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R Engelhardt

Publications and source records attributed to R Engelhardt.

141 records · Page 8Linked to original sources
PubMedDate not supplied

First experimental and clinical results with transscleral optical coherence tomography.

BACKGROUND AND OBJECTIVE: To evaluate the potentials of optical coherence tomagraphy (OCT) using long wavelength to penetrate highly scattering tissues of the eye and visualize the anterior chamber angle and the ciliary body. METHODS: OCT images were generated by an experimental prototype in enucleated porcine eyes using as light source a superluminiscent diode with a wavelength of 1310 nm and a scan frequency of 60 Hz. The number of lateral scans was variable in a range from 100 to 400. RESULTS: Infrared OCT was able to penetrate the sclera. The anterior chamber angle could be visualized completely and the ciliary body could be identified. However, it was not possible to penetrate the highly reflective iris pigment epithelium. CONCLUSION: The use of infrared OCT allows penetration of the sclera, thus, providing complete visualization of the anterior chamber angle and limited demonstration of the ciliary body. Because of its higher resolution, it may represent an interesting noninvasive alternative to ultrasound biomicroscopy.

Animals↗
PubMedDate not supplied

An instrument for the rapid determination of L-lactate in biological fluids.

An analyzer for lactate has been developed based upon an electrochemical-enzymatic method. It allows the determination of lactate within 2 to 3 minutes after sample collection. The instrument is capable of performing up to 20 measurements per hour. A minimum sample volume of 50 mul is needed. Except for the injection of the sample, all steps of the measurement are automated. The instrument is easy to operate and can also be used by nontechnical staff.

Autoanalysis↗
PubMedDate not supplied

Endotoxin tolerance: regulation of cytokine production and cellular changes in response to endotoxin application in cancer patients.

Endotoxin (lipopolysaccharide, LPS) has the property of inducing tolerance to its own biological effects. This phenomenon has been extensively studied in animal models but only few studies exist on the regulation in humans. Here we describe experiments designed to determine the cytokine regulation and cellular changes in humans during induction of LPS tolerance after repeated LPS injections. Intravenous administration of purified LPS Salmonella abortus equi to cancer patients induces high amounts of circulating tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-8 (IL-8), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF). Repeated injections of LPS at daily intervals resulted in a marked downregulation of the cytokine response and in the case of TNF-alpha, IL-8, G-CSF, and M-CSF the cytokine response was reduced to baseline levels. In contrast, significant increases in serum IL-6 were detected up to day 5 of repeated LPS injections. Hematological changes included transient decreases in WBCs affecting granulocytes, monocytes, and lymphocytes, followed by a marked granulocytosis. The drop in WBCs remained unaltered throughout the 5 day course of repeated LPS injections whereas the granulocyte overshoot recovery diminished gradually. When PBMCs of the cancer patients were restimulated ex vivo a marked enhancement of the capacity to produce TNF-alpha, IL-113, and IL-6 occurred, which is in contrast to the decreasing TNF-alpha serum levels obtained in vivo. In parallel, a shift in monocyte subpopulations from CD14+/CD16- to CD14+/CD16+ cells was observed. The data provide evidence that different mechanisms are implicated in the cytokine downregulation following repeated LPS injections to cancer patients. Furthermore, PBMCs from LPS tolerant patients do not demonstrate a reduction in their capacity to produce cytokines.

Antigens, CD↗
PubMedDate not supplied

Endogenous tumor lectins: overview and perspectives.

Lectins are carbohydrate-binding proteins of non-immune origin that can be assayed as agglutinins. They are potential mediators in recognitive processes and cell adhesion by interaction with glycoconjugates. These functions are areas of particular relevance to tumor growth and metastatic spread. The presence of lectins in tumors has first been inferred by histochemical and cytological methods. The biochemical analysis for lectins with various specificities reveals differences in the lectin profile between tumors of different classes (eg, mammary adenocarcinoma, rhabdomyosarcoma, or teratoma) and of the same class (eg, testicular germ cell tumors) and differences in relation to normal tissues. The presence of endogenous lectins in tumors, their relation to lectins of normal tissues, and their interaction with glycoconjugates of tumors and normal tissues may contribute to an understanding of intercellular interactions during the complex process of metastatic spread, and may allow to establish a new tool for diagnosis and a lectin-based therapy.

Humans↗
PubMedDate not supplied

Characterization of membrane lectins in human colon carcinoma cells by flow cytofluorometry, drug targeting and affinity chromatography.

Flow cytofluorometry and drug targeting with labelled neoglycoproteins are used as tools to probe for membrane lectins in two human adenocarcinoma cell lines. Both cell lines express activities for galactosides, glucosides and fucosides. Affinity chromatography on gels with immobilized sugar leads to purification of an alpha-galactoside-binding protein at an apparent molecular weight of 64 kDa that also binds to lactose, maltose and fucose and exhibits Ca2+-requirement for binding, a beta-galactoside-binding protein without Ca2+-requirement at an apparent molecular weight of 14 kDa, and an alpha-glucosyl-binding protein without Ca2+-requirement at an apparent molecular weight of 34 kDa from both cell lines. The description of membrane lectins, documented here for the first human tumor cell lines, is an initial step towards a lectin-based improvement of the clinical management of human colon adenocarcinoma.

Adenocarcinoma↗