrations of carcinoembryonic antigen were also positive for estrogen receptor protein, whereas 67 of the 72 benign or normal biopsies with low concentrations of carcinoembryonic antigen were also negative for estrogen receptor protein. All five fenign specimens with positive estrogen receptor protein and normal carcinoembryonic antigen concentrations were from fibroadenomas. The concordance between estrogen receptor protein and carcinoembryonic antigen in the primary carcinomatous tissue was 66%, in metastatic carcinoma 51%, and in benign and normal tissue 85%.
End-point parameter adjustment on a small desk-top programmable calculator for logit-log analysis of radioimmunoassay data.
Authors: Hatch K F , Coles E , Busey H , Goldman S C
Published: January 2020

We describe an improved method of logit-log curve fitting, by adjusting end-point parameters in radioimmunoassay studies, for use with a small desk-top programmable calculator. Straight logit-log analyses are often deficient because of their high sensitivity to small errors in the end-point parametes B0 and NSB (the actual measured activity in the tubes). The literature suggests techniques for adjusting these end-point parameters, but they require too much computing time and programming space to be used with a desk-top programmable calculator. The extension to the logit-log model presented here is easily handled by the programmable calculator and provides a good estimate of the change required in B0 and NSB to obtain a better fit. The program requires 1.5 min to run on our desk-top programmable calculator, and has resulted in improved data analysis for all of the 11 types of radioimmunoassay studied.
Unsuitability of porcelain crucibles for dry ashing of biological tissues for calcium analysis.
Authors: Meyer M , Meyer R A
Published: January 2020

At temperatures required for complete release of calcium from beef liver by dry ashing, porcelain crucibles release significant amounts of calcium into the ash, which leads to erroneously high calcium values in the samples. Heated, empty porcelain crucibles do not show released calcium. Both fused silica and platinum crucibles fail to show any significant interaction with the sample. Samples dry-ashed in fused silica crucibles were compared to samples subjected to the hot trichloracetic acid-acetic acid extraction method, which gave results not significantly different if the tissue was first minced. However, calcium was incompletely extracted by the hot acid from whole segments of liver weighing about 0.2 g.
Simplified radioimmunoassay for triiodothyronine: evaluation of a new commercial kit.
Authors: Balachandran S , Moses D C , Sisson J C , Patel S R
Published: January 2020

A new triiodothyronine (T3) radioimmunoassay kit offers simplicity of method, short incubation time, specificity, and reproducibility. 125I-labeled T3 and unknown serum (or standard) are added to alkaline buffered (pH 12.4) Sephadex G-25 columns; the T3 is freed of proteins with an alkaline buffer wash, antiserum is added, and the columns are incubated at room temperature for 2 h. "Free" hormone (i.e., unbound to antiserum) remains on the column after a second wash. The radioactivity on the column is counted and related to the total activity added. The T3 standards produced a straight line on log-logit plot; reactivity of analytical-grade thyroxine was 0.6% on weight basis; and the analytical recovery of T3 added to a T3-free serum was complete. Euthroid, hyperthyroid, and hypothyroid ranges were 0.74-2.64, 2.91-7.52, and 0-1.21 mug/liter, respectively. These values correlated well with both the clinical status of patients and with values obtained by an established radioimmunoassay method. The procedure is simply done; results may be obtained in less than 4 h.
Creatine kinase isoenzymes in cerebrospinal fluid in a case of brain damage.
Authors: Bayer P M , Gabl F , Granditsch G , Widhalm K , Zyman H , Deutsch E
Published: January 2020

We present a case of a 11/2-year-old boy with toxic enteritis, consecutive consumption coagulopathy, and sever brain damage. During the acute phase we found high activity of the BB isoenzyme of creatine kinase in cerebrospinal fluid, but not in the serum. Isoenzyme MM could also be found in the spinal fluid (37.9% of the total activity). We conclude that analysis for creatine kinase isoenzymes in spinal fluid is of clinical importance.
The free-falling drop detector--a nover fluorescence detector for high-performance liquid chromatography.
Authors: Martin F , Maine J , Sweeley C C , Holland J F
Published: January 2020

A novel fluorescence detector for high-performance liquid chromatography has been designed to minimize the instrumental limitations of conventional flow-through, fluorometers. This unit contributes less than 5 mul to the "dead volume" of the chromatographic system. Sensitivity comparable to that of existing flow-through fluorometers has been attained without optimizing instrumental parameters. Performance of the unit has been evaluated with reference samples containing saccharides typical of glycosphingolipids. Future improvements are discussed.
Instrumental sample-preparation technique for an automated immunohematology assay system.
Authors: Blume P , Polesky H F , Mathys J , Hanson M , Taylor D G
Published: January 2020

In the course of the development of an automated immunohematology assay system, we have produced, in prototype form, an instrumental device capable of accepting an unmeasured quantity of whole, anticoagulated blood and deriving from it multiple fixed-volume aliquots of plasma and cells.
Diagnosis of infectious hepatitis by multicomponent analysis with use of field ionization mass spectrometry.
Authors: Anbar M , Dyer R L , Scolnick M E
Published: January 2020

Field ionization mass spectrometry has been applied to multicomponent analysis of metabolites in human urine for the diagnosis of metabolic disorders, exemplified here by infectious hepatitis. The molecular weight profiles of carboxylic acids and of "neutral" metabolites in the urine of patients with infectious hepatitis were compared with those in urine of normals. The "neutral" metabolites showed 24 characteristic spectral differences in the range 68 to 215 atomic mass units, which provided correct diagnoses in 100% of the cases and a "diagnostic power" of unity. These results are even more encouraging than those obtained earlier with the acidic metabolites, where 11 mass numbers were found in the same mass range to be useful for correct diagnoses in 91% of the cases. The measurements were performed on urine samples preextracted on Amberlite XAD-2 columns. We used a quadrupole mass spectrometer interfaced with a multichannel analyzer for mass analyses.
Profiles of ultraviolet-absorbing components of urine from autistic children, as obtained by high-resolution ion-exchange chromatography.
Authors: Lis A W , Mclaughlin I , MPCLAUGHLIN R K , Lis E W , Stubbs E G
Published: January 2020

Urines from 19 autistic children (3 female, 16 male) were analyzed by high-resolution, high-pressure anion-exchange chromatography. The results showed abnormalities in the excretion of hippuric acid, 4-hydroxyhippuric acid, and N1-methyl-2-pyridone-5-carboxamide, the end product of the nicotinic acid pathway. Considerations as the metabolic origin on the 4-hydroxyhippuric acid are discussed and related to the possibility of bacterial action and malabsorption.
Automated computer analysis for enzyme-multiplied immunological techniques.
Authors: Rodbard D , McClean S W
Published: January 2020

The dose/response curve in enzyme-multiplied immunoassays (EMIT) and related techniques may be described by the same "four-parameter logistic function" as has proven useful in radioimmunoassays, immunoradiometric assays (IRMA), and two-site immunoradiometric ("sandwhich") assays. This function provides an empirical description of the dose/response curve by use of an objective least-squares regression analysis, with the advantages of computerization and automation. This facilitates further statistical analyses, quality control, estimation of precision for an unknown, and improved, objective estimation of the sensitivity or minimal detectable dose.
Enzyme immunoassay of serum thyroxine with the "Autochemist" multichannel analyzer.
Authors: Galen R S , Forman D
Published: January 2020

We have modified the homogeneous enzyme immunoassay of thyroxine and have adapted it to the AutoChemist. Both enzyme immunoassay and radioimmunnoassay procedures were performed on 2016 patients' sera on which thyroxine determinations had been ordered. We find the automated enzyme immunoassay to be precise and accurate, and for the first time it permits total automation of an immunoassay on a multichannel biochemical-profiling instrument. More importantly, it represents the first time that a thyroid-function test has been included in a multitest biochemical screening profile performed on a single automated instrument.
Simplified micro-scale procedure for preparing samples for theophylline determination by liquid chromatography.
Authors: Nelson J W , Cordry A L , Aron C G , Bartell R A
Published: January 2020

We describe an improved procedure for the preparation of plasma or serum for determination of theophylline by reverse phase high-performance liquid chromatography. Quantitative results are available in less than 30 min from receipt of sample. The chromatogram is complete in 8 to 16 min, which includes the use of an internal standard. Sample preparation consists of simple solvent denaturation of the sample proteins, and centrifugation to remove protein before chromatography. No precolumn is required to pretect the separating column. No interference was noted when sodium or lithium heparin or ethylenediaminetetraacetate were used as anticoagulants, but citrate treatment proved to be unsatisfactory because of a highly absorbing band that eluted with the same retention volume as theophylline.
Characteristics of binding between reagent-strip indicators and urinary proteins.
Authors: Bowie L , Smith S , Gochman N
Published: January 2020

We describe the binding characteristics of two indicator dyes that are widely used in commercial "dip-stick" indicators for protein in urine. Binding was studied by both gel filtration chromatography and by spectrophotometric titrations. The results demonstrate that the well-known lack of sensitivity of these strips to proteins other than albumin relates to the number and affinity of binding sites on these proteins as compared to albumin. The data suggest that these test strips can screen more effectively for albuminuria than for other proteinurias.
Comparison of human prostatic acid phosphatase by measurement of enzymatic activity and by radioimmunoassay.
Authors: Foti A G , Herschman H , Cooper J F
Published: January 2020

We compared results of measurement of prostatic acid phosphatase activity in serum and various tissues by enzymatic assay and radioimmunoassay. By enzymatic assay, activity in serum is lost rapidly, even at room temperature. In contrast, there was no change in antigenic activity during 48 h by radioimmunoassay. The radioimmunoassay was more specific in 12 tissues and in serum than were several enzymatic assays that make use of inhibitors of the enzyme. The enzymatic assay resulted in 26.6% (24/90) false positives from non-prostatic cancer patients. In contrast, with radioimmunoassay there were only 5.5% (5/90) false positives. We conclude that immunological detection of prostatic acid phosphatase is the more reliable technique.
Measurement of plasma lipoproteins by electrophoresis on polyacrylamide gel.
Authors: Muñiz N
Published: January 2020

Results of densitometric analysis of lipoprotein peaks after electrophoresis on polyacrylamide gel and values obtained by the classical method of ultracentrifugation/precipitation correlate well. The correlation coefficients for high-density, low-density, and very-low-density lipoproteins are 0.85, 0.99, and 0.99, respectively. Thus the densitometric method for lipoprotein analysis appears to be suitable for routine clinical application.
Zinc, iron, copper, and magnesium concentrations in tissues of rats fed various amounts of zinc.
Authors: Kang H K , Harvey P W , Valentine J L , Swendseid M E
Published: January 2020

An experiment was conducted with rats to determine the effects on the tissue concentrations of Zn, Fe, Cu, and Mg of feeding various amounts of zinc. The rats were pair-fed one of the following diets for four weeks: Diet A, a zinc-deficient diet; a diet containing the recommended amoun of zinc (diet A plus 55 microgram of zinc per gram of diet), or diet A plus 550 microgram zinc per gram of diet. Concentrations of these elements in various tissues were determined by atomic absorption spectrometry after wet digestion. Feeding the rats zinc-supplemented diets resulted in increased zinc in blood, heart, kidney, and liver, and a marked decrease of iron in kidney and liver. Concentrations of the other two elements were unchanged in all tissues. Thus, the effect of zinc in decreasing iron concentrations in liver, observed by several investigators when rats were fed toxic amounts of zinc, also occurs when zinc is administered in normal or subtoxic amounts.
Application of a method for correcting an observed regression between change and initial value for the bias caused by random errors in the initial value.
Authors: Blomqvist N , Cederblad G , Korsan-Bengtsen K , Wallerstedt S
Published: January 2020

When studying the correlation between the change of a variable during treatment and the value before treatment, random errors (errors of measurement as well as intra-individual biological variation) may yield seriously biased results. In the present work a method to adjust for this bias is presented. The method was applied to data from blood coagulation factor and plasma protein analyses in chronic alcoholics before and after one week of abstinence. It was found that many of the significant correlations were lost when the data were adjusted.
Radioimmunoassay for digoxin with a fully automated continuous-flow system.
Authors: Greenwood H , Landon J , Forrest G C
Published: January 2020

We describe a fully automated continuous-flow radioimmunoassay for digoxin with use of a Technicon AutoAnalyzer system. It makes use of antibodies linked to magnetizable particles; a magnet separates the bound and free fractions. The precise dispensing of reagents by the AutoAnalyzer system permits a small incubation volume (about 160 microliter) and the reproducible timing enables non-equilibrium conditions to be used. Thus a single sample is assayed in 15 min, with a sample throughput of 30/h. The standard curve ranges from 0.5 to 8.0 microgram/liter and is most precise between 1 and 3 microgram/liter, the between-assay coefficient of variation being less than 3%. There is no significant carryover between samples of high and low concentration, and results by the method correlate closely (r = 0.969) with those by an established manual assay in which charcoal separation is used.
Radioimmunoassay for MM and BB isoenzymes of creatine kinase substantiated by clinical application.
Authors: Fang V S , Cho H W , Meltzer H Y
Published: January 2020

We have developed a radioimmunoassay technique that is highly specific for measuring the MM isoenzyme of creatine kinase. The specificity of the radioimmunoassay for the BB isoenzyme was poor. In patients with treated Duchenne-type muscular dystrophy or untreated hypothyroidism, the MM isoenzyme, but not the BB isoenzyme value, was consistently above above normal. In the radioimmunoassay for the BB isoenzyme the antisera might cross react with other materials and the inactivated isoenzyme, but not with MM or MB isoenzymes.
Simplified radioimmunoassay of urinary drugs of abuse adsorbed on ion-exchange papers.
Authors: Alexander G J , Machiz S
Published: January 2020

A convenient screening procedure for presence of drugs of abuse in urine consists of two steps: adsorption of the drugs from urine onto a paper loaded with cation-exchange resin and detection of the adsorbed drugs by direct radioimmunoassay. The first step can be performed in the field, the second in a central laboratory. Storage and transport to the laboratory are simplified because specimens adsorbed on dried paper are stable and can be sent in letter-mail. In the laboratory, a small disc of the ion-exchange paper is exposed to antigen and antibody, rinsed, and tested for radioactivity. Discs treated with positive urines are more radioactive than discs from negative urines.
Comparison of immunoglobulin determinations in pathological sera by radial immunodiffusion and laser nephelometry.
Authors: Virella G , Fundenberg H H
Published: January 2020

Immunoglobulins G, A, and M were measured by radial immunodiffusion and by laser nephelometry in sera from 33 patients and in a preparation of purified colostral IgA. In general the results agreed for the two methods, with some exceptions attributed to the physicochemical characteristics of the immunoglobulins assayed: low-molecular-weight (monomeric) IgM gives falsely high values and IgA proteins (consisting predominantly of polymeric molecules) give falsely low values when assayed by radial immunodiffusion. Results from laser nephelometry apparently are not affected by the molecular-size characteristics of the proteins assayed.
Determination of cyanide and nitroprusside in blood and plasma.
Authors: Rodkey F L , Collison H A
Published: January 2020

A procedure was refined for quantitative isolation of cyanide by gas transfer from acidified blood or plasma samples. The cyanide was trapped in dilute alkali and quantified as the pyridine/pyrazolone complex. The within-day coefficient of variation was 2%, which increased to about 2.5% for the day-to-day variation. Nitroprusside used as a hypotensive agent in clinical medicine provides a risk of cyanide toxicity when the rate of administration or the total amount of drug given is excessive. A procedure was developed for measuring nitroprusside in the plasma of man and animals. Nitroprusside in the sample is quantitatively converted to cyanide by incubation with cystein solution at slightly alkaline pH. Methemoglobin is added to combine with the cyanide formed and prevent its destruction. On acidification, the total amount of cyanide originally present as free cyanide or as nitroprusside is liberated as HCN, isolated by gas transfer into a sodium hydroxide trap, and quantified by spectrophotometry. Nitroprusside present in the sample is calculated from the increase in cyanide observed in the cysteine-treated sample compared to that obtained without cysteine treatment. The method has been used to estimate in vitro stability of nitroprusside in aqueous solution, blood, and plasma. Blood cyanide and plasma nitroprusside concentrations were measured when sodium nitroprusside was infused into a baboon. Over 90% of the nitroprusside in blood is present in the plasma, suggesting that the drug crosses the erythrocyte membrane slowly.
Fluorescent assay of total serum cholesterol, with use of gas-liquid chromatography to study saponification efficiency.
Authors: Majeski E J , Seltzer E J , Carter P L , Howlett D R , Stuart J D
Published: January 2020

We describe a fluorescent determination of total cholesterol in serum for which the accuracy and precision are comparable to that for the method of Abell-Kendall, a method of generally accepted accuracy. By the use of quality reagents and the rigorous exclusion of water, the strong fluorophor that develops on reacting concentrated sulfuric acid with cholesterol can be used to quantitatively determine the total cholesterol in serum. We used gas-liquid chromatography to monitor the extent of saponification of the cholesterol esters, because we found them to have fluorescent efficiencies that differed from that of free cholesterol. Sodium methoxide in methanol/methylene chloride (1/3 by vol) was shown by gas-liquid chromatography to very effectively saponify the cholesterol esters in serum.
Colorimetric determination of phospholipids by use of molybdophosphate, and its application to amniotic fluid.
Authors: Worth H G , Wright D J
Published: January 2020

We studied the reaction between molybdophosphoric acid and lecithin. The resulting complex was isolated and shown to contain molybdophosphate and lecithin in the molar ratio 1/3. It is insoluble in water but soluble in chloroform, and the reaction is specific for molecules containing electrophilic nitrogen, indicating good specificity in biological fluids for nitrogen-containing phospholipids. In solution the complex may be reduced, yielding molybdenum blue. We applied the reaction to the measurement of phospholipid concentrations in amniotic fluid. As compared with procedures involving either digestion or the determination of lecithin/sphingomyelin ratio, the present technique is faster and its analytical precision exceeds that of the lecithin/sphingomyelin ratio determination. Although results by the three methods do not correlate well, the predictive value of the present method appears to be comparable with the other two.
Radioimmunoassay for flupenthixol in plasma.
Authors: Robinson J D , Risby D
Published: January 2020

We describe a radioimmunoassay for the neuroleptic drug flupenthixol, suitable for routine monitoring of its concentration in blood. Antibodies for the assay were raised in a sheep against a 7-carboxyflupenthixol/ovalbumin conjugate. The resulting assay, with [3H] flupenthixol as the label, is capable of detecting 2.0 microgram of flupenthixol per liter, in a 100-microliter plasma sample. The antiserum shows no cross reactivity with tricyclic drugs and low interference from the major metabolites of flupenthixol. Concentrations in plasma after a single oral dose of flupenthixol have been followed in one volunteer. Peak values were reached after 3 h. Determinations of flupenthixol after fortnightly intramuscular depot injections of the sustained-release preparation, flupenthixol decanoate, showed the extent of fluctuations during this period.
Effects of ethanol (0.75 g/kg body weight) on the activities of selected enzymes in sera of healthy young adults: 2. Interindividual variations in response of gamma-glutamyltransferase to repeated ethanol challenges.
Authors: Freer D E , Statland B E
Published: January 2020

We measured individual temporal changes in gamma-glutamyltransferase activity in serum after four consecutive ethanol challenges in each of eight apparently healthy volunteers. Each challenge consisted of ingesting 0.75 g of ethanol per kilogram of body weight on two evenings, followed by five days of abstention during which the activity was assessed at regular intervals. A nine-day abstention period preceded the study, and initial baseline activity was determined. The highest values for the group mean activity were +12%, +11%, +22%, and +18% greater than baseline after the first, second, third, and fourth ethanol challenges, respectively. We noted marked intra-individual and interindividual variation in the enzymic response; peak values ranged from +1% in one subject to +57% in another. The possible causes for these biological variations are discussed.
Albumin/calcium association at different pH, as determined by potentiometry.
Authors: Fogh-Andersen N
Published: January 2020

Calcium binding by albumin was determined potentiometrically at physiological ionic strength and temperature as a function of pH. The binding data indicate at least 30 different binding sites with different association constants and different H+ interaction. One site appears to be responsible for the major binding at physiological pH and substance concentration of free calcium, together with three other sites that bind with less affinity.
Removal of interference by erythromycin, phenazopyridine, and methenamine mandelate in the Porter-Silber reaction.
Authors: Furuya E
Published: January 2020

Erythromycin, phenazopyridine, methenamine mandelate, acetazolamide, and ascorbic acid reportedly interfere with the Porter-Silber reaction in the determination of urinary 17-hydroxycorticosteroids. Sodium bisulfite, added to the urine after hydrolysis with glucuronidase, removed almost all nonsteroidal interferences in urine from healthy adults medicated with the first three drugs, but such studies proved that acetazolamide and ascorbic acid do not interfere with the Porter--Silber reaction, whether or not sodium bisulfite is added.
A solid-phase enzyme immunoassay for serum ferritin.
Authors: Thériault L , Pagé M
Published: January 2020

We describe an enzyme immunoassay for human serum ferritin in which antibody adsorbed on polystyrene tubes is used. Adsorbed gamma-globulins against human ferritin were first allowed to react with ferritin and a second antiferritin antibody, labeled with alkaline phosphatase, was added. The amount of bound enzyme/antibody conjugate was proportional to the ferritin titer in the assay. This method offers stable reagents that can be kept for many months at 4 degrees C. The average values for ferritin in normal men and women were, respectively, 58 and 43 microgram/liter. The lowest detectable concentration was 5 microgram/liter.
Plasma alkaline phosphatase assay: interconversion of results by two methods.
Authors: Eaton R H
Published: January 2020

Two methods for measuring plasma alkaline phosphatase activity are compared: one makes use of phenyl phosphate, carbonate-bicarbonate buffer, and continuous-flow methodology; the other of p-nitrophenyl phosphate, diethanolamine buffer, and reaction-rate analysis. Results by the methods correlate well (r = 0.98) over a wide range of values (up to 10-fold the upper limit of normal). A factor can therefore be applied to convert results by one method into those that would be obtained by the other. The possibility that the presence of different proportions of isoenzymes in the plasma will affect this factor is considered. We have used the new method, with a conversion factor, as the routine method of alkaline phosphatase measurement in a clinical chemistry laboratory, with no problems.
Evaluation of Ames' "Clini-Tek".
Authors: Peele J D , Gadsden R H , Crews R
Published: January 2020

Reproducibility of reading "N-Multistix" dipsticks by a semi-automated urinalysis instrument (Ames' "Clini-Tek") has been described for artifically prepared samples. Glucose, ketone, urobilinogen, and nitrite showed high reproducibility (greater than 90%) for reading multiple samples at predetermined analyte concentrations. Determination of proteinuria showed the lowest proportion of false positives (2-3%) and false negatives (0%). Determination of hemoglobinuria and bilirubinuria by dipsticks were the least reproducible. Urobilinogen showed no interference from bilirubin in concentrations up to 32 mg/liter. Precision was high for results for quality-control capsules provided by the manufacturer.
Direct spectrophotometric determination of alpha-amylase activity in salive, with p-nitrophenyl alpha-maltoside as substrate.
Authors: Gillard B K , Marksman H C , Feig S A
Published: January 2020

We describe a simple, direct kinetic method for determination of salivary alpha-amylase (1,4, alpha-D-glucan 4-glucanohydrolase, EC 3.2.1.1). The assay makes use of a well-defined substrate, p-nitrophenyl alpha-maltoside, which is hydrolyzed by alpha-amylase to a chromogenic product, p-nitrophenol. Activity is determined by directly monitoring the increase in absorbance of the reaction mixture. Amylase activity can be defined in international (IUB) units of micromoles of product/min per liter of saliva. For 22 healthy subjects, the mean +/- SD of amylase activity in mixed saliva was 2.77 +/- 1.12 U/liter. Activity and instrumental response were linearly related over the entire range tested (0.224 to 11.90 U/liter). The within-run precision (CV) over this range was better than 3% for all but the lowest activities. Values obtained with this assay correlate well with those obtained with a modified Nelson-Somogyi saccharogenic method (r = 0.979). The precision and simplicity of this assay suggest that it is the method choice for determining amylase activity in human saliva.
Influence of oleic acid on serum lipoprotein-X in vitro.
Authors: Muckle T J , Edwards J A , Auckland P
Published: January 2020

Lipoprotein-X is no longer detectable in serum by either the agar gel-electrophoresis/polyanion precipitation technique or immunoelectrophoresis with specific antiserum after in vitro addition of oleic acid. Evidence is presented which indicates that this ostensible loss is due not to its destruction, but rather to altered electrophoretic mobility. The findings suggest an explanation for the well known post-heparin "disappearance" of lipoprotein-X, and indicate that caution may be needed in the interpretation of such lipoprotein-X testing of sera from subjects with increased concentrations of lysolipids in their blood.
Urinalysis by use of multi-test reagent strips: two dipsticks compared.
Authors: Smith B C , Peake M J , Fraser C G
Published: January 2020

We compared Ames' "N-Multistix" with Boehringer's "Combur-8" ("Chemstrip-8") multi-test urine reagent strips by analysis of contrived urine specimens, testing accuracy, precision, specificity, and limits of detection of both products. Relative cost and ease of use were also examined. Each brand of urinary dipstick had specific advantages but it is unlikely that patient care would be adversely affected by preferential use of either product.
Immunoelectrophoretic quantitation of alpha-fetoprotein.
Authors: Pietrogrande M , Roffi L , Bassi A S , Vergani C
Published: January 2020

We describe an immunoelectrophoretic method for alpha-fetoprotein quantitation. The sensitivity of the method, which is easy to perform in the routine laboratory, is under the best conditions 50 mug/liter, but 83 mug/liter can always be detected. With this test, sera from patients with various hepatic diseases and from pregnancies can be tested.
Interconverting measurements of human lactate dehydrogenase activities in three buffers.
Authors: Buhl S N , Richards A H , Jackson K Y , Lubinski R , Vanderlinde R E
Published: January 2020

The lactate-to-pyruvate reaction for serum lactate dehydrogenase (LD) is most frequently assayed in one of three buffers, pyrophosphate (PPi), tris(hydroxymethyl)amino-methane (Tris), or 2-amino-2-methyl-1-propanol (AMP). We described interconverting results for serum samples and for highly purified LD isoenzymes I (dissolved in one of these matrixes) assayed in these buffers under optimized reaction conditions. The equation for converting results obtained for sera in Tris (x) to those in PPi(y) (both at 30 degrees C) is y = 0.74x+10 (n = 98). Since AMP is used extensively in Technicon procedures, we determined the LD activity of sera with an SMA 12/60, at 37 degrees C. The equation for convering these AMP results to results obtained in PPi at 30 degrees C is y = 0.45x-16 (n = 90). Very different equations were obtained with highly purified LD isoenzyme I maintained in two different matrixes and with both isoenzymes assayed in the same matrix. The matrix in which LD is dissolved and the proportion of various LD isoenzymes affect the magnitude of difference in observed LD activity under various conditions. Therefore, in clinical laboratories that use more than one analytical method or when conversion equations are used in the comparison of interlaboratory results, it is important to define the LD source, isoenzyme content, and the matrix, as well as the reaction conditions, and to use many samples with a wide range of activities when determining the conversion equations. For any changes in reagent source, substrate concentration, or alteration in procedure, a new normal range and new conversion equations should be determined.
Evaluation of current methods for creatine kinase isoenzyme fractionation.
Authors: Morin L G
Published: January 2020

I have evaluated electrophoretic, ion-exchange, kinetic, selective activation, and immunological methods of fractionating creatine kinase isoenzymes for diagnostic purposes. The last three were unsuitable. Electrophoretic methods had superior resolution and reliability, but were relatively insensitive when conventional film-drying techniques were used. With elution from the film, sensitivity was comparable to that of the ion-exchange methods. Electrophoretic methods require more skill than the other methods. Ion-exchange methods had acceptable resolution and reliability with potentially superior sensitivity; they require less skill than electrophoresis, but require about as much time. Batch operation of ion-exchange yielded superior efficiency and sensitivity, and was otherwise comparable to column operation.
Ultraviolet spectrometry of serum triglycerides by a totally enzymic method adapted to a centrifugal analyzer.
Authors: Wakayama J E , Swanson J R
Published: January 2020

We described a micromethod for determining serum triglycerides (triacylglycerols) with the centrifugal analyzer. This technique is based on the procedure of Bublitz and Kennedy [J. Biol. Chem. 211, 951 (1954)]. The enzymic hydrolysis requires 10 min at 30 degrees C. Twenty-six serum triglyceride assays can be done in about 30 min. Concentration and absorbance are linearly related up to 5.0 mmol/liter, but higher concentrations can be assayed by changing conditions slightly. Day-to-day reproducibility for the method was satisfactory (CV, 2.7 to 8.4%). Comparison of this method and two other methods for triglycerides, the automated Hantzsch condensation method and a commercial enzymic method (Calbiochem), gave correlation coefficients of 0.976 and 0.990, respectively. Results are unaffected by the presence of endogenous serum ADP, pyruvic acid, phosphatases, or ATPase.
Is lead poisoning still a problem?
Authors: Chisolm J J
Published: January 2020

Today, health professionals are concerned about whether asymptomatic or mildly symptomatic increases in lead absorption in preschool children is one of the important factors causing minimal brain dysfunction, which only becomes evident later during the school years. This concern arises, in part, because current screening data show that 5 to 10% of the children tested recently in the United States have a degree of increase in lead absorption sufficient to cause metabolic derangement in heme synthesis, but insufficient, with rare exception, to cause classical acute clinical symptoms of plumbism. These screening data are disturbing because similar increases in lead absorption in suckling (but not older) experimental animals have been shown in some studies to be followed by the delayed appearance of subtle deficits in learning ability and aberrations in behavior. Derangement of hemoglobin synthesis is the first adverse effect of increased lead absorption now detectable. Intervention on the basis of the first or critical effect of a toxic agent before more serious effects occur has advantages from the viewpoint of preventive medicine. Current CDC guidelines for prevention of childhood lead poisoning are based on this concept and recommend the use of micro-scale erythrocyte protoporphyrin tests in conjunction with micro blood lead tests for early detection of children with disturbed heme synthesis caused by lead.
Measurement of serum magnesium with a centrifugal analyzer.
Authors: Khayam-Bashi H , Liu T Z , Walter V
Published: January 2020

We show how serum magnesium can be determined with a centrifugal analyzer. The method is based upon a manual procedure involving magnesium/calmagite complex formation in an alkaline reagent mixture. The assay, performed at 30 degrees C, requires 5 mul of serum in a final reaction volume of 405 mul, including 350 mul of reagent mixture. The stable color produced at 1 min is measured at 520 nm. Linearity studies showed that Beer's law was followed to 50 mg/liter. Average analytical recovery was 97.3%. Within-day studies showed CV's of 3.36% and 1.09%, compared to day-to-day variations of 5.32% and 3.04% at 18.8 and 46.6 mg of magnesium per liter, respectively. Correlation studies with the manual method, the Du Pont aca (methylthymol blue compleximetric) procedure, and atomic absorption spectroscopy showed correlation coefficients of 0.996, 0.976, and 0.950, respectively. Results compare excellently with those by common present methods. The method is fast, economical, reliable, and applicable to small specimen volumes.
Alkaline phosphatase activity in the plasma of children and adolescents.
Authors: Fleisher G A , Eickelberg E S , Elveback L R
Published: January 2020

We determined plasma (serum alkaline phosphatase activity in 854 healthy students of the Rochester, Minnesota, public schools. Prepubertal girls had somewhat greater upper limits than did boys, and there was a low trend of increasing activity in both sexes. At the beginning of adolescence increasing activities were observed, which peaked at ages 11 to 12 years in girls and at ages 13 to 14 in boys. Adult values were not reached until six to eight years later. In 180 pairs of siblings, a significant intraclass correlation was noted. A possible role of alkaline phosphatase in the regulation of protein synthesis is suggested.
Evaluation of a semi-automated blood urea nitrogen analyzer.
Authors: Hanson D J , Bretz N S
Published: January 2020

We compared results for urea concentrations in plasma and serum as measured with the Kimble Blood Urea Nitrogen Analyzer method as the test method with those determined by continuous-flow analysis (AutoAnalyzer 1 method) as the comparison method. We evaluated accuracy and precision for patients' samples, National Bureau of Standards Standard Reference Material, College of American Pathologists Survey Validated Reference Materials, and College of American Pathologists Quality Assurance Service control materials. We found the test method to be more accurate and precise than the comparison method.
Separation of serum creatine kinase isoenzymes by ion-exchange column chromatography.
Authors: Klein B , Foreman J A , Jeunelot C L , Sheehan J E
Published: January 2020

We describe a practical, technically convenient DEAE-Sephadex chromatographic column and a three-fraction salt-gradient elution procedure, with which serum creatine kinase activity is rapidly and quantitatively separated into the isoenzyme components with excellent analytical recovery of the total activity applied. The homogeneity of the isoenzyme fractions was demonstrated by electrophoresis and rechromatography. Sera assessed by the Mercer fractionation [Clin. Chem. 20, 36 (1974)] and the present procedure showed excellent agreement.
Spectrofluorometry of free and protein-bound plasma tryptophan.
Authors: Woo J , Cano C , Cannon D C
Published: January 2020

We report a rapid, simple, and sensitive spectrofluorometric procedure for total serum or plasma tryptophan. Plasma deproteinization, tryptophan extraction, and pH optimization are all carried out with a buffered cellulose/ethanol reagent. The fluorescence is measured at an emission wavelength of 350 nm, on excitation of 290 nm. Tryptophan fluorescence relative to concentration is linear up to 50 mg/liter. The high precision, evidenced by a between-run coefficient of variation of 3.1%, negates the need for duplicate analysis of samples. Analytical recovery of tryptophan from plasma up to 50 mg/liter is 90-100%. We observed no significant difference between values for tryptophan in serum and plasma from the same individual. Assay of up to 32 samples requires 60 min. Commonly used anti-depressants have no detectable effect on tryptophan determination by this procedure.