114 results on '"Ralf-Peter Franke"'
Search Results
2. Histological and SEM Assessment of Blood Stasis in Kidney Blood Vessels after Repeated Intra-Arterial Application of Radiographic Contrast Media
- Author
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Philipp Lamby, Alexander Minkow, Stefan Handt, Johannes Falter, Eva-Lotte Schellenberg, Stefanie Graf, Bernhard Hiebl, Silke Haerteis, Ole Gemeinhardt, Anne Krüger-Genge, Bernd Klosterhalfen, Ernst-Michael Jung, Ralf-Peter Franke, Arash Momeni, Lukas Prantl, and Friedrich Jung
- Subjects
acute kidney injury ,nephrotoxicity ,nephropathy ,renal pathology ,iodinated contrast media ,electron microscopy ,Science - Abstract
Background: After application of iodinated contrast media (CM), a pronounced deterioration of the microcirculation in skin and myocardium was reported. Clinically, the repeated application of CM, especially, led to an increase of the renal resistance index (RRI). With respect to the transiency of the RRI increase, it is reasonable to assume that the deterioration of blood flow could be due to transient blood stasis caused by reversible morphologic cell alterations due to osmotic discrepancies between CM and human blood. Therefore, the hypothesis was investigated whether CM are able to induce in vivo such blood stasis and cell deformations in the renal vasculature of well-hydrated pigs. Methods: The in vivo study was performed as a prospective randomized examination to compare the effects of two different CM in 16 pigs (German Landrace). Pigs were randomized to receive either Iodixanol (n = 8), or Iopromide (n = 8). Each animal received 10 injections separated by 5-min intervals via the suprarenal aorta at a rate of 10 mL/s according to the usual procedure during a cardiac catheter examination. Finally, the kidneys were explanted and processed for histology (H & E staining and fibrin staining according to Weigert) as well as for scanning electron microscopy (SEM) with regards to morphologic correlates explaining the changes in the microcirculation. Results: In each of the predefined four categories of vascular diameters, blood stasis were found, but clearly more often after application of Iopromide than after application of Iodixanol (p < 0.001). In addition, Iopromide induced more blood stasis in all of the examined kidney regions compared to Iodixanol (p = 0.0001). There were no obstructive events in the middle cortex following the application of Iodixanol. Except for the region around a puncture channel of a placed-in catheter probe, no fibrin was detected in Weigert’s fibrin-stained samples, neither around the histologically assessed thrombi nor in vessels with blood stasis. Complementary SEM analyses revealed in a few cases only a slight generation of fibrin and thrombi and deformations, such as echinocyte and “box-like” deformations. Conclusions: According to previous in vitro studies, pathological erythrocyte deformations, such as echinocyte and box-like formation of erythrocytes, were observed also in vivo. In addition, blood stasis and/or thrombi could be detected in histological samples from explanted kidneys from young pigs after repeated in vivo administration of CM. In only a few cases, mural platelet aggregates within minimal fibrin meshes occurred only after the application of Iopromide.
- Published
- 2020
- Full Text
- View/download PDF
3. Effects of Radiographic Contrast Media on the Micromorphology of the Junctional Complex of Erythrocytes Visualized by Immunocytology
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Ralf-Peter Franke, Anne Krüger, Tim Scharnweber, Folker Wenzel, and Friedrich Jung
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radiographic contrast media ,Iopromide ,Iodixanol ,erythrocytes ,cytoskeleton ,band 3 ,band 4.9 ,actin ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium—supplied by the left coronary artery—after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton.
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- 2014
- Full Text
- View/download PDF
4. Vascular Endothelial Cell Biology: An Update
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Anne Krüger-Genge, Anna Blocki, Ralf-Peter Franke, and Friedrich Jung
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endothelium ,shear stress ,angiogenesis ,glycocalyx ,thrombosis ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The vascular endothelium, a monolayer of endothelial cells (EC), constitutes the inner cellular lining of arteries, veins and capillaries and therefore is in direct contact with the components and cells of blood. The endothelium is not only a mere barrier between blood and tissues but also an endocrine organ. It actively controls the degree of vascular relaxation and constriction, and the extravasation of solutes, fluid, macromolecules and hormones, as well as that of platelets and blood cells. Through control of vascular tone, EC regulate the regional blood flow. They also direct inflammatory cells to foreign materials, areas in need of repair or defense against infections. In addition, EC are important in controlling blood fluidity, platelet adhesion and aggregation, leukocyte activation, adhesion, and transmigration. They also tightly keep the balance between coagulation and fibrinolysis and play a major role in the regulation of immune responses, inflammation and angiogenesis. To fulfill these different tasks, EC are heterogeneous and perform distinctly in the various organs and along the vascular tree. Important morphological, physiological and phenotypic differences between EC in the different parts of the arterial tree as well as between arteries and veins optimally support their specified functions in these vascular areas. This review updates the current knowledge about the morphology and function of endothelial cells, particularly their differences in different localizations around the body paying attention specifically to their different responses to physical, biochemical and environmental stimuli considering the different origins of the EC.
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- 2019
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5. Influence of Spray-dried Hydroxyapatite-5-Fluorouracil Granules on Cell Lines Derived from Tissues of Mesenchymal Origin
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Tim Scharnweber, Catarina Santos, Maria Margarida Almeida, Ralf-Peter Franke, and Maria Elisabete V. Costa
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Hydroxyapatite ,Spray dried particles ,5-Fluorouracil ,in Vitro cytotoxicity ,Drug delivery system ,Organic chemistry ,QD241-441 - Abstract
In our previous work we described the preparation and characterization of spray dried hydroxyapatite micro granules loaded with 5-fluorouracil (5-FU). These loaded particles are used as a model drug delivery system (DDS). In this study we examined the in vitro response of two cell lines derived from different tissues to 5-FU loaded granules (LG). Both cell lines, either L929 cells of a mouse fibroblast lineage or cells originating from a rat osteosarcoma (ROS 17/2.8) showed a dose dependent decrease in cell proliferation in response to 5-FU-, either dissolved in the culture medium or loaded onto particles. The response of the two cell lines to loaded and nonloaded particles was different. The effect of LG and of a corresponding concentration of free 5-FU was practically the same for the ROS 17/2.8 cells indicating that ROS 17/2.8 cells were not affected by the carrier material. In contrast, L929 cells showed a slight decrease in cell proliferation also in the presence of granules not loaded with 5-FU. This is thought to be attributed to the inhibition of mitogenesis by phosphocitrates, already demonstrated in fibroblasts. In summary, we found that the loaded 5-FU kept its effectivity after the spray drying process and that the response towards the granules varied with cell type. This is the first step towards a tissue specific DDS.
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- 2008
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6. Effect of radiographic contrast media on the spectrin/band3-network of the membrane skeleton of erythrocytes.
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Ralf-Peter Franke, Tim Scharnweber, Rosemarie Fuhrmann, Folker Wenzel, Anne Krüger, Christof Mrowietz, and Friedrich Jung
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Medicine ,Science - Abstract
The membrane of red blood cells consists of a phospholipid bilayer with embedded membrane proteins and is associated on the cytoplasmatic side with a network of proteins, the membrane skeleton. Band3 has an important role as centre of the functional complexes e.g. gas exchange complex and as element of attachment for the membrane skeleton maintaining membrane stability and flexibility. Up to now it is unclear if band3 is involved in the morphology change of red blood cells after contact with radiographic contrast media. The study revealed for the first time that Iopromide induced markedly more severe alterations of the membrane skeleton compared to Iodixanol whose effects were similar to erythrocytes suspended in autologous plasma. A remarkable clustering of band3 was found associated with an accumulation of band3 in spicules and also a sequestration of band3 to the extracellular space. This was evidently accompanied by a gross reduction of functional band3 complexes combined with a dissociation of spectrin from band3 leading to a loss of homogeneity of the spectrin network. It could be demonstrated for the first time that RCM not only induced echinocyte formation but also exocytosis of particles at least coated with band3.
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- 2014
- Full Text
- View/download PDF
7. Substrate-enzyme affinity-based surface modification strategy for endothelial cell-specific binding under shear stress
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Ralf-Peter Franke, Karl Kratz, Ramakrishnan Ganesan, Friedrich Jung, Anne Krüger-Genge, Andreas Lendlein, and Seahyoung Lee
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education.field_of_study ,Vascular smooth muscle ,Physiology ,Endothelin converting enzyme 1 ,Chemistry ,Endothelial Cells ,Substrate (chemistry) ,Hematology ,030204 cardiovascular system & hematology ,Cleavage (embryo) ,030218 nuclear medicine & medical imaging ,Endothelial stem cell ,03 medical and health sciences ,0302 clinical medicine ,Membrane ,Physiology (medical) ,Biophysics ,Humans ,Surface modification ,Stress, Mechanical ,Cardiology and Cardiovascular Medicine ,Cell adhesion ,education - Abstract
Establishing an endothelial cell (EC) monolayer on top of the blood contacting surface of grafts is considered to be a promising approach for creating a hemocompatible surface. Here we utilized the high affinity interactions between the EC plasma membrane expressed enzyme called endothelin converting enzyme-1 (ECE-1) and its corresponding substrate big Endothelin-1 (bigET-1) to engineer an EC-specific binding surface. Since enzymatic cleavage of substrates require physical interaction between the enzyme and its corresponding substrate, it was hypothesized that a surface with chemically immobilized synthetic bigET-1 will preferentially attract ECs over other types of cells found in vascular system such as vascular smooth muscle cells (VSMCs). First, the expression of ECE-1 was significantly higher in ECs, and ECs processed synthetic bigET-1 to produce ET-1 in a cell number-dependent manner. Such interaction between ECs and synthetic bigET-1 was also detectible in blood. Next, vinyl-terminated self-assembled monolayers (SAMs) were established, oxidized and activated on a glass substrate as a model to immobilize synthetic bigET-1 via amide bonds. The ECs cultured on the synthetic bigET-1-immobilized surface processed larger amount of synthetic bigET-1 to produce ET-1 compared to VSMCs (102.9±5.13 vs. 9.75±0.74 pg/ml). The number of ECs bound to the synthetic bigET-1-immobilized surface during 1 h of shearing (5dyne/cm2) was approximately 3-fold higher than that of VSMCs (46.25±12.61 vs. 15.25±3.69 cells/100×HPF). EC-specific binding of synthetic bigET-1-immobilized surface over a surface modified with collagen, a common substance for cell adhesion, was also observed. The present study demonstrated that using the substrate-enzyme affinity (SEA) of cell type-specific enzyme and its corresponding substrate can be an effective method to engineer a surface preferentially binds specific type of cells. This novel strategy might open a new route toward rapid endothelialization under dynamic conditions supporting the long-term patency of cardiovascular implants.
- Published
- 2020
8. Effect of iodinated contrast media on the oxygen tension in the renal cortico-medullary region of pigs
- Author
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Lukas Prantl, Johannes Falter, P. Lamby, A. Krüger-Genge, F. Jung, C. Mrowietz, S. Graf, Ralf-Peter Franke, and E.L. Schellenberg
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Male ,medicine.medical_specialty ,Swine ,Physiology ,Renal cortex ,Contrast Media ,030204 cardiovascular system & hematology ,Peritubular capillaries ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Triiodobenzoic Acids ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Kidney ,business.industry ,Microcirculation ,Hemodynamics ,Iopromide ,Hematology ,Blood flow ,Acute Kidney Injury ,Iodixanol ,Oxygen tension ,medicine.anatomical_structure ,Renal blood flow ,Cardiology ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
Repeated injections of iodinated contrast media (CM) can lead to a deterioration of the renal blood flow, can redistribute blood from the renal cortex to other parts of the kidney and can cause small decreases of the blood flow in cortical capillaries, a significant reduction in blood flow in peritubular capillaries and a significant reduction in blood flow in the vasa recta. Therefore, a study in pigs was designed, to show whether the repeated injection of CM boli, alone, can cause a reduction of oxygenation in the cortico-medullar renal tissue – the region with the highest oxygen demand in the kidney - of pigs. While the mean pO2-value had only decreased by 0.3 mmHg from 29.9±4.3 mmHg to 29.6±4.3 mmHg (p = 0.8799) after the tenth Iodixanol bolus, it decreased by 5.9 mmHg from 34.0±4.3 mmHg to 28.1±4.3 mmHg after the tenth Iopromide bolus (p = 0.044). This revealed a remarkable difference in the influence of these CM on the oxygen partial pressure in the kidney. Repeated applications of CM had a significant influence on the renal oxygen partial pressure. In line with earlier studies showing a redistribution of blood from the cortex to other renal areas, this study revealed that Iodixanol – in contrast to Iopromide - induced no changes in the pO2 in the cortico-medullar region which confirms that Iodixanol did not hinder the flow of blood through the renal micro-vessels. These results are in favor of a hypothesis from Brezis that a microcirculatory disorder might be the basis for the development of CI-AKI.
- Published
- 2019
9. Erythrocyte aggregation in relation to plasma proteins and lipids
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A. Krüger-Genge, Ralf-Peter Franke, G. Pindur, M. Rampling, R. Sternitzky, and F. Jung
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Biochemistry ,Chemistry ,Molecular Biology ,Applied Microbiology and Biotechnology ,Erythrocyte aggregation ,Blood proteins ,Biotechnology - Published
- 2019
10. Evaluation of Laser-Doppler-Fluxmetry for the diagnosis of microcirculatory disorders
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C. Mrowietz, Ralf-Peter Franke, Friedrich Jung, U. Wolf, Gerhard Pindur, and R. Sternitzky
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Adult ,Male ,medicine.medical_specialty ,Physiology ,Reference range ,Coronary Artery Disease ,030204 cardiovascular system & hematology ,030218 nuclear medicine & medical imaging ,Coronary artery disease ,03 medical and health sciences ,0302 clinical medicine ,Physiology (medical) ,Internal medicine ,Laser-Doppler Flowmetry ,medicine ,Humans ,In patient ,Pathological ,business.industry ,Microcirculation ,Hematology ,Middle Aged ,medicine.disease ,Reference sample ,Laser doppler fluxmetry ,Cardiology ,Skin circulation ,Female ,Cardiology and Cardiovascular Medicine ,business ,Perfusion - Abstract
BACKGROUND: The laser Doppler fluxmetry (LDF) is a non-invasive method to assess skin blood perfusion, measuring the flow of blood cells inside a tissue volume without harming the tissue. In the diagnosis of skin circulation disorders, the results of the LDF measurement are generally used in such a way that “normal” (or non-ill) or “pathological” values are achieved by comparison with a reference sample, for example of apparently healthy subjects. MATERIAL AND METHODS: In this study, the values of LDF for the diagnosis of microcirculatory disorders in patients with coronary artery disease (n = 20) or in patients with microcirculatory disorders, already diagnosed by capillary microscopy (n = 46), were examined. RESULTS: The mean values of LD amplitudes in the four frequency windows for patients with coronary artery disease were in the reference range. However, some of the patients showed reduced LD values: in eleven of the twenty patients, one or more mean LD amplitudes were below the reference range. Four of the eleven patients had pathologically decreased capillary erythrocyte velocities of v ery = 0.09–0.21 [mm/s], while the other seven patients had normal blood circulation at rest. For all patients with a proven cutaneous microcirculatory disorder, the mean LD amplitude in at least one of the frequency windows FF2 to FF4 was pathologically reduced. CONCLUSION: The Laser-Doppler fluxmetry method used in the study allows the reliable diagnosis of cutaneous microcirculatory disorders.
- Published
- 2019
11. Histological and SEM Assessment of Blood Stasis in Kidney Blood Vessels after Repeated Intra-Arterial Application of Radiographic Contrast Media
- Author
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Jung, Philipp Lamby, Alexander Minkow, Stefan Handt, Johannes Falter, Eva-Lotte Schellenberg, Stefanie Graf, Bernhard Hiebl, Silke Haerteis, Ole Gemeinhardt, Anne Krüger-Genge, Bernd Klosterhalfen, Ernst-Michael Jung, Ralf-Peter Franke, Arash Momeni, Lukas Prantl, and Friedrich
- Subjects
acute kidney injury ,nephrotoxicity ,nephropathy ,renal pathology ,iodinated contrast media ,electron microscopy ,histopathology - Abstract
Background: After application of iodinated contrast media (CM), a pronounced deterioration of the microcirculation in skin and myocardium was reported. Clinically, the repeated application of CM, especially, led to an increase of the renal resistance index (RRI). With respect to the transiency of the RRI increase, it is reasonable to assume that the deterioration of blood flow could be due to transient blood stasis caused by reversible morphologic cell alterations due to osmotic discrepancies between CM and human blood. Therefore, the hypothesis was investigated whether CM are able to induce in vivo such blood stasis and cell deformations in the renal vasculature of well-hydrated pigs. Methods: The in vivo study was performed as a prospective randomized examination to compare the effects of two different CM in 16 pigs (German Landrace). Pigs were randomized to receive either Iodixanol (n = 8), or Iopromide (n = 8). Each animal received 10 injections separated by 5-min intervals via the suprarenal aorta at a rate of 10 mL/s according to the usual procedure during a cardiac catheter examination. Finally, the kidneys were explanted and processed for histology (H & E staining and fibrin staining according to Weigert) as well as for scanning electron microscopy (SEM) with regards to morphologic correlates explaining the changes in the microcirculation. Results: In each of the predefined four categories of vascular diameters, blood stasis were found, but clearly more often after application of Iopromide than after application of Iodixanol (p < 0.001). In addition, Iopromide induced more blood stasis in all of the examined kidney regions compared to Iodixanol (p = 0.0001). There were no obstructive events in the middle cortex following the application of Iodixanol. Except for the region around a puncture channel of a placed-in catheter probe, no fibrin was detected in Weigert’s fibrin-stained samples, neither around the histologically assessed thrombi nor in vessels with blood stasis. Complementary SEM analyses revealed in a few cases only a slight generation of fibrin and thrombi and deformations, such as echinocyte and “box-like” deformations. Conclusions: According to previous in vitro studies, pathological erythrocyte deformations, such as echinocyte and box-like formation of erythrocytes, were observed also in vivo. In addition, blood stasis and/or thrombi could be detected in histological samples from explanted kidneys from young pigs after repeated in vivo administration of CM. In only a few cases, mural platelet aggregates within minimal fibrin meshes occurred only after the application of Iopromide.
- Published
- 2020
- Full Text
- View/download PDF
12. COVID-19 and the endothelium
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F. Jung, Anne Krüger-Genge, Jan-Heiner Küpper, Ralf-Peter Franke, F. Hufert, and Publica
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2019-20 coronavirus outbreak ,Pathology ,medicine.medical_specialty ,Endothelium ,Coronavirus disease 2019 (COVID-19) ,Physiology ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Pneumonia, Viral ,030204 cardiovascular system & hematology ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Betacoronavirus ,Extracellular Vesicles ,0302 clinical medicine ,Physiology (medical) ,medicine ,Short Paper ,endocytosis ,Endothelial dysfunction ,Pandemics ,Endotheliitis ,Ultrasonography ,business.industry ,SARS-CoV-2 ,Microcirculation ,COVID-19 ,Hematology ,medicine.disease ,Prognosis ,endotheliitis ,endothelial cell dysfunction ,medicine.anatomical_structure ,Cardiology and Cardiovascular Medicine ,business ,Coronavirus Infections - Abstract
There is growing evidence that COVID-19 not only affects the lungs but beyond that the endothelial system. Recent studies showed that this can lead to microcirculatory impairments and in consequence to functional disorders of all inner organs. The combination of endothelial dysfunction with a generalized inflammatory state and complement elements may together contribute to the overall pro-coagulative state described in COVID-19 patients leading to venular as well as to arteriolar occlusions.
- Published
- 2020
13. Influence of Ultrasound Microbubbles on kidney oxygen tension
- Author
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Lukas Prantl, P. Lamby, Friedrich Jung, A. Krüger-Genge, Ernst-Michael Jung, and Ralf-Peter Franke
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Physiology ,Contrast Media ,030204 cardiovascular system & hematology ,Kidney ,030218 nuclear medicine & medical imaging ,Microcirculation ,03 medical and health sciences ,0302 clinical medicine ,Physiology (medical) ,Suprarenal Aorta ,medicine ,Humans ,Ultrasonography ,Microbubbles ,Chemistry ,business.industry ,Ultrasound ,Iopromide ,Hematology ,Blood flow ,Oxygen tension ,medicine.anatomical_structure ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug ,Biomedical engineering - Abstract
Ultrasound contrast agents (USCA) allows the dynamic detection of blood flow of both the macro and microvasculature. An obvious prerequisite for USCAs is the unhindered passage of clinically relevant dose levels through the microcirculation especially of the lungue, where they have to pass capillaries with diameters of around 4 μm. While smaller microbubbles rapidly passed through the microcirculation along with the red blood cells, larger microbubbles, however, were observed to coalesce and interrupt the blood flow. Whether this might influence the tissue oxygen tension is unclear up to now.To examine this question a bolus of 2.4 ml SonoVue™ was injected into the suprarenal aorta at a flow rate of 10 ml/s (a dosage usually applied in the clinic). The pO2 in the outer medulla of the kidney was continuously measured using a flexible pO2 microcatheter. In addition, the SonoVue™ injection and its passage through the renal vasculature were documented by the CEUS technology to assess whether the microbubbles passed the kidney.The study revealed that SonoVue™ induced no changes of the mean oxygen partial pressure in the outer medulla which confirms that these microbubbles on their way through the medullar capillaries did not hinder the co-flow of blood through the renal microvessels in a big animal model with a renal morphology and function comparable to human kidneys. These results demonstrate that the CEUS diagnostic itself did not influence the system to be examined which is a most important prerequisite for any diagnostic method.
- Published
- 2017
14. Effects of Tacrolimus or Sirolimus on the adhesion of vascular wall cells: Controlled in-vitro comparison study
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Bernhard Hiebl, A. Krüger-Genge, Ralf-Peter Franke, Friedrich Jung, and Andreas Lendlein
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0301 basic medicine ,Physiology ,Myocytes, Smooth Muscle ,Cell ,030204 cardiovascular system & hematology ,Tacrolimus ,03 medical and health sciences ,0302 clinical medicine ,Physiology (medical) ,medicine ,Humans ,Doubling time ,Cell Proliferation ,Sirolimus ,Cell growth ,Chemistry ,Endothelial Cells ,Drug-Eluting Stents ,Hematology ,Molecular biology ,In vitro ,Endothelial stem cell ,surgical procedures, operative ,030104 developmental biology ,medicine.anatomical_structure ,Cell culture ,Cardiology and Cardiovascular Medicine ,Immunosuppressive Agents ,medicine.drug - Abstract
In drug eluting stents the cytostatic drugs Sirolimus or Tacrolimus are used to inhibit blood vessel restenosis by limiting the proliferation of smooth muscle cells. However, the cytostatic activity of both drugs was shown to be not cell specific and could also affect the stent endothelialisation, respectively. Currently, only limited in vitro data are available about the impact of Sirolimus and Tacrolimus on endothelial cell proliferation over a broad concentration range. To answer this question the following study was performed.Commercially obtained HUVEC were expanded with DMEM cell culture medium (GIBCO, Germany) supplemented with 5 vol% fetal calf serum on non-coated regular polystyrene-based 24-multiwell plates. For drug testings 2×104 cells/cm2 were seeded and grown for 24 h until 30-40% of the multiwell surfaces were covered and then exposed to Sirolimus (1.0×10-11 - 1.0×10-5 mol/l) or Tacrolimus (2.0×10-8 - 6.2×10-5 mol/l), both dissolved in DMSO. 12, 24 and 48 h after adding the drugs cell numbers per area were quantified by counting the cells in six wells with four fields of view per well, representing 0.6 mm2, using a confocal laser microscope.After 48 h of cell growth in the drug-free cell culture medium, the HUVEC number increased from 2.0×104 to 3.55×104 cells/cm2 (mean cell doubling time: 53.6 h, n = 6). At lower concentrations (≤2.0×10-6 mol/l) Tacrolimus reduced the number of adherent HUVEC significantly less than Sirolimus (p < 0.05). However, at higher concentrations (≥2.07×10-5 mol/l) the effect of Tacrolimus on the number of adherent endothelial cells was significantly greater than that of Sirolimus (p < 0.05). At the highest concentration applied (6.22×10-5 mol/l), Tacrolimus induced detachment of all HUVECs within 12 h after drug application. The number of adherent HUVEC decreased only slightly (about 9%) after Sirolimus application at the highest concentration (1.09×10-5 mol/l).These data show that in a non-flow model the cytostatic drug Tacrolimus reduced the number of adherent endothelial cells less than Sirolimus, as long as the drug concentration did not surpass 10-6 mol/l. At the limits of solubility, Sirolimus (1×10-5 mol/l) reduced the number of adherent endothelial cells less than Tacrolimus (6×10-5 mol/l), which induced detachment of endothelial cells.
- Published
- 2017
15. Shear resistance of endothelial cells in a pathological environment
- Author
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Friedrich Jung, Ralf-Peter Franke, R. Fuhrmann, and Anne Krüger-Genge
- Subjects
0301 basic medicine ,Physiology ,Cell ,Coronary Artery Disease ,030204 cardiovascular system & hematology ,Microfilament ,Sepsis ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,Physiology (medical) ,medicine ,Humans ,Cells, Cultured ,Chemistry ,Septic shock ,Endothelial Cells ,Hematology ,medicine.disease ,In vitro ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,Shock (circulatory) ,Endothelium, Vascular ,Stress, Mechanical ,Implant ,medicine.symptom ,Cardiology and Cardiovascular Medicine - Abstract
Background Endothelial cells (EC) in vivo are strongly influenced by changes of the milieu exterieur. Under pathological conditions EC can become activated e.g. in hypoxic areas or during sepsis. In general, the endothelialization of implant materials is evaluated in vitro under physiological conditions. Though, in patients who receive implant materials pathological conditions are often present. An open question is therefore, how ECs seeded on a body foreign substrate behave in a pathologic microenvironment. In this in vitro study a microenvironment was created mimicking the conditions present in septic patients. To simulate this situation in vitro, serum of patients with septic shock was added to the culture medium of EC cultured on glass. The samples were sheared in a cone-plate rheometer (shear rate of 6 dyn/cm2) with subsequent analysis of the morphology, the microfilament organization and the shear resistance and compared to control cultures of EC without shock serum supplementation. Aim of the study was to investigate whether this in vitro model provides information about the functionality of an EC monolayer on a body foreign surface under pathological conditions. Results Septic conditions induced severe changes of the morphology of the adherent cells: there was a strong induction of stress fibers. In addition, lots of cells or cell groups were detached visible as denuded areas in the EC monolayer. After shear stress exposure only 28.7% of EC seeded in cell medium supplemented with serum of septic patients remained adherent (control cells: 96.8%). Conclusion The study demonstrates that the microenvironment is of extreme importance for the behavior of EC and that in vivo pathologies can be simulated in vitro. This opens the possibility to evaluate new implant materials under physiological but more important also under certain pathological conditions - simulating the implant size and the disease of the host.
- Published
- 2017
16. Effect of radiographic contrast media on renal perfusion – First results
- Author
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Lukas Prantl, C. Mrowietz, S. Graf, N Platz Batista da Silva, Ralf-Peter Franke, F. Jung, E.M. Jung, P. Lamby, Johannes Falter, and L. Schellenberg
- Subjects
medicine.medical_specialty ,Radiographic contrast media ,Swine ,Physiology ,Contrast-induced nephropathy ,Contrast Media ,030204 cardiovascular system & hematology ,Kidney ,Glomerulonephritis, Membranous ,030218 nuclear medicine & medical imaging ,Nephropathy ,03 medical and health sciences ,0302 clinical medicine ,Bolus (medicine) ,Physiology (medical) ,Animals ,Humans ,Medicine ,Prospective Studies ,Renal perfusion ,Osmole ,business.industry ,Hematology ,medicine.disease ,Resistive index ,Doppler sonography ,Radiology ,Cardiology and Cardiovascular Medicine ,business ,Nuclear medicine ,Blood Flow Velocity - Abstract
BACKGROUND: Intra-arterial administration of radiographic contrast media (CM) is discussed to impair renal perfusion. The pathogenesis of contrast-induced Nephropathy (CIN) is still not clarified. OBJECTIVE: This trial was performed to prove the effects of two CM with different molecular structure on renal perfusion. METHODS: A prospective, randomized study on 16 pigs was designed to compare the outcome after application of a low-osmolar iodinated CM (770 mOsm/kg H2O-Group1) and an iso-osmolar iodinated CM (290 mOsm/kg H(2)o-Group2). Color Coded Doppler Sonography (LOGIQ E9, GE, Milwaukee, USA) was applied for measuring the Renal Resistive Index (RRI) before and after the first, fifth, and tenth bolus of CM. Statistics was performed using analysis of variance for repeated measurements with the Factor "CM". RESULTS: All flow spectra were documented free of artifacts and Peak Systolic Velocity (PSV), Enddiastolic Velocity (EDV) and RRI respectively could be calculated. Mean PSV in Group 1 led to a decrease while in Group 2 PSV showed a significant increase after CM (p = 0,042). The course of the mean EDV in both groups deferred accordingly (p = 0,033). Mean RRI over time significantly deferred in both groups (p = 0,001). It showed a biphasic course in Group 2 and a decrease over time in Group 2. CONCLUSION: While iso-osmolar CM induced an increase of PSV and EDV together with a decrease of RRI, low-osmolar CM could not show this effect or rather led to the opposite.
- Published
- 2017
17. In memory of Prof. Dr. Holger Schmid-Schönbein
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F. Jung and Ralf-Peter Franke
- Subjects
Physiology ,Physiology (medical) ,Hematology ,Cardiology and Cardiovascular Medicine - Published
- 2018
18. Imaging of coronary arteries using ionic versus non-ionic radiographic contrast media: Intraindividual comparison study
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Anne Krüger-Genge, B. Scheller, E.M. Jung, Ralf-Peter Franke, F. Jung, U. Gerk, and Publica
- Subjects
Radiographic contrast media ,Non ionic ,Physiology ,business.industry ,medicine.medical_treatment ,Ionic bonding ,Stent ,Hematology ,Coronary arteries ,medicine.anatomical_structure ,Text mining ,Physiology (medical) ,medicine ,Intraindividual comparison ,Cardiology and Cardiovascular Medicine ,business ,Biomedical engineering - Published
- 2019
19. Effect of lipopolysaccharide on the adherence of human umbilical vein endothelial cells (HUVEC) on a natural substrate
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R. Fuhrmann, Ralf-Peter Franke, Friedrich Jung, and A. Krüger-Genge
- Subjects
Lipopolysaccharides ,Lipopolysaccharide ,Physiology ,Substrate (chemistry) ,Hematology ,030204 cardiovascular system & hematology ,Umbilical vein ,In vitro ,030218 nuclear medicine & medical imaging ,Lipid A ,Andrology ,Endothelial stem cell ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,In vivo ,Physiology (medical) ,Toxicity ,Human Umbilical Vein Endothelial Cells ,Humans ,Cardiology and Cardiovascular Medicine ,Cells, Cultured - Abstract
Polymers are often contaminated with lipopolysaccharides also known as endotoxins. Even small amounts of endotoxins can have strong effects on endothelial cell function so that the endothelialisation of cardiovascular implants might be hampered. An open question is how endothelial cells seeded on a body foreign substrate respond to shear load after adding Lipid A (LPA), the domain, which is responsible for much of the toxicity of gram-negative bacteria, and whether morphological changes of endothelial cells occur. LPA supplementation to the culture medium in increasing concentrations (5, 25 and 50μg/ml) resulted in progressive reductions of the density of adherent HUVEC after shear load (p
- Published
- 2019
20. Effect of radiographic contrast media (Iodixanol, Iobitridol) on hemolysis
- Author
-
Friedrich Jung, U. Gerk, and Ralf-Peter Franke
- Subjects
Radiographic contrast media ,business.industry ,030204 cardiovascular system & hematology ,Iobitridol ,medicine.disease ,Applied Microbiology and Biotechnology ,Iodixanol ,Hemolysis ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,medicine ,Nuclear medicine ,business ,Molecular Biology ,Biotechnology ,medicine.drug - Published
- 2016
21. Acute effects of Iodixanol on renal function after intra-arterial administration in patients with end-stage kidney disease
- Author
-
Friedrich Jung, A. Krüger-Genge, U. Gerk, and Ralf-Peter Franke
- Subjects
Male ,medicine.medical_specialty ,Physiology ,medicine.medical_treatment ,Urology ,Renal function ,Contrast Media ,030204 cardiovascular system & hematology ,030218 nuclear medicine & medical imaging ,Nephropathy ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Iodinated contrast ,Physiology (medical) ,Triiodobenzoic Acids ,medicine ,Humans ,Dialysis ,Aged ,Aged, 80 and over ,Creatinine ,medicine.diagnostic_test ,business.industry ,Acute kidney injury ,Hematology ,Acute Kidney Injury ,Middle Aged ,medicine.disease ,Iodixanol ,chemistry ,Angiography ,Kidney Failure, Chronic ,Female ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
Background Contrast-induced acute kidney injury (CI-AKI), a potentially life-threatening complication of iodinated contrast media in patients with impaired renal function, has attracted increasing attention in recent years. There is overwhelming evidence that the most important pre-disposing factor for a contrast-medium induced nephropathy is the pre-existence of a renal impairment. Methods The registry was performed as a part of a quality management project in the Dresden-Friedrichstadt heart catheter laboratory. In compliance with the Declaration of Helsinki/Somerset West, 9,026 patients were included between 2010 and 2015. 100 patients of these were participants in a chronic dialysis program. All patients were dialyzed on the day before angiography. In all patients a coronary angiography, in 28 patients a stent implantation and in 12 patients a surgical reconstruction had to be performed. Prior to the intervention and one, two and three days thereafter the serum creatinine was measured. Results Up to the third day after application of the iodinated contrast medium no significant changes of the serum creatinine (baseline value: 423.3±42.6μmol/l) occurred (ANOVA for repeated measures: p = 0.507). On average, a slight decrease of the serum creatinine was found.All patients remained in their routine dialysis-program. 18 out of 100 died during the next three months after the procedure. Conclusion The study revealed that the coronary angiography using Iodixanol as iodinated contrast medium did not result in an increase of serum creatinine, which was drastically elevated in these patients before application of the iodinated contrast medium.
- Published
- 2018
22. Actin type and distribution in erythrocytes
- Author
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Jan-Heiner Küpper, Ralf-Peter Franke, A. Krüger-Genge, Friedrich Jung, Christian Lehmann, and Publica
- Subjects
0301 basic medicine ,03 medical and health sciences ,030104 developmental biology ,Distribution (number theory) ,Chemistry ,Biophysics ,Molecular Biology ,Applied Microbiology and Biotechnology ,Actin ,Biotechnology - Abstract
Erythrocytes transport oxygen from the lungs to the tissues. The excess surface area together with the elasticity of the erythrocyte cell membrane provides the flexibility needed to pass through the microvasculature where the oxygen exchange occurs. Although the architecture of the red cell and its membrane-associated cytoskeletal network is known in general, the factors that control the characteristic shape change during echinocyte formation are poorly understood. In this short report we show that in echinocytes a completely reorganized membrane cytoskeleton with a box-like structure of actin filaments prevailed indicating the importance of the actin cytoskeleton during echinocyte formation. The red blood cell membrane is an elastic shell with remarkable properties. Peripheral erythrocytes are cell remnants, since they have lost their nuclei, cytoplasmic organelles and are no longer able to synthesize proteins and to proliferate. However, they are absolutely essential for the survival of any macro organism with a blood circulation, because they transport the majority of the necessary oxygen to the cells of the body. Human erythrocytes circulate in the body for about 120 days and are normally discocytes with a biconcave shape and a diameter of ∼7.5 mm, a surface area of ∼140 mm2 and a volume of ∼100 mm3 [1]. The excess surface area of erythrocytes (allowing the flattened shape under resting conditions), together with the elasticity of their membranes, provides them with the flexibility needed to pass through very small capillaries with diameters as small as 2-3 mm [2, 3]). The erythrocyte membrane consists of a phospholipid bilayer with embedded membrane proteins and an underlying membrane cytoskeleton.
- Published
- 2018
23. Reaction of arterial endothelial cells to stent impression: In vitro study using a model of the human artery wall
- Author
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R. Fuhrmann, F. Jung, Ralf-Peter Franke, and Anne Krüger
- Subjects
Pathology ,medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Stent ,Prostacyclin ,Anatomy ,medicine.disease ,Applied Microbiology and Biotechnology ,Extracellular matrix ,Endothelial stem cell ,medicine.anatomical_structure ,medicine ,Tonicity ,Endothelial dysfunction ,Wound healing ,business ,Molecular Biology ,Biotechnology ,medicine.drug ,Artery - Abstract
Stenoses in arterial blood vessels by artherosclerotic processes can decrease the supply of downstream tissue dramatically. The implantation of stents by percutaneous coronary intervention is one method of choice to restore the physiological blood flow. In some cases in-stent re-stenoses by thrombotic events, vascular wall hyperplasia or endothelial dysfunction occur. Causes and nature underlying this processes are not fully understood. Aim of the present study was to study the re-stenotic processes after stent impress on a cellular and molecular level in vitro. Therefore, human arterial endothelial cells (HUAEC) were seeded on a model vascular wall intima consisting of extracellular matrix secreted by bovine corneal endothelial cells. Subsequently, a pre-mounted balloon-expendable tubular stent made of 316 L was impressed through the HUAEC layer leading to an impairment of the vessel wall intima. After stent removal the wound healing process, HUAEC membrane integrity, vitality, proliferation and function were assessed. Immediately after stent impress an increased level of lactate dehydrogenase (LDH) was observed indicating an impairment of the cell membrane integrity. After 24 h baseline LDH values presented again. HUAEC vitality adjacent to the stent impress induced wound was normal (investigated by inverted microscopy). The proliferation of HUAEC was the highest in the direct vicinity of the stent impress induced wound. Prostacyclin and nitric oxide decreased significantly indicating a temporary loss of cell function. These results could imply that the healing process of the endothelial cell lesion is superior to the maintenance of vascular tonicity and downregulation of platelet aggregation.
- Published
- 2015
24. Reference range and variability of Laser-Doppler-Fluxmetry
- Author
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Friedrich Jung, Ralf-Peter Franke, C. Mrowietz, Gerhard Pindur, and U. Wolf
- Subjects
Adult ,Male ,Medical diagnostic ,Physiology ,Reference range ,030204 cardiovascular system & hematology ,030207 dermatology & venereal diseases ,03 medical and health sciences ,Laser doppler flux ,Young Adult ,0302 clinical medicine ,Reference Values ,Physiology (medical) ,Laser-Doppler Flowmetry ,Medicine ,Humans ,Skin ,Skin blood flow ,business.industry ,Microcirculation ,Healthy subjects ,Reproducibility of Results ,Hematology ,Laser Doppler velocimetry ,Middle Aged ,Clinical routine ,Healthy Volunteers ,Laser doppler fluxmetry ,Female ,Cardiology and Cardiovascular Medicine ,business ,Biomedical engineering - Abstract
The Laser Doppler technique (Laser-Doppler-Fluxmetry, LDF), a noninvasive method to estimate skin blood flow (LDF), is frequently used in research and clinical routine [1]. Here, the measurements were carried out with a new Laser Doppler system, the DOP-system, which allows to measure frequency spectra in four different frequency windows according to the velocities in venules (low velocity), capillaries (low to medium velocities), and in arteries (with high and very high velocities). However, the diagnostic reliability or the effectiveness of the LDF has not yet been evaluated sufficiently, which is indispensable, where medical diagnostics and therapy controls are concerned. For a valid interpretation of LDF values of individual patients, the knowledge of the reference range and the variability of the measured parameters is required.In four successive studies the reference range (62 apparently healthy subjects), the circadian variability (8 subjects), the variability from day-to-day (6 subjects) and over one year with monthly measurements (6 subjects) were evaluated.With the knowledge of the reference range, microcirculatory disorders can now be diagnosed using the DOP method. Following a standard measurement procedure there was no dependence of the measured data on the day or season of measurement.
- Published
- 2017
25. Effect of Ioxaglate on the cutaneous microcirculation in patients with coronary artery disease: Randomized, double blind, placebo-controlled study
- Author
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Reinhardt Sternitzky, Friedrich Jung, Christof Mrowietz, Stefan G. Spitzer, Ralf-Peter Franke, and U. Gerk
- Subjects
Male ,medicine.medical_specialty ,Radiographic contrast media ,Physiology ,Ioxaglic acid ,Placebo-controlled study ,Cutaneous microcirculation ,Coronary Artery Disease ,030204 cardiovascular system & hematology ,030218 nuclear medicine & medical imaging ,Microcirculation ,Double blind ,Coronary artery disease ,03 medical and health sciences ,0302 clinical medicine ,Double-Blind Method ,Physiology (medical) ,Internal medicine ,medicine ,Ioxaglic Acid ,Humans ,Prospective Studies ,Prospective cohort study ,Aged ,business.industry ,Hematology ,Middle Aged ,medicine.disease ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
Radiographic contrast media (RCM) can initiate microcirculatory disorders. This study was performed to investigate effects of Ioxaglate on the cutaneous microcirculation. The investigation was carried out as prospective randomized double-blind comparison in parallel-group design on two groups of n = 10 patients each who had to undergo a diagnostic coronary angiography. The confirmatory parameter of the study was mean erythrocyte capillary velocity [vRBC in mm/sec]. VRBC in the ipsilateral nail-fold capillaries was recorded continuously for 3 min before and 6 min after injection of RCM or isotonic saline solution in the A. axillaris respectively, and was evaluated off-line. VRBC in nailfold capillaries was found to be decreased by Ioxaglate by 34% 150 seconds after injection, while isotonic NaCl solution immediately induced a slight increase of 14%.
- Published
- 2017
26. Effects of Radiographic Contrast Media on the Micromorphology of the Junctional Complex of Erythrocytes Visualized by Immunocytology
- Author
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Anne Krüger, Friedrich Jung, Tim Scharnweber, Ralf-Peter Franke, and Folker Wenzel
- Subjects
Life sciences ,biology ,Pathology ,medicine.medical_specialty ,Radiographic contrast media ,radiographic contrast media ,Echinocyte ,Contrast Media ,Review ,Coronary Artery Disease ,Biology ,band 3 ,Cell junction ,Catalysis ,Exocytosis ,Iodixanol ,lcsh:Chemistry ,Inorganic Chemistry ,Cell membrane ,ddc:570 ,medicine ,Animals ,Humans ,ddc:610 ,Physical and Theoretical Chemistry ,Cytoskeleton ,lcsh:QH301-705.5 ,Molecular Biology ,Band 3 ,Spectroscopy ,Actin ,Erythrocyte Membrane ,Organic Chemistry ,cytoskeleton ,General Medicine ,Immunohistochemistry ,Actins ,Computer Science Applications ,Iopromide ,medicine.anatomical_structure ,lcsh:Biology (General) ,lcsh:QD1-999 ,erythrocytes ,Biophysics ,biology.protein ,band 4.9 ,actin - Abstract
Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium--supplied by the left coronary artery--after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton.
- Published
- 2014
27. Effect of radiographic contrast media (Iodixanol, Iopromide) on hemolysis
- Author
-
U. Gerk, A. Krüger, Ralf-Peter Franke, and F. Jung
- Subjects
Male ,medicine.medical_specialty ,Erythrocytes ,Radiographic contrast media ,Physiology ,Iohexol ,Contrast Media ,Biology ,Coronary Angiography ,Hemolysis ,Hemoglobins ,chemistry.chemical_compound ,Triiodobenzoic Acids ,Physiology (medical) ,Internal medicine ,medicine ,Humans ,ddc:610 ,Cytoskeleton ,Aged ,Erythrocyte Membrane ,Iopromide ,Hematology ,Middle Aged ,Iobitridol ,medicine.disease ,Iodixanol ,Surgery ,Radiography ,Erythrocyte membrane ,Membrane ,Endocrinology ,chemistry ,Female ,Cardiology and Cardiovascular Medicine ,Glomerular Filtration Rate ,medicine.drug - Abstract
Radiographic contrast media are able to induce changes of the morphology of erythrocytes and endothelial cells. Particularly, the change of the erythrocyte morphology is associated with a decreased deformability possibly resulting from disintegration and a loss of constituents of the membrane cytoskeleton. However, it is unclear whether there is an intravascular hemolysis as a consequence of the disintegration of the erythrocyte membrane cytoskeleton which might more or less coincide with a loss of erythrocyte membrane integrity. The results of this study showed, that free hemoglobin increased from 14.2 ± 5.1 mg/dl to 17.9 ± 9.8 mg/dl after Iobitridol application (p = 0.089), while it slightly decreased from 21.5 ± 10.9 mg/dl to 19.0 ± 12.9 mg/dl after Iodixanol application (p = 0.289). The slight decrease of free hemoglobin after application of Iodixanol differed significantly compared to the increase of free hemoglobin after Iobitridol application (p < 0.05). This different reponse is thought to give evidence to the assumption that the erythrocyte membrane integrity, in deed, was compromised leading to the release of free hemoglobin as an indicator of hemolysis as well.
- Published
- 2014
28. Radiographic contrast media alterate the localization of actin/band4.9 in the membrane cytoskeleton of human erythrocytes
- Author
-
Anne Krüger, Ralf-Peter Franke, F. Jung, R. Fuhrmann, Tim Scharnweber, C. Mrowietz, and F. Wenzel
- Subjects
Erythrocytes ,Radiographic contrast media ,Physiology ,Iohexol ,Contrast Media ,Cell junction ,Exocytosis ,Cell membrane ,Physiology (medical) ,medicine ,Humans ,ddc:610 ,Cytoskeleton ,Actin ,Chemistry ,Cell Membrane ,Microfilament Proteins ,Antibodies, Monoclonal ,Hematology ,Microfilament Protein ,Actins ,Cell biology ,Red blood cell ,medicine.anatomical_structure ,Cardiology and Cardiovascular Medicine ,Fluorescein-5-isothiocyanate - Abstract
Different radiographic contrast media (RCM) were shown to induce morphological changes of blood cells (e.g. erythrocytes or thrombocytes) and endothelial cells. The echinocytic shape change of erythrocytes, particularly, affords alterations of the membrane cytoskeleton. The cytoskeleton plays a crucial role for the shape and deformability of the red blood cell. Disruption of the interaction between components of the red blood cell membrane cytoskeleton may cause a loss of structural and functional integrity of the membrane. In this study band4.9 and actin as components of the cytoskeletal junctional complex were examined in human erythrocytes after suspension in autologous plasma or in plasma RCM mixtures (30% v/v Iodixanol-320 or Iopromide-370) followed by a successive double staining with TRITC-/FITC-coupled monoclonal antibodies. After adding Iopromide-370 to the plasma in practically none of the cells the rounded conformation of the membrane cytoskeleton - as it appeared in cells suspended in autologous plasma - was found. In addition, Iopromide-370 induced thin lines and coarse knob-like structures of band4.9 at the cell periphery while most cell centers were devoid of band4.9, and a box-like arrangement of bands of band4.9. A dissociation between colours red (actin) and green (band4.9) occurred as well. In contrast, erythrocytes suspended in a plasma/Iodixanol-320 mixture showed a membrane cytoskeleton comparable to cells suspended in autologous plasma, Similar results were found with respect to the distribution of actin. This study revealed for the first time RCM-dependent differences in band4.9 activities as possible pathophysiological mechanism for the chemotoxicity of radiographic contrast media.
- Published
- 2014
29. Organotypic soft-tissue co-cultures: Morphological changes in microvascular endothelial tubes after incubation with iodinated contrast media
- Author
-
M. Khiao In, Julia Sehl, F. Jung, Ralf-Peter Franke, Roswitha Merle, Sabine Kaessmeyer, Bernhard Hiebl, and Johanna Plendl
- Subjects
0301 basic medicine ,Physiology ,Angiogenesis ,Iomeprol ,Cell Culture Techniques ,Lumen (anatomy) ,Contrast Media ,Incubation period ,Andrology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Physiology (medical) ,medicine ,Humans ,Incubation ,Chemistry ,Endothelial Cells ,Hematology ,Fibroblasts ,Iodixanol ,Coculture Techniques ,Endothelial stem cell ,030104 developmental biology ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Cardiology and Cardiovascular Medicine ,Blood vessel ,medicine.drug - Abstract
INTRODUCTION Clinical complications like thrombosis or anaphylaxis have been described to go along with the intra-venous or intra-arterial injection of iodinated contrast media (CM). It has been suggested that the administration of CM affects rheological parameters and thereby causes reduced blood velocity in microvessels. In vitro studies revealed significant buckling of endothelial cells after exposure to CM reducing the lumen of vessels. The aim of this study was to test the influence of CM on three-dimensional microvascular tubules with open lumina within an organotypic soft-tissue co-culture assay in vitro. This model, which is based on the co-culture of endothelial cells and fibroblasts, allows the analysis and quantitation of different parameters of microvascular endothelial capillary structures. MATERIAL AND METHODS Human dermal fibroblasts and human dermal microvascular endothelial cells were co-cultured for 10 days. Fibroblasts were adapted to the endothelial cell medium before co-culture and allowed to proliferate as well as produce extracellular matrix. The co-cultures were exposed to three different CM, i.e., Iomeprol (Imeron 400MCT), Iodixanol (Visipaque 320) or Iohexol (Accupaque 350) for 1.5 minutes or 5.0 minutes, respectively. For this, a mixture of CM and cell culture medium in a ratio of 30% CM by volume was prepared. After fixation in methanol/acetone, the endothelial cells were immunolabeled with the endothelial marker anti-CD31 and the tubular structures were assessed morphometrically. RESULTS In the organotypic soft-tissue co-cultures with fibroblasts, the endothelial cells developed three-dimensional capillary-like structures which expanded via sprouting branches. After incubation with the different CM, the numbers of endothelial tubes (p = 0.001) and their lengths (p = 0.003) were significantly lower after the 5 minutes incubation time, when compared to the 1.5 minutes incubation time. The tubular diameters were significantly reduced after 5 minutes (p
- Published
- 2016
30. Microcirculation in hypertensive patients
- Author
-
Gerhard Pindur, B. Leithäuser, R. Sternitzky, Ralf-Peter Franke, G. Spitzer, J.-W. Park, P. Ohlmann, Friedrich Jung, and Sebastian Wolf
- Subjects
Pathology ,medicine.medical_specialty ,Physiology ,business.industry ,Microcirculation ,Skeletal muscle ,Essential hypertension ,medicine.disease ,Oxygen tension ,medicine.anatomical_structure ,Blood pressure ,Organ Specificity ,Physiology (medical) ,Hemorheology ,Hypertension ,medicine ,Humans ,sense organs ,Complications of hypertension ,business ,Perfusion ,Intravital microscopy - Abstract
Regardless of the mechanisms that initiate the increase in blood pressure, functional and structural changes in the systemic vasculature are the final result of long-standing hypertension. These changes can occur in the macro- but also in the microvasculature. The supply of the tissues with oxygen, nutrients, and metabolites occurs almost exclusively in the microcirculation (which comprises resistance arterioles, capillaries and venules), and an adequate perfusion via the microcirculatory network is essential for the integrity of tissue and organ function. This review focuses on results from clinical studies in hypertensive patients, which have been performed in close cooperation with different clinical groups over the last three decades. Intravital microscopy was used to study skin microcirculation, microcatheters for the analysis of skeletal muscle microcirculation, the slit lamp for conjunctival microcirculation and the laser scanning ophthalmoscope for the measurement of the retinal capillary network. The first changes of the normal microcirculation can be found in about 93% of patients with essential hypertension, long before organ dysfunctions become clinically manifest. The earliest disorders were found in skin capillaries and thereafter in the retina and the skeletal muscle. In general, the disorders in the different areas were clearly correlated. While capillary rarefaction occurred mainly in the retina and the conjunctiva bulbi, in skin capillaries morphological changes were rare. A significant decrease of capillary erythrocyte velocities under resting conditions together with a marked damping of the postischemic hyperemia was found, both correlating with the duration of hypertension or WHO stage or the fundus hypertonicus stage. Also the mean oxygen tension in the skeletal muscle was correlated with the state of the disease. These data show that the microcirculatory disorders in hypertension are systemic and are hallmarks of the long-term complications of hypertension. There is now a large body of evidence that microvascular changes occur very early and may be important in their pathogenesis and progression.
- Published
- 2013
31. Laser Doppler flux measurement for the assessment of cutaneous microcirculation – critical remarks
- Author
-
Sandro Forconi, Friedrich Jung, A.M. Ehrly, R. Sternitzky, U. Franzeck, Axel R. Pries, Ralf-Peter Franke, H. Landgraf, Michael Jünger, and B. Leithäuser
- Subjects
Physics ,medicine.diagnostic_test ,Physiology ,Scattering ,business.industry ,Microcirculation ,Hematology ,Blood flow ,Laser Doppler velocimetry ,Hematocrit ,symbols.namesake ,Laser doppler flux ,Optics ,Physiology (medical) ,Laser-Doppler Flowmetry ,symbols ,medicine ,Humans ,Cardiology and Cardiovascular Medicine ,business ,Doppler effect ,Shunt (electrical) ,Skin - Abstract
Back scattered Laser Doppler (LD) signals are composed of two different individual signals. The number of the moving particles and the speed of the particles in the measured tissue volume determine the frequency shift and the band width of the Doppler signal. The dependence of the Laser Doppler flux on the number of scattering particles is highly nonlinear: at very low hematocrit and high speed the axial migration of the cells to the centre of the blood vessels is very strong, so that in these cases - because of the parabolic flow profile - the Doppler flux measurement overestimates the mean real blood flow (up to two- or three-fold). The opposite is the case when the hematocrit is very high, then the blood flow might be underestimated (due to the increased amounts of blood cells near the vessel wall). In addition, a very change in number of moving particles - as can occur during the postprandial phase or during therapy - can change the signal also at a constant cell number. Also, it must be mentioned that the LD signal possibly is not only reflected by moving blood cells in the different skin layers but also by blood cells flowing in tissues below the skin (particularly below atrophied skin areas of older patients) so that in such cases the LD Flux signal reflects not exclusively the skin blood flow. Therefore, LD flux at rest may still be within the normal range even in advanced states of disease, since the scattered light is sampled from a tissue volume which may contain also non-nutritive shunt vessels. This critical analysis of the LD signals of course shall not lead to an overall rejection of the application of laser Doppler systems. Actual progress only can, however, be obtained under the exact consideration of anatomical conditions, technical restrictions and when generalizations are avoided.
- Published
- 2013
32. Distribution of actin of the human erythrocyte membrane cytoskeleton after interaction with radiographic contrast media
- Author
-
F. Jung, F. Wenzel, R. Fuhrmann, Anne Krüger, Tim Scharnweber, Ralf-Peter Franke, and C. Mrowietz
- Subjects
Adult ,Radiographic contrast media ,Physiology ,Chemistry ,Iohexol ,Confocal ,Erythrocyte Membrane ,Echinocyte ,Contrast Media ,EPB41 ,macromolecular substances ,Hematology ,Actins ,Staining ,Cell biology ,Membrane ,Triiodobenzoic Acids ,Physiology (medical) ,Humans ,Cardiology and Cardiovascular Medicine ,Cytoskeleton ,Actin - Abstract
A type-dependent chemotoxic effect of radiographic contrast media on erythrocytes and endothelial cells was reported several times. While mechanisms of toxicity are still unclear the cellular reactions e.g. echinocyte formation in erythrocytes and the buckling of endothelial cells coincided with deterioration of capillary perfusion (in patients with coronary artery disease) and tissue oxygen tension (in the myocardium of pigs). Whether the shape changes in erythrocytes coincide with changes in the arrangement of actin, the core of the actin-spectrin cytoskeletal network and possible actor in membrane stresses and deformation is not known until now. To get specific informations actin was stained using two different staining methods (antibodies to β-actin staining oligomeric G-actin and polymeric F-actin and Phalloidin-Rhodamin staining polymeric F-actin only). In addition, an advanced version of confocal laser scanning microscopes was used enabling the display of the actin arrangement near substrate surfaces. Blood smears were produced after erythrocyte suspension in autologous plasma or in two different plasma/RCM mixtures. In this study an even homogenous distribution of fine grained globular actin in the normal human erythrocyte could be demonstrated. After suspension of erythrocytes in a plasma/Iodixanol mixture an increased number of membrane protrusions appeared densely filled with intensely stained actin similar to cells suspended in autologous plasma, however, there in less numbers. Suspension in Iopromide, in contrast, induced a complete reorganization of the cytoskeletal actin: the fine grained globular actin distribution disappeared and only few, long and thick actin filaments bundled and possibly polymerized appeared, instead, shown here for the first time.
- Published
- 2013
33. Influence of radiographic contrast media on the nitric oxide release from human arterial and venous endothelial cells on extracellular matrix
- Author
-
F. Jung, R. Fuhrmann, and Ralf-Peter Franke
- Subjects
medicine.medical_specialty ,Radiographic contrast media ,Physiology ,Iomeprol ,Contrast Media ,Absorption (skin) ,Nitric Oxide ,Iopamidol ,Nitric oxide ,chemistry.chemical_compound ,Triiodobenzoic Acids ,Physiology (medical) ,Internal medicine ,Human Umbilical Vein Endothelial Cells ,medicine ,Humans ,Incubation ,Cells, Cultured ,business.industry ,Endothelial Cells ,Arteries ,Hematology ,Iodixanol ,In vitro ,Extracellular Matrix ,Surgery ,Endocrinology ,chemistry ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
Radiographic contrast media (RCM) can vary widely in their physicochemical properties, e.g. the iodine concentration, osmolality, molecule structure, chemotoxicity, hydrophilicity, electric charge and viscosity. Besides the necessary effect of Roentgen ray absorption, which provides contrast-rich images of vessels, RCMs can have varying adverse effects. As one possible cause of microcirculatory disorders, changes in morphology and function of endothelial cells are discussed. Therefore, RCM media-induced release of nitric oxide from arterial as well as from venous endothelial cells in contact with two commercially available RCMs (Iodixanol and Iomeprol) was investigated. NO concentrations started to increase slightly in the HUVEC control cultures after 3 min incubation time, however, NO concentrations in the cultures incubated with Iomeprol 350 and Iodixanol 320 did not change over time (Iomeprol 350: p = 0.4905; Iodixanol 320: p = 0.784). On the whole, the time-dependent NO release differed for the three groups (RCM × time: p = 0.00224). This difference was due to the fact that, after incubation with the two contrast agents (Iodixanol 320: p = 0.0003; Iomeprol 350: p = 0.0168), less NO was released by the exposed HUVEC at 3 minutes and after 12 hours than by the control cells. In the control cultures of arterial endothelial cells as well as in cultures incubated with 30% v/v Iodixanol supplemented culture medium the NO release did not change. In those cultures of arterial endothelial cells supplemented with 30% v/v Iomeprol the NO release was significantly less than in control cultures and in cultures supplemented with Iodixanol (p = 0.021; p = 0.043). Inspite of a missing shear stress in our static plane vessel wall model there was a RCM-dependent difference in NO release from endothelial cells in vitro. The NO release from venous endothelial cells differed significantly from the NO release from arterial endothelial cells. While the administration of Iomeprol induced a decrease in NO release no changes occurred after Iodixanol administration.
- Published
- 2013
34. Effects of different components of the extracellular matrix on endothelialization
- Author
-
A. Krüger-Genge, Friedrich Jung, R. Fuhrmann, and Ralf-Peter Franke
- Subjects
0301 basic medicine ,Stress fiber ,food.ingredient ,Physiology ,02 engineering and technology ,Gelatin ,Extracellular matrix ,03 medical and health sciences ,food ,Laminin ,Physiology (medical) ,Monolayer ,Humans ,Cells, Cultured ,biology ,Chemistry ,Endothelial Cells ,Hematology ,021001 nanoscience & nanotechnology ,In vitro ,Extracellular Matrix ,Endothelial stem cell ,Fibronectin ,030104 developmental biology ,Biophysics ,biology.protein ,Endothelium, Vascular ,0210 nano-technology ,Cardiology and Cardiovascular Medicine - Abstract
The endothelialization of cardiovascular prostheses is known to improve their haemocompatibility. As such body-foreign materials often do not endothelialize spontaneously. A lot of in vitro studies are ongoing how endothelialization of biomaterials can be improved. In this study the influence of different components of a tissue-typical extracellular matrix (ECM) like laminin, fibronectin or gelatin on the formation of an endothelial cell monolayer and on the shear resistance of adherent cells on these substrates was studied.The study revealed that the density of human venous endothelial cells (HUVEC) monolayers differed markedly between cells grown on a natural ECM and cells grown on singularized components of an ECM (p < 0.001). Only HUVEC grown on laminin showed similar densities and a stress fiber pattern comparable to HUVEC grown on the ECM. HUVEC grown on gelatin- or fibronectin-coated coverslips were less firmly attached to the substrate; frequently individual HUVEC and even groups of cells detached.Concluding it seems that coating of implants with laminin supports the formation of shear resistant endothelial cell (EC) monolayer - superior to other ECM components.
- Published
- 2016
35. Regenerative Medicine: Reconstruction of Tracheal and Pharyngeal Mucosal Defects in Head and Neck Surgery
- Author
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R. Fuhrmann, D. Rickert, Bernhard Hiebl, Andreas Lendlein, Ralf-Peter Franke, and Friedrich Jung
- Subjects
medicine.medical_specialty ,Polymer network ,business.industry ,Mesenchymal stem cell ,medicine ,Head and neck surgery ,Anatomy ,business ,Laryngotracheal reconstruction ,Regenerative medicine ,Surgery - Published
- 2011
36. Angiogenesis and healing with non-shrinking, fast degradeable PLGA/CaP scaffolds in critical-sized defects in the rabbit femur with or without osteogenically induced mesenchymal stem cells
- Author
-
Friedrich Jung, J. Hägele, Lukas Prantl, Bernhard Hiebl, V. Jäger, Ralf-Peter Franke, E. Costa, M.M. Almeida, H. Traupe, R. Fuhrmann, Stefan Endres, Ernst-Michael Jung, Axel Wilke, Christian Beltzer, and Catarina Santos
- Subjects
Calcium Phosphates ,Scaffold ,Materials science ,Physiology ,Mesenchymal Stem Cell Transplantation ,Bone tissue ,Bone remodeling ,Random Allocation ,chemistry.chemical_compound ,Polylactic Acid-Polyglycolic Acid Copolymer ,Tissue engineering ,Physiology (medical) ,medicine ,Animals ,Femur ,Lactic Acid ,Wound Healing ,Tissue Engineering ,Mesenchymal Stem Cells ,Prostheses and Implants ,Hematology ,Anatomy ,PLGA ,medicine.anatomical_structure ,chemistry ,Female ,Bone Remodeling ,Rabbits ,Bone marrow ,Cardiology and Cardiovascular Medicine ,Wound healing ,Polyglycolic Acid ,Biomedical engineering - Abstract
Cost effective and safely to apply tissue engineered constructs of big volume bone transplants for the reconstruction of critical sized defects (CSD) are still not available. Key problems with synthetic scaffold materials are shrinkage and fast degradation of the scaffolds, a lack of blood supply and nutrition in the central scaffold volume and the absent or the scarce development of bone tissue along the scaffold to bridge the bone defect. The use of composite scaffolds made of biopolymers like polylactidglycolid acid (PLGA) coated and loaded with calcium phosphates (CaP) revealed promising therapeutical options for the regeneration of critical sized bone defects. In this study interconnectively macroporous PLGA scaffolds loaded with microporous and coated with nanoporous calcium phosphates were either seeded in fixed bed bioreactors with allogenic osteogenically induced mesenchymal stem cells and implanted or implanted unseeded into critical sized femoral bone defects. As CSD a 12 mm long segment of the chinchilla femur was excised where the proximal and distal parts of the femur were fixed and stabilized by the use of an eight-hole linear reconstruction plate and secured with three bicortical screws (2.7 mm diameter) on every side of the osteotomy. Aim of the study was if we could find a way to load and coat PLGA scaffolds with CaP so that shrinkage of scaffolds could be avoided, which would favour angiogenesis, blood supply and nutrition in the construct and thus avoid central necroses regularly observed so far in transplants not vascularized and which would be inhabited by cells of he bone lineage forming new bone and healing the defect. Four weeks, at least, a notable shrinkage of the scaffolds was avoided and scaffolds were practically not degraded. Both scaffolds, loaded and loaded and coated, revealed blood vessels in all parts of the implants after 4 weeks. Only in scaffolds seeded with allogenic mesenchymal stem cells the development of bridging bone constructs between proximal and distal edges of the femur was observed after four weeks without further supplementation of growth factors. In case of the implantation of non-seeded scaffolds no obvious scaffold bound bone development could be shown.
- Published
- 2011
37. Influence of radiographic contrast media (Iodixanol und Iomeprol) on the morphology of human arterial and venous endothelial cells on extracellular matrix in vitro
- Author
-
Bernhard Hiebl, Friedrich Jung, R. Fuhrmann, and Ralf-Peter Franke
- Subjects
Umbilical Veins ,Pathology ,medicine.medical_specialty ,Radiographic contrast media ,Endothelium ,Physiology ,Blood viscosity ,Iomeprol ,Contrast Media ,Cell Communication ,Umbilical Arteries ,Microcirculation ,chemistry.chemical_compound ,Triiodobenzoic Acids ,Physiology (medical) ,medicine ,Humans ,Infusions, Intra-Arterial ,Cell Size ,Chemistry ,Endothelial Cells ,Hematology ,Anatomy ,Actins ,Iopamidol ,Oxygen tension ,Radiography ,Endothelial stem cell ,medicine.anatomical_structure ,Hemorheology ,Endothelium, Vascular ,Cardiology and Cardiovascular Medicine - Abstract
After intra-arterial administration of radiographic contrast media (RCM), a disorder of the downstream microcirculation both with regard to blood flow velocity in microvessels and to tissue oxygen partial pressure was described. Possible factors contributing to this microcirculatory disorder are increase in plasma viscosity, a formation of echinocytes, a buckling and denudation of endothelial cells, and a disturbation of endothelial prostacyclin release. It is not known so far whether the reactions observed in the context of RCM applications are reactions of venous endothelial cells alone or also of arterial endothelial cells. Therefore, arterial ECs on ECM were exposed to the same RCMs under identical conditions. The decrease of cell-cell contacts with an increase of denuded subendothelial matrix areas in the functionally confluent endothelial cell layer on ECM were more pronounced after a five minute exposure of endothelial cells to Iomeprol compared to Iodixanol. Changes in arterial ECs after the incubation in culture media supplemented with RCM were very subtle in comparison to changes in venous ECs.
- Published
- 2011
38. Reduced diagnostic value of lactate dehydrogenase (LDH) in the presence of radiographic contrast media
- Author
-
R. Fuhrmann, D. Rickert, Christof Mrowietz, Ralf-Peter Franke, Friedrich Jung, and Bernhard Hiebl
- Subjects
Necrosis ,Radiographic contrast media ,Physiology ,Contrast Media ,Biology ,Andrology ,chemistry.chemical_compound ,Physiology (medical) ,Lactate dehydrogenase ,medicine ,Humans ,Cell damage ,Cells, Cultured ,Cell Death ,L-Lactate Dehydrogenase ,Iopromide ,Hematology ,medicine.disease ,Iodixanol ,Radiography ,chemistry ,Biochemistry ,Apoptosis ,Cell culture ,Endothelium, Vascular ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,medicine.drug - Abstract
Isoforms of the enzyme lactate dehydrogenase (LDH) were found in almost all cells of the organism and an elevated activity of LDH in the circulation is thought to be a clear indicator of elevated cell destruction coinciding with an increased release of components from the cellular cytoplasm, e.g. LDH. Here, we report on an in-vitro examination to test whether radiographic contrast media (RCM) could induce cell destruction followed by an increase in LDH release. The RCM were tested in non-flow cultures of human umbilical venous endothelial cells (HUVEC) of the fourth passage seeded on extracellular matrix and the results were compared to those from control cultures not exposed to contrast media. The examination revealed that the addition of contrast media to the cell culture media supplemented with pooled human serum (HSP) as source of exogenous LDH was followed by a strong decrease in LDH activity both in the absence and presence of HUVEC. Within 1.5 min after the addition of contrast media to the culture medium supplemented with HSP (30% vol of the culture medium were replaced by either of two contrast media, Iodixanol or Iopromide) the LDH activity decreased about 80% compared to the initial values. In contrast, the LDH activity did not change in cell culture media not supplemented with RCM. The partial replacement of HSP supplemented cell culture medium by RCM will cause a dilution of cell culture medium constituents. The decrease of LDH activity, however, was much stronger than the decrease thought to be attributable to the effects of dilution of cell culture medium, so that the role of dilution seems to be a minor one in this case. It has to be assumed that the RCM could interact with the LDH available in the culture medium as well as with the substrates delivered with the measurement system for the assessment of LDH activity, so that both, the amount of LDH and the activities of enzymes involved might be influenced. In the presence of HUVEC a similar effect was observed. Here, a little less strong decrease of LDH activity occurred compared to the decrease in cell culture medium without HUVEC. This was unexpected because a considerable amount of HUVEC were detached after the addition of contrast media and many of these cells were damaged seriously so that a significant amount of endogenous LDH should have been released. These unexpected results make it necessary to re-evaluate those past time examinations focussed on cell damage/destruction in the presence of contrast media, where the measurement of LDH activity was used as indicator or cell vitality and where cell decease rates were correlated to questionable toxic influences. According to the results of the examination reported here it is difficult to uphold the interpretation of recently published findings that contrast media almost exclusively induce cellular apoptosis and not necrosis.
- Published
- 2010
39. Embedding of radiographic media molecules in the membrane of erythrocytes
- Author
-
Alexander Minkow, Christof Mrowietz, Ralf-Peter Franke, Bernhard Hiebl, Friedrich Jung, and R. Fuhrmann
- Subjects
Pathology ,medicine.medical_specialty ,Radiographic contrast media ,Physiology ,Scanning electron microscope ,Chemistry ,Iohexol ,Bilayer ,Erythrocyte Membrane ,Echinocyte ,Contrast Media ,Hematology ,In vitro ,Radiography ,Cell membrane ,Apposition ,medicine.anatomical_structure ,Membrane ,Triiodobenzoic Acids ,Physiology (medical) ,Microscopy, Electron, Scanning ,medicine ,Biophysics ,Humans ,Cardiology and Cardiovascular Medicine - Abstract
The incubation of erythrocytes (RBC) or endothelial cells (HUVEC) in radiographic contrast media (RCM) could induce morphological alterations of or at the cell membranes, e.g. the generation of echinocytes or the formation of stress fibres coinciding with a massive buckling of HUVEC into the vascular lumen, as was demonstrated in several examinations in the recent years. The apposition or embedding of RCM at or in the cell membranes was discussed as possible causative mechanisms because the embedding of molecules into the internal leaflet of the cell membrane bilayer is expected to bulge the cell membrane to the outside, thus inducing e.g. the generation of echinocytes. The examination presented here is based therefore on high resolution scanning electron microscopy (SEM) analyses if iodine as marker element of RCM molecules can be found near the inside of or in RBC membranes (co-localisation study). Morphological analyses exploited secondary electron images (SE) while the analysis of elements exploited either back scattered electrons (BSE) or energy dispersive X-ray analysis (EDX) or the areal display of elements in high lateral resolution in the Bit-map modus. Even at the highest convenient magnification (1:40,000) it was impossible to detect RBC membrane associated iodine (I) after RBC incubation in RCM (Iodixanol, Iopromide) in vitro. Neither in the birds view on the samples nor looking from the side on the freeze fractured samples carrying the RBC was it possible to detect either the signal cohorts typical of I in the sum spectra or the main Lα1-peak in trace analysis.
- Published
- 2010
40. Korrelation physikochemischer Oberflächeneigenschaften verschiedener Kunststoffgranulate mit ihrer Hämokompatibilität
- Author
-
Ralf-Peter Franke, M Frant, Friedrich Jung, and K Liefeith
- Subjects
Materials science ,Chemical engineering ,Platelet adhesiveness ,Biomedical Engineering - Published
- 2009
41. Extreme reduction of the capillary lumen in segments of the venular legs of human cutaneous capillaries
- Author
-
Ralf-Peter Franke and Friedrich Jung
- Subjects
Adult ,Male ,Time Factors ,medicine.medical_treatment ,Neovascularization, Physiologic ,Capillary endothelial cells ,Biochemistry ,Microcirculation ,Venules ,Precapillary sphincter ,Capillary lumen ,medicine ,Humans ,Longitudinal Studies ,Reduction (orthopedic surgery) ,Skin ,Microscopy, Video ,business.industry ,Healthy subjects ,Cell Biology ,Anatomy ,Capillaries ,Regional Blood Flow ,Endothelium, Vascular ,Cardiology and Cardiovascular Medicine ,business ,Perfusion ,Intravital microscopy - Abstract
While structure and function of precapillary sphincter cells were assured in skin capillaries it is unclear whether segmental reduction of capillary lumina can occur in human capillaries. It has been shown that endothelial cells are able to exert dynamical reactions. Since the first description of the vascular endothelium a great variety of findings were described concerning the active role of capillary endothelial cells in regulation of the capillary lumen applying intravital microscopy. The intravital microscopy was performed in the framework of an observational study to document the long-term stability of capillaries in healthy subjects over many years. In the second year one of the participants showed remarkable changes in capillaries compared to recent recordings. Control recordings were performed 1, 3, 4, 5 and 20 h after the initial examination — until a complete normalization of the capillaries occurred. This case report is documenting for the first time clearly that extreme luminal narrowing of long segments of cutaneous capillaries can also appear in humans, in this case restricted exclusively to the venular leg of the capillaries. Different from the reductions of the capillary lumen induced by electrical irritation in frogs which lasted only for seconds, the capillary lumen narrowing in this case lasted considerably longer, almost over a whole day. It is important to note that the demonstrated findings did not occur in all capillaries and it remains unclear whether such findings are restricted to skin capillaries or might occur also in other regions of the body or even systemically. It could be demonstrated clearly, however, that segmental narrowing of capillary lumina can occur in humans possibly leading to a temporary stillstand of perfusion.
- Published
- 2009
42. Calcium phosphate granules for use as a 5-Fluorouracil delivery system
- Author
-
Manuel A. Martins, Catarina Santos, Ralf-Peter Franke, M.M. Almeida, and Maria Elisabete Costa
- Subjects
Materials science ,Process Chemistry and Technology ,Mineralogy ,Nanoparticle ,Phosphate ,Controlled release ,Apatite ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Specific surface area ,visual_art ,Spray drying ,Drug delivery ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Porosity - Abstract
The possibility of tailoring apatite granules as a controlled release system for the drug model 5-Fluorouracil (5FU) has been examined. Apatite granules (SDG) were obtained by spray drying suspensions of hydroxyapatite (HAP) nanoparticles previously precipitated from citrate solutions [M.A. Martins, C. Santos, M.E.V. Costa, M.M. Almeida, Preparation of porous hydroxyapatite particles to be used as drug delivery systems, Advanced Materials Forum II (455) (2004) 353–357]. SDG had donut shape and very high specific surface area (150 m2/g) indicative of high porosity. SDG were poorly crystalline HAP but turned into biphasic granules (HSDG) with crystalline tricalcium phosphate and HAP after annealing at 800 °C, while reducing their surface area down to ∼6 m2/g. SDG and HSDG were soaked in a 5FU solution at pH 5.2 and room temperature during several days and then transferred to a phosphate buffered solution (PBS) at pH 7.4 and 37 °C, for releasing 5FU. The comparison between the 5FU adsorbing and releasing behaviours exhibited by SDG and HSDG shows that engineering the granules characteristics, i.e. specific surface area, surface chemical composition, porosity and crystal phase composition allows the 5FU release profile to be controlled.
- Published
- 2009
43. Spray-dried hydroxyapatite-5-Fluorouracil granules as a chemotherapeutic delivery system
- Author
-
Catarina Santos, Maria Elisabete Costa, M.M. Almeida, Ralf-Peter Franke, and C.F. Rovath
- Subjects
Spray dried ,Materials science ,Process Chemistry and Technology ,Nanoparticle ,Phosphate ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,stomatognathic system ,Chemical engineering ,chemistry ,Spray drying ,Drug delivery ,Materials Chemistry ,Ceramics and Composites ,Delivery system ,Bone regeneration - Abstract
This study describes the preparation and characterization of hydroxyapatite-5-Fluorouracil (5FU) granules, which are intended to be used as chemotherapeutic delivery matrices and bone regeneration templates. Suspensions of hydroxyapatite (Hap) nanoparticles in 5FU solution are spray dried as micro sized granules having donut type shape. Several spray drying temperatures are studied 80 °C being the optimized condition for obtaining granules composed by Hap and 5FU without secondary phases. The produced granules at 80 °C reveal a fast releasing rate of 5FU when soaked in buffer phosphate solution maintained at physiological temperature (37 °C), thereby indicating the potential application of the produced Hap matrices for drug delivery systems (DDSs).
- Published
- 2009
44. Intravital microscopy of the capillary perfusion in the corium limbi of the third toe of the minipig
- Author
-
Bernhard Hiebl, Johanna Plendl, Friedrich Jung, Ralf-Peter Franke, S. Braune, and Christof Mrowietz
- Subjects
Hoof and Claw ,Materials science ,Microscope ,Swine ,Physiology ,Capillary action ,Video camera ,Corium ,Tortuosity ,law.invention ,Microcirculation ,Capillary Permeability ,law ,Frame grabber ,Physiology (medical) ,Animals ,Microscopy, Video ,Hematology ,Anatomy ,Capillaries ,Perfusion ,Swine, Miniature ,Cardiology and Cardiovascular Medicine ,Intravital microscopy ,Biomedical engineering - Abstract
Several methods are available today for the investigation of microcirculation in animal models, but they can be invasive and time-consuming depending on the area investigated. In particular, non-invasive methods that can be conducted rapidly and without dye or tracer injections are in demand. The cutaneous microcirculation can be easily studied in the dorsal corium limbi of the third toe of the porcine forelimb using intravital microscopy - analogous to nail fold capillary microscopy in humans. The capillary microscopy system consists of a reflected-light microscope with a cold light source, green and infrared filters and a video camera. The video sequences were recorded using the image capture system Framegrabber (Imagenation PXC-200) and a PC (with an Intel Core 2 Duo processor, 1024 MB RAM, 160 GB hard disk, Windows XP Pro), and stored via a DVD recorder (Panasonic LQ-MD800). Quantification of capillary erythrocyte flow velocities was performed using the computer-assisted image analysis system Cap Image Version 8.5 which includes a movie tool as a video sequence storage medium. The method allows estimation of capillary density and tortuosity as well as capillary circulation in the anesthetized pig within a few minutes. First measurements were made after anesthesia induction followed by further measurements during anesthesia maintenance (3 minutes each). No differences in capillary circulation were found. The present method is thus very well suited for long-term microcirculation measurements in pigs, e.g., to evaluate therapeutic interventions in the ischemic limb model.
- Published
- 2009
45. Influence of Spray-dried Hydroxyapatite-5-Fluorouracil Granules on Cell Lines Derived from Tissues of Mesenchymal Origin
- Author
-
M.M. Almeida, Maria Elisabete Costa, Catarina Santos, Tim Scharnweber, and Ralf-Peter Franke
- Subjects
Cell type ,Antimetabolites, Antineoplastic ,5-Fluorouracil ,Drug delivery system ,Pharmaceutical Science ,in Vitro cytotoxicity ,Article ,Analytical Chemistry ,Hydroxyapatite ,Cell Line ,lcsh:QD241-441 ,Mesoderm ,Mice ,lcsh:Organic chemistry ,Spray dried particles ,Cell Line, Tumor ,Drug Discovery ,medicine ,Animals ,Cell Lineage ,Physical and Theoretical Chemistry ,Cell Proliferation ,Osteosarcoma ,Dose-Response Relationship, Drug ,Cell growth ,Chemistry ,Organic Chemistry ,Mesenchymal stem cell ,Fibroblasts ,medicine.disease ,In vitro ,Microspheres ,Rats ,Durapatite ,Chemistry (miscellaneous) ,Cell culture ,Spray drying ,Immunology ,Drug delivery ,Biophysics ,Microscopy, Electron, Scanning ,Molecular Medicine ,Fluorouracil - Abstract
In our previous work we described the preparation and characterization of spray dried hydroxyapatite micro granules loaded with 5-fluorouracil (5-FU). These loaded particles are used as a model drug delivery system (DDS). In this study we examined the in vitro response of two cell lines derived from different tissues to 5-FU loaded granules (LG). Both cell lines, either L929 cells of a mouse fibroblast lineage or cells originating from a rat osteosarcoma (ROS 17/2.8) showed a dose dependent decrease in cell proliferation in response to 5-FU-, either dissolved in the culture medium or loaded onto particles. The response of the two cell lines to loaded and nonloaded particles was different. The effect of LG and of a corresponding concentration of free 5-FU was practically the same for the ROS 17/2.8 cells indicating that ROS 17/2.8 cells were not affected by the carrier material. In contrast, L929 cells showed a slight decrease in cell proliferation also in the presence of granules not loaded with 5-FU. This is thought to be attributed to the inhibition of mitogenesis by phosphocitrates, already demonstrated in fibroblasts. In summary, we found that the loaded 5-FU kept its effectivity after the spray drying process and that the response towards the granules varied with cell type. This is the first step towards a tissue specific DDS.
- Published
- 2008
46. Nanoscale Characterization of Hydroxyapatite Particles by Electron Microscopy
- Author
-
Maria Elisabete Costa, Ralf-Peter Franke, M.M. Almeida, and Catarina Santos
- Subjects
Materials science ,law ,Nanotechnology ,Electron microscope ,Instrumentation ,Nanoscopic scale ,Characterization (materials science) ,law.invention - Abstract
Owing to its chemical similarity to the mineral phase of human bone and to its biological performance, synthetic hydroxyapatite (HA, Ca10(PO4)6(OH)2) has long been recognized as an important bone substitute material in orthopaedics, dentistry and artificial implants. HA ceramics have also been studied as drug delivery systems components where an appropriate porosity for ensuring a high ability forcarryingand delivering drugs in a controlled manner is required. For some emerging applications demanding nanoscale structured systems endowed with novel potentialities HA nanoparticles may be addressed as alternative components ensuring a large surface area for adsorbing the pharmacological substance of interest. Moreover particle porosity may offer new possibilities for drug or nutrient delivery, or for biocompatible and bioresobable structural reinforcements in osteologic implants, coatings and adhesives. Mesostructured porous calcium phosphate based systems have been synthesized at macro- and micro-scale, but well established methods for the specific synthesis of porous HA nanoparticles have not been reported so far. Yao et al. reported a successful synthesis of HA mesoporous micron-sized rods 0.5-1 μm in length and 50-100 nm in thickness but having low porosity. A new synthesis challenge for producing nano-sized particles of high surface area and having ordered mesopores is thus addressed.
- Published
- 2008
47. Influence of various radiographic contrast media on the buckling of endothelial cells
- Author
-
Friedrich Jung, Ralf-Peter Franke, R. Fuhrmann, and Bernhard Hiebl
- Subjects
Pathology ,medicine.medical_specialty ,Time Factors ,Radiographic contrast media ,Iohexol ,Echinocyte ,Iomeprol ,Contrast Media ,Biochemistry ,Andrology ,chemistry.chemical_compound ,Triiodobenzoic Acids ,medicine ,Humans ,Cell Shape ,Incubation ,Cells, Cultured ,Iopromide ,Endothelial Cells ,Cell Biology ,Iodixanol ,Iopamidol ,Endothelial stem cell ,chemistry ,Cardiology and Cardiovascular Medicine ,medicine.drug - Abstract
The intra-arterial application of radiographic contrast media (RCM) can induce decreases of blood flow velocity in downstream capillaries as well as a decrease in the tissue oxygen tension. It is unclear whether changes in endothelial cell morphology contribute to the observed microcirculatory disorders. Four RCMs (Iodixanol320, Iohexol350, Iopromide370, and Imeron350) were added to the culture medium of human umbilical venous endothelial cells (HUVEC) and used for short-term incubation studies of these cells. Addition of Iohexol ( p = 0.6377) and Iodixanol ( p = 0.6309) did not affect the HUVEC height 1.5 min after incubation in the modified cell culture media supplemented with 30% v/v of the respective RCM. Strong buckling and increased endothelial height appeared after incubation in Iopromide-supplemented medium (the cell height increased by 95% compared to cells incubated under control conditions; p = 0.0065). Addition of Iomeprol-supplemented medium caused an increase by 61.6% compared to cells incubated under control conditions; p = 0.0051. After 5 min of incubation in any of the RCM-supplemented media, there was no difference in HUVEC height in comparison to incubation in control standard culture media (each p value > 0.05). The tremendous buckling caused by Iopromide and Iomeprol, coinciding with an echinocyte formation of erythrocytes might be the reason why a bolus injection of Iopromide in vivo into the left coronary artery was followed by a 50% decrease of oxygen partial pressure in the supplied tissue.
- Published
- 2008
48. Post-Mortem Analysis of a Left Atrial Appendage Occlusion Device (PLAATO™) in a Patient with Permanent Atrial Fibrillation
- Author
-
Ralf-Peter Franke, Jai Wun Park, Ulrich Gerk, and Friedrich Jung
- Subjects
Male ,medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,P wave ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Embolization, Therapeutic ,Left atrial appendage occlusion ,Stroke ,Fatal Outcome ,Thromboembolism ,Internal medicine ,Atrial Fibrillation ,Cardiology ,Humans ,Medicine ,Atrial Appendage ,Pharmacology (medical) ,Cardiology and Cardiovascular Medicine ,business - Published
- 2008
49. Observations on the microvasculature of bone defects filled with biodegradable nanoparticulate hydroxyapatite
- Author
-
Anne Hild, Olaf Kilian, R. Fuhrmann, Ralf-Peter Franke, Sabine Wenisch, Srikanth Karnati, Eveline Baumgart-Vogt, Reinhard Schnettler, Tarja Jonuleit, and Elvira Dingeldein
- Subjects
Male ,Materials science ,Swine ,Angiogenesis ,Blotting, Western ,Biophysics ,Neovascularization, Physiologic ,Connective tissue ,Biocompatible Materials ,Bioengineering ,Osseointegration ,Biomaterials ,Implants, Experimental ,Microscopy, Electron, Transmission ,Intussusception (blood vessel growth) ,Lymphatic vessel ,medicine ,Animals ,Microscopy, Confocal ,Reverse Transcriptase Polymerase Chain Reaction ,Microcirculation ,Endothelial Cells ,Biomaterial ,Immunohistochemistry ,Endothelial stem cell ,Durapatite ,medicine.anatomical_structure ,Lymphatic system ,Microscopy, Fluorescence ,Mechanics of Materials ,Bone Substitutes ,cardiovascular system ,Ceramics and Composites ,Nanoparticles ,Bone Diseases ,Biomedical engineering - Abstract
The microvascularization of metaphyseal bone defects filled with nanoparticulate, biodegradable hydroxyapatite biomaterial with and without platelet factors enrichment was investigated in a minipig model. Results from morphological analysis and PECAM-1 immunohistochemistry showed the formation of new blood vessels into the bone defects by sprouting and intussusception of pre-existing ones. However, no significant differences were observed in the microvascularization of the different biomaterials applied (pure versus platelet factors-enriched hydroxyapatite), concerning the number of vessels and their morphological structure at day 20 after operation. The appearance of VEGFR-2 positive endothelial progenitor cells in the connective tissue between hydroxyapatite particles was also found to be independent from platelet factors enrichment of the hydroxyapatite bone substitute. In both groups formation of lymphatic vessels was detected with a podoplanin antibody. No differences were noted between HA/PLF- and HA/PLF+ implants with respect to the podoplanin expression level, the staining pattern or number of lymphatic vessels. In conclusion, the present study demonstrates different mechanisms of blood and lymphatic vessel formation in hydroxyapatite implants in minipigs.
- Published
- 2008
50. Topology‐Dependent Cellular Interactions
- Author
-
Bettina Hoffmann, Günter Ziegler, Manuela Herklotz, E. Eisenbarth, Margit Müller, Tilo Pompe, Frank Heidenau, D. Velten, Richard Funk, Joachim Rychly, J. Barbara Nebe, Carsten Werner, Frank Lüthen, Thomas K. Monsees, R. Fuhrmann, Stefan Winter, Rainer Detsch, Ralf-Peter Franke, Frank Aubertin, and Andrei P. Sommer
- Subjects
Materials science ,Interface (Java) ,Nanotechnology ,Topology ,Topology (chemistry) - Published
- 2008
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