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Biomedical subjects

A Eckstein

Publications and source records attributed to A Eckstein.

30 records · Page 2Linked to original sources
PubMed1995

The renin-angiotensin system--a possible neuromodulator in the human retina?

Morphology studies imply a possible contribution of the renin-angiotensin system (RAS) to neurotransmission in the mammalian retina. To investigate further the functional role of the RAS in the visual system of humans, we tested the effects of the angiotensin-converting enzyme (ACE) inhibitor Captopril (Capt; 25 mg) on electroretinogram (ERG) recordings, the cone flicker threshold (CFT), the FM-28-HUE test, and the psychophysical rod threshold in healthy volunteers. The parameters of renin, angiotensin, and blood pressure were controlled. We obtained the following results. First, Capt induced a significant decrease in amplitudes of the scotopic b-wave, oscillatory potentials, and the a-wave. The latency of responses to 30-Hz flicker was increased. Second, the CFT was reduced to a lower intensity, whereas the final rod threshold remained unchanged. These results are in accordance with previous immunocytochemical and electrophysiological data. They cannot be explained exclusively by the observed changes in systemic blood pressure. We conclude that the RAS may possibly be involved in retinal neurotransmission in humans in addition to its vascular effects.

Administration, Oral↗
PubMed1995

Colour contrast sensitivity in patients with age-related Bruch's membrane changes.

Patients with bilateral drusen as a manifestation of early age-related macular degeneration (AMD) may have minor psychophysically detectable visual defects in the presence of normal visual acuity. In a variety of retinal diseases, one of the earliest changes in visual processing is an impairment of normal colour vision. This study was undertaken to evaluate colour vision deficits in patients with macular drusen and to determine whether changes in colour contrast sensitivity may occur over time. In a prospective study, colour vision in 84 eyes of 84 patients aged 55-84 years (mean, 68.89 +/- 6.23 years) with macular drusen and clear media was tested using a computer graphics technique. A total of 47 patients were reviewed annually for up to 2 years and measurements were obtained at annual intervals. Colour contrasts sensitivity along protan, deutan and tritan colour confusion lines was determined at a foveal and a parafoveal region. The sensitivity to all stimuli showed large variations between patients. The thresholds for foveal blue-colour contrast sensitivity were elevated and increased during the review period. In contrast, there was no significant change in sensitivity with time for red and green at the foveal or parafoveal region. Tritan threshold changes suggest that the SW cone-receptor population is more susceptible to damage associated with early age-related macular disease than are red or green cones. The results indicate that blue colour contrast sensitivity determined over time may serve as a measure to assess the progression of age-related maculopathy prior to the manifestation of atrophic or exudative macular lesions associated with visual loss.

Aged↗
PubMed1994

Macular dystrophy associated with mutations at codon 172 in the human retinal degeneration slow gene.

BACKGROUND: Recently, mutations in the retinal degeneration slow (rds) gene which codes for peripherin-rds have been implicated as a cause of autosomal dominant retinitis pigmentosa. Because this gene is expressed in both rods and cones, mutations in the rds gene might be expected to cause degeneration affecting either the scotopic or photopic systems. Mutations at codon 172 of the rds gene have been identified in three families with autosomal dominantly inherited, progressive macular dystrophy. METHODS: Affected individuals underwent ophthalmic examination, scotopic perimetry, dark adaptometry, measurement of color-contrast sensitivity, and electroretinography to characterize the photoreceptor dysfunction. RESULTS: In all but one affected member, symptoms of progressive central visual loss developed in the third or fourth decade of life accompanied by central scotoma and well-demarcated atrophy of the retinal pigment epithelium and choriocapillaris of the macula. In general, cone and rod thresholds were elevated, and color-contrast sensitivity was absent in the central visual field. Peripherally, the scotopic sensitivities were normal, as was the recovery from bleach. Cone electroretinograms were diminished in amplitude, and delayed in all affected adults except one. Rod electroretinograms were normal or near normal in amplitude, and had normal implicit times. Affected asymptomatic children had macular changes, abnormal color-contrast sensitivity, and reduced pattern and cone electroretinograms. CONCLUSION: These results indicate that mutations in the rds gene can be expressed as a macular dystrophy, with evidence of primary cone dysfunction and preservation of peripheral rod function.

Adolescent↗
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

Ocular findings associated with a 3 base pair deletion in the peripherin-RDS gene in autosomal dominant retinitis pigmentosa.

Affected members of a family with autosomal dominant retinitis pigmentosa were found to have a 3 base pair deletion at codon 118 or 119 of the retinal degeneration slow gene. This mutation causes the loss of a highly conserved cysteine residue in the predicted third transmembrane domain of peripherin-rds, a photo-receptor specific structural glycoprotein localised to both rod and cone outer segment disc membranes. Four of these individuals underwent detailed clinical, psychophysical, and electroretinographic testing in order to characterise their photoreceptor dysfunction. Nyctalopia was reported early in the second decade by all patients. Global rod and cone dysfunction was recorded by the third decade with severe reduction of both photopic and scotopic function by age 30 years. This retinal degeneration slow gene mutation may lead to the primary loss of both rod and cone photo-receptor function.

Adult↗
PubMed1993

Mutations in the human retinal degeneration slow (RDS) gene can cause either retinitis pigmentosa or macular dystrophy.

Mutations in the RDS gene, which encodes the photoreceptor glycoprotein peripherin, have been sought in families with autosomal dominant retinal dystrophies. A cysteine deletion at codon 118/119 is associated with retinitis pigmentosa in one. Three families with similar macular dystrophy have mutations at codon 172, arginine being substituted by tryptophan in two and by glutamine in one. A stop sequence at codon 258 exists in a family with adult vitelliform macular dystrophy. These findings demonstrate that both retinitis pigmentosa and macular dystrophies are caused by mutations in RDS and that the functional significance of certain amino-acids in peripherin-RDS may be different in cones and rods.

Adult↗
PubMed1992

Multiple-stimulus presentation and voice control in automated perimetry.

In all, 55 eyes of 55 patients were examined prospectively in random order with the Humphrey field analyzer [central field 76 points, full threshold strategy, single-stimulus presentation, response-button control (HFA 1); central field 76 points, defect-depth strategy, response-button control (HFA 2)] and the Dicon TKS-4000 [central field 76 points, defect-depth strategy, multiple-stimulus presentation, response-button control (DIC 1); central field 76 points, defect-depth strategy, multiple-stimulus presentation, voice control (DIC 2)]. Some 26 patients (47%) had glaucomatous field defects, 7 patients (13%) had lesions of the visual pathway, 5 patients (9%) had normal fields. The other 17 patients (31%) had field defects due to vascular lesions of the retina or the optic nerve, retrobulbar neuritis, cataract, dysthyroid optic neuropathy, disorders of the macula, or human immunodeficiency virus (HIV) retinopathy. The mean testing time for the whole study population was 5.2 +/- 2.7 min for DIC 1. The difference from the mean testing time for HFA 2 (6.4 +/- 2.7 min) is statistically significant (p = 0.0013). DIC 2 reduces the mean testing time to 4.9 +/- 2.6 min. The difference from DIC 1 is not statistically significant (p = 0.8110). A multiple-stimulus presentation and voice control seem to be useful methods to reduce the testing time in automated perimetry without a loss of accuracy. Voice control, as used in the DICON TKS 4000, still has to be improved, however.

Adult↗
PubMedDate not supplied

[Genuine ossification of cleft jaws in bilateral total clefts of the lip, jaw and palate].

Report on the treatment of a female patient, now 18 years old, with a bilateral continuous cleft of the lip, jaw and palate, in whom genuine ossification occurred at the jaw clefts. The upper lateral incisors and both upper canines have aligned themselves regularly in this jaw. Until now natural bone formation in a cleft jaw has been considered impossible.

Adolescent↗