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- Burstedt, Marie, 1964-
(författare)
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Bothnia dystrophy, a clinical, genetical and electrophysiological study
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A high frequency of retinitis pigmentosa (RP) is found in Northern Sweden. In an inventory of autosomal recessive RP patients in Västerbotten County, a great number of cases with a unique phenotype was noticed, denoted Bothnia Dystrophy (BD). The aim of the study was to describe the phenotype, to determine the chromosomal location, and to identify the gene. Patients typically show night blindness from early childhood. Symptoms of defect macular function with a decrease of visual acuity can appear in early adulthood. The retinal fundus shows irregular white spots in a central, and parafoveal pattern along the arcades. Centrally areolar maculopathy develops and round circular atrophies are observed in the periphery. The disease was shown to be associated with a missense mutation in the RLBP1 gene resulting in an amino acid substitution (R234W) in the cellular retinaldehyde-binding protein (CRALBP). The R234W mutation was found in a homozygous state in 61 patients affected with BD. Ten patients were heterozygous for the R234W mutation, and presented a similar phenotype. No additional mutations in the coding sequence or exon-intron junctions were found. CRALBP is localised in retinal pigment epithelium (RPE), and Müller cells of the retina. In the RPE, CRALBP functions as a carrier protein for endogenous retinoids. Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages. A compromised rod function, dysfunction of the Müller cells, and indications of a disturbed function of the inner retina were found. With prolonged dark adaptation, a gradual increase in retinal sensitivity to light and an improvement of the ERG components occurred. The findings indicate a prolonged synthesis of photopigments, retardation of the visual process in the retinal pigment epithelium and a loss of retinal cells probably starting at a relative early age in BD. To evaluate the subjective visual function in BD patients, a battery of objective tests of visual function and composite score of the 25-item NEI-Visual Function Questionnaire (VFQ-25) were analyzed. We found that weighted distance logMAR visual acuity (WVA), had the strongest association with subjective visual function, and that there was a considerable loss of subjective and objective visual function with increasing age in BD patients. The prevalence of BD is as high as 1:3600 in Västerbotten County. The possibility that recycling of retinoids localized in the RPE might be impaired in BD might give future therapeutic possibilities. Due to the large and clinically well-characterized set of patients with this disease, they constitute a suitable study group.
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- Burstedt, Marie S, et al.
(författare)
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Associations between specific measures of vision and vision-related quality of life in patients with bothnia dystrophy, a defined type of retinitis pigmentosa.
- 2005
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Ingår i: Retina. - : Lippincott, Williams & Wilkins. - 0275-004X .- 1539-2864. ; 25:3, s. 317-323
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To assess the relationship between objective tests of visual function and vision-related quality of life in patients with Bothnia dystrophy (BD), a retinal dystrophy of retinitis pigmentosa type with progressive maculopathy. METHODS: Forty-nine patients were tested. Weighted distance logMAR visual acuity (WVA), weighted logMAR low contrast VA (WCS), and binocular visual field (VF) areas were calculated. Vision-related quality of life (VRQL) was assessed using the 25-item National Eye Institute-Visual Function Questionnaire (NEI-VFQ-25). Correlation statistics were used and adjusted analyses of the relationship between the composite score and the objective visual function tests were performed with multiple linear regression. RESULTS: VRQL was significantly correlated with age, WVA, WCS, and binocular VF areas (P < 0.001). Calculation of partial correlation coefficients showed age to be significantly correlated only with VF (V-4-e) area (P < 0.0001). Multiple linear regression analyses revealed age and WVA to be significantly associated with the NEI-VFQ-25 composite score (P < 0.02 and P = 0.001, respectively). WVA alone was the strongest predictor of self-reported experience of total visual function in BD patients (r 2= 0.69). CONCLUSIONS: A strong relationship between objective tests of visual function and patient perceived VRQL as assessed by a questionnaire was found. WVA was the strongest predictor and together with age explained almost 70% of the variability of the composite score of the questionnaire.
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- Burstedt, Marie S I, et al.
(författare)
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Effects of prolonged dark adaptation in patients with retinitis pigmentosa of Bothnia type : an electrophysiological study.
- 2008
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Ingår i: Doc Ophthalmol. - 0012-4486. ; 116:3, s. 193-205
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Bothnia dystrophy (BD) is a variant of recessive retinitis punctata albescens (RPA), caused by the missense mutation R233W in cellular retinaldehyde-binding protein (CRALBP), which is localized in the retinal pigment epithelium (RPE) and Müller cells of the retina. The purpose of this study was, by examining the electrophysiological responses of the retina, to evaluate the capacity of recovery of the whole retinal area and different cell types induced by extremely prolonged dark adaptation (DA) in BD disease and to gain further understanding of the pathogenesis of BD. Six young patients underwent bilateral full-field ERGs after 24 h of DA in one eye and standard DA in the fellow eye. The results were also compared with the effect of prolonged DA (10 h), previously studied in the same patients. After extremely prolonged DA (24 h) the rod b-wave and the mixed rod-cone a-wave responses reached normal though delayed amplitudes. An increase, up to normal level, in the oscillatory response was found. There was no obvious recovery of the cone response. We conclude that in young BD patients during extremely prolonged DA there is a significant additional capacity of recovery of rod function and also significant gain of activity in the inner retinal layer. A continuous but slow regeneration of rod photopigment seems to occur at least up to 24 h. The visual process in the RPE is retarded and CRALBP acts in this process; also, the Müller cells of the retina seem to be involved. The findings also support an extremely slow synthesis of photopigments and irreversibly disturbed cone function early in BD.
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- Burstedt, Marie S I, et al.
(författare)
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Retinal function in Bothnia dystrophy. An electrophysiological study.
- 2003
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Ingår i: Vision Research. - 0042-6989 .- 1878-5646. ; 43:24, s. 2559-2571
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Tidskriftsartikel (refereegranskat)abstract
- Using prolonged dark adaptometry, standard dark adaptation (DA) and prolonged DA full-field electroretinograms (ERGs), we analysed the retinal function in patients with Bothnia dystrophy (BD), a variant of recessive retinitis punctata albescens (RPA). A compromised rod and cone function, a likely dysfunction of the Müller cells, and indications of disturbed neuronal function of the inner retina, were found. With prolonged DA, a gradual increase in retinal sensitivity to light and an improvement of the ERG components occurred. The findings indicate a prolonged synthesis of photopigments, retardation of the visual process in the retinal pigment epithelium (RPE), and a loss of retinal cells, probably starting at a relatively early age in BD.
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- Dawidson, Ola, 1969, et al.
(författare)
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Project Portfolio Management - a multiple case study of six Swedish companies
- 2005
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Ingår i: In proceedings of the 12th International Product Development Management Conference (EIASM) in Copenhagen, June 2005.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents the results from a multiple case study of Project Portfolio Management practices among six Swedish companies. Project portfolio management has gained much interest among practitioners in recent years, while earlier research has shown that using project portfolio management in practice is complex as it involves crucial decisions about the companys future. Such research has so far focused on the practices in US and UK companies and the present paper is to be seen as a complement.The results from the study show that all of the companies concerned have formal processes for evaluating and choosing projects for the portfolio. However, only half of them consider the project portfolio as a factor in their decisions. Two of the companies review the project portfolio regularly, and two use project portfolio management tools and methods. The decisions on the project portfolio composition are made on a cross-functional basis with people from different levels and organizational units involved.
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