bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of homogeneous enzyme immunoassay of serum thyroxine with the Gilford 3500 analyzer.
Authors: Cruse K L
Published: January 2020

I evaluated homogeneous enzyme immunoassay (EMIT) of serum thyroxine with the Gilford 3500 analyzer. The samples are pretreated before quantitation on the Gilford 3500; the procedure thereafter is entirely mechanized. Forty-four samples may be analyzed per run. Precision and accuracy are good, and results correlate well with those by radioimmunoassay.
A bichromatic method for total bilirubin with a CentrifiChem 400.
Authors: Kelly A , McKenna J P , McLelland A , Percy R A , Spooner R J
Published: January 2020

We describe a method for the bichromatic determination of total bilirubin with a CentrifiChem 400 centrifugal analyzer with the Boehringer DPD kit. After reading the blank at 620 nm, we read the test at 550 nm. Because only one rotor is required, the analytical time for bilirubin estimations is halved. The proposed method is no more prone to interference by hemoglobin or turbidity than a conventional approach or a reference continuous-flow method and has performed well over several months of routine use.
Potential clinical applications of derivative and wavelength-modulation spectrometry.
Authors: O'Haver T C
Published: January 2020

Absorption spectrophotometers are now becoming available that can record the first and second derivatives of absorbance with respect to wavelength. The advantages of this technique and its potential application to clinical analysis are discussed.
Fluorescence protection immunoassay: a new homogeneous assay technique.
Authors: Zuk R F , Rowley G L , Ullman E F
Published: January 2020

We describe a "fluorescence protection immunoassay," in which formation of an immune complex of a fluorescer-labeled antigen sterically protects the fluorescer from binding by antibodies to it. Competitive binding of unlabeled antigen by its antibody prevents formation of the fluorescer-labeled antigen immune complex, and allows anti-fluorescein to quench the fluorescence by binding to the fluorescer. This phenomenon is the basis of a new homogeneous assay technique that requires no separation step. The steric exclusion of anti-fluorescein from fluorescein-labeled human IgG immune complexes was altered by changing the molecular dimensions ob both antifluorescein and the immune complex. The assay did not require highly purified fluorescein-labeled human IgG. An assay is demonstrated in which was used a fluorescein-labeled human IgG conjugate containing IgG that was only 10% pure. Measurement of IgG in human serum samples correlated well with results by radial immunodiffusion. The method is applicable to the assay of both proteins and analytes of low molecular mass.
Microencapsulated antibodies in radioimmunoassay. II. Determination of free thyroxine.
Authors: Halpern E P , Bordens R W
Published: January 2020

We describe a method for directly measuring free thyroxine in human serum. Antibody to thyroxine was encapsulated within a semipermeable nylon membrane that excludes substances of relative molecular mass greater than 20,000. The microencapsulated antibody was then presaturated with [125I]thyroxine. Serum incubated with the microcapsules initiated a displacement reaction between free thyroxine and [125I]thyroxine bound to the antibody. The displaced thyroxine was separated from the bound thyroxine by centrifugation and the concentration of free thyroxine determined from a standard curve prepared by use of known amounts of free thyroxine. The within-day coefficient of variation for two control samples was 8.8 and 6.8%; day-to-day precision for the same material was 12.5 and 13.5%. Lipemia, icterus, or hemoglobin had no adverse effect. Interlaboratory evaluation of the procedure revealed no significant difference in mean values for 20 speciments (p greater than 0.05).
Plasma polyamines determined by negative-ion chemical ionization/mass spectrometry.
Authors: Shipe J R , Hunt D F , Savory J
Published: January 2020

We have developed an accurate and highly sensitive gas-chromatographic/mass-spectrometric procedure for determining di- and polyamines (putrescine, spermidine, and spermine) in plasma and erythrocytes. Deuterium-labeled analogs of putrescine, spermidine, and spermine were synthesized for use as internal standards. Trifluoroacetyl derivatives of the polyamines were formed during the procedure and then detected with negative-ion chemical ionization/mass spectrometry in combination with multiple ion monitoring. Limits of sensitivity ranged from 0.25 to 1.0 pmol of analyte injected into the instrument.
Enhancement of immune cellular agglutination by use of an avidin-biotin system.
Authors: Costello S M , Felix R T , Giese R W
Published: January 2020

Classically, one can increase the titer of an agglutinating or first antibody with an antiglobulin or second antibody. We have used an avidin-biotin system in place of antiglobulin to similarly extend the agglutination by an initial anticellular antibody. Erythrocytes were agglutinated by adding in succession, caproylamidobiotin-antibody, avidin, and extender (caproylamidobiotin-macromolecule). The macromolecules evaluated as extenders, in order of increasing potency, were fibrinogen, albumin, succinylated polylysine, and ribonuclease A. From comparative testing, we found that antiglobulin raised the titer of antibody from 2560 to 20,480, and the avidin-biotin tool raised the titer of caproylamidobiotin-antibody from 2560 to 10,240 without extender and to 81,820 with an extender of caproylamidobiotin-ribonuclease. Thus noncovalent extenders add to the capability of the avidin-biotin system to facilitate and substitute for an antibody.
A new and universal free/bound separation technique for the "CENTRIA" automated radioimmunoassay system.
Authors: Mériadec B , Jolu J P , Henry R
Published: January 2020

A new separation procedure based on the double-antibody technique has been adapted to the CENTRIA System. This procedure is universally applicable and lends itself to easy adaptation to commercial RIA kits in which liquid reagents are used. This second antibody is covalently linked to agarose (Sepharose) and the lyophilized powder is subsequently tableted for easy use on the instrument. The technique was applied to radioimmunoassay for thyrotropin (thyroid stimulating hormone), alpha-fetoprotein, and ferritin. Performance characteristics were as follows: sensitivity 1.5 milliunits/L, 4.5 micrograms/L, and 4.5 micrograms/L, respectively; intrarun precision 1.7, 9, and 3.4%, and interrun precision 7.6, 13, and 14.5%. All three assays were clinically validated.
Advantages of using thin sodium iodide detectors for thyroid monitoring of personnel working with 125I.
Authors: Landon S , Smith P G , Staniek S P , Webber C E
Published: January 2020

Measurements of neck count-rates for personnel who regularly iodinated proteins with 125I showed that, generally, count rates were higher after iodination than before. The major pathway for the intake of 125I during iodination was through skin that was exposed to the free-iodine atmosphere of the fume hood. Neck count-rates were measured in 34 other subjects who were working with 125I. The rates for 25 of them were significantly greater than for a control group of 36 subjects. Significant activities were also detected in seven of nine subjects who had never worked directly with 125I but who were located within areas where it was used extensively. To minimize thyroid burdens of 125I, it is essential that neck count-rates be measured routinely, in order to monitor the safety of procedures involving the use of 125I.
Mechanism of interference by hemoglobin in the determination of total bilirubin. II. Method of Jendrassik-Grof.
Authors: Shull B C , Lees H , Li P K
Published: January 2020

Oxyhemoglobin in erythrocyte hemolysates interferes with the Jendrassik-Grof assay. Destruction of azobilirubin occurs when oxyhemoglobin is oxidized to methemoglobin during diazotization or to alkaline hematin with addition of alkaline tartrate. The most probable mechanism is by oxidation with an agent such as hydrogen peroxide or a related species resulting from hemoglobin oxidation. Methemoglobin also appears to cause some destruction of azobilirubin during diazotization. Methemoglobin forms during diazotization because of reactions of oxyhemoglobin with both diazo reagent and nitrite ion. Formation of methemoglobin is, therefore, more rapid in the test than in the blank mixture and, under reaction conditions, its absorbance is less than that of oxyhemoglobin. This results in spectral interference when neutral azobilirubin is assayed. Alkaline tartrate abolishes this spectral error by causing rapid formation of alkaline hematin in both test and blank.
Biochemical individuality and the recognition of personal profiles with a computer.
Authors: Robertson E A , Van Steirteghem A C , Byrkit J E , Young D S
Published: January 2020

Multitest analysis of an individual's blood provides a biochemical profile that reflects his identity and pathophysiological state. During a six-week period we repeatedly profiled 10 volunteers for 22 different analytes, using continuous-flow and discrete analyzers (SMAC, KA 150 enzyme analyzer, ABA-100, AutoAnalyzers) and manual procedures. Two years later, we obtained multiple follow-up profiles. Using linear discriminant functions derived from the first five (or first 10) specimens from each subject, we were able correctly to identify 96% (or 100%) of the specimens collected during the remainder of the six-week testing period. Ninety percent of the two-year follow-up specimens were correctly identified when we used all the original profiles to calculate the discriminant functions. Deliberately mislabeled specimens were also correctly identified by discriminant analysis. Profiles of individual samples (and average profiles for each subject) were graphically displayed as computer-drawn faces and non-linear maps. Covariances between pairs of tests on repeated profiles differed significantly for different subjects. Inter-test relationships were graphically displayed by nonlinear mapping.
Screening radioimmunoassay for aldosterone in preheated plasma without extraction and chromatography.
Authors: Connolly T M , Tibor L , Gless K H , Vecsei P
Published: January 2020

We directly estimated plasma aldosterone radioimmunologically with use of an antiserum raised against an aldosterone-3-oxime/bovine serum albumin conjugate, the estimation being on samples with and without heating (60 degrees C), and diluted and undiluted. Values so obtained were compared with those by radioimmunoassay after extraction and chromatography. The correlation--even negative values were obtained--was poorest when the steroid was directly estimated in nonheated, undiluted plasma. Correlations were best (r = 0.918) for preheated and diluted native plasma, and the interassay CV was 9.8% (n = 57). However, there were some extraordinarily high values. After equilibrium dialysis of native and preheated (60 degrees C) plasma (15 plasma samples), the percentages of apparent free aldosterone and cortisol increased from 51.4 +/- 2.6% (SEM) to 64.3 +/- 1.6% and from 11.5 +/- 2.2% to 61.1 +/- 1%, respectively. We conclude that aldosterone-binding proteins play a role in direct radioimmunoassays of aldosterone in plasma, but by heating (with or without diluting) the plasma, direct assay can be used as a simple, fast, and inexpensive screening method.
Circulating CK-MB and CK-BB isoenzymes after prostate resection.
Authors: Kimler S C , Sandhu R S
Published: January 2020

We studied the effect of prostate resection on serum creatine kinase (EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) isoenzymes in 22 patients. Two hours after their operations, two-thirds of these patients had increased total creatine kinase activity. The MB isoenzyme was demonstrated in sera of 66% of the patients and the BB isoenzyme in 76%. MB content varied from 1 to 7% of total creatine kinase activity, the average activity being 7.4 +/- 6 (SD) U/L. BB content varied from 1 to 29% of the total creatine kinase activity, the average activity being 8.5 +/- 5.4 U/L. No patients showed evidence of cardiac damage. In contrast to the enzyme changes associated with cardiac injury, MB isoenzyme seen after prostate resection is usually associated with the appearance of BB activity. In addition, the ratio of lactate dehydrogenase isoenzymes 1 and 2 was "inverted" in only five of the 33 patients, and appeared to corrlate with the degree of hemolysis in the postoperative sera. The prostate contains all three creatine kinase isoenzymes, BB predominating.
Lipid interference in steroid radioimmunoassay.
Authors: Rash J M , Jerkunica I , Sgoutas D S
Published: January 2020

To study lipid interference in steroid radioimmunoassays in which dextran-coated charcoal is used as the separating agent, we tested triolein and phosphatidylcholine as model hydrophobic and amphipathic lipids, respectively. Addition of either caused distortion of the standard curve to an extent that was inversely related to the polarity of the steroid molecule. Both lipids form a dispersion that entraps steroid molecules. When we increased the charcoal concentration, the effect of phosphatidylcholine addition was eliminated for assays of both polar and nonpolar steroids. In contrast, the effect from triacylglycerol was not corrected, particularly in assays of nonpolar steroids. We also studied mixtures of lipids mimicking the mixture of lipids extracted from plasma of normolipemic and hyperlipemic indviduals. The degree of lipemia that can be tolerated differs from assay to assay, and primarily varies directly with the polarity of the steroid being assayed.
Immobilized-enzyme rate-determination method for glucose analysis.
Authors: Sokol L , Garber C , Shults M , Updike S
Published: January 2020

We present a rate-determination method for analyzing glucose. A glucose enzyme electrode serves as the sensor and is made by placing a gel-immobilized layer of glucose oxidase over the tip of a Clark-type O2 electrode. The electrode membrane is made of Teflon and is derivatized by etching with a suspension of colloidal sodium metal in organic solvent. The enzyme is coupled to the membrane surface by use of paraformaldehyde. The immobilized-enzyme method is compared with a similar solution-enzyme method and with the National Glucose Reference method. The immobilized enzyme method compares favorably with the solution-enzyme method and offers the advantages of simplicity, economy of enzyme, and linearity over a greater range of concentration.
A fluorometric determination of sphingomyelinase by use of fluorescent derivatives of sphingomyelin, and its application to diagnosis of Niemann-Pick disease.
Authors: Gatt S , Dinur T , Barenholz Y
Published: January 2020

We synthesized fluorescent derivatives of sphingomyelin (N-acyl-sphingosylphosphocholine) and used them as substrates for several sphingomyelinases. The following five fluorescent probes, each attached to the terminal carbon atom of the fatty acyl residue, were introduced into sphingomyelin: dansyl, pyrene, carbazole, 4-chloro-7-nitrobenz-2-oxa-1,3-diazole, and anthroic acid. We compared the rates at which the fluoro- and radiolabeled sphingomyelins were hydrolyzed. They were the same with the following three spingomyelinases: (a) a purified enzyme from Staphylococcus aureus; (b) at Triton X100-treated extract of human brain (assayed at pH 7.4 in the presence of Mg2+; and (c) aqueous extracts of brain lysosomes, skin fibroblasts, and amniotic cells, assayed at pH 5.0. Homogenates of skin fibroblasts of a patient with Niemann-Pick disease had practically no activity when assayed at pH 5, with fluorosphingomyelin as substrate. When fluorosphingomyelin was mixed in various proportions with natural sphingomyelin, enzymes from each of the three sources hydrolyzed the two substrates at equal rates. The fluorosphingomyelins can be used to estimate with great sensitivity the sphingomyelinase activity in extracts of tissues or cells, in tears, and probably in hair follicles, as well as diagnose Niemann-Pick disease, either pre- or post-natally
Evaluation and clinical application of a dextran-charcoal method for measuring bound testosterone in human plasma.
Authors: Tcholakian R K , Jones G M , Sanborn B M , Rodriguez-Rigau L J , Reimondo G G
Published: January 2020

A method for rapidly determining bound and free testosterone in human plasma is evaluated and described, in which dextran-coated charcoal is used to separate bound and free testosterone. Intra- and inter-assay CV's were 1.9 and 3.8%, respectively. At least 50% of the "bound" testosterone was associated with species that behaved like sex steroid hormone-binding globulin on Sephadex G-25 chromatography and polyacrylamide gel electrophoresis. Bound and free testosterone concentrations were determined in normal men, normal women (during the menstrual cycle and during normal pregnancy), and in women with various degrees of hirsutism. We conclude that determining the circulating proportions of bound and free testosterone is helpful in the diagnostic evaluation of hirsutism in women, and in the investigation of normal and pathological conditions where androgen concentrations may be altered.
Evaluation of a radioenzymic kit for determination of plasma catecholamines.
Authors: Tasseron S J , Fiolet J W , Willebrands A F
Published: January 2020

We evaluated a commercially available reagent test-kit (Upjohn) for simultaneously determining norepinephrine, epinephrine, and dopamine in 50-microL of plasma. The three catecholamines are enzymically converted into the radioactive O-methyl derivatives and separated by thin-layer chromatography. Day-to-day precision (CV) was 11, 10, and 14% for norepinephrine, epinephrine, and dopamine, respectively. The relationship between concentration of catecholamine and radioactivity (net dpm) was linear to at least 8 ng (corresponding to 1 mumol/L in plasma). Sensitivity was approximately 2 pg for dopamine, 1 pg for each of the other two catecholamines. Under our conditions, epinephrine was not quite completely resolved from the other two fractions. Catecholamine values determined in normal humans, after 30 min supine and after normal laboratory activity, agreed well with those found by other investigators. Correlation was good between kit results and those obtained in another laboratory that used self-prepared reagents and "high-performance" liquid chromatography for the separation.
Determination of urinary placental estriol by reversed-phase liquid chromatography with fluorescence detection.
Authors: Taylor J T , Knotts J G , Schmidt G J
Published: January 2020

We describe a liquid-chromatographic procedure for determining urinary estriol concentrations. The urine sample, after enzymatic hydrolysis to free the conjugated estrogen, is extracted with ether, and an aliquot of the resulting extraction residue is injected into the liquid chromatograph. Sample components are separated with a reversed-phase C18 column and isocratic elution with an acetonitrile/water mobile phase. Using a far-ultraviolet excitation wavelength, we measure the natural fluorescence of the eluted estrogen with a fluorescence detector. The procedure provides excellent sensitivity for determing near-term pregnancy concentrations of urinary estriol. The selectivity of the method limits the effect of potentially interfering compounds.
The multilayered film analyzer: glucose in serum, plasma, cerebrospinal fluid, and urine; and urea nitrogen in serum and plasma.
Authors: Warren K , Kubasik N P , Brody B B , Sine H E , D'Souza J P
Published: January 2020

Some basic laboratory performance criteria were studied for the Eastman Kodak glucose and urea nitrogen analyzer. Serum, plasma, urine, and cerebrospinal fluid were tested. Precision, both "within-day" and "between-day," for both analytes was less than 2.2% (CV). Both analytes demonstrated linearity, with about 100% recovery of added substrates. Comparisons with continuous-flow procedures demonstrated good correlation. A variety of sera and plasmas can be used for glucose analysis; oxalate--fluoride-treated plasma is unacceptable for use in analysis for urea nitrogen. We saw no effects on glucose or urea nitrogen analysis from hemolysis, lipemia, icterus, some common drugs, ammonia, or abnormally high protein concentrations. Minimum amounts detectable were: glucose (serum) 104 mg/L; glucose (cerebrospinal fluid) 100 mg/L; and urea nitrogen (serum) 21 mg/L. Calibration procedures are discussed for protein-based and aqueous samples.
Parallel evaluation of Astra 8 and Astra 4 multichannel analyzers in two hospital laboratories.
Authors: Truchaud A , Hersant J , Glikmanas G , Fievet P , Dubois O
Published: January 2020

We evaluated the new Beckman multichannel analyzers Astra 8 and Astra 4. Both instruments performed the following tests: Na, K, Cl, CO2, urea, glucose, and creatinine in plasma and Na, K, Cl, and creatinine determinations in urine. We tested precision, accuracy, and linearity at the usual concentrations in plasma and urine. We compared the Astra 8 and Astra 4 with continuous-flow (SMA 6) and discrete analyzers such as IL 243, Beckman KLiNa Flame, Beckman System 1, Corning 920 M Chloride Meter, and the Corning Blood-Gas Analyzer 175. Special tests were performed on plasma-to-plasma and urine-to-plasma carryover. Both analyzers are easy to operate and suitable for both emergency and routine use.
Measurement of sodium valproate in serum by direct-insertion chemical-ionization/mass spectrometry.
Authors: Schier G M , Gan I E , Halpern B , Korth J
Published: January 2020

To quantitatively determine sodium valproate, we use a stable isotope-labeled internal standard and chemical-ionization/mass spectrometry, without prior chromatographic separation. The technique is rapid, simple, sensitive, and provides for the routine analysis of 100 microL of serum with good within-day and day-to-day precision. The technique also allows for the simultaneous determination of phenobarbital, mephobarbital, carbamazepine, primidone, and phenytoin.
Clinical evaluation of an immunoinhibition procedure for creatine kinase-MB.
Authors: Obzansky D , Lott J A
Published: January 2020

We have clinically evaluated the Dade "Cardiozyme" immunoinhibition procedure for determination of creatine kinase isoenzyme MB (CK-MG) in 71 patients who were suspected of having had an acute myocardial infarction. Electrophoresis for CK-MB was also carried out. On the basis of diagnostic sensitivity and specificity for myocardial infarction, we found the Dade procedure for CK-MB to be somewhat inferior to electrophoresis. In 11 patients for whom the time of infarction was known, we observed normal CK-MB results for two of them by both immunoinhibition and electrophoresis during the first 24 h, but subsequently could detect abnormal CK-MB results by both methods. Thus in some patients such data are not helpful for making a diagnosis in the first 24 h. The Dade procedure is easy to perform, but lacks sensitivity in the region of low CK-MB activity, requires a very stable spectrophotometer, is imprecise, and produces negative numerical results in patients without myocardial infarction.
Improved radiochemical method for measuring ferrochelatase activity.
Authors: Williams H L , Johnson D J , Haut M J , Slater S , Brennan R G , Altstatt L B
Published: January 2020

We describe a radiochemical method for measuring ferrochelatase activity in the in vitro incorporation of iron into mesoporphyrin-IX to form mesoheme. 59Fe is used to quantify ferrochelatase activity in rat liver. The uptake of iron is linearly related to the time allowed for it to occur, and the reaction proceeds optimally under reducing and anerobic conditions, maintained in sealed lyophilization vials under a positive pressure of nitrogen.
Use of an alumina column in estimating total iron-binding capacity.
Authors: Starr R T
Published: January 2020

I describe a simple, rapid technique for saturating the transferrin in serum and then removing unbound (excess) iron. This technique involves use of an easily prepared column of basic chromatographic alumina and a saturating solution of ferric chloride in citric acid. This method, when compared with the magnesium carbonate method of Ramsay (Clin. Chim. Acta 2: 221, 1957) by regression analysis and tests of precision, showed a negative bias for results by the alumina technique with respect to the magnesium carbonate method.
An improved ultrafiltration method for free thyroxine and triiodothyronine in serum.
Authors: Sophianopoulos J , Jerkunica I , Lee C N , Sgoutas D
Published: January 2020

We describe an ultrafiltration technique for rapidly and directly determining free triiodothyronine or free thyroxine, or both. After equilibrating serum at 37 degrees C with purified tracer of high specific activity, we placed 0.15 mL of serum in 2.8 mL of phosphate buffer (0.1 mol/L, pH 7.4) in the ultrafiltration cell and obtained successive 0.2- and 0.6-mL fractions of protein-free ultrafiltrate. Under our conditions free ligand concentration was independent of flow rate. After purifying the second fraction with protein-coated charcoal, we could determine the proportion of free triiodothyronine or free thyroxine. Samples from normal adult men and women, including women who were taking oral contraceptives or were pregnant, and from hypo- and hyperthyroid patients gave results that agreed with those obtained by equilibrium dialysis. Speed is the main advantage of the method: one technologist can complete the procedure in 2 h and, using a multi-micro-ultrafiltration system, can process many samples in one day. For laboratories where index-type reactions are performed routinely and direct free triiodothyronine or free thyroxine is determined only on selected specimens, this method is superior to dialysis. It is also very convenient for rapidly purifying tracers, to at least 97% radiochemical purity, with 94% recovery and no dilution.
Comparison of turbidimetric and light-scattering measurements of immunoglobulins by use of a centrifugal analyzer with absorbance and fluorescence/light-scattering optics.
Authors: Hills L P , Tiffany T O
Published: January 2020

We have developed a centrifugal analyzer with both fluorescence/light-scatter and conventional absorbance optics. The instrument is used in this investigation to study the formation of antigen-antibody complexes by light scattering and turbidimetric measurements, and to develop assays for human immunoglobulins G, A, and M. Concentrations are calculated from a nonlinear least-squares fit of calibrators, and antigen excess is automatically detected from kinetic curve characteristics. Precisions and patients’ results are presented, and assay sensitivity and reliability in the detection of antigen excess are compared. We also investigated the effects of centrifugal force on complex formation. Both nephelometry and turbidimetry can be very satisfactorily adapted to centrifugal analyzers. We present a model to describe the observed differences between the light-scatter and the turbidity data.
Determination of organic acids in biological fluids by ion chromatography: plasma lactate and pyruvate and urinary vanillylmandelic acid.
Authors: Rich W , Johnson E , Lois L , Kabra P , Stafford B , Marton L
Published: January 2020

We describe the general aspects of ion chromatography and how on-line counted ion-exchange techniques can be utilized to determine pyruvic and lactic acids in plasma and vanillymandelic acid in urine. Pyruvate and lactate are extracted from deproteinized plasma by use of an ion-exclusion resin. After elution from the resin, the plasma extract is chromatographed on an anion-exchange column, with 0.66 mmol/L sodium bicarbonate as the mobile phase. The effluent is detected with an electrical conductivity cell. Vanillylmandelic acid is extracted from diluted urine by use of an anion-exchange resin. After elution from resin, the urine extract is chromatographed on an ion-exclusion column, followed by electrochemical detection. We evaluated the procedures for precision, linearity, analytical recovery, intefering substances, and correlation with an established procedure. the combination of a preliminary resin extraction, an ion chromatographic separation, and a conductivity or electrochemical detector results in rapid, specific methods that can be adapted for use in the clinical laboratory. Preliminary data for other organic acids are presented.
Serum protein profiles by "high-performance" liquid chromatography with detection at multiple wavelengths.
Authors: Schlabach T D , Abbott S R
Published: January 2020

We have separated serum proteins in only 15 min by high-performance liquid chromatography. The identification of several peaks in the chromatographic profile was greatly aided by the use of multiple-wavelength detection. We have found a good correlation between retention times and electrophoretic mobilities. Serum samples with increased γ- or β-globulins, as determined by electrophoresis, resulted in chromatographic profiles with strongly increased peaks in the appropriate regions. This chromatographic method revealed both relative and absolute differences in individual protein concentrations among several serum samples.
Concentration of immunoreactive trypsin and activity of pancreatic isoamylase in serum compared in pancreatic diseases.
Authors: Fahrenkrug J , Magid E
Published: January 2020

We measured the concentration of immunoreactive trypsin and the enzymic activity of pancreatic isoamylase in sera from 103 patients with pancreatic diseases and 29 other subjects serving as a reference group. Almost all patients with pancreatic diseases had abnormal values for both enzymes. A strong positive correlation between these two variables over a 1000-fold range was observed.
Rapid, fully automated radioimmunoassay of prostatic acid phosphatase in serum.
Authors: Dass S , Bowen N L , Bagshawe K D
Published: January 2020

Prostatic acid phosphatase was purified from human semen and its purity established by biochemical and immunological criteria. Rabbits were injected with the purified isoenzyme to raise specific antisera. The prostatic acid phosphatase was radiolabeled with 125I by the Chloramine T method. We developed a fully automated double-antibody radiommunosassay for measuring prostatic acid phosphatase in serum from patients with carcinoma of the prostate and from several control groups. The lower detection limit of the radioimmunoassay was 2.0 microgram of prostatic acid phosphatase per litre of serum. Values for most members of the control group was <2.0 microgram/L; patients with metastatic carcinoma of the prostate had values ranging from <2.0 to 300 microgram/L of serum.
"ULtra-clean" isotope diultion/mass spectrometic analyses for lead in human blood plasma indicated that most reported values are artificially high.
Authors: Everson J , Patterson C C
Published: January 2020

We measured lead concentrations in venous blood plasma from two subjects, one having a typical exposure and the other a high exposure to lead. Our preliminary data, obtained by isotope dilution/mass spectrometric techniques in an ultra-clean laboratory, show lead concentrations of 0.02 mug/L and 2 mug/L, respectively, in their blood plasma, and 110 mug/L and 800 mug/L, respectively, in samples of whole blood. These results indicate that plasma lead concentrations previously reported have been overestimated by a large factor, and that further improvements in analytical procedures are needed in most laboratories before data on lead concentratios in blood plasma can be properly interpreted. Our preliminary data indicate a positive correlation between lead intake and lead concentrations in blood plasma.
Detection of alkaline phosphatase/immunoglobulin complexes.
Authors: Buttery J E , Milner C R , Nenadovic P , Pannall P R
Published: January 2020

We report another patient with a circulating alkaline phosphatase/immunoglobulin complex in his blood, and describe a simple method of demonstrating such complexes. On electrophoresis on cellulose acetate, the complex was relatively slow moving and there was no activity in the normal bone/liver isoenzyme region. When the serum was treated with trypsin, the slow band disappeared and the normal pattern was restored.
Single- and coupled-enzyme nylon-tube reactors for plasma glucose determination with glucose oxidase and aldehyde dehydrogenase.
Authors: Hinsch W , Antonijewić A , Sundaram P V
Published: January 2020

We describe routine methods for determining glucose in plasma with use of aldehyde dehydrogenase or glucose oxidase-aldehyde dehydrogenase immobilized in a nylon tube that is integrated into a continuous-flow system. Although the coupled-enzyme nylon-tube reactors require the presence of a third enzyme, catalase, in solution, the kinetics are not so complicated as to preclude reliable routine determination of glucose at very low cost. Precision is good, and results correlate well with those by the method involving glucose oxidase in solution. More than 3000 tests may be carried out with one reactor. The immobilized enzymes are stable for several months at 4 degrees C when not in use.
Reactivity of amniotic fluid alpha-fetoprotein with concanavalin A in relation to gestational age: clinical implications.
Authors: Toftager-Larsen K , Kjaersgaard E , Jacobsen J C , Nørgaard-Pedersen B
Published: January 2020

We used concanavalin A crossed-line affinity immunoelectrophoresis to determine the percentage of concanavalin A nonreactive alpha-fetoprotein in amniotic fluid samples from pregnancies with normal and abnormal fetuses. In 167 samples from pregnancies with a normal outcome and normal values for total alpha-fetoprotein concentration in amniotic fluid the percentage decreased from a median value of 27.4% in the 13th week to 8.5% in the 21st week of gestation, and a statistically significant (p < 0.001) average decrease of 1.7% per week was found from the 14th to the 19th week. A similar average decrease (2.2%) was found in 22 pregnancies from which two or more samples were obtained. The clinical significance of this decrease is discussed. Of 108 samples from patients with above-normal values for total alpha-fetoprotein and a normal outcome, seven had a total alpha-fetoprotein above recommended cut-off values, and only one of these had a low percentage of concanavalin A nonreactive alpha-fetoprotein. In contrast, for all 27 samples from pregnancies with a severe fetal malformation this percentage was low, even in one case where the total alpha-fetoprotein concentration was below the recommended cut-off value.
C-terminal parathyrin (parathyroid hormone) radioimmunoassay in serum with commercially available reagents.
Authors: Simon M , Cuan J
Published: January 2020

We describe a sequential double-antibody assay for measuring C-terminal parathyrin in serum with commercially available reagents. Intact bovine hormone, used as a working standard, is iodinated by conventional Chloramine T procedures. The antibody affinity is characteristic of high affinity binding (1.4 to 1.6 x 10(10) L/mol of intact parathyrin). The antibody also cross reacts with a C-terminal parathyrin fragment (amino acids 53-84) but not with a synthetic N-terminal parathyrin fragment (amino acids 1-34). The assay thus also measures both a C-terminal fragment of parathyrin and the intact hormone. The detection limit (250 ng/L; 500 int. units/L) is below the reference interval for healthy adults (430-1860 ng/L; 860-3720 int. units/L). Several commonly recognized problems with iodinated parathyrin are eliminated and accuracy and precision of the procedures for standard preparation and calibration are improved. Overall CV (between-run imprecision) is 10-17%. Analytical recovery is 80-90%, and C-terminal parathyrin measured in fresh sera and in sera stored for seven days at 30 degrees C is equivalent.
Magnetizable solid-phase fluoroimmunoassay of thyroxine by a sequential addition technique.
Authors: Nargessi R D , Ackland J , Hassan M , Forrest G C , Smith D S , Landon J
Published: January 2020

We describe a simple fluoroimmunoassay for the determination of thyroxine concentrations in serum. The method, "sequential addition, separation fluoroimmunoassay," involves both thyroxine labeled with fluorescein and magnetizable cellulose/iron oxide particles to which antibodies to thyroxine have been covalently linked. Serum sample or standard is incubated with an excess of the solid-phase antibody; the particles, which now carry most of the antigen in the sample, are sedimented onto a magnet and the supernate, which contains endogenous fluorophores and other interfering factors, is removed and discarded. Excess labeled thyroxine is then added, and, after incubation, the fluorescence in the supernate (free fraction), which is related directly to the amount of thyroxine in the sample is measured. For the whole procedure, including fluorometry, each sample is treated entirely within disposable polystyrene test tubes. Correlation studies with two different radioimmunoassays showed good agreement.
Study of an enzyme immunoassay kit for carcinoembryonic antigen.
Authors: Maiolini R , Bagrel A , Chavance C , Krebs B , Herbeth B , Masseyeff R
Published: January 2020

We evaluated a commercial enzyme immunoassay kit for carcinoembryonic antigen (CEA) based on a non-competitive "sandwich principle" method (Abbott Laboratories). The serum sample is treated with an acid buffer and the supernate is incubated with an anti-CEA coated polystyrene bead. After washing, the bead is incubated with an anti-CEA/peroxidase conjugate. After a second washing, the activity of the enzyme bound to the solid phase is assayed after addition of a chromogenic substrate. This activity is proportional to the concentration of CEA in the serum sample. The characteristics of the assay are: (a) good sensitivity (around 0.25 microgram/L) and (b) satisfactory reproducibility (CV < 11% within assay). There is little cross reactivity between CEA and molecules such as nonspecific cross-reacting antigens that are known for their high potential of cross reactivity. No nonspecific interference was encountered with anti-globulin factors. We compared results with this enzyme immunoassay kit with those by a radioimmunoassay provided by the Commissariat à l'Energie Atomique. The correlation (r) was 0.95 (p < 0.001). The distribution of CEA values obtained for 1020 normal subjects is given. We conclude that the kit provides a simple and reliable procedure.
Evaluation of a new homogeneous enzyme inhibitor immunoassay of serum thyroxine with use of a bichromatic analyzer.
Authors: Finley P R , Williams R J , Lichti D A
Published: January 2020

We evaluated a new homogeneous enzyme immunoassay of thyroxine with use of a discrete analyzer (the ABA-100 Bichromatic Analyzer), modified with an auxiliary dispenser assembly. The assay is based on inhibition of hydrolysis of the substrate, acetyl-beta-(methylthio)choline iodide, by acetylcholinesterase (acetylcholine hydrolase; EC 3.1.1.7). Thyroxine covalently linked to a cholinesterase inhibitor irreversibly inhibits acetylcholinesterase, but if this thyroxine conjugate is bound to antibody it is not inhibitory. Seventy-five patients' samples may be analyzed in 1 h of instrument time. Precision and accuracy are excellent, results correlate well with those by radioimmunoassay, and there were no instances of confused clinical interpretation resulting from use of the proposed assay.
Specific serum pancreatic lipase determination, with use of purified colipase.
Authors: Hoffmann G E , Weiss L
Published: January 2020

We show that the turbidimetric method of Ziegenhorn et al. (Clin. Chem. 25: 1067, 1979) for determination of pancreatic lipase is not influenced by lipoprotein lipase. This improved specificity as compared to standard lipase methods is explained by the presence of purified colipase and the high concentration of bile acids in the substrate emulsion.
Bence Jones myeloma with a tetramer of kappa-type globulin in serum.
Authors: Gallango M L , Suinaga R , Ramírez M
Published: January 2020

We describe a case of Bence Jones multiple myeloma involving two kappa-type monoclonal proteins. One was isolated from serum, the other from both serum and urine. After biochemical and immunochemical analyses, we concluded that one of the proteins was a tetramer, present in serum but not in urine, whereas the other was a monomer, which was excreted in large amounts in the urine during the terminal stage of the disease.
Evaluation of baboon antiserum to carcinoembryonic antigen.
Authors: Haagensen D E , Cox C E , Dilley W G , Hensley M , Murdoch J , Newman E S , Wells S A
Published: January 2020

The common baboon (Papio), immunized with carcinoembryonic antigen (CEA), was found to form specific-site antibodies for CEA. The baboon antiserum does not recognize colon carcinoma antigen-III, but does demonstrate similar ionic strength effects to those previously described for goat antisera to the CEA-specific site(s). Baboon specific-site antibody for CEA can be used for radioimmunoassay of CEA in plasma and gives similar results to the commercial (Roche) goat anti-CEA.
Enzyme immunoassay of estriol in pregnancy urine.
Authors: Korhonen M K , Juntunen K O , Stenman U H
Published: January 2020

We describe an enzyme immunoassay for determination of total estriol in urine. Estriol covalently bound to horseradish peroxidase is used as tracer, and free and bound hormone are separated by precipitation with polyethylene glycol. The method can be used with either acid hydrolysis at 100 °C for 30 min or enzyme hydrolysis at 50 °C for 40 min; results by the former procedure are about 15% lower than results by the latter. Results were practically identical when we compared the enzyme immunoassay with a radioimmunoassay, using the same antiserum and method of hydrolysis. The day-to-day CV for three different concentrations was 10.7-12.0%, the within-series CV 6.6-8.6%. The additional time required for the enzyme reaction is compensated for by the rapid measurement of light absorbance. Thus this method is faster than radioimmunoassay when more than 25 samples are to be assayed.
New method for liquid-chromatographic measurement of erythrocyte protoporphyrin and coproporphyrin.
Authors: Salmi M , Tenhunen R
Published: January 2020

We describe a “high-pressure” liquid-chromatographic method for separating all the porphyrins in the heme biosynthetic pathway. The preliminary extraction and purification method is such that only erythrocyte porphyrins with fewer than five carboxyl groups, which includes protoporphyrin and the much smaller amount of coproporphyrin present, are measured. The porphyrins extracted from erythrocytes are chromatographically separated by use of a simple eluent system and fluorometrically detected.
Double-antibody immunoenzyme assay for human prostatic acid phosphatase.
Authors: Choe B K , Pontes E J , Dong M K , Rose N R
Published: January 2020

We compare the double-antibody radioimmunoassay (RIA) and immunoenzyme assay (IEA) for measuring the concentration of prostatic acid phosphatase in human serum. Experimental details and assay performance of the two methods are outlined. Mean values for 385 normal persons were 1.02 (SD 1.32) microgram/L by IEA, 2.69 (SD 1.8) microgram/L by RIA. Results of the two methods was highly correlated [r = 0.9813, y(RIA) = 0.35 x (IEA) + 0.42, p < 0.001]. If we choose x- + 2 SD as the normal range, 3-10% false positives were seen.
Changes in transcutaneous oxygen tension during capillary blood-gas sampling.
Authors: Graham G , Kenny M A
Published: January 2020

With a Radiometer TCM-1 oxygen monitor, we followed the fluctuations in transcutaneous oxygen tension (ptcO2) during capillary blood collection from a heel prick. Thirty premature infants who presented with some respiratory compromise showed unpredictably increased (43 of 125 observations) or decreased (82 of 125 observations) values during this blood-sampling process. The fluctuation exceeded 10 mmHg in 61 observations and represented as much as -67% relative change. In general, ptcO2 values exceeded capillary pO2 values determined by standard blood-gas analysis. We investigated several aspects of capillary blood sampling to explain these observations. Because the induced response is a dynamic change, which continues throughout the collection process, we conclude that successive specimens will have different O2 tensions. Even if the capillary blood pO2 truly reflected paO2, the magnitude and direction of deviation from the patient's uncompromised O2 tension could lead to inappropriate management. We conclude that capillary blood specimens should not be used for pO2 determinations in newborns.
Analysis of fluorescence quenching data by the method of Levine.
Authors: Parsons D L
Published: January 2020

The quenching of intrinsic protein fluorescence upon binding of ligand is a relatively quick and easy method for studying these interactions. The method of Steiner et al. (J. Biol. Chem. 241: 560, 1966) and the method of Levine (Clin. Chem. 23: 2292, 1977) have been used by different authors to interpret the data obtained from fluorescence-quenching studies. However, as is shown here, the method of Levine is not strictly valid when the protein contains more than one binding site for the ligand. Therefore, this method only approximates binding constants from such data, with an accuracy that depends on the specific binding properties of the interactants.
Novel reagent and method for direct determination of chloride in serum with a centrifugal analyzer.
Authors: Law W T , Ertingshausen G
Published: January 2020

We report a novel reagent containing ferric perchlorate, perchloric acid, and polyoxyethylene (23) lauryl ether (Brij 35) with which the concentration of chloride in serum can be measured. We applied this reagent to use with a centrifugal analyzer (CentrifiChem 400) in a dynamic bichromatic procedure, resulting in broad linearity of the standard curve (0-180 mmol/L), short analysis time (1 min), and little interference from bilirubin, hemoglobin, turbidity, or bromide ions. The reagent is simple, contains no mercury, and the combination of low acid concentration and surfactant prevents serum protein precipitation. Precision is good (for x- = 93 mmol/L, CV = 1.55%), and results correlate well with those obtained by coulometry (r = 0.974).
Conductometric titration of hydrochloric acid in gastric juice.
Authors: van Zanten A P , van den Ende A
Published: January 2020

We describe a procedure for the determination of hydrochloric acid concentration in gastric juice by means of a conductometric titration of the 50-fold diluted sample with an aqueous ammonia solution. The conductometric method of endpoint indication leads to a definite location of the equivalence point in the titration of hydrochloric acid. The proposed method is simple and accurate and shows a good correlation with an accepted method for the measurement of gastric acidity.
Evaluation of an enzyme immunoassay for determining diazepam and nordiazepam in serum and urine.
Authors: Wallace J E , Harris S C , Shimek E L
Published: January 2020

We evaluated a commercially available enzyme immunoassay method for determining the concentration of total diazepam plus its active metabolite, nordiazepam, in small amounts of serum and urine. The coefficients of variation were 5% within assay and 8% between assay. Concentrations so measured for patients’ sera correlated well with those obtained both by gas chromatography with electron-capture detection and by liquid chromatography with ultraviolet detection. For urine samples, the correlation between values obtained by the enzyme immunoassay method and those for total diazepam/nordiazepam/oxazepam obtained by liquid chromatography was adequate for routine clinical toxicological use. The ability of the immunoassay to determine other benzodiazepines was also evaluated.