bluuebunny/crossref_metadata_2025 huggingface dataset:
Endogenous digoxin-like immunoreactive factors: impact on digoxin measurements and potential physiological implications.
Authors: Valdes R
Published: January 2020

Various laboratories have reported endogenous digoxin-like immunoreactive factor(s) (DLIF) in blood from patients in renal failure or liver failure, from newborn infants, and from third-trimester pregnant women. Similar immunoreactivity has been detected in amniotic fluid, in cord blood, and in urine and serum from normal subjects. The factor(s) giving rise to this immunoreactivity cross react with antibodies used in many currently available immunoassays for digoxin, sometimes causing apparent digoxin concentrations exceeding the therapeutic range obtained for exogenous digoxin, with consequent errors in measurement and in subsequent clinical interpretation of digoxin results. Here, I summarize findings in our laboratory and those of others. DLIF evidently exist in three states in serum: tightly protein-bound, weakly protein-bound, and unbound (free). In normal subjects, greater than 90% of the total DLIF in serum is tightly but reversibly bound to serum proteins and is not readily detectable by direct measurement of digoxin in serum with conventional immunoassays. However, there seems to be a redistribution of the more weakly bound and unbound components in patients with renal failure, pregnant women, and newborns. The increased values detected in these groups are ascribable to increased amounts of weakly bound and unbound DLIF rather than to increased total DLIF. Carrier proteins may play a prominent role in the transport of these factors in blood. I discuss the potential physiological and pharmacological implications of detecting endogenous immunoreactive factors that cross react with antibodies to drugs.
Influence of oral contraceptives and pregnancy on constituents of the kallikrein-kininogen system in plasma.
Authors: Adam A , Albert A , Boulanger J , Genot D , Demoulin A , Damas J
Published: January 2020

We measured kininogens of low and high molecular mass along with prokallikrein activity in plasma of women with a normal menstrual cycle. We observed no difference between results for the follicular and luteal phases. We assayed the same constituents in women who were taking oral contraceptives (combined estroprogestative) and found that activity of prokallikrein and concentrations of low- and high-molecular-mass kininogens were significantly increased. Lastly, we studied the components of the kallikrein-kininogen system during pregnancy. We also observed a marked increase in their concentrations in plasma, despite a decrease in total proteins. Specifically, prokallikrein and kininogens increase continuously with gestational age, reaching their maxima around the eighth month of pregnancy. At that time, more than 50% of observed results fall outside the normal reference interval. Our observations are even more striking when prokallikrein and kininogens are expressed in units per gram of total proteins, to account for the hemodilution. After delivery, the concentrations of prokallikrein and low- and high-molecular-mass kininogens decline promptly, returning to normal within three days.
Heterogeneous enzyme immunoassay with electrochemical detection: competitive and "sandwich"-type immunoassays.
Authors: Wehmeyer K R , Halsall H B , Heineman W R
Published: January 2020

In these competitive and "sandwich"-type heterogeneous enzyme immunoassays, based on liquid chromatography with electrochemical detection, rabbit immunoglobulin G is used as a model compound. Alkaline phosphatase (EC 3.1.3.1), the labeling enzyme, catalyzes conversion of phenyl phosphate to phenol. After separation on an octyldecylsilane column, the enzyme-generated phenol is detected in a thin-layer cell at a carbon-paste working electrode. The detection limit for phenol is 5.0 nmol/L. The electrode response varies linearly with concentration over a range of three orders of magnitude. For the sandwich-type assay procedure the detection limit is 10 ng/L; the linearity ranges over four orders of magnitude. The detection limit of the competitive immunoassay is 5 micrograms/L. The dynamic range spans two orders of magnitude.
Use of protein-based standards in automated colorimetric determinations of fructosamine in serum.
Authors: Baker J R , Metcalf P A , Johnson R N , Newman D , Rietz P
Published: January 2020

We have developed an automated colorimetric assay for glycated serum proteins (or fructosamines), measuring the reducing activity of serum in alkaline solution (pH 10.35) at 37 degrees C. The calibrants were prepared from a synthetic fructosamine (1-deoxy-1-morpholinofructose), although secondary standards of glycated bovine albumin were more robust in routine application. Interference was appreciable only with icteric specimens (bilirubin greater than 60 mumol/L), and between-batch imprecision (CV) was less than 2%. The range of fructosamine concentrations measured in 502 healthy (nondiabetic) blood donors was 1.87-2.87 mmol/L. There were no significant (p greater than 0.05) age- or sex-related differences in this population sample. Fructosamine accurately reflected blood glucose control as evidenced by the significant correlation with glucose concentrations in fasting plasma (r = 0.82, p less than 0.001) and with glycated hemoglobin (HbA1c) (r = 0.87, p less than 0.01) in 115 patients with type 2 (non-insulin-dependent) diabetes mellitus. The test is simple and rapid to perform (75 samples per hour) and provides an alternative to HbA1c determinations for monitoring blood glucose control and assessing the effects of changes in diabetes management.
Bedside micro-method for measuring effective hepatic blood flow, with use of first-order galactose clearance pharmacokinetics.
Authors: Rypins E B , Sankary H , Wynn M J
Published: January 2020

Data from first-order galactose clearance were used to estimate "effective" hepatic blood flow in normal subjects and in patients with hepatic diseases. Galactose clearance was determined by infusing galactose intravenously at a constant rate and measuring its resulting steady-state concentration in blood. The infusion rate must not exceed the maximum rate of galactose clearance by the liver, the "galactose elimination capacity." With this constraint and within the physiological and pathophysiological limits of hepatic blood flow, a constant infusion at 50 mg/min results in steady-state concentrations ranging from 20 to 200 mg/L. To measure galactose within this range, we modified a YSI Model 23A glucose analyzer and, using an immobilized galactose oxidase (EC 1.1.3.9)/hydrogen peroxide electrode system, accurately measured galactose in water and blood. The galactose metabolic clearance rate was calculated for six normal rats and for a normal and a cirrhotic human subject. The speed of the analysis (40 s), the small sample required (25 microL), and the suitability of fresh whole blood as the sample make the method ideal for measuring hepatic blood flow in small laboratory animals as well as for determining at bedside the effective hepatic blood flow in humans.
Use of the serum copper/zinc ratio in the differential diagnosis of ovarian malignancy.
Authors: Lightman A , Brandes J M , Binur N , Drugan A , Zinder O
Published: January 2020

We measured copper and zinc in serum (n = 82) and tumor tissue (n = 41) from women with a palpable pelvic mass, admitted for suspected ovarian tumor. In serum, copper was increased and zinc decreased in the group (n = 40) subsequently proven to have a malignant ovarian tumor. The mean copper/zinc ratio in this group was 2.30 (SD 0.41), significantly (p less than 0.001) higher than for the benign group (n = 42), 1.43 (SD 0.22). In tumor tissue the concentrations of copper and zinc followed the same pattern, the copper/zinc ratio being significantly (p less than 0.001) higher in the malignant (0.158, SD 0.065) tumors than in the benign tissue (0.093, SD 0.04). We conclude that the Cu/Zn ratio in serum reliably (specifically) indicates the presence of advanced ovarian malignant tumor. The decreased concentrations of zinc and the increased concentrations of copper in serum do not seem to result from a shift of zinc into or release of copper out of the malignant tumor tissue.
Plasma cholinesterase phenotyping with use of visible-region spectrophotometry.
Authors: Abernethy M H , George P M , Herron J L , Evans R T
Published: January 2020

A method that overcomes the difficulties of the 240-nm benzoylcholine method for phenotyping plasma cholinesterases has been developed. After a timed reaction, under the same reaction conditions as in the classic procedure, choline is detected at 500 nm by use of choline oxidase coupled with the peroxidase/phenol/aminoantipyrine system. Cholinesterase activity measurements, calibrated by use of choline iodide as standard, are linearly related to results obtained with propionylthiocholine as substrate at 25 degrees C (y = 0.14x + 0.17, n = 30, r = 0.98). Results of differential inhibition with dibucaine and fluoride are virtually identical with those obtained by the ultraviolet method (y = 0.97x + 4.3, r = 0.995, and y = 0.93x - 0.5, r = 0.987, respectively) and give the same classification of homo- and heterozygotes for the usual, atypical, and fluoride-resistant variants. The new method has substantial advantages in that it eliminates the difficulties associated with measuring small changes in high absorbances at a suboptimal wavelength on a steep portion of the absorption curve.
Liquid-chromatographic assay of cefamandole in serum, urine, and dialysis fluid.
Authors: Bliss M , Mayersohn M
Published: January 2020

We describe a "high-performance" liquid-chromatographic assay for quantifying cefamandole in biological fluids from patients with renal impairment. Serum samples are deproteinized with acetonitrile, then extracted with dichloromethane; dialysis-fluid samples are injected directly; urine samples are diluted appropriately before injection onto the reversed-phase column. The mobile phase is a methanol/aqueous solution (31/69 by vol) containing 500 microL of phosphoric acid, 20 mmol of sodium sulfate, and 200 microL of triethylamine per liter, the mixture being adjusted to pH 6.0 with NaOH. Retention time for cefamandole is 12 min. Its peak is well resolved in highly contaminated samples from renally impaired subjects. The assay's selectivity, reproducibility (within-day and between-day CVs less than 8% in all three sample fluids), and sensitivity--0.5 mg/L in serum, 1.0 mg/L in dialysis fluid, and 5.0 mg/L in urine--make it applicable to pharmacokinetic studies.
A specific antibody to vasopressin in a man with concomitant resistance to treatment with Pitressin.
Authors: Bichet D G , Kortas C , Manzini C , Barjon J N
Published: January 2020

A 26-year-old man with complete neurogenic diabetes insipidus since age nine was initially treated with vasopressin (Pitressin Tannate in oil). At age 13, its dosages were progressively increased to control the patient's polyuria; minor allergic symptoms occurred after every such treatment. We incubated serial dilutions of the patient's plasma with 125I-labeled arginine-vasopressin and obtained a 50% specific binding for the plasma at a final dilution of 625-fold. Cross-reactivity studies showed that lysine-vasopressin was better recognized by the antibody than arginine-vasopressin. These results were attributed to large concentrations of lysine-vasopressin (pork vasopressin) in the Pitressin.
Standardizing clinical laboratory data for the development of transferable computer-based diagnostic programs.
Authors: Strike P W , Michaeloudis A , Green A J
Published: January 2020

The existence of systematic differences between test results obtained at different laboratories can compromise the development of generally accessible reference databases for interpretive pathology. We review approaches to the elimination of inter-laboratory bias from pathology test results through the use of standard unit transformations. A general transform procedure is described that will permit laboratories serving a common population to make use of reference data, decision rules, and computer-based interpretive programs developed around a larger clinical database than each of these test centers could amass for themselves.
One-step immunoassays for free (unbound) hormones: the effect of tracer binding by serum proteins.
Authors: Geiseler D , Chodha P , Ekins R
Published: January 2020

In binding assays for determination of free (non-protein-bound) hormones in serum or plasma, the influence of the measuring system on the original analyte concentration in the sample must be considered. In one- or single-step free-hormone immunoassays, the labeled analyte or analog-tracer not only is bound to the antibody, it also is bound, to some extent, to serum proteins. The dependence of the assay response on two unknown variables--the concentration of free analyte and the binding potential of serum for the tracer--introduces a bias between the actual (original) and measured hormone concentrations. The significance of this protein effect is described by mathematical modeling of the analyte-protein distribution in the assay system. The theoretical consideration is validated by a clearly defined one-step assay system for measurement of free-thyroxin concentration, with a labeled thyroxin-immunoglobulin conjugate used as tracer.
Simultaneous determination of cerebrospinal fluid oligoclonal bands and the "gamma-protein index" by agarose electrophoresis and densitometry.
Authors: French C A , Tracy R P , Rudick R A , Kraemer A M , Arvan D A
Published: January 2020

Oligoclonal bands were identified in electropherograms of cerebrospinal fluid, and the "gamma-protein index" was concurrently calculated from the same strip. For the index, an upper limit of normal of 0.66 was established. We compared results with the clinical diagnosis in 69 patients with multiple sclerosis and 48 control patients with other diseases. Sensitivity, specificity, and positive predictive values of 73%, 96%, and 96%, respectively, were obtained from the index. An abnormal index and the presence of oligoclonal bands combined increased the positive predictive value to 100%. This approach may allow adequate qualitative and quantitative assessment of gamma-globulin abnormalities in cerebrospinal fluid after a single laboratory procedure.
Implementation of a screening program for diagnosing open neural tube defects: selection, evaluation, and utilization of alpha-fetoprotein methodology.
Authors: Christensen R L , Rea M R , Kessler G , Crane J P , Valdes R
Published: January 2020

We evaluated and compared three different commercial kit immunoassays for alpha-fetoprotein (AFP) before we implemented our neural tube defect screening program. Each kit can be used with either serum or amniotic fluid. Analytical recovery ranges for AFP reference sera within each kit's standard curve limits (in kilo-int. units/L) were 97-108% (7.5-180) for the Kallestad kit, 77-101% (21.8-436) for Amersham, and 92-100% (0-177) for Hybritech. CVs, within each manufacturer's standard-curve limits, for combined intra-assay (amniotic fluid pools) and inter-assay (kit serum controls) averaged 3.6-7.3% (Kallestad), 2.4-9.3% (Amersham (y) kit results showed a correlation of r = 0.97, y = 1.05x + 5.5 kilo-int. units per liter of maternal serum (n = 66; range, 2.0-98.5). Gestational age did not influence these assay correlations. The Kallestad AFP assay demonstrated a maternal serum positivity rate of 2.9% at greater than or equal to 2.5 (n = 655) and 8.9% at less than 0.5 (n = 423) multiples of the median. All kits performed well analytically.
Relationships of cyclosporine concentrations in serum, whole blood, and bile after renal and hepatic transplantation.
Authors: Vine W , Flye M W , Jatlow P
Published: January 2020

"Trough" (minimum inter-dose) cyclosporine concentrations were measured by liquid chromatography in samples of serum and whole blood or bile obtained from renal- and hepatic-transplant patients. Overall, concentrations in whole blood correlated poorly with concentrations in concurrently obtained serum. The poor correlation also held for individual patients over time. The degree of variability observed for individuals is especially disconcerting. Although cyclosporine measurements in whole blood may mitigate time- and temperature-dependent changes in the drug's distribution after collection, concentrations in serum separated after distribution are less dependent on the cellular mass in blood, and may better reflect the amount of drug available to receptor sites. This consideration may be particularly important in the postoperative period, when fluctuations in the cellular mass of blood are frequent. Concentrations of cyclosporine were also determined in concurrently collected bile and serum samples after liver transplantation. Concentrations of unchanged drug in bile were variably higher than those in serum. Bile/serum concentration ratios ranged from 65/1 to 4.6/1. It is postulated that bile/blood concentration ratios may reflect liver function.
Use of monoclonal and polyclonal antibodies to detect prostatic acid phosphatase by immunoblotting.
Authors: Patel P C , Aubin L , Côte J
Published: January 2020

We investigated two techniques of immunoblotting--the Western blot and the dot blot--for use in detecting prostatic acid phosphatase (PAP, EC 3.1.3.2). We used polyclonal antisera to human PAP, produced in rabbits by hyperimmunization with purified PAP, and PAP-specific monoclonal antibodies in the immunoenzymatic protocols. We conclude that PAP can be readily detected by Western blots with use of polyclonal antisera, but not with monoclonal antibodies. On the other hand, using a dot blot assay, we could easily detect PAP with both polyclonal and monoclonal antibodies.
Gas-liquid chromatography of phencyclidine in serum, with nitrogen-phosphorus detection.
Authors: Werner M , Hertzman M , Pauley C J
Published: January 2020

We developed a two-step assay of phencyclidine (PCP), in which 2.5 mL of serum is adsorbed onto a disposable solid-phase extraction column and the eluted drug is determined by gas chromatography with nitrogen-phosphorus detection. Methapyriline is the internal standard. The detection limit of this technique is 0.5 microgram/L and the linear range exceeds 200 micrograms/L. Precision (CV) ranges from 30 to 10% with increasing concentration. No interferences were encountered in more than 400 clinical samples. The assay permits serial observation of low concentrations of the drug in serum for pharmacokinetic study and for quantitative clinical correlation with the Brief Psychiatric Rating Scale.
Simultaneous gas-chromatographic determination of free and acetyl-conjugated polyamines in urine.
Authors: van den Berg G A , Muskiet F A , Kingma A W , van der Slik W , Halie M R
Published: January 2020

A capillary gas-chromatographic method with nitrogen-phosphorus detection is used to determine simultaneously urinary 1,3-diaminopropane, monoacetyl-1,3-diaminopropane, putrescine, monoacetylputrescine, cadaverine, monoacetylcadaverine, spermidine, N1-acetylspermidine, N beta-acetylspermidine, spermine, N1-acetylspermine, isoputreanine, N-(3-aminopropyl)pyrrolidin-2-one, and putreanine. The compounds are isolated by adsorption onto silica and converted into their methyl-heptafluorobutyryl derivatives. We give quality-control data and age-dependent "normal" values for urinary excretion of these analytes from 51 apparently healthy control subjects. Normal values for 31 adults are compared with those reported in the literature. Monoacetyl-1,3-diaminopropane and N1-acetylspermine are identified by mass fragmentography. We applied the method to monitor chemotherapeutic treatment of a patient with advanced non-Hodgkin's lymphoma; we identified by mass spectrometry N1,N12-diacetylspermine in this patient's urine.
Are specimens with "at risk" biochemical profiles more likely to be infectious for hepatitis B virus?
Authors: Burnett L , Whitfield J B , Nightingale B N
Published: January 2020

The potential infectivity of 640 plasma specimens with various biochemical profiles was directly assessed by hepatitis B virus (HBV) DNA dot-hybridization. We found that specimens with "at risk" biochemical profiles typical of various forms of liver disease were not significantly more likely to carry HBV than the general patient population. Specimens containing HBV cannot be distinguished from non-infectious specimens by any simple biochemical tests, including aminotransferases and bilirubin. The only predictive feature of HBV-positive samples was that they were more likely to be labeled as "biohazardous" by the medical staff, but even this was not always the case.
Use of Mahalonobis generalized distance in interpreting low-resolution gas-chromatographic profiles of urinary steroids.
Authors: Davies T G , Griffin K E
Published: January 2020

We used low-resolution gas-chromatography of urinary steroid metabolites, as their trimethylsilyl ethers, in conjunction with the Mahalonobis generalized distance to assess the analyses in terms of a multivariate normal distribution in two populations of women: 18-50 years old and older. We compare the use of this method of interpretation, presenting several cases to illustrate the use of this approach in a routine clinical chemistry laboratory. The improved accuracy of classification as abnormals and to the ability to identify an analysis result as abnormal, even when values for all the analyses fall within the univariate 95% regions of each constituent.
Liquid-chromatographic determination of dolichols in urine.
Authors: Turpeinen U
Published: January 2020

A reversed-phase "high-performance" liquid chromatographic assay for dolichols-18, -19 and -20 in urine is described. Dolichols are extracted from urine by using C18 cartridges and are chromatographed with a mobile phase consisting of 2-propanol/methanol, the effluent being monitored at 210 nm. The useful lower limit of sensitivity for quantification is 4 pmol (5 ng) of each dolichol per 5-microL injection, corresponding to 1.6 nmol (2 ng) per liter of urine. Heneicosaprenol is satisfactory as the internal standard. Peak heights and the amounts of dolichols applied to the column are linearly related from 4 to 110 pmol. Mean analytical recovery was 71%. For three different concentrations the mean within-assay CV was 6.4%, the between-assay CV 11%. The normal reference interval of total dolichols found for healthy adults was 17-101 micrograms/24 h (n = 30) or 1.9-11 micrograms per millimole of creatinine (n = 39). I determined the distribution of the main dolichols in urine and applied the assay also for samples from alcoholics.
Simple spectrophotometric quantification of urinary excretion of glycosaminoglycan sulfates.
Authors: Panin G , Naia S , Dall'Amico R , Chiandetti L , Zachello F , Catassi C , Felici L , Coppa G V
Published: January 2020

We describe a simple, rapid, precise, and sensitive spectrophotometric method for measuring urinary glycosaminoglycan (GAG) sulfate excretion. The GAG sulfates are precipitated with cetylpyridinium chloride, resuspended in water, and mixed with the basic dye 1,9-dimethylmethylene blue to produce a complex with the polyanionic molecule of sulfated GAGs. Absorbance is read at 535 nm. The standard curve for reaction was linear up to 12 micrograms of the different GAGs: dermatan sulfate, heparan sulfate, keratan sulfate, chondroitin 4-sulfate, and chondroitin 6-sulfate. Within- and between-run precision (CV), measured at three different GAG concentrations (normal and pathological), varied from 1.6% to 2.5% and from 1.8% to 4.5%, respectively. Analytical recovery ranged from 71% to 107%. Urinary GAG excretion, measured by this procedure, correlates (r = 0.837; p less than 0.001) with the values obtained with the borate-carbazole reaction (Anal Biochem 1962;4:330-4).
Quality assessment of determinations of serum fructosamine in 33 clinical chemistry laboratories.
Authors: Baker J , Metcalf P , Tatnell M , Lever M , Johnson R
Published: January 2020

We investigated the analytical performance of fructosamine measurement in 33 routine clinical chemistry laboratories. We prepared 12 human control sera spanning a range of nondiabetic and diabetic fructosamine concentrations and assigned target values by using commercial reagents and a Cobas Bio centrifugal analyzer. Each control serum was analyzed by participating laboratories on two separate occasions. Averaged results were compared with target values, and systematic error was determined from slope and intercept regression coefficients. Overall, we found no significant (p greater than 0.05) slope or intercept bias, although slight nonlinearity was found with bichromatic instruments. Random error was determined from the standard error of estimate and from duplicate measurements. We found a median interlaboratory CV of 5.36% and similar analytical performance with all automated instruments used. The median random error with manual techniques was 18.1%. We conclude that fructosamine measurement as currently performed in routine laboratories is sufficiently accurate and reliable to function as an index of blood glucose control in diabetic patients.
Evaluation and comparison of commercially available pregnancy tests based on monoclonal antibodies to human choriogonadotropin.
Authors: Gelletlie R , Nielsen J B
Published: January 2020

We evaluated eight pregnancy tests: Tandem Icon, beta-hCG Rapid, Pregnastick (immunoenzymometric assays), Neo-Pregnosticon (direct hemagglutination), Pregnospia (sol particle immunoassay), Neo-Planotest (latex agglutination), Gravindex beta-hCG, and beta-hCG Slide Test (both latex-agglutination inhibition), all of which detect human choriogonadotropin (hCG) in urine. We investigated the limits of detection and the responses to the following substances: human lutropin, protein, and blood, and high concentrations of hCG. Using 100 patients' samples, we assessed the diagnostic specificity and sensitivity as well as the accuracy of each kit. The detection limits for Tandem Icon, beta-hCG Rapid, Neo-Pregnosticon, Pregnospia, Neo-Planotest, and Gravindex beta-hCG were as stated by the manufacturers. Only Neo-Planotest gave a false-positive result for lutropin. The three immunoenzymometric assays were not affected by protein or blood, but of these only Tandem Icon did not exhibit prozoning. The five other kits gave false-positive or false-negative results for protein and blood. Tandem Icon performed best, being quick and easy to use and without susceptibility to interfering substances.
Concentrations of zinc, iron, molybdenum, arsenic, and lithium in cerebrospinal fluid of patients with brain tumors.
Authors: el-Yazigi A , Al-Saleh I , Al-Mefty O
Published: January 2020

We used flameless atomic absorption spectrophotometry to measure concentrations of Fe, Mo, Li, As, and Zn in cerebrospinal fluid (CSF) of patients with malignant brain tumors benign brain tumors, non-brain malignant tumors and control (non-neoplastic disease) patients. Mean (and SD) concentrations (microgram/L) of these elements in the control group were 62.7 (28.7) for Fe, 6.8 (4.8) for Mo, 0.7 (2.0) for Li, 1.3 (0.7) for As, 7 (5.9) for Zn. We could detect Li in less than 53% of controls. Zn concentrations in CSF of patients with astrocytoma (malignant brain tumor), benign brain tumors, or non-brain tumors were significantly (p less than 0.05) less than in control patients; the ratios for mean concentrations of Zn in tumor patients/control patients for the above groups were 0.3, 0.20, and 0.17, respectively. Concentrations of As in CSF of patients with non-brain malignant tumors were significantly (p less than 0.05) higher than in the controls; the ratio for mean CSF concentration of As in patients with non-brain tumors/control patients was 2.9. Differences in the concentrations of Fe, Li, or Mo among the various groups were nonsignificant.
Laboratory assessment of three new monitors of blood glucose: Accu-Chek II, Glucometer II, and Glucoscan 2000.
Authors: Brooks K E , Rawal N , Henderson A R
Published: January 2020

We describe a laboratory assessment of three new monitors of blood glucose concentrations: the Boehringer "Accu-Chek II" (B), the Ames "Glucometer II" (A), and the Lifescan "Glucoscan 2000" (L). Inherent imprecision (CV) of each monitor was less than 2%. Maximum difference between individual monitors of the same type was less than or equal to 0.5 mmol/L. The volume of blood applied to the test strips is not critical, but duration of blood incubation or color development should be precise. Two types of test strips retained sufficient color 48 h after development to allow checking of the original measurement, and would be suitable as quality-control "spot" checks. Correlation coefficients for results for whole-blood glucose vs those for serum glucose (measured with the Beckman ASTRA-8) were: 0.992 (B), 0.967 (A), and 0.988 (L). Bias plots of these data showed positive bias for A (0.45 mmol/L) and L (0.17 mmol/L) in relation to serum-glucose measurements, but a negative bias of 0.32 mmol/L for B. Calibration solutions are not interchangeable. Although these versions of the monitors are probably not analytically superior to earlier models, they are easier to use.
Hemoglobin, electrolytes, and other major clinical laboratory analytes as measured with a physician's office analyzer, the Kodak DT60.
Authors: Hicks J M , Iosefsohn M
Published: January 2020

We evaluated the Kodak DT60 analyzer, to assess its suitability for use in the physician's office setting. The DT60 Analyzer is based on the same multilayer film technology as used in the Ektachem 400 and 700. We compared results obtained with DT60 for all the analyses currently available for use in this instrument (Na+, K+, Cl-, glucose, urea nitrogen, uric acid, total bilirubin, total protein, amylase, cholesterol, and triglycerides) with results from a Kodak Ektachem 700 Analyzer and from other laboratory procedures. Results for hemoglobin were compared with those from a Coulter Counter Analyzer. For all analytes, linearity of the standard curve for various dilutions of Ektachem calibrators was within the manufacturer's claims. CVs for within-run precision ranged from 0.8% to 5.4%, run-to-run CVs ranged from 1.6% to 7.5%. Except for amylase, comparisons with other methods were generally very good. The only interference we observed was that of hemoglobin in the bilirubin assay. Calibration was stable for longer than one month. We also compared the performance of a skilled operator with that of an unskilled operator and of a physician.
Stability of NADPH: effect of various factors on the kinetics of degradation.
Authors: Wu J T , Wu L H , Knight J A
Published: January 2020

Seeking to minimize degradation of NADPH during storage, reagent preparation, and assays, we investigated the effects of pH, temperature, and ionic strength as well as the effects of phosphate and acetate. NADH was also included for comparison. Our results indicate that the rate of degradation of NADPH is proportional most importantly to temperature and concentrations of hydronium ion, but also to concentrations of phosphate and acetate. The degradation rate decreased with increasing ionic strength at neutral pH, but increased slightly at lower pH. NADPH generally is less stable than NADH under the same conditions. The reaction orders with respect to hydronium ion and anions were near 1 for NADH degradation reactions, about 0.5 for NADPH. Rate constants for NADH and NADPH differed more at higher pH and lower phosphate and acetate concentrations.
Imprecision of quantification of serum protein fractions by electrophoresis on cellulose acetate.
Authors: Kahn S N , Strony L P
Published: January 2020

We studied the precision of densitometric quantification of the protein zones resolved by cellulose acetate electrophoresis. Replicate analyses of patients' samples by a single technologist showed mean CVs ranging from 2.9% for serum albumin to 9.5% for alpha 1-globulin. There were marked differences in measurements obtained by replicate analysis of the same samples by two experienced technologists. We calculated what changes in fractional concentrations would be analytically significant and concluded that densitometry of cellulose acetate electrophoretograms can only be semi-quantitative. We suggest that visual interpretation of high-resolution electrophoretic patterns by a trained observer can replace densitometry in most cases.
Loss of coproporphyrin by centrifuging urine samples before liquid-chromatography.
Authors: Hill R H , Bailey S L
Published: January 2020

We have previously reported a "high-performance" liquid-chromatographic procedure for urinary porphyrins. While attempting to automate this procedure, we discovered that coproporphyrin could be partly or completely lost from urine samples if they were centrifuged or filtered before analysis. The loss is related to the amount of precipitate in each sample, acidic urines showing the greatest losses. If samples are alkalinized before centrifugation, the loss is prevented.
Formic and lactic acidosis in a fatal case of methanol intoxication.
Authors: Shahangian S , Ash K O
Published: January 2020

A 33-year-old white man was admitted to the University of Utah Hospital after about 30 h of various symptoms, including blurred vision and (eventually) severe left flank and back pain. Upon admission, his serum pH was 6.80 and serum bicarbonate concentration (calculated from pCO2 and pH) was 3.9 mmol/L. The etiology for the acidosis became apparent 10 h after admission, when assay of the serum prepared from a blood specimen obtained at admission revealed a methanol concentration of 74 mmol/L (2.4 g/L). At this time the patient was placed on hemodialysis and intravenously infused with sodium bicarbonate. The methanol concentration in serum had decreased to 21 mmol/L 2 h later. Formate and lactate concentrations were, respectively, 10 and 23 mmol/L in serum sampled 4.5 h after hospitalization, at which time serum pH was 6.91 and bicarbonate concentration 7 mmol/L. The patient eventually died with extensive neuropathy.
Parathyrin (parathyroid hormone): metabolism and methods for assay.
Authors: Armitage E K
Published: January 2020

Parathyrin (parathyroid hormone) radioimmunoassay is a commonly ordered endocrine assay. I discuss here of the metabolism of the hormone and the effect information on this metabolism has had on the development of radioimmunoassays for parathyrin. Although radioimmunoassay is the most widely accepted technique for the routine assay for parathyrin, "high-performance" liquid chromatography, cytochemical bioassay, and homologous bioassay have also been developed for this analyte. Accordingly, I briefly review the clinical utility of these assays in terms of their ability to assess the functional activity of the parathyroid gland.
Automated determination of urinary creatinine without sample dilution: theory and practice.
Authors: Kroll M H , Chesler R , Hagengruber C , Blank D W , Kestner J , Rawe M
Published: January 2020

The rate of the Jaffé reaction depends on the concentration of sodium hydroxide; the pseudo-first-order rate constant of the reaction, at 37 degrees C in 10 mmol/L picrate solution, is 0.004 mmol/L. We formulated an automated method to determine urinary creatinine directly without manual sample dilution. The conditions are as follows: 10 mmol/L picrate and 60 mmol/L sodium hydroxide (final concentrations); ratio of sample to final volume, 1:41; temperature, 37 degrees C; wavelengths of measurement, 500 or 510 nm; interval of measurement, 30 to 90 s; and mode of measurement, kinetic. Determinations of creatinine in patients' samples by the new method compared favorably with those obtained with the AutoAnalyzer and aca. The run-to-run CVs were 3.6% or less, and the method was accurate for concentrations of creatinine up to 3000 mg/L. We recommend this method as a good replacement for the AutoAnalyzer or aca methods.
Diagnostic value of thyrotropin concentrations in serum as measured by a sensitive immunoradiometric assay.
Authors: Bassett F , Eastman C J , Ma G , Maberly G F , Smith H C
Published: January 2020

A new, highly sensitive immunoradiometric thyrotropin (TSH) assay involving solid-phase-coupled monoclonal antibodies (Boots-Celltech Sucrosep IRMA-TSH) has been evaluated in a wide variety of patients with thyroidal and nonthyroidal illnesses and the results compared with those obtained by conventional diagnostic TSH RIAs. The sensitivity of the present assay ranged from 0.036 to 0.1 milli-int. unit/L (mean 0.056). TSH, measurable in serum of each of 128 euthyroid patients, ranged from 0.1 to 6.3 milli-int. units/L (mean 1.7, SD 1.1). Similar concentrations were found in 15 healthy pregnant women. TSH was undetectable in 27 hyperthyroid patients, of whom six were tested with thyroliberin stimulation and failed to respond. The mean TSH concentration measured in 62 seriously ill hospital patients of 2.7 (SD 2.5) milli-int. units/L was significantly higher (p less than 0.05) than in the euthyroid patients. Basal values and peak TSH responses to thyroliberin testing correlated well (r = 0.63, n = 48), irrespective of clinical diagnosis. We conclude that the present assay readily discriminates between euthyroid and hyperthyroid patients and should replace conventional TSH RIAs in diagnostic laboratories.
Changes in mass and catalytic activity concentrations of aspartate aminotransferase isoenzymes in serum after a myocardial infarction.
Authors: Niblock A E , Jablonsky G , Leung F Y , Henderson A R
Published: January 2020

We used an RIA and inhibition of enzyme activity to monitor the changes in mass and catalytic concentrations of the aspartate aminotransferase (EC 2.6.1.1;AST) isoenzymes in serum after myocardial infarction. Cytosolic (c-AST) and mitochondrial (m-AST) forms of AST were present in sera from all 38 of our patients. Although the immunological and catalytic concentrations of both isoenzymes correlated well with the size of the infarct, c-AST gave a better measure than did m-AST. About 20% of the total enzyme activity at peak activity was from the mitochondrial isoenzyme. Both isoenzyme activities peak at very nearly the same time, but m-AST has the longer half-life. Immunological evidence of the mitochondrial isoenzyme can be detected in serum for at least eight days after the infarct. The presence of left ventricular failure produces greater serum isoenzyme activities than in those without failure.
Monoject Samplette capillary blood container with serum separator evaluated for collection of specimens for therapeutic drug assays and common clinical-chemical tests.
Authors: Landt M , Norling L L , Steelman M , Smith C H
Published: January 2020

The Monoject Samplette (Sherwood) capillary serum-separator tube was evaluated for use in pediatric capillary blood collection. When patients' values for eight common clinical-chemical tests and five therapeutic drugs were compared with values from specimens concomitantly collected in plain Caraway tubes, only chloride and total CO2 were significantly different. The chloride differences (range 0-2 mmol/L) were considered to be clinically insignificant. Higher CO2 values in Samplette specimens were apparently ascribable to decreased loss to the atmosphere. Samplette values for therapeutic drugs were higher than corresponding Caraway values, but only the differences for digoxin were judged to be clinically significant. Both recoverable serum and the incidence of hemolysis were lower in Samplette specimens than in Caraway specimens. Storage of serum over the clots (with separator material interposed) in Samplettes for 24 h had no clinically significant effect on results for glucose or potassium. Storage of specimens for as long as 24 h had no effect on theophylline, phenytoin, and gentamicin concentrations, but phenobarbital reproducibly decreased after 24 h. We conclude that the Samplette serum-separator tube is suitable for the collection of capillary blood for many of the chemical tests commonly ordered for pediatric patients.
Chemiluminescent labeled-antibody assay for thyroxin in serum, with magnetic separation of the solid-phase.
Authors: Sturgess M L , Weeks I , Mpoko C N , Laing I , Woodhead J S
Published: January 2020

A chemiluminescent labeled-antibody immunoassay has been developed for measurement of total thyroxin (T4) in serum. Monoclonal antibodies to T4 labeled with a chemiluminescent acridinium ester are used. Serum samples are incubated with the labeled antibodies and a thyroxin-rabbit immunoglobulin conjugate, then reacted with magnetizable particles containing sheep anti-rabbit immunoglobulin. The total reaction time is 40 min. The chemiluminescence intensity of the solid-phase immune complexes is inversely proportional to the concentration of T4 in the sample. The sensitivity of the assay is 1 nmol/L, and the working range of 20-190 nmol/L is characterized by CVs less than or equal to 10%.
A peroxidase-coupled kinetic enzymatic procedure evaluated for measuring serum and urinary creatinine.
Authors: Goren M P , Osborne S , Wright R K
Published: January 2020

We evaluated an enzymatic procedure for the automated determination of serum and urinary creatinine. The procedure was sensitive and precise for serum creatinine concentrations as low as 3 mg/L, and the standard curve was linear to 200 mg/L. Measurements of creatinine in clinical serum and urine specimens agreed with those obtained by two other enzymatic methods and four picric acid methods. There was no interference from picrate-reactive substances tested. Among other substances, bilirubin (50-100 mg/L) interfered negatively with the assay, decreasing apparent creatinine concentrations by as much as 6 mg/L. The advantages of specificity, speed, and convenience make this enzymatic procedure an attractive primary or secondary method for creatinine determinations in clinical laboratories.
Estimation of free thyroid hormone concentrations in the clinical laboratory.
Authors: Wilke T J
Published: January 2020

A multiplicity of tests have come into routine use for the estimation of the concentrations of free thyroid hormones in serum and plasma since the introduction, almost three decades ago, of the hypothesis that only the free thyroid hormone is metabolically active. Most of these tests give estimates of considerable diagnostic value, although results may be unreliable in some clinical situations. This review outlines the methods currently available for estimating free thyroid hormones and highlights the extrathyroidal and physiological factors influencing the results of such tests, particularly for the analog-based techniques.
Effect of phytohemagglutinin on concentrations of glucocorticoid receptors in lymphocytes from patients with connective tissue diseases.
Authors: Murakami T , Inokuma S , Ohsawa N , Takaku F
Published: January 2020

We examined the effect of phytohemagglutinin (PHA) on glucocorticoid receptors in lymphocytes, using peripheral mononuclear leukocytes from patients with connective tissue diseases. Glucocorticoid receptor concentrations and dissociation constants (Kd) for [3H]dexamethasone binding to lymphocytes from patients with rheumatoid arthritis, Sjögren's syndrome, and other connective tissue diseases did not differ significantly from values for normal volunteers. Kd values correlated positively with glucocorticoid receptor concentrations after PHA stimulation both in normal volunteers and in patients with connective tissue diseases. The correlations (r values) for the control group and patients were not significantly different.
Two-site time-resolved immunofluorometric assay of human insulin.
Authors: Toivonen E , Hemmilä I , Marniemi J , Jørgensen P N , Zeuthen J , Lövgren T
Published: January 2020

We describe a two-site "sandwich"-type time-resolved immunofluorometric assay for human insulin, based on use of two monoclonal antibodies with different specificities. The first antibody is immobilized on the surface of microtiter plate strip wells, the other is labeled with Eu3+. Serum samples can be assayed with one incubation step; two incubation steps are required when plasma samples are assayed. After the immunoreactions are complete, the bound fraction of Eu3+-label is quantified by dissociating it in a fluorescence-enhancement solution and measuring its fluorescence with a fluorometer with time-resolution. The sensitivity of the assay is 0.24 micro-int. units/mL. The standard curve is linear from 0.24 to 2400 micro-int. units/mL.
Measurement of alpha-glucosidase activity in serum from patients with cystic fibrosis or pancreatitis.
Authors: Porter W H , Jennings C D , Wilson H D
Published: January 2020

We measured the activity of a non-lysosomal alpha-glucosidase with pH optimum near 6.0 in serum from a wide variety of patients, using the fluorogenic substrate, 4-methylumbelliferyl-alpha-D-glucopyranoside. Acutely ill patients with cystic fibrosis (CF) demonstrated significant increases in alpha-glucosidase compared with CF outpatients. The former group of CF patients experienced far more severe chronic pulmonary disease than did the latter, whereas both groups had similar degrees of gastrointestinal impairment. Patients with pancreatitis associated with trauma or complicated by severe necrosis, hemorrhage, or abscess also displayed greater increases in alpha-glucosidase than did patients with uncomplicated (edematous) pancreatitis. For CF outpatients and patients with either edematous pancreatitis or pancreatic cancer, the alpha-glucosidase activity was similar to that for the general hospital-patient population. Corresponding changes were not observed for other measured serum glycosidases (alpha-fucosidase, alpha-mannosidase, beta-glucuronidase, beta-N-acetylglucosaminidase). Measurement of serum alpha-glucosidase may be of value in assessing the clinical course in CF and in differentiating necrotizing from edematous pancreatitis.
Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy-dispersive x-ray fluorescence. 2: Determination of abnormal lavage contents and verification of the results.
Authors: Maier E A , Dietemann-Molard A , Rastegar F , Heimburger R , Ruch C , Maier A , Roegel E , Leroy M J
Published: January 2020

We applied energy-dispersive x-ray fluorescence to the determination of abnormally present elements or abnormal concentrations of elements in human broncho-alveolar lavage fluids. The low detection limits and the ability to perform multi-elemental analysis permit one to establish or confirm occupational exposure of workers. We also describe different methods used to check our method and our results. We report examples of abnormal compositions of broncho-alveolar lavages containing W, Ce, La, Nd, I, Fe, or Ni. We discuss the limits of the method for characterizing silicosis or asbestosis.
Ascorbic acid interference in reagent-strip reactions for assay of urinary glucose and hemoglobin.
Authors: Zweig M H , Jackson A
Published: January 2020

Vitamin C (ascorbic acid), commonly taken as a dietary supplement and excreted in the urine, can interfere with peroxidase redox indicator systems such as those used in reagent-strip tests for urinary glucose and hemoglobin. We investigated whether the concentrations of ascorbic acid in urine after modest supplementary doses of vitamin C are high enough to interfere with such dipstick tests. After adding glucose or hemoglobin to urine collected from persons not taking vitamin C and from persons taking 350 to 1000 mg of vitamin C daily, we tested four reagent strips for interference and found that these commonly taken doses did frequently interfere with all test systems examined.