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H P Heidenkummer

Publications and source records attributed to H P Heidenkummer.

23 records · Page 2Linked to original sources
PubMed1991

[Comparative immunohistochemical studies of epiretinal membranes in proliferative vitreoretinal diseases].

Epiretinal membranes are a fibrocellular tissue whose cellular components are macrophages, glial cells, retinal pigment epithelial cells and fibroblasts. In our immunohistochemical study on epiretinal membranes in proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy, macular pucker, uveitis and after intraocular silicone oil tamponade we analyzed the cellular growth patterns of these histogenetically different cell types on serial sections of paraffin-embedded and frozen material. In addition, the topographic distribution of fibronectin was analyzed and the localization of the epidermal growth factor receptor, which is the coreceptor for the transforming growth factor alpha, was examined by staining procedures. We used antibodies against macrophages (Ki-M7), cytokeratin, vimentin, desmin, glial fibrillary acidic protein and against the proliferation antigen Ki-67. The different cell systems often showed cell-type-specific growth patterns causing an "organoid" structure of the epiretinal membranes. Macrophages predominated in membranes of eyes affected by uveitis and after intraocular silicone oil tamponade. The coexistence of macrophages and other cell types within the same area might be explained by intercellular regulatory mechanisms. Fibronectin, which has functions that are important for cell adhesion, migration, proliferation and differentiation, was topographically localized mainly in areas of denser cell populations and within the walls of newly formed capillaries in diabetic membranes. There was no correlation with specific cell types, however. Among the cellular receptors necessary for signal transduction of mitogenic substances, we localized the coreceptor for the epidermal growth factor and the transforming growth factor alpha among actively proliferating macrophages in a PVR membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Division↗
PubMed1990

[Vitrectomy in proliferative diabetic retinopathy. Preoperative factors for surgical procedure and postoperative results].

In this study we evaluated the impact of preoperative factors on the choice of intraocular tamponades (balanced salt solution and gas or silicone oil) and postsurgical visual function in cases of vitrectomy for proliferative diabetic retinopathy. We studied 150 consecutive vitrectomies for proliferative diabetic retinopathy, which were carried out from October 1987 to February 1989. The extent of central or peripheral traction and retinal detachment were found to have a major influence on the choice of intraocular tamponades. Different types of diabetes, renal failure, and the time interval since the last vitreous hemorrhage showed no influence on the choice of intraocular tamponades. Visual acuity was improved after vitrectomy in the group with silicone oil tamponade, as well as in the control group with BSS or gas tamponade. Patients receiving silicone oil had more advanced stages of proliferative diabetic retinopathy and therefore more complicated postsurgical courses. Silicone oil is more likely to be avoided in cases without retinal detachment, where the risk of further vitreous hemorrhage is felt to be low and in cases with complete panretinal photocoagulation. The present study supports the therapeutic value of complete panretinal photocoagulation for proliferative diabetic retinopathy--even in cases where the proliferative retinopathy progresses and a vitrectomy is needed. It is demonstrated that many patients requiring vitrectomy did not receive sufficient photocoagulation earlier.

Adult↗
PubMed1990

[Experimental studies of the so-called emulsification behavior of silicone oil: effect of viscosity].

The stability of intraocularly applied silicone oils plays an important role in their biocompatibility. The clinically used silicone oils are not a unique group of materials. There are important differences regarding viscosity and the amount of low molecular and ionic components. A sign of bioinstability of silicone oils is silicone oil emulsification. According to clinical experience and experimental studies, less viscous silicone oils seem to emulsify earlier then more viscous oils. Therefore, we investigated three highly purified polydimethylsiloxanes with defined physicochemical characteristics and viscosities of 1,000 cs, 5,000 cs and 10,000 cs for their in vitro stability. As detergents, we used fibrin, fibrinogen, gammaglobulins, acidic alpha-1-glycoprotein, very-low-density lipoprotein (VLDL), and serum. The oil with a viscosity of 1000 cs was the most unstable silicone oil whereas the oils of 5,000 cs and 10,000 cs reacted similarly. The most effective detergents were fibrin, fibrinogen and serum-causing emulsification for all silicone oils investigated whereas gamma-globulins, acidic alpha-1-glycoprotein and VLDL only emulsified the less viscous oil of 1,000 cs. Our results show the importance of viscosity for the stability of silicone oils and the effect of biologically potential detergents.

Drug Stability↗