Die Sphärolithen der Linse

H, Pau

doi:10.1055/s-2008-1054431

Cited by 9 publications

(8 citation statements)

References 2 publications

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“…Because calcium salts have relatively low solubilities in aqueous solutions and the [Ca 2+ ] i detected in cataractous lenses [3,21,22,24] reaches values of >1000 nM in the center of the lens, it seemed likely that Ca 2+ would precipitate. This hypothesis is supported by reports of increased calcium associated with the insoluble lens fraction (as compared with the soluble fraction) of cataractous human lenses [35] and the finding of calcium oxalate or calcium carbonate crystals in human cataractous lenses [38][39][40].…”

Section: The Cataractous Lens: a Mineralized Organ?mentioning

confidence: 62%

Connexin Mutants Compromise the Lens Circulation and Cause Cataracts through Biomineralization

Berthoud

Gao

Minogue

et al. 2020

IJMS

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Gap junction-mediated intercellular communication facilitates the circulation of ions, small molecules, and metabolites in the avascular eye lens. Mutants of the lens fiber cell gap junction proteins, connexin46 (Cx46) and connexin50 (Cx50), cause cataracts in people and in mice. Studies in mouse models have begun to elucidate the mechanisms by which these mutants lead to cataracts. The expression of the dominant mutants causes severe decreases in connexin levels, reducing the gap junctional communication between lens fiber cells and compromising the lens circulation. The impairment of the lens circulation results in several changes, including the accumulation of Ca2+ in central lens regions, leading to the formation of precipitates that stain with Alizarin red. The cataract morphology and the distribution of Alizarin red-stained material are similar, suggesting that the cataracts result from biomineralization within the organ. In this review, we suggest that this may be a general process for the formation of cataracts of different etiologies.

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Section: The Cataractous Lens: a Mineralized Organ?mentioning

confidence: 62%

Connexin Mutants Compromise the Lens Circulation and Cause Cataracts through Biomineralization

Berthoud

Gao

Minogue

et al. 2020

IJMS

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“…T o our knowledge this type of nuclear vacuoles have not been described before, although they should have been observed. The vacuoles were found in the grey nuclear cataracts in contrast to the crystalline spheres formed by calcium phosphate described to be typical for the 'red' or brown nuclear cataract (Pau 1984). The slit-lamp appearance was similar to subcapsular or cortical vacuoles although these are much more distinct.…”

Section: Discussionmentioning

confidence: 75%

“…Any formed opacities in the nucleus were earlier considered to be of congenital origin. However, some crystalline formations can appear in the nucleus of the adult lens (Harding et al 1983;Pau 1984). Vacuoles or vacuole-like formations are typical findings in the subcapsular cataract, but are also found in the normal cortex.…”

mentioning

confidence: 99%

Nuclear vacuoles in nuclear cataract

Palmquist

Philipson

1986

Acta Ophthalmologica

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The human lens nucleus has always been described as a homogeneous part of the lens, and if any distinct opacities are found, these are considered to be congenital. However, in lenses with nuclear cataract, both of senile type and those induced by hyperbaric oxygen, we have found relatively transparent vacuoles in the nucleus of similar appearance as cortical vacuoles. In cataracts induced by hyperbaric oxygen the vacuoles were reversible to some extent. The vacuoles have been investigated with slit-lamp photography and quantitative microradiography. Nuclear vacuoles were found in 11 out of 25 patients treated with hyperbaric oxygen compared to 19 out of 100 pre-operatively examined senile nuclear cataracts. In the microradiographs the vacuoles appeared as dark rounded areas with a lower dry mass content (approximately 0.30 g X cm-3) than the surroundings (approximately 0.50 g X cm-3).

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“…Cataract formation associated with calcium precipitation may be a common process. Human cataractous lenses have previously been reported to contain increased [Ca 2+ ] i and calcium oxalate or calcium carbonate crystals 33–36. In homozygous Cx50D47A lenses, the Alizarin red staining localized to the same region occupied by the cataract, and its overall pattern of staining resembled the cataract morphology.…”

Section: Discussionmentioning

confidence: 88%

The Connexin50D47A Mutant Causes Cataracts by Calcium Precipitation

Berthoud

Gao

Minogue

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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Purpose Mutations in connexin50 (Cx50) and connexin46 (Cx46) cause cataracts. Because the expression of Cx46fs380 leads to decreased gap junctional coupling and formation of calcium precipitates, we studied Cx50D47A lenses to test whether Cx50 mutants also cause cataracts due to calcium precipitation. Methods Connexin levels were determined by immunoblotting. Gap junctional coupling conductance was calculated from intracellular impedance studies of intact lenses. Intracellular hydrostatic pressure was measured using a microelectrode/manometer system. Intracellular free calcium ion concentrations ([Ca 2+ ] i ) were measured using Fura-2 and fluorescence imaging. Calcium precipitation was assessed by Alizarin red staining and compared to the distribution of opacities in darkfield images. Results In Cx50D47A lenses, Cx50 levels were 11% (heterozygotes) and 1.2% (homozygotes), and Cx46 levels were 52% (heterozygotes) and 30% (homozygotes) when compared to wild-type at 2.5 months. Gap junctional coupling in differentiating fibers of Cx50D47A lenses was 49% (heterozygotes) and 29% (homozygotes), and in mature fibers, it was 24% (heterozygotes) and 4% (homozygotes) compared to wild-type lenses. Hydrostatic pressure was significantly increased in Cx50D47A lenses. [Ca 2+ ] i was significantly increased in Cx50D47A lenses. Alizarin red-stained calcium precipitates were present in homozygous Cx50D47A lenses with a similar distribution to the cataracts. Conclusions Cx50D47A expression altered the lens internal circulation by decreasing connexin levels and gap junctional coupling. Reduced water and ion outflow through gap junctions increased the gradients of intracellular hydrostatic pressure and concentrations of free calcium ions. In these lenses, calcium ions accumulated, precipitated, and formed cataracts. These results suggest that mutant lens fiber connexins lead to calcium precipitates, which may cause cataracts.

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Die Sphärolithen der Linse

Cited by 9 publications

References 2 publications

Connexin Mutants Compromise the Lens Circulation and Cause Cataracts through Biomineralization

Connexin Mutants Compromise the Lens Circulation and Cause Cataracts through Biomineralization

Nuclear vacuoles in nuclear cataract

The Connexin50D47A Mutant Causes Cataracts by Calcium Precipitation

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