Pancreata of normoglycemic diabetes-prone (dp) and diabetes-resistant (dr) BB rats and normal Wistar rats were screened for macrophage infiltration by immunohistochemistry and by electron microscopy. Inflammatory macrophages were found in... more
Pancreata of normoglycemic diabetes-prone (dp) and diabetes-resistant (dr) BB rats and normal Wistar rats were screened for macrophage infiltration by immunohistochemistry and by electron microscopy. Inflammatory macrophages were found in the endocrine as well as the exocrine part of the pancreata from dp BB rats. In the exocrine tissue they had a different phenotype (ED1+, ED2+, W3/25+, Ox17+) from that found in pancreata from dr BB and Wistar rats (predominantly ED1-, ED2+, W3/25+, Ox17-). The number of macrophages in exocrine portions of pancreata from the various rat strains were not different. By electron microscopy scattered macrophage-associated tissue lesions and phagocytosis of cell debris were found throughout the exocrine tissue and in islets of dp BB rats. Such lesions were low or absent in biopsies of animals that later did not develop diabetes. We conclude that macrophage-mediated cytotoxicity during the early phases of diabetes development in BB rats is not restricted to islets, but is a generalized, pan-pancreatic event.
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In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome.... more
In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome. Granules having a homogeneous matrix also function as premelanosomes. The presence of acid phosphatase reaction product inside the melanin granules indicated that these organelles in this animal were also related to lysosomes. DOPA-oxidase of tyrosinase, the key enzyme in melanogenesis, was surprisingly not only detected in melanocytes but also in the Golgi stacks of dermal cells. Due to the mechanisms of premelanosome formation it is evident that cytoplasmic material also serves as substrate for melanogenesis. EDX microanalysis was performed to measure the ionic composition of the melanin granules. After aldehyde fixation the newly-formed melanin granules did not contain Na, but had accumulated Ca.
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Our aim was to generate and phenotypically characterize a transgenic mouse line expressing a constitutively active variant of the transcription regulatory protein serum response factor (SRF), namely the SRF-VP16 protein. This new mouse... more
Our aim was to generate and phenotypically characterize a transgenic mouse line expressing a constitutively active variant of the transcription regulatory protein serum response factor (SRF), namely the SRF-VP16 protein. This new mouse strain has been registered under the designation Gt(ROSA)26Sor(tm1(SRF-VP16)Antu). We found phenotypic changes upon ectopic expression of SRF-VP16, especially in the mouse retina. Using homologous recombination, we integrated an SRF-VP16 conditional (i.e., "flox-STOP" repressed) expression transgene into the Rosa26 locus of murine embryonic stem (ES) cells. These engineered ES cells were used to derive the Gt(ROSA)26Sor(tm1(SRF-VP16)Antu) mouse strain. Semiquantitative real-time PCR was used to determine expression of the SRF-VP16 transgene at the mRNA level, both in young (P20 and P30) and adult (six months old) Gt(ROSA)26Sor(tm1(SRF-VP16)Antu) mice. We also investigated the transcript levels of endogenous Srf and several SRF target genes. ...
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To determine the effects of the vascular endothelial growth factor (VEGF)-A(165) delivered using a high capacity adenoviral vector (HC Ad.VEGF-A) on vascular growth and pathological changes in the rabbit eye. To combine different... more
To determine the effects of the vascular endothelial growth factor (VEGF)-A(165) delivered using a high capacity adenoviral vector (HC Ad.VEGF-A) on vascular growth and pathological changes in the rabbit eye. To combine different detection methods of VEGF-A(165) overexpression-induced neovascularization in the rabbit. HC Ad.VEGF-A(165) was constructed and injected at 5 x 10(6) infectious units (iu) into the subretinal space of rabbit eyes. Two and four weeks postinjection, the development of neovascularization and the expression of HC Ad-transduced VEGF-A(165) protein were followed up in vivo by scanning laser ophthalmoscopy, fluorescein and indocyanine green angiographies and ex vivo by electron microscopy and immunohistochemistry We observed a choroidal neovascularization (CNV) with leakage in 83% of the rabbit eyes. Our findings present clear indications that there is a significant effect on the endothelial cells of the choriocapillaris after subretinal transduction of the retina...
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Many medications that are administered systemically for nonocular conditions may evoke ocular toxicological complications. Therefore, the eye is routinely investigated histopathologically in preclinical in vivo toxicity studies. The... more
Many medications that are administered systemically for nonocular conditions may evoke ocular toxicological complications. Therefore, the eye is routinely investigated histopathologically in preclinical in vivo toxicity studies. The retinal pigment epithelium is a likely target for systemically administered compounds, since the underlying choroid is highly vascularized. The specialized pigment epithelium has numerous functions that all maintain the integrity and function of photoreceptors. Consequently, toxic effects on the pigment epithelium will eventually affect the neural retina. The potential of pigment epithelial cells to respond to toxic injury is limited, but a standardized terminology to describe its morphological changes does not exist in the scientific literature. Detailed morphologic analysis, however, might allow early detection of retinotoxicity and may provide evidence on the underlying pathomechanism. We here review toxic effects on the pigment epithelium focusing in...
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The Royal College of Surgeons (RCS) rat is an animal model for retinal degeneration such as the age-related macular degeneration. The RCS rat undergoes a progressive retinal degeneration during the early postnatal period. A potential... more
The Royal College of Surgeons (RCS) rat is an animal model for retinal degeneration such as the age-related macular degeneration. The RCS rat undergoes a progressive retinal degeneration during the early postnatal period. A potential treatment to prevent this retinal degeneration is the transplantation into the subretinal space of cells that would replace functions of the degenerating retinal pigment epithelium (RPE) cells or may form neurotrophic factors. In this study we have investigated the potential of subretinally transplanted embryonic stem cells to prevent the genetically determined photoreceptor cell degeneration in the RCS rat. Embryonic stem cells from the inner cell mass of the mouse blastocyst were allowed to differentiate to neural precursor cells in vitro and were then transplanted into the subretinal space of 20-day-old RCS rats. Transplanted and sham-operated rats were sacrificed 2 months following cell transplantation. The eyes were enucleated and photoreceptor deg...
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Localization of light-induced lipid peroxides in the rat retina at an ultrastructural level as benzidine-reactive substances. Long-Evans rats with nondilated pupils were exposed to intense light of 6000 lux for 12 or 24 hours. Control... more
Localization of light-induced lipid peroxides in the rat retina at an ultrastructural level as benzidine-reactive substances. Long-Evans rats with nondilated pupils were exposed to intense light of 6000 lux for 12 or 24 hours. Control animals were kept under physiological light conditions. Rats with dilated pupils were exposed to a light intensity of 50 lux or 150,000 lux for 1 hour. For ultrastructural localization the enucleated eyes were fixed in a 0.1-M cacodylate buffer (pH 7.4) containing 2% glutaraldehyde for 2 hours. Pieces of the superior part of the central eyecup were incubated overnight with tetramethylbenzidine (TMB; pH 3.0) at 4 degrees C, postfixed with 1.5% OSO4, and embedded for electron microscopy. In animals exposed to intense light, electron-dense structures appeared exclusively throughout the rod outer segments after an irradiation of 6000 lux for 24 hours or 150,000 lux for 1 hour and were absent in animals with nondilated pupils kept at physiological light con...
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The aim of this study was to investigate the possible rescue effect of subretinal iris pigment epithelial (IPE) cell transplantation in Royal College of Surgeons (RCS) rats by light and electron microscopic histology. IPE cells were... more
The aim of this study was to investigate the possible rescue effect of subretinal iris pigment epithelial (IPE) cell transplantation in Royal College of Surgeons (RCS) rats by light and electron microscopic histology. IPE cells were harvested from 20- to 26-day-old Long-Evans rats and were directly trans planted transsclerally into the subretinal space of 32 16- to 20-day-old RCS rats using a 32-gauge Hamilton syringe. Specimens of transplanted eyes were embedded for electron microscopy after 8 weeks. Specimens from the iris and retinal pigment epithelium (RPE) of Long-Evans rats and RPE from RCS rats without surgical treatment were also embedded. Sham surgery was also performed in 8 eyes. The IPE cells transplanted into the subretinal space were localized between host RPE and retina, had round cell shapes without polar organization, and contained phagosomes resulting from rod outer segment (ROS) uptake. The underlying host RPE cells were heavily pigmented. RPE cells from RCS rats r...
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Because earlier studies indicate that the choroid close to the ora serrata may have unique anatomic features such as wandering cells, blood vessels in Bruch's membrane, and accumulated pigment in the retinal pigment epithelium (RPE),... more
Because earlier studies indicate that the choroid close to the ora serrata may have unique anatomic features such as wandering cells, blood vessels in Bruch's membrane, and accumulated pigment in the retinal pigment epithelium (RPE), the morphology of the normal human eye at the ora serrata region was investigated. Specimens from the ora serrata region of two normal human eyes (male donors, 48 and 52 years old) were investigated by light and electron microscope. Specimens from all quadrants were studied in one eye. The elastic layer of Bruch's membrane extended as far as 15 microm into the peripheral choroid; capillaries were included between the elastin layer and the RPE. Nasally, from the anterior end to 2 mm posterior of the ora serrata, the RPE cells contained more melanin than did those in the adjacent posterior region. Melanin granules in the RPE cells close to the ora either formed large clusters or appeared unusually small because of fragmentation. A unique, fine lam...
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1. Rhabdomeral microvilli of photoreceptor cells of invertebrates contain a labile central cytoskeleton. For stabilization of the rhabdomeral cytoskeleton of the crayfish Orconectes limosus the crosslinking reagent suberic acid bis... more
1. Rhabdomeral microvilli of photoreceptor cells of invertebrates contain a labile central cytoskeleton. For stabilization of the rhabdomeral cytoskeleton of the crayfish Orconectes limosus the crosslinking reagent suberic acid bis (N-hydroxysuccinimide ester) was used. 2. It was found that this crosslinking reagent can be successfully used to stabilize and isolate the microvillar cytoskeleton of crayfish photoreceptors. 3. After detergent treatment cytosolic proteins and the cell membranes were removed. 4. By the combined use of crosslinker and detergent the accessibility of antibodies or other markers to the microvillar cytoskeleton is possible. 5. This method may be useful, because at present little is known about the proteins associated with the central filament of invertebrate photoreceptors.