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Biomedical subjects

P Esser

Publications and source records attributed to P Esser.

At least 19 recordsLinked to original sources
PubMed2002

[Macular translocation with 360 degree retinotomy in the treatment if exudative macular degeneration. Functional and angiographic results].

BACKGROUND: During surgical extraction of choroidal neovascular membranes (CNV) in age-related macular degeneration (AMD), the defective foveal retinal pigment epithelium (RPE) is removed. Subsequent translocation of the foveal neural retina to adjacent healthy RPE should result in stabilization and possibly improvement of visual acuity. METHODS: A prospective case series was carried out using controlled surgery and examination protocols with examinations made at fixed intervals. The surgical procedures combine counterrotation of the globe, phacoemulsification and implantation of a posterior chamber lens, complete vitrectomy, induction of a total retinal detachment, 360 degrees anterior retinotomy, removal of the subfoveal neovascular complex, foveal translocation outside the RPE defect, reattachment of the retina using F6H8, peripheral laser retinopexy and temporary silicone oil tamponade. PATIENTS: Macular translocation surgery was performed on 100 patients between December 1997 and December 1999. All patients had experienced recent visual loss due to exudative AMD and of these, 26 patients had major macular subretinal hemorrhage, 39 patients had occult and 25 patients classic subfoveal choroidal neovascularization. The preoperative findings in the remaining patients included tears in the pigment epithelium (n = 4), polypoidal choroidal vasculopathy (n = 1), recurrent subfoveal CNV following laser therapy (n = 2) and deep retinal vascular anomalous complexes (n = 3). RESULTS: A total of 97 patients completed the 12-month examination. Visual acuity increased by 15 or more ETDRS chart letters in 24 patients, remained stable in 42 patients and deteriorated by 15 or more EDTRS chart letters in 34 patients 12 months postoperatively. The silicone oil tamponade was removed in 97 patients, in 10 patients, silicone oil had to be reinjected because of severe complications. A secondary procedure was necessary in 25 patients, primary PVR was observed in 9 eyes, secondary PVR developed in 10 eyes, a macular pucker in 5 eyes and a macular hole in 1 patient. Other postoperative complications included persistent hypotonia, macular edema, IOL dislocation, keratopathy and recurrent CNV (n = 3). CONCLUSIONS: Macular translocation is a technically demanding operation, which requires a considerable learning curve. Although the procedure has a high rate of surgical and postoperative complications, the functional and anatomical results appear to be promising for selected patients with subfoveal CNV secondary to AMD.

Aged↗
PubMed2001

TGF-beta in uveal melanoma.

Uveal melanoma is the most common primary ocular cancer among adults and patients with distant metastases seldom survive longer than a year. Melanomas of the eye have the advantage of growing in the special environment of an immune privileged site and it has long been shown, that the special immunosuppressive properties of the intraocular microenvironment are strongly mediated by cytokines, especially transforming growth factor-beta (TGF-beta). Here, we sought to investigate the presence of TGF-beta in surgically removed uveal melanoma specimens using immunohistochemical methods to verify possible autocrine mechanisms. Immunocytochemistry for pan-TGF-beta and TGF-beta(2) was performed on 13 melanoma specimens using an alkaline phosphatase labeling procedure. Melanocytic origin of the tumors was confirmed by HMB-45 staining. All tissue samples exhibited positive staining using either pan-TGF-beta or TGF-beta(2) antibody regardless of cell-type, size of the tumor, or tumor location. The intensity of staining did not vary significantly within a given tumor. All tumors stained positive against the HMB-45 antibody. Many cytokines have been found to act on melanoma tumors. The presence of the TGF-beta(2) isoform in all specimens points to progressive tumor-growth as has been shown for melanomas of the skin. Based on our immunohistochemical findings and the immunosuppressive properties of TGF-beta, we suppose that ocular melanomas should be able to create their own immunosuppressive environment even in the uvea, which might be a non-privileged site.

Aged↗
PubMed2001

Specific features of apoptosis in human lens epithelial cells induced by mitomycin C in vitro.

BACKGROUND: Posterior capsule opacification (PCO) is still one of the major complications following modern cataract surgery. Several attempts have been made to find an appropriate therapeutic concept to significantly lower the rate of PCO. Here, we wanted to focus on the antimetabolic strategy, reducing PCO by using mitomycin C, further characterizing the pathway of apoptosis in human lens epithelial cells (hLECs). METHODS: Human lens epithelial cells were obtained from anterior lens capsules during cataract surgery. The expression of Fas, TRAMP, TRAIL-R1-R4, Apo-3L and TRAIL mRNA was investigated by means of RT-PCR using specific primers. For investigations on bcl-2, bax, p53 and the active form of caspase 3, cell cultures of hLECs were pretreated with mitomycin C and processed for immunocytochemistry thereafter. RESULTS: We detected the expression of the receptors Fas, TRAMP, TRAIL-R2 and TRAIL-R3 in hLECs. We further obtained evidence of the upregulation of the intracellular apoptotic signalling cascade, represented by bcl-2 and bax, the transcription factor p53 and the active form of caspase 3, after pretreatment with mitomycin C. CONCLUSION: We demonstrated the presence of the apoptosis-receptor system in hLECs. Furthermore, we demonstrated the possibility of the induction of key proteins of the apoptotic signalling cascade in these cells by the antimetabolic drug mitomycin C. This could have important implications on the strategies regarding both the prevention and the treatment of PCO after cataract surgery.

Antimetabolites↗
PubMed2000

Age-related macular degeneration. The lipofusion component N-retinyl-N-retinylidene ethanolamine detaches proapoptotic proteins from mitochondria and induces apoptosis in mammalian retinal pigment epithelial cells.

10-20% of individuals over the age of 65 suffer from age-related macular degeneration (AMD), the leading cause of severe visual impairment in humans living in developed countries. The pathogenesis of this complex disease is poorly understood, and no efficient therapy or prevention exists to date. A precondition for AMD appears to be the accumulation of the age pigment lipofuscin in lysosomes of retinal pigment epithelial (RPE) cells. In AMD, these cells seem to die by apoptosis with subsequent death of photoreceptor cells, and light may accelerate the disease process. Intracellular factors leading to cell death are not known. Here we show that the lipophilic cation N-retinyl-N-retinylidene ethanolamine (A2E), a lipofuscin component, induces apoptosis in RPE and other cells at concentrations found in human retina. Apoptosis is accompanied by the appearance of the proapoptotic proteins cytochrome c and apoptosis-inducing factor in the cytoplasm and the nucleus. Biochemical examinations show that A2E specifically targets cytochrome oxidase (COX). With both isolated mitochondria and purified COX, A2E inhibits oxygen consumption synergistically with light. Inhibition is reversed by the addition of cytochrome c or cardiolipin, a negatively charged phospholipid that facilitates the binding of cytochrome c to membranes. Succinate dehydrogenase activity is not altered by A2E. We suggest that A2E can act as a proapoptotic molecule via a mitochondria-related mechanism, possibly through site-specific targeting of this cation to COX. Loss of RPE cell viability through inhibition of mitochondrial function might constitute a pivotal step toward the progressive degeneration of the central retina.

Aging↗
PubMed2000

Telemetry as a new concept in long term monitoring of SIDS-risk infant.

Sudden Infant Death Syndrome (SIDS) is the most frequent cause of infant death within the period of 2 to 12 months in western countries. It has been found that a suit similar to that worn by the astronauts during the execution of experiments on the Spacelab Mission D-2 is a very simple and useful means to carry the sensors required to monitor vital signs of babies at risk. A small baby-suit has been developed with the same technology used for the Spacelab Mission. The baby s suit is equipped with similar sensors to record thoracic and abdominal respiratory movements as its big -space travel brother-. This is a typical example of a successful technology transfer from medical aerospace activities into fields of daily clinical routine. In addition to the above described sensors, ECG-electrodes were integrated, as well as sensors to record vascular oxygen saturation and the corresponding pulse curve, and the baby s movements. All these vital signs are registered by a medical monitor, and permanently stored and automatically analysed online. In case of a life-threatening situation the system alerts simultaneously the personal at hospital and the parents at home. The requisite software algorithms have been developed by DLR in Cooperation with the pediatricians of the Pediatric Hospital in Köln-Porz, Cologne. When the system registers an alteration of the parameters above described -as a signal of a change in the baby s health condition- all vital signs are transfered in real-time to the supervising hospital via radio data transmission devices, mobile phone or a fixed network phone. The parents are also alerted by the device, and they can carry out the necessary reanimation procedures in case of an emergency. Parents will be trained in such actions when newborns must to be monitored. But nevertheless, they are guided and tele-assisted by an expert via telephone during the action. A clinical field trial, that will start in December 1999 at the Pediatric Hospital in Köln-Porz, Cologne, will evaluate the benefits of teleprotection by home monitoring of SIDS risk-babies.

Humans↗
PubMed2000

Transplantation of autologous iris pigment epithelium after removal of choroidal neovascular membranes.

BACKGROUND: Transplantation of autologous iris pigment epithelium (IPE) into the subretinal space has been suggested as one approach for the treatment of age-related macular degeneration, as well as for other conditions in which loss of retinal pigment epithelium (RPE) occurs. Surgical removal of choroidal neovascular membranes is associated with traumatic loss of the RPE cell layer, disruption of the integrity of the photoreceptor-RPE complex, and limited visual outcome. OBJECTIVE: To examine whether IPE cells can substitute for RPE cells to be transplanted to the subretinal space of patients with either RPE degenerative disease or traumatic loss of the RPE cell layer after subretinal surgery. METHODS: Autologous IPE cells were transplanted to the subretinal space in 20 consecutive patients undergoing removal of subretinal fibrovascular membranes using pars plana vitrectomy. Autologous IPE cells were harvested by iridectomy, isolated, and transplanted directly to the subretinal spaces. Transplants were evaluated for 6 to 11 months by funduscopy, fluorescein angiography, and scanning laser ophthalmoscopic (SLO) microperimetry. RESULTS: For the entire follow-up period, no evidence of any immunologic response was observed. Revisional surgery was necessary in 3 patients because of complications (rhegmatogenous retinal detachment [n = 1]; proliferative vitreoretinopathy [n = 1]; and macular pucker [n = 1]); 1 patient did not receive IPE cells. Five of 19 phakic eyes underwent cataract surgery; in 1 case this was combined with the vitrectomy. Five patients showed improved visual acuity of 3 to 4 lines, 13 patients had stable visual acuity (+/-2 lines), and 2 patients had reduced visual acuity of 6 lines. CONCLUSIONS: In this pilot study, the transplantation of autologous IPE cells was done as an addition to conventional surgical excision of choroidal neovascular membranes. Transplanted cells were well tolerated in the subretinal space and did not adversely affect the function of the photoreceptors, since improvement or stable visual acuity was observed in 18 patients after IPE transplantation. These results suggest that autologous IPE cells may be used as a substitute for autologous RPE cells to transplant to the subretinal space to treat age-related macular degeneration.

Adult↗
PubMed2000

Evidence for a constitutive, verapamil-sensitive, non-P-glycoprotein multidrug resistance phenotype in malignant glioma that is unaltered by radiochemotherapy in vivo.

Human malignant gliomas are commonly resistant to chemotherapy. Here, we examined the role of the multidrug resistance (mdr) mechanism in the chemo-resistance of these tumors, using a twofold approach: (i) by assessing a possible mdr phenotype before and after chronic drug exposure of glioma cells in vitro, and (ii) by assessing the modulation of expression of the mdr-associated P-glycoprotein (Pgp) using radiotherapy and serial cycles of chemotherapy in human glioblastoma patients in vivo. T98G, and to a lesser degree, LN-229 human malignant glioma cells exhibit a constitutive mdr phenotype as determined by the modulation of dye transport and by the augmentation of chemosensitivity by the mdr antagonist, verapamil. Thus, coexposure to verapamil enhances the cytotoxicity of vincristine, doxorubicin and VM26 in T98G cells and that of vincristine in LN-229 cells. Chronic exposure of the cells to low concentrations of vincristine and doxorubicin, but not VM26, topotecan or BCNU, moderately enhances the mdr-like phenotype, as assessed by drug expulsion assays. However, chronic exposure to increasing drug concentrations does not significantly alter the sensitivity to the respective drugs. These data are consistent with a constitutive, but not drug-inducible, mdr-like drug resistance in glioma cells in vitro. Immunocytochemical analysis of human malignant gliomas in vivo reveals that Pgp expression is more abundant in endothelial cells within the gliomas, than in the glioma cells proper. Importantly, Pgp expression is unaltered by radiochemotherapy, assessed by comparative immunocytochemistry of glioma specimens obtained serially before and after radiochemotherapy. We conclude that (i) glioma cells exhibit constitutive mdr-like drug resistance that is not significantly altered by chronic drug exposure in vitro; (ii) endothelial cells may play an important role in Pgp-mediated drug resistance of gliomas in vivo; (iii) radiotherapy and repeated chemotherapy cycles do not modulate Pgp expression in human malignant gliomas in vivo; (iv) there is preliminary evidence for a non-Pgp, verapamil-sensitive drug transport activity in glioma cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Multidrug resistance-associated proteins in glaucoma surgery.

BACKGROUND: Multidrug resistance (MDR) describes the phenomenon of cross-resistance between different cytostatic agents which are structurally and functionally dissimilar. Two recently discovered proteins, lung resistance protein (LRP) and the multidrug resistance-related protein (MRP) have been implicated in the development of MDR. Since resistance to chemotherapeutic agents is a common problem in filtration surgery, especially in cases of complicated glaucoma, we decided to investigate the presence of MRP and LRP in surgically removed Tenon specimens from glaucoma patients. METHODS: The presence of MRP and LRP in surgically removed Tenon tissue (n=15) was analyzed by immunohistochemistry. The expression by cultured Tenon fibroblasts was assessed by reverse-transcriptase polymerase chain reaction (RT-PCR) and fluorocytometry. RESULTS: LRP expression was detected in 8 of 10 Tenon specimens. Positive staining for MRP was obtained in 5 of 10 specimens. Negative controls with non-immune mouse IgG did not display any specific staining. RT-PCR and fluorocytometry revealed constitutive expression of MRP and LRP, at the RNA and protein level respectively, that was unaltered by pretreatment of the cells with mitomycin C or 5-fluorouracil. CONCLUSION: Our results demonstrate, that besides P-glycoprotein, other components of the MDR-system are present in conjunctival fibroblasts. Future developments in the use of chemotherapeutic agents in association with of filtration surgery need to take account of the presence of these counteracting mechanisms.

ATP-Binding Cassette Transporters↗
PubMed2000

Elevated vitreous nitric oxide levels in patients with proliferative diabetic retinopathy.

PURPOSE: The aim of this study was to determine nitric oxide levels in the vitreous of patients with proliferative diabetic retinopathy. METHODS: Using the spectrophotometric method based on Griess reaction, we measured levels of nitrite, the stable product of nitric oxide, in the vitreous of 21 eyes of 21 patients who underwent vitrectomy for the treatment of proliferative diabetic retinopathy with tractional retinal detachment, prospectively. Three samples were excluded from the study because of blood contamination. The control group was made up of vitreous samples from 15 eyes of 15 normal cadavers and five eyes of five patients who were undergoing vitrectomy for macular hole surgery. RESULTS: Nitrite levels were 0. 524 +/- 0.27 microM and 0.383 +/- 0.17 microM in the vitreous of patients with proliferative diabetic retinopathy of diabetes type I and type II, respectively. In 15 cadaver eyes and five vitreous samples from patients who underwent macular hole surgery, nitrite levels were below the detection limit (less than 0.08 microM). There was no significant difference between nitrite levels in patients with type I and type II diabetes (P =.56), whereas there was a significant difference between diabetes groups and controls (P <. 00001). CONCLUSION: Vitreous nitric oxide levels are elevated in patients with proliferative diabetic retinopathy with tractional retinal detachment. Nitric oxide may play a role in the pathogenesis of proliferative diabetic retinopathy.

Adult↗
PubMed2000

Effect of nitric oxide on proliferation of human retina pigment epithelial cells.

PURPOSE: To investigate the effects of exogenous and endogenous nitric oxide (NO) on the proliferation of human retina pigment epithelial (RPE) cells. METHODS: We stimulated cultured human RPE cells with 3-morphosydnonimine (SIN-1) to analyse the effect of exogenous NO. Incubation with a cytokine cocktail (interleukin 1-beta + interferon gamma + tumour necrosis factor alpha) plus lipopolysaccharide (LPS) induced cells to synthesise NO endogenously. The cultures were then incubated for 48 h, after which the cells were stained with crystal violet and absorbance at 550 nm was measured spectrophotometrically. RESULTS: SIN-1 inhibited human RPE cell proliferation, while haemoglobin, an NO inhibitor, almost completely blocked the inhibitory effect. On the other hand, treatment with the cytokine cocktail plus LPS did not inhibit RPE cell proliferation. CONCLUSION: These findings confirm that exogenous NO inhibits human RPE cell proliferation, while endogenous NO has no such blocking effect.

Cell Division↗
PubMed2000

Antiproliferative Wirkung von Genistein auf kultivierte retinale Pigmentepithelzellen vom Schwein.

UNLABELLED: The isoflavonoid genistein is known as a potent inhibitor of proliferation in endothelial cells and in some tumor cell lines in vitro and in vivo. Cell growth arrest is mediated by inhbitor of the tyrosine-kinase receptor, a target for many growth factors such as fibroblast growth factor, platelet-derived growth factor, epidermal growth-factor and vascular endothelial growth factor, which may play a role in the development of proliferative vitreoretinopathy (PVR). In this study we report on the antiproliferative effect of genistein on retinal pigment epithelial cells (RPE), which is the major cell type involved in PVR. METHODS: Cell culture experiments using porcine RPE treated with different concentrations (5 up to 100 microgram/ml) of genistein in minimum essential medium +10% fetal calf serum. Inhibition of proliferation was demonstrated by two different methods: (1) uptake of 5-bromo-2-deoxyuridin (BrdU) in S phase after different exposure times (2) expression of proliferating cell nuclear antigen 72 h after scratching confluent RPE. RESULTS: Exposure of RPE to genistein resulted in a concentration-dependent inhibition of cell proliferation at concentrations over 25 microgram/ml geinistein. BrdU incorporation was reduced to 65% after 24- and 48-hour treatment with 100 microgram/ml genistein in comparison with the untreated cells. Proliferation of RPE growing into the artificial wound was inhibited when cells were exposed for 72 h to more than 25 microgram/ml genistein. CONCLUSIONS: Genistein at concentrations over 25 microgram/ml inhibits RPE proliferation. Further studies will be required to determine the applicability of genistein or other phytoestrogens in order to prevent uncontrolled wound healing processes such as PVR.

Animals↗
PubMed1999

Upregulation of the RAS-GTPase activating protein (GAP)-binding protein (G3BP) in proliferating RPE cells.

Cultured human retinal pigment epithelial (RPE) cells of different passages (P0 and P3) were used as a model system to examine changes in gene expression in proliferating RPE cells by polymerase chain reaction (PCR)-based differential expressed mRNA analysis (DEmRNA-PCR). DEmRNA-PCR showed enhanced expression of a specific RNA in P3 compared with P0. Sequence alignment displayed its identity with the 3'-end of the coding sequence of the human RAS-GTPase activating protein (GAP)-binding protein (G3BP). Confirmation of the induced expression of G3BP was performed by gene-specific reverse transcription-polymerase chain reaction (RT-PCR) of freshly prepared human RPE cells and of cultured cells of P0, P3 and P8 and by immunohistochemistry of cultivated retinal pigment epithelial cells in an artificial lesion assay. The expression of G3BP mRNA increased with the number of passages. G3BP protein expression increased in cells repopulating the artificial lesion. DEmRNA-PCR in RPE cells with subsequent sequence analysis led to the characterization of dedifferentiation- and proliferation-dependent expression of a previously undetected gene product in cultured RPE cells with a possible role in modifying signal transduction responses that may have implications on the treatment of proliferative vitreoretinopathy.

Aged↗
PubMed1999

SPECT study of visual fixation in schizophrenia and comparison subjects.

BACKGROUND: The consistent association of impaired eye movements and schizophrenia suggests a relationship between the neurobiology of the illness and visual pursuit systems. Visual fixation (VF), an eye "movement" task at zero velocity, is the simplest such abnormality in schizophrenia patients and their relatives. METHODS: We used a VF task for a functional imaging study. Six neuroleptic-free schizophrenia patients and eight gender and mean age matched comparison subjects had SPECT scans with 20 mCi of Tc99-HMPAO, during VF on a simple blue line intersection. MEDX data saved in ANALYZE format for SPM 95 was used to generate paired t-test statistical data for display in Talairach space, with rCBF changes given as Z-scores. RESULTS: Patients, compared to controls, had increased rCBF in both the parahippocampal gyrus (bilaterally) and in the right fusiform gyrus. They had decreased rCBF in the left frontal cortex, including medial and superior frontal gyri and anterior cingulate. Overall, compared to controls, patients had medial temporal lobe hyperperfusion along with left prefrontal hypoperfusion. CONCLUSIONS: These findings are consistent with the hypothesized imbalance between the medial temporal and frontal lobes that is postulated for schizophrenia. It was of interest that the relative rCBF differences between schizophrenia patients and controls in this small sample were observable with this cognitively non-demanding visual fixation task.

Adult↗
PubMed1999

Ultrastructural localization of lipid peroxides as benzidine-reactive substances in the albino mouse eye.

BACKGROUND: Lipid peroxidation is considered to be a prominent feature of retinal degeneration and has also been proposed to be involved in the pathogenesis of age-related macular degeneration. Melanin protects against lipid peroxidation and takes part in the detoxification of lipid peroxides (LP). LP can be ultrastructurally detected as benzidine-reactive substances (BRS) using tetramethylbenzidine (TMB). Albino mice lack melanin. In the present study, LP were localized as BRS in the eyes of albino and pigmented mice. METHODS: Eye cups of an albino mouse lineage and of wild-type mice were fixed with 2% glutaraldehyde, incubated with 0.5 mg/ml TMB and embedded for electron microscopy. RESULTS: BRS were detected in the eyes of albino mice, but no reaction product was seen in pigmented eyes. BRS located in the retinal pigment epithelium (RPE) and in the choroid of the albino mouse; no BRS were found in intact rod outer segments (ROS). CONCLUSION: The lack of melanin in albino mice is associated with a higher level of lipid peroxidation in RPE and choroid. Melanin seems to protect against LP in RPE and choroid. A lack of melanin is not associated with lipid peroxidation in intact ROS. The present investigation demonstrates the significance of melanin in protection against LP in RPE and choroid.

Animals↗
PubMed1999

Detection of mRNA for proteins involved in retinol metabolism in iris pigment epithelium.

BACKGROUND: To investigate in iris pigment epithelium (IPE) the expression of mRNA for proteins involved in retinol metabolism we used a semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) technique. METHODS: RNA was prepared from freshly isolated bovine IPE and retinal pigment epithelium (RPE) cells and reverse transcribed. The expression of mRNA for cellular retinaldehyde binding protein (CRALBP), p63 (RPE63), the presumed retinal pigment epithelial membrane receptor for retinoids, and 11-cis-dehydrogenase (11cisRDH) was determined by RT-PCR using specific primers. Semi-quantitative expression data were obtained by using a series of fivefold dilution of each cDNA with a fixed number of PCR cycles. RESULTS: Bovine IPE and RPE cells express mRNA for CRALBP, 11cisRDH, and RPE63. The mRNA expression for CRALBP and 11cisRDH is high and equal in both cell types. However, RPE63 mRNA expression in IPE cells is relatively low compared with the expression in RPE cells. CONCLUSIONS: The presence of mRNA for CRALBP, RPE63, and 11cisRDH suggests that IPE cells may be able to metabolize retinol.

Aldehyde Oxidoreductases↗
PubMed1999

Acute corneal necrosis after excimer laser keratectomy for hyperopia.

OBJECTIVE: To describe a new, rare clinical complication after routine excimer laser photorefractive keratectomy to correct hyperopia. DESIGN: Case report with clinicopathologic correlation. MAIN OUTCOME MEASURES: Four weeks after treatment with excimer laser, a perforating keratoplasty was performed for persistent corneal opacities. The corneal button was examined using light and electron microscopy. Special immunohistochemical stains were used to detect apoptosis. RESULTS: The patient developed corneal opacities, endothelial precipitates, and a fibrinous exudate in the anterior chamber after the laser treatment. The changes did not respond to therapy directed against bacteria, fungi, and Acanthamoeba. All examinations and special stains were negative for micro-organisms. By light microscopy, an anterior zone of corneal necrosis was present with a moderate amount of acute inflammatory cells. At the interface between necrotic and viable corneal stroma, keratocytes with typical features of apoptosis were detected by immunohistochemistry and electron microscopy. CONCLUSION: This is the first full histopathologic report of a case of acute corneal necrosis with signs of apoptosis after excimer laser therapy of the cornea. Surgeons should be aware of this rare but potentially severe complication.

Acute Disease↗
PubMed1998

The mRNA expression of cytokines and their receptors in cultured iris pigment epithelial cells: a comparison with retinal pigment epithelial cells.

It has been suggested that human iris pigment epithelial (IPE) cells isolated from iridectomized tissue could be used as autologous cells for transplantation into the subretinal space in diseases with dysfunctional retinal pigment epithelium (RPE). RPE cells synthesize a number of cytokines and their receptors which are important for its proper function. Nearly nothing is known about the capacity of IPE to synthesize cytokines or responding to them. To compare the mRNA expression of 36 cytokines or their receptors in cultured adult IPE cells and RPE cells we used semi-quantitative reverse transcription polymerase chain reactions (RT-PCR). Included in our assay were cytokines with known expression in RPE to get a broad basis for comparing IPE cells: basic fibroblast growth factor (bFGF or FGF-2), and one of its receptor (FGFR-1), epidermal growth factor (EGF), and its receptor EGF-R, transforming growth factor beta(TGFbeta), and its type III receptor TGFbeta-R3, the platelet-derived growth factors and receptors (PDGF A, PDGF B, PDGF-Ralpha, PDGF-Rbeta), tumor necrosis factor alpha(TNFalpha), and two receptors TNF-R1 and TNF-R2, insulin (INS) with receptor INS-R, insulin-like growth factors (IGF1, IGF2), and receptors (IGF1-R, IGF2-R), vascular endothelial growth factor (VEGF), and two receptors (VEGF-R1 or FLT-1 and VEGF-R2 or FLK-1), the receptor for VEGF-C: VEGF-R3 or FLK-4, interleukin 6 (IL6), and its receptor (IL6-R), nerve growth factor (NGF), interleukin 1alpha(IL1alpha), and a receptor (IL1-R). In addition, cytokines or their receptors not known to be expressed in RPE were included to widen our picture of cytokine gene expression in the eye: stem cell factor (SCF), its receptor (SCF-R), low-affinity nerve growth factor receptor p75 (p75(NGF-R), ciliary neutrothropic factor (CNTF), and its receptor (CNTF-R), glycoprotein 130 interleukin 6 transducer (gp130 (IL6-SD), leukemia inhibitory factor (LIF), and its receptor (LIF-R). Semi-quantitative expression data were obtained using series of fivefold dilutions of each cDNA and a fixed number of PCR cycles. The expression of RPE 65, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta2-microglobulin (B2MG) was used as a control for cellular origin, RNA quality and PCR conditions. With the exception of insulin and tumor necrosis factor alphaall other cytokines analysed and their receptors were expressed in both IPE and RPE cells, even though the levels varied. No qualitative or quantitative difference were observed in the mRNA expression level of 34 (94%) of the cytokines or receptors between IPE and RPE. In contrast, the mRNA expression level of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 [VEGF-RS (FLK-1)] was lower in IPE than in RPE cells. As an increased expression of VEGF in the RPE in maculae with age-related macular disease could be involved in its pathogenesis, a decreased expression of angiogenic growth factors in IPE cells could possibly be beneficial for the therapy of age-related maculopathy if indeed other tasks of non-functional RPE cells could be performed by IPE cells. The similarity of the mRNA expression pattern in 94% of the cytokines analyzed supports the assumption that IPE cells potentially can perform functions of RPE cells in the appropriate environment.

Adult↗