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Biomedical subjects

R P Franke

Publications and source records attributed to R P Franke.

At least 19 recordsLinked to original sources
PubMed1992

Capillary occlusion and secondary angiogenesis: case report.

The first follow-up control 5 days later (14.1.1990) showed a fresh capillary occlusion with massive red blood cell diapedesis. The arteriolar limb of the capillary is filled with erythrocytes up to the occlusion. Since capillary occlusion probably allowed some plasma flow at first, blood cells distal to the occlusion were washed away. After 53 days (8.3.1990) extravasal cells could no longer be made out. At the upper margin of the image a newly formed capillary loop can be seen. The channel of the old capillary seemed to have disappeared. Seventy-three days after occlusion, on 28th of March, the tip of the capillary, already demonstrated on 8th of March, had further grown distally. The capillary had crossed the neighbouring diagonal capillary. Twelve days later (9.4.1990) a remarkable growth connected with formation of a collateral was observed. The new capillary grew in direction of the former capillary channel. On 22nd of April the new capillary had almost got back to its old form. The collateral vessel formed on 9th of April had also grown and could be well distinguished. The different branches were immediately well perfused (mean erythrocyte velocity is v = 0.74 mm/s). The capillary were growing at different speeds. The new capillary had visibly grown by 220 microns over a period of 47 days which corresponds to an average growth of 4.7 microns a day. The capillary was growing fastest between the 9th and 22nd of April. A minimum of growth of 2 microns was observed within the first 11 days of the observation period.

Adult↗
PubMed1989

Induction by sodium butyrate of cytomegalovirus replication in human endothelial cells.

Cultured endothelial cells are shown to be induced in regard to permissiveness to human cytomegalovirus by temporary treatment postinfection with sodium butyrate (1-2 mM). Drug-treated cells are demonstrated to exhibit expression of immediate early and early viral antigens, synthesis of viral DNA and viral structural glycoprotein B. Progeny virus could be visualized by electron microscopy.

Antigens, Viral↗
PubMed1989

[The filter effectiveness of common 15-micron filters (DIN 58362). II: Scanning electron microscopy and roentgen analysis].

When i.v. solutions are used, millions of foreign particles are washed into the organism. Our town studies could recently show that these particles may interact with the organism and thus cause injury. A new method is introduced here (energy dispersive X-ray analysis in scanning electron microscopy, SEM, Jeol 35 CF/EDX, EEDS II Ortec), with which the element combination of foreign particles can be analyzed qualitatively and quantitatively. As a first step an analysis of the particulate matter in filtrates of infusion solutions was carried out in the same way, materials used in infusion therapy (e.g. infusion sets, cannulas, etc.) were analyzed. The results show that most of the particulate matter consists of glass from ampoules, plastic materials from infusion sets and rubber from the rubber stoppers of infusion bottles.

Electron Probe Microanalysis↗
PubMed1989

[Particulate contamination of infusion solutions and drug additives within the scope of long-term intensive therapy. 1. Energy dispersion electron images in the scanning electron microscope-REM/EDX].

During use of i.v. solutions, particulate matter may be introduced into the patient. X-ray analyses have shown that the particulate matter consists mainly of glass from ampules, rubber from stoppers of infusion bottles, and plastic from infusion sets. A new method is introduced: scanning electron microscopy-SEM- in combination with energy-dispersive X-ray analysis-EDX. using this technique all foreign particles larger than 0.8 microns can be detected and analyzed in any tissue. Especially in critically ill patients, particularly matter is deposited in the microcirculation of the lung. The particles cause a variety of pathologic changes (formation of thrombi, thromboembolization of the microcirculation, destruction of the vascular endothelium, formation of granulomas and foreign body giant cells). The adult respiratory distress syndrome could be produced or respiratory insufficiency might be aggravated following circulatory shock. It is therefore recommended that terminal in-line filters with small pore sizes be used for all i.v. solutions.

Adult↗
PubMed1989

Role of the endothelial actin filament cytoskeleton in rheology and permeability.

We have provided evidence for the existence of two distinct sets of actin filaments in endothelial cells, the stress fibers, and the peripheral filament band. Both sets of actin filaments also contain myosin, alpha-actinin, and other associated proteins of the contractile apparatus in muscle. We have shown that both systems of actin filaments in endothelial cells can contract. Stress fibers probably serve to prevent the endothelium from hydrodynamic injury and detachment, whereas the peripheral band of actin filaments appears to be important for the regulation of certain aspects of endothelial permeability.

Actin Cytoskeleton↗
PubMed1989

[The significance of laminin for the stability of endothelial-substrate adhesion in rheologic conditions].

The glycoprotein laminin is a component of the extracellular matrix and seems to be of considerable importance for cellular adhesion. In static cell cultures laminin revealed a profound influence on migration and proliferation of cultured endothelial cells. Coating of coverslips with laminin was found to have a profound and long-lasting effect on the adhesiveness of endothelial cells exposed to experimental fluid shear stress. By changing the seeding density of the cells per cm2 we could stimulate endogenous laminin production to a level that increased resistance of the monolayer against rheological shear stress by 200%.

Cell Adhesion↗
PubMed1989

[Particulate contamination of infusion solutions and drug additives in the framework of long-term intensive therapy. 2. An animal model].

When IV solutions are used, particulate matter may be introduced into the patient. Using X-ray studies we could demonstrate particulate matter consisting mainly of glass from ampules, rubber from rubber stoppers of infusion bottles, and plastic material from IV sets. With a recently introduced method of back-scatter pictures in scanning electron microscopy combined with X-ray studies--Jeol 35 CF/EEDS II Ortec (REM EDX)--we analyzed this phenomenon using an animal model (rabbit). It appears that particulate matter is deposited in the interstitial lung tissue and especially the pulmonary microcirculation. Pathogenetic effects could also be demonstrated (formation of thrombi, etc.).

Animals↗
PubMed1989

[Filtering effectiveness of conventional 15 m micron filters (DIN 58362) and newly developed 15 m micron and 5 m micron filters. I: Particle count].

When i.v. solutions are used, a considerable amount of particulate matter is washed into the patient. This particulate matter consists mainly of glass from ampoules, plastic materials from infusion sets, rubber from the rubber stoppers of infusion bottles and various materials, partly derived from the manufacturing process of the solutions. A new method of particle counting is introduced here (modified thrombocyte counter, Becton Dickinson), whereby particulate matter (less than 2 microns, greater 0.8 microns) could be counted for the first time. Using this counting method, the efficiency of the standard filtration (DIN 58362) was tested. Also tested were 2 new final filtration systems (with 15 microns and 5 microns pore-size). All 3 filtration methods were shown to be ineffective; especially small particles (less than 2 microns) cannot be eliminated by these filtration methods.

Drug Contamination↗
PubMed1988

Ultrastructural organization of contractile and cytoskeletal proteins in glomerular podocytes of chicken, rat, and man.

By immunoelectron microscopy the podocyte foot processes of the rat and human kidney have been shown to contain three major proteins of the contractile apparatus in muscle, i.e., actin, myosin, and the Z-line protein, alpha-actinin. Gel electrophoresis and immunoblot analysis of isolated glomeruli suggests that these proteins constitute an important part of the total glomerular protein contents. In the chicken kidney, the plasmalemmal portion of the foot processes that abuts the glomerular basement membrane was specifically labeled with antibodies against chicken gizzard vinculin and talin, two proteins thought to be important for the linkage of actin filaments to the lipid bilayer and to the receptor for fibronectin and laminin. Such a linkage may not only be important for the attachment of actin filaments to the plasma membrane, but could also be of functional significance for restricting the fibronectin-laminin receptor in its lateral diffusion in the plane of the lipid bilayer and to localize it at the basis of the podocytic foot processes. Assuming that actin, myosin, and alpha-actinin are arranged in a way that would allow the foot processes to generate contractile force this filament system might help the glomerular capillaries to resist the high intraluminal hydrostatic pressure as well as to actively modify the surface area for filtration. Vimentin and tubulin, the main protein subunits of intermediate filaments and microtubules, respectively, were confined to the podocyte cell body and the major processes but were virtually absent from the foot processes. This suggests that both proteins and their polymers are not important for the structure and function of the foot processes.

Actinin↗
PubMed1987

Age-dependent variation of T1 and T2 relaxation times of adenocarcinoma in mice.

The T1 and T2 values of adenocarcinoma EO 771 inoculated into the hind leg of mice are characterized and correlated with the histopathologic state of the tumor. Growth-dependent changes (indicated by a T1 of 630-910 msec and a T2 of 68-185 msec) can be separated into four characteristic phases. The increase in relaxation times in the early phases (A and B) is due to an increasing amount of viable tumor tissue relative to normal muscle tissue. In the later phases (C and D), a decline of the relaxation parameters is observed that is parallel to an increase in the fraction of necrotic tissue. By multiexponential analysis, two relaxation components (indicated by and, respectively) for T1 and T2 and the corresponding fractions alpha 1 and alpha 2 can be observed for both tumor and surrounding muscle tissue. A tissue criterion ("magnetic resonance fingerprint") is defined by a combination of these multiple parameters. This criterion allows separation of not only muscle and tumor tissue but also viable (early state) and necrotic (late state) tumor tissue.

Adenocarcinoma↗
PubMed1987

[Endothelial function and arteriosclerosis].

Elevated levels of plasma LDL have been correlated with morphological endothelial damages, e.g. reduced antithrombogenity of endothelial cells. Numerical and functional defects of endothelial cells probably influence the necessary separation of blood fractions from subendothelial tissues in a negative sense. In order to describe an imaginable endothelial dysfunction with respect to LDL transport we examined human umbilical venous endothelial cells (HUVEC) in culture under physiological flow conditions. HUVEC in culture after incubation with a LDL concentration of 100 micrograms/ml medium were exposed to defined levels of physiological shear stress, fixed with formalin and stained with oil-red-O. After documentation of oil-red-O staining with a photomicroscope, the amount of stain has been characterized semiquantitatively with the help of an image-analysis system (IBAS II/Zeiss). HUVEC not exposed to shear stress only showed a marginal oil-red-O staining at the cell surface. If they were exposed to shear stress of 0.5 dyn/cm2 they showed in orthogonal view an average increase of 1.3%, in cross-sectional view an average increase of 0.3%. HUVEC exposed to shear stress of 2.5 dyn/cm2 showed in orthogonal view an average increase of 4.6%, in cross-sectional view an average increase of 8.7%.

Arteriosclerosis↗
PubMed1987

Multicellular bladder tumor spheroids in coculture with human endothelial cell monolayers.

Multicellular tumor spheroids (MCTS) are avascular spherical tumors grown systematically out of single cells in vitro. The coculture of MCTS of the human bladder carcinoma cell line J 82 with confluent human endothelial cell layers serves as a model to study cell-cell interactions as an important feature in hematogenous tumor spread. Basic information is obtained by phase contrast microscopy and histochemistry. More detailed information is given by the application of scanning and transmission electron microscopy. Immunohistochemistry helps to differentiate endothelial cells from tumor cells (factor VIII-related antigen). The application of this coculture model and of the various methods of evaluation enables us to study cell-to-cell contact phenomena systematically.

Carcinoma, Transitional Cell↗
PubMed1986

Vascular endothelial stress fibres: their potential role in protecting the vessel wall from rheological damage.

Confluent monolayers of endothelial cells from the umbilical vein were exposed to two different levels of shear stress, 2 dyn/cm2 (low arterial value) and 0.5 dyn/cm2 (venous levels) for 60 and 120 min. A dramatic increase in stress fibres was only observed at arterial levels of shear stress while venous levels of shear stress had no significant effect on the stress fibre system. In view of our observation that the stress fibres can contract it is suggested that the induced stress fibres can exert tension to resist the shear forces of blood flow and thus prevent the endothelium from hydrodynamic damage or detachment. Thus stress fibre formation may be an important mechanism to prevent the vascular wall from pathologic stimuli which are thought to initiate arteriosclerosis.

Actin Cytoskeleton↗
PubMed1986

Stress fibres (SF) in human endothelial cells (HEC) under shear stress.

Human umbilical veinous endothelial cells are cultured on artificial substrates precoated with extracellular matrix from bovine corneal endothelial cells. These cultural conditions help cells to keep an elevated maintenance level for otherwise unusual time intervals. Integrity of endothelial cell layers is of special interest for nondisturbed blood circulation. Therefore we look after mechanisms of cell--cell and cell--substrate--adherence. Here we focus on stress fibres, microfilaments, which seem to play an important part in cellular adherence phenomena. Since endothelial cells in vivo are constantly shear stressed by the blood stream we investigated cell--substrate interactions in vitro under dynamical conditions with the help of a modified cone--plate rheometer originally designed for hemorheology. It can be demonstrated in these shearing experiments that toxical substances influence the organization of stress fibres.

Actin Cytoskeleton↗
PubMed1986

[Comparative study of low molecular dextran or hydroxyethyl starch as a volume substitute in hemodilution therapy].

Rheological therapy, as an immediate treatment in conjunction with physical therapy and the removal of risk factors, plays a significant role in the management of patients with peripheral vascular disease experiencing reduced walking tolerance. An essential element of rheological therapy is hemodilution. Currently, is still uncertain which plasma substitute solution would be the most appropriate in such cases. This study compared the effectiveness of low molecular hydroxyethyl starch to low molecular dextran during a 16-day hemodilution in combination to physical therapy. The clinical improvement observed with both plasma substitute solutions was comparable, yet in view of the cardiac volume overload, dextran demonstrates greater circulatory stress due to the transient pressure increase and more side effects. For this reason, we prefer to administer low or middle molecular hydroxyethyl starch in the dilution treatment of peripheral arterial occlusive disease as a chronic degenerative vascular disease.

Adult↗