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14. 2-(3-Benzoyl-1-pyridinio)-3,4-dioxo-cyclobutenolate.

Author

Kolev, Tsonko, Yancheva, Denitsa, Shivachev, Boris, Petrova, Rosica, and Spiteller, Michael

Subjects
ORGANIC compounds, CHEMICAL structure, PYRIDINIUM compounds, MOLECULAR structure, HYDROGEN bonding, DENSITY functionals
Abstract

The title compound, C16H9NO4, also known as the 3-benzoylpyridinium betaine of squaric acid, exhibits a dipolar electronic ground-state structure with a positively charged pyridinium fragment and a negatively charged squarate moiety. In the molecule, the two aromatic rings are twisted by 56.03 (2)° relative to one another. The three-dimensional packing of the molecules is stabilized by C—H··O· short contacts. [ABSTRACT FROM AUTHOR]

Published
2005
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15. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells

Author

Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., Donaldson, Paul J., Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., and Donaldson, Paul J.

Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (PH2O) some 20 times higher than AQP0, AQP5 could function to modulate PH2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative PH2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl2, an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of PH2O, with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg2+-sensitive contribution to PH2O. When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg2+-sensitive PH2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating PH2O in the outer cortex.

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16. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells

Author

Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., Donaldson, Paul J., Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., and Donaldson, Paul J.

Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (PH2O) some 20 times higher than AQP0, AQP5 could function to modulate PH2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative PH2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl2, an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of PH2O, with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg2+-sensitive contribution to PH2O. When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg2+-sensitive PH2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating PH2O in the outer cortex.

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17. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells

Author

Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., Donaldson, Paul J., Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., and Donaldson, Paul J.

Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (PH2O) some 20 times higher than AQP0, AQP5 could function to modulate PH2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative PH2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl2, an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of PH2O, with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg2+-sensitive contribution to PH2O. When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg2+-sensitive PH2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating PH2O in the outer cortex.

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18. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells

Author

Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., Donaldson, Paul J., Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., and Donaldson, Paul J.

Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (PH2O) some 20 times higher than AQP0, AQP5 could function to modulate PH2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative PH2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl2, an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of PH2O, with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg2+-sensitive contribution to PH2O. When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg2+-sensitive PH2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating PH2O in the outer cortex.

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19. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells

Author

Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., Donaldson, Paul J., Petrova, Rosica S., Webb, Kevin F., Vaghefi, Ehsan, Walker, Kerry, Schey, Kevin L., and Donaldson, Paul J.

Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (PH2O) some 20 times higher than AQP0, AQP5 could function to modulate PH2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative PH2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl2, an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of PH2O, with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg2+-sensitive contribution to PH2O. When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg2+-sensitive PH2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating PH2O in the outer cortex.

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20. Four cyclo­alkane­spiro-4′-imidazolidine-2′,5′-dithiones.

Author

Shivachev, Boris, Petrova, Rosica, Marinova, Petja, Stoyanov, Neyko, Ahmedova, Anife, and Mitewa, Mariana

Subjects
*KETONES, *ORGANOSULFUR compounds, *CYCLIC compounds, *ALKANES, *HYDROGEN bonding
Abstract

The crystal structures of four cyclo­alkane­spiro-4′-imidazolidine-2′,5′-dithiones, namely cyclo­pentane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.4]­nonane-2,4-dithione}, C7H10N2S2, cyclo­hexane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.5]decane-2,4-dithione}, C8H12N2S2, cyclo­heptane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-diaza­spiro­[4.6]undecane-2,4-dithione}, C9H14N2S2, and cyclo­octane­spiro-4′-imidazolidine-2′,5′-dithione {systematic name: 1,3-di­aza­spiro­[4.7]dodecane-2,4-dithione}, C10H16N2S2, have been determined. The three-dimensional packing in all of the structures is based on closely similar chains, in which hydantoin moieties are linked through N—H⋯S hydrogen bonding. The size of the cyclo­alkane moiety influences the degree of its deformation. In the cyclo­octane compound, the cyclo­octane ring assumes both boat–chair and boat–boat conformations. [ABSTRACT FROM AUTHOR]

Published
2006
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21. Dimorphism in 3′-amino­cyclo­hexane­spiro-5′-hydantoin.

Author

Shivachev, Boris, Petrova, Rosica, and Naydenova, Emilia

Subjects
*ORGANONITROGEN compounds, *NITROGEN compounds, *CRYSTALLIZATION, *MOLECULAR structure, *HYDROGEN bonding
Abstract

The title compound [systematic name: 1′-amino­cyclo­hexane­spiro-4′-imidazole-2′,5′(3′ H,4′ H)-dione], C8H13N3O2, has been synthesized and was found to crystallize in two different structures, both monoclinic and both with the same P21/ c space group. In the first structure, there are two mol­ecules in the asymmetric unit, one of which uses all of its hydrogen-bond donors and acceptors and forms undulating layers, while the other forms chains propagating perpendicular to the layers. In the second structure, there is only one independent mol­ecule and the packing is based on a chain structure mediated by hydrogen bonding between the hydantoin moieties and further grouped into hydro­philic layers separated by layers of the hydro­phobic cyclo­hex­yl groups. [ABSTRACT FROM AUTHOR]

Published
2005
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22. Intracellular hydrostatic pressure regulation in the bovine lens: a role in the regulation of lens optics?

Author

Chen Y, Petrova RS, Qiu C, and Donaldson PJ

Subjects
Animals, Capsaicin pharmacology, Cattle, Hydrostatic Pressure, Mice, Water pharmacology, Lens, Crystalline, TRPV Cation Channels
Abstract

The optical properties of the bovine lens have been shown to be actively maintained by an internal microcirculation system. In the mouse lens, this water transport through gap junction channels generates an intracellular hydrostatic pressure gradient, which is subjected to a dual feedback regulation that is mediated by the reciprocal modulation of the transient receptor potential vanilloid channels TRPV1 and TRPV4. Here we test whether a similar feedback regulation of pressure exists in the bovine lens and whether it regulates overall lens optics. Lens pressure was measured using a microelectrode/pico-injector-based pressure measurement system, and lens optics were monitored in organ cultured lenses using a laser ray tracing system. Like the mouse, the bovine lenses exhibited a similar pressure gradient (0 to 340 mmHg). Activation of TRPV1 with capsaicin caused a biphasic increase in surface pressure, while activation of TRPV4 with GSK1016790A caused a biphasic decrease in pressure. These biphasic responses were abolished if lenses were preincubated with either the TRPV1 inhibitor A-889425 or the TRPV4 inhibitor HC-067047. While modulation of lens pressure by TRPV1 and TRPV4 had minimal effects on lens power and overall vision quality, the changes in lens pressure did induce opposing changes to lens geometry and its gradient of refractive index that effectively kept lens power constant. Hence, our results suggest that the TRPV1/4-mediated feedback control of lens hydrostatic pressure operates to ensure that any fluctuations in lens water transport, and consequently water content, do not result in changes in lens power and therefore overall vision quality.

Published
2022
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23. Dynamic functional contribution of the water channel AQP5 to the water permeability of peripheral lens fiber cells.

Author

Petrova RS, Webb KF, Vaghefi E, Walker K, Schey KL, and Donaldson PJ

Subjects
Animals, Aquaporin 5 antagonists & inhibitors, Aquaporins metabolism, Cell Membrane drug effects, Epithelial Cells metabolism, Eye Proteins metabolism, Lens, Crystalline cytology, Lens, Crystalline drug effects, Mercuric Chloride pharmacology, Mice, Inbred C57BL, Models, Biological, Organ Culture Techniques, Permeability, Rats, Wistar, Species Specificity, Time Factors, Aquaporin 5 metabolism, Cell Membrane metabolism, Lens, Crystalline metabolism, Water metabolism
Abstract

Although the functionality of the lens water channels aquaporin 1 (AQP1; epithelium) and AQP0 (fiber cells) is well established, less is known about the role of AQP5 in the lens. Since in other tissues AQP5 functions as a regulated water channel with a water permeability (P H2O ) some 20 times higher than AQP0, AQP5 could function to modulate P H2O in lens fiber cells. To test this possibility, a fluorescence dye dilution assay was used to calculate the relative P H2O of epithelial cells and fiber membrane vesicles isolated from either the mouse or rat lens, in the absence and presence of HgCl 2 , an inhibitor of AQP1 and AQP5. Immunolabeling of lens sections and fiber membrane vesicles from mouse and rat lenses revealed differences in the subcellular distributions of AQP5 in the outer cortex between species, with AQP5 being predominantly membranous in the mouse but predominantly cytoplasmic in the rat. In contrast, AQP0 labeling was always membranous in both species. This species-specific heterogeneity in AQP5 membrane localization was mirrored in measurements of P H2O , with only fiber membrane vesicles isolated from the mouse lens, exhibiting a significant Hg 2+ -sensitive contribution to P H2O . When rat lenses were first organ cultured, immunolabeling revealed an insertion of AQP5 into cortical fiber cells, and a significant increase in Hg 2+ -sensitive P H2O was detected in membrane vesicles. Our results show that AQP5 forms functional water channels in the rodent lens, and they suggest that dynamic membrane insertion of AQP5 may regulate water fluxes in the lens by modulating P H2O in the outer cortex.

Published
2018
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