Photochemistry of the Model Phototropic System Involving Flavins and Indoles–i. Fluorescence Polarization and Mo Calculations of the Direction of the Electronic Transition Moments in Flavins*

Kurtin, William E.; Song, Pill‐Soon

doi:10.1111/j.1751-1097.1968.tb08015.x

Cited by 37 publications

(27 citation statements)

References 22 publications

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“…Riboflavin or a flavoprotein has been previously suggested (3,11,13,14) . Riboflavin is yellow and in solution has absorption peaks in the oxidized state around 221-227, 265-270, 365-370, and near 445 nm (14,22) . Upon ultraviolet excitation, it fluoresces green (520-560 nm) .…”

Section: Resultsmentioning

confidence: 98%

MICROSPECTROPHOTOMETRY AND THE PHOTORECEPTOR OF PHYCOMYCES I

Wolken

1969

The Journal of Cell Biology

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Section: Resultsmentioning

confidence: 98%

MICROSPECTROPHOTOMETRY AND THE PHOTORECEPTOR OF PHYCOMYCES I

Wolken

1969

The Journal of Cell Biology

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“…Thus, using molecular orbital calculations of the wavelength dependence of isolated ravin dipole-orientation (e.g. Kurtin and Song 1968) may lead to misleading results if applied uncritically to infer the in-vivo status of the photoreceptor (Jesaitis 1974;Fukshansky and Steinhardt 1987).…”

Section: Discussionmentioning

confidence: 98%

Action spectra of the light-growth response of Phycomyces

1991

Planta

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The light-growth response of Phycomyces blakesleeanus (Burgeff) is a transient change in elongation rate of the sporangiophore caused by a change in light intensity. Previous investigators have found that the light-growth response has many features in common with phototropism; the major difference is that only the light-growth response is adaptive. In order to better understand the light-growth response and its relationship to phototropism, we have developed a novel experimental protocol for determining light-growth-response action spectra and have examined the effect of the reference wavelength and intensity on the shape of the action spectrum. The null-point action spectrum obtained with broadband-blue reference light has a small peak near 400 nm, a flat region from 430 nm to 470 nm, and an approximately linear decline in the logarithm of relative effectiveness above 490 nm. The shape of the action spectrum is different when 450-nm reference light is used, as has been shown previously for the phototropic-balance action spectrum. However, the action spectrum of the light-growth response differs from that for phototropic balance, even when the same reference light (450 nm) is used. Moreover, for the light-growth response, the relative effectiveness of 383-nm light decreases as the intensity of the 450-nm reference light increases; this trend is the opposite of that previously found for phototropic balance. The dependence of the lightgrowth-response action spectrum on the reference wavelength, its difference from the phototropic-balance action spectrum, and the reference-intensity dependence of the relative effectiveness at 383 nm may be attributable to dichroic effects of the oriented photoreceptor(s), and to transduction processes that are unique to the light-growth response.

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“…The normal equine cornea is 0.8—1.0 mm thick [1], therefore, with exception of very deep corneal ulcers, the risk for endothelial damage is judged to be low. To reduce the risk for uncontrolled UV damage to the cornea, we used a light source with an emission spectrum coinciding with the peak absorption of riboflavin in the UVA-part of the spectrum (365 nm) [43], an optical system providing a rather constant beam intensity across the area illuminated to prevent hot spots and a shutter that allows light-exposure of a well defined area of tissue to avoid incidental damage to limbal stem cells. Furthermore, the radiant exposure and the irradiance used were below the threshold for damaging the human eye by UVA [28,44].…”

Section: Discussionmentioning

confidence: 99%

Corneal cross-linking in 9 horses with ulcerative keratitis

et al. 2013

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BackgroundCorneal ulcers are one of the most common eye problems in the horse and can cause varying degrees of visual impairment. Secondary infection and protease activity causing melting of the corneal stroma are always concerns in patients with corneal ulcers. Corneal collagen cross-linking (CXL), induced by illumination of the corneal stroma with ultraviolet light (UVA) after instillation of riboflavin (vitamin B2) eye drops, introduces crosslinks which stabilize melting corneas, and has been used to successfully treat infectious ulcerative keratitis in human patients. Therefore we decided to study if CXL can be performed in sedated, standing horses with ulcerative keratitis with or without stromal melting.ResultsNine horses, aged 1 month to 16 years (median 5 years) were treated with a combination of CXL and medical therapy. Two horses were diagnosed with mycotic, 5 with bacterial and 2 with aseptic ulcerative keratitis. A modified Dresden-protocol for CXL could readily be performed in all 9 horses after sedation. Stromal melting, diagnosed in 4 horses, stopped within 24 h. Eight of nine eyes became fluorescein negative in 13.5 days (median time; range 4–26 days) days after CXL. One horse developed a bacterial conjunctivitis the day after CXL, which was successfully treated with topical antibiotics. One horse with fungal ulcerative keratitis and severe uveitis was enucleated 4 days after treatment due to panophthalmitis.ConclusionsCXL can be performed in standing, sedated horses. We did not observe any deleterious effects attributed to riboflavin or UVA irradiation per se during the follow-up, neither in horses with infectious nor aseptic ulcerative keratitis. These data support that CXL can be performed in the standing horse, but further studies are required to compare CXL to conventional medical treatment in equine keratitis and to optimize the CXL protocol in this species.

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Photochemistry of the Model Phototropic System Involving Flavins and Indoles–i. Fluorescence Polarization and Mo Calculations of the Direction of the Electronic Transition Moments in Flavins*

Cited by 37 publications

References 22 publications

MICROSPECTROPHOTOMETRY AND THE PHOTORECEPTOR OF PHYCOMYCES I

MICROSPECTROPHOTOMETRY AND THE PHOTORECEPTOR OF PHYCOMYCES I

Action spectra of the light-growth response of Phycomyces

Corneal cross-linking in 9 horses with ulcerative keratitis

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