The photoreaction of opsin regenerated with 9-demethylretinal has been investigated by UV-vis spectroscopy, flash photolysis experiments, and Fourier transform infrared difference spectroscopy. In addition, the capability of the illuminated pigment to activate the retinal G-protein has been tested. The photoproduct, which can be stabilized at 77 K, resembles more the lumirhodopsin species, and only minor further changes occur upon warming the sample to 170 K (stabilizing lumirhodopsin). UV-vis spectroscopy reveals no further changes at 240 K (stabilizing metarhodopsin I), but infrared difference spectroscopy shows that the protein as well as the chromophore undergoes further molecular changes which are, however, different from those observed for unmodified metarhodopsin I. UV-vis spectroscopy, flash photolysis experiments, and infrared difference spectroscopy demonstrate that an intermediate different from metarhodopsin II is produced at room temperature, of which the Schiff base is still protonated. The illuminated pigment was able to activate G-protein, as assayed by monitoring the exchange of GDP for GTP gamma S in purified G-protein, only to a very limited extent (approximately 8% as compared to rhodopsin). The results are interpreted in terms of a specific steric interaction of the 9-methyl group of the retinal in rhodopsin with the protein, which is required to initiate the molecular changes necessary for G-protein activation. The residual activation suggests a conformer of the photolyzed pigment which mimics metarhodopsin II to a very limited extent.

We identified three consanguineous Austrian kindreds with 15 members affected by autosomal recessive childhood-onset severe retinal dystrophy, a genetically heterogeneous group of disorders characterized by degeneration of the photoreceptor cells. A whole-genome scan by microarray analysis of single-nucleotide polymorphisms (ref. 2) identified a founder haplotype and defined a critical interval of 1.53 cM on chromosome 14q23.3-q24.1 that contains the gene associated with this form of retinal dystrophy. RDH12 maps in this region and encodes a retinol dehydrogenase proposed to function in the visual cycle. A homozygous 677A-->G transition (resulting in Y226C) in RDH12 was present in all affected family members studied, as well as in two Austrian individuals with sporadic retinal dystrophy. We identified additional mutations in RDH12 in 3 of 89 non-Austrian individuals with retinal dystrophy: a 5-nucleotide deletion (806delCCCTG) and the transition 565C-->T (resulting in Q189X), each in the homozygous state, and 146C-->T (resulting in T49M) and 184C-->T (resulting in R62X) in compound heterozygosity. When expressed in COS-7 cells, Cys226 and Met49 variants had diminished and aberrant activity, respectively, in interconverting isomers of retinol and retinal. The severe visual impairment of individuals with mutations in RDH12 is in marked contrast to the mild visual deficiency in individuals with fundus albipunctatus caused by mutations in RDH5, encoding another retinal dehydrogenase. Our studies show that RDH12 is associated with retinal dystrophy and encodes an enzyme with a unique, nonredundant role in the photoreceptor cells.

Mounting evidence suggests that voltage-gated L-type Ca2+ channels can modulate affective behaviour. We therefore explored the role of CaV1.3 L-type Ca2+ channels in depression- and anxiety-like behaviours using CaV1.3-deficient mice (CaV1.3-/-). We showed that CaV1.3-/- mice displayed less immobility in the forced swim test as well as in the tail suspension test, indicating an antidepressant-like phenotype. Locomotor activity in the home cage or a novel open-field test was not influenced. In the elevated plus maze (EPM), CaV1.3-/- mice entered the open arms more frequently and spent more time there indicating an anxiolytic-like phenotype which was, however, not supported in the stress-induced hyperthermia test. By performing parallel experiments in Claudin 14 knockout mice (Cldn14-/-), which like CaV1.3-/- mice are congenitally deaf, an influence of deafness on the antidepressant-like phenotype could be ruled out. On the other hand, a similar EPM behaviour indicative of an anxiolytic phenotype was also found in the Cldn14-/- animals. Using electroretinography and visual behavioural tasks we demonstrated that at least in mice, CaV1.3 channels do not significantly contribute to visual function. However, marked morphological changes were revealed in synaptic ribbons in the outer plexiform layer of CaV1.3-/- retinas by immunohistochemistry suggesting a possible role of this channel type in structural plasticity at the ribbon synapse. Taken together, our findings indicate that CaV1.3 L-type Ca2+ channels modulate depression-like behaviour but are not essential for visual function. The findings raise the possibility that selective modulation of CaV1.3 channels could be a promising new therapeutic concept for the treatment of mood disorders.

Ophthalmic findings in persons with RDH12 mutations suggest that RDH12 loss-of-function results in a characteristic form of early and progressive rod-cone degeneration distinct from that caused by mutations in other LCA genes. From our data, it seems likely that various clinical designations appropriately describe the diagnosis in these persons, including early-onset retinitis pigmentosa, LCA type II, and childhood retinal dystrophy.

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Purpose The aim of this study was to evaluate the efficacy of XEN® Gel Stent implantation in the treatment of primary open‐angle glaucoma (POAG) and pseudoexfoliation glaucoma (XFG) regarding the reduction of intraocular pressure (IOP) and number of IOP‐lowering medications over 2 years. Methods In this retrospective, observational, single‐centre study, patients with POAG or XFG underwent implantation of the XEN® Gel Stent with or without combined phacoemulsification. Changes in mean IOP, mean number of IOP‐lowering medications, number of postoperative interventions, complete or qualified surgical success rate (defined as IOP < 18 mmHg without or with IOP‐lowering medication, respectively) and complete surgical failure rate (defined as the necessity of a glaucoma‐related secondary surgical intervention or loss of light perception) were assessed 12 months (12M) and 24 months (24M) postoperatively. Results Seventy‐nine eyes of 63 patients with open‐angle glaucoma were included in the study (71% POAG, 29% XFG). Before surgery, mean IOP was 23.4 ± 7.9 mmHg. IOP was 14.6 ± 3.6 mmHg 12 months postoperatively (−31% from baseline, 95% CI −42% to −20%, n = 30, p < 0.001) and 14.8 ± 4.4 mmHg 24 months postoperatively (−29% from baseline, 95% CI −30% to −41%, n = 28, p < 0.001). Mean number of IOP‐lowering medications was significantly reduced from 2.7 ± 1.1 before surgery to 1.0 ± 1.2 (−69%, 95% CI −89% to 46%, p < 0.001) 12 months after surgery and 1.0 ± 1.2 (−64%, 95% CI −91% to −36%, p < 0.001) at 24 months after surgery. Complete surgical success was achieved in 39% (12M) and 34% (24M) of patients and qualified success in 29% (12M) and 27% (24M). 13 (16%) eyes were classified as complete surgical failure. In 62% of the patients needling procedures had to be performed. Conclusion The XEN® Gel Stent is an efficacious minimal invasive glaucoma surgery for primary open‐angle and pseudoexfoliation glaucoma, resulting in significant reduction of IOP and a reduction in glaucoma medications from baseline in two‐third of treated patients with 2‐year follow‐up. Frequent follow‐up examinations were mandatory to identify early and late bleb failure and additional needling procedures were necessary to reestablish aqueous flow.