scholarly journals The large variability in melatonin blood levels in ewes is under strong genetic influence

1998 ◽  
Vol 274 (4) ◽  
pp. E607-E610 ◽  
Author(s):  
Luis A. Zarazaga ◽  
Benoît Malpaux ◽  
Loys Bodin ◽  
Philippe Chemineau
Keyword(s):  
Plasma Concentration ◽  
Blood Levels ◽  
Plasma Samples ◽  
Repeatability Coefficient ◽  
Genetic Determination ◽  
Large Variability ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
The Mean

The present study was conducted to assess the degree of genetic determination of the variability in the mean nocturnal plasma concentration of melatonin in sheep. Three hundred twelve ewes born from 18 males and with known genealogy were sampled at the summer and the winter solstices. The nocturnal plasma melatonin concentration was defined as the mean of four plasma samples taken at hourly intervals in the middle of the night (2200–0200). Identity of the father ( P < 0.001) and the solstice ( P < 0.05) were significant. Melatonin concentrations varied considerably among individuals [338.4 ± 197.5 (SD) pg/ml; range 26.6–981.3 pg/ml] and between rams regarding the melatonin concentrations of their daughters (range from 202.9 to 456.3 pg/ml). Inheritance was analyzed by a statistical model that allows discrimination of genetic effects from nongenetic effects and that estimates repeatability and heritability coefficients. Both the repeatability coefficient between solstices (0.60) and heritability coefficient [0.45 ± 0.07 (SE)] were high. These results demonstrate that the variability in plasma melatonin concentration in ewes is under strong genetic control.

ENZYMATISCH-FLUOROMETRISCHE BESTIMMUNG DER CORTISOLBINDUNGSKAPAZITÄT DES PLASMA

1967 ◽  
Vol 56 (1) ◽  
pp. 99-106 ◽  
Author(s):  
K. Leybold ◽  
J. Rieper ◽  
L. Weissbecker
Keyword(s):  
Binding Capacity ◽  
Liver Microsomes ◽  
Mean Value ◽  
Female Rats ◽  
Plasma Samples ◽  
Simple Method ◽  
Adult Men ◽  
The Mean ◽  
Precision And Accuracy

ABSTRACT A simple method for the determination of cortisol-binding capacity is described. For saturation of the cortisol-binding proteins, plasma samples are incubated with an excess of cortisol. In the next step NADPH and liver microsomes of female rats are added. The microsomal Δ4-3-ketosteroid hydrogenase only reduces non protein-bound cortisol to tetrahydrocortisol-5α. Then the steroids are extracted by dichloromethane, and after some purification steps analyzed by fluorometry. Tetrahydrocortisol gives practically no fluorescence. The cortisol determined by this method corresponds to protein-bound cortisol and indicates the extent of cortisolbinding capacity. Precision and accuracy of the method were found to be good. The values of cortisol-binding capacity obtained by our method are compared with the results of other authors. The mean value of adult men was 25.5 ± 3.4 μg/100 ml, that of pregnant women, mens IX-X, 42.3 ± 4.2 μg/100 ml.

SEPARATION OF ANTIBODY-BOUND AND FREE HUMAN FOLLICLE-STIMULATING AND LUTEINIZING HORMONES BY ETHANOL-AMMONIUM ACETATE

1973 ◽  
Vol 72 (4) ◽  
pp. 643-653 ◽  
Author(s):  
A. Römmler ◽  
B. B. Saxena
Keyword(s):  
Ammonium Acetate ◽  
Acetate Solution ◽  
Plasma Samples ◽  
Human Pituitary ◽  
Luteinizing Hormones ◽  
Low Protein ◽  
The Mean ◽  
Post Menopausal ◽  
Normal Men

ABSTRACT The use of 66% ethanol containing 6.6% ammonium acetate provided a simple and economical method for the separation of antibody-bound and free 131I-labelled hormones in incubation mixtures of low protein concentrations used in the radioimmunoassay of human pituitary FSH and LH. The accuracy of the procedure was confirmed by similar results obtained in the evaluation of radiation damage to the tracer, binding of the tracer to the antibody and the separation of the antibody-bound and free 131I-labelled hormones by the use of ethanol-ammonium acetate solution and chromato-electrophoresis. The sensitivity of the measurement of the hormones was 10 pg with a precision of ± 5%; thus allowing the determination of hormone concentrations in as little as 20 to 50 μl of the plasma samples. There was a 98.5 to 102% recovery of the hormones added to the plasma samples of pre-determined hormone concentrations. The use of highly purified antigens for radioisotopic labelling and standard as well as purified antisera provided specific measurements of FSH and LH in the plasma. Various dilutions of a post-menopausal plasma sample yielded responses parallel to those obtained for the doseresponse curves of the FSH and LH standards by logit-log plots, thus confirming the validity of the assay. The mean plasma FSH and LH levels in normal men, children and in women during the luteal phase were 2.7 and 2.6, 1.1 and 1.2, and 1.8 and 2 ng/ml, respectively, whereas the plasma of hypophysectomized subjects showed trace to detectable levels of FSH and LH.

THE METABOLISM OF INJECTED PROGESTERONE IN THE EWE

1963 ◽  
Vol 26 (1) ◽  
pp. 65-73 ◽  
Author(s):  
M. G. BRUSH
Keyword(s):  
Plasma Levels ◽  
Blood Levels ◽  
Plasma Progesterone ◽  
The Mean ◽  
Mean Concentration

SUMMARY Plasma levels of progesterone and 20 α-hydroxypregn-4-en-3-one have been studied after intravenous (i.v.) and intramuscular (i.m.) injections of progesterone in sheep. I.v. injected progesterone was removed from the bloodstream very rapidly and it was necessary to give 50 mg. before it was possible to detect progesterone at times up to 10 min. after the injection. With 100 mg. amounts of progesterone injected i.v. the mean concentration in samples taken up to 10 min. after the injection was 34·7 μg./100 ml. plasma (range 4–110 μg./100 ml. in 9 samples), but after 1 hr. the mean level was 2·2 μg./100 ml. plasma (range 0–10 μg./100 ml. in 10 samples). The concentrations of 20 α-hydroxypregn-4-en-3-one were usually, but not always, less than those of progesterone. When progesterone was given by i.m. injection it was not possible to establish detectable blood levels. The effect of the injection vehicle was also studied for each injection route. Some new modifications of Short's method (1958) for the determination of plasma progesterone are described and discussed.

scholarly journals PH metric method for the determination of nicotinic acid in plasma

1977 ◽  
Vol 5 (4) ◽  
pp. 390-392
Author(s):  
J Gravesen
Keyword(s):  
Single Dose ◽  
Steady State ◽  
Standard Deviation ◽  
Plasma Concentration ◽  
Sustained Release ◽  
Nicotinic Acid ◽  
Plasma Samples ◽  
Slope Ratio ◽  
Male Patients

The acidimetric method for the determination of nicotinic acid (NA) using Lactobacillus plantarum ATCC 8014 (Lactobacillus arabinosus 17-5) has been simplified and thus made less time consuming, and the sensitivity has been increased fivefold by replacement of the titration by a pH determination. As the regression of the decrease in pH on the amount of NA was found linear within a range of 1 to 4 ng of NA per ml, the calculations were performed according to the slope-ratio principle. The NA concentration of plasma was determined with a coefficient of variation of 5 to 7%, which rose to about 10% at low NA concentrations. Assays of fasting plasma samples from 13 hyperlipidemic male patients showed a group mean NA concentration of 80 +/- 55 ng/ml (mean +/- 2 standard deviation), before treatment, and 705 +/- 544 ng/ml (mean +/- 2 standard deviation) during therapy with sustained release NA preparations, of which a single dose, ingested during steady-state conditions, doubled or tripled the plasma concentration within 1 to 3 h.

scholarly journals Accuracy of determination of the glomerular filtration marker iohexol by European laboratories as monitored by external quality assessment

2019 ◽  
Vol 57 (7) ◽  
pp. 1006-1011 ◽  
Author(s):  
Gunnar Nordin ◽  
Sara Ekvall ◽  
Carolina Kristoffersson ◽  
Ann-Sofie Jonsson ◽  
Sten-Erik Bäck ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Quality Assessment ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
External Quality Assessment ◽  
Plasma Samples ◽  
High Quality ◽  
External Quality ◽  
The Mean

Abstract Background Glomerular filtration is the most important kidney function. The most accurate glomerular filtration rate (GFR) estimates are based on the clearance of exogenous filtration markers. Of these, iohexol is the only exogenous marker that is included in an external quality assessment (EQA) scheme. The aim of the present study was to evaluate the performance of the European laboratories participating in Equalis’ EQA scheme for iohexol. Methods Weighed amounts of iohexol (Omnipaque) were added to plasma samples and distributed to laboratories participating in the EQA scheme for iohexol. All laboratories performed the assays in a blinded fashion. Results The number of participating laboratories varied between 27 and 34 during the study period. Iohexol was determined by HPLC in 77% of the laboratories and by UPLC/MS/MS methods in 15% of the laboratories. The mean interlaboratory coefficient of variation was 4.7% for the HPLC methods and 6.4% for the UPLC/MS/MS methods. The mean bias between calculated and measured iohexol values was –1.3 mg/L (95% confidence interval ±0.3) during the first part of the study period and 0.1 mg/L (±0.3) during the later part. Conclusions The low interlaboratory variation demonstrates that iohexol can be measured reliably by many laboratories and supports the use of iohexol as a GFR marker when there is a need for high quality GFR measurements.

A Method for the Quantitative Determination of the Antithrombin III (AT III) a Citivity in Plasma and Serum Using the Complex Formation with Heparin

1975 ◽  
Author(s):  
H. E. Karges ◽  
N. Heimburger ◽  
C. Loechelt
Keyword(s):  
Plasma Concentration ◽  
Antithrombin Iii ◽  
Ph Value ◽  
Immunological Methods ◽  
Good Reproducibility ◽  
High Dilution ◽  
At Iii ◽  
The Mean ◽  
Native Plasma

A prerequisite of most AT III assays is the defibrination of the samples. Defibrination of plasma, however, is generally associated with a loss of AT III. This especially true of heat defibrination. Furthermore, according to our experience, most of the functional determinations don’t correlate well with the immunological ones, and don’t provide reproducible results. Therefore, it was the aim of our investigations to establish a method which omits the defibrination and yields reproducible results.The method reported is based on the identity of AT III and heparin cofactor antithrombin II (AT II) respectively. AT III is converted by heparin from a progressive into an immediate inhibitor, allowing a plasma dilution of 1:50. Due to this high dilution, the defibrination step can be omitted and AT III determined in native plasma. To transform AT III completely into its heparin complex, 5 USP units heparin are used. α2-macro-globulin up to 400% of normal plasma concentration does not influence the assay. When determinations are performed at a certain pH value, good reproducibility is obtained. The mean error of determinations of the same sample does not exeed 4%. Maximal deviations were in the range of 5 to 10%. The results of functional determinations are compared with those obtained by two immunological methods. Deviations scarcely exeed the limits of methodical errors.

scholarly journals Genetic variability in plasma melatonin in sheep is due to pineal weight, not to variations in enzyme activities

1999 ◽  
Vol 277 (5) ◽  
pp. E792-E797 ◽  
Author(s):  
Steven L. Coon ◽  
Luis A. Zarazaga ◽  
Benoît Malpaux ◽  
Jean-Paul Ravault ◽  
Loys Bodin ◽  
...  
Keyword(s):  
Genetic Difference ◽  
Methyltransferase Activity ◽  
Group 13 ◽  
Melatonin Concentration ◽  
Plasma Melatonin ◽  
Genetic Groups ◽  
Extreme Groups ◽  
The Mean ◽  
Genetic Value

This study was conducted to determine the origin of the high variability in the mean nocturnal plasma melatonin concentration (MC) in sheep. Two extreme groups of 25 lambs each [low (L) and high (H)] were obtained by calculating their genetic value on the basis of the MC of their parents. The MC of lambs was significantly higher in the H group than in the L group (L: 189.7 ± 24.4 vs. H: 344.1 ± 33.0 pg/ml, P < 0.001). Within each group, 13 lambs were slaughtered during the day (D) and 12 lambs during the night (N). Pineal weight was significantly higher in the H group than in the L group (L: 83.5 ± 6.7 vs. H: 119.1 ± 9.2 mg, P < 0.01) but did not differ between D and N. The amount of melatonin released in vitro per milligram of pineal gland, the arylalkylamine N-acetyltransferase (AANAT) activity, the AANAT protein content, and the level of AANAT mRNA differed significantly between D and N but not with genetic group. Hydroxyindole O-methyltransferase activity did not differ significantly between D and N or between genetic groups. Therefore, the genetic difference in MC between the two groups of lambs was attributed to a difference in pineal size, not in enzymatic activity of the pinealocytes.

Oestriol and non-protein-bound oestriol concentrations in human peripheral plasma before labour and delivery

1986 ◽  
Vol 108 (1) ◽  
pp. 75-80 ◽  
Author(s):  
V. Moutsatsou ◽  
R. E. Oakey
Keyword(s):  
Plasma Concentration ◽  
Plasma Protein ◽  
Plasma Samples ◽  
Individual Subject ◽  
Peripheral Plasma ◽  
Uncomplicated Pregnancy ◽  
Apparent Concentration ◽  
The Mean ◽  
Mean Concentration ◽  
Centrifugal Ultrafiltration

ABSTRACT The concentration of oestriol and the proportion of this hormone not bound to plasma protein were measured using radioimmunoassay and centrifugal ultrafiltration respectively, in 55 samples of plasma obtained from 12 women in the last 2 to 7 weeks of uncomplicated pregnancy. Among individuals, the mean plasma concentration of oestriol varied from 25·8 to 94·8 nmol/l; in nine subjects, there was a tendency for oestriol concentrations to increase as delivery approached. The mean proportion of oestriol not bound to plasma protein in the different subjects varied from 13·1 to 18·9%, but values from any individual subject remained essentially constant during the periods of study. These measured values were used to calculate, for each sample, the apparent concentration of oestriol not bound to plasma protein. The results were combined with analogous values for oestradiol and progesterone obtained from the same plasma samples and described in a previous study. It was found that (i) the mean ratio of the concentration of oestriol and oestradiol was 0·75, (ii) the mean concentration of non-protein-bound oestriol was 8·7 times that of non-protein-bound oestradiol, and (iii) in individual subjects, there was no consistent trend as delivery approached in the ratio of the concentration of progesterone to that of oestriol in either the total or non-protein-bound form. J. Endocr. (1986) 108, 75–80

Malondialdehyde Kit Evaluated for Determining Plasma and Lipoprotein Fractions that React with Thiobarbituric Acid

1992 ◽  
Vol 38 (5) ◽  
pp. 704-709 ◽  
Author(s):  
M J Richard ◽  
B Portal ◽  
J Meo ◽  
C Coudray ◽  
A Hadjian ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Thiobarbituric Acid ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Plasma Samples ◽  
Very Low Density Lipoproteins ◽  
Lipid Fractions ◽  
Analytical Recovery ◽  
The Mean

Abstract The determination of thiobarbituric acid reactants (TBARs) is a widely used method for investigating overall lipid peroxidation. An assay kit that could be used with plasma and lipid fractions would facilitate standardization of the method. The results reported here indicate that the malondialdehyde (MDA) kit manufactured by Sobioda (Grenoble, France) complies with criteria of good analytical practices. The detection limit was 0.11 mumol of MDA per liter of plasma. The within-run (CV = 1.8-3.3%) and between-run (CV = 3.3-4.4%) precisions were acceptable. The analytical recovery of MDA after supplementing human plasma samples with tetraethoxypropane standards varied from 88% to 100%. The mean (SD) lipoperoxide concentration determined in 32 healthy adults, ages 20-40 years, was 2.51 (0.25) mumol/L. No significant sex-related difference was noted: 2.57 (0.28) in men vs 2.44 (0.20) mumol/L in women. Applying the method to lipid fractions showed that lipoprotein fractions contain relatively little MDA: 0.07 (0.03) mumol/L of plasma for very-low-density lipoproteins and 0.19 (0.10) mumol/L for low-density lipoproteins.

Assay of plasma testosterone during the first six months of life: importance of chromatographic purification of steroids

1995 ◽  
Vol 41 (8) ◽  
pp. 1146-1149 ◽  
Author(s):  
J S Fuqua ◽  
E S Sher ◽  
C J Migeon ◽  
G D Berkovitz
Keyword(s):  
Plasma Concentration ◽  
Ambiguous Genitalia ◽  
Plasma Testosterone ◽  
Plasma Samples ◽  
Chromatographic Purification ◽  
Direct Assay ◽  
Extraction And Purification ◽  
Over Time ◽  
Good Agreement

Abstract Determination of the plasma concentration of testosterone (T) is important in evaluating infants born with ambiguous genitalia and micropenis, and several commercially available kits provide a direct assay of T in unextracted plasma. Using plasma samples obtained from 36 subjects &lt; 6 months old, we compared the concentration of plasma T measured by RIA after extraction and purification by column chromatography with the T concentration measured in a direct assay. When aliquots of samples were purified before RIA, the concentration of T was markedly lower than in the direct assay. In the first 3 weeks postpartum, results of the direct assay were 3.8-fold greater than those obtained after purification. This difference decreased over time, and by age 2 months there was fairly good agreement between the two methods. These data indicate that some direct assays of plasma T are inappropriate during the first 2 months postpartum.

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