scholarly journals THE VISUAL SYSTEM OF THE ALLIGATOR

1957 ◽  
Vol 40 (5) ◽  
pp. 703-713 ◽  
Author(s):  
George Wald ◽  
Paul K. Brown ◽  
Donald Kennedy
Keyword(s):  
Absorption Spectrum ◽  
Visual System ◽  
Dark Adaptation ◽  
Eye Tissues ◽  
Cone Pigments

The eye tissues and liver of the alligator contain vitamin A1 alone. The retina contains rhodopsin, typical in absorption spectrum (λmax 500 mµ); but synthesized in solution from neo-b retinene and opsin much more rapidly than are the frog, mammalian, or chicken rhodopsins previously examined. In this regard alligator rhodopsin resembles the rhodopsins and porphyropsins of fishes, all of which so far investigated are synthesized rapidly in solution. The rates of synthesis in vitro of frog and alligator rhodopsins are matched closely by the rates of rod dark adaptation in living frogs and alligators, measured electrophysiologically at the same temperature. Alligator rods dark-adapt, and alligator rhodopsin is synthesized in solution, at rates characteristically associated with cones and cone pigments in frogs, mammals, and birds.

Partition Coefficient of 133Xe between Blood and Eye Tissues

1975 ◽  
Vol 14 (04) ◽  
pp. 301-309
Author(s):  
A. Marczak ◽  
A. Moszczyńska-Kowalska ◽  
H. Kowalski
Keyword(s):  
Partition Coefficient ◽  
Aqueous Humour ◽  
Vitreous Body ◽  
Flow Measurements ◽  
Solubility Coefficient ◽  
Eye Muscles ◽  
Eye Tissues ◽  
Relative Solubility ◽  
Blood Flow Measurements

SummaryThe relative solubility coefficient of 133Xe and the tissue-blood partition coefficient for the aqueous humour vitreous body, conjunctiva and external eye muscles of the rabbit were determined in vitro at 37° C and at various haematocrit values. The partition coefficient for haematocrit 40 was: for the aqueous humour 0,49 ml/ml, for the vitreous body 0,50 ml/ml, for the conjunctiva 0,81 ml/g and for the external eye muscles 0,77 ml/g. It was found that the solubility of 133Xe in rabbit erythrocytes is about 50 per cent higher than that in human red cells. The consequences of this fact for the precision of blood flow measurements by the method of tissue clearance are discussed.

scholarly journals Ophthalmic Drug Dosage Forms: Characterisation and Research Methods

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Przemysław Baranowski ◽  
Bożena Karolewicz ◽  
Maciej Gajda ◽  
Janusz Pluta
Keyword(s):  
Defense Mechanisms ◽  
Drug Application ◽  
Drug Dosage ◽  
Eye Drops ◽  
Eye Tissues ◽  
Ophthalmic Drug ◽  
Application Frequency

This paper describes hitherto developed drug forms for topical ocular administration, that is, eye drops, ointments,in situgels, inserts, multicompartment drug delivery systems, and ophthalmic drug forms with bioadhesive properties. Heretofore, many studies have demonstrated that new and more complex ophthalmic drug forms exhibit advantage over traditional ones and are able to increase the bioavailability of the active substance by, among others, reducing the susceptibility of drug forms to defense mechanisms of the human eye, extending contact time of drug with the cornea, increasing the penetration through the complex anatomical structure of the eye, and providing controlled release of drugs into the eye tissues, which allows reducing the drug application frequency. The rest of the paper describes recommendedin vitroandin vivostudies to be performed for various ophthalmic drugs forms in order to assess whether the form is acceptable from the perspective of desired properties and patient’s compliance.

scholarly journals Comparative study of oxytetracycline and doxycycline on calcium chelation: in-vitro assay

2017 ◽  
Vol 6 (5) ◽  
pp. 1160 ◽  
Author(s):  
Savitri Katlam ◽  
Yeshwant A. Deshmukh ◽  
Pradeep R. Jadhav
Keyword(s):  
Absorption Spectrum ◽  
Calcium Binding ◽  
Binding Assay ◽  
Pharmacokinetic Profile ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Calcium Chelation ◽  
Different Doses ◽  
Uv Absorption Spectrum

Background: Tetracycline class of antibiotics differ in their pharmacokinetic profile and chelating property. Objective of present study is to assess the effect of oxytetracycline and doxycycline on calcium chelationMethods: For estimation of calcium chelation of Oxytetracycline and Doxycycline, EDTA method (P. Trinder) and calcium binding assay was followed. Different doses of Oxytetracycline (25 mg, 50 mg and 100 mg) and Doxycycline (25 mg, 50 mg and 100 mg) were used in EDTA method and different concentrations of calcium were used in calcium binding assay. The procedure was done according to the standard methodology.Results: The intensity of colour appear to be increased with increase in dose of the Oxytetracycline (25 mg, 50 mg, 100 mg) as the concentration of calcium binding increases. But in Doxycycline intensity of colour is more with 100 mg as compared with 25 mg and 50 mg The UV absorption spectrum of solution of Oxytetracycline (1mM) was changed after the addition of CaCl2 to provide different concentration of Ca2+ (0.1, 0.5 and 1.0 mM).  With minor shift in the absorption coefficient and no shift in wavelength were observed for Doxycycline.Conclusions: The study concludes that oxytetracycline has more calcium chelating property than doxycycline.

Metachromasia Observed in the Living Eggs of Arbacia punctulata and its Cytochemical Analysis

Development ◽  
1959 ◽  
Vol 7 (2) ◽  
pp. 223-240
Author(s):  
Jacques Mulnard ◽  
Walter Auclair ◽  
Douglas Marsland
Keyword(s):  
Absorption Spectrum ◽  
Van Der Waals Forces ◽  
Point Of View ◽  
Acidic Polysaccharide ◽  
Arbacia Punctulata ◽  
Cytochemical Analysis ◽  
Basic Dyes ◽  
Living Material ◽  
Chemical Conditions

It has long been known that metachromasia (a change that occurs in the absorption spectrum of certain basic dyes when placed under certain conditions) can be used as a valuable, though not specific, cytochemical method. The physical as well as the chemical conditions promoting metachromasia or affecting its intensity have been studied in vitro on microscopic sections of fixed tissues and, sometimes, on living material by numerous investigators (see Dalcq & Massart, 1952). From a chemical point of view it can be assumed that metachromasia is due to ‘an electro-absorption of the cation of the basic dye by the acidic groupings of macromolecules, followed by an orientation of the organic skeleton of the dye by van der Waals forces’ (Massart, 1953). Studying the metachromasia of living bacterial suspensions, Massart came to the conclusion that the substance responsible for it must be an acidic polysaccharide localized at the surface of the bacteria.

Electroretinographic Determination of Spectral Sensitivity in Albino and Pigmented Brook Trout (Salvelinus fontinalis, Mitchill)

1971 ◽  
Vol 49 (12) ◽  
pp. 1030-1037 ◽  
Author(s):  
H. Kobayashi ◽  
M. A. Ali
Keyword(s):  
Absorption Spectrum ◽  
Spectral Sensitivity ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Narrow Band ◽  
Visible Spectrum ◽  
The Difference

A technique for recording electroretinograms from the unpunctured eyes in situ of living, anesthetized fish is described. This technique permits the use of the same fish in a number of experiments over a period of weeks, months, or years. Using this technique the spectral sensitivity of dark-adapted (scotopic) and light-adapted (photopic) fish was measured at 13 bands of the visible spectrum. The scotopic curves of albino and pigmented trout thus obtained in the winter have their maxima around 525 nm which differ from that of the absorption spectrum of the scotopic pigment in situ and in vitro of older fish obtained in the summer. The photopic curve of the pigmented fish is a broad one with humps around 425 nm, 545 nm, and 595 nm. The albino's curve has a relatively narrow band with a peak around 630 nm and a shoulder at about 550 nm. The difference between the shapes of the two curves may be ascribed to the increase in the intensity of light of longer wavelengths within the eyeball of the albino, due to reflection from blood vessels and sclera caused by the absence of pigmentation.

Spectral sensitivity of the electroretinogram b-wave in dark-adapted goldfish

1988 ◽  
Vol 1 (2) ◽  
pp. 159-168 ◽  
Author(s):  
Jonathan D. Nussdorf ◽  
Maureen K. Powers
Keyword(s):  
Absorption Spectrum ◽  
Spectral Sensitivity ◽  
Neural Activity ◽  
Dark Adaptation ◽  
Carassius Auratus ◽  
Action Spectrum ◽  
Absolute Threshold ◽  
Selective Loss

AbstractThe action spectrum of the ERG b-wave was measured under dark-adapted conditions in intact goldfish (Carassius auratus). It is substantially broader than the absorption spectrum of goldfish rod porphyropsin. Neither prolonged dark adaptation nor removal of possible efferent neural activity affected its shape. Moreover, a 682-nm background did not produce a selective loss of sensitivity to long wavelengths. The results imply that the spectral sensitivity of the b-wave in dark-adapted goldfish reflects the influence of at least two photoreceptor types which act as a single univariant mechanism near absolute threshold.

scholarly journals Chemical changes associated with aging of collagen in vivo and in vitro

1969 ◽  
Vol 112 (4) ◽  
pp. 397-405 ◽  
Author(s):  
Kalindi Deshmukh ◽  
Marcel E. Nimni
Keyword(s):  
Absorption Spectrum ◽  
Neutral Salt ◽  
Unsaturated Aldehyde ◽  
Salt Solutions ◽  
Rat Skin ◽  
Soluble Collagen ◽  
Insoluble Collagen ◽  
Cross Links

Collagen extracted from rat skin by neutral-salt solutions contains less aldehydes than the more insoluble collagen fractions. The concentration of aldehydes in collagen is directly related to its capacity to form stable cross-linked gels, which do not redissolve on cooling and become more insoluble in a variety of reagents. Whereas the absorption spectrum of neutral-salt-soluble collagen treated with N-methylbenzothiazolone hydrazone resembles that of acetaldehyde, the more insoluble collagen fractions show increasing amounts of a component that behaves like an αβ-unsaturated aldehyde. The ratio between α- and β-sub-units present in a particular fraction of soluble collagen seems to be constant and independent of the age of the animal. Neutral-salt-soluble collagen, which has a low concentration of β-components, will generate intramolecular bonds if gelled at 37°. These intramolecular bonds seem to precede the formation of stable intermolecular cross-links, since these gels can redissolve when cooled to yield a soluble collagen with a higher content of β-components of intramolecular origin.

The effect of light history on the photolysability of human visual pigments in situ

1966 ◽  
Vol 164 (994) ◽  
pp. 96-105 ◽  
Keyword(s):  
Spectral Composition ◽  
Difference Spectra ◽  
Variable Intensity ◽  
Density Spectrum ◽  
Cone Pigments ◽  
History Of ◽  
Fundus Reflectometry ◽  
Light History

The foveae of two subjects were studied by the method of rapid fundus reflectometry (RFR). Difference spectra were obtained after the eye had dark-adapted for at least 12 min and then been exposed to a bleaching light of variable intensity and spectral composition. It is found that if the period of dark-adaptation is preceded by an exposure to intense light, designed to eliminate the previous light history of the retina, the density spectrum is lower than in the absence of such a clearing exposure, provided the latter is such as to furnish on average more than one quantum per visual pigment molecule within approximately 500 msec. It is shown that, within limits, cone pigments studied with RFR show properties similar to those obtained with visual purple in vitro .

Sign in / Sign up

Export Citation Format

Share Document