bluuebunny/crossref_metadata_2025 huggingface dataset:
Reference interval for prealbumin for children two to 36 months old.
Authors: Sherry B , Jack R M , Weber A , Smith A L
Published: January 2020

To define a reference value for serum prealbumin (transthyretin) concentration, we used a rate immunonephelometric microassay to quantify it in 76 healthy children, ranging in age from two to 36 months. Age-specific ranges (+/- 2 SD from the mean) are: 2-5.9 months, 142-330 mg/L; 6-11.9 months, 120-274 mg/L; 12-17.9 months, 115-259 mg/L; 18-23.9 months, 143-243 mg/L; 24-36 months, 108-258 mg/L. When the data were grouped into those for subjects younger and older than 12 months of age, the mean for the 2-11.9 month age group (210 mg/L) significantly (P less than 0.01) exceeded that of the 12-36 month age group (187 mg/L). We propose that in spite of a decrease in prealbumin concentration with increasing age, it is acceptable to use the reference interval 116-281 mg/L (+/- 2 SD from the mean) for children from two to 36 months old. We also compared concentrations of prealbumin in serum and plasma of 41 individuals, finding the mean difference to be +11.7 mg/L; concentrations in plasma averaged 6.7% greater than those in serum.
Patterns of lactate dehydrogenase isoenzymes in serum of patients with acute pulmonary edema.
Authors: Rotenberg Z , Weinberger I , Davidson E , Fuchs J , Sperling O , Agmon J
Published: January 2020

Total lactate dehydrogenase (LD; EC 1.1.1.27) activity in serum and proportions of LD isoenzymes were quantified on admission and discharge in 170 selected (from 240) patients with acute pulmonary edema (APE). The patients were divided into group A, 75 patients with normal LD values (less than 225 U/L); and groups B-E, with increased LD activity in serum: group B, 40 patients with increase in the proportion of LD-3 (greater than 38%); group C, 12 patients with increased LD-5; group D, 36 patients with an isomorphic pattern of LD isoenzymes; and group E, seven patients with LD-1/LD-2 greater than 0.75. Nine patients in group C (75%) had also signs of right-sided congestive heart failure, 30 in group D (83%) had hypotension on admission, and six in group E (86%) had signs of recent myocardial infarction. Evidently, half of patients with APE may show increased total LD activity in serum at the time of admission. LD isoenzyme proportions should be determined in such patients, because there is no one typical pattern of LD isoenzymes and some LD isoenzyme patterns may be associated with specific clinical situations.
Simultaneous liquid-chromatographic determination of prednisone and prednisolone in plasma.
Authors: Cheng M H , Huang W Y , Lipsey A I
Published: January 2020

This high-performance liquid-chromatographic (HPLC) method for simultaneous determination of prednisone and its metabolite, prednisolone, in plasma is a modification of the method of Frey et al. (Clin Chem 1979;25:1944-7). Heparinized plasma (1.0 mL) with 0.1 mL of internal standard solution (11-deoxy-17-hydroxycorticosterone, 2 mg/L) is extracted with 7.0 mL of dichloromethane, then washed sequentially with 0.1 mol/L HCl, 0.1 mol/L NaOH, and deionized water, 2.0 mL each. The extract is evaporated and the residue reconstituted with 75 microL of mobile phase, methanol/H2O (40/60 by vol). Thirty microliters of this is injected onto a reversed-phase C6 column, which is eluted at 1.4 mL/min. Analytical recoveries of prednisone and prednisolone were 94-98% and 102-106%, respectively. Day-to-day precision (CV) was 3.8% for prednisone, 6.1% for prednisolone. We encountered no interference from the 21 other steroids and 25 drugs tested. This method is simple, accurate, and precise.
Improved determination of vanadium in biological fluids by electrothermal atomic absorption spectrometry.
Authors: Ishida O , Kihira K , Tsukamoto Y , Marumo F
Published: January 2020

We made sensitive and accurate electrothermal atomic absorption spectrometric measurements of vanadium in small volumes of serum. The wet-digested sample was extracted into an organic solvent, with N-benzoyl-N-(o-tolyl)hydroxylamine (BTA) as the chelating reagent. After evaporating the solvent, we dissolved the residue in acetic acid, and injected a 60-microL aliquot into a graphite furnace. In this way we could measure vanadium concentrations as low as 80 ng/L in 4 mL of serum. The within-run CV was 3.3% for serum, 7.7% for urine. Analytical recoveries of vanadium added to serum and urine were 90.3% and 90.8%, respectively. We measured vanadium concentrations in sera from 64 healthy persons (group 1), 15 nondialyzed uremic patients (group 2), and 11 hemodialyzed patients (group 3). The highest concentration of vanadium in group 1 was 240 ng/L; about 60% of the values for this group were less than 80 ng/L. In group 3, the vanadium concentrations were extremely high (15 +/- 14.2 micrograms/L, mean +/- SD), less so (but still above normal) in group 2 (1.58 +/- 3.16 micrograms/L).
Four fluorescence polarization immunoassays for therapeutic drug monitoring evaluated.
Authors: Haver V M , Audino N , Burris S , Nelson M
Published: January 2020

We evaluated four fluorescence polarization immunoassays--those for phenytoin, procainamide, N-acetylprocainamide (NAPA), and quinidine--from Roche Diagnostic Systems, done in the Cobas Bio FP centrifugal analyzer. The assays for phenytoin, NAPA, and quinidine demonstrated a linear response over the expected ranges of concentrations, and analytical recovery of test drug added to drug-free sera was greater than 90%. However, recovery in the procainamide assay was poor (69-82%) for samples containing greater than 8 mg/L, owing to nonlinearity. Results of method-comparison studies of the four assays paralleled the recovery studies, although the quinidine assay demonstrated a bias (1.0 mg/L higher) when compared with EMIT (Syva). The precision of the phenytoin assay was acceptable at all concentrations tested (total CV less than 7.0%). Imprecision of the other assays was significant at certain concentrations: total CV greater than 10.0% at subtherapeutic values for NAPA and quinidine, and greater than 9.0% for low (2.4 mg/L) and moderate concentrations (9.6 mg/L) of procainamide. Interferences were not significant for hemolyzed, icteric, or lipemic specimens or for specimens with added drug metabolites. The calibration curves for all four assays had good stability (greater than 60 days).
Effect of ether or ketamine anesthesia on rat uterine estrogen and progesterone receptors.
Authors: Zarembka F R , Koller D E , Plotka E D
Published: January 2020

Rat uterine estrogen receptors (ER) and progesterone receptors (PR) have been used as controls in ER and PR assays of breast tumors. Stunning or decapitation of experimental animals without prior anesthesia is no longer acceptable as a method of killing. Thus, we compared the effects of two anesthetics on the concentration of rat uterine ER and PR. Rats were killed by one of three methods: (a) stunning, (b) ether anesthesia followed by decapitation, or (c) ketamine anesthesia followed by decapitation. ER and PR concentrations were determined by titration assay, with dextran-coated charcoal separation, and quantified by Scatchard analysis. No significant differences were found in mean receptor concentrations or dissociation constants for the three groups. The results indicate that there is no residual effect of diethyl ether or ketamine hydrochloride on the binding of either estrogen or progestin to their respective receptors. The use of decapitation after either ether or ketamine anesthesia is appropriate for measuring ER and PR receptors in rat uteri.
Solving the problem of antibody interference in commercial "sandwich"-type immunoassays of carcinoembryonic antigen.
Authors: Hansen H J , LaFontaine G , Newman E S , Schwartz M K , Malkin A , Mojzisik K , Martin E W , Goldenberg D M
Published: January 2020

We evaluated the effect of human anti-murine antibodies (HAMA) on apparent concentrations of carcinoembryonic antigen (CEA) as measured in serum with commercial enzyme immunoassay (EIA) kits manufactured by Abbot ("two-step" double monoclonal antibody assay), Roche, and Hybritech (room-temperature protocol). In sera from patients given parenteral murine monoclonal antibody for experimental diagnostic and immunotherapy studies, HAMA titers were determined with Immunomedics' "ImmuSTRIP HAMA-EIA" kit reagents. "True" CEA titers were established by using the ImmuCEA/MA-EIA and heat-extraction to destroy HAMA before assay for CEA. The concordance of the ImmuCEA/MA assay with the Abbott and Roche CEA EIAs was established with sera from normal individuals and from patients who had not received parenteral injections of murine monoclonal antibody. At high (100 mg/L) concentrations of HAMA, false-positive results were observed with all three kits. The Hybritech and Roche assays were more sensitive to interference by HAMA than was the Abbott CEA-EIA, false-positive results being observed at HAMA concentrations between 1 and 10 mg/L. Similar sensitivity of the three kits to interference by primate anti-MAb sera was demonstrated. Use of primate anti-MAb sera to create controls with HAMA activity and of analyte is recommended to evaluate MAb assays for potential HAMA interference and for use to devise methods to eliminate HAMA interference.
Concentration of free thyroxin in serum during nonthyroidal illness--calculation or measurement?
Authors: Konno N , Hirokawa J , Tsuji M , Hagiwara K , Taguchi H , Murakami S , Taguchi S
Published: January 2020

We measured the free thyroxin (FT4) concentration in serum from 79 patients with nonthyroidal illnesses (NTI), using two analog RIAs and two calculation methods, and compared the results with those by ultrafiltration (UF) as a reference. The percentage of NTI patients with subnormal concentrations of FT4 was 10.1% by UF; 20.3% by mathematical calculation (MC) according to mass-action theory; 19.0% by FT4 index (FT4I), calculated by the triiodothyronine-albumin uptake method expressed as the bound:free ratio; 37.2% by Amerlex M FT4 (P less than 0.001 vs UF, P less than 0.025 vs MC); and 33.3% by Coat-A-Count FT4 with albumin blocker (P less than 0.001 vs UF, P less than 0.025 vs MC). No significant correlations were found between FT4 (UF) and T4-binding proteins (TBP) in serum, but FT4 (MC) correlated with T4-binding globulin (TBG) (r = 0.383, P less than 0.001), FT4I with TBG (r = 0.345, P less than 0.001), FT4 (Amerlex M) with albumin (r = 0.491, P less than 0.001), and FT4 (Coat-A-Count) with TBG (r = 0.636, P less than 0.001). All FT4 measurements correlated well with each other, but correlations were stronger between both calculated FT4 values and FT4 (UF), r = 0.702 to 0.760, than between both values for RIA and FT4 (UF), r = 0.475 to 0.665. These results indicate that in comparison with the UF method, both calculated FT4 values are little affected by TBP concentrations, and FT4 (MC) or FT4I by T3-albumin uptake may be more appropriate than analog RIA for evaluation of circulating FT4 concentration in NTI.
Adenosine and dopamine simultaneously determined in urine by reversed-phase HPLC, with on-line measurement of ultraviolet absorbance and electrochemical detection.
Authors: Echizen H , Itoh R , Ishizaki T
Published: January 2020

This assay method allows the simultaneous determination of adenosine and dopamine in 0.5 mL of human urine within approximately 35 min, by using isocratic, reversed-phase, high-performance liquid chromatography coupled with an on-line detector for ultraviolet absorbance and electrochemical activity. The analytes were rapidly separated on an affinity column packed with phenylboronate-bonded silica. Mean recoveries for adenosine, 2-chloroadenosine (internal standard), dopamine, and (+/-)-isoproterenol (also an internal standard) were 91%, 99%, 88%, and 104%, respectively. The calibration curves for adenosine and dopamine were linear (r = 0.999, P less than 0.01) over the respective concentration ranges of 0.10 to 2.00 mg/L and 0.05 to 1.00 mg/L. Analytical precisions, assessed by the within-day and the day-to-day CVs, were 4.5% and 6.5% for adenosine, and 5.1% and 6.6% for dopamine, respectively. The mean (+/- SD) concentrations of adenosine (1.27 +/- 0.73 mg/L) and dopamine concentrations (0.38 +/- 0.25 mg/L) measured in urine from 19 healthy subjects agreed well with those previously reported.
Creatine kinase isoforms in ischemic heart disease.
Authors: Wu A H
Published: January 2020

The MM and MB isoenzymes of creatine kinase exist in serum as a collection of at least three major MM and two major MB isoforms. Each of these are derived from single tissue MM and MB isoforms, which are converted to these other forms by carboxypeptidase N after their release from necrotic skeletal and myocardial tissue. Measurement of the MM isoforms in ischemic heart disease is useful for early diagnosis of acute myocardial infarction and for the noninvasive determination of coronary artery reperfusion for infarction patients receiving thrombolytic therapy. Because MM is also released in acute skeletal-muscle disease, MB isoform measurements may have the highest clinical sensitivity. These determinations are important for providing objective information to cardiologists who need to make critical decisions concerning the management of these patients. I review the procedures for treating patients with myocardial infarction, the potential role of CK isoforms, and the methods currently available for isoform analysis, including high-resolution electrophoresis, isoelectric and chromatofocusing, and liquid chromatography. Rapid and highly sensitive methods are needed for implementation of CK-MM and MB isoforms for prospective emergency determinations for patients with acute myocardial infarction.
Preparation of fecal samples for assay of volatile fatty acids by gas-liquid chromatography and high-performance liquid chromatography.
Authors: Chen H M , Lifschitz C H
Published: January 2020

We describe a procedure for preparing fecal samples for determination of volatile fatty acids (VFAs) by gas-liquid chromatography (GLC) and "high-performance" liquid chromatography (HPLC). The simple, one-step procedure involves only ultrafiltration through a membrane with a molecular-mass cutoff of 3000 Da. As revealed by the GLC chromatograms, ultrafiltration appears to be as effective as steam distillation in sample clean-up. It also enables higher, more reproducible analytical recoveries of long-chain VFAs. The VFA content of the filtrate can also be measured by HPLC. Use of the ion-exclusion mechanism completely resolves isobutyric acid and butyric acid on a cation-exchange column. The mean (+/- SD) percentage distribution values of VFAs (measured by GLC) from five healthy subjects were 56.0 +/- 3.5 (acetic acid), 17.0 +/- 5.3 (propionic acid), 2.9 +/- 1.5 (isobutyric acid), 18.8 +/- 5.8 (butyric acid), 2.3 +/- 1.2 (isovaleric acid), and 2.9 +/- 0.8 (valeric acid).
Thermal inactivation of L-thyroxin.
Authors: Wortsman J , Papadimitriou D C , Borges M , Defesche C L
Published: January 2020

We assessed the extent of inactivation of L-thyroxin induced by exposure to heat in the presence of two vehicles. Preparations of L-thyroxin in the dry powder form, or dispersed in the solvents propylene glycol (water-like) or ethoxylated castor oil (oil-like), were heated at temperatures ranging from 65 to 160 degrees C, for 5- to 15-min periods. Heating L-thyroxin to a temperature below that of cooked bovine ground meat (72 degrees C) produced less than 10% degradation. Thermal degradation was pronounced only above 90 degrees C, and was almost completed at 160 degrees C. L-Triiodothyronine was the only thermal degradation product identified after L-thyroxin was heated at 125 degrees C. In a separate experiment we measured the melting point of L-thyroxin, 148.81 degrees C. This value agrees closely with the observed thermal sensitivity. We conclude that L-thyroxin is not significantly degraded under conditions encountered during cooking of ground bovine meat for short times at moderate temperatures.
Rapid purification of creatine kinase MB isoenzyme on preparative polyacrylamide slabs.
Authors: Geng J G , Chen H Z , Yang Y F , Qian Z H , Zhong L M
Published: January 2020

We describe a procedure for purification of creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) from human cardiac muscle by preparative electrophoresis on polyacrylamide gel. From a 50-g portion of human myocardium we isolated 21 mg of CK-MB, which had a specific creatine kinase activity of 405 kU/g. The CK-MB exhibited an enzyme band on polyacrylamide gel electrophoresis (PAGE) with staining for enzyme activity. The preparation showed single protein bands on sodium dodecyl sulfate--PAGE, pore gradient electrophoresis, and isoelectric focusing electrophoresis, the relative molecular masses of the subunit and of the whole enzyme being 43,000 and 86,000, respectively, and the isoelectric point being 5.0. In addition, the purified CK-MB showed desirable immunological specificity and affinity (K = 2.4 x 10(11) L/mol) when measured by radioimmunoassay.
Apolipoprotein E phenotype determined by agarose gel electrofocusing and immunoblotting.
Authors: McDowell I F , Wisdom G B , Trimble E R
Published: January 2020

Polymorphism at the apolipoprotein E (ApoE) locus is an important factor in the development of remnant (Type III) hyperlipidemia and also influences the distribution of cholesterol concentrations in the population. The new method for ApoE phenotyping described here gives good results with simple apparatus. Serum (10 microL) is digested with sialidase (EC 3.2.1.18), delipidated, and redissolved in 6 mol/L urea. Electrofocusing is carried out in agarose, followed by immunoblotting with a monoclonal antibody to ApoE and an anti-immunoglobulin-peroxidase conjugate. Sialidase-catalyzed digestion effectively removes sialated forms of ApoE, which eases interpretation. This method can be used in nonspecialist laboratories and is particularly suited for assay of large numbers of samples.
Diagnostic test for mucopolysaccharidosis. II. Rapid quantification of glycosaminoglycan in urine samples collected on a paper matrix.
Authors: Whitley C B , Draper K A , Dutton C M , Brown P A , Severson S L , France L A
Published: January 2020

The direct 1,9-dimethylmethylene blue (DMB) method for quantifying sulfated glycosaminoglycan (GAG) in urine (Clin Chem 1989; 35:374-9) has been adapted to a convenient means for sample collection and transport as a test to identify individuals with mucopolysaccharidosis (MPS) storage diseases. Results correlated moderately well (r = 0.85) with those of a commonly used, but more laborious, quantitative method. In studying factors to maximize differentiation of pathological from normal values, we found that GAG excretion (expressed as milligrams GAG per gram creatinine) fits a logarithmic function with respect to age and varies markedly below age five years. This must be considered in developing normative values and forming diagnoses. Of 112 separate urine specimens obtained from 41 MPS patients representing the major MPS diseases, glycosaminoglycan excretion by all exceeded that for age-matched normal individuals. The convenience of this method allowed us to establish the first normative values for three-week-old infants (n = 435) found to have a mean glycosaminoglycan excretion of 179 (SD 86.3) mg of GAG per gram of creatinine. This method improves the diagnostic capability for those MPS diseases that have been particularly difficult to identify (Sanfilippo's syndrome and Morquio's syndrome), and may also provide a test for other disorders with previously unrecognized abnormal excretion of glycosaminoglycan (e.g., mucolipidosis and acromesomelic dysplasia). Most importantly, this MPS diagnostic test is unique in its suitability for mass screening of newborn infants.
Oxalate is overestimated in alkaline urines collected during administration of bicarbonate with no specimen pH adjustment.
Authors: Lemann J , Hornick L J , Pleuss J A , Gray R W
Published: January 2020

We compared measurements of daily urine oxalate excretion in urines collected at the prevailing urine pH with measurements of urine oxalate excretion in urines collected into 20 mL of 6 mol/L HCl. We studied eight healthy adults fed constant diets. Urines were collected during control conditions and, in each subject, during the administration of NaCl, KCl, NaHCO3, or KHCO3, 90 mmol/day. Daily urine oxalate excretion calculated for collections made in acid averaged 271 (SD 79) mumol/day and did not vary with any of the salt supplements. When urines were collected at ambient urine pH (average 5.94, SD 0.23) during control conditions, and during the administration of NaCl or KCl, urine oxalate excretion averaged 263 (SD 88) mumol/day, a value not different from that for collections in acid. However, when urine was collected with no pH adjustment during NaHCO3 or KHCO3 administration (average pH 6.90, SD 0.14), apparent urine oxalate excretion averaged 398 (SD 132) mumol/day, significantly (P less than 0.025) exceeding the mean observed when urines were collected in acid. Moreover, the percentage increase in apparent oxalate excretion increased with urinary pH. These observations reinforce recommendations that urine specimens for measurement of oxalate be collected in acid to avoid the increase in apparent oxalate content that occurs during collection of alkaline urines. This increase presumably results from the well-known in vitro nonenzymatic conversion of ascorbate to oxalate.
Multi-factor designs. II. A design for identifying instruments with sample-to-sample carryover and drift.
Authors: Schlain B , Krouwer J S
Published: January 2020

We describe a nearly orthogonal two-level design that involves use of a weighted analysis to estimate drift and very low amounts of sample-to-sample carryover simultaneously. Identifying systematic errors from these sources is especially important for assays of analytes presenting a large range and with a medical decision point close to zero. The design is illustrated with data for thyrotropin, where, in one run with 32 samples, 0.08% carryover was detected in the presence of concentration-dependent negative drift.
Multi-center study of a new technique for measuring free thyroxin in serum.
Authors: Izembart M , Sala M , Baldet L , Schlumberger M , Deltour G
Published: January 2020

In a multi-center trial we evaluated the accuracy of a new assay kit for free thyroxin (T4), the Behring free T4 RIAgnost, in 1036 subjects: 379 normal subjects, 536 patients with thyroid dysfunction, and 121 subjects with no thyroid dysfunction but with conditions that potentially could interfere with the assay. The kit combines immunoextraction and the use of a modified tracer. Although some limitations remained in using a direct assay method for free T4 in certain nonthyroid conditions, this test was superior to one based on the use of a T4 analog. This kit seems to be very accurate for the diagnosis of untreated thyroid pathologies.
Factors affecting a cyanogen bromide-based assay of thiamin.
Authors: Wyatt D T , Lee M , Hillman R E
Published: January 2020

We analyzed extensively a modified thiochrome method for thiamin analysis. Acid phosphatase (EC 3.1.3.2) from potato was superior to either alpha-amylase or acid phosphatase from wheat germ as a dephosphorylating agent. Timing of cyanogen bromide exposure was important, but the assay had good precision and accuracy. The standard curve was linear from 10 to 3000 nmol/L. The within-run and between-run coefficients of variation for total thiamin in whole blood were 3.6% and 7.4%, respectively. Analytical recoveries for low, intermediate, and high additions of thiamin to whole blood were 93-109%. Sample yield was increased by 41% (+/- 29% SD) with pre-assay freezing. Samples were stable for two days at room temperature, for seven days when refrigerated, and for two years when frozen. Previously unreported interference was seen with penicillin derivatives, and with several commonly used diuretic and antiepileptic medications. This assay may be suitable for population screening; 200 samples could be analyzed weekly at a cost of +0.20 per sample.
A clinical chemistry analyzer evaluated by NCCLS guidelines for use in a military field laboratory unit.
Authors: Sullinger J , Garrett P E
Published: January 2020

In a previous comparison study of "dry chemistry" desktop analyzers, the ChemPro 1000 (Arden Medical Systems) was one of several instruments found suitable for field use. We have now evaluated the linearity, accuracy, and precision of the ChemPro 1000, according to NCCLS Document EP 10-P. We also compared results with those by the SMAC (Technicon) and the Nova 9 (Nova Biomedical) for electrolytes, serum urea nitrogen, and ionized calcium in field and laboratory environments. The precision (CV) of the ChemPro was within acceptable ranges for dry chemistry desktop analyzers for all analytes tested. This instrument is a suitable and reasonable alternative to manual chemistry or to large, automated instrumentation in a field environment.
Electrophoretic examination of proteinuria in Lowe's syndrome and other causes of renal tubular Fanconi syndrome.
Authors: Papadopoulos N M , Costello R , Charnas L , Adamson M D , Gahl W A
Published: January 2020

Urine samples from 26 patients with five different causes of renal tubular Fanconi syndrome were examined by zone electrophoresis on agarose gel and immunofixation. The tubular disorders associated with Lowe's syndrome, cystinosis, and idiopathic Fanconi syndrome exhibited urine protein electrophoretic characteristics that differentiated them from normal and from each other. In particular, Lowe's syndrome urine exhibited four discrete bands in the gamma globulin zone. Electrophoresis of urinary proteins may be useful in distinguishing among the different metabolic disorders causing renal tubular Fanconi syndrome.
Urinary neopterin concentrations vs total neopterins for clinical utility.
Authors: Fuchs D , Milstien S , Krämer A , Reibnegger G , Werner E R , Goedert J J , Kaufman S , Wachter H
Published: January 2020

Neopterin measurements are especially useful as an early marker in (e.g.) allograft rejections and in patients infected with human immunodeficiency virus type 1 (HIV-1). An increased concentration of total neopterins (neopterin + dihydroneopterin) is also a significant marker in patients with HIV-1 infection. In this study we compared concentrations of neopterin and total neopterins in urine samples from 77 homosexual men with and 73 without established HIV-1 infection. HIV-1-seropositive homosexual men had higher concentrations of neopterin and total neopterins (and 7,8-dihydroneopterin) in their urine than did those who were HIV-1-seronegative, and there was a close correlation between neopterin and total neopterins. Both neopterin variables correlated inversely with CD4+ T-cell counts and CD4+/CD8+ T-cell ratios but not with CD8+ T-cell counts in the HIV-1-seropositive men. Our data indicate that measurements of neopterin and total neopterins are of almost equal potential for clinical diagnosis. However, when measuring total neopterins, which includes oxidation of 7,8-dihydroneopterin to neopterin, more strict requirements of sample collection and handling are necessary to avoid degradation of the 7,8-dihydro derivative.
Chemiluminescent enzyme immunoassay of alpha-fetoprotein based on an adamantyl dioxetane phenyl phosphate substrate.
Authors: Thorpe G H , Bronstein I , Kricka L J , Edwards B , Voyta J C
Published: January 2020

We have evaluated a new chemiluminescent substrate for the alkaline phosphatase (EC 3.1.3.1) label used in a Hybritech Tandem-E immunoassay of alpha-fetoprotein (AFP). The new substrate, adamantyl 1,2-dioxetane phenyl phosphate (AMPPD), emits light at 477 nm when acted upon by the enzyme. Detection limits for AFP with this method were 33 ng/L (mean of 20 replicates of the zero standard + 2 SD) and 470 ng/L (twice background). Between-batch CVs ranged from 4.31% to 9.60% for AFP in the range 29.1-132.0 micrograms/L. Comparison of results for 49 specimens assayed with use of the chemiluminescent kit and a colorimetric version of the AFP assay gave statistical values as follows: slope = 0.88, intercept = 4.19, and r = 0.94.
Sensitive, simple staining method for use in electrophoretic determination of amylase isoenzymes in serum.
Authors: Mashige F , Hisae N , Toyota S , Yoshinoya S , Ohkubo A
Published: January 2020

We have developed a sensitive and simple staining method for use in electrophoretic analysis of serum alpha-amylase (EC 3.2.1.1) isoenzymes. The principle of this method is as follows. alpha-Amylase hydrolyzes 4-nitrophenylmaltoheptaoside to generate oligosaccharide, which is then converted to gluconolactone in the presence of oligosaccharide dehydrogenase (no EC no. assigned), with concomitant reduction of 1-methoxy-5-methylphenazinium methylsulfate (1-m-PMS) to 1-m-PMSH. The hydrogen in 1-m-PMSH is then transferred to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide to yield formazan. Each of the isoenzymes can then be measured densitometrically. The mean (and SD) values for total amylase, P1, S1, and S2 as determined by this method with sera from 25 healthy adults in fasting were 251 (64), 104 (35), 126 (40), and 22 (11) U/L, respectively. Between-assay CVs (n = 10) for determinations of P1, S1, and S2 were 3.54%, 4.03%, and 7.01%, respectively.
Automated enzyme immunoassay for lutropin with the Abbott IMx analyzer.
Authors: Ford K A , Baker H N , Baar J G , Balay D , Marlewski D , Venetucci M , Ogunro E A
Published: January 2020

An automated enzyme immunoassay for human lutropin for use with the Abbott IMx analyzer is described. The assay provides results in approximately 40 min with a sensitivity of 0.25 int. units of LH per liter for up to 23 serum or plasma samples. Cross-reactivity with follitropin (2000 int. units/L) and thyrotropin (2 int. units/L) was negligible; it was 0.016% with human choriogonadotropin (1 X 10(6) int. units/L). There was no interference by high concentrations of bilirubin (0.5 g/L), hemoglobin (7.50 g/L), or triglycerides (13.5 g/L). Intra-, inter-, and total assay CVs were less than or equal to 3.75%, less than or equal to 7.1%, and less than or equal to 7.94%, respectively. Values obtained with the IMx correlated well (r = 0.98, n = 194) with values obtained with Diagnostic Products' LH Double Antibody RIA, and Serono's LH MAIAclone assay. This assay should be useful for small to medium-size laboratories involved in the clinical diagnosis of reproductive pathology.
A two-site immunoenzymometric assay of 52-kDa pro-cathepsin D, and its use in human breast diseases.
Authors: Freiss G , Vignon F , Pau B , Paolucci F , Rochefort H
Published: January 2020

After isolating monoclonal antibodies specific for the 52-kDa precursor of cathepsin D (cath-D), which is secreted in excess in both hormone-dependent and hormone-independent breast cancer, we developed a two-step double-determinant immunoenzymometric assay that is specific for this pro-enzyme. The assay combines the use of a monoclonal antibody specific for the precursor and bound to microtiter plates, and a second antibody directed against a smaller processed form of the mature enzyme, coupled to alkaline phosphatase. The specificity of the assay relies on separate and sequential additions of the antigen and the conjugated second antibody. It allows rapid measurement of the analyte in plasma and cytosols of normal and neoplastic mammary tissues, with a detection limit of 5 fmol and a maximal interassay coefficient of variation of 9%. This assay is particularly useful for tissue cytosol samples where the pro-enzyme form co-exists with large quantities of the mature processed forms of the enzyme. Comparative assays of 52-kDa pro-cath-D and total cath-D in cytosols of breast cancers and benign mastopathies indicate that the present assay better discriminates between benign and cancerous mammary tumors.
A simple liquid-chromatographic method for measuring vitamin B6 compounds in plasma.
Authors: Edwards P , Liu P K , Rose G A
Published: January 2020

This relatively simple high-performance liquid chromatographic (HPLC) method for measuring all seven known forms of vitamin B6 in plasma from individuals supplemented with pyridoxine hydrochloride shows good analytical recovery (85-98%) and precision. Within-run and between-run CVs for plasmas supplemented with standards were 4% and 7%, respectively. The major forms of B6 found in unsupplemented plasma from normal subjects were pyridoxal phosphate and 4-pyridoxic acid, with pyridoxal just detectable. The HPLC procedure correlated well (r = 0.94) with a modification of an enzymatic method involving apotryptophanase (Anal Biochem 1972;45:567-76) for measuring plasma pyridoxal phosphate, and also (r = 0.94) with a routine method for determining 4-pyridoxic acid in urine (Clin Chem 1964;10:479-89). Elimination of pyridoxine from the plasma of both normal and hyperoxaluric individuals was shown to be very rapid, with half-lives (t1/2) of 45 and 40 min, respectively. Finally, we present evidence for the existence of two other forms of B6 and discuss the possibility of a new metabolic pathway in vitamin B6 metabolism.
Measuring carboxypeptidase A activity with a centrifugal analyzer: analytical and clinical considerations.
Authors: Kazmierczak S C , Van Lente F
Published: January 2020

This adaptation of a commercially available kit for automated measurement of carboxypeptidase A (CPA; EC 3.4.17.1) activity in serum with the Cobas Bio centrifugal analyzer extends the linear range to an activity concentration of 82 U/L. Results obtained by the described method correlated closely (r = 0.98) with those by the manual kit method. The reference interval for 150 apparently normal individuals was 0.12-0.91 U/L. Total CVs of the method ranged from 4.0% to 13.1%. Bilirubin and glucose decreased the CPA activity in serum by as much as 98% and 26%, respectively. Substantial CPA activity was found in pancreatic tissue, with little activity in intestinal tissue. CPA activity was not as widely distributed in extra-pancreatic tissues as were amylase and lipase activities. Peak activities of CPA, amylase, and lipase in the sera of patients with acute pancreatitis were significantly correlated (r = 0.45 to 0.78, P less than 0.05-0.01). The optimized diagnostic efficiency of CPA for acute pancreatitis was 0.85 at a cutoff value of 5 U/L. Amylase and lipase exhibited similar optimized efficiencies, and parallel testing did not significantly improve diagnostic accuracy. We conclude that automated analysis for CPA activity, even in the absence of interferences, does not add to the diagnostic information provided by the widely available assays for amylase and lipase activity.
A longitudinal study of thyroid function in pregnancy.
Authors: Price A , Griffiths H , Morris B W
Published: January 2020

We undertook a prospective longitudinal study of thyroid function in 36 pregnant women. There were significant increases in thyroxin-binding globulin, thyrotropin, and triiodothyronine. Albumin, free thyroxin (measured by an analog and a nonanalog method), and the free thyroxin index were significantly decreased. Results for the free thyroxin methods were correlated with each other in each trimester. We could find no evidence for artifacts related to albumin or thyroxin-binding globulin with either method for free thyroxin.
Choosing quality-control systems to detect maximum clinically allowable analytical errors.
Authors: Linnet K
Published: January 2020

Critical systematic and random analytical errors for 17 common clinical chemical components were estimated from published values for analytical imprecision, biological variation, and "medically important changes." Appropriate quality-control systems for these analytes are discussed on the basis of power considerations. The simple rule 1(3)s, with one control per run, is minimally sufficient for the analytes (about one quarter of those considered here) for which the magnitude of critical error is at least 3 analytical standard deviations. The more powerful rule 1(2)s, with one control per run, is the minimal requirement for analytes for which critical errors are about 2 analytical standard deviations; these are about half the remaining analytes. Greater power values are achieved by using multiple rules based on several controls per run. In general, this study does not support the view put forward by some authors that the quality-control rules in use today are too restrictive.
Determination of physostigmine in plasma and cerebrospinal fluid by liquid chromatography with electrochemical detection.
Authors: Unni L K , Hannant M E , Becker R E , Giacobini E
Published: January 2020

Physostigmine (Phy) was determined in plasma and cerebrospinal fluid (CSF) by HPLC with electrochemical detection, with use of a normal-phase column and methanolic sodium acetate buffer, pH 4.6. The detection limit of the method was 0.5 micrograms/L for a 2-mL sample of plasma or 0.5 mL of CSF. Analytical recovery of Phy in the range from 0.5 to 40 micrograms/L was 60% (SD 5%) for plasma and 78% (SD 8%) for CSF. Excellent chromatographic separation of Phy without column deterioration during extended usage and constant recovery for a wide range of Phy concentrations makes the routine monitoring of plasma from patients with Alzheimer's disease economically feasible. Using our method, we measured Phy in 13 such patients' plasmas at 105 and 135 min after a 135-min intravenous infusion of 300, 600, and 900 micrograms of Phy per square meter of body surface. Mean values significantly increased with dose (P = 0.001), but differences between 105 and 135 min (P = 0.229) or between dose and time (P = 0.949) were not significant.
Fluorescence polarization immunoassay of urinary 5-hydroxy-3-indoleacetic acid.
Authors: Brashear J , Zeitvogel C , Jackson J , Flentge C , Janulis L , Cantrell L , Schmidt B , Adamczyk M , Betebenner D , Vaughan K
Published: January 2020

Fluorescence polarization immunoassay of 5-hydroxy-3-indoleacetic acid in urine is described and compared with liquid chromatography (electrochemical detection) and colorimetry. Reports of in-house performance data and results of clinical trials are included to emphasize the usefulness of the assay for routine work.
Kinetic study of the Jaffé reaction for quantifying creatinine in serum: 2. Evaluation of buffered reagent and comparison of different data-processing options.
Authors: Bacon B L , Pardue H L
Published: January 2020

Here we describe the evaluation of several data-processing options for the kinetic determination of creatinine by use of the Jaffé reaction. Data-processing options evaluated include initial-rate, two-point fixed-time, rate at t = k-1, and multipoint curve-fitting predictive methods. We evaluated these options for a buffered formulation of the Jaffé reagent and studied the effects of potential interferents, including glucose, acetoacetate, bilirubin, and albumin, on each option. To reduce effects of bilirubin, we evaluated the inclusion of a preoxidation step with ferricyanide. All the data-processing options gave good precision and linearity between the measurement objective and creatinine concentration. However, differences between slopes of calibration plots in aqueous and serum matrices ranged from a high of +60% for the two-point, fixed-time method to a low of -11% for the curve-fitting, predictive method. Standard additions of creatinine to sera were quantified reliably (yielding 96% to 102% of target values) by the predictive method and less reliably (62% to 102%) by the other methods. We conclude that the predictive method has the potential to yield the most reliable results for creatinine.
Changes in creatine kinase activity in the course of acute myocardial infarction.
Authors: Weinberger I , Fuchs J , Rotenberg Z , Davidson E , Harel D , Agmon J
Published: January 2020

Peak activity of creatine kinase (CK; EC 2.7.3.2) and its decline were determined in 380 patients with acute myocardial infarction (AMI) whose CK values had peaked after admission to the hospital. During hospitalization, 26 patients either died (14 patients) or experienced nonfatal re-infarction (12 patients). In 22 of these 26 patients CK activity decreased by less than 50% within 48 h after the peak value was measured. In all patients who did not die or develop re-infarction, CK activity decreased by greater than 50% during the 48 h after the peak. Evidently the rate of decline of CK (i.e., whether more than or less than 50%) from its peak value during the 48 h after AMI may be helpful in assessing which patients are at high risk for developing re-infarction or dying.
Oligoclonal banding in serum from heart-transplant recipients.
Authors: Monk J , Calvin J , Price C P , Wreghitt T G
Published: January 2020

Sera from heart-transplant patients on immunosuppressive drugs frequently exhibit pronounced oligoclonal banding patterns. There is a strong association between the appearance of these immunoglobulins and infection with cytomegalovirus (CMV) in these patients. Fainter bands were seen both in patients with CMV infection and with various other infections. We saw no oligoclonal banding in electrophoretograms of sera of heart-transplant patients free of known infection.
A self-consistent set of reference values for 23 clinical chemical analytes.
Authors: Spichiger U E , Vonderschmitt D J
Published: January 2020

Heparinized plasma of 528 blood donors was subjected to the 23 most frequently ordered chemical and enzymatic tests. The central fraction of the distribution of all results for each test was estimated. Out of the 528 donors a reference population has been selected. Because of the lack of other criteria, the result for any test of a blood donor was selected as a value belonging to the reference population if the results for the other 22 analytes of this particular donor lay within their own central fraction. On this basis an iterative procedure for the selection was programmed, considering the interaction between tests. The procedure was stopped when the reference limits for all 23 tests were converging. Fractions from 0.90 to 0.98 were applied to results for men and women donors separately. The elimination procedure and the criteria to select the best fitted fraction are discussed. The derived reference intervals are designated a "self-consistent set of reference values."
Leukotriene B4 is measurable in serum of smokers and nonsmokers.
Authors: Thornton W H , Adelstein E H , Edes T E
Published: January 2020

Leukotriene B4 (LTB4), an arachidonic acid metabolite released by neutrophils and macrophages, helps regulate host immune response to antigenic stimulation. LTB4 affects the chemokinesis, aggregation, and enzyme release of neutrophils and stimulates activity of cytotoxic T cells, natural killer cells, and suppressor T cells. LTB4 also has a positive affect on the margination of monocytes and macrophages in the lung in response to inflammatory stimuli. Cigarette smoking represents an inflammatory stimulus in the lung and affects (decreases) the in vitro release of LTB4 by alveolar, macrophages in comparison with that by alveolar macrophages of nonsmokers. By utilizing a sensitive and specific radioimmunoassay we have detected LTB4 concentrations in serum from smokers and nonsmokers. Furthermore, our preliminary data show mean LTB4 concentrations in the serum of smokers to be nearly 60-fold greater than those in nonsmokers, 211 (SEM 35) vs 3.6 (SEM 1.5). Because systemic quantities of LTB4 are now measurable, quantification of this immune system regulatory may be useful in evaluating inflammatory disease states.
Automated fluoroimmunoassay of theophylline and valproic acid by flow-injection analysis with use of HPLC instruments.
Authors: Allain P , Turcant A , Prémel-Cabic A
Published: January 2020

For automated determination of theophylline and valproic acid by use of Ames' fluoroimmunoassays we used a high-pressure liquid-chromatographic system consisting of a pump, a robotic unit (Gilson 231/401, to prepare and inject the samples into the flowing carrier), and a fluorometer with a 10-microL flow cell. Results correlated well with those of conventional liquid- and gas-chromatography (r less than 0.96). The between-run CV is about 5%. In comparison with the manual method, the volume of reagents (and thus the cost per analysis) was decreased by eightfold.
Automated determination of urinary Na+, K+, chloride, inorganic phosphate, urea, and creatinine without sample dilution, with the "RA-XT".
Authors: Fesus P D , Pressac M , Braconnier F , Aymard P
Published: January 2020

We describe how concentrations of chloride, urea, inorganic phosphate, and creatinine in urine can be measured directly, without manual sample dilution, in a discrete analyzer (the Technicon "RA-XT"). These methods were accurate for concentrations of chloride up to 280 mmol/L, urea up to 500 mmol/L, inorganic phosphate up to 50 mmol/L, and creatinine up to 30 mmol/L. CVs are less than 3% nd results correlate well with those obtained by continuous-flow analysis (SMA-II). All these reagents are stable at room temperature for three weeks. Analyses are easy to perform and infrequent calibration is required.
Effect of hematocrit and added heparin on ionized calcium in capillary blood samples from neonates.
Authors: Nelson N , Ohman S , Larsson L
Published: January 2020

Sampling of capillary blood for determination of ionized calcium (Ca2+) in neonates requires that extra heparin be added to prevent clotting in the sampling tube and (or) in the Ca2+ analyzer. Because the additive dissolves in the plasma compartment, different hematocrit (erythrocyte volume fraction, EVF) values may cause different results for Ca2+. To study the effect of EVF and heparin additive, we repeatedly removed plasma, thereby increasing the EVF. These samples with different EVF's were aspirated into commercial capillary tubes containing heparin and, according to our routine procedure, an additional 10 microL (approximately 0.9 int. unit) of sodium heparin. We found a negative bias of 0.05-0.09 mmol/L in Ca2+, depending on the EVF. Adding saline instead of heparin gave the same effect, indicating that this bias was entirely due to dilution. We suggest compensating for this by adding 0.09 mmol/L to the actual value for ionized calcium when EVF exceeds 70%. The increase in Ca2+ in neonates on days 1 to 5 postpartum is physiological and not an effect of change in EVF.
Immunoradiometric assay of carcinoembryonic antigen with use of avidin-biotin labeling.
Authors: Peters J , Schmidt-Gayk H , Peters B , Armbruster F P , Quentmeier A , Mathias D
Published: January 2020

In evaluating an enzyme-linked immunoassay of carcinoembryonic antigen (CEA) we found that the IgG fraction of polyclonal anti-CEA antibodies (DAKO) bound very well to the walls of polypropylene test tubes. We therefore developed an immunoradiometric CEA assay based on this binding of polyclonal anti-CEA antibody. We biotinylated a commercially available monoclonal antibody (Hybritech) and bound this to the CEA-anti-CEA bound to the tube wall. For detection we used 125I-labeled streptavidin. In comparison with several immunoassays for CEA this system offered several advantages such as greater linearity of the standard curve (from 0 to 74 micrograms/L), a steeper dose-response curve, and smaller coefficients of variation in the clinically useful range. This assay system may be used for other large molecules, so that only one tracer, the 125I-labeled streptavidin, has to be labeled; thus the technique seems suited for several different assays.