bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of total mercury in biological specimens by cold vapor atomic fluorescence spectrometry
Authors: Winfield S A , Boyd N D , Vimy M J , Lorscheider F L 
Published: January 2020

Abstract
An ultrasensitive method for determining total mercury concentrations in biological specimens is a prerequisite for monitoring exposure to chronic low-dose levels of Hg vapor such as those from dental silver amalgam fillings. The clinical consequences of such doses are currently in question. We describe an adaptation of a two-stage gold amalgamation preconcentration step combined with cold vapor atomic fluorescence spectrometric detection for Hg. At Hg concentrations of 40 and 350 nmol/L, the within-day assay CVs were 5% and 3%, respectively; between-day assay CVs were 8% and 5%, respectively. Accuracy, as demonstrated by analytical recovery, ranged from 98% to 105%. The detection limit for the assay is 50 pmol/L, which is suitable for measuring total Hg concentrations in specimens of human urine, blood, and breast milk, and in monkey kidney cortex and feces, obtained from subjects with and without amalgam fillings.
Modification of the dextran-Mg2+ high-density lipoprotein cholesterol precipitation method for use with previously frozen plasma
Authors: McNamara J R , Huang C , Massov T , Leary E T , Warnick G R , Rubins H B , Robins S J , Schaefer E J 
Published: January 2020

Abstract
Although dextran-Mg2+ precipitation produces accurate and precise results for high-density lipoprotein (HDL) cholesterol in fresh plasma and serum, precipitation of frozen specimens with triglycerides &gt; 2.26 mmol/L (&gt; 200 mg/dL) is difficult. We developed a modification that dilutes thawed samples by 35% and increases dextran-Mg2+ reagent to 15% of sample volume. Standard precipitations were performed on 62 fresh EDTA-treated plasma specimens; supernatant solutions were analyzed fresh and after freezing. Standard and modified methods were also performed on thawed, paired plasmas. In specimens with triglycerides &lt; or = 2.26 mmol/L, HDL cholesterol results for all methods were similar. For triglycerides &gt; 2.26 mmol/L, however, bias and precision were significantly affected by freezing, and 38.5% of samples with standard precipitation required additional procedures to produce clear supernatant solutions. HDL cholesterol concentrations for thawed samples with standard precipitation were significantly greater than for fresh samples (P &lt; 0.02), but those for the modified method were not different from fresh samples, and only one specimen required additional steps to produce a clear supernate.
Distribution of CII and CIII peptides in lipoprotein classes: methods and clinical significance
Authors: Graziani M S , Zanolla L , Righetti G , Marchetti C , Zanotto G , Lupo A 
Published: January 2020

Abstract
We describe a method for measuring apolipoprotein (apo) C distribution between apo B-containing lipoprotein (apo B-LP) and non-apo B-LP. The procedure requires the precipitation of apo B-LP, the redissolution of the pellet, and the quantification of C peptides in the redissolved pellet. The ratio of apo C in non-apo B-LP to apo C in apo B-LP has been calculated for both CII and CII (R-CII and R-CIII, respectively). R-CII (0.49 +/- 0.25) and R-CIII (0.84 +/- 0.54) in patients on maintenance dialysis are significantly lower than in the control group (1.14 +/- 0.57 and 1.45 +/- 0.92, respectively), indicating that hypertriglyceridemia in these patients results from a reduced catabolism of triglyceride-rich LP (TGRLP). Patients with coronary artery disease (CAD) show a distribution of C peptides no different from the control group. Analysis of covariance reveals that the patterns of R-CII and R-CIII are not entirely predictable from the serum concentration of triglycerides. This result seems to support the hypothesis that the underlying metabolic defects involving TGRLP in dialysis patients are not the same as those in patients with CAD.
Role of serotonin in the pathophysiology of depression: focus on the serotonin transporter
Authors: Owens M J , Nemeroff C B 
Published: January 2020

Abstract
Considerable evidence has accrued in the last two decades to support the hypothesis that alterations in serotonergic neuronal function in the central nervous system occur in patients with major depression. These findings include the following: (a) reduced cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of serotonin (5-HT) in drug-free depressed patients; (b) reduced concentrations of 5-HT and 5-HIAA in postmortem brain tissue of depressed and (or) suicidal patients; (c) decreased plasma tryptophan concentrations in depressed patients and a profound relapse in remitted depressed patients who have responded to a serotonergic antidepressant when brain tryptophan availability is reduced; (d) in general, all clinically efficacious antidepressants augment 5-HT neurotransmission following chronic treatment; (e) clinically efficacious antidepressant action by all inhibitors of 5-HT uptake; (f) increases in the density of 5-HT2 binding sites in postmortem brain tissue of depressed patients and suicide victims, as well as in platelets of drug-free depressed patients; (g) decreased number of 5-HT transporter (determined with [3H]imipramine or [3H]paroxetine) binding sites in postmortem brain tissue of suicide victims and depressed patients and in platelets of drug-free depressed patients. In our studies, this reduction in platelet 5-HT transporter binding is not due to prior antidepressant treatment of hypercortisolemia and is not observed in mania, Alzheimer disease, schizophrenia, panic disorder, fibromyalgia, or atypical depression. In a pilot study, this deficit predicted treatment response to an experimental antidepressant. These findings support the hypothesis that alterations in 5-HT neurons play a role in the pathophysiology of depression.
Plasma concentrations of gamma-aminobutyric acid (GABA) and mood disorders: a blood test for manic depressive disease?
Authors: Petty F 
Published: January 2020

Abstract
gamma-Aminobutyric acid (GABA), an inhibitory neurotransmitter that serves about one-third of brain neurons, is involved in the development of depression and in the treatment of depression and mania with pharmacological therapy. Brain activity of GABA may be conveniently measured in plasma, and changes in plasma concentrations of GABA reflect brain GABA activity. Plasma concentrations of GABA are significantly lower than control values in about one-third of patients with major depressive disorder; concentrations are also low in patients with mania and in bipolar patients who are depressed. These low concentrations of GABA appear to persist after recovery from depression and are not increased by treatments that improve depressive symptoms. Follow-up studies suggest that GABA concentrations remain relatively constant over at least 4 years. Additionally, preliminary data suggest that low plasma GABA is a familial marker of mood disorders in a subset of patients. Despite the difficulty of demonstrating that a particular biochemical measure is a true genetic trait marker for vulnerability for development of an illness, the accumulated data suggest that low plasma GABA may represent a biological marker of vulnerability for development of various mood disorders.
Brain mechanisms in manic depression
Authors: Carroll B J 
Published: January 2020

Abstract
Manic depressive illness (bipolar disorder) is the mood disorder classically considered to have a strong biological basis. During manic depressive cycles, patients show dramatic fluctuations of mood, energy, activity, information processing, and behaviors. Theories of brain function and mood disorders must deal with the case of bipolar disorder, not simply unipolar depression. Shifts in the nosologic concepts of how manic depression is related to other mood disorders are discussed in this overview, and the renewed adoption of the Kraepelinian "spectrum" concept is recommended. The variable clinical presentations of manic depressive illness are emphasized. New genetic mechanisms that must be considered as candidate factors in relation to this phenotypic heterogeneity are discussed. Finally, the correlation of clinical symptom clusters with brain systems is considered in the context of a three-component model of manic depression.
Quantification of lipoprotein(a) in plasma by assaying cholesterol in lectin-bound plasma fraction
Authors: Seman L J , Jenner J L , McNamara J R , Schaefer E J 
Published: January 2020

Abstract
Lipoprotein(a) [Lp(a)] is a low-density lipoprotein (LDL)-like particle in which apolipoprotein(a) [apo(a)] is disulfide-linked to apolipoprotein B (apoB). High concentrations of Lp(a) in plasma are associated with an increased risk of coronary heart disease (CHD). Lp(a) has traditionally been measured by immunoassay and expressed as total mass of Lp(a). Measuring Lp(a) by its cholesterol content will provide a way to directly compare Lp(a) with other lipoproteins that are measured by cholesterol. We have developed an assay to quantify Lp(a) by its cholesterol content [Lp(a)-C], using lectin affinity to isolate Lp(a) from other lipoproteins, and then measuring the cholesterol within the isolated fraction. We compared the Lp(a)-C assay with an ELISA for Lp(a) mass in 47 plasma samples from normotriglyceridemic, fasting individuals with high Lp(a) contents (mean +/- SD, 446 +/- 350 mg/L). The mean Lp(a)-C concentration was 110 +/- 89 mg/L and correlated very highly with Lp(a) mass (r = 0.9975). Lp(a)-C measurement is an alternative method to screen for this CHD risk factor.
Demonstration and minimization of serum interference in flow cytometric two-site immunoassays
Authors: Frengen J , Kierulf B , Schmid R , Lindmo T , Nustad K 
Published: January 2020

Abstract
The ability of serum factors to cross-link labeled mouse monoclonal antibody (mAb) of irrelevant specificity (mAb FN61, subclass IgG1) to different particle types coated with sheep IgG, bovine gamma-globulin, or mAb FN61 was measured simultaneously by flow cytometry. Significant interference with mAb FN61-coated particles was detected in 53 of 101 sera. Of the 30 sera showing the most pronounced interference, 23 were characterized by an even stronger cross-linking to particles coated with bovine gamma-globulin. These were designated type 1 sera. Seven sera, designated type 2, displayed a dominant interference with the mAb FN61-coated particles. The interference reaction in the two serum types was characterized by different kinetics, dependence on particle concentration, and response to blocking agents. The interference was minimized by addition of 500 micrograms of bovine gamma-globulin and 50 micrograms of mAb HH1 (IgG1) of irrelevant specificity per 10 microL of serum sample in a final assay volume of 100 microL.
Plasma homocyst(e)ine as a risk factor for early familial coronary artery disease
Authors: Wu L L , Wu J , Hunt S C , James B C , Vincent G M , Williams R R , Hopkins P N 
Published: January 2020

Abstract
We measured plasma homocyst(e)ine [H(e)] and other coronary risk factors in 266 patients with early coronary artery disease from 170 families in which two or more siblings were affected and in 168 unmatched controls. The mean H(e) concentration adjusted for significant correlates (serum creatinine, uric acid, and low-density lipoprotein cholesterol) was 12.0 mumol/L in proband cases compared with 10.1 mumol/L in controls (P = 0.0001). Many (17.6%) of the proband cases had H(e) concentrations exceeding the 95th percentile for the controls (relative odds = 4.9, P &lt; 0.001). H(e) among cases was bimodally distributed even after adjustment for concentrations of plasma vitamins. Concordant high H(e) was seen in at least 10 (12%) of 85 families with two or more affected siblings. We conclude that a substantial proportion of early familial coronary artery disease is probably related to production of high concentrations of H(e) by one or more major genes.
International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B. IV. Comparability of apolipoprotein B values by use of International Reference Material
Authors: Marcovina S M , Albers J J , Kennedy H , Mei J V , Henderson L O , Hannon W H 
Published: January 2020

Abstract
We performed temporal and thermal stability studies on SP3-07, a liquid-stabilized reference material for apolipoprotein (apo) B, selected during the previous phase of the International Federation of Clinical Chemistry project on standardization of apolipoprotein measurements. Results indicate that SP3-07 stored at -70 degrees C has the long-term stability required for a reference material. We assigned an accuracy-based apo B value of 1.22 g/L to SP3-07, using a nephelometric method that was calibrated with freshly isolated low-density lipoprotein for which the apo B mass value was determined by a standardized sodium dodecyl sulfate-Lowry procedure. Using a common protocol, the study participants transferred the assigned mass value from SP3-07 to the individual calibrators of the analytical systems and measured the apo B concentration of 20 fresh-frozen samples obtained from individual donors and covering a clinically relevant range of apo B values. The among-laboratory CV on these samples, analyzed by 25 analytical systems, ranged from 3.1% to 6.7%. These results demonstrate the lack of matrix effects of SP3-07 and its ability to provide accurate and comparable apo B values in a variety of immunochemical methods. On the basis of the outcome of these studies, the World Health Organization has endorsed SP3-07 as the International Reference Material for Apolipoprotein B.
Method-dependent variations in the stability of apolipoprotein B in a stabilized liquid reference material
Authors: Mei J V , Powell M K , Henderson L O , Smith S J , Cooper G R , Marcovina S M , Hannon W H 
Published: January 2020

Abstract
Using accelerated Arrhenius-type short-term and long-term temporal studies, we evaluated the storage life of a stabilized, liquid-frozen reference material (SLRM) for human apolipoprotein B (apo B) developed by the International Federation of Clinical Chemistry. As measured by our candidate reference RIA, the concentrations of immunoreactive apo B in the SLRM showed pronounced degradation with exposure to increasing temperatures over time. The SLRM was stable for as long as 1 year when stored at - 70 degrees C, but its immunoreactive apo B declined by &lt; 10% when stored at 4 degrees C for 10 months. Using radial immunodiffusion and an ELISA to assess the equivalency of measured mass for the accelerated thermal stability of the SLRM, we found a loss of immunoreactive apo B similar to that measured by RIA. Analyzing the same samples by liquid immunoprecipitation (nephelometry) resulted in the amount of apo B present being overestimated, especially in samples held for long periods. By using different immunological methods to evaluate this thermally aged SLRM, we demonstrated that its measured behavior varies depending on the method of quantitation.
15-Desmethyl FK-506 and 15,31-desmethyl FK-506 from human liver microsomes: isolation, identification (by fast atom bombardment mass spectrometry and NMR), and evaluation of in vitro immunosuppressive activity
Authors: Lhöest G J , Maton N , Latinne D , Laurent A , Verbeeck R K 
Published: January 2020

Abstract
15-Desmethyl FK-506 and 15,31-desmethyl FK-506 metabolites extracted from incubated human liver microsomes were separated by normal and reversed-phase HPLC. The metabolites were identified by fast atom bombardment/mass spectrometry and nuclear magnetic resonance spectroscopy. The in vitro 50% inhibitory concentration, tested against bidirectional mixed lymphocyte reactions, was 325 mg/L for 15,31-desmethyl FK-506 and 4 mg/L for 15-desmethyl FK-506, indicating that these products of FK-506 demethylation retain in vitro immunosuppressive activity.
Time-resolved immunofluorometric assay and specimen storage conditions for measuring urinary gonadotropins
Authors: Saketos M , Sharma N , Adel T , Raghuwanshi M , Santoro N 
Published: January 2020

Abstract
We optimized storage conditions and validated a sensitive immunofluorometric assay (IFMA) for urinary gonadotropins. Assay linearity and parallelism for luteinizing hormone (LH) and follicle-stimulating hormone (FSH) was observed to 0.04 IU/L. Urinary LH and FSH were unaffected by changes of osmolarity from 0.5 to 3.0 mOsm/kg, and from pH 4.5 to 10.5. Serum and urine measurements of the hormones correlated well over a wide range of values: for LH, R2 = 0.94, P &lt; 0.01; for FSH, R2 = 0.71, P &lt; 0.01 (n = 304). Preservation of urine with glycerol (70 mL/L) and storage at -20 degrees C yielded &gt; 80% recovery of LH and FSH after 51 weeks; this was comparable with recovery for acetone extracts of urine. Untreated urine showed loss of activity by 4 weeks of storage. Preserving urine specimens with glycerol is a simple method of storage for longitudinal study and compares favorably with acetone extraction. IFMAs can measure urinary gonadotropins reproducibly over a wide range of pH and osmotic conditions.
Immunoassays for serum and urine myoglobin: myoglobin clearance assessed as a risk factor for acute renal failure
Authors: Wu A H , Laios I , Green S , Gornet T G , Wong S S , Parmley L , Tonnesen A S , Plaisier B , Orlando R 
Published: January 2020

Abstract
We compared four immunoassays for serum and urine myoglobin. Within-run CVs were 5-13%, with biases seen between assays. Myoglobin was stable for 1 month in serum and 12 days in urine when the pH was adjusted to between 8.0 and 9.5. Hemoglobin caused no interference. We assayed 91 pairs of serum and timed urine specimens from 41 patients admitted for acute trauma or rhabdomyolysis. Most were treated with mannitol and alkalinization. Upon initial presentations, 21 patients with either low serum myoglobin concentrations (&lt; 400 micrograms/L) or high myoglobin clearances (&gt; or = 4 mL/min) had normal creatinine clearances and no clinical evidence of renal disease. The remaining 20 had low myoglobin clearances. Seven were in rhabdomyolysis-induced acute renal failure, or subsequently developed this complication. We suggest that low myoglobin clearance may indicate a high risk for developing renal failure or may be an early marker for kidney dysfunction. Low myoglobin clearance may prove useful in indicating failure of prophylactic treatment to clear myoglobin.
Enzyme immunoassay for erythrocyte aldose reductase
Authors: Nishimura C , Hamada Y , Tachikawa T , Ishikawa T , Gui T , Tsubouchi J , Hotta N , Tanimoto T , Urakami T 
Published: January 2020

Abstract
This two-site immunoassay measures erythrocyte aldose reductase by using monoclonal and polyclonal antibodies to recombinant human enzyme. Total incubation time is 2.5 h, and the limit of detection is &lt; 0.05 microgram/L. Analytical recovery tested with blood samples from healthy and diabetic individuals was 101-106%. Average CVs within and between assays were 3.7% and 4.8%, respectively. The enzyme content determined by this system correlated well with the activity of aldose reductase isolated from the same erythrocyte preparations. The amount of erythrocyte aldose reductase per milligram of hemoglobin was higher in women than in men (P &lt; 0.001), but no significant correlation was observed between the amount of enzyme and the age of the individuals. This assay method should provide useful clinical information to optimize administration of aldose reductase inhibitors for effective prevention and treatment of diabetic complications.
Monitoring tricyclic antidepressant concentrations in serum by fluorescence polarization immunoassay compared with gas chromatography and HPLC
Authors: Rao M L , Staberock U , Baumann P , Hiemke C , Deister A , Cuendet C , Amey M , Härtter S , Kraemer M 
Published: January 2020

Abstract
The fluorescence polarization immunoassay (FPIA) developed by Abbott to diagnose intoxication with tricyclic antidepressants was adapted for therapeutic drug monitoring and validated with chromatograpic methods to investigate its potential for this use. We compared serum concentrations of tricyclic antidepressants in vivo and in vitro obtained by FPIA with those by gas chromatography and HPLC. For amitriptyline, imipramine, clomipramine, and doxepin, the detection limit of the FPIA was 72, 71, 64, and 72 nmol/L (approximately 20 micrograms/L), respectively; that by gas chromatography was 18, 18, and 16 nmol/L (approximately 5 micrograms/L) for amitriptyline, imipramine and clomipramine, respectively; with HPLC the lower limit of detection for doxepin was 36 nmol/L (10 micrograms/L). The intra- and interassay CVs ranged from 3% to 6%. In patients being treated with amitriptyline, imipramine, clomipramine, and doxepin, at steady-state the correlation coefficients between FPIA and GC/HPLC results for split samples were 0.95, 0.92, 0.90 and 0.70, respectively. However, the slopes were close to unity only for amitriptyline and doxepin, being 0.6 for imipramine and 1.9 for clomipramine.
High-resolution 1H-NMR spectroscopy of blood plasma for metabolic studies
Authors: Wevers R A , Engelke U , Heerschap A 
Published: January 2020

Abstract
Although spin-echo techniques are often used to obtain 1H-NMR spectra of serum or plasma samples, they do not provide reliable quantitative analyses of metabolites. We present a standardized procedure, optimized for sensitivity, for using single-pulse 1H-NMR spectroscopy to analyze deproteinized plasma. The detection limit for various metabolites ranges between 2 and 40 mumol/L. The method allows quantitative analysis of many compounds of interest in studies of inborn errors of metabolism, including betaine and dimethylglycine, which cannot be measured easily with other techniques. For lactate, tyrosine, threonine, and alanine, we obtained results that correlated well with those obtained by established techniques. We also present a library containing resonance positions of 38 compounds occurring in plasma samples in health and disease, including 14 as-yet-unidentified resonances. As an example of the diagnostic power of the technique we show a spectrum of a plasma sample from a patient with 5-oxoprolinuria (pyroglutamic aciduria; McKusick 266130), an enzymatic defect in glutathione biosynthesis.
A simple enzyme-linked immunosorbent assay of human osteocalcin
Authors: Rosenquist C , Bonde M , Fledelius C , Qvist P 
Published: January 2020

Abstract
A heterologous ELISA for measurement of osteocalcin (bone Gla-protein) is described, involving biotinylated bovine osteocalcin and polyclonal antibodies. The log-linear range was 2.3-37.5 micrograms/L. Between-run (total) and within-run CVs (n = 10) were 5.7-6.4 and 5.9-6.1%, respectively; analytical recoveries ranged from 92% to 108%. Comparison of our method (x) with an RIA (y) yielded y = 1.10 x -0.01 microgram/L, Sylx = 1.4 micrograms/L, r = 0.958 (n = 167). Serum osteocalcin in healthy premenopausal women (n = 29) was 8.7 +/- 3.3 micrograms/L (mean +/- SD) and 11.8 +/- 4.5 micrograms/L in early-postmenopausal women (n = 24). The assay was evaluated in a double-blind placebo-controlled study of healthy early-postmenopausal women, treated for 12 months with either (a) estrogen valerate plus medroxyprogesterone acetate (n = 18), (b) 17 beta-estradiol and desogestrel (n = 22), or (c) placebo (n = 17). Serum osteocalcin decreased significantly (P &lt; 0.001) with either therapy, but increased (P &lt; 0.05) with placebo.