Comment Concerning the Effects of Light Intensity on Melatonin Suppression in the Review “Light Modulation of Human Clocks, Wake, and Sleep” by A. Prayag et al.

Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.

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Perception of a unilateral light stimulus

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1983.0108 ◽

1983 ◽

Vol 303 (1116) ◽

pp. 479-487 ◽

Cited By ~ 12

Keyword(s):

Light Intensity ◽

Dose Response ◽

Light Stimulus ◽

Biological Systems ◽

Response Curves ◽

Action Spectra ◽

Potential Problems ◽

Dose Response Curves ◽

Lack Of Knowledge

An organism can detect light direction given a gradient in light intensity within the organism. This gradient, which may be measured temporally or spatially, can be produced by screening or by refraction. The ramifications of the method of producing the gradient are potentially great, with possible effects on the shape of dose-response curves and action spectra. Two biological systems, amoebal phototaxis in Dictyostelium and phototropism by monocot seedlings, illustrate some potential problems. In the former system, no obvious mechanism exists for producing a substantial internal gradient in light intensity. This indicates our lack of knowledge concerning the amount of gradient necessary for an organism to measure light direction. In the latter system, it is evident that a gradient in light intensity is established by screening for second positive phototropism . However, screening may not be the method used for first positive phototropism. The implications of refraction as the mechanism involved in first positive phototropism are sufficiently great to warrant a thorough examination of the role of screening and refraction in first positive phototropism.

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Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647705 ◽

1974 ◽

Vol 32 (02/03) ◽

pp. 356-365 ◽

Cited By ~ 12

Author(s):

F Haverkate ◽

D. W Traas

Keyword(s):

Dose Response ◽

Fibrinolytic Activity ◽

Enzyme Concentration ◽

Response Curves ◽

Agar Gel ◽

Porcine Tissue ◽

Plate Assay ◽

Fibrin Plate ◽

Different Types ◽

Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

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BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

Acta Endocrinologica ◽

10.1530/acta.0.0410143 ◽

1962 ◽

Vol 41 (1) ◽

pp. 143-153 ◽

Cited By ~ 2

Author(s):

U. Henriques

Keyword(s):

Thyroid Hormone ◽

Dose Response ◽

Developmental Rate ◽

Response Curves ◽

Sodium Salts ◽

Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

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