bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of carbamylated hemoglobin by high-performance liquid chromatography
Authors: Kwan J T , Carr E C , Bending M R , Barron J L 
Published: January 2020

Abstract
We have developed an HPLC method for measuring carbamylated hemoglobin (CarHb), based on the quantification of valine hydantoin formed from the released NH2-terminal carbamyl valine residue after acid hydrolysis of hemoglobin. In uremia, CarHb is produced by nonenzymatic post-translational modification of the terminal amino group of hemoglobin monomers by isocyanic acid, derived from the spontaneous dissociation of urea. We measured CarHb in 25 nonuremic control subjects, 24 nonuremic diabetic subjects, and 30 patients with stable chronic renal failure. There was no significant difference between the controls and diabetic patients, their mean (SD) CarHb values being 41 (11.5) and 38 (10.8) micrograms of carbamyl valine per gram of hemoglobin (microgram CV/gHb), respectively. Mean (SD) CarHb values in the uremic patients were much greater, 164 (87.7) microgram CV/gHb. There was significant correlation between the concentrations of CarHb and plasma urea in the uremic subjects. Thus CarHb provides a urea-derived index of chronic uremia.
Measuring free thyroxin by using magnetic antibody-containing microcapsules
Authors: Wallace A M , Aitken S , Duffy F A , Fraser W D , Beastall G H 
Published: January 2020

Abstract
We describe a novel magnetic-separation microencapsulated antibody displacement assay for free thyroxin. The method is rapid (results available in just over an hour), with a detection limit of 3 pmol/L, and an interassay precision of less than 10% over the range 8-75 pmol/L. Results are not influenced by changes in the concentration of thyroxin-binding globulin or albumin, nor by the presence of circulating anti-thyroxin antibodies or physiological concentrations of nonesterified (free) fatty acids. A reference interval of 8.4-18.4 pmol/L was established for a large euthyroid adult population. Patients with various nonthyroidal illnesses exhibited a similar reference interval (6.2-17.4 pmol/L). Results from pregnant women, at all stages of gestation, were within the nonpregnant euthyroid reference interval. Complete discrimination was obtained between the euthyroid reference interval and values from patients with untreated thyrotoxicosis (24-75 pmol/L). Excellent, though incomplete, discrimination was obtained for patients with untreated hypothyroidism (less than 3.0-9.0 pmol/L). Results for a group of patients defined as having compensated euthyroidism (5.0-15 pmol/L) showed considerable overlap with the euthyroid reference interval. Patients taking thyroxin, who were clinically euthyroid and whose serum concentration of thyrotropin was within its euthyroid reference interval, had free thyroxin concentrations in the range 13.4-24.2 pmol/L. We discuss the validity of this assay in clinical practice.
Effects of 3-deoxyglucosone on the Maillard reaction
Authors: Igaki N , Sakai M , Hata H , Oimomi M , Baba S , Kato H 
Published: January 2020

Abstract
We investigated the effect of exogenously applied 3-deoxyglucosone, a major carbonyl intermediate, on the Maillard reaction. The fluorescence intensity of the product of the reaction of bovine serum albumin with 3-deoxyglucosone was higher than that with an equivalent amount of glucose. Similarly the rate of polymerization of lysozyme in the presence of 3-deoxyglucosone was also greater than with glucose, and collagen incubated with 3-deoxyglucosone was less digestible than collagen incubated with glucose. By contrast, aminoguanidine inhibited an increase in fluorescence of the Maillard compounds and the polymerization of protein, both of which were stimulated by 3-deoxyglucosone. These results suggest that 3-deoxyglucosone accelerates the advanced stage of the Maillard reaction and that aminoguanidine acts on 3-deoxyglucosone to inhibit its action in the advanced stage of the Maillard reaction.
Specificities compared for a radioreceptor assay and a radioimmunoassay of atrial natriuretic peptide
Authors: Capper S J , Smith S W , Spensley C A , Whateley J G 
Published: January 2020

Abstract
The main active form of atrial natriuretic peptide (ANP) in the circulation is alpha ANP(1-28) [gamma-ANP(99-126)], although some active and inactive metabolites are also though to be present. Some immunoassays for alpha ANP reportedly detect inactive metabolites, as determined by their comparison with results by receptor assay, which would lead to misleading results for alpha ANP(1-28) measurements. Here we compare a radioreceptor assay (RRA) and a radioimmunoassay (RIA) for alpha ANP and show that their results correlate very well with regard to specificity and that the RIA appears to detect only the active circulating form of alpha ANP(1-28).
Improved method of analysis for aluminum in brain tissue
Authors: van Ginkel M F , van der Voet G B , de Wolff F A 
Published: January 2020

Abstract
To improve the accuracy and precision of the assay of aluminum in brain tissue, we modified for application to brain samples from rats and humans the wet-digestion method of Trapp et al. (Biol Psychiatry 1978; 13:709-18), established the contribution of contamination, and examined the effect of precipitation of nonoxidizable fatty residues on the analysis. Specifications of the modified assay are a detection limit of 5 ng of aluminum per gram wet weight of brain tissue, a within-day CV of 4.8% (24.3 microgram/L; n = 10), and a day-to-day CV of 5.5% (27.8 micrograms/L; n = 5). Contamination, a systematic error in the analysis of aluminum, was established to be 13 ng (SD = 7.9 ng; n = 8) per tube. The presence of indestructible fatty residues did not affect the accuracy of the method. Application of the method to brain hemispheres of nonexposed rats revealed an aluminum content of 0.041 mg/kg wet weight of tissue (SD = 0.032 mg/kg; n = 8). The aluminum content in human cortex samples, consisting of gray and white matter, ranged from 0.14 to 0.22 mg/kg. Modification of the wet-digestion method resulted in a reliable, simple sample pretreatment before analysis for aluminum in brain tissue. The extent of the aluminum contamination must be controlled by including appropriate blanks.
Polyclonal antibody-based enzyme-linked immunosorbent assay of alpha 1-acid glycoprotein
Authors: Tissot B , Seta N , Durand G , Feger J 
Published: January 2020

Abstract
This is a noncompetitive enzyme-linked immunosorbent assay for measuring low concentrations (2 to 100 micrograms/L) of human alpha 1-acid glycoprotein (AGP; orosomucoid). The method is based on a simple "sandwich" technique involving polyclonal rabbit antisera against AGP. Mean within-run and total (between-run) CVs were 6.2% and 9.7%, respectively. Analytical recovery, tested in various biological fluids, averaged 101%. The technique has been successfully applied to diluted biological fluids such as bronchoalveolar lavage, cerebrospinal and amniotic fluids, and hepatocyte-culture supernates. Because of its analytical validity and the commercial availability of the reagents, this assay is suitable for large-scale determinations of AGP concentrations in those biological fluids in which its concentration is relatively low.
Use of free and transthyretin-bound retinol-binding protein in serum as tests of vitamin A status in humans: effect of high creatinine concentrations in serum
Authors: Burri B J , Bankson D D , Neidlinger T R 
Published: January 2020

Abstract
We measured immunologically active (apo + holo) retinol-binding protein (RBP), vitamin A-carrying (holo) free RBP, and transthyretin-bound (TTR) holo-RBP in serum from 34 retrospective cases of fluctuating acute renal failure. All subjects had high serum creatinine concentrations caused by renal failure. Apo + holo, holo-TTR-RBP, and (especially) holo-free RBP all correlated poorly but significantly with serum creatinine concentration. Therefore, the use of any form of RBP to measure vitamin A status may be of limited value in subjects with high creatinine concentrations in serum. However, molecular-exclusion HPLC may be able to distinguish increases in RBP concentration associated with renal failure from those caused by altered vitamin A status, because renal failure causes abnormalities in the number and retention times of chromatographic peaks as well as their areas.
New automated measurement of mitochondrial aspartate aminotransferase with use of protease 401
Authors: Watazu Y , Uji Y , Sugiuchi H , Okabe H , Murao S 
Published: January 2020

Abstract
Total mitochondrial aspartate aminotransferase (EC 2.6.1.1), the sum of apo- and holo-mitochondrial aspartate aminotransferase activity in human serum, was measured by using a proteolytic method: inactivation of cytosolic aspartate aminotransferase with cytosolic aspartate aminotransferase-inactivating protease 401 from Streptomyces violaceochromogenes. Cytosolic aspartate aminotransferase is completely inactivated, and apo-mitochondrial aspartate aminotransferase is completely activated by pyridoxal 5'-phosphate within 5 min. Results by the proposed method correlated well with those by an immunochemical method (r = 0.994, n = 145) and showed excellent inhibitory activity of the protease for holo- and apo-cytosolic aspartate aminotransferase up to 5000 U/L and activation of mitochondrial apo-aspartate aminotransferase up to 2000 U/L in the presence of 100 mumol of pyridoxal 5'-phosphate per liter. Within-run Cvs were good (1.13-7.49%). Mean values for total mitochondrial aspartate aminotransferase and apo-mitochondrial aspartate aminotransferase activities in serum of the healthy subjects were 4.8 (SD 0.9) and 1.8 (SD 0.8) U/L, respectively (n = 154). Various common interferents tested did not affect this assay.
Invalidity of hand heating as a method to arterialize venous blood
Authors: Green J H , Ellis F R , Shallcross T M , Bramley P N 
Published: January 2020

Abstract
We have assessed in normal subjects the validity of using hand heating to obtain "arterialized" venous blood by biochemical comparison of results for "arterialized" venous and true arterial (radial artery) blood samples. The heating regimen involved placing one hand in an air-heated box at 45-50 degrees C for 45 min. This method produced blood that was "arterialized" for lactate, PCO2, HbO2, and Hb but not for ammonia or PO2; it had no effect on determinations of pyruvate or glucose in plasma. Despite using a lower air temperature than previous workers, we observed thermal injury in one volunteer. Further, there was considerable between-subject variation in the effect of hand heating on blood gases. This suggests that blood gases should be measured in the "arterialized" samples at regular intervals from the start of hand heating in each patient to determine whether maximal "arterialization" has been achieved, to avoid making misleading biochemical measurements. Given the wide range in degree of observed "arterialization," we question the validity of this method.
Optimized preservation of isoforms of creatine kinase MM isoenzyme in plasma specimens and their rapid quantification by semi-automated chromatofocusing
Authors: Abendschein D R , Fontanet H L , Nohara R 
Published: January 2020

Abstract
We report a convenient chromatofocusing procedure for rapid and sensitive quantification of isoforms of the MM isoenzyme of creatine kinase (EC 2.7.3.2) in plasma and efficient methods for preserving isoform profiles during handling of specimens. The assay involves use of prepacked, re-usable Mono P chromatofocusing columns and a "Fast Protein Liquid Chromatograph" (FPLC) system with on-line detection of isoform enzymatic activity in column effluent. Profiles of isoforms are analyzed within 25 min with the use of a 1-mL column; the lower limit of sensitivity for CK activity is 5 mU, and recovery of each isoform is within 1% of the amount added to plasma. Collection of blood specimens in Vacutainer Tubes containing 28.5 mumol of EDTA (final concentration in plasma, 7 to 10 mmol/L) inhibited carboxypeptidase activity in plasma by 76%, sufficient to essentially abolish isoform conversion in vitro at room temperature. These methods should facilitate applications of isoform analysis for diagnosis of myocardial infarction and coronary artery recanalization.
Radial "high-performance" thin-layer chromatography used to assess fetal lung maturity
Authors: Mackenzie J R , Truesdale M 
Published: January 2020

Abstract
A radial "high-performance" thin-layer chromatographic (HPTLC) method is described by which the percentages and ratios of phosphatidylinositol, sphingomyelin, lecithin, phosphatidylethanolamine, phosphatidylglycerol, and dimethyl phosphatidylethanolamine may be determined simultaneously. An additional method for radial HPTLC determination of saturated phosphatidylcholine is described. We report results of application of these methods to greater than 2000 specimens of amniotic fluid from both diabetic and nondiabetic cases.
Variations in abundance of the molecular ion of the derivatized cocaine metabolite benzoylecgonine
Authors: Bodor G , Roggeman R , Turk J 
Published: January 2020

Abstract
Benzoylecgonine (BEG) is the principal urinary metabolite of cocaine. For forensic drug testing, the presence of BEG in urine, suggested by a positive result for a screening immunoassay, must be confirmed by quantitative gas chromatographic/mass spectrometric (GC/MS) analysis, i.e., stable isotope dilution with a deuterium-labeled internal standard. GC/MS criteria for positivity also require appropriate relative abundances of qualifier ions, including the molecular ion, but there is little published information on the observed absolute values for qualifier ion ratios or on the variability of these values. This lack of information creates uncertainty for laboratories initiating programs testing urine for drugs of abuse as to performance criteria for run acceptability and sample positivity. We have observed substantial variability (CV = 50%) in the abundance of the molecular ion of derivatized BEG relative to the base ion in reference materials. This variability can result in a high rate of repetition of runs and generate confusion in the defense of forensic drug-testing results. Normalization of the abundance of the molecular ion of derivatized BEG to that of the deuterium-labeled internal standard in the same sample greatly reduces the apparent variability in this measurement; it is also more reliable than the absolute value of the relative abundance of the molecular ion in determining run acceptability and positive or negative results for a sample.
Rapid and simultaneous determination of lactulose and mannitol in urine, by HPLC with pulsed amperometric detection, for use in studies of intestinal permeability
Authors: Fleming S C , Kapembwa M S , Laker M F , Levin G E , Griffin G E 
Published: January 2020

Abstract
The lactulose/mannitol dual sugar absorption test is a non-invasive test of intestinal permeability. Its widespread use has been limited by the difficulties of analysis for carbohydrates in urine at low concentrations. We describe a "high-pressure" liquid-chromatographic method for determining lactulose and mannitol in urine, in which anion-exchange chromatography and pulsed amperometric detection are used. Sample preparation is simple and fast, and lactulose and mannitol and the internal standards arabinose and cellobiose are well resolved within 15 min. Analytical response of the method is linear with concentrations to 3 g/L, and one can detect as little as 0.3 mg of lactulose per liter of urine. Analytical recovery was between 90% and 107% for all sugars analyzed, and there was good agreement with results by a gas-chromatographic method (r = 0.993 lactulose, 0.984 mannitol). The method may potentially be applied to the study of other carbohydrates present in biological fluids at low concentrations.
New ultrafiltration method for free thyroxin compared with equilibrium dialysis in patients with thyroid dysfunction and nonthyroidal illness
Authors: Tikanoja S H , Liewendahl B K 
Published: January 2020

Abstract
This new ultrafiltration method for free thyroxin in serum [FT4(U)] is based on radioimmunoassay of the free hormone fraction in ultrafiltrates obtained by centrifuging serum samples in Unisep Ultracent-10 ultrafiltration devices. We compared the results obtained with those by an equilibrium dialysis method [FT4(D)]. In 36 euthyroid healthy subjects, the mean FT4(U) concentration was 24.2 pmol/L and the mean FT4(D) concentration 14.8 pmol/L. In hyperthyroid and hypothyroid patients, results by the ultrafiltration method were also approximately twice as high as those obtained by the dialysis method. In 23 patients with various nonthyroidal illnesses, mean FT4(U) was 41.2 pmol/L and mean FT4(D) 19.8 pmol/L. The mean FT4(U)/FT4(D) ratio in patients with nonthyroidal illnesses (1.97) was not significantly higher than in control subjects (1.68), making it unlikely that the increase in serum FT4 is caused by weakly protein-bound and therefore dialyzable inhibitors of thyroxin binding to carrier proteins. However, two nonthyroidally ill patients with a clearly increased FT4(U) but a normal FT4(D) concentration might have had such inhibitors, whereas for two other nonthyroidally ill patients a high molar ratio of free fatty acids to albumin is a more likely explanation for increased FT4(U) and FT4(D) concentrations. On theoretical grounds, we consider the FT4(U) concentrations analytically more nearly accurate than FT4(D) values for all patient groups studied.
Therapeutic monitoring of cyclosporine: impact of a change in standards on 125I-monoclonal RIA performance in comparison with liquid chromatography
Authors: Keown P A , Glenn J , Denegri J , Maciejewska U , Seccombe D , Stawecki M , Freeman D , Stiller C , Shackleton C , Cameron E 
Published: January 2020

Abstract
This study examines the measurement of cyclosporine (CsA) by 125I-monoclonal RIA, and describes the impact of the recent change in the standard curve provided. CsA concentrations in serum and whole-blood control samples measured by 125I-RIA were initially 8-18% higher than those by HPLC. During the first two months of 1989, a significant and sustained deviation in the 125I-RIA produced results that exceeded the HPLC results by 21-28% (P less than 0.001). Introduction of the new standard curve in March 1989 returned the concentration of the whole-blood controls to the previous range (11-12% above HPLC, P less than 0.001). Measurement of clinical samples from heart, liver, and bone-marrow graft recipients by 125I-RIA by both old and new kit standards produced a close linear correlation (y = 0.89 x - 19.02; r = 0.99; n = 75, range = 40-850 micrograms/L), with use of the new standards yielding results 82 (SD 8)% of those with the preceding assay. However, even with the new standard curve, CsA concentrations by 125I-RIA in the clinical samples exceeded those by HPLC by a factor of 1.37 (SD 0.18) to 1.52 (SD 0.19). Segregation for transplant type did not affect the RIA/HPLC ratio. The results suggest cross-reactivity of the 125I-RIA with material present in vivo.
Benzalkonium interference with test methods for potassium and sodium
Authors: Koch T R , Cook J D 
Published: January 2020

Abstract
Six automated instruments that measure sodium and potassium were tested for interference from two compounds used in catheters. Tridodecylmethylammonium heparin did not interfere with any of the methods. However, benzalkonium heparin falsely increased sodium measurement with the Kodak Ektachem, and falsely increased potassium measurements with three instruments (Beckman Astra, Baxter Paramax, and the Instrumentation Laboratory Monarch) in which ion-selective electrodes measure potassium in diluted serum. Three instruments in which ion-selective electrodes measure serum directly--Du Pont Dimension, Abbott Spectrum, and Kodak Ektachem--experienced no interference with potassium measurements. Interference of benzalkonium with potassium measurements may result from its interaction with the electrode membranes, which is accentuated in diluted serum.
Transient hyperglycemia during abdominal aortic surgery
Authors: Ellison D A , Forman D T 
Published: January 2020

Abstract
A 64-year-old man undergoing abdominal aortic aneurysm repair with no history of diabetes mellitus had an episode of marked hyperglycemia during surgery. The peak concentration of glucose in plasma was 43.2 mmol/L. This hyperglycemia responded immediately to administration of 30 units of regular insulin. Factors involved in the hyperglycemia included surgical stress, multiple medications, and the anesthetic used (isoflurane), but do not fully account for the magnitude of the increase in glucose. The data suggest that the patient may have had an underlying insulin deficiency, which was unmasked by the stress of surgery.
Determination of creatinine in serum and urine by a rapid liquid-chromatographic method
Authors: Paroni R , Arcelloni C , Fermo I , Bonini P A 
Published: January 2020

Abstract
We describe an HPLC ion-pair procedure for rapid and specific evaluation of creatinine in serum and urine. We used a 15 cm X 4.6 mm ODS column with a 50/50 (by vol) mixture of sodium decanesulfonic acid (10 mmol/L, pH 3.2) and methanol and measured absorbance at 236 nm. Serum (100 microL) or 30-fold-diluted urine (100 microL) was added to 400 microL of acetone. After centrifugation, the supernates (300 microL) were dried, reconstituted with the mobile phase, and injected into the HPLC. Assay precision was tested for concentrations of 10, 29, and 130 mg/L and yielded, respectively, 3.1%, 2.1%, and 1.1% for within-day CV and 2.8%, 2.1%, and 2.2% for total CV. Analytical recovery was 102 (+/- 6.7%). Linearity was demonstrated in the 0-200 mg/L range for serum and 0-3.5 g/L range for urine (r greater than or equal to 0.999). The detection limit for creatinine (signal-to-noise ratio = 3) was 0.5 mg/L. We used cimetidine for internal standardization. Correlation was good between this procedure and the Jaffé kinetic, the enzymatic (creatinine amidohydrolase), and the Fuller's earth alkaline picrate methods.
Ultrafiltrable copper and related analytes in maternal and cord blood
Authors: Noubah A M , al-Awqati M A 
Published: January 2020

Abstract
We utilized the Amicon micropartition system (MPS-1) to prepare ultrafiltrates of serum for evaluating non-protein-bound copper (NPBCu). The method is rapid (a usual turnaround time less than 2 h), practical (only 1 mL of serum is required), and reproducible (average CV = 5.7% within assay and 9.3% between assays). Using this technique, we determined that (a) NPBCu in serum appeared to be fairly stable, showing little variation among subjects in different physiological conditions (normal female, pregnancy, or fetal samples); and (b) of all copper fractions studied, only NPBCu appeared to correlate between maternal concentrations and cord counterparts at delivery. Thus the NPBCu fraction may be appreciably involved in the overall mechanism of copper nutritional supply from mother to fetus.