Biomedical subjects

P Esser

Publications and source records attributed to P Esser.

At least 37 records · Page 2Linked to original sources

PubMed1998

The topoisomerase I inhibitors, camptothecin and beta-lapachone, induce apoptosis of human retinal pigment epithelial cells.

The aim of the study was to determine whether the topoisomerase I inhibitors, camptothecin and beta-lapachone, are suitable agents for the adjuvant pharmacotherapy of proliferative vitreoretinopathy (PVR). The effects of the drugs on cultured human retinal pigment epithelial (RPE) cells were examined using growth assays, cytotoxicity assays, single cell agarose gel electrophoresis, in situ DNA end labeling and immunoblot analysis for apoptosis-regulatory proteins. Both agents killed RPE cells in a concentration-and time-dependent manner. Cell death was apoptotic as assessed by single cell agarose gel electrophoresis and in situ DNA end labeling. Camptothecin, but not beta-lapachone, induced accumulation of p53 and the major growth arrest-associated p53 response protein, p21. Both drugs enhanced expression of the proapoptotic BAX protein. Camptothecin, but not beta-lapachone, synergistically enhanced RPE cell apoptosis induced by the cytotoxic cytokine, CD95 ligand (CD95L). This effect was linked to camptothecin-induced inhibition of RNA synthesis. Atypical topoisomerase I inhibitors may be promising agents for the adjuvant pharmacotherapy of PVR. Experimental studies to assess possible ocular toxicity upon local administration and to confirm its therapeutic efficacy in an animal model of PVR are required.

Apoptosis↗

PubMed1998

The nonradioisotopic representation of differentially expressed mRNA by a combination of RNA fingerprinting and differential display.

In many applications, an understanding of differentially expressed genes in different tissues or owing to an applied stimulus is important. However, the wide use of two rather similar polymerase chain reaction (PCR)-based techniques for the identification of differentially expressed mRNAs (RNA fingerprinting by arbitrarily primed PCR [RAP-PCR] and differential display [DDRT-PCR]) has shown that reproducibility is still a problem. By combining features of both RAP-PCR and DDRT-PCR, a technique has recently been developed that avoids some of the disadvantages, but the use of radioisotopes for band detection still limits its application. We have improved this technique for analyzing differentially expressed mRNA by resolving the amplified products on nondenaturing polyacrylamide gels and subsequently staining the gels with silver nitrate. Our modification allows the identification of differentially expressed bands with a very high accuracy. Therefore these bands can be very easily reamplified and sequenced directly. Subsequently the differential expression can be verified by semiquantitative RT-PCR with specific primers derived from sequence data. These improvements, together with nonradioactive sequencing techniques, make it possible to do DD analysis completely without a health hazardous owing to radioactivity. The nonradioisotopic differentially expressed mRNA-PCR (DEmRNA-PCR) is a reliable and useful modification of available differential expression methods.

Cells, Cultured↗

PubMed1998

External beam radiation in patients suffering from exudative age-related macular degeneration. A matched-pairs study and 1-year clinical follow-up.

BACKGROUND: The aim of this prospective study was to ascertain whether external beam irradiation is effective in patients with subretinal neovascularization (SRN) due to age-related macular degeneration (AMD). METHODS: All patients had subfoveal SRN due to AMD as verified by fluoresceinangiography. Two hundred and eighty-seven patient-eyes were treated by external beam irradiation (total dose of 16 Gy in 2-Gy fractions, 5 times a week) from January 1996. The analysis was restricted to those 73 patients with a minimum follow-up of 11 months. Eighteen patients with subfoveal SRN who refused treatment served as control group (CG). 18 patients of the treatment group (TG) were matched for visual acuity, refraction and extent of SRN. The statistical analysis was performed with the unpaired t-test. RESULTS: The mean age of the CG was 73.9 years (range 66.9-81.3 years) and of the TG 75.6 years (range: 65.7-80.6 years). The median follow-up was 13.5 months (range 11.9-18.4 months) in the CG and 12.9 months (range 11-13.9 months) in the TG. The initial visual acuity (VA) was 20/80 in both groups. After 7 months the follow-up revealed median VA of 20/400 in the CG and 20/160 in the TG (P=0.0335). The final median VA was 20/400 in both groups, with a range from 20/40 to 20/1000 in the CG and from 20/63 to 20/500 in the TG (P=0.2433). The SRN doubled in size during this time in both groups. CONCLUSION: These results suggest that external beam irradiation applied in 2-Gy fractions 5 times a week slows down the visual loss in exudative AMD for a short time. Nevertheless, the patients' reading vision could not be saved in the long term.

Aged↗

PubMed1998

Intravitreal daunomycin induces multidrug resistance in proliferative vitreoretinopathy.

PURPOSE: Adjuvant intravitreal daunomycin is frequently used for the management of proliferative vitreoretinopathy (PVR). In this study the authors examined whether daunomycin could induce multidrug resistance (MDR), mediated by the mdr-1 gene product P-glycoprotein, in the cells responsible for reproliferation in vivo and in human retinal pigment epithelial (RPE) cells in vitro. METHODS: Expression of P-glycoprotein was examined by immunohistochemistry in surgically removed epiretinal membranes. The cellular source of P-glycoprotein was examined by colabeling for cytokeratin, glial fibrillary acidic protein, and the macrophage marker EBM-11. P-glycoprotein expression by cultured RPE cells was assessed by reverse transcription-polymerase chain reaction and immunoblot analysis. Daunomycin toxicity was quantified by crystal violet assay. RESULTS: P-glycoprotein expression was detected in 10 of 10 patients pre-exposed to intravitreal daunomycin. In contrast, epiretinal membranes from only 2 of 13 patients never exposed to daunomycin showed faint P-glycoprotein expression. P-glycoprotein expression was strong within 8 months after daunomycin treatment and faded thereafter. Colocalization studies demonstrated predominant expression of P-glycoprotein by RPE cells. Pre-exposure of cultured human RPE cells to subtoxic concentrations of daunomycin induced resistance to daunomycin that was sensitive to the MDR inhibitor, verapamil. Induction of the MDR phenotype in RPE cells by daunomycin was associated with a minor increase in the mdr-1 mRNA level but a prominent increase in P-glycoprotein expression, thus suggesting a primarily translational mechanism of MDR development in human RPE cells. CONCLUSIONS: Intravitreal daunomycin induced P-glycoprotein expression in PVR. Reproliferation in daunomycin-pretreated patients probably necessitates cotreatment with daunomycin and inhibitors of multidrug resistance such as verapamil or administration of antiproliferative drugs such as 5-fluorouracil, which act in a MDR-independent fashion.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Capillaries are present in Bruch's membrane at the ora serrata in the human eye.

PURPOSE: 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. METHODS: 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. RESULTS: 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 lamellar, membranous material with a fingerprint-like structure was found between the basal folds of the RPE. This material is also found within the extracellular matrix of the choroid and in association with red blood cells. CONCLUSIONS: The morphology of Bruch's membrane is varied near the ora serrata because capillaries and wandering cells are present in its outer collagenous layer. Unique, fine lamellar, fingerprint-like structures are extruded from the RPE and are removed from the eye together with red blood cells. Capillaries within the inner collagenous region of Bruch's membrane at the ora serrata may not necessarily represent a pathologic response but may be a normal characteristic of thick regions of Bruch's membrane.

Bruch Membrane↗

PubMed1997

Topoisomerase-I inhibitors for human malignant glioma: differential modulation of p53, p21, bax and bcl-2 expression and of CD95-mediated apoptosis by camptothecin and beta-lapachone.

Beta-lapachone and camptothecin are structurally unrelated agents thought to inhibit topoisomerase-I activity through distinct mechanisms. We find that beta-lapachone is much more potent than camptothecin in inducing acute cytotoxic effects on human malignant glioma cells. Acute cytotoxicity induced by both drugs is apoptotic by electron microscopy, but not blocked by inhibitors of RNA or protein synthesis and not associated with changes in the expression of bcl-2, bax, p53, p21 or GADD45 proteins. In contrast, prolonged exposure of glioma cells to both drugs for 72 hr results in growth inhibition and apoptosis, with EC50 values around 1 microM. None of 7 glioma cell lines tested were resistant to either drug. LN-229 cells which have partial p53-wild-type activity show enhanced expression of p53, p21 and bax protein, whereas bcl-2 levels decrease, after exposure to camptothecin. In contrast, beta-lapachone increases bax protein expression in the absence of p53 activation. T98G cells are mutant for p53. In these cells, p53 levels do not change and p21 is not induced. bax accumulation in T98G cells is induced by both drugs, with bcl-2 levels unaltered. Surprisingly, ectopic expression of murine bcl-2 fails to abrogate the toxicity of either drug. Camptothecin, but not beta-lapachone, sensitizes human malignant glioma cells to apoptosis induced by the cytotoxic cytokines, tumor necrosis factor-alpha and CD95 ligand. Thus, both drugs have potent anti-glioma activity that may be mediated by enhanced bax expression but is not inhibited by ectopic bcl-2 expression. Camptothecin-like agents are particularly promising for immunochemotherapy of malignant glioma using cytotoxic drugs and CD95 ligand.

Apoptosis↗

PubMed1997

Apoptosis in proliferative vitreoretinal disorders: possible involvement of TGF-beta-induced RPE cell apoptosis.

The targeted induction of apoptosis is a novel therapeutic approach to control the unlimited growth of proliferating cells. Since massive proliferation of cells at the vitreoretinal interface is a key feature of proliferative vitreoretinal disorders, we sought to identify apoptosis in epiretinal membranes from patients with proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR) and macular pucker. Further, we evaluated the possible induction of apoptosis of retinal pigment epithelial (RPE) cells by transforming growth factor-beta(TGF-beta). Apoptotic cells were identified by in situ DNA end labeling and acridine orange staining on paraffin-embedded tissue sections from epiretinal membranes of patients with all vitreoretinal disorders examined. Labeled nuclei or condensed chromatin were scattered throughout the membranes or occurred in clusters. Most apoptotic cells were RPE-derived, as assessed by cytokeratin immunochemistry. No apoptotic glial cells were detected. In PVR, proliferative activity, as confirmed by Ki-67 immunochemistry, was associated with short history and rapid disease progression. Apoptotic nuclei were observed more frequently in long-standing PVR or slow progression towards traction retinal detachment. TGF-beta was detected in all control vitreous samples by bioassay at concentrations below 20 ng ml-1. TGF-beta levels increased up to 20-fold in pathological vitreous. Marked heterogeneity was observed in all patient groups. The degree of TGF-beta activation was significantly higher in PVR than in PDR. Proapoptotic effects of TGF-beta were demonstrated in cultured human RPE cells by electron microscopy, in situ DNA end labeling, comet assay and a photometric enzyme immunoassay for histone-associated DNA fragments. Apoptosis appears to be a key regulatory mechanism of growth control of specific cell populations in proliferative vitreoretinal disorders. Administration of proapoptotic growth factors such as TGF-beta may provide a novel approach to inhibit cellular proliferation at the vitreoretinal interface.

Apoptosis↗

PubMed1997

Cytochemical localization of guanylate cyclase in photoreceptor cells of the mouse.

BACKGROUND: Light-stimulated excitation causes a decrease of the cGMP concentration in vertebrate photoreceptor cells. The cGMP content is restored by the catalytic action of a guanylate cyclase (EC 4.6.1.2). METHODS: The spatial distribution of guanylate cyclase was determined cytochemically in rod visual cells of the mouse. RESULTS: In retinal tissue of the mouse guanylate cyclase was found throughout the photoreceptor cells, in the outer and the inner segments, and was especially prominent in the cilia and in elongations of cilia extending into the outer segments. A reaction product of adenylate cyclase (EC 4.6.1.1) could not be demonstrated in vertebrate rod outer segments. CONCLUSION: The relatively high amount of guanylate cyclase in the inner segments and the cilia may contribute-at least in part-to the actual concentration and the time course of concentration changes of the cGMP concentration in rod outer segments.

Adenylyl Imidodiphosphate↗

PubMed1997

Retinal pigment epithelial cells: autocrine and paracrine stimulation of extracellular matrix contraction.

BACKGROUND: This study was carried out to examine the biological activity of contraction promoters produced by dedifferentiating retinal pigment epithelial cells (RPE) and to evaluate the importance of autocrine and paracrine effects within a semi-closed environment like the vitreal cavity. METHODS: RPE at different stages of dedifferentiation in culture were examined for their ability (a) to generate tractional forces in vitro, with and without serum stimulation, and (b) to produce and release contraction-stimulating proteins. Autocrine versus paracrine effects of cell-secreted promoters were tested by using RPE or human dermal fibroblasts (HDF) as target cells. The contraction-stimulating activity of the cell-secreted promoters was partially characterized and compared to the activity of defined promoters. RESULTS: Our study confirmed that RPE can synthesize and secrete cell-contraction-promoting factor(s) active in stimulating the development of tractional forces by RPE as well as HDF. The quantity of biological activity secreted per cell decreases with progressive dedifferentiation, yet the responsiveness of the cell to contraction promoters increases. The contraction promoter(s) synthesized by RPE is partially distinct from the promoters in serum, TGF-beta 1 and beta 2, IGF-1, ET-1 and PDGF. The contraction-promoting effects of the RPE product(s) can be completely blocked by staurosporine. CONCLUSION: De-differentiation of RPE is characterized by increasing capacity to generate tractional forces and decreasing synthetic capacity. RPE within a semi-closed system like the vitreal cavity can, theoretically, act both as promoting and active component of traction-related events (tractional retinal detachment).

Animals↗

PubMed1997

[Vitrectomy in treatment of eyes with complicated uveitis].

BACKGROUND: Vitrectomy serves as an important treatment modality in uveitis, removing inflamed vitreous body and eliminating secondary complications. The aim of our retrospective study was to evaluate the value of vitrectomy in the treatment of complications in uveitis. PATIENTS AND METHOD: We included 50 eyes of 50 patients suffering from chronic uveitis, which underwent vitrectomy surgery during the period of 1990 to 1993. The study only included patients who had vitrectomy for uveitis for the first time. Indications leading to surgery were density of optic media, retinal detachment, cyclitic or preretinal membranes. The mean follow-up was 455 (range 48-1420) days. RESULTS: Vitrectomy was performed at a mean delay of 452 days after initial presentation. The mean visual acuity at the time of surgery was 0.05. The best visual acuity postoperatively was measured at a mean time of 118 days after vitrectomy. Overall, at the last control, eyes with preoperative retinal detachment presented a much worse final functional result (visual acuity of 0.02) than eyes without detachment (visual acuity of 0.5). Ten eyes resulted in hypotonia after surgery (7 eyes with persisting hypotonia). Most frequent complications in the postoperative course were macular pucker (11 eyes), secondary glaucoma (10 eyes), macular edema (6 eyes) and retinal detachment (6 eyes). Fifty percent of all complications occurred within the first 3 months following surgery. CONCLUSION: Vitrectomy leads to a permanent increase in visual acuity through the treatment of complications, on the condition that a stable retinal situation was present preoperatively.

Adult↗

PubMed1997

The artificial iris diaphragm for vitreoretinal silicone oil surgery.

BACKGROUND: Silicone keratopathy frequently develops as a complication of silicone oil tamponade in the management of severe trauma in eyes with partial or complete aniridia. We therefore designed an "open" artificial iris diaphragm to prevent silicone oil-endothelial contact. In hypotony, where insufficient circulation of aqueous allows silicone in the anterior chamber despite an open diaphragm, a new solution became necessary. The "closed" artificial diaphragm was developed. METHODS: In this retrospective study, two consecutive series of artificial iris diaphragms were compared. Forty-four patients received either an open type (20 eyes) or a closed type (24 eyes) and were observed for 409 +/- 421 days (range, 32-1912). All eyes were aphakic, normotonous, and had a traumatic, compromised iris diaphragm or were aphakic and hypotonic as a result of injury, proliferative vitreoretinopathy, proliferative diabetic retinopathy, or uveitis, with an intact natural iris diaphragm. RESULTS: Silicone oil was retained behind the open diaphragm throughout the observation period in 40% of the eyes. Major long-term complications were hypotony and fibrous overgrowth. Silicone was retained behind the closed diaphragm in 50% of the eyes. CONCLUSION: Because proliferative vitreoretinopathy is active for months and multiple surgical interventions become necessary to avoid phthisis in eyes with highly pathologic changes, longstanding or permanent silicone tamponade is used. The artificial diaphragm prevents silicone-corneal contact in approximately 50% of aphakic eyes for at least 1 year.

Adolescent↗

PubMed1997

Analysis of UVB-modulated gene expression in human keratinocytes by mRNA differential display polymerase chain reaction.

Ultraviolet (UV) light is the most important environmental insult to skin. Even a single exposure to UVB radiation can result in inflammation and may also lead to DNA damage and apoptosis in the acute response of the cutaneous tissue. To elucidate the complex alterations of gene expression in human keratinocytes underlying these UV responses we took advantage of differential display polymerase chain reaction (DD-PCR) technology's ability to detect qualitative and quantitative changes in gene expression in more than two cell populations simultaneously. We demonstrate that low-dose UVB (100 Jm-2) leads to both induction and downregulation of different genes during the 24 h after irradiation in a time-dependent manner. In addition to the identification of known genes as possible effectors or targets in the UV response of human keratinocytes, we here identify a new sequence that is negatively regulated by UVB irradiation and was termed HUR 7 (HaCaT UV repressed). In general our results showed that DD-PCR is a useful tool in the analysis of quantitative changes of mRNA levels in human keratinocytes after UV irradiation. The identification of new UVB-repressed genes offers the opportunity to identify unrecognized molecular mechanisms in the UV response of human cells.

Blotting, Northern↗

PubMed1997

Plasminogen in proliferative vitreoretinal disorders.

OBJECTIVE: Intravitreal fibrin formation is a frequent observation after vitrectomy performed for a variety of vitreoretinal disorders including proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR), and endophthalmitis. Plasminogen activators (PA) have been used for the management of this postoperative complication. This approach requires the presence of plasminogen, the substrate for PA mediated fibrinolysis, in the vitreal cavity. METHODS: Quantification of plasminogen in the vitreous of 60 patients with PVR, PDR, and macular pucker was performed by streptokinase mediated activation using a chromogenic substrate. The presence of immunoreactive plasminogen was confirmed by immunoblot analysis of vitreal proteins and immunocytochemistry of surgically removed epiretinal membranes. RESULTS: Plasminogen levels were dramatically increased in the vitreous of PVR and PDR patients compared with macular pucker patients and normal controls. Staining for plasminogen in epiretinal membranes was confined to the extracellular matrix. Predominant staining of perivascular areas in PDR specimens indicated that breakdown of the blood-retinal barrier is an important source of intravitreal plasminogen in that condition. CONCLUSION: Plasminogen may play a role in traction membrane formation in PVR and PDR. Our biochemical analysis of presurgical vitreous indicates that there may be abundant substrate for PA mediated fibrinolysis in the vitreous cavity after vitrectomy.

Eye Diseases↗

PubMed1997

Expression and upregulation of microtubule-associated protein 1B in cultured retinal pigment epithelial cells.

PURPOSE: During routine cell culture and under pathologic conditions, human retinal pigment epithelial (RPE) cells lose epithelial characteristics and change their morphology. In this study, changes in gene expression in RPE cells of different generations were evaluated by polymerase-chain-reaction-based differential display mRNA analysis (DD-RT-PCR). METHODS: Total RNA was prepared from freshly isolated and cultured human RPE cells of passages P0 and P3 and was subjected to DD-RT-PCR. One band with enhanced expression was excised, reamplified, and partially sequenced, using a modified dideoxy chain termination approach. Expression of the corresponding protein was ascertained by immunocytochemical analysis. RESULTS: Differential display RT-PCR showed enhanced expression of a specific RNA in P3 cells compared with that in P0 cells. Sequence alignment revealed 98% identity with the 3' end of the coding sequence of human microtubule-associated protein 1B (MAP1B). Confirmation of induced expression of MAP1B mRNA was obtained by PCR with specific primers and by immunocytochemical analysis in cultured RPE cells and in surgically removed epiretinal membranes from patients with proliferative vitreoretinopathy. No expression of MAP1B mRNA or protein was detected in freshly isolated RPE cells. CONCLUSIONS: Differential display RT-PCR in RPE cells with subsequent sequence analysis allows characterization of the maturation- and differentiation-dependent expression of previously undetected genes and gene products in cultured RPE cells.

Animals↗

PubMed1996

The triple flash electroretinogram and its significance in macular diseases. B-wave recovery as a diagnostic tool.

PURPOSE: The purpose of this study was to evaluate recovery data for the b-wave of the electroretinogram (ERG) elicited using multiple flash stimulation with increasing stimulus intervals in normal controls and in patients with macular diseases. The results will describe effects of age and macular disease and define indexes characterizing the recovery process. METHODS: Scotopic Ganzfeld flash ERGs were elicited using interstimulus intervals of 140, 280, and 560 ms. Relative b-waves were calculated as the ratio b140 ms/b560 ms and b280 ms/b560 ms, respectively. Responses obtained in 134 eyes of 134 normal controls served as reference data. Fifty-four patients with different macular diseases were also examined and their data compared to the reference data. RESULTS: Relative b-wave amplitudes correlated with interstimulus interval and with flash luminance, but not with age. All patients had a normal ERG when recorded following the standard of clinical electroretinography. A sigmoidal model was suggested, providing three indexes characterizing the b-wave recovery process. Relative b-waves and recovery indexes varied in age-related macular degeneration, central serous retinopathy, vitelliform macular degeneration, Stargardt's disease, and pattern dystrophy. CONCLUSION: The triple flash ERG reflects energy-yielding and -utilizing mechanisms. It proved to be more sensitive in detecting functional lesions in macular diseases than the standardized explorating procedure. The b-wave recovery model allows differentiation between two independent mechanisms contributing to the b-wave recovery process. One or more of the three characterizing indexes are affected in different macular diseases.

Adolescent↗

PubMed1996

The cumulative normalised rim/disc area ratio curve.

BACKGROUND: The assessment of the cup of the optic disc depends, among other criteria, on the disc area. A small cup in a small optic disc can indicate an advanced glaucomatous lesion, while on the other hand a large cup in a large optic disc can be normal. Therefore, a cumulative normalised rim/disc area ratio curve could help to distinguish between glaucomatous and normal optic cups. The aim of our study was to calculate normalised rim/disc area ratio curve. METHODS: Heidelberg Retina Tomograph examinations of the optic nerve head of 100 randomly selected eyes of 100 normal subjects were evaluated. We calculated the disc area-adjusted normalised rim/disc area ratio in sectors of 10 degrees. The 95th, 90th and 50th percentiles of each of the 36 sectors were displayed in descending order. RESULTS: In relation to the normal percentile curves, it is possible to display an individual normalised rim/disc area ratio curve. We obtained such curves for a normal optic disc, optic nerve heads with moderate and advanced lesions and a small optic disc with glaucomatous damage. CONCLUSION: We present a new display mode for the results of Heidelberg Retina Tomograph optic nerve head examination, which may be helpful for easy and reliable assessment of the local, diffuse and combined components of glaucomatous optic nerve head damage depending on optic disc size.

Adult↗

PubMed1996

[Effects of fluorescein and indocyanine green angiography on subsequent dark adaptation and the electroretinogram].

BACKGROUND: In clinical practice the electroretinogram (ERG) usually should not be recorded immediately after conventional fluorescein angiography (FLA), because of the bleaching effects of strong light exposure on the course of dark adaptation and on the ERG. Currently it is not known, if indocyaningreen (ICG) angiography using the Heidelberg Retina Angiograph (HRA) has similar effects on the outer retina and if therefore the ERG should also not be recorded after ICG angiography. METHODS: Eight patients with different retinal diseases were examined. After 5 minutes of light adaptation to 160 cd/m2, Ganzfeld ERGs were repeatedly recorded using DTL electrodes during a 30 minutes dark period with a flash luminance of 0.1 cds/.m2. After this dark adaptation period a standardized ERG was recorded according to the ISCEV recommendations. This procedure was followed either by ICG angiography using the HRA or by conventional fluorescein angiography using the Canon CF 60 fundus camera. Within an interval of 5 minutes the above mentioned ERG procedure was repeated. RESULTS: ICG angiography using the HRA did neither affect the course of dark adaptation as measured by increasing b-wave amplitudes during the 30 minutes dark adaptation period, nor the values for each response of the Ganzfeld standard ERG. FLA did neither affect b-wave responses to dim stimuli, nor to stronger stimuli in the scotopic range. However, the course of dark adaptation was significantly prolonged after FLA. The maximum b-wave was not affected. CONCLUSIONS: ICG angiography using the HRA could be performed prior to the recording of the ERG, without any effect on the ERG. In contrast conventional FLA must be performed after ERG recordings, in order not to alter the electrophysiological responses.

Adult↗

PubMed1996

Apoptotic cell death in proliferative vitreoretinopathy.

Apoptosis is a selective event of physiological cell deletion that plays a crucial role in the development of numerous tissues, including the retina. In this paper we report the occurrence of apoptosis in epiretinal membranes derived from patients with proliferative vitreoretinopathy (PVR). Detection of apoptosis was performed by an in situ DNA-end labeling technique using terminal transferase-mediated deoxyuridine triphosphate (dUTP) incorporation. Apoptotic nuclei exhibiting chromatin condensation and fragmentation were also identified by acridine orange fluorescence. Apoptosis was detected in varying numbers of cells. The typical appearance of apoptotic nuclei, including nuclear chromatin condensation, was detected scattered inhomogeneously throughout the epiretinal membranes, in clusters, or even in single cells. Induction of apoptosis in human retinal pigment epithelial (RPE) cells by daunomycin could be demonstrated by in situ DNA end labeling and by quantitative determination of cytoplasmatic histone-associated DNA fragments using a photometric enzyme immunoassay. Since apoptosis has been shown to be an important factor in the growth control of various untransformed and neoplastic cell populations, the pharmacological induction of apoptosis in epiretinal membranes could result in a new approach toward inhibiting cellular proliferation in PVR.

Adult↗