Four-parameter paired response curve for serial dilution assays

SummaryBeing a putative predictor of ischemic heart disease, the measurement of factor VII (FVTI) coagulant activity will be presumably requested to clinical laboratories with increasing frequency. To assess the influence on FVII assays of different thromboplastins and FVII-deficient plasmas we compared performances of all possible combinations of 5 thromboplastins and 6 deficient plasmas. The reproducibility of the clotting times of the dose-response curves for human and rabbit thromboplastins were acceptable (CV lower than 7%), whereas bovine thromboplastin had a higher CV. Reproducibility was very similar for all deficient plasmas when they were used in combination with a given thromboplastin. Responsiveness of the dose-response curve did not depend on the deficient plasma but rather on the thromboplastin: one rabbit thromboplastin was the least responsive, the bovine thromboplastin the most responsive, the human and the remaining two rabbit thromboplastins had intermediate responsiveness. Assay sensitivity to cold-activated FVII varied according to the thromboplastin: the bovine thromboplastin was the most sensitive, the human thromboplastin the least sensitive, of the three rabbit thromboplastins two were relatively sensitive, one was almost insensitive. In conclusion, our results indicate that thromboplastin rather than deficient plasma is the crucial factor in the standardization of FVII assay.

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Synchronized Inhibition of the Phospholipid Mediated Autoactivation of Factor XII in Plasma by β2-glycoprotein I and Anti-β2-glycoprotein I

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653871 ◽

1995 ◽

Vol 73 (05) ◽

pp. 798-804 ◽

Cited By ~ 48

Author(s):

Inger Schousboe ◽

Margit Søe Rasmussen

Keyword(s):

Lupus Erythematosus ◽

Lupus Anticoagulant ◽

Response Curve ◽

Inhibitory Effect ◽

Factor Xii ◽

High Antibody ◽

Contact Activation ◽

Maximal Inhibition ◽

Lupus Anticoagulants ◽

Glycoprotein I

SummaryLupus anticoagulants are a group of antibodies commonly found in patients with autoimmune diseases such as systemic lupus erythematosus. Lupus anticoagulants inhibit phospholipid dependent coagulation and may bind to negatively charged phospholipids. Recent studies have suggested an association between anti-β2-glycoprotein I and a lupus anticoagulant, whose activity is frequently dependent on the presence of β2-glycoprotein I. Based on these observations, the effect of anti-β2-glycoprotein I on the autoactivation of factor XII in plasma was investigated. Autoactivation initiated by the presence of negatively charged phospholipids, but not by sulfatide, was strongly inhibited by immunoaffinity purified anti-β2-glycoprotein I. The dose-response curve of anti-β2-gly coprotein I was identical with that of a precipitating antibody, showing no inhibition at low and high antibody dilutions and maximal inhibition at an intermediate dilution. At high antibody concentrations, an increased rate of factor Xlla activation was observed. This increase was of the same magnitude as the decreased rate observed in plasma supplemented with the same amount of β2-glycoprotein I as in the plasma itself. This confirms the inhibitory effect of β2-GP-I on the contact activation and shows that inhibition is effective on the autoactivation of factor XII in plasma. The inhibitory action of β2-glycoprotein I was independent of the inhibition caused by the anti- β2-glycoprotein I/β2-glycoprotein I complex suggesting a synchronized inhibition of factor XII autoactivation by β2-glycoprotein I and anti-β2-gly coprotein I. The inhibition caused by the antibody is suggested to be caused by a reduced availability of negatively charged phospholipids due to the binding of the anti-β2- GP-I/β2-GP-I complex. This complex may be a lupus anticoagulant.

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OVARIAN ASCORBIC ACID DEPLETION TEST FOR LUTEINIZING HORMONE

Acta Endocrinologica ◽

10.1530/acta.0.0560619 ◽

1967 ◽

Vol 56 (4) ◽

pp. 619-625 ◽

Cited By ~ 1

Author(s):

Hans Jacob Koed ◽

Christian Hamburger

Keyword(s):

Ascorbic Acid ◽

Luteinizing Hormone ◽

Dose Response ◽

Response Curve ◽

Dose Response Curve ◽

Human Origin ◽

Response Curves ◽

Significant Difference ◽

The Mean ◽

Different Levels

ABSTRACT Comparison of the dose-response curves for LH of ovine origin (NIH-LH-S8) and of human origin (IRP-HMG-2) using the OAAD test showed a small, though statistically significant difference, the dose-response curve for LH of human origin being a little flatter. Two standard curves for ovine LH obtained with 14 months' interval, were parallel but at different levels of ovarian ascorbic acid. When the mean ascorbic acid depletions were calculated as percentages of the control levels, the two curves for NIH-LH-S8 were identical. The use of standards of human origin in the OAAD test for LH activity of human preparations is recommended.

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HYPERTROPHIC ADRENALS AND THEIR RESPONSE TO STRESS AFTER LESIONS IN THE MEDIAN EMINENCE OF TOTALLY HYPOPHYSECTOMIZED PIGEONS

Acta Endocrinologica ◽

10.1530/acta.0.0370565 ◽

1961 ◽

Vol 37 (4) ◽

pp. 565-576 ◽

Cited By ~ 19

Author(s):

Richard A. Miller

Keyword(s):

Dose Response ◽

Median Eminence ◽

Response Curve ◽

Liver Parenchyma ◽

Dose Response Curve ◽

Pars Distalis ◽

Adrenal Enlargement ◽

Response To Stress ◽

Lethal Doses ◽

Chromaffin Tissue

ABSTRACT Four per cent formaldehyde, insulin, or epinephrine in oil was injected for 5 days into pigeons subjected to varying degrees of hypophysectomy alone or together with large lesions in the median eminence and hypothalamus. Adrenals atrophied after the removal of the pars distalis alone or together with the neurohypophysis in untreated pigeons but showed markedly hypertrophic interrenal tissue (cortex in mammals) after treatment with formaldehyde or insulin. The slope of the dose-response curve was similar in operated and unoperated pigeons. The accumulation of bile in the liver parenchyma, which may occur after removal of the pars distalis, is an endogenous stress which was associated regularly with adrenal hypertrophy. After very large lesions of the median eminence and ventral hypothalamus in addition to total hypophysectomy, adrenals hypertrophied rather than atrophied, and the response to formaldehyde paralleled that in intact and »hypohysectomized« pigeons. Interrenal tissue was stimulated regularly; chromaffin tissue was partially degranulated, sometimes showed hyperplasia with colchicine, but only occasionally appeared hypertrophied. Epinephrine in nearly lethal doses caused only minimal adrenal enlargement. After adrenal denervation followed by hypophysectomy, the adrenals were still stimulated by formaldehyde. It appears that the interrenal tissue of the pigeon responds to a humoral stimulus not of hypophyseal origin in the absence of the hypophyseal-hypothalamic system.

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PLASMA CORTICOSTEROID LEVELS AND ADRENAL ASCORBIC ACID AFTER INTRAVENOUS CORTICOTROPHIN INJECTIONS AND »STRESSFUL« STIMULI IN THE RAT

Acta Endocrinologica ◽

10.1530/acta.0.0390527 ◽

1962 ◽

Vol 39 (4) ◽

pp. 527-538 ◽

Cited By ~ 8

Author(s):

Pavo Hedner ◽

Claus Rerup

Keyword(s):

Ascorbic Acid ◽

Abdominal Surgery ◽

Response Curve ◽

Significant Rise ◽

Blocking Effect ◽

High Dose ◽

Ascorbic Acid Concentration ◽

Unilateral Adrenalectomy ◽

Subcutaneous Injections ◽

Hypophysectomized Rats

ABSTRACT Measurements of plasma corticosteroid levels and adrenal ascorbic acid concentration in steroid blocked and hypophysectomized rats were performed. It was found that prednisolone and dexamethasone were effective in blocking endogenous corticotrophin release within 3–4 hours after subcutaneous injection. These agents also prevented completely the normally occurring rise in plasma corticoid levels after exposure of the rats to ether. Abdominal surgery (unilateral adrenalectomy) resulted in a slight but significant rise in plasma corticoid levels in spite of dexamethasone blockade. The values of adrenal ascorbic acid were not affected significantly. The blocking effect of two daily subcutaneous injections of a high dose of dexamethasone persisted for about one week after the last injection. The sensitivity of the plasma corticoid response was essentially the same in hypophysectomized and dexamethasone blocked rats. The lower part of the log dose response curve was found to be clearly non-linear in the plasma corticoid method following intravenous corticotrophin injection. As a consequence the dose level in quantitative assays of intravenously injected corticotrophin are, in our hands, of the same order as in the adrenal ascorbic acid depletion method.

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ANTI-OVULATORY ACTIVITY OF STEROIDS ADMINISTERED BY GAVAGE IN THE ADULT OESTRUS RABBIT

Acta Endocrinologica ◽

10.1530/acta.0.042s017 ◽

1963 ◽

Vol 42 (2_Suppl) ◽

pp. S17-S30

Author(s):

Fred A. Kind ◽

Ralph I. Dorfman

Keyword(s):

Dose Response ◽

Active Compound ◽

Subcutaneous Injection ◽

Response Curve ◽

Parent Compound ◽

Dose Response Curve ◽

Relative Potency ◽

Reference Standard ◽

Highly Active ◽

Dose Levels

ABSTRACT Thirty-seven steroids have been studied as orally effective inhibitors of ovulation in the mated oestrus rabbit. Norethisterone served as the reference standard and a dose response curve was established between the 0.31 and 1.25 mg dose levels. Nine highly active anti-ovulatory compounds are described listed in a decreasing order of potency with norethisterone having the arbitrary value of one: 6-chloro-Δ6-dehydro-17α-acetoxyprogesterone (35), 6α-methyl-Δ1-dehydro-17α-acetoxyprogesterone (≥ 10), 6-fluoro-Δ6-dehydro-17α-acetoxyprogesterone(9), 6-methyl-Δ6-dehydro-17α-acetoxyprogesterone (5), Δ6-dehydro-17α-acetoxyprogesterone (≥ 3), 6α-methyl-17α-acetoxyprogesterone (2.6), 6-chloro-Δ1,6-bisdehydro-17α-acetoxyprogesterone (≥ 2), 2-hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one (≥ 2), and 6α-fluoro-16α-methyl-17α-acetoxyprogesterone (≥ 1.25). The anti-ovulatory activity of a compound was not related necessarily to the progestational activity of a compound nor to the anti-gonadotrophic activity as measured in parabiotic rats. 6-Chloro-Δ60dehydro-17-acetoxyprogesterone was as effective by gavage as previously shown by subcutaneous injection. 2-Hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one was at least 2.5 times more active by gavage than by injection. While 17α-acetoxyprogesterone was a very weak anti-ovulatory steroid, modifications of the structure by addition of methyl or halogen at the 6α position with or without unsaturation greatly increased the activity. 6-Chloro-Δ6-dehydro-27α-acetoxyprogesterone was the most active compound in this series showing a relative potency of 3500 times that of the parent compound 17α-acetoxyprogesterone.

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COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

Acta Endocrinologica ◽

10.1530/acta.0.0620663 ◽

1969 ◽

Vol 62 (4) ◽

pp. 663-670 ◽

Cited By ~ 8

Author(s):

Lars Carlborg

Keyword(s):

Sialic Acid ◽

Response Curve ◽

Sialic Acids ◽

Clear Cut ◽

Suitable Parameter ◽

Sufficient Degree ◽

Comparative Action ◽

Relative Potencies ◽

Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

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