bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of acetate in human blood by gas chromatography: effects of sample preparation, feeding, and various diseases.
Authors: Tollinger C D , Vreman H J , Weiner M W
Published: January 2020

We measured acetate concentrations in whole blood, serum, and plasma by a modification of a previously described method involving vacuum distillation and gas chromatography. The mean acetate concentration of fresh venous plasma from 27 normal subjects was 51 +/- 5 mumol/L (95% confidence limits ranged from 0 to 103 mumol/L). The acetate concentrations of serum and plasma incubated for 2 h at either 4 degrees C or 27 degrees C were the same. The acetate concentration of whole blood incubated at 27 degrees C was significantly greater than that of blood incubated at 4 degrees C. This change may have resulted from the production of acetate by erythrocytes or from the hydrolysis of acetate esters. Storage of plasma at -20 degrees C for 24 h significantly increased acetate concentrations from 26 +/- 6 mumol/L to 63 +/- 4 mumol/L. After the subjects consumed a standard breakfast, venous plasma acetate concentrations increased from 58 to 97 mumol/L at 30 min. Acetate concentrations in arterial plasma exceeded those in venous plasma. Plasma acetate concentrations were not significantly altered in patients with malignancy or diabetes mellitus, but severe liver disease and severe acidosis were both associated with increased acetate concentrations. These preliminary observations suggest that plasma acetate concentrations may be altered in several disease states.
Myocardial infarction?--a conflict between electrocardiographic changes and biochemical data.
Authors: Borer W Z , Gottdiener J S , Papadopoulos N M
Published: January 2020

We present a case of hypovolemic shock accompanied by electrocardiographic changes classically associated with acute myocardial infarction. Prompt therapeutic intervention, which included correction of the hypovolemic shock, resulted in stabilization of the patient's clinical course, increased activities of the cardiac-specific enzymes in serum were not documented. Serial electrophoretic determinations of the isoenzymes of serum lactate dehydrogenase did not show the characteristic changes associated with myocardial infarction. Accurate determination of the serum isoenzymes provided valuable diagnostic information which, accompanied by the patient's clinical improvement, militated strongly against the occurrence of myocardial infarction.
Determination of ammonia and urea in urine and of urea in blood by use of an ammonia-selective electrode.
Authors: Georges J
Published: January 2020

I propose a single, quick method for measuring ammonia in urine and urea in plasma and urine. An ammonia-selective electrodie is used, set up on a microcell, which allows use of small sample volumes. Ammonia is measured directly after partial conversion of ammonium ions to NH3. Urea is measured after its hydrolysis by urease. With urine, the two procedures can be carried out successively in the same cell and on the same sample without changing the procedural conditions. Linear electrode response and accuracy have been checked for concentrations in the expected (normal) range.
Disopyramide determination by gas chromatography, liquid chromatography, and gas chromatography--mass spectrometry.
Authors: Vasiliades J , Owens C , Ragusa F
Published: January 2020

Disopyramide is determined in serum by gas chromatography with a nitrogen-selective detector, by liquid chromatography, and by gas chromatography--mass spectrometry. Comparable results are obtained with the three techniques, with a within-run and between-run precision of 5 to 10% (coefficient of variation). Least-squares analysis of data on patients' sera, analyzed first by gas chromatography (y) and then liquid chromatography (x), gave a slope of 1.12; y-intercept, -0.31; standard error of estimate, 0.46; and correlation coefficient, 0.94. Comparison of patients' sera by gas chromatography (y) and then by gas chromatography--mass spectrometry (x) gave a slope of 0.94; y-intercept, 0.42; standard error of estimate, 0.38; and correlation coefficient, 0.97. Interferences observed when using one technique--for example, gas chromatography--can be eliminated by analyzing the sample extract with one of the other techniques.
Quantitation of hemoglobin A1a+b and hemoglobin A1c by automated "high-performance" liquid chromatography.
Authors: Gruber C A , Koets M D
Published: January 2020

The glycosylated hemoglobins A1a+b and A1c have been rapidly and precisely quantitated in 5-micro L samples of human blood hemolysate (approximately 240 micrograms of hemoglobin) by cation-exchange column chromatography. Total chromatographic is 22.0 min. Proportions of Hb A1c range from 3.85 to 6.71% in normal individuals and from 4.23 to 19.90% in diabetic subjects. Within-day variation was 1.58 and 1.10% for mean Hb A1c proportions of 4.92 and 10.32%, respectively. Hb A1c and Hb A1 are stable in hemolysates stored at 4 degrees C for as long as seven days, and indefinitely under liquid nitrogen.
Cryoactivation of renin in plasma from pregnant and nonpregnant subjects, and its control.
Authors: Rowe J , Gallery E D , Györy A Z
Published: January 2020

Plasma renin activity increased by a mean of 7% from baseline values when blood from nonpregnant persons was kept at 0 degrees C for 5 h before incubation. Freezing chilled plasma and thawing it before incubation resulted in a mean increase of 11%. The same procedures used on plasma from normal pregnant women produced mean increases in plasma renin activity of 44 and 89%, respectively. If blood from pregnant women was kept at 0 degrees C for 5 h, and the plasma then separated, frozen, and thawed before incubation, the resulting mean increase in plasma renin activity from baseline values was 160%. We conclude that plasma from pregnant women should be handled at room temperature, or, if samples must be stored, they must be rapidly frozen, then thawed as rapidly as possible before incubation and assay if results are to be reproducible.
Effects of contaminant radioactivity on results of 125I-radioligand assay.
Authors: Witherspoon L R , Shuler S E , Garcia M M , Zollinger L A
Published: January 2020

Diagnostic radionuclide imaging procedures are often used in patients whose sera are later assayed by use of 125I-labeled radioligands; thus, it is important to identify those assays that potentially may be affected by contaminating radioactivity. Results obtained with assays in which specific separation methods (solid-phase primary antibody, second antibody) or small (10--25 micdo L) sample volumes are used are little affected by the presence of such contaminating radioactivity. Less-specific techniques (polyethylene glycol, charcoal, ion-exchange resin) segregate some of the contaminant activity into the bound fraction. The degree to which such activity is protein bound and the concentration of endogenous ligand then contribute to the resulting error in dose estimation. Samples for these assays should be screened for radioactivity before the assay is begun. Inclusion of nonspecific binding tubes for patients' samples when contamination is present permits the contaminating radioactivity to be evaluated and the patient's dose concentration to be more accurately estimated.
Centrifugal analyzer method for total bilirubin in serum by use of diazotized 2-chloroaniline-5-sulfonic acid.
Authors: Brody J P , Valdes R , Savory J
Published: January 2020

We describe two centrifugal analyzer methods for measuring total bilirubin in serum. Diazotized 2-chloroaniline-5-sulfonic acid is used in both. In the first procedure, ethylene glycol and methanol are used as an accelerator solvent; results correlate well with those by a Jendrassik and Grof method adapted to the centrifugal analyzer, but there is considerable hemolysis interference. In the second method, dimethyl sulfoxide is used with the ethylene glycol/methanol solvent and almost all hemolysis interference is eliminated. For either method, a 15-microliter sample is required. In the second method, instrument response is linearly related to concentration to 250 mg/L and the within-run precision (CV) is about 1%.
Gas-liquid chromatographic determination of mono- and diiodotyrosines in serum.
Authors: Davis L G , Sass N L , Manna B , Nusynowitz M L
Published: January 2020

A sensitivie, reliable gas-chromatographic assay for monoiodotyrosine and diiodotyrosine in human serum is reported. The oxazolidinone-heptafluorobutyric anhydride derivatives allow the quantitation of both compounds in the linear range of 0.2 to 7.6 mg/L of serum. Analytical recovery averaged 88%, and mean accuracy and within-run precision were 98 and 2%, respectively. Concentrations of monoiodotyrosine in serum as low as 20 microgram/L and of diiodotyrosine as low as 100 microgram/L can be detected. Normal serum contains no detectable concentration of either compound, but the method is applicable as a diagnostic tool in the early prediction of thyroid disease. Both compounds were detected in the serum of a hypothyroid subject whose normal thyroid hormone concentrations were being maintained by therapy with desiccated thyroid extract.
Reversed-phase liquid chromatographic separation of 3',5'-cyclic ribonucleotides.
Authors: Krstulovic A M , Hartwick R A , Brown P R
Published: January 2020

A rapid, reversed-phase "high-performance" liquid-chromatographic separation of the five naturally occurring cyclic ribonucleotides is described. The separation, optimized for the measurement of these compounds in biological samples, is short (25 min), sensitive (50-100 pmol), and requires no sample pre-concentration steps. We also report an alternative isocratic elution mode, optimized for a rapid and selective analysis for adenosine 3',5'-cyclic phosphate. The identity of chromatographic peaks in biological extracts is confirmed by several methods: retention times, co-chromatography with the reference compounds, absorbance ratios, enzymatic peak-shift with cyclic nucleotide phosphodiesterase, and stopped-flow ultraviolet-scanning techniques.
Four kits for plasma digoxin radioimmunoassay compared.
Authors: Bergdahl B , Molin L , Lindwall L , Dahlström G , Scherling I L , Bertler A
Published: January 2020

We evaluated four commercial radioimmunoassay kits for digoxin. We assayed a standard plasma containing digoxin, 2.0 microgram/L, and samples from patients receiving digoxin, with use of the kits and of a bioassay, the 86Rb-uptake inhibition technique. Intra-assay precisions differed significantly. Computer-calculated 95% confidence intervals for the radioimmunoassays averaged 0.4 to 0.6 microgram/L at the proposed toxic threshold of 2.0 microgram/L; the corresponding value of the 86Rb assay was 0.75 microgram/L. Digoxin in the standard plasma was overestimated with three of the kits (means: 2.40, 2.56, and 2.59 microgram/L) but was assayed accurately by the 86Rb technique and by one kit. This same kit gave a significantly lower mean (1.07 microgram/L) for the patients' samples then did the other three kits (1.32, 1.49, and 1.29 microgram/L), two of which also differed significantly in accuracy. The 86Rb assay measured glycoside activity corresponding to a mean digoxin concentration of 1.35 microgram/L. We conclude that the relatively low precision of digoxin assay and the variations in accuracy between kits from various vendors apparently deserve continual attention.
Gas-chromatographic determination of disopyramide in serum, with use of a nitrogen-selective detector.
Authors: Vasiliades J , Owens C , Pirkle D
Published: January 2020

In this procedure for disopyramide in serum, the drug is extracted into n-heptane/isobutanol (96/4 by vol), then back-extracted into 1 mol/L H2SO4. The acidic solution is made basic with sodium hydroxide, extracted with diethyl ether, and the extract evaporated. The residue is redissolved in ethanol and analyzed by gas-chromatography, with use of a nitrogen-selective detector. p-Chlorodisopyramide is used as internal standard. Concentration and instrument response for serum extracts are linearly related from 1 to 5 mg/L, the slope being 0.61, the y-intercept -0.10, the standard error of estimate 0.01, and the correlation coefficient 0.99. Within-run precision was 6 and 4% for 3 and 5 mg/L concentrations, respectively, with a between-run precision of 7% at the 3 mg/L concentration. Diazepam interferes, but procainamide, chlordiazepoxide, quinidine, lidocaine, propranolol, sulfanilamide, and many other basic drugs do not.
Erythrocyte enzyme deficiencies assessed with a miniature centrifugal analyzer.
Authors: Fielek S , Mohrenweiser H W
Published: January 2020

Methods for assaying 16 erythrocyte enzymes have been adapted to the miniature centrifugal analyzer. Less than 15 micro L of whole blood is required for all 16 assays. Variation attributable to temporal effects, rotor effects, and random residual error is minor. Initial population studies of blood from adults and cord-blood samples suggest a CV of less than 12% for 12 of the 16 enzymes; thus it should be possible to identify the heterozygous deficient individual. Preliminary data suggest that three such individuals, with enzyme activity (adenylate kinase, pyruvate kinase, phosphoglycerate kinase) about half the expected, have been identified, as well as two individuals deficient in glucose-6-phosphate dehydrogenase.
Comparison of interlaboratory results for blood lead with results from a definitive method.
Authors: Boone J , Hearn T , Lewis S
Published: January 2020

Results reported by 113 participants in the Blood Lead Proficiency Testing Program conducted by the Center for Disease Control were compared with those obtained by the National Bureau of Standards (NBS) with a definitive methods (mass spectroscopy-isotopic dilution) for blood lead analyses. Data were compiled from the results obtained for 12 whole-blood samples containing 1.5 g of disodium EDTA per liter. Twelve separate blood samples were obtained from cattle which had been given lead nitrate orally. Lead concentrations in the samples ranged from 0.628 to 4.93 mumol/L (130-1020 micrograms/L) as determined by NBS. The methods used by laboratories were classified according to six basic groups: anodic stripping voltametry; and atomic absorption spectroscopy in which either extraction, carbon rod, graphite furnace, tantalum strip, or Delves cup was used. For results obtained in each group a linear regression analyses of laboratory values was made on the basis of NBS values. In comparison to the definitive method, most field methods for blood lead tended to overestimate the lead concentration when the actual lead concentration was less than 1.96 mumol/L (400 micrograms/L) and to underestimate the lead concentration when the actual lead concentration was greater than 2.45 mumol/L (500 micrograms/L).
Liquid-chromatographic analysis for methylphenidate (Ritalin) in serum.
Authors: Soldin S J , Chan Y P , Hill B M , Swanson J M
Published: January 2020

We describe a "high performance" liquid chromatographic method for quantitating methylphenidate in serum. The internal standard, 4,5-diphenylimidazole, and serum or plasma sample are extracted in chloroform, evaporated, and redissolved in 20 mmol/L potassium phosphate (pH 3.5)/high-purity acetonitrile, 80/20 by vol. A centrifuged aliquot is chromatographed on mu-Bondapak C-18 with the phosphate/acetonitrile solvent as mobile phase, a flow rate of 1.6 mL/min, and a column temperature of 40 degrees C. Absorbances are read at 192 nm. This method reliably measures concentrations greater than 20 micrograms/L and has analytical recoveries of 74%.
Macro creatine kinase BB in serum, and some data on its prevalence.
Authors: Urdal P , Landaas S
Published: January 2020

We report the case of a patient with persistently above-normal activity of creatine kinase (CK) in serum, a major fraction of which on electrophoresis moved as a band between the MM and MB isoenzymes and on anion-exchange column chromatography eluted in the MB fraction. Measurements in the presence of specific M or B subunit-inhibitory antibodies indicated that 93% of the activity consisted of B-isomers. From these experiments we conclude that the abnormal CK is of BB nature. Gel filtration and immunoglobulin precipitation showed that the CK-BB was complexed with IgG. Normal CK-BB, when mixed with the patient's serum, was converted to macro CK-BB. In vitro stability of 37 degrees C of the abnormal enzyme was much greater than that of normal BB and MM isoenzymes. Following this finding, we then assessed 310 sera, received for enzyme assay by the clinical laboratory, for electrophoretically abnormally migrating CK isoenzymes. Of these, five (1.6%) contained such enzymes, all being of BB nature. They were of increased molecular mass, and at least three of them were complexed with IgG.
Manual fluorometry of phenylalanine from blood specimens collected on filter paper: a modified procedure.
Authors: Wu J T , Wu L H , Ziter F A , Ash K O
Published: January 2020

In this manual fluorometric method, blood samples are used that have been impregnated on the filter paper, a convenient collection technique that is widely used to screen newborns for phenylketonuria. The modified procedure, based on the method of McCaman and Robins [J. Lab Clin. Med. 59, 885 (1962)], includes elution of phenylalanine from specimens on filter paper, removal of proteins by precipitation with trichloroacetic acid at 0 degrees C, and then reaction with ninhydrin-peptide reagent for color development. The standard curve is linear to at least 200 mg/L and the CV is 6.3% for a phenylalanine concentration of 27 mg/L. The modified procedure is suitable both for early screening for phenylketonuria and for monitoring blood phenylalanine of phenylketonurics during dietary therapy.
Concentrations of ionic, total, and bound fluoride in plasma.
Authors: Singer L , Ophaug R H
Published: January 2020

We found no significant difference between the means for ionic, bound, and total fluoride concentrations in the plasma of male and female subjects of the same age, living in a community with fluoridated water. When results for the 264 fasting subjects were therefore combined according to age, they indicated that persons over 60 years of age have a significantly higher mean ionic (3.89 mumol/L) and total (6.58 mumol/L) fluoride concentration in plasma than do younger age groups. For younger age groups, means ranged from 2.74 to 3.05 mumol/L for ionic fluoride and from 4.74 to 5.58 mumol/L for total. The bound fluoride concentration was lower in individuals 21 to 30 years of age (1.89 mumol/L) than in older age groups (for whom means ranged from 2.42 to 2.68 mumol/L), but was not significantly different from that of individuals who were younger (2.21 mumol/L). A tendency for the mean ionic fluoride concentration to increase with age was noted, but the concentration was significantly higher than the preceding decade group only in those persons over 60 years of age.
Preservation, distribution, and assay of glucose in blood, with special reference to the newborn.
Authors: Meites S , Saniel-Banrey K
Published: January 2020

Of several preservatives we tested, a mixture of "isotonic" sodium fluoride and sodium iodoacetate (17.7 and 5.0 g/L, respectively) best inhibits glucose loss from blood collected from the newborn. However, the inhibition is incomplete. Twenty microliters of blood is diluted with 100 microliter of preserving solution. After centrifugation, the glucose in 100 microliter of prewarmed supernate (diluted plasma) is measured in a Beckman Glucose Analyzer, based on the action of a glucose reagent and the rate of oxygen consumption. The method, in effect, determines the glucose in whole blood, except for about 5% of the total that remains in the erythrocytes. Glucose is distributed in blood according to the water content of cells and plasma. From concentrations found in cells and plasma, we can calculate the value for glucose in whole blood with an accuracy of 95.2%. The modified method we describe shows acceptable precision, as judged from within-run and day-to-day CV--generally well below 5% for each.
Further observations on the incidence and nature of atypical creatine kinase activity.
Authors: Sax S M , Moore J J , Giegel J L , Welsh M
Published: January 2020

The interference of atypical creatine kinase (CK; EC 2.7.3.2) with anion-exchange methods for the measurement of the CK-MB isoenzyme is now firmly established. False-positive results from this source are much more common than interferences caused by the BB isoenzyme. Atypical CK, at least in some patients, does not appear to be a genetic variant, nor could we relate it to a specific clinical diagnosis, to hypoxia, or to administration of a particular drug. Its behavior in an immuno-inhibition test for CK-B subunit indicates an immunological difference from the normal M subunit. Thus the change in immunological properties is associated with the altered electrophoretic properties. The variability of electrophoretic patterns suggests that atypical CK may represent multiple forms of creatine kinase rather than a unique entity.
Liquid-chromatographic assay for urinary 3-methoxy-4-hydroxymandelic acid, with use of a periodate oxidative monitor.
Authors: Rosano T G , Brown H H
Published: January 2020

We describe a "high-performance" liquid-chromatographic procedure for measuring 3-methoxy-4-hydroxymandelic acid (vanillylmandelic acid) in urine. The compound is quantitatively extracted from urine by use of an automated system, including an anion-exchange resin. After elution from the resin and concentration by air drying, the urine extract is chromatographed on an octyl silica column, with use of a buffered mobile phase. To overcome interference from other organic acid in the extract, the column effluent is reacted with periodate in an analytical system to oxidize the analyte and internal standard to products that absorb at 360 nm. We evaluated the procedure for precision, linearity, analytical recovery, interfering substances, and correlation with an established procedure. The combination of a preliminary resin extraction, a liquid-chromatographic separation, and a periodate oxidative monitor results in a rapid, specific method that can be adapted for use in the clinical laboratory.
New fluorometric analysis for mandelic and phenylglyoxylic acids in urine as an index to styrene exposure.
Authors: Chakrabarti S K
Published: January 2020

I describe a new fluorometric method for determination of mandelic and phenylglyoxylic acids in urine, the fluorometry being preceded by extraction into ether and thin-layer chromatography. The chromatographically separated acids were quantitated after conversion to stable highly fluorescent derivatives by treatment with concentrated sulfuric acid. This method proves to be more precise, accurate, and reproducible than the existing colorimetric method. The limit of detection is 2 microgram of either acid per milliliter of urine with a CV of less than 15%. The standard curve for either acid is essentially linear from 2 to 100 microgram/mL of urine, with a correlation coefficient (r) of 0.97. No satisfactory correlation was obtained between the concentrations of either acid metabolite as measured in rat urine by fluorometry and colorimetry. The present method is considered suitable for routine biological monitoring of persons exposed to both high and low concentrations of styrene.
Improved automated kinetic determination of uric acid in serum by use of uricase/catalase/aldehyde dehydrogenase.
Authors: Bartl K , Brandhuber M , Ziegenhorn J
Published: January 2020

The enzymatic determination of serum uric acid by use of uricase, catalase, and aldehyde dehydrogenase according to Haeckel [J. Clin. Chem. Clin Biochem. 14, 101 (1976)] showed interferences from ethanol-converting enzymes, which are present in some patients' sera. We have identified these enzymes as alcohol dehydrogenase isoenzymes. Among other substances, a mixture of pyrazole and oxalate can be used to eliminate these interferences. This inhibitor system gives good results when used in the automated kinetic uric acid determination, as is shown by a comparison with the manual assay for uric acid according to Kageyama [Clin. Chim. Acta 31, 421 (1971)].
Effect of light and temperature on the stability of creatine kinase in human sera and controls.
Authors: Perry B , Doumas B , Jendrzejczak B
Published: January 2020

Commercial control preparations were exposed to light at room temperature for as long as 24 h. Decreases in creatine kinase activity in seven of the nine controls ranged from 28.8 to 83.3%. When these controls were protected from light and stored at various temperatures, the decrease in activity was either eliminated or substantially reduced, indicating that the decreased activity in the presence of light was not due entirely to thermal inactivation. In the absence of oxygen, light had little effect on creatine kinase suggesting that light inactivation is a light-catalyzed oxidative process. The decreased activity observed when some of the controls were exposed to light was not completely restored by incubating with dithiothreitol before analysis. However, increases in creatine kinase activity ranging from about 37 to 176% were observed when freshly prepared controls were pre-incubated with dithiothreitol. Neither light nor dithiothreitol had any effect on the creatine kinase activity in two of the nine controls. When human sera were exposed to light for 24 h, the largest decrease in activity was about 15%. Incubation of fresh human sera with dithiothreitol before analysis caused an average increase in activity of approximately 10%.
Elemental composition of platelets. Part I. Sampling and sample preparation of platelets for trace-element analysis.
Authors: Iyengar G V , Borberg H , Kasperek K , Kiem J , Siegers M , Feinendegen L E , Gross R
Published: January 2020

Sampling of platelets for trace-element analysis poses special problems: obtaining adequate sample material, achieving a sufficient cell purity, preserving viability (integrity), correcting for trapped plasma, and controlling contamination. We used a blood-cell separator for the primary isolation of platelets from blood, and differential centrifugation in natural plasma to further isolate them. The pyrimidopyrimidine RA233 was used as a stabilizer to maintain viability. 131I-labeled human serum albumin was used to estimate trapped plasma. Contamination was controlled by using five-times-distilled water to simulate donor's blood in the system and by comparing three fractions: the serum, the first portion of the platelet-rich plasma, and the supernatant plasma after the final centrifugation. Neutron activation analysis was used for the elemental analysis. A single differential centrifugation of the platelet-rich plasma from the blood-cell separator at 400 x g for 8 min was optimum (mean mass fractions:erythrocytes/platelets less than 5 mg/g and leukocytes/platelets less than 20 mg/g). The trapped plasma in the wet platelet samples amounted to about 0.40 g/g. No appreciable contamination from the sampling system was found for the elements Ag, Cd, Co, Cr, Cs, Cu, Fe, Mo, Rb, Sb, Se, and Zn.
Significance of "high" acid phosphatase activity in the serum of normal children.
Authors: Chen J , Yam L T , Janckila A J , Li C Y , Lam W K
Published: January 2020

Serum acid phosphatase activity in normal children (newborn to 18 years) is several fold that in normal adults. Activity is age-related but not sex-related. The isoenzyme pattern in children is similar to that in adults and contains no prostatic fraction. Quantitatively, most of the enzyme activity in the serum of children is tartrate-resistant and correlates well with heat-labile fractions of alkaline phosphatase activity in serum, suggesting that the source of the higher acid phosphatase activity in children is bone. Significant tartrate-resistant acid phosphatase activity was demonstrated in the giant cells in three patients with giant-cell tumors, but not in the "osteoblasts" in six patients with osteogenic sarcomas and many other normal or abnormal tissues. This work suggests that the higher enzyme activity in the serum of children represents a normal physiological phenomenon resulting from their greater osteoclastic activity.
Glycosylated hemoglobin assay and oral glucose tolerance test compared for detection of diabetes mellitus.
Authors: Dods R F , Bolmey C
Published: January 2020

We compared the oral glucose tolerance test (I) as evaluated by six commonly used scoring methods and total glycohemoglobin assay (II) with respect to their value in the diagnosis of diabetes mellitus. Depending on the evaluation method used for I, 16.7 to 64.3% of those subjects diagnosed as diabetic or borderline by this test were judged to be normal by II. The best agreement was between II and the Unger evaluation method. High-density-lipoprotein cholesterol, which showed an inverse correlation with II, was decreased in subjects judged to be diabetic by the Unger method. We conclude that the utilization of II measurement as a screening method for diabetes mellitus is consistent with a conservative approach to the diagnosis of diabetes.
Extraction of human plasma or sera by heat treatment for a solid-phase radioimmunoassay of carcinoembryonic antigen.
Authors: Kim Y D , Tomita J T , Schenck J R , Moeller C , Weber G F , Hirata A A
Published: January 2020

Heat treatment and a solid-phase radioimmunoassay are combined to give a relatively simple and rapid procedure for assay of carcinoembryonic antigen in plasma or serum. The new way we describe to extract this antigen is an alternative to the conventional method of extraction with perchloric acid. Heating plasma or serum samples in acetate buffer (0.16 mol/L, pH 5.0) at 70 degrees C for 15 min precipitates out most of the heat-labile, nonspecific plasma proteins, but leaves most of the antigen in solution, with its immunochemical properties apparently unaffected. Comparison between the heat treatment and the perchloric acid extraction yielded comparable values when tested either by solid-phase radioimmunoassay or by the zirconyl phosphate precipitation method. An added advantage of our method is that it gives the same assay values for both plasma and serum. Results for a group of pathological plasma samples, assayed by both our method and the perchloric acid-zirconyl phosphate precipitation method, gave a correlation coefficient of 0.90.
Alanine aminotransferase and aspartate aminotransferase measurements with two automated analyzers, SMAC and the ABA-100, compared.
Authors: Purcell G V , Behenna D B , Walsh P R
Published: January 2020

Measurements of alanine aminotransferase and aspartate aminotransferase with the SMAC were evaluated for correlation with the ABA-100, precision, linearity, and carryover. We assayed 200 specimens with normal and abnormal aminotransferase activities with both the SMAC (y) and the ABA-100 (X). Linear regression analysis of the data yielded the following: alanine aminotransferase (r = 0.9732, y = 0.96x + 3.8); and aspartate aminotransferase (r = 0.9892, y = 0.90x + 2.1). Both aminotransferases demonstrated acceptable intra- and inter-assay variations with the SMAC and ABA-100. With the SMAC the upper limit of linearity for alanine aminotransferase was 350 U/L; that for asparate aminotransferase was 450 U/L. Carryover studies for SMAC indicate that specimens immediately following specimens with alanine aminotransferase activities greater 400 U/L and (or) aspartate aminotransferase activities greater than 500 U/L should be re-analyzed.
Simplified immunonephelometric quantitation of apolipoprotein B in hyperlipoproteinemic serum.
Authors: Heuck C C , Schlierf G
Published: January 2020

An immunonephelometric procedure for determination of apolipoprotein B in human serum [Clin. Chem, 25, 221-226 (1979)] was modified by using the detergent octadecenylamine-polyoxyethylene, which may bind selectively to the phospholipid moiety of lipoproteins. Preincubation of hyperlipemic serum samples with lipases could then be omitted.
Assessment of fetal lung maturity by colorimetric phospholipid determination without digestion.
Authors: Worth H G , Wright D J
Published: January 2020

A previously described method for the determination of phospholipid concentration in amniotic fluid without digestion has been modified to make it more suitable for use in a routine laboratory. Results compare well with those by the original procedure. Results from nearly 70 amniotic fluids, collected at delivery, were compared with lecithin/sphingomyelin (L/S) ratios determined on the same fluids. Statistical analysis of these data showed that for the prediction of lung immaturity, determination of total phospholipid concentration was at least as good as the L/S ratio.
Evaluation of the Beckman creatinine analyzer.
Authors: Hicks J M , Iosefsohn M , Lewis S A
Published: January 2020

We compared results obtained with the Beckman Creatinine Analyzer (Beckman Instruments, Inc.) to those with the GEMSAEC Centrifugal Analyzer (Electro-Nucleonics, Inc.) and with a manual method for determination of creatinine in serum and urine. Linearity, stability, recovery, and precision were evaluated. Interference from bilirubin, protein, lipemia, uric acid, and hemolysis is negligible, but acetone and acetoacetate can interfere.
Liquid-chromatographic assay of diazepam and its major metabolites in plasma.
Authors: MacKichan J J , Jusko W J , Duffner P K , Cohen M E
Published: January 2020

We describe a method for simultaneous quantitation of diazepam and its metabolites, N-desmethyldiazepam and oxazepam, by reversed-phase liquid chromatography with ultraviolet detection at 254 nm. After extraction with chloroform at pH 11.0, the organic extract is evaporated, and the residue is reconstituted in a small volume of mobile-phase and chromatographed. Concentrations as low as 12 to 20 microgram/L can be detected after extraction of only 250 microL of plasma. The maximum within-day and day-to-day coefficients of variation for each compound at concentrations of 50, 250, and 1000 microgram/L are 8.0 and 10.3%, respectively. Of 14 commonly used anticonvulsant, sedative, and psychotherapeutic drugs, only carbamazepine and lorazepam may interfere with analysis for oxazepam or N-desmethyldiazepam, or both. Total chromatography time for a single sample is less than 10 min. Applicability of the method to diazepam disposition studies in children is illustrated.
Power functions for statistical control rules.
Authors: Westgard J O , Groth T
Published: January 2020

We have studied power functions for several control rules by use of a computer simulation program. These power functions show the relationship between the probability for rejection and the size of the analytical errors that are to be detected. They allow some assessment of the quality available from present statistical control systems and provide some guidance in the selection of control rules and numbers of control observations when new control systems are designed.
A direct radioimmunoassay of serum cortisol with in-house 125I-tracer and preconjugated double antibody.
Authors: Wong P Y , Mee A V , Ho F F
Published: January 2020

We describe a radioimmunoassay of serum cortisol in which 125I-tracer and preconjugated double antibody are used. This simpler method involves direct serum assay, and the majority of reagents are prepared in-house. Within-assay precision (coefficient of variation) of assay of Ortho Diognostic RIA Cortisol I and II was 3.2% (mean = 131 microgram/L, n = 10) and 2.2% (mean = 405 microgram/L, n = 10), respectively. Between-assay precision (coefficient of variation) for the same controls was 6.7% (mean = 128 microgram/L, n = 62) and 5.6% (mean = 395 microgram/L, n = 62), respectivley. By using automatic pipetters and a gamma counter with a data-reduction package, a technologist can complete 100 assays in less than 3 h. The operating cost is approximately 10 cents per tube.
Blood-spot thyrotropin radioimmunoassay in a screening program for congenital hypothyroidism.
Authors: Sadler W A , Lynskey C P
Published: January 2020

We describe a highly sensitive and precise radioimmunoassay for thyrotropin in dried blood spots on filter paper cards. In a screening program for congenital hypothyroidism, blood-spot thyrotropin concentrations are measured in infants whose blood-spot thyroxine concentrations are in the lower 10%, and this strategy has reduced the recall rate from 1.7% (thyroxine assay alone) to 0.17%. Thyrotropin assay samples consist of discs 4.5-mm in diameter, containing about 6 microL of blood, punched from blood spots. By appropriate attention to assay conditions, a mean least-detectable thyrotropin concentration equivalent to 2.5 milliunits/L plasma has been achieved. Concomitant measurement of thyrotropin by plasma and blood-spot assays in 91 subjects yielded a Spearman rank correlation coefficient of 0.9732. An analysis of variance of the distribution volume of thyrotropin in blood spots and a covariance analysis of factors affecting blood-spot thyroxine results are presented.
Determination of high-density lipoproteins: screening methods compared.
Authors: Kostner G M , Avogaro P , Bon G B , Cazzolato G , Quinci G B
Published: January 2020

Factors reflecting the concentration of high-density lipoproteins in serum were assessed for 108 men and 106 women participating in a Venetian screening program for hyperlipoproteinemia. The methods applied, optimized in our laboratory, were: (a) cholesterol in high-density lipoproteins, determined in the supernate after sedimentation of the very-low-density lipoproteins + low-density lipoproteins with dextran sulfate or sodium phosphotungstate; and (b) immunochemical quantitation of apolipoprotein A-I and apolipoprotein A-II by Laurell's "rocket" technique. The latter determinations were performed with total serum before and after delipidation with diispropyl ether/n-butanol (6/4 by vol). The dextran sulfate method gave about 5% higher values than did the phosphotungstate method, but the correlation between the two was excellent (r = 0.95). Results of the immunochemical quantitation indicate that delipidation of lipoproteins before Laurell electrophoresis may not be necessary if only freshly drawn sera are used.
Creatine kinase isoenzymes of mitochondrial origin in human serum.
Authors: James G P , Harrison R L
Published: January 2020

We measured creatine kinase (EC 2.7.3.2) activity in 1009 serum samples from 538 patients in the intensive-care units of the University of Texas Medical Branch hospitals. Creatine kinase isoenzymes migrating cathodal to skeletal muscle creatine kinase (CK-MM) on cellulose acetate electrophoresis were found in sera from 14 of the 538 patients. Creatine kinase, lactate dehydrogenase (EC 1.1.1.27), aspartate aminotransferase (EC 2.6.1.1), and alanine aminotransferase (EC 2.6.1.2) activities were abnormally increased in these 14 patients. Liver lactate dehydrogenase isoenzyme (LDH5) and cardiac creatine kinase isoenzyme (CK-MB) were abnormally increased in 12 and eight of these patients, respectively. Ten of the 14 patients died during their hospital admission. We believe the creatine kinase isoenzymes that migrated cathodal to skeletal muscle creatine kinase (CK-MM) were of mitochondrial origin.
Automated measurement of the elastase-inhibitory capacity of plasma with a centrifugal analyzer.
Authors: Klumpp T , Bieth J G
Published: January 2020

We describe an automated method for measuring the elastase-inhibitory capacity of plasma. We use a GEMSAEC centrifugal analyzer and succinyltrialanine-p-nitroanilide as an elastase substrate. The method is fast (80--100 samples/h) and accurate (CV = 3.6%). The detection limits are from 20 to 300% of the normal value. The elastase-inhibitory capacity is well correlated with the trypsin-inhibitory capacity and with the immunochemically determined concentration of alpha 1-proteinase inhibitor (alpha 1-antitrypsin). Because elastase is not inhibited by other plasma inhibitors, this method can be used as an enzymatic technique for measuring the concentration of plasma alpha 1-proteinase inhibitor. In an apparently normal population, this concentration was 40 +/- 11 mumol/L.
Fluoroimmunoassay for human choriomammotropin.
Authors: Chard T , Sykes A
Published: January 2020

We describe an immunoassay for human choriomammo-tropin by use of the fluorescein-labeled hormone (of human origin). The technique is generally similar to the radioimmunoassay for this material, but has the advantage of stability of tracer and avoidance of radiation hazard. However, the procedure requires approximately 50-fold more tracer than does the radioimmunoassay, and this would be a disadvantage with materials for which supplies of purified antigen are scarce. Furthermore, both within-assay variation (3.9%) and between-assay variation (7.8--7.9%) were less satisfactory than that of radioimmunoassay (1.5% and 2.2--3%, respectively). This is almost certainly the result of imprecision of end-point detection and could probably be corrected by further attention to equipment design.
alpha-Amylase activity by the Beckman reaction system and suppression by pyruvate.
Authors: Hanson N Q , Yasmineh W G
Published: January 2020

We evaluated the new Beckman Enzymatic Amyalse-DS Method with maltotetraose as substrate. Our findings indicate that the method is approximately twice as sensitive as the old method involving soluble starch [Clin. Chem. 24, 762 (1978)]. The new method also shows a linear rate of reaction, in contrast to the curvilinear rate previously observed with the old method. The Km with maltotetraose is 0.77 g/L, or about twice that with soluble starch (0.42 g/L). The method correlates well with the Phadebas alpha-amylase method (r = 0.974 and 0.991 on 84 serum and 52 urine specimens, respectively). Of 43 specimens with high concentrations of pyruvate we examined for interference with alpha-amylase activity, only six showed interference when maltotetraose was the substrate. (With both Beckman methods the reaction of pyruvate with NADH produced lactate and NAD+ in the presence of lactate dehydrogenase as contaminant.) Pyruvate interference decreased with increases in (a) the alpha-amylase activity of the specimen, (b) the amount of NADH initially present in the maltotetraose reagent, and (c) the length of time the reconstituted maltotetroase reagent was allowed to stand before being used.
Chemical assay, involving liquid chromatography, for aminoglycoside antibiotics in serum.
Authors: Bäck S E , Nilsson-Ehle I , Nilsson-Ehle P
Published: January 2020

We describe a chemical assay involving "high-pressure" liquid chromatography for the quantitative determination of three aminoglycosides: netilmicin, tobramycin, and gentamicin. The drugs are separated from serum by means of precipitation of the serum proteins with acetonitrile after dilution with a buffer. The aminoglycosides are quantitatively extracted into the supernate, which is further purified by a two-step partition procedure involving derivatization of the drugs with o-phthalaldehyde. The drug derivatives are separated by reversed-phase chromatography and detected by on-line fluorometry. Sensitivity is 1 mg/L for tobramycin and 0.5 mg/L for netilmicin and gentamicin. Intra- and interassay variation was below 8%. Analytical recovery of each of the three drugs was 92 to 100%. Correlation with microbiological and radioimmunological assay methods was good. The assay is rapid (about 30 min), precise, and specific, and seems suitable for use in a routine clinical laboratory.
Variation in values for iodothyronine hormones, thyrotropin, and thyroxine-binding globulin in normal umbilical-cord serum with season and duration of storage.
Authors: Oddie T H , Klein A H , Foley T P , Fisher D A
Published: January 2020

We measured concentrations of thyroxine, triiodothyronine, reverse triiodothyronine, thyroxine-binding globulin, and thyrotropin in pooled samples of cord sera from normal newborns. Sera collected in winter contain significantly (p less than 0.05) higher concentrations of the first tour--14.9, 13.4, 9k9, and 7.5%, respectively--than do sera collected in summer; thyrotropin concentrations are similar in samples collected during winter and summer (p greater than 0.05). With storage, the values for the thyronines and thyrotropin decreased progressively at rates between 0.9 and 5.3% per year; those for thyroxine-binding globulin did not change significantly.
Decreased aminotransferase activity of serum and various tissues in the rat after cefazolin treatment.
Authors: Dhami M S , Drangova R , Farkas R , Balazs T , Feuer G
Published: January 2020

Treatment of rats with cefazolin in vivo significantly suppressed activity of alanine and aspartate aminotransferases in serum and in the liver, brain, kidney, and heart. Simultaneous administration of pyridoxal further reduced enzyme activity except in the liver, where there was no change. Pyridoxal 5'-phosphate partly reversed the decreased enzyme activity in the serum, liver, and kidney, but did not return it to the amount observed in the control animals; enzyme activity remained suppressed in the brain and heart. The effect of cefazolin was dose related, but there was no sex-related difference. In contrast to its action on am-notransferase activity, cefazolin elicited no effect on alkaline phosphatase (pyridoxal-5'-phosphate hydrolase) in serum or on pyruvate carboxylase in the liver, heart, and kidney. Cefazolin exposed to the hepatic microsomal mixed-function oxidase system in vitro was partly converted into metabolites that inhibited serum alanine aminotransferase activity in vitro. The latter inhibition was reversed by the addition of pyridoxal 5'-phosphate.
Gas-chromatographic analysis for valproic acid as phenacyl esters.
Authors: Gupta R N , Eng F , Gupta M L
Published: January 2020

We describe a novel isothermal gas-chromatographic procedure for measuring valproic acid. Plasma, with cyclohexanecarboxylic acid added as internal standard, is selectively extracted with pentane to minimize the extraction of other acidic drugs. To convert carboxylic acids to their phenacyl esters, alpha-bromoacetophenone is added to the organic extract before evaporating the solvent. These esters are relatively less volatile than the acids themselves and the extracting solvent can be removed without any loss of valproic acid or internal standard. The phenacyl esters, when chromatographed on 3% OV-17, produce sharp, well-shaped peaks and show high response for the flame ionization detector. Valproic acid is well separated from the internal standard, from reagents and plasma constituents, and from some commonly prescribed drugs that we examined. When alpha-bromo-p-nitroacetophenone is sued as the derivatizing agent, the resulting nitrophenacyl esters can be analyzed with use of a nitrogen-specific detector.
Development of a stable lipoprotein diluent for use in reconstituting lyophilized human serum for the preparation of clear, hyperlipidemic quality-control materials.
Authors: Proksch G J , Bonderman D P
Published: January 2020

We describe a simple system for the preparation of a hyperlipidemic control serum. Beta- and pre-beta-lipoproteins are removed from the serum and prepared as a stable diluent; the extracted serum is then lyophilized. Upon addition of the lipoprotein diluent, which was observed to contain only liproprotein and sodium bicarbonate, the serum reconstitutes rapidly, usually within 5 min. By a suitable adjustment of the lipoprotein concentration in the diluent, a hyperlipidemic control serum may be produced with desired concentrations of lipids. Because the lipoproteins are not included in the destructive lyophilization step, the resulting product has remarkable clarity, precision, and stability.