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Gabriele Thumann

Publications and source records attributed to Gabriele Thumann.

12 recordsLinked to original sources
PubMed2006

Effect of photodynamic therapy on the function of the outer blood-retinal barrier in an in vitro model.

BACKGROUND: Photodynamic therapy (PDT) is a well established clinical treatment for age-related macular degeneration (AMD), and comprises intravenous injection of verteporfin and subsequent application of a non-thermal laser beam to the area of AMD to induce selective vascular occlusion. Since there is evidence that PDT may cause outer blood-retinal barrier (BRB) breakdown and possibly RPE cell alteration, we investigated the effect of PDT on the BRB function of the RPE in an in vitro model. METHODS: Twenty-one monolayers of human RPE cells were cultured on semipermeable membranes until a stable barrier function was achieved as determined by transepithelial electrical resistance (TER) and sodium fluorescein permeability. To test the effect of PDT on the outer BRB function, non-thermal laser (692 nm), verteporfin or a combination of both were applied. TER assessment prior to and after PDT was utilized to identify changes in barrier function of the RPE in this in vitro model. Finally, monolayers of RPE cells were evaluated by transmission electron microscopy (TEM). RESULTS: No significant TER decrease was observed after application of non-thermal laser alone or after administration of verteporfin in therapeutic concentrations, but combination of these modalities resulted in significantly decreased TER within 4 h. Except for intercellular blisters, no damage to the RPE was evident in TEM. Verteporfin added at concentrations higher than therapeutic doses (2 mg/ml) resulted in an immediate decrease in TER and damage to the RPE cells. CONCLUSION: The combination of a therapeutic concentration of verteporfin and application of non-thermal laser resulted in a morphologically and functionally detectable breakdown of the outer BRB function of the RPE without any damage to the RPE cells themselves in vitro. However, increasing the concentration of verteporfin can result in RPE cell damage.

Blood-Retinal Barrier↗
PubMed2006

Iris pigment epithelial translocation in the treatment of exudative macular degeneration: a 3-year follow-up.

OBJECTIVE: To report the functional and anatomical outcome of 20 patients who underwent surgical removal of choroidal neovascularization combined with transplantation of autologous iris pigment epithelial cells to the subretinal space 3 years after treatment. METHODS: Freshly isolated autologous iris pigment epithelial cells were translocated to the subretinal space in 20 patients after membrane extraction. Patients were followed up by funduscopy, angiography, microperimetry, and visual acuity testing. RESULTS: After a follow-up of 3 years, 1 patient showed improved visual acuity, 13 patients retained stable visual acuity, and 3 patients had reduced visual acuity. No macular edema or recurrent choroidal neovascularization was apparent at any time during the follow-up. CONCLUSIONS: Transplanted autologous iris pigment epithelial cells were well tolerated for 3 years and stabilization of visual acuity was achieved in most patients. These results suggest that iris pigment epithelial cells may serve as a substitute for retinal pigment epithelial cells after choroidal neovascularization removal in patients with exudative macular degeneration; however, whether these cells will be of any value for the restoration of vision and possible protection against choroidal neovascularization recurrence awaits further clinical observation and additional research.

Adult↗
PubMed2006

Characteristics of iris and retinal pigment epithelial cells cultured on collagen type I membranes.

PURPOSE: Transplantation of pigment epithelial cells is a promising treatment modality to repair retinal damage in age-related macular degeneration. For this purpose, it is necessary to establish cell culture techniques that allow acquisition of proper functional and morphological characteristics by the cells to be transplanted. METHODS: Primary retinal pigment epithelial (RPE) and iris pigment epithelial (IPE) cells grown to confluence on collagen membranes were examined for morphology, adhesion, proliferation, apoptosis, as well as viability after ex vivo transplantation. RESULTS: Pigment epithelial cells adhere, proliferate, form monolayers, acquire differentiated properties, and remain viable during transplantation to the subretinal space. CONCLUSIONS: Pigment epithelial cells cultured on collagen membranes acquire differentiated characteristics and are amenable to be transplanted as cell monolayers.

Animals↗
PubMed2006

Instrumentation and technique for delivery of tissue explants to the subretinal space.

PURPOSE: The controlled orientation of subretinal or intraretinal delivery of delicate tissue sheets is a critical problem in retinal transplantation research. METHODS: A surgical device (explant injector) was designed and built for the controlled delivery of tissue explants into the subretinal or intraretinal space via a vitrectomy approach. The technical feasibility was demonstrated in enucleated porcine eyes. RESULTS: Using negative pressure, the injector allows for the fixation of an explant, such as a monolayer of cells cultured on a collagen membrane, on the carrier platform. The sheet can then be placed safely without loss of orientation in the subretinal space. CONCLUSIONS: With the aid of the explant injector, it is possible to deliver an explant with the proper orientation to a precise location in the subretinal space.

Absorbable Implants↗
PubMed2006

Ultrastructural changes after artificial retinal detachment with modified retinal adhesion.

PURPOSE: Artificial retinal detachment is increasingly used in submacular surgery. However, overcoming physiological retinal adhesiveness by subretinal fluid injection is suspected to cause cellular damage and thus to limit visual rehabilitation. This experimental study was designed to examine the ultrastructural changes induced by retinal detachment under vitrectomy conditions and to evaluate factors that reduce adhesiveness and minimize cellular damage. METHODS: Twenty-one pigmented rabbits underwent vitrectomy, and the vitreous cavity was perfused for 10 minutes with various solutions. These included variations in osmolarity (314 and 500 mOsM), Ca(2+) ion concentration (Ca(2+)-supplemented, low Ca(2+), active Ca(2+) deprivation via 1 mM EDTA), temperature (19 degrees C and 34 degrees C), and ischemia (5 minutes). Nonvitrectomized eyes served as the control. Consecutively, an artificial bleb detachment was created underneath the visual streak by injecting 1 mL of buffered saline solution subretinally. Eyes were enucleated within 3 minutes, fixed with 2% glutaraldehyde/0.1 M cacodylate buffer (pH 7.4) containing 100 mM sucrose and processed for transmission electron microscopy and scanning electron microscopy. RESULTS: If a Ca(2+)-containing standard solution was used during vitrectomy, retinal adhesiveness was strong, and a forced bleb detachment caused substantial cellular damage characterized by swollen and fragmented photoreceptor outer segments and disruption of retinal pigment epithelial cells. Use of a Ca(2+)-free solution moderately reduced the adhesive strength with consequently less ultrastructural damage. Active Ca(2+)-deprivation further reduced the retinal adhesion, but may have induced damage as suggested by intracellular vacuolization. Hyperosmolarity and ischemic conditions had toxic effects on both the photoreceptors and RPE cells. In contrast, the use of a preheated Ca(2+)-free solution (34 degrees C) substantially reduced retinal adhesiveness under vitrectomy conditions and hence ultrastructural damage. CONCLUSIONS: Artificial retinal detachment causes substantial ultrastructural damage in eyes with physiological retinal adhesiveness if performed under vitrectomy conditions similar to surgery in humans. The use of a preheated Ca(2+)-free physiologic saline solution seems to be suitable to reduce retinal adhesion sufficiently, without causing significant cellular damage.

Adhesiveness↗
PubMed2005

A comparison between IV paracetamol and IV metamizol for postoperative analgesia after retinal surgery.

OBJECTIVE: To assess clinical efficacy of IV paracetamol 1 g and IV metamizol 1 IV metamizol 1 g on a 24-h dosing schedule in this randomized, double-blinded, placebo-controlled study of 38 ASA physical status I-III patients undergoing retinal surgery. RESEARCH DESIGN AND METHODS: General anaesthesia using remifentanil, propofol, and desflurane was performed for surgery. The patients were randomly allocated to three groups, receiving infusions of paracetamol 1 g/100 mL (Para Group), of metamizol 1 g/100 mL (Meta Group), or of 100 mL of saline solution as placebo control (Plac Group) 30 min before arrival in the recovery area and every 6 h up to 24 h postoperatively. All patients had unrestricted access to intravenous opioid rescue medication. MAIN OUTCOME MEASURES: The primary efficacy variables were pain scores at rest over 30 h postoperatively analysed by using repeated ANOVA measurement. Secondary efficacy variables were pain scores on coughing, also analysed by repeated ANOVA measurement. RESULTS: Five patients in the Plac Group and one patient in the Meta Group interrupted the study protocol. Regarding pain scores at rest, Mauchly-test of sphericity was significant (p = 0.03). For the p time effects a significant result was detected (p < 0.001). The main effect between the three treatment groups was significantly different (p = 0.01). The Bonferroni adjusted pair wise comparisons between p the Plac Group and the Para Group showed a significant difference in favour of IV paracetamol (p = 0.024; mean difference 14.8; p 95% CI 1.6-28.0), between the Plac Group and the Meta Group in favour of IV metamizol (p = 0.025; mean difference 14.4; 95% CI p 1.5-27.4), and no significant difference between the Para Group and the Meta Group (p = 1.0; mean difference 0.4; 95% CI-12.8 to 13.6). Pain scores on coughing showed a significant different main effect between the three treatment groups (p = 0.022). The Bonferroni adjusted pair wise comparisons between the Plac Group and the Para Group showed a significant difference in favour of IV paracetamol (p = 0.032; mean difference 17.9; 95% CI 1.3-34.6), a p difference, though not reaching statistical significance, in favour of IV metamizol between the Plac Group and the Meta Group (p = 0.081; p mean difference 15.0; 95% CI -1.4 to 31.4), and no significant difference between the Para Group and the Meta Group (p = 1.0; p mean difference 2.9; 95% CI -13.8 6 to 19.6). None of the patients experienced itching; one patient in the Meta Group developed a mild erythema. There was no statistical difference in the incidence of nausea (Plac vs. Para Group: p = 0.94, Plac vs. Meta Group: p = 0.98, Para vs Meta Group: p = 0.95) or vomiting (Plac vs. Para Group: p = 0.73, Plac vs. Meta Group: p = 0.85, Para vs Meta Group: p = 0.86) between the groups. Patients in the Plac Group experienced significantly more often sedation than patients in the Meta Group (p = 0.049). There was a trend of higher sedation in the Plac Group than in the Para Group, which did not reach statistical significance (p = 0.07). There was no difference in sedation between the Meta and the Para Groups (p = 0.84). CONCLUSION: IV paracetamol 1 g has a similar analgesic potency as IV metamizol 1 g for postoperative analgesia after retinal surgery.

Acetaminophen↗
PubMed2003

Outcome of combined penetrating keratoplasty with vitreoretinal surgery for management of severe ocular injuries.

PURPOSE: To assess the effectiveness of a combined procedure (pars plana vitrectomy with temporary keratoprosthesis, vitreoretinal surgery, and penetrating keratoplasty) and to determine which factors influence corneal transplant success rates. METHODS: Records for 34 severely injured eyes of 31 consecutive patients who underwent penetrating keratoplasty in combination with vitreoretinal surgery between 1991 and 1998, with a follow-up of at least 12 months, were evaluated retrospectively. Analysis was focused on ocular history, functional and anatomic anterior and posterior segment outcome, and complications. RESULTS: Penetrating keratoplasty was performed in 10 eyes (29%) within 8 weeks of trauma and in 24 eyes (71%) as a secondary procedure. Initial improvement in visual acuity (VA) was achieved in 47% of eyes; at the end of the follow-up, 74% of the eyes had attained equal or better VA than the initial postsurgical VA. Reasons for poor final VA were hypotony or phthisis (35%) and recurrent retinal detachment (11%). Corneal grafts remained clear for 1 year in 65% of eyes. Transplant failure was less in eyes that did not need a permanent silicone oil tamponade, when the retina was attached before surgery, and in eyes that were grafted later after trauma and received no further surgery. These were some conditions that were associated with a longer mean graft survival time, but without statistical significance. There was no difference in eyes according to the trauma mechanism, preoperative intraocular pressure, or graft size. CONCLUSIONS: Penetrating keratoplasty in severely injured eyes is often complicated by ciliary body malfunction and secondary transplant failure. Although the functional outcome of a combined procedure is limited by primary and secondary tissue destruction, preserving ambulatory vision is possible and thus improves the quality of life, at least in patients with single remaining eyes.

Adolescent↗
PubMed2002

Combined penetrating keratoplasty and vitreoretinal surgery with silicone oil: a 1-year follow-up.

BACKGROUND: The aim of this study was to assess the functional outcome of eyes with corneal and vitreoretinal diseases following combined surgical procedures (pars plana vitrectomy with temporary keratoprosthesis, vitreoretinal surgery, and penetrating keratoplasty with intravitreal silicone oil tamponade) and to evaluate the factors preserving the clarity of grafts. METHODS: Fifty-three eyes from 49 consecutive patients, operated on between 1991 and 1998 and followed up for at least 12 months, were evaluated retrospectively. The evaluation focused on ocular history, visual acuity (VA), intraocular pressure, anterior and posterior anatomical outcome, and complications. RESULTS: The average follow-up was 28.4 months+/-18.8 months (range 12-84 months); at the final visit 58% of the eyes had better VA, and 73% had equal or better acuity; the cornea remained clear in 68% of the eyes. A decrease in VA was caused by: loss of light perception in 2 eyes, one of which had to be enucleated because of painful phthisis; hypotony or phthisis in 23 eyes; recurrent retinal detachment in 4 eyes that were operated because of trauma; and immunological reaction in 2 eyes. Preoperative factors that contributed to a clear graft, but were not significant, were: lack of trauma (74%), no actual silicone oil filling (78%), preoperative VA of hand movement or better (79%), and attached retina (73%). Further surgery was needed in 55% of cases. The risk of transplant failure was significantly lower in eyes that did not undergo additional surgery (p=0.0001). CONCLUSION: The long-term results of combined surgery with penetrating keratoplasty in eyes that would otherwise be untreatable is often limited by anterior segment complications, mainly secondary graft failure and ciliary body malfunction. For optimal preservation of graft clarity, stable ocular status should be achieved before transplantation to minimize the necessity for further surgery.

Adolescent↗
PubMed2002

Macular translocation with 360 degrees retinotomy for exudative age-related macular degeneration.

BACKGROUND: Macular rotation surgery comprises surgical extraction of choroidal neovascular membranes in age-related macular degeneration (AMD) and translocation of the foveal neural retina over adjacent retinal pigment epithelium. OBJECTIVE: To determine whether macular translocation with 360 degrees retinotomy can stabilize and/or improve visual acuity in patients with subfoveal choroidal neovascularization (CNV) secondary to AMD. DESIGN: This study consisted of a standardized surgical procedure on a series of 90 consecutive patients and follow-up examinations at fixed intervals for 12 months. PARTICIPANTS: All patients in this study had experienced recent visual loss resulting from subfoveal CNV caused by AMD. Twenty-six patients had major macular subretinal hemorrhage, 39 patients had occult subfoveal CNV, and 25 patients had classic subfoveal CNV. METHODS: Macular translocation surgery was performed between 1997 and 1999. The patients were examined preoperatively and at 3, 6, and 12 months postoperatively, including visual acuity, microperimetry, angiography, and orthoptic assessment. RESULTS: Visual acuity increased by 15 or more letters in 24 patients, remained stable in 37 patients, and deteriorated by 15 or more letters in 29 patients at 12 months postoperatively. A secondary procedure was necessary in 17 patients because of severe complications; proliferative vitreoretinopathy was observed in 17 eyes, macular pucker in 5 eyes, and macular hole in 1 patient. CONCLUSION: Macular translocation is a technically demanding surgical procedure. 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↗
PubMed2002

Vitreous treatment of cultured human RPE cells results in differential expression of 10 new genes.

PURPOSE: To analyze the differential gene expression in cultured human retinal pigment epithelial (RPE) cells after treatment with vitreous. METHODS: Cultured human RPE cells were incubated for 48 hours with 25% human vitreous from donor eyes. Total RNA from treated and untreated cells was extracted. The gene expression was analyzed by differential expression analysis (DEmRNA-PCR). The differentially expressed genes were identified by gene bank searches. Differential expression was verified by a quantitative real-time RT-PCR fluorescent nucleic acid staining system. The in vivo mRNA expression of these genes in RPE cells was shown by gene-specific RT-PCR. RESULTS: Vitreous treatment of human RPE cells resulted in the reduced expression of NFIB2, KE03 (NY-REN-25ag), PIG-B, DKFZp564BC462, LKHA, G3BP, PAM, UEV-1, and MAP1B calibrated to the expression of GAPDH when compared with their expression in untreated cells. The reduced expression after vitreous treatment was quantified by gene-specific quantitative real-time RT-PCR and varied from 0.69 to 0.17 compared with untreated cells. The mRNA expression of UDP-GalNac mRNA remained constant. The mRNA expression of eight of these genes was demonstrated in this study for the first time in human RPE cells. CONCLUSIONS: Vitreous treatment of cultured RPE cells induces the differential expression of a variety of genes with functions in transcription, mediation of signal transduction and inflammation, glycosylation, ubiquitination and protein-protein interaction. Further examination of these genes may locate additional targets for treatment of diseases caused by contact of RPE cells with vitreous, typical in proliferative vitreoretinopathy.

Cells, Cultured↗