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Biomedical subjects

K Heimann

Publications and source records attributed to K Heimann.

227 records · Page 13Linked to original sources
PubMedDate not supplied

Basic fibroblast growth factor mRNA, bFGF peptide and FGF receptor in epiretinal membranes of intraocular proliferative disorders (PVR and PDR).

Basic fibroblast growth factor (bFGF) has been shown to be involved in epiretinal membrane formation in proliferative vitreoretinal disorders. However, up to now, little knowledge exists; as to the actual cellular source of this potent mitogen. We examined 20 epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) (n = 12) and proliferative vitreoretinopathy (PVR) (n = 8) for the presence of bFGF peptide, fibroblast growth factor receptor-1 (FGFR-1) and bFGF messenger ribonucleic acid (mRNA). Using a specific antibody, we detected bFGF peptide in most (8/10) examined PDR membranes and in all (8/8) PVR membranes. Moreover, we found positive staining for the corresponding receptor. Local production of bFGF in epiretinal membranes was confirmed by nonisotopic in situ hybridisation for bFGF mRNA in some (4/7) examined PDR membranes and some (3/4) examined PVR membranes. All membranes which contained bFGF mRNA were also positive for bFGF peptide. In conclusion, bFGF is produced and stored in epiretinal membranes. Together with the corresponding receptor, bFGF may play a role in the auto- and paracrine control of the proliferative processes at the vitreoretinal interface.

Adult↗
PubMedDate not supplied

Immunohistochemistry of anterior proliferative vitreoretinopathy. Report of 11 cases.

Anterior proliferative vitreoretinopathy is characterized by epiretinal proliferation that extends anteriorly over the vitreous base, and may, in addition to the cells usually contributing to proliferative vitreoretinopathy, also contain cells of ocular structures located in that area. We examined 11 complete globes with aPVR that were enucleated after previous severe trauma or perforating injuries (n = 8) and complicated retinal detachment (n = 3) by a panel of immunohistochemical markers. We found presence of RPE, glial cells, macrophages and fibrocytes, as consistently reported in PVR membranes. In addition, T-cell lymphocytes were present in 6 of the cases, and cells expressing the common leucocyte antigen on 8 cases. Cells staining positive for the intracytoplasmic contractile filament alpha-smooth muscle actin were present in 5 cases and cells staining for desmin in one case. Collagen type IV was part of most of the membranes, and vessels with leakage of plasma factors were present in more than half of the cases.

Adult↗
PubMedDate not supplied

Immunohistochemistry of cellular proliferation in eyes with longstanding retinal detachment.

To further characterize the content and nature of cyclitic membranes (n = 4), ringschwielen (n = 3) and a subretinal strand on sections of complete globes with long-standing retinal detachment after trauma (n = 7) or retinal reattachment surgery (n = 1), we applied a panel of cellular and extracellular antibodies using the APAAP (alkaline phosphatase and monoclonal anti-alkaline phosphatase) technique. Only one cyclitic membrane from an eye that was enucleated two months after trauma was positive for glial fibrillary acidic protein, demonstrating the presence of glial cells. All cyclitic membranes contained macrophages and expressed intracellular contractile proteins. Ringschwielen stained consistently for cells of epithelial origin (RPE) with cytokeratin and for macrophages. The subretinal strand stained for cytokeratin, macrophages and alpha-smooth muscle actin, supporting cellular contraction in the genesis of this form of proliferative vitreoretinopathy.

Adult↗
PubMedDate not supplied

Primary use of silicone oil tamponade in the management of perforating globe injury secondary to inadvertent local anaesthesia injection for ophthalmic surgery.

Perforating and penetrating globe injuries secondary to peribulbar and retrobulbar anaesthesia are often complicated by vitreous haemorrhage and retinal detachment. We describe the effectiveness of primary silicone oil tamponade in the repair of three perforated globes secondary to local anaesthesia for ophthalmic surgery. Three patients with axial myopia had peribulbar and retrobulbar anaesthesia for extracapsular cataract extraction (two patients) and cryotherapy (one patient). All eyes sustained a vitreous haemorrhage obscuring the view to the fundus. Retinal detachments were detected by B-scan ultrasound. In all eyes, scleral buckling, pars plana vitrectomy and silicone oil tamponade were performed as a primary surgical procedure. All the patients had complete anatomic reposition. In two patients, after two years follow-up, visual acuity was between 6/12 to 6/36 with the retina attached and no proliferative vitreoretinopathy (PVR). The third patient had blind painful eye and enucleation was performed. Primary use of silicone oil tamponade, in the management of perforated globe with retinal detachment due to local anaesthesia injection, is recommended.

Adult↗
PubMedDate not supplied

Subretinal injection of rod outer segments leads to an increase in the number of early-stage melanosomes in retinal pigment epithelial cells.

Our study was performed to test the hypothesis that subretinally injected protein can induce melanogenesis in the retinal pigment epithelium (RPE). Rod outer segments (ROS) were isolated from cattle eyes and injected into the subretinal space of Long Evans rats. Five days after surgery, the injected eyes were investigated by electron microscopy. The number of early-stage melanosomes and small melanin granules was compared in injected and noninjected eyes. It was found that the injected ROS were phagocytized by the RPE cells, and the number of early-stage melanosomes in the RPE was significantly increased in injected eyes compared to eyes without injection. The ROS-containing endosomes fused with melanolysosomes in which melanogenesis took place. The increased number of early-stage melanosomes indicates new formation of melanin.

Animals↗
PubMedDate not supplied

Functional results after vitrectomy with silicone oil injection.

In a prospective study we investigated the visual acuity and differential light sensitivity in 39 patients (40 eyes) with reattached macula. One group, treated with an encircling band (21 eyes), was compared to another, where vitrectomy and silicone oil injection had been necessary (19 eyes). Intraoperatively 9 of the vitrectomized eyes received an infusion of daunomycin (7.5 mg/l for 10 min). On average the vitrectomized eyes had a greater loss of visual acuity and differential light sensitivity. In all groups we found a positive correlation between visual acuity and the differential light sensitivity. At the same visual acuity we did not find any obvious difference in sensitivity between the groups. Correlation and regression line were similar for both groups. The mean relative sensitivity was lower in the fovea than in the rest of the tested field. A selective effect of silicone oil on either spatial resolution or differential light sensitivity could not be verified. The intraoperative application of daunomycin had no influence on the functional results.

Adolescent↗
PubMedDate not supplied

Mononuclear phagocytes in proliferative vitreoretinopathy (PVR). A specific role of microglial cells in non-traumatic disease?

Mononuclear phagocytes have been a focus of attention in the cellular biology of proliferative vitreoretinopathy (PVR) for more than ten years. The pattern of phagocyte participation in periretinal traction membrane formation in PVR depends on the etiology, i.e. trauma, rhegmatogenous retinal detachment, previous therapy, i.e. multiple surgical interventions, and the clinical stage of the disease. We have recently identified microglial cells as a distinct cellular population, in membranes from patients with non-traumatic PVR. Current evidence of mononuclear phagocyte function in PVR suggests a role for resident phagocytes of the vitreous and retina in PVR subsequent to rhegmatogenous detachment, and a role for blood-derived monocytes in post-traumatic PVR. The cellular biology of PVR may be much more heterogeneous than previously assumed.

Diabetic Retinopathy↗
PubMedDate not supplied

Thrombospondin: a new attachment protein in preretinal traction membranes.

Thrombospondin (TSP), an adhesive integrin-binding protein of plasma and platelets, was detected in preretinal traction membranes from patients with idiopathic (8/8) and traumatic (7/8) proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR) (6/8). TSP immunoreactivity was compared to the pattern of von Willebrand factor, plasma transglutaminase (blood coagulation factor XIII), fibronectin, and mononuclear phagocytes, using double-label immunofluorescence microscopy. TSP was partially colocalised with the endothelial cell marker, von Willebrand factor, in PDR. The codistribution of catalytic factor XIII and two cross-linking substrates, fibronectin and TSP, suggests a functional role of the enzyme in the extracellular matrix build-up in PVR and PDR. No significant TSP synthesis by mononuclear phagocytes was observed. Western blotting indicated a plasmin-mediated intravitreal breakdown of presumably plasmatic TSP in PVR and PDR.

Antibodies, Monoclonal↗
PubMedDate not supplied

Vitreous changes and retinal detachment in highly myopic eyes.

This report on 496 highly myopic eyes that underwent transcleral or vitreoretinal surgery for retinal detachment (RD) focuses particularly on how changes in the vitreous gel and the resulting modifications of the vitreoretinal interface produce typical characteristics and complications. According to the pattern of vitreous modifications the 496 eyes were divided into five groups: 1) eyes with uniform PVD (108 eyes) 2) eyes with PVD spreading towards the upper quadrants (231 eyes) 3) eyes with extensive vitreous liquefaction (EVL) and condensations of the vitreous base (51 eyes) 4) eyes with posterior vitreous lacuna (PVL, 87 eyes) 5) eyes with very limited PVD (19 eyes). Age, degree of myopia, surgical procedures and final results are reported for each group. A strong correlation was observed between vitreous changes and clinical picture of RD especially in the group of PVL and EVL. In the PVL group a higher degree of myopia was found and more pronounced posterior staphyloma. Frequently the posterior hyaloid, in the form of a thin, extremely smooth membrane, was hard to separate from the inner posterior retina during surgery. Posterior retinal breaks, including macular holes, were found in 56% of eyes. The presence of EVL with condensation of the vitreous base was correlated with giant retinal tear (GRT) in 70% of cases (36 of 51 eyes). Sixteen GRT were also found in the group of uniform PVD, but these were less extensive and located more posteriorly than in the EVL group. In the former group there were better surgical results because of a lower incidence of PVR. In 46% of the eyes of our series (group 2), PVD extended mostly in the upper quadrants with no vitreous detachment inferiorly. In these cases there was a clinical appearance of inferior vitreous collapse. These eyes had 92% of peripheral superior retinal breaks. Relapses of RD in this group almost invariably occurred in the inferior quadrants.

Adolescent↗
PubMedDate not supplied

[Prevention of secondary cataract by intracapsular administration of the antimitotic daunomycin].

Pharmacological inhibition of capsule opacification e.g. using antimitotics such as daunomycin is a promising concept. Our own in vitro studies on cultured porcine lens epithelial cells have shown, that daunomycin penetrates the cells within at least 5 minutes. It possesses a low acute cytotoxicity and significantly inhibits epithelial cell proliferation at dose dependent concentrations ranging from 2.5 to 7.5 mg/l. In addition, in vitro studies on isolated pig corneas showed almost no corneal endothelial toxicity. After 10 resp. 30 min. exposure to 7.5 mg/l daunomycin, there was only 4.8 +/- 1.6 resp. 6.1 +/- 1.5% endothelial damage that dit not significantly differ from BSS serving as control. Encouraged by our clinical experience of good anterior segment tolerance of 7.5 mg/l daunomycin when used during vitrectomy in PVR, we started a prospective clinical trial to assess the effect to daunomycin on capsular opacification after ECCE with endo-capsular IOL implantation using the envelope technique. After agreement of the medical ethic commission we chose 6 patients with a mean age of 78 (72-83), no other ocular or general diseases and bilateral cataract of identical morphology and density. After written consent of the patients their first eye was operated using BSS as control. At least 4 weeks later the second eye was operated and received 0.5 ml of daunomycin (7.5 mg/l) applied during 5 minutes into the cleaned capsular bag, leaving the anterior capsular flap and a Healon filled anterior chamber to protect the surrounding intraocular structures. Mean postoperative control time actually is 12 (6-17) months for the controls and 10 (5-14) months for the eyes treated with daunomycin.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗