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Biomedical subjects

B Ehinger

Publications and source records attributed to B Ehinger.

At least 91 records · Page 5Linked to original sources
PubMed1992

Transplantation of embryonic retina to the subretinal space in rabbits.

Embryonic rabbit retina can be transplanted to the subretinal space of adult rabbit with a new method, which gives a high rate of successful short-term transplants. Embryonic (stage E 15) neural retina cells were injected through an incision just behind the sclerocorneal border with a thin (inner diameter 0.15-0.4 mm, outer diameter 0.3-0.5 mm) plastic tube attached to a specially designed instrument, by which the length of the protruding plastic tip could be controlled. The retina was penetrated from the vitreous side and the donor tissue was injected into the subretinal space. The cells survived in the host for at least 5 months, although the long-term survival rate tended to decrease. The transplanted cells matured and differentiated, forming an approximation of the layered, retinal structure with some anomalies (e.g. rosettes). The subretinal location offers an interesting and convenient way of studying the development of retinal cell transplants in rabbits. Large transplants can be produced, and the risk for failures due to erroneous vitreous placement is small.

Animals↗
PubMed1992

Serum transferrin in patients with retinitis pigmentosa.

The CDG syndrome is a newly detected disorder with a carbohydrate defect in glycoproteins such as transferrin. As retinitis pigmentosa is a part of this syndrome, there could also be other subtypes of retinitis pigmentosa with a similar biochemical defect. Isoforms of serum transferrin were therefore analysed in 78 patients from different families with retinitis pigmentosa and showed slightly or moderately elevated values for less glycosylated isoforms in two families. The study suggests that abnormal glycoprotein metabolism manifested by elevated values of carbohydrate-deficient isotransferrins may be present in a small proportion of families with retinitis pigmentosa. The relationship between the glycoprotein defect and retinitis pigmentosa remains to be established.

Adult↗
PubMed1992

A six-generation family with autosomal dominant retinitis pigmentosa and a rhodopsin gene mutation (arginine-135-leucine).

This study documents the ophthalmological findings in a six-generation. Swedish family with autosomal dominant retinitis pigmentosa with a previously unknown rhodopsin, exon 2, mutation, Arg-135-Leu (CGG to CTG). Six affected patients from the family were available for analysis and were all found to be heterozygous for the mutation, whereas eight clinically normal family members and 29 unrelated normal individuals did not have it. The disease appears to be of a type with comparatively rapid progression to blindness.

Adult↗
PubMed1992

[Current diagnostic and therapeutic possibilities in tapetoretinal degeneration].

Recent advances in research have markedly improved the possibility of differentiating between the different kinds of retinitis pigmentosa, and of elucidating prognosis, heredity and in certain cases the precise pathogenesis. Although treatment trials have begun, as yet no adequate treatment is available for the majority of patients with diseases belonging to this category. One approach under discussion is transplantation of fetal retinal cells.

Animals↗
PubMed1991

Full-field electroretinograms in patients with the carbohydrate-deficient glycoprotein syndrome.

We examined five patients who had carbohydrate-deficient glycoprotein syndrome with full-field electroretinograms. Only two of the patients showed fundus changes typical for retinitis pigmentosa, whereas abnormal electroretinograms were seen in all patients. There was no recordable rod response; however, a delay in the cone b-wave implicit time was noted. All patients had nyctalopia. These observations suggest that patients with the carbohydrate-deficient glycoprotein syndrome have a progressive tapetoretinal degenerative disorder of the retinitis pigmentosa type with defined alterations in the electroretinogram.

Adolescent↗
PubMed1991

Photoreceptor degeneration and loss of immunoreactive GABA in the Abyssinian cat retina.

GABA (gamma-amino butyric acid) and its synthesizing enzyme, GAD (glutamate decarboxylase; EC 4.1.1.15) were localized in the retina of Abyssinian cats homozygous for a recessively inherited retinal degenerative disorder which in several respects is similar to the human disease, retinitis pigmentosa. Clinically normal mongrel cats and heterozygous Abyssinian cats were studied for comparison. The GABA and GAD immunoreactive neurons of the heterozygous or young homozygous (clinically unaffected animals) had the same distribution and morphology as normal mongrel European type cats. The neuronal GABA immunoreactivity in both the inner and outer parts of the retina gradually disappeared in the course of the disease, with little or no loss of GAD immunoreactive neurons. Early in the disease, the changes were most severe in patches in the mid periphery of the eye and then spread both centrally and peripherally. Loss of photoreceptors was a prerequisite for the loss of GABA immunoreactivity. The observations show that retinal changes are not limited to the photoreceptors. The GABA loss is not likely to be due to a loss of neurons, because of the persistence of GAD immunoreactive neurons.

Animal Husbandry↗
PubMed1991

Ultrastructure of human retinal cell transplants with long survival times in rats.

Human fetal retinas (6-12 weeks post-conception) were obtained from elective abortions, transplanted to rat retinas and examined by electron microscopy. The oldest transplants that form the basis of this report were obtained 40 and 41 total weeks post-conception. The host rats were immunosuppressed with cyclosporin A. The transplants developed according to their intrinsic, genetically determined timetable. The development was heterogeneous with some parts showing almost normal differentiation and others, little. Both rods and cones developed with inner and outer segments and synaptic terminals. In regions corresponding to the inner plexiform layer, bipolar cell processes were seen in the typical dyad arrangement. Likewise, amacrine cell processes formed typical conventional synapses. Serial synapses were seen, engaging amacrine cell synapses as well as a few reciprocal synapses at the bipolar cell dyads. Monad-type synaptic complexes, a sign of immaturity, were common in bipolar cell processes. Similarly, incompletely differentiated synapses of both the amacrine and bipolar cell types were often observed. Ganglion cell processes could not be identified with certainty. A structure with morphological characteristics similar to the inner limiting membrane was noted to form inside the transplant. Both epi-retinal and sub-retinal transplants were obtained. Transplant cells touched host photoreceptor cells or pigment epithelium without any obvious specializations. The host pigment epithelium microvilli were absent adjacent to the graft. However, graft cells did appear in the host retina, and nerve cell processes were observed to cross the membrane separating the transplant and host.

Animals↗
PubMed1991

Characterization of neuropeptide Y-like immunoreactivity in vertebrate retina.

We have determined the endogenous levels of neuropeptide Y-like immunoreactivity (NPY-LI) in retinal extracts from pigs, cats, rabbits, chickens, and frogs by radioimmunoassay (RIA). The NPY-LI levels varied among the species. The highest concentration was found in frog retina, where seasonal variations were seen, 861 +/- 31 pmol g(-1) wet weight in the autumn and 334 +/- 26 pmol g(-1) wet weight in the spring. Lower levels were demonstrated in chicken and pig retina, 4.1 +/- 0.4 and 3.6 +/- 0.3 pmol g(-1) wet weight, respectively. The lowest concentration was demonstrated in rabbit retina, 2.0 +/- 0.3 pmol g(-1) wet weight. (All values are expressed as mean +/- S.E.M.). The NPY-LI in pig, rabbit, chicken and frog retina was characterized by high-performance liquid chromatography (HPLC). The main part of the extracted NPY-LI had an elution volume close to that to the porcine NPY. We have also analysed the evoked release of endogenous NPY from frog retina, induced either with light flashes (3 Hz, 300 lx), or with potassium depolarization of the neurons (40 mM). Light flashes and potassium induced an increased release of NPY-LI of 61 and 77%, respectively. NPY-LI in the efflux had the same HPLC retention time as that extracted directly from the retina.

Animals↗
PubMed1991

Intraocular microdialysis with permanently implanted probes in rabbit.

The technique of microdialysis in vivo, much used in brain experiments, has been adapted for intraocular use. A new probe was designed, made from a soft tube with the dialysis membrane mounted in a fenestrated protecting sleeve, facing one side. A special surgical procedure was developed for the long-term implantation of the probes. They stay functional in the eyes for several weeks or more. Previously published intraocular microdialysis studies were short-term experiments. The acute surgical trauma is likely to affect the concentration of many compounds in the vitreous, and this effect is minimized with long-term probes.

Amino Acids↗
PubMed1990

Neuronal markers in rat retinal grafts.

Rat E15 retina was grafted to the retina of adult rat hosts. After varying survival times (1 week-6 months), grafts were stained by immunohistochemistry for neurofilament 160 kDa (NF), HPC-1 (an amacrine cell marker), choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), glutamic acid decarboxylase (GAD) and somatostatin-28 (SS-28). The first differentiating graft amacrine cells (cholinergic and dopaminergic) could be seen 1 week after transplantation (corresponding to postnatal day 1 = P1). The inner plexiform layer of the graft started to differentiate at 2 weeks (corresponding to P8) seen by HPC-1 and GAD staining. ChAT, TH and SS-28 immunostaining revealed an abnormal lamination pattern in the graft inner plexiform layer. Also by 2 weeks, the outer plexiform layers of the graft contained NF-immunoreactive horizontal cells. No NF-stained retinal ganglion cells could be observed in the graft. Five and 7 weeks after grafting, the transplants had obtained the same staining intensity with different markers as the host retina.

Animals↗
PubMed1990

Electroretinographic diagnosis in families with X-linked retinitis pigmentosa.

Four families with X-chromosome linked retinitis pigmentosa (14 patients, 14 carriers and 11 normal relatives) were investigated with full-field ERG with computer averaging and an electronic narrow bandpass filter. Reliable ERGs were obtained with 30 Hz flickering white light from 13 out of 14 patients with the disease, all severely affected. Further, B-wave implicit times were found to be more informative than B-wave amplitudes for identifying carriers of the disease. Full-field ERG appears to be a valuable tool for studying X-chromosome linked retinitis pigmentosa families, when necessary supported with computer averaging and a narrow bandpass filter.

Computer Systems↗
PubMed1990

Postnatal development of photoreceptor-specific proteins in mice with hereditary retinal degeneration. An immunocytochemical study.

The postnatal development of immunoreactivity for photoreceptor-specific markers was studied in mice carrying the genes rd (retinal degeneration) and rds (retinal degeneration slow) in different combinations. Antibodies raised against three specific photoreceptor proteins (opsin, alpha-transducin and S-antigen) were applied on retinae from mice with the following allelic combinations at the rd and rds loci: +/+, +/+ (control); rd/rd, +/+; rds/rds, +/+; rds/+, +/+; and rd/rd, rds/rds. Immunoreactivity for each antibody appeared simultaneously in normal and mutants. Thereafter, the immunoreactivity patterns in the mutants diverged from the normal phenotype. Except for a dramatic loss of photoreceptor cells in the mutants, the main divergence from the normal development consisted of a progressive loss of the intracellular immunoreactivity compartmentalization for each protein. As degeneration progressed, the remaining photoreceptors became homogeneously labelled; one this labelling pattern was acquired, it was maintained during subsequent stages of development. It is proposed that this pattern, common for all phenotypes studied, may be due to the loss of structural and biochemical polarity of the photoreceptor cells undergoing degeneration, and that this may be an important primary or secondary aspect of the disease process.

Animals↗
PubMed1988

Bipolar cells in the turtle retina are strongly immunoreactive for glutamate.

Strong glutamate immunoreactivity was observed by both light and electron microscopy in bipolar cells of the turtle (Pseudemys scripta elegans) retina after postembedding immunohistochemistry. Virtually all bipolar cells showed strong labeling, on average 18 times that of the Müller (glial) cells. The data suggest that both on- and off-center bipolar cells are glutamatergic. Photoreceptors were also labeled, but with a labeling intensity about half that of the bipolar cells. Other types of retinal neurons showed less immunoreactivity, except for a small population of strongly labeled amacrine cells.

Animals↗