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Biomedical subjects

M Weller

Publications and source records attributed to M Weller.

At least 325 records · Page 18Linked to original sources
PubMed1989

[In vitro changes in the lens epithelium and corneal endothelium caused by the cytostatic drug daunomycin].

We evaluated the effects of the antiproliferative drug daunomycin on the viability and proliferation of cultured porcine lens epithelial cells. After a single short-term application, daunomycin penetrates the lens epithelial cells within 5 min. At a concentration of 2.5-7.5 mg/l, daunomycin has a low level of acute cytotoxicity and significantly suppresses the mitotic activity of the epithelial cells in culture. The daunomycin-induced endothelial lesions in freshly excised pig corneas were quantified with the Janus green photometry technique (n = 30) and studied with scanning electron microscopy (n = 9) in comparison to Ringer solution, which served as the control (n = 39). Whether the endothelial lesions were exposed to daunomycin or Ringer solution for 10 or 30 min seemed to make no significant difference. In addition, daunomycin did not seem to induce any morphological changes in the endothelial surface. These in vitro results confirm our clinical experience that daunomycin is apparently not harmful to the adult human corneal endothelium. Our results indicate that short-term endocapsular application of daunomycin during extracapsular cataract extraction, with or without IOL implantation, may prevent and/or delay the formation of capsular opacification.

Animals↗
PubMed1989

[Isoelectric focusing and electroblotting of human vitreous body proteins].

Due to its high resolution and reproducibility, isoelectric focusing with a highly sensitive silver stain, in combination with electroblotting and immunodetection, may be a valuable technique to provide detailed mapping of the protein pattern of the human vitreous. By means of this technique, the presence of albumin, alpha 1-antitrypsin, alpha 1-acid glycoprotein, and transferrin in the normal human vitreous was established. Our results indicate that the differences between vitreous protein und serum protein are more of a quantitative than a qualitative nature. Preliminary studies on pathological vitreous samples obtained during vitrectomy indicate that a substantial amount of the intravitreal protein in PVR as well as in proliferative diabetic retinopathy is plasma-derived. The vitreous from eyes with a macular pucker shows a pattern of protein bands that is reminiscent of normal vitreous.

Eye Proteins↗
PubMed1988

Expression of human tyrosine hydroxylase cDNA in invertebrate cells using a baculovirus vector.

A human cDNA containing the complete coding sequence for a human tyrosine hydroxylase (EC 1.14.16.2, form 2) was introduced into the genome of Autographa californica nuclear polyhedrosis virus (AcNPV) downstream to the polyhedrin promoter. Infection of Spodoptera frugiperda cells (SF9) with recombinant virus resulted in the expression of human tyrosine hydroxylase in these invertebrate cells. Characterization of tyrosine hydroxylase activity in infected SF9 cells demonstrated both substrate and cofactor kinetics that were characteristic of those previously reported for the native human enzyme. Both 3-iodotyrosine and alpha-methyl-p-tyrosine competitively inhibited the recombinantly produced tyrosine hydroxylase with Ki values of 1.2 and 16 microM, respectively, similar to those previously reported for the rat and human enzymes. Western blot analysis of extracts of SF9 cells infected with the recombinant baculovirus containing human tyrosine hydroxylase cDNA revealed a major immunoreactive band with an apparent Mr of 60 kDa, identical to the size of the immunoreactive protein from rat adrenal and caudate nucleus. The use of the baculovirus expression system to produce abundant quantities of each of the multiple forms of active human tyrosine hydroxylase in eukaryotic cells should facilitate structural analysis and help clarify the physiological significance of each of the isoenzymes.

Base Sequence↗
PubMed1988

Immunochemical studies of epiretinal membranes using APAAP complexes: evidence for macrophage involvement in traumatic proliferative vitreoretinopathy.

Proliferative vitreoretinopathy is characterized by cellular proliferations in the periretinal space resulting in traction retinal detachment. Numerous cellular elements and connective tissue components have been identified by morphologic criteria as well as immunochemical techniques. In this study, we used the recently introduced APAAP (alkaline phosphatase - anti-alkaline phosphatase) immunostaining procedure to identify macrophages, T-lymphocytes, the structural proteins fibronectin, vimentin, and cytokeratin, and a proliferating cell antigen, in eleven human epiretinal membranes obtained during vitreoretinal surgery. Our results confirm that the pathologic processes in PVR are not immunologically mediated, but reveal the features of physiologic wound healing and scar formation. Posttraumatic PVR seems to be characterized by a severe initial inflammatory reaction as evidenced by the presence of numerous macrophages, whereas idiopathic PVR, as a complication of retinal detachment, may be caused by different mechanisms in the early pathogenesis.

Alkaline Phosphatase↗
PubMed1988

Evaluation of daunomycin toxicity on lens epithelium in vitro.

Posterior capsule opacification is the major complication of extracapsular cataract extraction (ECCE). Lens epithelial cells derived from the periphery of the lens are thought to migrate posteriorly and contribute significantly to the postoperative proliferations at the posterior pole. We have evaluated the effects of the antiproliferative drug daunomycin on cultured porcine lens epithelial cell viability and proliferation. We observed that the mitotic activity of the cells is suppressed by a single short time treatment with daunomycin at a concentration as low as 2.5 mg/l. Long term effects on the reproductive capacity of the lens epithelial cells may not be as pronounced as the inhibition of other cells examined before e.g. retinal pigment epithelium and fibroblasts. Our results indicate that daunomycin may be useful for the pharmacologic prevention of postoperative proliferations in patients treated by ECCE.

Animals↗
PubMed1988

Fibronectin quantification in plasma and vitreous by a noncompetitive ELISA technique.

Fibronectin, a high-molecular glycoprotein of the extracellular matrix and plasma, has provoked increasing interest in ophthalmology because of its possibly important role in the pathogenesis of proliferative vitreoretinopathy (PVR). A quantitative determination of fibronectin in vitreous aspirates is necessary for the evaluation of this glycoprotein in PVR. A noncompetitive enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of immunoreactive fibronectin in human plasma samples and vitreous aspirates. Here, procedures to establish an ELISA for the clinical laboratory routine are discussed and possible pitfalls during the assay standardization are described.

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

Demonstration of mononuclear phagocytes in a human epiretinal membrane using a monoclonal anti-human macrophage antibody.

Proliferative vitreoretinopathy (PVR), the major complication of rhegmatogenous retinal detachment and posterior segment ocular trauma, is a multistage disease process eventually resulting in traction retinal detachment. The migration of macrophages to a site of disrupted barriers between the vitreous, retina, and choroidea, respectively, is considered to be an important step in the early pathogenesis of PVR. In this study, we demonstrate the presence of numerous mononuclear phagocytes in a human PVR membrane by an APAAP (alkaline phosphatase-anti-alkaline phosphatase) immunostain using a monoclonal mouse anti-human macrophage antibody. This finding correlates with a highly positive fibronectin immunostain in the same specimen. Our results warrant further investigation of the involvement of mononuclear phagocytes in vitreoretinal proliferative disorders.

Antibodies, Monoclonal↗
PubMed1988

The significance of fibronectin in vitreoretinal pathology. A critical evaluation.

Proliferative vitreoretinopathy (PVR) is characterized by cellular proliferation and the formation of intravitreal and periretinal membranes predisposing to traction retinal detachment. Recently, fibronectin, a high-molecular glycoprotein, has been attributed an important role in the pathogenesis of PVR. In order to evaluate the significance of fibronectin as a diagnostic order prognostic marker for PVR, we determined levels of immunoreactive fibronectin in 59 human vitreous specimens by a noncompetitive ELISA technique. Before this study, fibronectin levels in the vitreous had not been investigated taking both protein and iron levels into consideration. The vitreous was obtained during vitrectomies performed for a broad spectrum of vitreoretinal disorders. Our measurements suggest that the amount of intravitreal fibronectin may be correlated with the severity of a manifested disorder rather than being diagnostic for PVR. As long as plasma-derived fibronectin cannot be differentiated from other tissue fibronectins, however, the concentration of this glycoprotein is not a reliable indicator of intraocular proliferative activity. The values for all three parameters--fibronectin, protein, and iron--were significantly higher in revitrectomy samples compared to patients undergoing a first vitrectomy. A somewhat surprising result was a high level of fibronectin in the vitreous of two patients with macular pucker.

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

[Traction detachment in Coats disease].

Immunocytochemical examination of a subretinal membrane removed during vitrectomy from a patient suffering from Coats' disease revealed macrophages, fibronectin, and vimentin. Vimentin is considered to be a marker of mesenchymal cells. Fibronectin may represent a guide rail and scaffold for the cellular organization of subretinal exudates.

Fibronectins↗
PubMed1988

[Role of macrophages and fibronectin in vitreoretinal proliferation].

Proliferative vitreoretinopathy (PVR) is characterized by the periretinal proliferation of nonneoplastic cells complicated by traction retinal detachment. In this study, we report the demonstration of macrophages, which are thought to be involved in the etiology of this intraocular disease, in human periretinal membranes by an immunochemical staining procedure using a monoclonal anti-human macrophage antibody. Fibronectin, a high-molecular protein of plasma and extracellular matrix, may be visualized accordingly and could act concomitantly with macrophages as an important factor in PVR. Fibronectin is shown to be present in high quantities (Elisa) in vitreous aspirates from patients with PVR. We hypothesize that the interaction of macrophages and fibronectin may be a crucial step in the development of PVR.

Cell Division↗
PubMed1987

Cytotoxic effects of daunomycin on retinal pigment epithelium in vitro.

Proliferative vitreoretinopathy (PVR), the most severe complication of retinal detachment surgery and posterior segment ocular trauma, is characterized by the intraocular proliferation of non-neoplastic cells with formation of vitreal and periretinal membranes resulting in renewed traction retinal detachment. As retinal pigment epithelial (RPE) cells have been shown to play an essential role in the development of PVR, we investigated the acute and chronic effects of daunomycin on the morphology and viability of porcine RPE cells in vitro. The intense and complete inhibition of cell proliferation reported in this study adds to previous evidence that daunomycin may be useful for pharmacological treatment of human PVR.

Animals↗
PubMed1982

Characterization of protein phosphorylation in acetylcholine receptor-enriched membrane preparations from Torpedo fuscomaculata.

When the acetylcholine receptor (AChR) from Torpedo is phosphorylated, ATP is found to bind non-covalently to the preparation. After correction is made for this binding of ATP, the phosphorylation reaction has a Km of 0,16 mM, a pH optimum of 8,6 and reaches maximal activity within 3 min. The intrinsic kinase activity is very specific for the AChR and does not phosphorylate either histones or phosvitin. The only amino acid to be phosphorylated is serine and cyclic GMP causes stimulation of the reaction.

Acetylcholine↗