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Biomedical subjects

K Rüther

Publications and source records attributed to K Rüther.

At least 37 records · Page 2Linked to original sources
PubMed1998

Multifocal electroretinography in retinitis pigmentosa.

PURPOSE: To investigate the diagnostic potential of multifocal electroretinography for the evaluation of retinal affection by retinitis pigmentosa in a clinical setting. METHODS: For this prospective study, multifocal electroretinograms were obtained from 38 patients who matched the inclusion criteria of either a detectable photopic Ganzfeld response or visual fields of 10 degrees or more, and from 30 normal volunteers. Recordings were performed with the visual evoked response imaging system, using a resolution of 61 hexagonal elements within a 30-degree visual field. The results of the left eye of each patient and control subject were used for statistical evaluation by the Mann-Whitney U test. RESULTS: The 38 eligible patients included those with Usher syndrome types I and II (one patient and six patients, respectively) and those with autosomal-recessive (18), X-recessive (two), and autosomal-dominant (11) forms of retinitis pigmentosa. In 27 (71%) of these 38 patients, at least a central response of the multifocal electroretinogram was detectable. Loss of multifocal electroretinogram response density in patients with retinitis pigmentosa was significant (P < .00001) in all five eccentricity groups (concentric rings), with a progression from center to periphery. Implicit time was significantly elevated in the third eccentricity group (P < .0038) and increased further toward the periphery (P < .00001). The results did not differ notably between retinitis pigmentosa subgroups. CONCLUSIONS: Because the multifocal electroretinogram differentiates between affected and nonaffected retinal areas, eccentricity-dependent changes in both amplitude and implicit time were found. It can therefore add to the diagnostic information of many patients with retinitis pigmentosa.

Adolescent↗
PubMed1998

An L-type calcium-channel gene mutated in incomplete X-linked congenital stationary night blindness.

The locus for the incomplete form of X-linked congenital stationary night blindness (CSNB2) maps to a 1.1-Mb region in Xp11.23 between markers DXS722 and DXS255. We identified a retina-specific calcium channel alpha1-subunit gene (CACNA1F) in this region, consisting of 48 exons encoding 1966 amino acids and showing high homology to L-type calcium channel alpha1-subunits. Mutation analysis in 13 families with CSNB2 revealed nine different mutations in 10 families, including three nonsense and one frameshift mutation. These data indicate that aberrations in a voltage-gated calcium channel, presumably causing a decrease in neurotransmitter release from photoreceptor presynaptic terminals, are a frequent cause of CSNB2.

Amino Acid Sequence↗
PubMed1997

Molecular basis of choroideremia (CHM): mutations involving the Rab escort protein-1 (REP-1) gene.

Choroideremia (CHM) is an X-linked recessive eye disease that results from mutations involving the Rab escort protein-1 (REP-1) gene. In 18 patients deletions of different sizes have been found. Two females suffering from CHM were reported to have translocations that disrupt the REP-1 gene. In 22 patients, small mutations have been identified. Interestingly, these are all nonsense, frameshift or splice-site mutations; with one possible exception, missense mutations have not been found. This comprises all the known mutations in the disease.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Ocular findings in patients with autosomal dominant retinitis pigmentosa and Cys110Phe, Arg135Gly, and Gln344stop mutations of rhodopsin.

This report describes ocular findings obtained in four patients from three families with autosomal dominant retinitis pigmentosa (adRP) due to missense mutations in the rhodopsin gene. Phenotypes were characterized by standard ophthalmologic examinations, visual fields, electroretinography (ERG), dark adaptation, and two-color dark-adapted threshold perimetry. Two patients aged 38 and 45 years, respectively, from a family with the Cys110Phe mutation showed mild fundus changes without bone spicules as well as small arcuate scotomas in the inferior quadrants of their visual fields but displayed severe functional loss of rods and cones in the ERG. Two-color dark-adapted threshold perimetry revealed a regional type of degeneration. A 48-year-old patient with an Arg135Gly mutation had typical RP with concentrically narrowed visual fields and nondetectable ERG responses. Central visual functions were well preserved for a long time. Two-color dark-adapted threshold perimetry indicated a diffuse type of retinal degeneration. An 18-year-old patient with a Gln344stop mutation has been followed for 13 years. His ERG was clearly reduced at the age of 5 years; since that time, disease progression has been very slow. Currently, there are relatively mild alterations in visual acuity, rod sensitivity, and visual fields. Our findings confirm that there is a large phenotypic variety among patients with adRP and different rhodopsin mutations.

Adolescent↗
PubMed1997

[Juvenile neuronal ceroid lipofuscinosis (Batten-Mayou) disease. Ophthalmologic diagnosis and findings].

BACKGROUND: Juvenile neuronal ceroid lipofuscinosis (JNCL) is important to the ophthalmologist, since eye symptoms are usually the first evidence of the disease and permit establishment of an early diagnosis. The disorder usually begins with a dramatic loss of vision between age 4 and 10 due to bulls-eye maculopathy followed by rapid degeneration of the retina and pigment epithelium. Blindness results within 1 to 3 years after onset of symptoms. The further course of the disease is mainly determined by degradation of the CNS with motor and intellectual deficits. Most patients die before the age of 30. METHODS: A case of two sisters is presented to demonstrate eye findings and diagnostic procedures, emphasizing electrophysiologic and morphologic tests (peripheral blood smear, histology). RESULTS: Both sisters reported the first decrease in vision at the ages of 8 and 6 respectively; visual acuity at time of visit was light projection (20/400). Both had tapetoretinal degeneration with optic disc atrophy, narrowed vessels, pigment epitheliopathy and bullseye maculopathy. The ERG was almost extinguished in the older sister and greatly reduced in the younger one (scotopic more than photopic). Histologically, vacuolated lymphocytes were found in the peripheral blood smear, as were intracellular inclusions of the fingerprint and curvilinear type in the conjunctival biopsy. CONCLUSION: During the course of JNCL, it is very common for the vision to be affected at the age of 6-7. The correct diagnosis, however, is often made years later when massive neurologic symptoms such as seizures appear. When there is sudden loss of vision in a child of this age combined with a tapetoretinal degeneration, a biopsy or at least a peripheral blood smear should be performed.

Biopsy↗
PubMed1997

Mouse choroideremia gene mutation causes photoreceptor cell degeneration and is not transmitted through the female germline.

Choroideremia (CHM) is an X-linked progressive eye disorder which results from defects in the human Rab escort protein-1 (REP-1) gene. A gene targeting approach was used to disrupt the mouse chm/rep-1 gene. Chimeric males transmitted the mutated gene to their carrier daughters but, surprisingly, these heterozygous females had neither affected male nor carrier female offspring. The targeted rep-1 allele was detectable, however, in male as well as female blastocyst stage embryos isolated from a heterozygous mother. Thus, disruption of the rep-1 gene gives rise to lethality in male embryos; in female embryos it is only lethal if the mutation is of maternal origin. This observation can be explained by preferential inactivation of the paternal X chromosome in murine extraembryonic membranes suggesting that expression of the rep-1 gene is essential in these tissues. In both heterozygous females and chimeras the rep-1 mutation causes photoreceptor cell degeneration. Consequently, conditional rescue of the embryonic lethal phenotype of the rep-1 mutation may provide a faithful mouse model for choroideremia.

Alkyl and Aryl Transferases↗
PubMed1996

ERG campimetry using a multi-input stimulation technique for mapping of retinal function in the central visual field.

The m-sequence stimulation technique that has previously been described allows simultaneous recording of many local electroretinograms (ERGs). For topographical mapping of cone function in the central retina ERG traces from 61 retinal areas were recorded during a 4-min period in 20 normal volunteers and 4 patients with age-related macular degeneration, Stargardt's disease, choroidal atrophy, and polymyalgia associated with visual field loss. The local photopic luminance response was analyzed in each of the 61 areas. In the 2 patients with macular disease central defects were detected, in the remaining patients local defects were found outside the macular region. The method of multifocal ERG recordings provides the possibility of objective testing of visual fields when the outer retinal layers are affected.

Adult↗
PubMed1995

Extensive intrafamilial and interfamilial phenotypic variation among patients with autosomal dominant retinal dystrophy and mutations in the human RDS/peripherin gene.

Clinical phenotypes of patients with mutations in the human RDS/peripherin gene are described. A 67-year-old woman, who carried a 1 base pair deletion in codon 307, presented with typical late onset autosomal dominant retinitis pigmentosa (RP). In another autosomal dominant pedigree, a nonsense mutation at codon 46 caused 'inverse' retinitis pigmentosa-like fundus changes associated with progressive cone-rod degeneration in a 58-year-old man, whereas his 40-year-old son presented with yellow deposits in the retinal pigment epithelial layer resembling a pattern dystrophy, and with moderately reduced rod and cone function, as determined by two colour dark adapted threshold perimetry and electroretinography. It is suggested that both clinical pictures within this latter family may represent manifestations of fundus flavimaculatus. The clinical data of the three patients provide further evidence for the remarkable variety of disease expression within and between families with mutations in the RDS/peripherin gene. Currently, the most comprehensive statement could be that RDS/peripherin mutations are associated either with typical RP or with various forms of flecked retinal disease.

Adult↗
PubMed1995

[Social ophthalmologic aspects of retinitis pigmentosa].

Inherited retinal degenerations cause severe visual handicaps or blindness later in life. In typical rod cone dystrophy (retinitis pigmentosa) there is relevant visual loss in the third decade with implications for the patients' professional life, their mobility and their private life. For this reason, the disease is relevant for the individual patient as well as for society in general. We investigated social issues in 233 retinitis pigmentosa patients: 9.9% are not able to read any more; 40.9% have never had a driver's license and 27.8% quit driving because of a visual handicap. The mean reduction in the capacity for work is 86%; 12.7% are unable to work and therefore receive public financial support; 22.6% are unable to work in their profession; 20.9% are receiving public support because of legal blindness. Against this background it seems to be important that ophthalmologists inform their patients thoroughly about the implications of the disease for their professional and private lives. Doing this, he/she should ask for support from social service professionals.

Activities of Daily Living↗
PubMed1994

[Effect of diffractive multi-focal lenses on contrast vision, glare sensitivity and color vision].

BACKGROUND: Due to theoretical considerations an increase in the depth of field of the diffractive IOL may be combined with a reduction in contrast sensitivity, glare sensitivity and colour perception. PATIENTS AND METHODS: A comparative analysis of both eyes was performed in ten patients with a diffractive multifocal IOL (3M 815LE) in one eye and a monofocal IOL in the other eye. Contrast sensitivity was examined by computer generated sine wave gratings of 6 different spatial frequencies; visual acuity with glare and glare sensitivity were determined under 7 different levels of field luminance; colour vision was examined using the Farnsworth-Munsell-100-Hue-test. RESULTS: Contrast sensitivity of the diffractive lens was reduced for intermediate spatial frequencies, but not for low and high frequencies. Visual acuity with glare was only reduced at maximum field luminance; no differences were found in glare sensitivity and colour perception between monofocal and multifocal. CONCLUSION: Altogether, the diffractive lens did not show a dramatic reduction in the examined visual functions compared with the monofocal IOL.

Aged↗
PubMed1994

[Electroretinography study of unanesthetized young children].

BACKGROUND: The electroretinogram (ERG) ist an important examination method for the evaluation of retinal dysfunction in children. However it is often difficult and sometimes almost impossible to examine especially younger children with usual methods. Because of its risks, general anesthesia is rarely used. METHODS: ERG examinations were performed without general anesthesia or sedation with DTL (Dawson-Trick-Litzkow) electrodes. These are conjunctival electrodes made of thin microfibers. Several additional modifications of the standard examination technique were utilized, which enabled us to examine children of almost any age. 10 volunteers and 34 children between 6 month and 9 years of age were examined. RESULTS: 62 eyes of 34 children were evaluated. The diagnostic problem could be solved in three quarters of the patients with the ERG. CONCLUSION: With the DTL electrode and some methodical changes in the standard ERG technique it is possible to perform ERG's in little children without anesthesia or sedation. This method can be applied in children over 2 years of age. Below this age an sedation of any kind is necessary.

Child↗
PubMed1994

Mutation spectrum in the CHM gene of Danish and Swedish choroideremia patients.

The recent isolation of the complete open reading frame of the choroideremia (CHM) gene and the characterization of the exon-intron boundaries has paved the way to mutation detection in patients with classical choroideremia. We have performed mutation screening in patients from 15 Danish and Swedish families by using Southern blot hybridization and the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) technique. Causative mutations in the CHM gene were detected in at least 12 families, indicating that a substantial part of the mutations can be identified by this approach. In four of these families deletions of different sizes were found. Thus, in one patient, the deletion resulted in the absence of only one exon, while in another the deletion comprised the entire CHM gene. Mapping of the deletion endpoints in these four patients and in another 11 male patients with sizeable deletions enabled us to construct a very detailed map of intervals 2 and 3 of Xq21. In the remaining 11 Danish and Swedish families at least 8 causative mutations were found by PCR-SSCP analysis and direct sequencing. Interestingly, all CHM gene mutations detected thus far in choroideremia patients give rise to the introduction of a premature stop codon.

Adaptor Proteins, Signal Transducing↗
PubMed1994

Dual rod pathways in complete achromatopsia.

The vision in typical complete achromatopsia is mediated only by rods. To provide more information about the physiological basis of this disorder, we investigated in a typical complete achromat the electrophysiological correlate of the psychophysically established 15-Hz-flicker nulling phenomenon. This phenomenon is believed to be the result of destructive interference between two independent rod pathways. We obtained dark-adapted Ganzfeld electroretinogram (ERG) recordings at 15 Hz with increasing stimulus intensities in the scotopic range and compared the results of the typical complete achromat with those of a normal observer. In both observers the 15-Hz ERG signal reached a minimum at retinal illuminances associated with the perceptual null and reversed in phase as the null was traversed. In comparison with the normal observer, however, the null in the achromat was found at higher scotopic retinal illuminances (ca. 0.4 log unit). Furthermore, the loss in amplitude associated with the null was much more evident, the decline in amplitude was steeper, and the phase shift of 180 degrees was accelerated.

Color Vision Defects↗
PubMed1993

[Clinical electroretinography: standard protocol and normal values].

The International Standard of Clinical Electroretinography serves as standard protocol for recording electroretinographic responses in order to facilitate worldwide comparisons of examinations. To promote its distribution and acceptance throughout the German speaking countries, we established normal values for the five standard responses and added a German translation of the International Standard in the appendix. To determine normal values for electroretinographic data we suggest to use percentiles instead of parameters based on a Gaussian distribution. Patient-related (age, sex) and -unrelated (interstimulus-interval, diurnal rhythm) parameters proved to influence the data values significantly. With these variables taken into account one can increase the clinical value of electroretinography in terms of a greater reliability and predictiveness of data.

Adolescent↗
PubMed1993

[Developments in ophthalmologic electrophysiology].

During the last years electrophysiology in ophthalmology has been facilitated to a big extent by computerized methods. Thus it has become a suitable method for an increasing number of relevant diagnostic problems. To make comparisons between test results of different diagnostic places easier an international standard concerning the methodology of the electroretinogram (ERG) has been elaborated by the "International Society of Clinical Electrophysiology in Vision" (ISCEV). Aim of the present article is to give a short description of the ERG-standard and to review recent developments in clinical electrophysiology in ophthalmology (ca. since 1989).

Adult↗
PubMed1993

Ocular findings in a family with autosomal dominant retinitis pigmentosa and a frameshift mutation altering the carboxyl terminal sequence of rhodopsin.

A family is described in which an 8 base pair deletion (nucleotides 5252-5259, codons 341-343) of the rhodopsin gene cosegregates with autosomal dominant retinitis pigmentosa (adRP). The deletion results in a shift in the reading frame, causing a rhodopsin molecule extended by one residue and substantially altered at the carboxyl terminus. Phenotypic expression is relatively mild. In affected members, night blindness did not occur before the age of 16, and late onset of visual field loss was consistently reported. Even older individuals (59 and 76 years) had preserved central islands in the visual field; a younger female patient had normal visual fields until the age of 34. ERG and psychophysical tests showed well preserved cone function at stages of virtually abolished rod function. Phenotypic differences and similarities between this form of adRP and others associated with mutations at the carboxyl terminus of the rhodopsin molecule are discussed. The cause of RP by mutations in this region remains to be clarified.

Adult↗
PubMed1993

Efficiency of various strategies and materials to generate new markers: saturating the region 5q11.2-q13.3 with 30 new randomly distributed clones.

Several different strategies and materials were used for saturating the region 5q11.2-q13.3 with new, randomly distributed markers: isolation of human clones from three chromosome-5-specific libraries (a BssHII endclone phage library from the somatic cell hybrid H64 and two total genomic phage libraries from radiation hybrids IH12 and IH132), as well as Alu-PCR from chromosome-5-specific radiation hybrids with overlapping fragments in the region around the spinal muscular atrophy locus, followed either by direct isolation of Alu-PCR products or hybridization of Alu-PCR products to chromosome-5-gridded cosmid libraries. 253 human phage and cosmid clones were mapped to various parts of chromosome 5 by deletion mapping to somatic cell hybrid panels. 30 of these clones were mapped into the region 5q11.2-q13.3, 9 of which are flanking rate cutting BssHII-sites, known to be, often, starting points for genes. They represent excellent starting material for the development of new polymorphic markers and sequence-tagged sites, for YAC screening and building of contigs, as well as for direct isolation of genes.

Animals↗