bluuebunny/crossref_metadata_2025 huggingface dataset:
Isoelectric focusing in agarose: classification of genetic variants of alpha 1-antitrypsin.
Authors: Buffone G J , Stennis B J , Schimbor C M
Published: January 2020

Polyacrylamide has been the matrix of choice for isoelectric focusing owing to the virtual absence of electroendosmosis in this medium. Certain inherent limitations associated with polyacrylamide have prompted some investigators to use low-electroendosmosis agarose for isoelectric focusing, but with limited success thus far. We have developed a method for isoelectric focusing in agarose for the classification of alpha 1-antitrypsin variants. Sera are applied directly to agarose gels containing a pH 4-5 ampholyte mixture, focused for less than 1 h, and directly immunofixed. Resolution of major bands is equivalent to polyacrylamide, and Pi M subtypes can be distinguished without the use of a separator. This application demonstrates the high resolution of isoelectric focusing in agarose, a more practical and convenient matrix than polyacrylamide.
Direct determination of cadmium in urine with use of a stabilized temperature platform furnace and Zeeman background correction.
Authors: Pruszkowska E , Carnrick G R , Slavin W
Published: January 2020

In this determination of Cd in urine, simple aqueous standards were used to which NaCl and the matrix modifier were added. The urine was diluted fivefold with water. The mean analytical recovery of added Cd for urine samples was 101%, with individual variations of less than 4%. We used the stabilized temperature platform furnace, Zeeman background correction, pyrolytically coated graphite tubes, and (NH4)2HPO4 plus HNO3 as a matrix modifier. The sensitivity of the method provided a characteristic amount of 0.35 pg of Cd per 0.0044 A X s, obtained with integrated absorbance readings. The absolute Cd detection limit in urine was 0.15 pg, corresponding to 0.04 microgram/L of urine. Lower relative detection limits for Cd in urine can be attained if the analytical situation demands it.
Effect of variations in room temperature on measured values of blood gas quality-control materials.
Authors: Ong S T , David D , Snow M , Hansen J E
Published: January 2020

We compared four commercial quality-control materials equilibrated in sealed ampoules at 21 or 26 degrees C in three models of blood gas machines and found po2 differences of about 13.3 Pa (10 mmHg) for an aqueous mixture with hemoglobin; about 6.7 Pa (5 mmHg) for two aqueous buffers without hemoglobin, and none for a fluorocarbon-containing emulsion. Differences for pco2 and pH were small but statistically significant. Variability within machines for pco2, po2, and pH was small but differences among machines were large, especially for po2. These results emphasize that aqueous solutions and hemoglobin-containing mixtures used for proficiency testing and quality control should be equilibrated at the temperature recommended by the manufacturer, opened, and sampled promptly.
Development and analytical performance of a functional assay for fibrinogen on the Du Pont aca analyzer.
Authors: Siefring G E , Riabov D K , Wehrly J A
Published: January 2020

A method for determination of functional fibrinogen has been developed for the Du Pont aca discrete clinical analyzer. This fully automated assay is based on the rate of fibrin turbidity formation when thrombin is added to the test sample. The rate of this reaction is enhanced by added calcium chloride and dextran. The assay range is from 0.50 to 8.00 g/L. Within-run reproducibility studies at the medical decision level of 1.0 g/L showed a CV of 2.5%. There was no interference by heparin up to 10 USP units per milliliter of plasma.
Simultaneous determination of haloperidol and its reduced metabolite in serum and plasma by isocratic liquid chromatography with electrochemical detection.
Authors: Korpi E R , Phelps B H , Granger H , Chang W H , Linnoila M , Meek J L , Wyatt R J
Published: January 2020

We describe a liquid-chromatographic method for simultaneous quantification of haloperidol and its reduced metabolite in plasma and serum. Haloperidol and reduced haloperidol are concentrated from blood samples by liquid/liquid extraction into a hexane/isoamyl alcohol mixture, with chlorohaloperidol as the internal standard. For chromatographic separation we used a reversed-phase cyano-bonded column and a mobile phase of pH 6.8 phosphate buffer/acetonitrile (55/45 by vol). Haloperidol and its reduced metabolite are detected electrochemically at +0.90 V potential between the working and reference electrodes. As little as 0.5 ng per injection is detectable. Within- and between-day CVs for determinations of haloperidol and reduced haloperidol ranged from 4 to 7% each at a concentration of 10 micrograms/L. Haloperidol concentrations measured by this method correlated well with those by gas-chromatography with nitrogen-sensitive detector and by radioimmunoassay. The present method can be used to study the effects of haloperidol on the central nervous system. It is simple enough for use in clinical laboratories that are monitoring haloperidol concentrations in the blood of psychiatric patients.
Immunonephelometric determination of retinol-binding protein in serum and urine.
Authors: Parviainen M T , Ylitalo P
Published: January 2020

An immunonephelometric method developed for measurement of retinol-binding protein (RBP) in serum and urine can detect it in concentrations of about 30 micrograms/L, which is in the lower limit of its normal concentration in urine (range 0-0.56 mg/L; mean +/- SD 0.19 +/- 0.15; n = 44). Urinary RBP was increased (range 0.93-29.5 mg/L) in all of 25 urine specimens from 13 subjects being treated with aminoglycoside (tobramycin). Urinary excretion of RBP was correlated (r = 0.83) with the excretion of beta 2-microglobulin. The within-assay and day-to-day precision (CV) was determined over the detection range of 0.03-8 mg/L. Within these limits the corresponding CVs varied from 4 to 27% and from 8 to 30%, respectively. The method had fairly good precision within the optimal measuring range of approximately 0.4 to 4.5 mg/L for both urine and 20-fold diluted serum samples. For various RBP concentrations our analytical recovery was 89-114% of added RBP. Results by this method correlated well (r = 0.96, n = 24) with those by a radial immunodiffusion method.
Liquid-chromatographic determination of cephalosporins and chloramphenicol in serum.
Authors: Danzer L A
Published: January 2020

A "high-performance" liquid-chromatographic technique involving a radial compression module is used for measuring chloramphenicol and five cephalosporin antibiotics: cefotaxime, cefoxitin, cephapirin, and cefamandol. Serum proteins are precipitated with acetonitrile solution containing 4'-nitroacetanilide as the internal standard. The drugs are eluted with a mobile phase of methanol/acetate buffer (30/70 by vol), pH 5.5. Absorbance of the cephalosporins is monitored at 254 nm. Standard curves are linear to at least 100 mg/L. The absorbance of chloramphenicol is monitored at 254 nm and 280 nm, and its standard curve is linear to at least 50 mg/L. The elution times for various other drugs were also determined, to check for potential interferents.
Urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid, 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid, and 5-hydroxy-3-indoleacetic acid determined by liquid chromatography with electrochemical detection.
Authors: Fujita K , Maruta K , Ito S , Nagatsu T
Published: January 2020

We describe a simple liquid-chromatographic assay of urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid, 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid, and 5-hydroxy-3-indoleacetic acid with electrochemical detection, with direct injection of the sample. The first two analytes are measured simultaneously; 5-hydroxy-3-indoleacetic acid is measured separately. Chromatographic conditions for assay of the three were: column temperature, 65 and 60 degrees C; mobile phase, potassium phosphate buffer (0.2 mol/L, pH 3.0) for 6 min, then potassium phosphate buffer plus acetonitrile (9/1 by vol) for 20 min; flow rate, 0.7 mL/min; oxidation potential, 600 and 450 mV vs an Ag/AgCl reference electrode; and sensitivity, 40 and 160 nA at full scale. Values so obtained agreed well with those obtained for samples that were first solvent-extracted.
Rapid acetylcholinesterase screening test for neural tube defect.
Authors: Hay D L , Ibrahim G F , Horacek I
Published: January 2020

A 5-min optimized automated assay for measuring acetylcholinesterase (AChE) and total cholinesterase (ChE) in amniotic fluids is described in which a centrifugal analyzer is used. Total ChE was measured by using acetylthiocholine iodide and monitoring the color developed after 5,5'-dithiobis(2-nitrobenzoic acid) is added. We evaluated four direct and indirect procedures for measuring AChE in which thiocholine is generated. These methods involve either the specific enzyme inhibitors ethopropazine and BW284C51 or the specific substrates S-butyrylthiocholine and acetyl-beta-methylthiocholine. We found the last method distinguishes normal pregnancies most efficiently from those with neural tube defect. Filtering samples through 0.22-micron membrane filters before analysis decreased the incidence of false positives. Significantly increased AChE concentrations were noted in all abnormal pregnancies (n = 45) and in 4.8% of normal pregnancies (n = 310). The rapid AChE assay involving acetyl-beta-methylthiocholine, when applied alongside a rapid alpha-fetoprotein assay, increases the efficiency of screening programs for pregnancies with neural tube defect to 99.4%. It also identifies samples with negative results for alpha-fetoprotein that require further examination by the sensitive gel-electrophoretic test for AChE.
Reference intervals for amylase isoenzymes in serum and plasma of infants and children.
Authors: Gillard B K , Simbala J A , Goodglick L
Published: January 2020

Measurement of pancreatic (P) and salivary-like (S) amylase isoenzyme activity in serum of adults is useful as an indirect indicator of pancreatic and salivary gland exocrine dysfunction. To extend the use of this assay to the pediatric population, we measured amylase isoenzymes in 546 serum and plasma samples and defined normal reference intervals for the P and S isoenzymes as a function of age in newborns, infants, and children. The mean activity of P isoenzyme in newborns is 3% of that of adults, begins to increase at seven to eight months, and reaches adult values by five years. The mean activity of S isoenzyme in serum is 32% of the adult mean at birth, begins to increase by three to four months, and reaches adult values by 19 months; children five to 12 years old have slightly higher values than adults. These changes with age underscore the importance of the use of age-matched reference intervals when serum amylase isoenzyme activities are measured as diagnostic indicators.
Technical considerations in the use of "high-performance" liquid chromatography in therapeutic drug monitoring.
Authors: Giese R W
Published: January 2020

I review the methodology of "high-performance" liquid chromatography as applied to therapeutic drug monitoring. Aside from direct injection of sample, sample cleanup involves miscible and immiscible organic solvent extractions, solid-phase extraction, and size separations. Column considerations are bonded phases, column dimensions, particle size, guard columns, stability, pH range, and reproducibility. In a section on mobile phase, the reversed-phase mode is discussed along with temperature and degassing. Absorbance and fluorescence detectors are used most commonly. The parameters "capacity factor," "efficiency," and "asymmetry value" are helpful for interpreting chromatograms, as are the aspects of peak tailing, peak quantitation, "complex solutes," and "crowded chromatograms." Finally, automation, competing methodology, and prospects are discussed.
Specific micro-radioimmunoassay for prednisolone in serum.
Authors: Olivesi A , Smith D S , White G W , Pourfarzaneh M
Published: January 2020

Use of an 125I radioimmunoassay involving antiserum coupled to magnetizable cellulose, after prednisolone-21-phosphate interference is removed by dichloromethane extraction at pH 7.4 and endogenous glucocorticoid interference is removed by selective chemical derivatization with Girard's Reagent T [(carboxymethyl)trimethylammonium chloride hydrazide], allows determination of prednisolone in 10 microL of serum. Results correlate well with those of an established liquid-chromatographic method for separating prednisolone from its metabolites.
Transcutaneous and capillary pCO2 and pO2 measurements in healthy adults.
Authors: Wimberley P D , Pedersen K G , Thode J , Fogh-Andersen N , Sørensen A M , Siggaard-Andersen O
Published: January 2020

Transcutaneous carbon dioxide and oxygen tensions (tc-pCO2 and tc-pO2) were measured in seven healthy adult volunteers during hyperventilation in atmospheric air and during CO2 inhalation. Three skin sensors were applied to each subject: an O2 electrode, a CO2 electrode, and a combined O2-CO2 electrode, each heated to 44 degrees C. We observed close correlation between tc-pCO2 and capillary-pCO2, the relation being close to that calculated from the anaerobic temperature coefficient of pCO2 in blood. For O2, on the other hand, the relationship between transcutaneous and capillary values appeared more complex. Electrode drift during in-vivo monitoring was greater for pCO2 (up to 12%) than for pO2 (up to 7%), but generally we observed no differences in drift between the combined and the single electrodes. We conclude that tc-pCO2 measured with a single or a combined electrode reliably predicts capillary-pCO2 in healthy adults and that changes are rapidly observed. Our conclusions regarding tc-pO2 values are less definite because of uncertain interpretation of the capillary-pO2 values.
Transcutaneous carbon dioxide for short-term monitoring of neonates.
Authors: Kost G J , Chow J L , Kenny M A
Published: January 2020

We studied transcutaneous pCO2 monitoring in 70 neonates, most of them premature with respiratory distress syndrome. Measurements were at 44 degrees C. Calibration drift was large in some instances. Least squares linear regression analyses of transcutaneous pCO2 (y) vs arterial pCO2 (x) in kilopascals showed, for all observations (n = 516), for one observation randomly selected from each patient (n = 70), and for the first observation from each patient (n = 70): y = -0.28 + 1.80x, y = 0.01 + 1.74x, and y = 0.73 + 1.63x, respectively. Regression lines for individual patients with 14 or more observations each were not coincident (F = 2.80, p less than 0.002). Transcutaneous pCO2 monitoring was most useful clinically as a means of following short-term trends in arterial pCO2 continuously during extubation and afterward when avoiding re-intubation. In view of the potential for error associated with drift, we recommend that intervals between calibrations be limited to about 3 h.
Simultaneous liquid-chromatographic determination of hypoxanthine, xanthine, urate, and creatinine in cerebrospinal fluid, with direct injection.
Authors: Niklasson F
Published: January 2020

In this method for simultaneously determining hypoxanthine, xanthine, urate, and creatinine in cerebrospinal fluid, centrifuged sample is directly injected on a reversed-phase liquid-chromatographic column. On elution with potassium phosphate buffer the compounds are quantified by their absorbance at 260 nm. Random error (CV) was between 1.2 and 3.4% and analytical recoveries were 99-104% at physiological concentrations.
Use of a solid-state multihead gamma counter in a second-generation system for solid-phase immunoassay.
Authors: Parsons G H , Rogers C H , Polsky-Cynkin R , Wood A M , Miles L E , Rogers A H
Published: January 2020

Simultaneous advances in detector technology and solid-phase separation systems, as well as the availability of powerful desktop computers, have made possible the development of "second-generation" solid-phase immunoassays. These retain the advantages of classical solid phase while significantly accelerating reaction kinetics. Hapten assays--such as for digoxin, thyroxin, and triiodothyronine uptake--in batches of 48 are processed in about 20 min from reagent introduction until hard-copy printout, with minimal operator involvement. The system also functions as a 48-detector gamma counter, capable of counting and reducing data for any 125I-based RIA that can be run in a 12 X 75 mm test tube. System control, data management, and computer screen displays of kinetic data are provided by an unmodified Hewlett Packard HP-87XM computer. User-friendly disc-based software facilitates the creation and storage of counting and data reduction protocols for as many as 30 RIAs from various manufacturers as well as up to 30 of our own assays.
Applications of fast protein liquid chromatography TM in the separation of plasma proteins in urine and cerebrospinal fluid.
Authors: Cooper E H , Turner R , Johns E A , Lindblom H , Britton V J
Published: January 2020

Fast Protein Liquid Chromatography TM (FPLC), in which an anion-exchange column is used, provides rapid separation and reproducible profiling of the plasma proteins in urine and cerebrospinal fluid (CSF). Chromatographic separation of the proteins takes 1 h for urine specimens and 45 min for CSF. The elution sequence from the anion-exchange column is similar to the electrophoretic mobility. Individual proteins have the same retention times independently of which type of specimen is used. The elution characteristics of 21 plasma proteins have been identified. We illustrated some applications of this system, including the profiling of tubular protein-uria, the isolation of Bence Jones proteins from urine, and the investigation of hemoglobin-derived products in the CSF.
New techniques and tools for clinical chemistry.
Authors: Hieftje G M
Published: January 2020

In this paper are described and evaluated several new tools of potential use in clinical chemistry. The first, intended to minimize required sample volumes, is a device with which a total sample volume of 1 microL can be dispensed in the form of 1000 identical aliquots. Any number of such nanoliter aliquots can be taken if larger samples are needed. The second new tool is one for detecting anions or cations separated by ion chromatography. Unlike conventional conductometric detectors used in ion chromatography, the new system offers potential sensitivities in the sub-microgram per liter range and useful operating ranges up to 100 mg/L. The third tool is a scheme for background correction in atomic absorption spectrometry; the new technique requires no special auxiliary sources or double-beam optics. Finally, fluorescence time-decay curves and fluorescence lifetimes are shown to be able to overcome the effects of diffusional quenching and scattering resulting from turbidity of solutions in clinical fluorometry.
A rapid method for repurifying partly degraded radiolabeled steroids.
Authors: Jawad M J , Wilson E A , Vernon M W
Published: January 2020

This rapid method for repurifying radiolabeled steroids from degraded products is based upon differential partitioning of intact and degraded molecules between aqueous-phase solution and anhydrous diethyl ether. Results compare favorably with those by liquid-chromatographic methods.
Kinetics of enzymatic O-methylation: its value in assays for catecholamines in plasma.
Authors: Mason L , Weinkove C
Published: January 2020

The kinetics of enzymatic O-methylation of catecholamines were studied under conditions like those used in the radioenzymatic assay of plasma catecholamines. Inappropriate Michaelis-Menten kinetics and linear approximations of exponential equations were not used. Mathematical analysis indicated the importance of the ratio of methyl donor (S-adenosylmethionine) to substrate (catecholamine) concentration. If the reaction is incomplete, only a large ratio will allow linear approximations between product formed and initial catecholamine concentration. The use of high-concentration internal standards to correct for plasma interference may give erroneous results by reducing this ratio. Accuracy will be improved by ensuring (a) that S-adenosylmethionine is always greatly in excess of catecholamine, (b) that concentrations of added standards are of the same order as for endogenous catecholamine, and (c) that a high activity of enzyme is used, to allow the reaction to reach completion even in the presence of some inhibition.
Myoglobin concentration, creatine kinase activity, and creatine kinase B subunit concentrations in serum during thyroid disease.
Authors: Docherty I , Harrop J S , Hine K R , Hopton M R , Matthews H L , Taylor C J
Published: January 2020

Changes in values for myoglobin, total creatine kinase (EC 2.7.3.2), and creatine kinase B-subunit in the serum of patients with thyroid disease are compared with values for these during the 24-h after myocardial infarction. Concentrations of all three of these muscle-derived proteins were significantly higher than normal in patients with primary hypothyroidism, and declined with treatment. Values for total creatine kinase activity were below-normal in hyperthyroid patients, but increased after treatment. Values for total creatine kinase and, to a lesser extent, myoglobin in hypothyroidism extend into the range of values observed after myocardial infarction. The mechanism of the changes in these analytes in hypothyroidism may be related to increased leakage from skeletal-muscle cells or diminished clearance from the circulation, or both.
Transient creatine kinase-BB activity in serum or plasma after cardiac or respiratory arrest.
Authors: Massey T H , Goe M R
Published: January 2020

We studied the transient appearance of creatine kinase (EC 2.7.3.2) isoenzyme BB, as measured by electrophoresis, in serum or plasma from 19 patients who had just experienced cardiac or respiratory arrest. Creatine kinase BB activity was greatest 0.5 to 3 h after the arrest, with values (measured at 30 degrees C) ranging from 3 to 27 U/L (mean, 7.8 U/L) in 18 patients who were successfully resuscitated. Elimination time for the isoenzyme ranged from 8 to 48 h (mean, 20 h). Elimination t1/2 varied from 4.6 to 16 h for 13 patients from whom adequate serial blood specimens were obtained. We could find no correlation between peak BB activity and eventual case outcome. We attribute this to the near impossibility of drawing a blood specimen exactly when the isoenzyme activity peaks, the instability of creatine kinase BB activity at 37 degrees C, and the fact that nine of these patients died after second or multiple arrests.
Simultaneous measurement of ethosuximide, primidone, phenobarbital, phenytoin, carbamazepine, and their bioactive metabolites by liquid chromatography.
Authors: Ou C N , Rognerud C L
Published: January 2020

A simple, isocratic liquid-chromatographic method was developed for simultaneously measuring ethosuximide, primidone, phenobarbital, phenytoin, carbamazepine, and their bioactive metabolites within 10 min. The chromatographic system involves a Waters' Radial-NOVA PAK C18 reversed-phase column and acetone/methanol/acetonitrile/10 mmol/L phosphate buffer (10/21/8/61 by vol, pH adjusted to 7.95 with NaOH) as mobile phase. The antiepileptic drugs are extracted from 50 microL of serum by mixing with 50 microL of acetonitrile containing 10 mg of tolybarb per liter as internal standard. After centrifugation, 20 microL of the supernate is injected onto the column and eluted with mobile phase at the rate of 2.8 mL/min at ambient temperature. The column effluent is monitored at 200 nm. The method can detect the five antiepileptic drugs in concentrations as low as 0.5 mg/L. Analytical recovery ranges from 98 to 102%. Within-run CV ranged from 2.9 to 5.8% and between-run CV from 4.7 to 7.1%. The method can also be used to measure N-desmethyl-methsuximide, chloramphenicol, and pentobarbital.
Creatine kinase isoenzymes in human cerebrospinal fluid and brain.
Authors: Chandler W L , Clayson K J , Longstreth W T , Fine J S
Published: January 2020

Extracts of normal brains obtained at autopsy and cerebrospinal fluid (CSF) from patients with global brain ischemia were analyzed for creatine kinase (CK; EC 2.7.3.2) isoenzymes. We used both qualitative and quantitative assays (electrophoresis and immunoinhibition). Brain extracts contained CK-BB isoenzyme and mitochondrial CK. In 54 CSF samples free of blood contamination and with total activities ranging from 7 to 2010 U/L (mean 202 U/L), virtually all of the CK activity was due to CK-BB, and none to CK-MM or CK-MB. We conclude that brain contains CK-BB and mitochondrial CK, but lacks CK-MM and CK-MB. After cardiac arrest, CK-BB is released into the CSF. Any CK-MM in the CSF is probably from blood contamination, in which case immunoinhibition with anti-CK-M antibodies accurately quantifies CK-BB.
Tissue proteins in breast cancer, as studied by use of two-dimensional electrophoresis.
Authors: Stastny J , Prasad R , Fosslien E
Published: January 2020

Proteins from 25 specimens of malignant breast tissue were separated by "high-resolution" two-dimensional gel electrophoresis. The number of polypeptide spots detectable in individual gels varied from 259 to 471 (mean 347; SD 68) per milligram of wet tissue. Many polypeptide spots were not consistently present in all malignant tissues. Ten different in vivo polypeptides, observed neither in five non-malignant breast tissues nor in human milk, were present in more than 22 of the 25 cases of breast tumor tissues examined. Five of these polypeptides appeared to be identical to five in vitro polypeptides found in separations from cultured human ductal carcinoma cells. Further studies are required to verify the specificity of these tumor-associated proteins before they can be considered for breast tumor-specific in vitro diagnostic testing or targeting in selective in vivo anti-cancer therapy.
Metabolic relationship between urea and guanidino compounds as studied by automated fluorimetry of guanidino compounds in urine.
Authors: Natelson S
Published: January 2020

In this automated system for assaying guanidino compounds, the compounds are resolved on an ion-exchange (Dowex 50) column, then reacted with phenanthrenequinone in alkaline solution. This mixture is then acidified and the resulting fluorescence is measured (lambda ex, 305 nm; lambda em, 395 nm). I applied the system to the analysis of urine from control rats and rats given L-canavanine, L-canavaninosuccinic acid, L-guanidinosuccinic acid, L-arginine, or urea, intraperitoneally. The recorder tracings are compared with those obtained for urine from healthy and uremic humans. After urea administration some guanidinosuccinate is excreted, along with substantial quantities of another substance that elutes just before guanidinosuccinate and so may be mistaken for it. Urine from uremic humans also shows this unidentified peak, but not urine from untreated rats or healthy humans. L-Canavanine gives rise, mainly, to guanidine and homoserine, apparently by reduction. Similarly, canavaninosuccinate is reduced to homoserine and guanidinosuccinate. Arginine gives rise to small quantities of guanidinosuccinate. Guanidinosuccinate is excreted mainly unchanged. When the guanidinosuccinate concentration is increased, excretion of guanidinoacetic acid is suppressed.
Rapid assessment of the distribution of apolipoproteins C-II and C-III subspecies in triglyceride-rich lipoproteins by isoelectric focusing.
Authors: Bugugnani M J , Koffigan M , Kora I , Ouvry D , Clavey V , Fruchart J C
Published: January 2020

We describe an isoelectric-focusing method for rapidly separating and quantifying apolipoprotein (apo) C-II and C-III subspecies of triglyceride-rich lipoproteins. Concentrated very-low-density lipoproteins (VLDL) or delipidated apo VLDL are focused on dry acrylamide plates, after their rehydration with ampholytes and urea. Apo C-II and apo C-III in VLDL are resolved into four major bands--C-II (pI 5.01), C-III0 (pI 5.10), C-III1 (pl 4.92), and C-III2 (pI 4.84)--at the same pI values as for purified apo C. This precise technique can be used without delipidating VLDL. The relative percentage of C apoproteins found in VLDL from plasma of normal subjects agreed with previously published data. The ratio of apo C-II to apo C-III decreased in patients with chronic renal failure or with coronary artery disease.
Development of an agarose gel electrophoresis technique for determining alpha-amylase isoenzymes.
Authors: Royse V L , Jensen D M
Published: January 2020

Evaluation of alpha-amylase isoenzymes as a clinical diagnostic aid by previous methodologies has been either too insensitive or too cumbersome for routine clinical laboratory use. With use of an agarose gel electrophoresis system (Worthington Diagnostic Systems, Inc.) serum amylase activity can easily be resolved into at least nine isoenzymes, the resolution being comparable with that of isoelectric focusing. Samples can be analyzed in less than one working day, with use of conventional reagents.
Limits of detection and quantification, as applied to an assay for digoxin.
Authors: Kalman S M , Clark D R , Moses L E
Published: January 2020

The low-range sensitivity of a drug assay in routine use is an important aspect of that assay's clinical usefulness. We define three concepts for determining low range sensitivity: LC, the detection threshold; LD, the lower limit of "virtually ensured" detection; and LQ, the limit of quantitative determination. To illustrate these concepts, we apply them to a radioimmunoassay for digoxin, and show that for standards ranging from 0.3 to 5.0 micrograms/L, the LQ is 0.35 micrograms/L (+/- 10%).
Inhibitor binding assay for angiotensin-converting enzyme.
Authors: Fyhrquist F , Tikkanen I , Grönhagen-Riska C , Hortling L , Hichens M
Published: January 2020

We describe a new principle for the determination of enzymes, here applied to angiotensin-converting enzyme (ACE, EC 3.4.15.1) in human serum. The enzyme inhibitor binding assay is based on specific binding of labeled inhibitor to the active center of the enzyme. Serum (10-15 microL) is incubated with 125I-labeled ACE inhibitor (" 351A ," a p- hydroxybenzamidine derivative of N-(1-carboxy-3-phenylpropyl)-L-lysyl-L-proline) at pH 7.0 at 37 degrees C for 2 h in a non-equilibrated system. Inhibitor bound to ACE is separated by adsorption to coated charcoal, the radioactivity remaining in the supernate is counted, and the ACE value is calculated from a standard curve. Sensitivity for ACE in serum is 200 U/L, corresponding to 5.0 ng of ACE purified from human lung. The coefficient of variation was 3.9% within assay, and 6.4% between assays for normal ACE activities. Correlation with a comparison spectrophotometric method (Am J Med 59: 363-372, 1975) for ACE assay was excellent (r = 0.98) in 59 samples from healthy subjects and from patients with various diseases including active sarcoidosis. The novel assay principle presented here is simple and specific, and can be extended to use with various biological fluids and tissues, and to other enzymes as well.
Radioenzymatic Assay for Direct Measurement of Plasma Pyridoxal 5'-Phosphate
Authors: Camp Vernon M , Faraj Bahjat A , Chipponi Jacques
Published: January 2020

Vol. 29

p 642: In column two, sixth line from the bottom, change "25 000" to "54 000." Insert an addition (italicized here) to the next to last line in that column so that it reads".. ., then dialyzed overnight against the same buffer at 4 °C, then divided..."

p 843: In line six under Results and Discussion, change "mg" to "µg"

p 1537: In revision of this paper a paragraph of introduction was inadvertently omitted (which cites refs. 1-5), as were the first two paragraphs under Materials and Methods, which should read as follows:

Human placentas were obtained from the obstetrical department within 12 h of delivery. Fresh human abdominal muscle was obtained within 12 h of autopsy. All tissues were stored at 4 °C and processed, as described below, within 6 h.

Placenta and abdominal muscle were stripped free of membranes and blood vessels, cut into small pieces, and extensively washed at 4 °C with cold saline (NaCl, 9 g/L). Muscle CK-MM and placental CK-BB were purified according to the method of Armstrong et al. (6), with the following modifications: we used dithioerythritol (Sigma Chemical Co., St. Louis, MO 63178), 15 mmol/L, instead of 2-mercaptoethanol, omitted the final (NH4)2SO4 precipitation and final Sephadex G-100 fractionation, and used DE-52 (Whatman Ltd., Maidstone, Kent, U.K.) instead of DEAE-cellulose (Cellex-D; Bio-Rad Laboratories, Richmond, CA 94804).

p 2026: First paragraph, lines nine and 16: delete "500" (the Dextran used in the cited reference was a 50 000-dalton preparation, not the 500 000-Da Pharmacia preparation).

p 2029: In line 10 of the first full paragraph in column two, change "1.171" to "0.117."

p 2125: First two columns and Table 1: All lipase results expressed as kU/L should be divided by 3600.

Vol. 30

p 170: The next-to-last paragraph was inadvertently omitted in layout and should read as follows:

If the sample was first incubated at 37 °C until the serum became clear (i.e., until the cryoprecipitate dissolved) and the enzyme activity immediately determined at 30 °C (Figure 2, curves 1 and 2), normal activity was observed.
Increased prostate-type acid phosphatase activity in serum and typical bone lesions simulating the presence of prostatic carcinoma.
Authors: Peters O , Gorus F , De Boeck M , Dehou M F , Van Camp B
Published: January 2020

In a man with myelomonocytic leukemia, the association of increased prostatic acid phosphatase activity in serum and the presence of typical bone lesions on roentgenography suggested the existence of disseminated prostatic carcinoma. During the clinical observation period, however, prostatic involvement could not be proved. Moreover, bone pain and prostatic-type acid phosphatase activity in serum closely paralleled monocyte counts and the degree of hepatosplenomegaly and leukemic skin lesions. Finally, meticulous postmortem examination of the prostate showed no prostatic carcinoma. This clinical picture appears to be entirely explicable in terms of leukemic organ infiltration and the proliferation of monocytes, which are known to contain acid phosphatase isoenzymes like those in the prostate.
Evaluation of the Amniostat-FLM assay for assessment of fetal lung maturity.
Authors: Lockitch G , Wittmann B K , Mura S M , Hawkley L C
Published: January 2020

Results of the "Amniostat-FLM" assay, a rapid semiquantitative test for phosphatidylglycerol, were compared with determinations of the lecithin/sphingomyelin (L/S) ratio, with phosphatidylglycerol measured by two-dimensional thin-layer chromatography, and with results of the "shake test" for 94 specimens of amniotic fluid. Correlation between results with the Amniostat and the other tests was excellent. All four tests are very accurate when predicting lung maturity. The predictive value of a negative test, i.e., that hyaline membrane disease would not occur, was between 92 and 100%. However, the accuracy of predicted lung immaturity is poor. For all four tests, predictions of lung immaturity were incorrect in more than 50% of the cases. Of the 49 infants born within 72 h of testing, none developed hyaline membrane disease when phosphatidylglycerol was detectable by either method or when the shake test indicated fetal lung maturity, but three infants with L/S ratio greater than 2/1 did develop the disease. The Amniostat provides a rapid screening method for detecting phosphatidylglycerol in amniotic fluid, which could well replace the thin-layer chromatographic method for measuring phosphatidylglycerol in the panel of diagnostic tests for fetal lung maturity.
n-Electrode three-dimensional liquid chromatography with electrochemical detection for determination of neurotransmitters.
Authors: Matson W R , Langlais P , Volicer L , Gamache P H , Bird E , Mark K A
Published: January 2020

Coulometric electrodes in series have been used with liquid chromatography with electrochemical detection to increase selectivity and resolution for the direct analysis of tissue neurotransmitters. Use of three coulometric sensors for electrochemical modification, selectivity, and peak identification has been expanded into "gate" cells of three or four coulometric electrodes that allow elimination of all electrochemically irreversible substances, and "array" cells of up to 15 coulometric electrodes for separation of co-eluting compounds by their current/voltage characteristics. On-column sensitivity of the sensor arrays is 0.4 to 4 pg. Gate cell selectivity favors electrochemically reversible compounds over irreversible ones, e.g., 3-methoxy-4-hydroxyphenylglycol vs ascorbate, by a factor of up to 10(4). Resolution across the multi-electrode array cells allows separation of co-eluting compounds with half-wave potentials differing by as little as 30 to 40 mV. Cells with three to 15 electrodes have been used to measure monoamines and metabolites in brain; monoamines directly in serum filtrate; and the state of oxidation of 5-hydroxytryptamine and 5-hydroxytryptophan in cerebrospinal fluid of patients with Alzheimer's disease.
Delta bilirubin in serum of pediatric patients: correlations with age and disease.
Authors: Brett E M , Hicks J M , Powers D M , Rand R N
Published: January 2020

At least four bilirubin fractions can be separated and identified by liquid chromatography, the least understood being the "delta" fraction (B delta), which apparently is covalently bound to albumin. To learn more about the incidence and significance of B delta, we assayed serum from 539 infants and children, both by the chromatographic method and the routine colorimetric Jendrassik-Grof method. The proportion of B delta appeared to correlate with both age and disease course. For infants younger than 28 days B delta generally was less than 2% of total bilirubin; for hyperbilirubinemic older infants and children the median B delta value was 35%. High B delta (greater than 50% of total bilirubin) in newborns was associated with intra- and extra-hepatic cholestasis, biliary cirrhosis, biliary atresia, and hepatitis. Among older infants and children, a proportion of low B delta (less than 10%) was found in hemolytic anemias, sepsis, shock, and other non-hepatic jaundice. In several cases, when low B delta was accompanied by increased conjugated bilirubin, the prognosis was very poor. Delayed clearance of B delta from the circulation together with its reactivity in direct diazo methods may interfere with interpretation of values for conjugated bilirubin as measured by classical methods.
How Brazilian congressmen connect: homophily and cohesion in voting and donation networks
Authors: Bursztyn Victor S , Nunes Marcelo G , Figueiredo Daniel R
Published: January 2020

Two fundamental activities in the career of a congressman are raising campaign funds and voting on bills. Characterizing the interplay between these two activities is crucial for democracy as it provides explicit feedback to voters on potential conflicts of interest. In this work, we investigate the Brazilian Congress to shed light on the relationships between the donations received by congressmen elected in 2014 and their voting behaviours during 2015 and 2016. By consolidating publicly available data from the House of Representatives and the Superior Electoral Court (TSE), we construct a dataset containing elected congressmen, campaign donors and donations, and legal bills and votes. This leads to the donation network (edges represent co-donation) and voting network (edges represent co-voting) in which nodes are congressmen. We examine homophily and cohesion of congressmen in these two networks with respect to their political parties and electoral regions. Our results indicate that regions exhibit stronger homophily than political parties in the donation network, while this trend is opposite for the voting network. In this sense, we find that partisan cohesion is strong and diverse in the voting network, while regional cohesion is consistently negligible. These findings are an indication of Brazil’s fragmented and weak federalist system where partisan interests override regional interests.
Proposed treatment algorithm for cardiac device-related subclavian vein stenosis: a case series
Authors: Lu Wei-Da , Chen Ju-Yi
Published: January 2020

Background

Subclavian vein obstruction may occur in patients with pacemaker leads, which may make the implantation of new pacemaker leads difficult.

Case summary

We report two cases in which upgrading to cardiac resynchronization therapy pacemaker was challenging due to total central vein occlusion. In the first case, a 78-year-old woman with permanent pacemaker implantation, 5 years ago, was successfully treated by balloon venoplasty. In the second case, balloon venoplasty was unsuccessful in a 46-year-old woman who has received twice single-chamber implantable cardioverter-defibrillator, 12 years and 5 years ago, due to vessel crowding, so a contralateral side puncture, along with a tunnel technique, was performed to solve this problem.

Discussion

Cardiac implantable electronic device-related subclavian vein stenosis can present a challenge to common cardiac resynchronization therapy device upgrades in the absence of appropriate techniques.
Pharmacologic cardioversion of recent-onset atrial fibrillation: a systematic review and network meta-analysis
Authors: deSouza Ian S , Tadrous Mina , Sexton Theresa , Benabbas Roshanak , Carmelli Guy , Sinert Richard
Published: January 2020

Aims

We sought to identify the most effective antidysrhythmic drug for pharmacologic cardioversion of recent-onset atrial fibrillation (AF).

Methods and results

We searched MEDLINE, Embase, and Web of Science from inception to March 2019, limited to human subjects and English language. We also searched for unpublished data. We limited studies to randomized controlled trials that enrolled adult patients with AF ≤ 48 h and compared antidysrhythmic agents, placebo, or control. We determined these outcomes prior to data extraction: (i) rate of conversion to sinus rhythm within 24 h, (ii) time to cardioversion to sinus rhythm, (iii) rate of significant adverse events, and (iv) rate of thromboembolism within 30 days. We extracted data according to PRISMA-NMA and appraised selected trials using the Cochrane review handbook. The systematic review initially identified 640 studies; 30 met inclusion criteria. Twenty-one trials that randomized 2785 patients provided efficacy data for the conversion rate outcome. Bayesian network meta-analysis using a random-effects model demonstrated that ranolazine + amiodarone intravenous (IV) [odds ratio (OR) 39.8, 95% credible interval (CrI) 8.3–203.1], vernakalant (OR 22.9, 95% CrI 3.7–146.3), flecainide (OR 16.9, 95% CrI 4.1–73.3), amiodarone oral (OR 10.2, 95% CrI 3.1–36.0), ibutilide (OR 7.9, 95% CrI 1.2–52.5), amiodarone IV (OR 5.4, 95% CrI 2.1–14.6), and propafenone (OR 4.1, 95% CrI 1.7–10.5) were associated with significantly increased likelihood of conversion within 24 h when compared to placebo/control. Overall quality was low, and the network exhibited inconsistency. Probabilistic analysis ranked vernakalant and flecainide high and propafenone and amiodarone IV low.

Conclusion

For pharmacologic cardioversion of recent-onset AF within 24 h, there is insufficient evidence to determine which treatment is superior. Vernakalant and flecainide may be relatively more efficacious agents. Propafenone and IV amiodarone may be relatively less efficacious. Further high-quality study is necessary.
Frailty Phenotype and Cause-Specific Mortality in the United States
Authors: Lohman Matthew C , Sonnega Amanda J , Resciniti Nicholas V , Leggett Amanda N
Published: January 2020

Background

Frailty is a common condition among older adults increasing risk of adverse outcomes including mortality; however, little is known about the incidence or risk of specific causes of death among frail individuals.

Methods

Data came from the Health and Retirement Study (HRS; 2004–2012), linked to underlying cause-of-death information from the National Death Index (NDI). Community-dwelling HRS participants aged 65 and older who completed a general health interview and physical measurements (n = 10,490) were included in analysis. Frailty was measured using phenotypic model criteria—exhaustion, low weight, low energy expenditure, slow gait, and weakness. Underlying causes of death were determined using International Classification of Diseases, Version 10 codes. We used Cox proportional hazards and competing risks regression models to calculate and compare incidence of cause-specific mortality by frailty status.

Results

During follow-up, prefrail and frail older adults had significantly greater hazard of all-cause mortality compared to individuals without symptoms (adjusted hazard ratio [HR] prefrail: 1.85, 95% CI: 1.51, 2.25; HR frail: 2.75, 95% CI: 2.14, 3.53). Frailty was associated with 2.96 (95% CI: 2.17, 4.03), 2.82 (95% CI: 2.02, 3.94), 3.48 (95% CI: 2.17, 5.59), and 2.87 (95% CI: 1.47, 5.59) times greater hazard of death from heart disease, cancer, respiratory illness, and dementia, respectively.

Conclusions

Significantly greater risk of mortality from several different causes should be considered alongside the potential costs of screening and intervention for frailty in subspecialty and general geriatric clinical practice. Findings may help investigators estimate the potential impact of frailty reduction approaches on mortality.
Cell-to-Cell Variation in Gene Expression for Cultured Human Cells Is Controlled in Trans by Diverse Genes: Implications for the Pathobiology of Aging
Authors: Zhang Jiaming , Burnaevskiy Nikolay , Annis James , Han Wenyan , Hou Deyin , Ladd Paula , Lee Lin , Mendenhall Alexander R , Oshima Junko , Martin George M
Published: January 2020

Cell-to-cell variation in gene expression increases among homologous cells within multiple tissues during aging. We call this phenomenon variegated gene expression (VGE). Long, healthy life requires robust and coordinated gene expression. We posit that nature may have evolved VGE as a bet-hedging mechanism to protect reproductively active populations. The price we may pay is accelerated aging. That hypothesis will require the demonstration that genetic loci are capable of modulating degrees of VGE. While loci controlling VGE in yeast and genes controlling interindividual variation in gene expression in Caenorhabditis elegans have been identified, there has been no compelling evidence for the role of specific genetic loci in modulations of VGE of specific targets in humans. With the assistance of a core facility, we used a customized library of siRNA constructs to screen 1,195 human genes to identify loci contributing to the control of VGE of a gene with relevance to the biology of aging. We identified approximately 50 loci controlling VGE of the prolongevity gene, SIRT1. Because of its partial homology to FOXO3A, a variant of which is enriched in centenarians, our laboratory independently confirmed that the knockdown of FOXF2 greatly diminished VGE of SIRT1 but had little impact upon the VGE of WRN. While the role of these VGE-altering genes on aging in vivo remains to be determined, we hypothesize that some of these genes can be targeted to increase functionality during aging.