bluuebunny/crossref_metadata_2025 huggingface dataset:
Automated quantification of choriogonadotropin: analytical correlation between serum and urine with creatinine correction.
Authors: Wu A H , Wong S S , Waldron C , Chan D W
Published: January 2020

We evaluated the Boehringer Mannheim Diagnostics ES 600 automated immunoassay system for measuring choriogonadotropin (hCG) in human serum, plasma, and urine. The ES 600, an automated sample-selective, multibatch analyzer, is based on immunoenzymometric coated-tube technology. Interassay CVs for assay of both serum and urine ranged from 2% to 16%. The analytical sensitivity was 0.5 int. unit/L. Results for serum correlated well with qualitative "Icon" and quantitative "Tandem" assays (Hybritech). In addition, results for serum and urinary hCG correlated well when the latter was expressed in terms of creatinine excretion. These results suggest that determination of hCG in urine can be correlated with those in serum for use as a marker for chorionic tumors or for screening abnormal pregnancies, where the rate of hCG production may be important.
Multiple overnight urine collections may be used for estimating the excretion of electrolytes and creatinine.
Authors: Knuiman J T , van Poppel G , Burema J , van der Heijden L , Hautvast J G
Published: January 2020

We studied the excretion of sodium, potassium, calcium, magnesium, and creatinine in overnight and 24-h urines collected over a period of seven consecutive days from 28 Dutch boys, ages eight and nine years. The correlation coefficients for the relation between true mean overnight and true mean 24-h excretion ranged between 0.94 and 1.00 for sodium, calcium, magnesium, and creatinine and was equal to 0.61 for potassium. Generally the within-person coefficients of variation for overnight excretions (range, 33-52%) were greater than for 24-h excretions (range 16-35%). We conclude that overnight collections may replace 24-h collections in the case of young boys, but that generally more overnight than 24-h urine specimens are required to achieve a similar degree of precision. The exact number of urine specimens required varies with the aims of the study.
Automated determination of drugs in serum by liquid chromatography with column-switching. I. Separation of antiepileptic drugs and metabolites.
Authors: Matsumoto K , Kikuchi H , Kano S , Iri H , Takahashi H , Umino M
Published: January 2020

This is a fully automated system for determining six common antiepileptic drugs and two principal metabolites of carbamazepine in serum. It is based on "high-performance" liquid chromatography (HPLC), with column switching. TSKprecolumn BSA-ODS and TSKgel ODS-120A (both from Toyo Soda) were used as the precolumn and analytical column, respectively. The former contains octadecylsilyl resins treated with bovine serum albumin (BSA), and does not adsorb macromolecules such as serum proteins but retains small lipophilic molecules such as antiepileptic drugs. Serum samples are directly injected onto the precolumn. After washing out the serum proteins from the precolumn with sodium phosphate buffer, we switch the column connections to introduce the retained substances onto the analytical column and elute with a step-gradient of acetonitrile/sodium phosphate buffer. The high analytical recovery (95-102%) and the reproducibilities (CV less than 5% within-run) indicate that this system is suitable for use in theraputic drug monitoring in clinical laboratories.
Changes in carnitine in polymorphonuclear leukocytes, mononuclear cells, and plasma from patients with inflammatory disorders.
Authors: Adlouni H A , Katrib K , Férard G
Published: January 2020

After finding relatively large amounts of carnitine in polymorphonuclear leukocytes and mononuclear cells from healthy subjects, we studied carnitine status in these cells and plasma from 20 patients with inflammatory disorders subsequent to multiple trauma and (or) head injury. The nonesterified carnitine content in polymorphonuclear leukocytes from patients significantly exceeded that in healthy subjects, while it was significantly decreased in mononuclear cells. In addition, the acylcarnitine content of both types of cells from patients was significantly increased. The total carnitine of polymorphonuclear leukocytes from patients was significantly increased, while that in mononuclear cells was unchanged, as compared with healthy subjects. In plasma from patients, nonesterified carnitine was extremely decreased, while both short-chain acylcarnitine and long-chain acylcarnitine were significantly increased. More than half of the carnitine was acylated in polymorphonuclear leukocytes and mononuclear cells in all patients tested, less than half in these cells from healthy subjects. Also, the presence of infection in these patients does increase, but not significantly, the nonesterified and acylcarnitine of both polymorphonuclear leukocytes and mononuclear cells from these patients.
Immunoturbidimetry of urinary albumin: prevention of adsorption of albumin; influence of other urinary constituents.
Authors: Bakker A J
Published: January 2020

I describe a simple, rapid immunoturbidimetric assay for low concentrations of albumin in urine (2 to 260 mg/L). However, in this assay, the human serum albumin (HSA) in the standards binds nonspecifically to the polystyrene or glass tubes. This nonspecific binding cannot be prevented by adding bovine serum albumin (BSA) to standards, because the anti-HSA antibody cross reacts with BSA. Adding Triton X-100 (1 mL/L) to standards effectively prevents this nonspecific binding of HSA from standards to both polystyrene and glass tubes. High concentrations of compounds found in urine from normal and diabetic subjects do not interfere with this assay if pH extremes can be avoided. The between-day CV is 4.8% at means = 18.8 mg/L and 2.0% at means = 183.1 mg/L. Measurements by this immunoturbidimetric method (y) correlate well with those obtained by a radioimmunoassay (x): y = 1.078x - 0.141 mg/L (n = 98; r = 0.984) and with those obtained by a radial immunodiffusion method (x'): y = 1.026x' - 0.117 mg/L (n = 98; r = 0.983). Urinary excretion of albumin by 25 healthy, nondiabetic subjects was less than 8 micrograms/min.
Nutritional status of patients with acquired immunodeficiency syndrome.
Authors: Huang C M , Ruddel M , Elin R J
Published: January 2020

Nutritional status may be an important factor in the prognosis of morbidity and mortality. We assessed the nutritional status of individuals seropositive for human immunodeficiency virus (HIV) (as confirmed by Western blot) and of patients with AIDS, by determining the concentration in serum of total protein, albumin, prealbumin (transthyretin), and retinol-binding protein. HIV-seropositive individuals showed no significant difference from normal volunteers in values for prealbumin, albumin, and retinol-binding protein. Patients with AIDS showed significantly smaller prealbumin and albumin concentrations than did normal and HIV-positive individuals. There was no significant difference in the concentration of retinol-binding protein among the three groups. The concentration of total serum protein was significantly greater in HIV-positive individuals and in patients with AIDS than in normal individuals. Thus, the nutritional status of patients with AIDS may be a factor for morbidity and mortality.
Development of a direct assay for alpha-amylase.
Authors: Winn-Deen E S , David H , Sigler G , Chavez R
Published: January 2020

We describe a direct colorimetric assay for alpha-amylase, with 2-chloro-4-nitrophenyl-alpha-maltotrioside as substrate. Both human pancreatic and salivary amylase split this substrate without the use of helper enzymes, yielding free 2-chloro-4-nitrophenol, which is monitored at 405 nm. The performance of this reagent compares well with that of Pantrak Amylase (Behring Diagnostics) for both serum and urine samples. The reagent is very stable in dry powder form and is stable for one month at 2 to 8 degrees C after reconstitution. Because of the rapid color development and linear kinetics (less than 30 s), the assay is easily automated. Results can be obtained in less than 5 min.
Clinical variability of cyclosporine pharmacokinetics in adult and pediatric patients after renal, cardiac, hepatic, and bone-marrow transplants.
Authors: Clardy C W , Schroeder T J , Myre S A , Wadhwa N K , Pesce A J , First M R , McEnery P T , Balistreri W F , Harris R E , Melvin D B
Published: January 2020

The most important limitation associated with the clinical use of cyclosporine is the narrow therapeutic range between its efficacy and toxicity. Effective treatment is further complicated by significant variation in intrapatient and interpatient pharmacokinetics of the drug. We describe a practical approach to pharmacokinetic analysis that does not interfere with the cyclosporine dosage regimen or with clinical management of the patient. To optimize therapy, we individualized patient management by using noncompartmental pharmacokinetic analysis. Mean residence time (MRT) and volume of distribution at steady-state were calculated from data on concentration vs time after dose. We applied this approach to 24 kidney, 12 heart, 8 bone-marrow, 7 liver, and 5 pancreas transplants. Individualized requirements for cyclosporine dose and dosage interval can be predicted from these parameters. MRT is the most useful pharmacokinetic parameter, because it allows prediction of the optimal dosage interval.
Evaluation of an enzyme immunoassay kit for estrogen receptor measurement--report II.
Authors: Raam S , Vrabel D M
Published: January 2020

We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.
Measurement of plasma phenytoin by EMIT in the Monarch centrifugal analyzer: studies on the elimination of within-rotor drift.
Authors: Wenham P R , Barbour H M
Published: January 2020

We investigated the measurement of phenytoin in plasma by the EMIT method, in the Monarch centrifugal analyzer. When we used the standard protocol supplied by Instrumentation Laboratory, significant drift was observed across a full rotor loaded with 31 replicates of a single specimen. Although the cause remains obscure, the drift was eliminated by using a load-spin-reload-spin procedure. This makes it possible to analyze large batches of samples without excessive use of standards and reagents.
Studies on measurement of plasma magnesium: application of the Magon dye method to the "Monarch" centrifugal analyzer.
Authors: Barbour H M , Davidson W
Published: January 2020

The "Magnesium Liquid Stable Reagent Set" from Medical Analysis Systems, Inc., is evaluated. The method, which involves Magon dye binding and bichromatic absorbance measurements, was used in a Monarch centrifugal analyzer. Results were compared with those by atomic absorption spectrometry. The calibration curve for the Magon method is linear to 2.5 mmol/L, with a 2-microL sample volume. Analytical recovery of magnesium added to human plasma ranged from 95 to 102%. The working reagent is stable for at least five days at 15 degrees C. At concentrations of 0.54 and 1.20 mmol/L, the respective CVs were 2.15 and 3.60% within batch, and 3.13 and 3.24% between batch. We analyzed 150 clinical samples for magnesium by both methods. Absorbance readings at 520/600 nm rather than 520/690 nm improved the correlation (r = 0.9777 and r = 0.9428, respectively). Calcium, albumin, phosphate, or bilirubin did not significantly interfere.
Effect of nitroblue tetrazolium concentration on the fructosamine assay for quantifying glycated protein.
Authors: Chung H F , Lees H , Gutman S I
Published: January 2020

Experiments with nitroblue tetrazolium (NBT) at 0.25, 0.50, and 0.75 mmol/L confirmed that reactivity of 1-deoxy-1-morpholino-D-fructose, the standard, was more sensitive to reagent concentration than was protein ketoamine and demonstrated why an increase in NBT or a decrease in sample volume yields lower values for serum fructosamine. Analyses of clinical samples from diabetic and nondiabetic patients and from healthy subjects indicated that, with NBT at 0.25 mmol/L, discrimination between diabetics and other subjects was improved by changing the sample:reagent volume ratio from the usual 1:10 to 1:25 (9- to 12-min reading time). Discrimination improved further with NBT at 0.75 mmol/L and a 1:25 ratio but a later reading time (18-21 min); these conditions may minimize the effects of some but not all interferents.
Storage of whole blood: effect of temperature on the measured concentration of analytes in serum.
Authors: Rehak N N , Chiang B T
Published: January 2020

We measured the concentrations of 29 commonly measured analytes in fresh sera and in sera that had been stored as whole blood at seven different temperatures for 24 h. We determined the effect of storage temperature and prolonged contact with cell clot on the measured concentration of each analyte, with fresh serum as the control. Significant differences were observed for concentrations of creatinine, glucose, inorganic phosphorus, potassium, and both aminotransferases. The extent of these differences was temperature dependent. Values for the remaining 23 analytes examined were essentially unaffected by the storage.
Catecholamine content of human erythrocytes.
Authors: Altman R J , Smith C C , Betteridge J
Published: January 2020

We used high-performance liquid chromatography with electrochemical detection to measure the catecholamine content of human erythrocytes. The ratio of free norepinephrine to epinephrine was three to four times lower than that in plasma and four to seven times lower than that in platelets. This suggests differences in uptake, degradation, or conjugation of norepinephrine and epinephrine by erythrocytes, as compared with plasma and platelets. Erythrocyte free norepinephrine was significantly greater (P less than 0.01) in women than in men.
Automated nephelometry of fibrinogen: analytical performance and observations during thrombolytic therapy.
Authors: Hoffmann J J , Verhappen M A
Published: January 2020

We evaluated the performance of an automated nephelometric determination of fibrinogen, which is an integral part of the prothrombin time assay, in a new coagulation analyzer, the ACL-810 (Instrumentation Laboratory). Results were compared with those by a total clottable protein assay and with the thrombin clotting time assay for fibrinogen. In normal and slightly abnormal plasma, the performance of the ACL method was quite satisfactory (CV 3-10%). However, in abnormal plasma (prolonged prothrombin times because of heparin or oral anticoagulants) the accuracy of the ACL method was poor. Nor could the instrument determine fibrinogen in clearly lipemic plasma. In plasma containing high concentrations of fibrin(ogen) degradation products (FDP), collected during thrombolytic therapy with streptokinase-containing drugs, the ACL method gave spuriously high values for fibrinogen concentration. We determined that this was mainly because of interference by intermediate FDP (fragment Y). Finally, we demonstrated that early FDP (fragment X) increased the ACL results for fibrinogen to the same extent as in the total clottable protein method and that late FDP (fragments D and E) affected the thrombin clotting time method, but not the ACL fibrinogen determination.
Macro-prostatic acid phosphatase in a patient's serum.
Authors: Schifferli J A , Roth P , Steiger G , Paccaud J P , Schmidt M
Published: January 2020

A patient without prostatic carcinoma had a high concentration of prostatic acid phosphatase (PAP; EC 3.1.3.2) in his serum. This PAP was bound to IgG ("macro-PAP"), and IgG autoantibodies against PAP were demonstrated in serum. The patient's IgG prolonged the biological half-life of radiolabeled PAP in rats, suggesting that the formation of IgG-PAP complexes was responsible for decreased PAP catabolism. Furthermore, macro-PAP was inactivated in serum more slowly than PAP. These factors accounted for the increases in the enzymatic activity and antigenic concentration of PAP measured in the patient's serum. Inappropriate therapy was prescribed on the basis of this laboratory result. The diagnosis of prostatic carcinoma requires clinical or histological evidence of malignant disease, and should not rely solely on PAP measurements.
Accumulation of indoxyl sulfate, an inhibitor of drug-binding, in uremic serum as demonstrated by internal-surface reversed-phase liquid chromatography.
Authors: Niwa T , Takeda N , Tatematsu A , Maeda K
Published: January 2020

We quantified indoxyl sulfate in uremic serum by using internal-surface reversed-phase high-performance liquid chromatography. Its concentrations were markedly increased in chronic hemodialysis patients, and were significantly but weakly correlated with the concentrations of creatinine and beta 2-microglobulin in these patients' serum, and with the duration of their hemodialysis treatment. Indoxyl sulfate could not be removed effectively by conventional hemodialysis because of its strong binding to serum albumin. Equilibrium dialysis demonstrated that indoxyl sulfate inhibited the binding of salicylate to albumin, and that 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid inhibited the binding of indoxyl sulfate to albumin. In conclusion, indoxyl sulfate was markedly accumulated in uremic serum, and inhibited drug binding.
Clinical usefulness of an enzymatic determination of total urinary polyamines, excluding cadaverine.
Authors: Mashige F , Tanaka N , Murakami T , Shimosaka H , Kamei S , Ohkubo A
Published: January 2020

In one widely used enzymatic method for urinary polyamines, the total concentrations of four polyamines--putrescine, spermidine, spermine, and cadaverine--are determined. We report here a simple enzymatic method for measuring the total concentrations of urinary polyamines except cadaverine. The coefficients of variation (CV) for within-run measurements by this method were 4.3% (means = 17.2 mumol/L) and 1.5% (means = 66.5 mumol/L), between-run CVs were 4.8% (means = 16.8 mumol/L) and 1.8% (means = 67.5 mumol/L). The central 95% normal reference interval was 12.3-29.1 mumol/g creatinine for men and 14.1-36.8 mumol/g creatinine for women. In some cases, physiological variations in urinary polyamine excretion were large, mainly because of variations in cadaverine excretion, even in health. Pathological changes in polyamine production in the body may therefore be more easily shown by the excretion of total polyamines excluding cadaverine than by that including cadaverine.
Enzymatic determination of sodium in serum.
Authors: Berry M N , Mazzachi R D , Pejakovic M , Peake M J
Published: January 2020

This is a kinetic assay for measuring serum Na+ concentration based on determination of Na+-dependent beta-galactosidase (EC 3.2.1.23) activity. The method, sufficiently sensitive to measure sub-millimolar concentrations of Na+, was modified by including a Na+-binding agent (cryptand) to provide a linear assay for serum Na+ concentrations between 110 and 160 mmol/L. The assay was developed with and evaluated in the Cobas Fara centrifugal analyzer (and has been used in other kinetic analyzers). Within-run and between-run CVs were less than 1%. The reaction rate for normal serum samples (0.20 delta A/min) is about 10-fold that of the reagent blank. Results correlated well with flame photometry. Interference from bilirubin, hemoglobin, lipemia, heparin, and other cations was negligible. The method offers a practical alternative to the use of ion-selective electrodes and flame photometry for measuring serum Na+ in high-throughput or "stat" biochemical analyzers.
Enzyme analysis of amniotic fluid for prenatal diagnosis of cystic fibrosis in high-risk pregnancies.
Authors: Peretz H , Chemke J , Usher S , Legum C , Graff E
Published: January 2020

We determined the activity concentrations of alkaline phosphatase (ALP), ALP isoenzymes, gamma-glutamyltransferase (GGT), and alpha-glucosidase (AGL) in 1200 unselected amniotic fluids and in amniotic fluids from 40 pregnancies at high risk for cystic fibrosis (CF). From the results we established the normal range and CF-predictive cutoff values for these enzymes in the second trimester of pregnancy. In all predicted normal pregnancies that went to term, normal children were born. Among the predicted affected pregnancies, 14 were terminated and two went to term, one resulting in a CF-affected child and the other in a healthy child. Evidence for CF was found in all 13 aborted fetuses examined (the parents of one refused to allow autopsy). We noted no differences in the amniotic fluid enzyme activities for the Arab and various Jewish ethnic groups living in Israel. We conclude that prenatal diagnosis of CF among the Israeli population at risk for CF is feasible by means of a reliable, fast, and economic test in the second trimester of pregnancy.
N-acetyl-beta-glucosaminidase isoenzymes in serum and urine of patients with diabetes mellitus.
Authors: Severini G , Aliberti L M , Di Girolamo M
Published: January 2020

The isoenzyme pattern of N-acetyl-beta-glucosaminidase (NAG) in serum and urine was studied in two groups of patients with diabetes mellitus and in 30 control subjects. Total NAG activity was significantly (P less than 0.001) increased in the serum and urine of the 20 diabetics with vascular complications, but was insignificantly increased in the 20 diabetics without vascular complications. Ion-exchange chromatography demonstrated the presence of two major isoenzymes of NAG, A and B. The proportion of isoenzyme A activity always exceeded that of isoenzyme B. The proportion of isoenzyme B in serum of diabetics was lower than in controls; the reverse was true for urine of diabetics. The NAG isoenzymes pattern may provide additional diagnostic information regarding diabetic status and complications of diabetes.
Specificity of the thiobarbituric acid reaction: its use in studies of lipid peroxidation.
Authors: Knight J A , Pieper R K , McClellan L
Published: January 2020

The thiobarbituric acid (TBA) reaction, quantified by colorimetry or fluorimetry, is the method most widely used for studying lipid peroxidation in both laboratory animals and in humans with disorders. However, concerns regarding its analytical specificity have often been expressed, because TBA reacts with a wide variety of chemical species to produce a pink to red color. In this study, we reacted TBA with various saturated and unsaturated aldehydes (both directly and in the presence of sucrose, fructose, and glucose), substituted pyrimidines, 2-deoxyribose, and N-acetylneuraminic acid. We also studied the TBA reaction with bilirubin, biliverdin, icteric serum, and serum containing hemolyzed erythrocytes, comparing the absorption spectra of these reaction products with that for malondialdehyde (MDA). The reaction products were also analyzed for MDA by high-performance liquid chromatography (HPLC). Although the TBA reaction with some of these compounds may not be important in biological studies, others could lead to misinterpretations of increased lipid peroxidation. Use of HPLC to quantify MDA is recommended because of its high analytical sensitivity and specificity, especially in the study of lipid peroxidation in human subjects.
Clinical performance of a parathyrin immunoassay with dynamically determined reference values.
Authors: Lepage R , D'Amour P , Boucher A , Hamel L , Demontigny C , Labelle F
Published: January 2020

We compared the clinical performance of a carboxyl-terminal radioimmunoassay for human parathyroid hormone (iPTH), using either a dynamic reference interval (95% confidence limits of serum iPTH concentrations observed in 11 normal individuals during intravenous infusions of Na2EDTA and CaCl2) or a gaussian (2 SD) reference interval derived from 233 normocalcemic individuals. The 2 SD ranges were 3.5 to 9.8 pmol/L for serum iPTH and 2.19 to 2.53 mmol/L for total calcium. The iPTH dynamic interval was lower for calcium concentrations greater than 2.50 mmol/L; it was higher, wider, and continued to increase for calcium values less than or equal to 2.25 mmol/L. Use of the dynamic reference interval increased the clinical sensitivity of our assay from 81% and 61% to 100%, respectively, in primary hyperparathyroidism (n = 47) and hypoparathyroidism (n = 18). Test specificity was maintained at 100% in hypocalcemic disorders but fell to 93% (62/67) in hypercalcemic disorders. Overall, use of the dynamic reference interval improved the assay performance.
Activities of creatine kinase and its isoenzymes in serum in various skeletal muscle disorders.
Authors: Arenas J , Diaz V , Liras G , Gutierrez E , Santos I , Martinez A , Culebras J M
Published: January 2020

We studied possible correlations between anatomopathological and clinical features and the values for total creatine kinase (CK; EC 2.7.3.2) and its isoenzymes, including the proportion of CK-MB, in a population displaying several neuromuscular pathologies. Although we observed no specific isoenzyme pattern associated with the different myopathies, we found isoenzyme analysis useful in studying the histopathological evolution of illness. We also considered whether the pathology was regenerative or nonregenerative, and what type of fiber (I or II) was involved. High CK-MB percentages (greater than 6%) were associated with regenerative and type I fiber myopathies, with regenerative type tissues being the principal factor associated with an increasing proportion of CK-MB. Studying the changes in CK-MB percentage in serum appears to be useful in discriminating neuromuscular from myocardial pathologies.
Ferrochelatase activity in human lymphocytes, as quantified by a new high-performance liquid-chromatographic method.
Authors: Rossi E , Costin K A , Garcia-Webb P
Published: January 2020

We describe a new rapid, sensitive high-performance liquid-chromatographic (HPLC) method for determining ferrochelatase (EC 4.99.1.1) activity in lymphocytes. Zinc and mesoporphyrin are incubated aerobically with sonicated lymphocytes and the zinc mesoporphyrin formed is extracted with dimethyl sulfoxide-methanol-EDTA for quantification by HPLC. Incubation conditions, including the concentration of the palmitic acid activator, were optimized. The Michaelis constant (Km) was 2.1 mumol/L for mesoporphyrin, 22.2 mumol/L for zinc. The mean ferrochelatase activity (expressed as zinc mesoporphyrin formed per hour per milligram of lymphocyte protein) for a reference population was 3.25 (SD 0.43) nmol.h-1.mg-1. For three patients with erythrohepatic protoporphyria (EHP), activities were 1.11, 1.30, and 1.35. Neutrophils contain negligible ferrochelatase activity.
Exponential function for calculating saturable enzyme kinetics.
Authors: Keller F , Emde C , Schwarz A
Published: January 2020

Enzyme kinetics are usually described by the Michaelis-Menten equation, where the time-dependent decrease of substrate (-dS/dt) is a hyperbolic function of maximal velocity (Vmax), Michaelis constant (Km), and amount of substrate (S). Because the Michaelis-Menten function in its most general meaning requires an assumption of steady-state, it is less curvilinear than true enzyme kinetics. A saturation-type exponential function is more curvilinear than the hyperbolic function and more closely approximates enzyme kinetics: -dS/dt = Vmax [1 - exp(-S/Km)]. The mathematical representation of enzyme kinetics can be further improved by introducing a deceleration term (Vdec), to make the assumption of a steady state unnecessary. For the action of chymotrypsin on N-acetyltyrosylethylester, the Michaelis-Menten equation yields the following: Vmax = 3.74 mumol/min and Km = 833 mumol. According to decelerated enzyme kinetics, the values Vmax = 4.80 mumol/min, Vdec = 0.0118 mumol/min, and the association constant (Ka) = 0.00111/mumol are more nearly accurate for this reaction (where 1/Ka = 901 mumol approximately Km).
Liquid-chromatographic quantification compared with gas-chromatographic-mass-spectrometric determination of verapamil and norverapamil in plasma.
Authors: Hynning P A , Anderson P , Bondesson U , Boréus L O
Published: January 2020

A high-performance liquid chromatographic (HPLC) method for determining verapamil and norverapamil in plasma is presented and compared with gas chromatography/mass spectrometry (GC-MS). The plasma samples were extracted at alkaline pH with hexane containing 2-butanol (20 mL/L) and then back-extracted into phosphate buffer (0.1 mol/L, pH 3.0). For chromatography we used a reversed-phase column (Supelcosil LC-18 DB) with a mobile phase of the phosphate buffer and acetonitrile (70/30 by vol). Fluorescence detection was used (excitation at 203 nm, emission at 320 nm). Overall analytical recovery was 85%. Standard curves were linear from 1 to 1000 micrograms/L. The detection limit was 1 microgram/L. The assays are accurate and precise. We found no interferences by those substances tested. Results by HPLC and GC-MS agreed well (r = 0.99) for both verapamil and norverapamil determinations.
Fully automated liquid-chromatographic determination of amino acids.
Authors: van Eijk H M , van der Heijden M A , van Berlo C L , Soeters P B
Published: January 2020

This inexpensive method for fully automated amino acid analysis combines the advantages of automated precolumn derivatization with o-phthaldialdehyde and favorable analytical conditions to separate and quantify 30 amino acids found in normal plasma. The system can run unattended for almost four days, during which the data are processed automatically by a personal computer and a maximum of 76 samples and 19 standards can be processed (cycle time per analysis: 55 min). Only 1 microL of deproteinized plasma is required per analysis. Coefficients of variation for retention times and areas measured for all relevant amino acids are less than 1% and 3%, respectively. The system described is well suited for quick, sensitive operation in daily practice.
Influence of strenuous exercise on albumin excretion.
Authors: Krämer B K , Kernz M , Ress K M , Pfohl M , Müller G A , Schmülling R M , Risler T
Published: January 2020

Renal albumin excretion rate was 7.3 mg/24 h (SEM 0.5, range 0.6-21.0) in 66 healthy subjects. This rate increased markedly during and shortly after strenuous exercise on a bicycle ergometer (before: 5.5 +/- 0.6 micrograms/min; during and just after: 16.9 +/- 2.2 micrograms/min; P less than 0.001; n = 30). However, albumin excretion/24 h was not significantly higher during 24 h with a period of strenuous exercise than during 24 h without such exercise (10.3 +/- 0.9 mg/24 h vs 8.5 +/- 0.7 mg/24 h).
Applicability of the Ektachem 400 analyzer for assaying analytes in miscellaneous body fluids.
Authors: Georgewill D A , Graham G A , Schoen I
Published: January 2020

The Ektachem analyzer, a slide-film chemistry technology, demonstrated applicability to non-serum, non-urine stimulated and actual clinical specimens having a wide range of protein concentration and pH. The simulated specimens studied had pH and protein that ranged from 2 to 9 and 0 to 88 g/L, respectively. Actual patients' specimens studied, which had protein concentrations ranging from 0.1 to 60 g/L, included peritoneal fluid, vitreous fluid, synovial fluid, pericardial fluid, and cerebrospinal fluid. The analytes studied included glucose, urea nitrogen, uric acid, creatinine, calcium, phosphorus, sodium, potassium, chloride, and carbon dioxide.
Determination of manganese in biological materials by electrothermal atomic absorption spectrometry: a review.
Authors: Baruthio F , Guillard O , Arnaud J , Pierre F , Zawislak R
Published: January 2020

The great diversity of methods for measuring manganese in biological materials (serum, plasma, whole blood, urine, spinal fluid, and hair) reflects the difficulty in measuring extremely small quantities of this element. Detailed examination of these methods demonstrates that the one most used is flameless atomic absorption spectrometry. In this review we report the different instrument settings for wavelength, slit width, protection gases, graphite furnaces, type of background correction, amounts measured, and thermal programs. We give detailed recommendations by various authors for collecting samples. A thorough description of the preliminary steps and the handling of the specimen samples is also included: direct determination with or without dilution, addition of a matrix modifier or determination after ashing, with or without chelation-extraction steps. The preparation of the standards, procedures used, analytical criteria (accuracy, precision, specificity, detection limit, linearity), problems (interferences, matrix effects), and reference values and their physiological variations are also described. We give a consensus of recommendations concerning the choice of a method.
"Sandwich"-type immunoassay of carcinoembryonic antigen in patients receiving murine monoclonal antibodies for diagnosis and therapy.
Authors: Primus F J , Kelley E A , Hansen H J , Goldenberg D M
Published: January 2020

Measurements of carcinoembryonic antigen (CEA) in blood increased dramatically in some patients who were receiving injections of monoclonal antibody. CEA titers were measured with a monoclonal antibody-based double-determinant enzyme immunoassay in which untreated plasma specimens were diluted with an equal volume of buffer containing mouse serum. Increasing CEA titers were accompanied by the appearance and coincident increase in titers of human antibody against mouse Ig (HAMA). Adsorption of these sera with solid-phase anti-human IgG or Protein A restored antigen titers to pretreatment values; evidently the serum factor eliciting false-positive CEA titers was most probably HAMA. Neither addition of undiluted mouse serum to the assay mixture nor pretreatment by heating plasma specimens to 70 degrees C effectively abolished HAMA interference. By contrast, protein precipitation with polyethylene glycol (130 g/L) or heating plasma samples to 90 degrees C eliminated false-positive titers caused by HAMA, but did not reduce authentic CEA titers.
Preliminary tests for drugs of abuse.
Authors: Sunshine I
Published: January 2020

A drug-testing program must be designed by the client in consultation with the laboratory. The test procedures selected for the analytes in question depend on the defined "cutoff" concentrations, equipment available, and turnaround time. Preliminary tests are needed to separate the large number of negatives from presumptive positives, which then have to be confirmed. Immunoassays done with random-access analyzers are the procedures of choice. In clinical situations, thin-layer chromatographic procedures may be favored. The attributes and liabilities of the various procedures are presented as guides to the selection of a suitable procedure for a particular client.
What is the cause of benign transient hyperphosphatasemia? A study of 35 cases.
Authors: Crofton P M
Published: January 2020

In a study of 35 children with benign transient hyperphosphatasemia, I found a marked seasonal clustering of cases after the summer months. Furthermore, plasma 25-hydroxyvitamin D concentrations were almost twice those of controls matched for age and time of year. Many children had evidence of weight loss and one had idiopathic hypercalcemia of infancy. Activities both of liver and bone isoenzymes of alkaline phosphatase (EC 3.1.3.1) in plasma were increased. The liver and (to a lesser extent) bone isoenzymes had enhanced electrophoretic mobility, and both showed increased binding to wheat-germ lectin by affinity electrophoresis. For the liver (and probably also the bone) isoenzyme, these changes were due to an increased content of sialic acid. A possible etiology for the condition is proposed involving (a) increased synthesis of alkaline phosphatase, mediated by vitamin D metabolites, and (b) decreased hepatic clearance caused by the high sialic acid content and exacerbated in some cases by the effects of some drugs on the liver.
Rapid evolution in the immunochemical findings of a gamma heavy chain disease.
Authors: Pontet F , Gué X , Dosquet C , Caen J , Rousselet F
Published: January 2020

We noted the following major immunochemical changes in the final course of a gamma heavy-chain disease associated with a myelomonocytic leukemia: an important oligoclonal increase of IgG1/kappa, during sepsis development, whereas the lambda molecules decreased and IgG2 and IgG3 completely disappeared in a one-month interval. Initial concentrations of IgG4 were stable during that period, and gamma 1 heavy chains were slightly increased. This is a very unusual observation of the successive immunochemical events terminating a gamma heavy-chain disease.
Trace elements in human clinical specimens: evaluation of literature data to identify reference values.
Authors: Iyengar V , Woittiez J
Published: January 2020

Reference values are proposed for the concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Pb, Se, and Zn in whole blood, blood serum, urine, milk, liver, and hair from adult human subjects. For F, I, and Ni, it was not possible to evaluate reference intervals for all the specimens mentioned above. For several elements, including Al, B, Br, Cs, Li, Rb, U, and V, the present status of the literature does not provide an adequate basis for formulating baseline concentrations; therefore, results from selected investigations are listed for information only. For elements such as Cu, Fe, and Zn, which are known to be homeostatically controlled, the concentrations in whole blood and blood serum follow a gaussian-like frequency distribution, and we could consider both median and mean values for evaluation. On the other hand, elements whose concentrations in tissues and body fluids are influenced by dietary availability (e.g., As and Se) or environmental factors (e.g., Cd, Hg, and Pb) show wide scatter. In these cases, the median appeared to be a better indicator of the central tendency than the mean, when different populations are involved. These points are illustrated.
Preparation of monoclonal antibodies reactive with beta-1,2-linked oligomannosyl residues in the phosphomannan-protein complex of Candida albicans NIH B-792 strain.
Authors: Tojo M , Shibata N , Kobayashi M , Mikami T , Suzuki M , Suzuki S
Published: January 2020

Hybridomas obtained by fusing the spleen cells of BALB/c female mice hyperimmunized with heat-killed yeast-form cells of Candida albicans NIH B-792 strain and a mouse myeloma cell line, P3X63Ag8.653, produced antibodies to beta-1,2-linked oligomannosyl residues in the phosphomannan-protein complex of the parent cells. Most of these monoclonal antibodies were IgM, but about 10% of the hybridomas produced IgG1 immunoglobulins. Ascites fluid from BALB/c mice inoculated with an IgG1-producing hybridoma showed different precipitability with the phosphomannan-protein complexes of three representative C. albicans strains, with NIH B-792 (serotype B) greater than NIH A-207 (serotype A) greater than J-1012 (serotype A, formerly serotype C). In contrast, a rabbit polyclonal antiserum to C. albicans NIH B-792 cells was unable to distinguish these same complexes. This ascites fluid agglutinated the heat-killed cells of three Candida strains, but not those of three others or of Torulopsis glabrata IFO 0622. The other ascites fluids, containing antibodies of the IgM class, agglutinated cells from three C. albicans strains and also C. tropicalis IFO 0587 cells.
Cerebrospinal fluid IgG and IgM indexes as indicators of active neurosyphilis.
Authors: Hische E A , Tutuarima J A , Wolters E C , van Trotsenburg L , van Eyk R V , Bos J D , Albert A , van der Helm H J
Published: January 2020

Serological and non-serological tests were performed in matched samples of cerebrospinal fluid and serum from 236 syphilitic patients. An increased IgG or IgM index, or both, was found about 70 times more often in symptomatic neurosyphilis than in latent syphilis without involvement of the central nervous system. An increased Ig index, together with a cell count greater than 5/microL, was only found in symptomatic neurosyphilis. Although the numbers of data are small, we conclude that the IgG and IgM indexes are valuable tests in the diagnosis of syphilitic involvement of the central nervous system.
Plasma and urinary taurine in epilepsy.
Authors: Collins B W , Goodman H O , Swanton C H , Remy C N
Published: January 2020

A previous study showed that significantly less taurine is excreted in the urine by epileptics than by control subjects. The difference is ascribed to genetic variation in taurine transport governed by a pair of codominant polymorphic alleles. The present study of plasma taurine concentrations and urinary taurine output confirms previous findings among epileptics and provides evidence that some anticonvulsant medications may affect taurine transport. The posited codominant alleles represent the first single-locus component in the polygenic complexes creating susceptibility to seizures and epitomizes the small additive effects classically attributed to such genes.
Rapid equilibrium radioimmunoassay for the amino-terminal propeptide of human type III procollagen.
Authors: Risteli J , Niemi S , Trivedi P , Mäentausta O , Mowat A P , Risteli L
Published: January 2020

This is an equilibrium-type radioimmunoassay for the amino-terminal propeptide of type III procollagen (PIIINP), which overcomes the problem of nonparallelism between the standard and human serum samples encountered with earlier assays. Proper selection of antiserum and reaction conditions diminishes interference from degradation products of the propeptide in serum. Because a rapid solid-phase-bound second-antibody step is included, the assay takes only 3 h. The intra-assay and the interassay CVs are both about 5%. In infants and children the concentration of PIIINP in serum closely parallels the growth-velocity curve. For 88 presumably healthy adults, the PIIINP concentration was 1.7-4.2 micrograms/L, about a third that measured with the previously available commercial assay. This is because of lack of inhibition by small Col 1 domain-related degradation products.
A high-performance liquid-chromatographic method for routine simultaneous determination of nicotine and cotinine in plasma.
Authors: Hariharan M , VanNoord T , Greden J F
Published: January 2020

We describe a rapid, sensitive method for the routine simultaneous determination of nicotine and cotinine in 1 mL of plasma. Extraction in 10-mL screw-capped Teflon tubes with methylene chloride after deproteinization with trichloroacetic acid eliminated emulsion formation. The extract, after evaporation and reconstitution in 30 microL of mobile phase, is injected into a reversed-phase C-18 ion-pair column of an isocratic high-performance liquid-chromatographic unit. Absorbance is monitored at 256 nm. The mobile phase is a citrate-phosphate (30 mmol each per liter) buffer mixture containing 50 mL of acetonitrile and 1 mmol of sodium heptanesulfonate per liter. 2-Phenylimidazole is the internal standard. The detection limit is 1 microgram/L for nicotine and 3 micrograms/L for cotinine. The standard curve is linear from 0 to 700 micrograms/L for both compounds. The average CV for nicotine in the concentration range 0-100 micrograms/L is 6.5%, and that for cotinine in the concentration range 50-700 micrograms/L is 4%.
Oligoclonal bands in cerebrospinal fluids: significance of corresponding bands in serum for diagnosis of multiple sclerosis.
Authors: Davenport R D , Keren D F
Published: January 2020

Controversy exists regarding the definition of oligoclonal bands in cerebrospinal fluid (CSF) and whether CSF bands with corresponding bands in the serum should be disregarded in the interpretation. Much of this controversy results from not distinguishing between the sensitivities of different techniques used for these studies. Because the combination isoelectric focusing/silver staining is more sensitive than agarose gel electrophoresis/Coomassie Blue staining for detecting weak bands, one would expect to find weak oligoclonal bands in the serum more frequently with the former technique than the latter. Yet, most clinical laboratories use agarose gel electrophoresis for this assay. To investigate the clinical relevance of CSF oligoclonal bands as compared with corresponding bands for serum by electrophoresis on agarose gel, we retrospectively reviewed paired CSF and serum electrophoretograms of 104 patients. We determined that the specificity of the oligoclonal-band test for diagnosis of multiple sclerosis was significantly enhanced by running paired CSF and serum specimens when CSF bands with corresponding serum bands were discounted.
Erroneous results with routine laboratory testing for immunoglobulins due to interference from circulating immune complexes in a case of hyperviscosity syndrome associated with autoimmune disease.
Authors: Levinson S S , Perry M , Goldman J , Nathan L E
Published: January 2020

A patient with the hyperviscosity syndrome exhibited very high concentrations of intermediate to small circulating immune complexes (CIC), involving 40-50% of the IgG present, with IgG rheumatoid factor activity. We demonstrate that precipitation of CIC by polyethylene glycol in the reaction mixture caused interference with nephelometric methods for measuring IgM and IgA, and that failure of immunoglobulins to migrate, owing to molecular interactions, caused interference with radial immunodiffusion methods. Semiquantitative values for immunoglobulins were difficult to interpret on immunoelectrophoresis. As a result, IgM and IgA could only be quantitatively estimated by an end-point nephelometric approach that included a serum blank. Immunoelectrophoresis indicated that a large proportion of the immunoglobulins behaved as aggregates. Immunofixation electrophoresis did not reveal the presence of aggregates. The polyethylene glycol-IgG test provided an accurate assessment of the CIC concentration; the Raji cell and C1q-binding assays did not. Evidently, special techniques may be necessary for accurate determination of immunoglobulin concentrations when CIC concentrations are very high.
Therapeutic drug monitoring of tricyclic antidepressants.
Authors: Preskorn S H , Dorey R C , Jerkovich G S
Published: January 2020

The traditional dose-response method of medication adjustment depends on several assumptions that are not met in the case of tricyclic antidepressants (TCAs), which makes therapeutic drug monitoring (TDM) particularly useful with these drugs. TDM can facilitate treatment by providing objective guidelines for dose adjustment. It provides a means of assessing compliance, ensuring an effective concentration, and avoiding toxicity. The latter is an often-overlooked benefit of therapeutic monitoring of TCAs and yet is just as important as improving response. The cardiac and central nervous system toxicity of TCAs is concentration-dependent and potentially life-threatening. Such toxicity will predictably occur in up to 5% of patients on standard antidepressant doses of TCAs when TDM is not used to rationally adjust the dose. Without TDM, such toxicity is difficult to detect early. A cost/benefit analysis supports the cost effectiveness of TDM as a standard part of TCA chemotherapy when doses in the 100-300 ng/day range are used.