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[Changes in the blood uric acid levels in patients with retinitis pigmentosa and in rats with hereditary retinal degeneration].

The content of uric acid was measured in the blood of patients suffering from retinitis pigmentosa, as well as in the blood, retina, brain, liver and urine of rats with inherited retinal degeneration in the course of postnatal development. It was found that in the patients with retinitis pigmentosa, the concentration of uric acid in the blood serum was 50% higher as compared to normals. On the 8th day of life the content of uric acid in the blood of the sick rats was equal to 150% as compared to the normal animals. This difference persisted during the subsequent postnatal life. In the rats with inherited retinal degeneration, the content of this purine in the retina, brain and liver was approximately the same as that seen in the normal animals in all the studied periods of life. Meanwhile statistically significant changes in the uric acid content in the sick animals' urine appeared at an age of 1.5-2 months. It is believed that the identical line of changes in the uric acid content in the blood of the sick persons and rats points to similarity of the experimental disease of the animals to the disease in humans.

Animals↗

Comparison of functional mobility performance with clinical vision measures in simulated retinitis pigmentosa.

Simulations of retinitis pigmentosa (RP) under various conditions of retinal illuminance were designed and investigated in order that they might be used in the mobility training of clients with early RP. Goggles incorporating a 2.5 neutral density (ND) filter with a 0.5-mm diameter pinhole were found to be a potentially useful simulation device for this purpose. This investigation also compared mobility performance with clinical vision measures under photopic, mesopic, and scotopic conditions of retinal illuminance. Although none of the clinical vision measures we used was entirely predictive of mobility performance, some measures were better predictors than others. For a severe constriction of the visual field and decreasing retinal illuminance, both edge contrast sensitivity and visual acuity, measured outdoors, accounted for a greater proportion of the variance in mobility performance than did low contrast visual acuity measured under the same circumstances. The same clinical vision measures, taken indoors, were of no value in predicting outdoor mobility performance.

Adult↗

Retinal detachment in retinitis pigmentosa.

Three cases of retinal detachment occurring in patients with retinitis pigmentosa are presented and three previously reported cases reviewed. All the detachments were rhegmatogenous. One patient had a horseshoe tear, one had oral bay tears, two had dialyses, one a giant tear and in one case the break was not specified. Three patients were high myopes. All the patients were young males. The five operable cases all responded satisfactorily to conventional surgery. Histologically apparent adhesions between retinal pigment epithelium and neuroretina have been described in advanced cases of retinitis pigmentosa in older patients and may not be present in younger patients with less advanced disease. Until these adhesions occur patients with retinitis pigmentosa may have no additional protection against retinal detachment.

Adolescent↗

Giant retinal tear and retinal detachment with underlying retinitis pigmentosa and hearing loss.

Few retinal detachments have been described in patients with retinitis pigmentosa and allied retinal disorders, with only two cases (both with hearing loss) reported in association with giant retinal tears. To further characterise clinical characteristics of giant retinal tear associated with retinitis pigmentosa, we reviewed the course of four eyes of three patients. Unexpectedly, all three individuals also suffered from congenital sensorineural hearing loss. One suffered from associated myopathy. Despite aggressive surgical management, three of the four eyes became blind. The diagnosis of retinal detachment preceded the diagnosis of photoreceptor dystrophy in two of the three patients. To date, giant retinal tears occurring with underlying retinitis pigmentosa have been described in five young individuals, all of whom had associated congenital sensorineural hearing loss.

Adolescent↗

[Cataract surgery in patients with retinitis pigmentosa].

BACKGROUND: Because of the retinal alterations visual acuity of patients with retinitis pigmentosa is more affected by loss of contrast than in normal persons. Therefore cataract in retinitis pigmentosa (mostly posterior subcapsular cataract) leads earlier to decreasing visual acuity than is expected from the lens opacity. In a retrospective study we have looked up all patients with retinitis pigmentosa and cataract which were operated between 1989 and 1997 at our department. PATIENT AND METHODS: Between 1989 and 1997 50 eyes of 36 patients (21 female, 15 male; mean age 51 +/- 11.4 years) with the diagnosis of retinitis pigmentosa and cataract underwent extracapsular cataract extraction and IOL-implantation. In a retrospective study we studied all case histories of these patients. Mean follow up time was 1.2 +/- 1.2 years. RESULTS: Preoperative visual acuity was 0.1 +/- 0.1, best postoperative visual acuity was 0.3 +/- 0.2. Visual field was not affected by cataract-surgery. Postoperative complications were not found. 2/3 of all patients were satisfied with the postoperative visual acuity, 1/3 of all patients did not give comments. CONCLUSION: In patients with retinitis pigmentosa cataract surgery leads to significant increase of visual acuity. Cataract extraction should not be with held from patients with retinal dystrophy.

Adult↗

[Management of retinitis pigmentosa. 8 patients treated for retinitis pigmentosa/Usher syndrome in Cuba].

Full ocular clinical examination including fundus photography, dark adaptation (but not ERG) was performed on six patients with retinitis pigmentosa and on two patients with Usher syndrome before and six months after being treated for three weeks in Cuba. Four men and four women (20 to 44 years) had surgery on both eyes, in addition to ozonotherapy, electric stimulation and oral/parenteral medication. The patients did not know what surgical procedures had been used. The medication continued several months after returning home. No gain in visual function was recorded. One patient had diplopia after treatment and needed surgery. Three patients experienced annoying side effects in visual function after treatment, especially photophobia. One of these had an increase of fundus pigmentation in a localized area.

Adult↗

Cellular immune responses to retinal antigens in retinitis pigmentosa.

Patients with retinitis pigmentosa and a group of controls were tested for their cellular immune response toward two retinal proteins, S-antigen and interphotoreceptor retinoid-binding protein (IRBP), as well as their reaction against two synthetic peptides ("M" and "N") derived from the sequence of S-antigen and peptide "R14", derived from IRBP. Positive responses to the retinal antigens were found in larger proportions and with higher levels in the patient group than in the controls. The difference between the two groups was statistically significant in their response to S-antigen, but the patients reacted better than the controls against the other antigens as well. Of particular interest was the finding that several patients responded to both retinal proteins and/or to their peptides. These patients suffered from severe retinal changes and the data are thus interpreted as suggesting that the responses to the retinal antigens are secondary to these changes and to nonphysiological release of retinal antigens.

Adult↗

Increased risk of autoimmune hypothyroidism in patients affected by retinitis pigmentosa.

Patients with Retinitis Pigmentosa (RP) show hemeralopia, restricted field of vision and reduced visual acuity, owing to the degeneration and proliferation of photoreceptors and a retinal pigment epithelium. The prevalence in Italy is 1:4,000. A certain number of "syndromic" associations have been described, and, in particular, also that with hypothyroidism, but very few cases have been studied. We describe a family of 40 people, spanning four generations, in which we have recorded the presence of autosomic dominant RP, associated with autoimmune hypothyroidism or with circulating antithyroid autoantibodies (ATA), currently considered as the expression of active autoimmune thyroiditis or a risk factor for this complaint. We measured, in all members, TSH, FT3, FT4, antithyroglobulin and antithyroperoxidase autoantibodies. A fundus oculi examination was performed in every subject, as well as a careful examine of the anterior region on the neck. A control population of 100 healthy people was also studied. Our data show a higher prevalence of ATA, statistically significant, in the patients with RP and in their relatives, compared with the control population and the data from the literature (13 cases over 40 = 32.5%; p < 0.01). 3 patients with RP and ATA were affected by clinically evident hypothyroidism. 10 patients with ATA were clinically euthyroid; 8 patients affected by RP did not show circulating ATA at the time of the study. The interest for the physician in this "syndromic" retinal distrophy reflects the need, emerging from our data, to test the thyroid function in the subjects with RP and in members of their families, since circulating ATA are considered a risk factor for the development of autoimmune hypothyroidism.

Autoantibodies↗

Retinal detachment and retinal holes in retinitis pigmentosa sine pigmento.

Retinal detachment and retinal holes in two family members with retinitis pigmentosa sine pigmento are reported. We believe these are the first such cases reported in the literature. We describe the presenting symptoms and management, including cryotherapy, scleral buckling procedure, and sulfur hexafluoride injection (SF6), resulting in stable visual acuity in one case and retinal reattachment and improved visual acuity in the other case.

Adult↗

Glycosaminoglycan synthesis by cultured human retinal pigmented epithelium from normal postmortem donors and a postmortem donor with retinitis pigmentosa.

Cultured human retinal pigmented epithelium (RPE) synthesized and secreted glycosaminoglycans (GAGs) with the characteristics of chondroitin sulfate, dermatan sulfate, and hyaluronic acid from radioactive precursors. Cells subcultured for up to 18 passages from normal RPE and from the RPE of a patient with X-linked retinitis pigmentosa synthesized and secreted the same types and proportions of GAGs as primary cultures of normal RPE. Extracts of native human interphotoreceptor matrix contained hyaluronic acid and chondroitin sulfate but little or no dermatan sulfate, and the chondroitin sulfate differed in electrophoretic mobility and enzyme susceptibility from the chondroitin sulfates secreted by cultured RPE. Cultured human choroidal cells and cultured human skin fibroblasts secreted a much higher proportion of hyaluronic acid than cultured RPE. This study demonstrates that the profile of GAGs synthesized from radioactive precursors and secreted by cultured human RPE is a specific and stable characteristic of these cells that is retained even after extensive proliferation in vitro.

Adolescent↗

Homozygous and heterozygous gly-188-Arg mutation of the rhodopsin gene in a family with autosomal dominant retinitis pigmentosa.

Autosomal dominant retinitis pigmentosa (adRP) may be caused by point mutations in the rhodopsin gene in up to 20% of Spanish families. Most of the rhodopsin mutations causing adRP have been reported in the heterozygous state. We describe a patient with adRP who is homozygous for a missense mutation at codon 188 in the second intradiscal domain of rhodopsin. All her sons are heterozygous for the mutation and show an RP phenotype suggesting complete penetrance for this mutation. The homozygous carrier of the mutation Gly-188-Arg in the rhodopsin gene showed a later subjective onset of symptoms than the heterozygotes, suggesting that the photoreceptor degeneration induced by the mutation is not dramatically influenced by mutant allele dosage.

Adult↗

Refractive errors of retinitis pigmentosa patients.

A retinitis pigmentosa (RP) population (268 eyes) had predominantly myopic refractive errors. Whereas 12% of a normal population have myopic refractions, myopia was found in 75% of 268 eyes of RP patients and in 95% of 41 eyes of X-linked RP patients. The spherical errors describe a single-peaked, skewed distribution, with a mean of -1.86 dioptres that is significantly (P less than 0.001) more myopic, by -2.93 D, than that of a normal population. The X-linked genetic group has a spherical mean of -5.51 D that is significantly (P less than 0.01) more myopic than the non-X-linked RP population. This X-linked spherical error distribution may be composed of two separate subdistributions. Astigmatic refractive errors greater than 0.5 D are found in 47% of this RP population, considerably in excess of the 19% of a normal population with such astigmatic errors.

Adolescent↗

Suppression of wild-type rhodopsin maturation by mutants linked to autosomal dominant retinitis pigmentosa.

Autosomal dominant retinitis pigmentosa (ADRP) has been linked to mutations in the gene encoding rhodopsin. Most RP-linked rhodopsin mutants are unable to fold correctly in the endoplasmic reticulum, are degraded by the ubiquitin proteasome system, and are highly prone to forming detergent-insoluble high molecular weight aggregates. Here we have reported that coexpression of folding-deficient, but not folding-proficient, ADRP-linked rhodopsin mutants impairs delivery of the wild-type protein to the plasma membrane. Fluorescence resonance energy transfer and co-precipitation studies revealed that mutant and wild-type rhodopsins form a high molecular weight, detergent-insoluble complex in which the two proteins are in close (<70 A) proximity. Co-expression of ARDP-linked rhodopsin folding-deficient mutants resulted in enhanced proteasome-mediated degradation and steady-state ubiquitination of the wild-type protein. These data suggested a dominant negative effect on conformational maturation that may underlie the dominant inheritance of ARDP.

Cell Line↗

Genetically engineered large animal model for studying cone photoreceptor survival and degeneration in retinitis pigmentosa.

Patients with retinitis pigmentosa (RP) typically develop night blindness early in life due to loss of rod photoreceptors. The remaining cone photoreceptors are the mainstay of their vision; however, over years or decades, these cones slowly degenerate, leading to blindness. We created transgenic pigs that express a mutated rhodopsin gene (Pro347Leu). Like RP patients with the same mutation, these pigs have early and severe rod loss; initially their cones are relatively spared, but these surviving cones slowly degenerate. By age 20 months, there is only a single layer of morphologically abnormal cones and the cone electroretinogram is markedly reduced. Given the strong similarities in phenotype to that of RP patients, these transgenic pigs will provide a large animal model for study of the protracted phase of cone degeneration found in RP and for preclinical treatment trials.

Animals↗

Homozygous tandem duplication within the gene encoding the beta-subunit of rod phosphodiesterase as a cause for autosomal recessive retinitis pigmentosa.

Autosomal recessive retinitis pigmentosa (ARRP) is a degenerative disease of photoreceptors in which defects in the rhodopsin and phosphodiesterase beta-subunit (PDEB) loci have been reported. To assess the involvement of PDEB in ARRP families from Spain, we screened a panel of 19 families for linkage to markers within or close to the PDEB gene. Homozygosity was also tested in cases of consanguinity. This combined approach ruled out PDEB as the cause of the disease in all but one of the families. Molecular characterization of the gene in that family (a consanguineous pedigree) revealed a homozygous 71-bp tandem duplication in exon 1 of the affected member, the parents being heterozygous. This defect causes a frameshift mutation which leads to a premature stop codon, suggesting that this mutant allele is the underlying cause of ARRP in this patient. According to the data presented here, the PDEB gene is not the main gene responsible for ARRP, but accounts for about 5% of the cases.

Base Sequence↗

A 3-bp deletion in the rhodopsin gene in a family with autosomal dominant retinitis pigmentosa.

Autosomal dominant retinitis pigmentosa (ADRP) has recently been linked to locus D3S47 (probe C17), with no recombination, in a single large Irish family. Other ADRP pedigrees have shown linkage at zero recombination, linkage with recombination, and no linkage, demonstrating genetic heterogeneity. The gene encoding rhodopsin, the rod photoreceptor pigment, is closely linked to locus D3S47 on chromosome 3q. A point mutation changing a conserved proline to histidine in the 23d codon of the gene has been demonstrated in affected members of one ADRP family and in 17 of 148 unrelated ADRP patients. We have sequenced the rhodopsin gene in a C17-linked ADRP family and have identified in the 4th exon and in-frame 3-bp deletion which deletes one of the two isoleucine monomers at codons 255 and 256. This mutation was not found in 30 other unrelated ADRP families. The deletion has arisen in the sequence TCATCATCAT, deleting one of a run of three x 3-bp repeats. The mechanism by which this occurred may be similar to that which creates length variation in so-called mini- and microsatellites. Thus ADRP is an extremely heterogeneous disorder which can result from a range of defects in rhodopsin and which can have a locus or loci elsewhere in the genome.

Amino Acid Sequence↗

A novel genetic study of Chinese families with autosomal recessive retinitis pigmentosa.

Autosomal recessive retinitis pigmentosa (arRP) is the commonest form of RP worldwide. To date 22 loci have been implicated in the pathogenesis of this disease; however none of these loci independently account for a significant proportion of recessive RP. Linkage studies of arRP in consanguineous families have been mainly based on homozygosity mapping, but this strategy cannot be applied in the case of non-consanguineous families. Therefore, we implemented a systematic approach for identifying the disease locus in three non-consanguineous Chinese families with arRP. Initially, linkage analysis using SNPs/microsatellite markers or mutation screening of known arRP genes excluded all loci/genes except RP25 on chromosome 6. Subsequently a whole genome scan for the three families using the 10K GeneChip Mapping Array was performed, in order to identify the possible disease locus. To the best of our knowledge this is the first report on the utilisation of the 10K GeneChip to study linkage in non-consanguineous Chinese arRP. This analysis indicates that the studied families are probably linked to the RP25 locus, a well defined arRP locus in other populations. The identification of another ethnic group linked to RP25 is highly suggestive that this represents a major locus for arRP.

Asian People↗

[Molecular analysis of the RPE65 gene in 72 Spanish families with autosomal recessive retinitis pigmentosa].

BACKGROUND: Autosomal recessive retinitis pigmentosa (arRP) is the most common form of retinitis pigmentosa (RP). It is characterized by a high degree of allelic and non-allelic genetic heterogeneity. Previously,it has been demonstrated that the RPE65 gene is responsible for 2% recessive or isolated RP cases and 16% Leber's congenite amaurosis cases. Although the concrete function of RPE65 is unknown as yet, it has been found to be involved in vitamin A metabolism and rhodopsin regeneration. PATIENTS AND METHOD: We studied the involvement of the RPE65 gene in 72 arRP Spanish families by means of indirect molecular and mutation analysis. RESULTS: The results obtained using the intragenic microsatellite marker D1S2803 allowed us to exclude RPE65 as the causative gene of the disease in 80.5% of the families studied. Three new variants of the RPE65 gene have been identified: IVS6-43delA, IVS6-42delT and IVS6-33CG. We found that IVS6-33C-->G was a common polymorphism. The other variants, namely IVS6-43delA and IVS6-42delT, were not identified in 150 control chromosomes studied. The segregation analysis of IVS6-42delT variant seemed to exclude it as being involved in the disease. CONCLUSIONS: Our results argue against the involvement of RPE65 gene in the families studied, indicating that the prevalence of RPE65 abnormalities in arRP Spanish families may be lower than that observed in other populations.

Carrier Proteins↗