Biomedical subjects

K Mieziewska

Publications and source records attributed to K Mieziewska.

7 recordsLinked to original sources

PubMed1996

The interphotoreceptor matrix, a space in sight.

The interphotoreceptor matrix (IPM) has in recent years been receiving much attention due to its delicate localization between the photoreceptors and the retinal pigment epithelium (RPE). The IPM is a resilient, structure forming and hydrophilic matrix composed of large glycoproteins and proteoglycans, which occupies the subretinal space between the photoreceptors. The IPM is most likely assembled with components synthesized by all the surrounding cell types: the photoreceptor cells, the RPE cells, and the Müller cells. It has been implied to be involved in the development and maintenance of photoreceptors, and as a major factor in retinal adhesion. Therefore, it has been thoroughly studied also in several models of photoreceptor degeneration. Comparative studies have revealed some remarkably consistent features between different species, such as the presence of the rod and cone specific matrix domains. Studies made in the IPM of several species have measured large fluctuations in ion concentrations as a result of changes in illumination. In some species, these ionic fluctuations coincide with the intriguing dynamic redistributions of IPM constituents that can be visualized with histochemical techniques. It can be hypothesized that because of the intensive biochemical activity and the frequent changes in metabolic states of rods and cones the IPM may act as a kind of "buffer." These studies have brought a new extracellular aspect to photoreceptor studies and a new perspective to photoreceptor-RPE research.

Animals↗

PubMed1994

Redistribution of insoluble interphotoreceptor matrix components during photoreceptor differentiation in the mouse retina.

The development of the nervous system is largely influenced by the extracellular matrix (ECM). In the neural retina, the photoreceptors are surrounded by a unique ECM, the interphotoreceptor matrix (IPM). The IPM plays a central and possibly crucial role in the development, maintenance and specific function of the photoreceptors. Therefore, the characterization of IPM components is necessary to understand the mechanisms regulating photoreceptor differentiation. The IPM in the mouse retina was examined during photoreceptor morphogenesis with the monoclonal antibody (MAb) F22, which recognizes a 250 kDa component of the interphotoreceptor matrix. The binding pattern of MAb F22 revealed a striking redistribution in the expression of the 250 kDa F22 antigen in late stage of postnatal photoreceptor differentiation in the mouse retina. The F22 staining was detectable in the IPM around the inner segments on the third postnatal day (P3). The MAb F22 initially labeled the region around inner segments, but as the outer segments elongated, the F22 distribution became concentrated to the matrix around the rod and cone outer segments until P16-17. At P17, the F22 label around rods began to disappear, while the label around cones became more defined. The shift in label distribution was largely completed by P20. Residual rod-associated label disappeared within a few days. In the adult animal, the F22 antibody labeled the cone-associated matrix only, and this labeling pattern remained stationary. The change in the distribution of MAb F22 demonstrated by immunolabeling was not accompanied by changes in the size of the molecule; F22 antigen isolated from the IPM of P13-15, and from adult IPM migrated with the same molecular weight on SDS gels. The distribution of MAb F22 was compared to that of chondroitin sulfate proteoglycans which are abundant in the IPM. The labeling patterns of MAbs CS-56, C6-S and C4-S were distinct from that of MAb F22. A general decrease of the label intensity was seen with two chondroitin sulfate MAbs (CS-56 and C4-S) between 16 days and 4 months, but a total loss of rod-associated label was not observed. All three chondroitin sulfate MAbs labeled the retina at embryonic day (E) 11.5-13.5, a time of outgrowth of ganglion cell axons, but the F22 antigen was not detected in the retina at this stage of development. The results demonstrate that the F22 and the chondroitin sulfate antibodies are recognizing different molecules that have distinct roles in retinal morphogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1994

Interphotoreceptor matrix components in retinal cell transplants.

To further investigate the functional potential of retinal transplants we have used immunocytochemistry to study the distribution of four different interphotoreceptor matrix (IPM)-specific components in rabbit retinal transplants. The different components were: interphotoreceptor retinoid-binding protein (IRBP), chondroitin-6-sulfate, F22 antigen and peanut agglutinin (PNA) binding structures. IRBP acts as a retinoid-transport protein between the neural retina and the retinal pigment epithelium. Chondroitin-6-sulfate is a glycosaminoglycan and a part of the insoluble IPM skeleton. The identity and role of the F22 antigen is not known. However, it is a 250 kDa protein localized to specific extracellular compartments such as teh IPM. PNA is a lectin with a high binding affinity for D-galactose-beta (1-3) N-acetyl-D-galactosamine disaccharide linkages and binds to IPM domains surrounding cones, but not rods. The transplants (15-day-old embryonic rabbit retina) were placed between the neural retina and retinal pigment epithelium in adult hosts. The transplants developed the typical rosette formations with photoreceptors toward the center. IRBP labeling was distinct in the IPM in the host retina. However, no IRBP labeling could be detected in the transplants. The chondroitin-6-sulfate and F22 antibodies strongly labeled the IPM in the host retina and corresponding structures in the center of rosettes. A cone-specific labeling with PNA could be seen in the host retina. In the transplants, however, PNA labeling appeared in association with many more photoreceptors than in the host retina. There is no previous study available on the IPM in retinal cell transplants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Spatial and temporal differences between the expression of short- and middle-wave sensitive cone pigments in the mouse retina: a developmental study.

In an earlier study we found a topographic separation of middlewave-sensitive (M) and shortwave-sensitive (S) cones in the adult mouse retina. In the present study we investigated the development of the two colour-specific cone types to see whether there is also a temporal difference between the expression of the specific cone visual pigments. Using two anti-cone visual pigment antibodies, COS-1 and OS-2, we compared the densities of immunopositive cone outer segments on retinal whole mounts derived from mice of various ages. The first detectable cone outer segments were the S-cones which appeared in the inferior half of the retina on postnatal day 4. At this stage, the density of the S-cones was very low (30-40 cones/retina) but increased steadily on the following days to reach a value comparable to that of adults by P30 (18,000/mm2). This cone type always remained much more abundant in the lower part of the retina throughout the whole retinal development. In the superior half of the retina, a few S-cones appeared from postnatal day 7; however, their number always remained about one order of magnitude lower than in the inferior part. In contrast, M-cone outer segments were not identifiable earlier than postnatal day 11 and were confined exclusively to the superior part of the retina during the whole developmental process. On postnatal day 12, their density was 1,900/mm2 and increased to a value of 11,000/mm2 by postnatal day 30, which represented the adult stage. As shown by comparison of isodensity lines derived from immunocytochemical reactions of whole mount retinas, the two cone types occupied complementary halves of the mouse retina with maximum density centres located in opposite retinal quadrants. We conclude that 1) in contrast to the primate retina, mouse S-cones precede the M-cones in their development, and 2) the spatial arrangements of the two cone types is maintained throughout the whole differentiation process.

Animals↗

PubMed1993

Development and fate of interphotoreceptor matrix components during dysplastic photoreceptor differentiation: a lectin cytochemical study of rod-cone dysplasia 1.

The autosomal recessive retinal degeneration rod-cone dysplasia 1 (rcd1) affects Irish setter dogs during early postnatal development. The disease is the result of a cyclic guanosine monophosphate metabolic abnormality and morphological evidence of disease onset correlates with initiation of photoreceptor outer segment formation. Rod photoreceptors are affected earlier and more severely than cones. Postnatal development of specific interphotoreceptor matrix (IPM) constituents was examined in tissue sections and extracted matrix preparations from control and affected dogs using peanut agglutinin (PNA) and wheat germ agglutinin (WGA) lectin cytochemistry. These lectins bind two photoreceptor-specific domains through their affinity for specific terminal carbohydrate sequences present on proteoglycans and glycoproteins in the IPM. Development of rod and cone matrix domains in the normal dog occurs in parallel to the development and differentiation of outer segments (between postnatal days 10 and 60 in the dog); during this period the lectin specificity or distribution in the rcd1 retina did not differ from the normal control. Structural changes of the matrix domains were present and reflected the morphological alterations of the diseased and degenerating photoreceptor cells. Cone domains were present around severely degenerated cone cells as long as these cells were found within the interphotoreceptor space. The matrix domain investing surviving cones did not differ significantly from the normal to indicate an altered binding specificity or structure. The rod domain was still present around rod inner segments in late degeneration. The matrix domains are present in the IPM as long as the photoreceptor cell body remains in the interphotoreceptor space; photoreceptor loss results in disappearance of the matrix. We detected no change in matrix composition or distribution with the lectins used, either during development or degeneration, despite the serious biochemical and structural abnormalities of the photoreceptor cell that are characteristic of the disease.

Aging↗

PubMed1993

Diethylene glycol distearate (DGD): a versatile embedding medium for retinal cytochemistry.

Embedment in diethylene glycol distearate (DGD) was shown to be highly desirable and versatile for retinal cytochemical studies, including in situ hybridization, immuno- and lectin cytochemistry. This method allows for preservation of fine tissue detail as well as good reaction sensitivity. It appears to be more suitable than most other methods currently used for light microscopic retinal cytochemistry.

Animals↗

PubMed1993

Structural changes of the interphotoreceptor matrix in an inherited retinal degeneration: a lectin cytochemical study of progressive rod-cone degeneration.

PURPOSE: In the retinal disorder progressive rod-cone degeneration (prcd) in miniature poodle dogs, the photoreceptor layer degenerates slowly in the course of 5 to 7 years. Components of the interphotoreceptor matrix form a continuous extracellular lattice around photoreceptors. The purpose was to study the photoreceptor cell-matrix interactions during the disease and degeneration phases. Because degeneration rate was slower in cones, the authors also wanted to investigate whether there was a link between the degeneration and the photoreceptor-specific interphotoreceptor matrix domains. METHODS: Rod- and cone-specific interphotoreceptor matrix domains were examined during two periods: before morphological signs of disease had appeared and during the degenerative stages. Two lectin probes were used; wheat germ agglutinin and peanut agglutinin. By their affinity for terminal carbohydrates, the lectins visually separated the two photoreceptor-specific domains and allowed follow-up of the fate of the rod and cone matrices separately. RESULTS: Before and during the course of disease, the lectin distribution in rod and cone domains remained normal, however, in the degenerative phase of the disease, there were structural changes in the matrix domains. The matrix connections between the individual domains was disrupted and single domains were formed. Cone domains and, to a lesser degree rod domains, were thickened around the inner and outer segments. CONCLUSIONS: The changes occurring in the photoreceptor-specific domains were indicative of structural adaptation to cell death and to degenerative conditions. There was no evidence of an active involvement of the interphotoreceptor matrix components studied in the disease process.

Animals↗