The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
Günter Siegel - One of the best experts on this subject based on the ideXlab platform.
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Abstract 135: Complementary-Medicine Prevention of Alzheimer’s Disease by Blackcurrant Extract
Circulation-cardiovascular Quality and Outcomes, 2016Co-Authors: Günter Siegel, Felicitas Mockenhaupt, Adolf Pircher, Eugeny A. Ermilov, Stefanie HammersenAbstract:Background: Every 3.2 s, an individual falls ill with dementia, the number of persons concerned will almost be trebled by 2050, scientists communicated in London at the World Alzheimer Report 2015. They called upon government and employers to invest more in prevention. At present, 46.8 million people live with a demential disease worldwide. From a public health point of view, this high prevalence should motivate to greater efforts regarding prevention and treatment of the vascular component of the disease, because this has the potential to markedly reduce the occurrence of dementia. Methods: Flow-dependent isometric tension was measured in segments of isolated human intracerebral arteries from consciousness areas (brain surgery). Flow variations of the Krebs solution were 3, 5, 20, 40 and 100 mL/min. Krebs without and with addition of either 0.01% membrane filtered blackcurrant extract (BCE, Code 70140015, BerryPharma®) or ethanol extracted BCE was used as superfusate. Biosensor ellipsometry and EIAs were applied. VLDLapoE4/E4 (10 mg/dL) from genotypized patients and human β-amyloid Aβ42 were used in ellipsometry. Results: In controls (n = 14), brain arteries relaxed from 1.416 g (T3) to 1.011 g (T100), i.e. by 28.6% of their initial tone. Under BCE 70140015 (n = 5), vascular tone decreased from 1.390 g to 0.803 g (against control p < 0.0354). This is a 42.2% reduction in tension, a 45.2% increase in flow relaxation, and a 50.7% rise in blood perfusion. Ethanol extracted BCE, however, showed against controls an even slightly impaired relaxation (contraction by 3.6%). - BCE is bound to membrane Proteoheparan Sulfate (HS-PG), the natural flow sensor and peripheral lipoprotein receptor. Addition of VLDLapoE4/E4, Aβ42, and Ca2+ ions to HS-PG adsorbed to a silica surface led to quaternary Alzheimer plaque formation. Preincubation of HS-PG with BCE reduced VLDL docking by 5.9%, ternary plaques with Aβ42 by 11.6%, and quaternary calcified Alzheimer nanoplaques by 17.3%. Conclusion: The flow experiments show that membrane filtered BCE clearly improved endothelial function by an additional NO release, while ethanol extracted did not. This vasodilatation together with the reduction of Alzheimer nanoplaques may have a beneficial effect on cognitive functions in dementiae of the Alzheimer type, in prevention of TIA and stroke. ![][1] [1]: /embed/graphic-1.gif
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Lipoprotein Adsorption as a Biosensor Tool in Atherosclerosis
Journal of Dispersion Science and Technology, 2009Co-Authors: Martin Malmsten, Günter SiegelAbstract:Lipoprotein adsorption was investigated at a range of surfaces by in situ ellipsometry, with the aim of reaching a better understanding of its possibilities and limitations as a biosensor tool in the context of atherosclerosis. Although ellipsometry allows direct investigation of lipoprotein interfacial deposition at surfaces coated with confluent layers of endothelial cells, that is, essentially the full biological system equivalent, a simpler and more robust model system based on Proteoheparan Sulfate adsorbed via its membrane-anchoring domain at hydrophobic surfaces was found to provide largely the same information. While simplistic, it was found that Ca2+-induced adsorption of a range of lipoproteins involved in atherosclerosis at surfaces coated with Proteoheparan Sulfate indeed provides some accelerated information on initial atherosclerotic plaque formation, as evidenced by correlations between lipoprotein adsorption and well known clinical effects of lipoprotein composition and of treatment with a...
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Nanotechnologic biosensor ellipsometry and biomarker pattern analysis in the evaluation of atherosclerotic risk profile.
Biosensors & bioelectronics, 2008Co-Authors: Günter Siegel, Martin Malmsten, M. Rodríguez, Lovisa Ringstad, F. Sauer, C. Abletshauser, C. De Mey, K. Schötz, P. SchäferAbstract:A Proteoheparan Sulfate coated, hydrophobic silica surface serves as lipoprotein receptor at which the Ca(2+)-driven arteriosclerotic nanoplaque formation can be pursued by laser-based ellipsometry. Any lipoprotein from human blood can be very sensitively tested for its atherogenic properties. From the same blood sample, it is possible to determine the concentration and activity of a series of interacting biomarker molecules which, through a pattern analysis, allow to assess the state of health with respect to cardiovascular diseases. These two interlinked and complementary biosensors make a prospective cardio-cerebro-vascular risk stratification feasible, especially the sequelae of an underlying arteriosclerotic disease. Based on these diagnostic tools, an optimized therapy decision for the patient can be taken and the necessary preventive measures for the still healthy person.
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Reduction of atherosclerotic nanoplaque formation and size by Ginkgo biloba (EGb 761) in cardiovascular high-risk patients.
Atherosclerosis, 2007Co-Authors: M. Rodríguez, Martin Malmsten, Lovisa Ringstad, P. Schäfer, Sören Just, H. W. Hofer, Günter SiegelAbstract:Coating a silica surface with the isolated lipoprotein receptor Proteoheparan Sulfate (HS-PG) from arterial endothelium and vascular matrices and adding both the atherogenic VLDL/IDL/LDL lipid fraction in its native composition and Ca(2+) ions, we could observe in vitro the earliest stages of atherosclerotic plaque development by ellipsometric techniques (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients. In eight patients who had undergone an aortocoronary bypass operation, the reduction of atherosclerotic nanoplaque formation amounted to 11.9+/-2.5% (p
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Femtosecond dynamics of Proteoheparan Sulfate (HS-PG) after UV excitation—A readout for arteriosclerotic nanoplaque formation?
Biochemical and biophysical research communications, 2006Co-Authors: M. Rodríguez, Albrecht Lindinger, J. Luis Pérez Lustres, Sergey A. Kovalenko, Nikolaus P. Ernsting, Ludger Wöste, Günter SiegelAbstract:Ultrashort UV laser pulses were used to excite tryptophan residues of heparan Sulfate proteoglycan (HS-PG) in blood substitute Krebs solution. Tryptophan fluorescence is sensitive to the environment, so its shift and decay indicate the conformation and solvation state of the protein. We monitored stimulated emission and excited-state absorption by probing with delayed white-light femtosecond pulses. Comparison with bare tryptophan revealed transient absorption features which are characteristic for HS-PG. Furthermore, the effect of adding calcium salt was investigated. Differences in the spectra from solutions with and without calcium developed during several minutes, which points to changes in protein conformation, but could only be measured in the sub-ps regime. These results provide a first step to a better understanding of the molecular formation of nanoplaques in blood vessels. The goal of this work is to open a way towards biosensing of the initial stages in atherogenesis allowing for a risk assessment in cardiovascular disease.
Annette Schmidt - One of the best experts on this subject based on the ideXlab platform.
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An ellipsometry-based Alzheimer plaque mimic: Effect of β-amyloid, lipoprotein identity and apolipoprotein E isoform
Journal of colloid and interface science, 2004Co-Authors: Martin Malmsten, Annette Schmidt, Eckhart Buddecke, Ursula Kassner, Karl Winkler, Ramsey Saunders, Günter SiegelAbstract:Abstract Ca 2+ -induced deposition of low-density lipoprotein (LDL), intermediate-density lipoprotein (IDL), and high-density lipoprotein (HDL) at Proteoheparan Sulfate-modified surfaces was investigated as a function of β -amyloid (A β ) presence and apolipoprotein E isoform. Presence of β -amyloid resulted in an increased deposition, as did the E4/E4 isoform compared to the corresponding E3/E3 isoform. The results are compatible with findings reported in literature on plaque formation in Alzheimer's disease, and suggest that, although simplistic, the present model system may have some potential in biosensor studies of Alzheimer plaque formation.
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The effect of garlic on arteriosclerotic nanoplaque formation and size.
Phytomedicine : international journal of phytotherapy and phytopharmacology, 2004Co-Authors: Günter Siegel, Annette Schmidt, Eckhart Buddecke, F. Michel, Michael Ploch, M. Malmsten, Jens Pietzsch, W. SchneiderAbstract:Summary Objective : In an in vitro biosensor model (PCT/EP 97/05212), the interplay between different lipoproteins in arteriosclerotic nanoplaque formation, as well as aqueous garlic extract (0.2–5.0 g/l from LI 111 powder) as a possible candidate drug against arterio/atherosclerosis were tested within the frame of a high throughput screening. Methods : The processes described below were studied by ellipsometric techniques quantifying the adsorbed amount (nanoplaque formation) and layer thickness (nanoplaque size). A thorough description of the experimental setup has been given previously. Results : Proteoheparan Sulfate (HS-PG) adsorption to hydrophobic silica was monoexponential and after approximately 30 min constant. The addition of 2.52 mmol/l Ca 2+ led to a further increase in HS-PG adsorption because Ca 2+ was bound to the polyanionic glycosaminoglycan (GAG) chains thus screening their negative fixed charges and turning the whole molecule more hydrophobic. Incubation with 0.2 g/l aqueous garlic extract (GE) for 30 min did not change the adsorption of HS-PG. However, the following addition of Ca 2+ ions reduced the increase in adsorption by 50.8% within 40 min. The adsorption of a second Ca 2+ step to 10.08 mmol/l was reduced by even 82.1% within the next 40 min. Having detected this inhibition of receptor calcification, it could be expected that the build-up of the ternary nanoplaque complex is also affected by garlic. The LDL plasma fraction (100 mg/dl) from a healthy probationer showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca 2+ concentration, with a strong increase at higher Ca 2+ concentrations. GE, preferably in a concentration of 1 g/l, applied acutely in the experiment, markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca 2+ concentrations used. In a normal blood Ca 2+ concentration of 2.52 mmol/l, the garlic induced reduction of nanoplaque formation and molecular size amounted to 14.8% and 3.9%, respectively, as compared to the controls. Furthermore, after ternary complex build-up, GE similar to HDL, was able to reduce nanoplaque formation and size. The incubation time for HDL and garlic was only 30 min each in these experiments. Nevertheless, after this short time the deposition of the ternary complex decreased by 6.2% resp. 16.5%, i.e. the complex aggregates were basically resolvable. Conclusions : These experiments clearly proved that garlic extract strongly inhibits Ca 2+ binding to HS-PG. In consequence, the formation of the ternary HS-PG/LDL/Ca 2+ complex, initially responsible for the ‘nanoplaque’ composition and ultimately for the arteriosclerotic plaque generation, is decisively blunted.
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Reduction of arteriosclerotic nanoplaque formation and size by fluvastatin in a receptor-based biosensor model.
Cardiovascular research, 2003Co-Authors: Günter Siegel, Annette Schmidt, Martin Malmsten, C. Abletshauser, Karl WinklerAbstract:Proteoheparan Sulfate can be adsorbed onto a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, thereby representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques suggesting that HDL has a high binding affinity and a protective effect on interfacial heparan Sulfate proteoglycan layers with respect to LDL and Ca(2+) complexation. LDL was found to be deposited strongly at the Proteoheparan Sulfate-coated surface, particularly in the presence of Ca(2+), apparently through complex formation 'proteoglycan-low density lipoprotein-calcium'. This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. In a receptor-based biosensor application, this system was tested on its reliability to unveil possible acute pleiotropic effects of the lipid lowering drug fluvastatin. The VLDL/IDL/LDL and VLDL/IDL/LDL/HDL plasma fractions from a high risk patient with dyslipoproteinaemia and type 2 diabetes mellitus showed the start of arteriosclerotic nanoplaque formation at a normal blood Ca(2+) concentration, with a strong increase at higher Ca(2+) concentrations. Nanoplaque formation and size of the HDL-containing lipid fraction remained well below that of the LDL-containing lipid fraction. Fluvastatin, whether applied acutely to the patient (one single 80 mg slow release matrix tablet) or in a 2-month medication regimen, markedly slowed down this process of ternary aggregational nanoplaque build-up and substantially inhibited nanoplaque size development at all Ca(2+) concentrations used. The acute action gave no significant change in lipid concentrations of the patient. Furthermore, after nanoplaque generation, fluvastatin, similar to HDL, was able to reduce nanoplaque formation and size. These immediate effects of fluvastatin have to be taken into consideration when interpreting the clinical outcome of long-term studies.
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Differentiation of coronary smooth muscle cells to a cell cycle-arrested hypertrophic growth status by a synthetic non-toxic heparin-mimicking compound.
Atherosclerosis, 1999Co-Authors: Annette Schmidt, Wolfgang Völker, Israel Vlodavsky, Eckhart BuddeckeAbstract:Abstract Studies on the mode of action of basic fibroblast growth factor (bFGF) identified an essential role of heparan Sulfate and heparin-like molecules in the formation of distinct bFGF-heparan Sulfate–bFGF-receptor complexes that are required for bFGF-induced signal transduction. In coronary smooth muscle cells that express 6–8 ng bFGF mg −1 cell protein, the heparan Sulfate chains of membrane-associated Proteoheparan Sulfate are implicated in bFGF signaling and thus are involved in the regulation of proliferation and differentiation of vascular smooth muscle cells. We studied the mode of action of a synthetic non-Sulfated heparin-mimicking compound termed RG-13 577 (poly-4-hydroxyphenoxy acetic acid, Mr ∼5 kD) and found a dose-dependent antiproliferative effect that was characterized by a block of G 1 /S-phase transition indicated by a marked (80%) reduction of [ 3 H]thymidine incorporation at a concentration of 5 μg ml −1 RG-13 577. Cell cycle analysis showed a block of cell division in the G 1 -phase. In response to RG-13 577 the cells were converted into a hypertrophic growth status within 72 h as judged from a doubling of the cellular protein content and measurement of cell and nucleus size. The increased cell protein content resulted from a de novo synthesis and was also associated with an increase in the incorporation of [ 35 S]Sulfate into cell-associated proteoglycans, including the Proteoheparan Sulfate coreceptor of bFGF. In contrast, the compound-induced G 1 -phase arrest was associated with an extensive downregulation of the cellular and pericellular bFGF level. The reduced bFGF content was accompanied by downregulation of the bFGF signaling-involved protein kinase C-α and MAP kinase, abrogation of MAP kinase phosphorylation and overexpression of protein kinase C-γ. RG-13 577 failed to elicit apoptotic reactions at a concentration range of 0.5–10 μg ml −1 and its effect was reversible upon removal of the compound. It appears that RG-13 577 induces a phenotype transformation of coronary SMC into a metabolically active hypertrophic status that could promote repair processes after balloon angioplasty (PTCA) without stimulating cell proliferation. Development of non-toxic polyanionic compounds may provide an effective strategy to inhibit cell proliferation associated with restenosis following balloon angioplasty and coronary artery bypass surgery.
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Undersulfation of Proteoheparan Sulfate Stimulates the Expression of Basic Fibroblast Growth Factor and Protein Synthesis but Suppresses Replication of Coronary Smooth Muscle Cells
Biological chemistry, 1997Co-Authors: Christoph Schriever, G. Breithardt, Annette SchmidtAbstract:Heparan Sulfate proteoglycans are obligatory for receptor binding and mitogenic activity of the basic fibroblast growth factor (bFGF). In the present study the influence of underSulfated heparan Sulfate on the expression of basic fibroblast growth factor and coronary smooth muscle cell (cSMC) proliferation was investigated. Chlorate, known to be an inhibitor of ATP-sulfurylase, was used as a tool to suppress sulfation of heparan Sulfate. When cultured cSMC were treated with 10 mM sodium chlorate in Sulfate-depleted medium, the cell number and [3H]thymidine incorporation decreased by 76% and 66% respectively, while the protein content per cell was doubled. At the same time the [35S]Sulfate incorporation into cell-associated proteoglycans was reduced by 90%. The remaining minimal amount of available [35S]radioactivity was preferably incorporated into heparan Sulfate. Under the same conditions the [6-(3)H]glucosamine incorporation into glycosaminoglycans was not impaired. The chlorate-induced increase of cell protein content includes an overexpression of bFGF, which increased from 6-8 ng to 18-22 ng/mg cell protein. However, no changes in the distribution of bFGF between the intracellular and pericellular compartment could be observed. Cell cycle analysis by FACS revealed a G1 arrest of the cell cycle with increase of the G1/S ratio from 2.9 (control) to 6.1 (chlorate) but the DNA content per cell corresponded to normal diploid cells both in control and chlorate-treated cells. The chlorate effect can be abolished by addition of 5 mM sodium Sulfate to the cultures. Our results demonstrate an inverse association between the sulfation of heparan Sulfate and the expression of bFGF. They suggest that chlorate blocks the cell cycle in the late G1-phage and that mitogenesis of cSMC requires fully Sulfated cell-associated Proteoheparan Sulfate.
Martin Malmsten - One of the best experts on this subject based on the ideXlab platform.
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Lipoprotein Adsorption as a Biosensor Tool in Atherosclerosis
Journal of Dispersion Science and Technology, 2009Co-Authors: Martin Malmsten, Günter SiegelAbstract:Lipoprotein adsorption was investigated at a range of surfaces by in situ ellipsometry, with the aim of reaching a better understanding of its possibilities and limitations as a biosensor tool in the context of atherosclerosis. Although ellipsometry allows direct investigation of lipoprotein interfacial deposition at surfaces coated with confluent layers of endothelial cells, that is, essentially the full biological system equivalent, a simpler and more robust model system based on Proteoheparan Sulfate adsorbed via its membrane-anchoring domain at hydrophobic surfaces was found to provide largely the same information. While simplistic, it was found that Ca2+-induced adsorption of a range of lipoproteins involved in atherosclerosis at surfaces coated with Proteoheparan Sulfate indeed provides some accelerated information on initial atherosclerotic plaque formation, as evidenced by correlations between lipoprotein adsorption and well known clinical effects of lipoprotein composition and of treatment with a...
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Nanotechnologic biosensor ellipsometry and biomarker pattern analysis in the evaluation of atherosclerotic risk profile.
Biosensors & bioelectronics, 2008Co-Authors: Günter Siegel, Martin Malmsten, M. Rodríguez, Lovisa Ringstad, F. Sauer, C. Abletshauser, C. De Mey, K. Schötz, P. SchäferAbstract:A Proteoheparan Sulfate coated, hydrophobic silica surface serves as lipoprotein receptor at which the Ca(2+)-driven arteriosclerotic nanoplaque formation can be pursued by laser-based ellipsometry. Any lipoprotein from human blood can be very sensitively tested for its atherogenic properties. From the same blood sample, it is possible to determine the concentration and activity of a series of interacting biomarker molecules which, through a pattern analysis, allow to assess the state of health with respect to cardiovascular diseases. These two interlinked and complementary biosensors make a prospective cardio-cerebro-vascular risk stratification feasible, especially the sequelae of an underlying arteriosclerotic disease. Based on these diagnostic tools, an optimized therapy decision for the patient can be taken and the necessary preventive measures for the still healthy person.
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Reduction of atherosclerotic nanoplaque formation and size by Ginkgo biloba (EGb 761) in cardiovascular high-risk patients.
Atherosclerosis, 2007Co-Authors: M. Rodríguez, Martin Malmsten, Lovisa Ringstad, P. Schäfer, Sören Just, H. W. Hofer, Günter SiegelAbstract:Coating a silica surface with the isolated lipoprotein receptor Proteoheparan Sulfate (HS-PG) from arterial endothelium and vascular matrices and adding both the atherogenic VLDL/IDL/LDL lipid fraction in its native composition and Ca(2+) ions, we could observe in vitro the earliest stages of atherosclerotic plaque development by ellipsometric techniques (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients. In eight patients who had undergone an aortocoronary bypass operation, the reduction of atherosclerotic nanoplaque formation amounted to 11.9+/-2.5% (p
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Towards biosensing of arteriosclerotic nanoplaque formation using femtosecond spectroscopy.
Archives of biochemistry and biophysics, 2007Co-Authors: M. Rodríguez, Martin Malmsten, Albrecht Lindinger, Nikolaus P. Ernsting, G SiegelAbstract:The ultrafast dynamics of Proteoheparan Sulfate (HS-PG) in Krebs blood substitute solution was measured using femtosecond transient absorption spectroscopy after UV excitation. Interacting with blood lipoproteins and Ca2+ ions, the proteoglycan HS-PG is the key component of the so-called nanoplaque, the earliest stage in atherogenesis. Since tryptophan (Trp) residues are the main optically active parts of HS-PG, analogous measurements were performed on bare Trp in Krebs solution. The comparison reveals distinct differences to main characteristics of the HS-PG broadband absorption spectra. Analyzing the Trp spectra, we show that the results from transient absorption spectroscopy resemble the time constants of the chromophore ultrafast solvation dynamics that have been found by another group using fluorescence up-conversion techniques. Yet, the broadband transient absorption provides more details about the molecular dynamics, including stimulated emission, excited state absorption and resonant energy transfer. Furthermore, the absorption long time dynamics upon adding Ca2+ to the HS-PG probe were investigated by transient absorption spectroscopy and by surface force and ellipsometry investigations. Notably, a Ca2+-induced conformational change responsible for arteriosclerotic nanoplaque formation was detected. Slight differences, which are only visible as broad spectral features in the sub-picosecond time scale, provide a first insight into the molecular formation of nanoplaques in blood vessels, which may yield a better understanding of the genesis of arteriosclerosis.
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Inhibition of arteriosclerotic plaque development by garlic
Wiener Medizinische Wochenschrift, 2004Co-Authors: Günter Siegel, Frank Michel, Michael Ploch, Miguel Rodríguez, Martin MalmstenAbstract:ZIEL: In einem Biosensormodell (PCT/EP 97/05212) wurde das Wechselspiel zwischen wässrigem Knoblauchextrakt (0,2–5,0 g/l aus LI-111-Pulver) und verschiedenen Lipoproteinen auf die arteriosklerotische Nanoplaquebildung getestet, um zu prüfen, ob Knoblauch als möglicher Kandidat gegen Arterio-/Atherosklerose gelten kann. METHODIK: Die Experimente wurden mit ellipsometrischer Messtechnik durchgeführt, indem der adsorbierte Betrag (Nanoplaquebildung) und die Schichtdicke (Nanoplaquegröße) quantifiziert wurden. Eine ausführliche Beschreibung des experimentellen Designs erfolgte in früheren Publikationen. ERGEBNISSE: Die Adsorption von Proteoheparansulfat an eine hydrophobe Silikatoberfläche zeigte einen monoexponentiellen Verlauf und war nach etwa 30 min konstant. Bereits in normaler Blut-Ca^2+-Konzentration bildeten sich bei Zugabe der LDL-Plasmafraktion (100 mg/dl) eines gesunden Probanden arteriosklerotische Nanoplaques, wobei diese mit höheren Ca^2+-Konzentrationen stark zunahmen. Knoblauchextrakt, vorzugsweise in einer Konzentration von 1 g/l, verlangsamte bei akuter Applikation diesen Prozess der ternären Nanoplaquekomplexierung deutlich bei allen verwendeten Ca^2+-Konzentrationen. Bei normaler Blut-Ca^2+-Konzentration von 2,52 mmol/l betrug die Knoblauch-induzierte Verminderung der Neubildung von Nanoplaques und ihrer molekularen Größe 14,8 % bzw. 3,9 % gegenüber den Kontrollen. Nach der ternären Komplexbildung war Knoblauchextrakt, ähnlich wie HDL, in der Lage, die Nanoplaquebildung und -größe wieder zu reduzieren. Die Inkubationszeit für HDL und Knoblauch betrug in diesen Experimenten nur jeweils 30 min. Dennoch nahm nach dieser kurzen Zeit die Ablagerung des ternären Komplexes um 6,2 % bzw. 16,5 % ab, d. h., die komplexierten Aggregate waren prinzipiell wieder auflösbar. SCHLUSSFOLGERUNG: Durch diese Experimente konnte bewiesen werden, dass Knoblauchextrakt die Ca^2+-Bindung an Proteoheparansulfat stark hemmt. In der Folge wird die Bildung des ternären HS-PG/LDL/Ca^2+-Komplexes, der anfänglich für die Zusammensetzung der Nanoplaques und letztlich der arteriosklerotischen Plaqueentstehung verantwortlich ist, entscheidend eingeschränkt. OBJECTIVE: In an in vitro biosensor model (PCT/EP 97/05212), the interplay between different lipoproteins in arteriosclerotic nanoplaque formation, as well as aqueous garlic extract (0.2–5.0 g/liter from LI 111 powder) as a possible candidate drug against arterio/atherosclerosis were tested within the frame of a high-throughput screening. METHODS: The processes described below were studied by ellipsometric techniques quantifying the adsorbed amount (nanoplaque formation) and layer thickness (nanoplaque size). A thorough description of the experimental setup has been given previously. RESULTS: Proteoheparan Sulfate (HS-PG) adsorption to hydrophobic silica was monoexponential and after approximately 30 min constant. The LDL plasma fraction (100 mg/dl) from a healthy probationer showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca^2+ concentration, with a strong increase at higher Ca^2+ concentrations. Aqueous garlic extract (GE), preferably in a concentration of 1 g/liter, applied acutely in the experiment, markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca^2+ concentrations used. In a normal blood Ca^2+ concentration of 2.52 mmol/l, the garlic-induced reduction of nanoplaque formation and molecular size amounted to 14.8% and 3.9%, respectively, as compared to the controls. Furthermore, after ternary complex build-up, GE similar to HDL, was able to reduce nanoplaque formation and size. The incubation time for HDL and garlic was only 30 min each in these experiments. Nevertheless, after this short time the deposition of the ternary complex decreased by 6.2% and 16.5%, respectively, i.e., the complex aggregates were basically resolvable. CONCLUSIONS: These experiments clearly proved that garlic extract strongly inhibits Ca^2+ binding to HS-PG. In consequence, the formation of the ternary HS-PG/LDL/Ca^2+ complex, initially responsible for the nanoplaque composition and ultimately for the arteriosclerotic plaque generation, is decisively blunted.
Eckhart Buddecke - One of the best experts on this subject based on the ideXlab platform.
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An ellipsometry-based Alzheimer plaque mimic: Effect of β-amyloid, lipoprotein identity and apolipoprotein E isoform
Journal of colloid and interface science, 2004Co-Authors: Martin Malmsten, Annette Schmidt, Eckhart Buddecke, Ursula Kassner, Karl Winkler, Ramsey Saunders, Günter SiegelAbstract:Abstract Ca 2+ -induced deposition of low-density lipoprotein (LDL), intermediate-density lipoprotein (IDL), and high-density lipoprotein (HDL) at Proteoheparan Sulfate-modified surfaces was investigated as a function of β -amyloid (A β ) presence and apolipoprotein E isoform. Presence of β -amyloid resulted in an increased deposition, as did the E4/E4 isoform compared to the corresponding E3/E3 isoform. The results are compatible with findings reported in literature on plaque formation in Alzheimer's disease, and suggest that, although simplistic, the present model system may have some potential in biosensor studies of Alzheimer plaque formation.
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The effect of garlic on arteriosclerotic nanoplaque formation and size.
Phytomedicine : international journal of phytotherapy and phytopharmacology, 2004Co-Authors: Günter Siegel, Annette Schmidt, Eckhart Buddecke, F. Michel, Michael Ploch, M. Malmsten, Jens Pietzsch, W. SchneiderAbstract:Summary Objective : In an in vitro biosensor model (PCT/EP 97/05212), the interplay between different lipoproteins in arteriosclerotic nanoplaque formation, as well as aqueous garlic extract (0.2–5.0 g/l from LI 111 powder) as a possible candidate drug against arterio/atherosclerosis were tested within the frame of a high throughput screening. Methods : The processes described below were studied by ellipsometric techniques quantifying the adsorbed amount (nanoplaque formation) and layer thickness (nanoplaque size). A thorough description of the experimental setup has been given previously. Results : Proteoheparan Sulfate (HS-PG) adsorption to hydrophobic silica was monoexponential and after approximately 30 min constant. The addition of 2.52 mmol/l Ca 2+ led to a further increase in HS-PG adsorption because Ca 2+ was bound to the polyanionic glycosaminoglycan (GAG) chains thus screening their negative fixed charges and turning the whole molecule more hydrophobic. Incubation with 0.2 g/l aqueous garlic extract (GE) for 30 min did not change the adsorption of HS-PG. However, the following addition of Ca 2+ ions reduced the increase in adsorption by 50.8% within 40 min. The adsorption of a second Ca 2+ step to 10.08 mmol/l was reduced by even 82.1% within the next 40 min. Having detected this inhibition of receptor calcification, it could be expected that the build-up of the ternary nanoplaque complex is also affected by garlic. The LDL plasma fraction (100 mg/dl) from a healthy probationer showed beginning arteriosclerotic nanoplaque formation already at a normal blood Ca 2+ concentration, with a strong increase at higher Ca 2+ concentrations. GE, preferably in a concentration of 1 g/l, applied acutely in the experiment, markedly slowed down this process of ternary aggregational nanoplaque complexation at all Ca 2+ concentrations used. In a normal blood Ca 2+ concentration of 2.52 mmol/l, the garlic induced reduction of nanoplaque formation and molecular size amounted to 14.8% and 3.9%, respectively, as compared to the controls. Furthermore, after ternary complex build-up, GE similar to HDL, was able to reduce nanoplaque formation and size. The incubation time for HDL and garlic was only 30 min each in these experiments. Nevertheless, after this short time the deposition of the ternary complex decreased by 6.2% resp. 16.5%, i.e. the complex aggregates were basically resolvable. Conclusions : These experiments clearly proved that garlic extract strongly inhibits Ca 2+ binding to HS-PG. In consequence, the formation of the ternary HS-PG/LDL/Ca 2+ complex, initially responsible for the ‘nanoplaque’ composition and ultimately for the arteriosclerotic plaque generation, is decisively blunted.
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Differentiation of coronary smooth muscle cells to a cell cycle-arrested hypertrophic growth status by a synthetic non-toxic heparin-mimicking compound.
Atherosclerosis, 1999Co-Authors: Annette Schmidt, Wolfgang Völker, Israel Vlodavsky, Eckhart BuddeckeAbstract:Abstract Studies on the mode of action of basic fibroblast growth factor (bFGF) identified an essential role of heparan Sulfate and heparin-like molecules in the formation of distinct bFGF-heparan Sulfate–bFGF-receptor complexes that are required for bFGF-induced signal transduction. In coronary smooth muscle cells that express 6–8 ng bFGF mg −1 cell protein, the heparan Sulfate chains of membrane-associated Proteoheparan Sulfate are implicated in bFGF signaling and thus are involved in the regulation of proliferation and differentiation of vascular smooth muscle cells. We studied the mode of action of a synthetic non-Sulfated heparin-mimicking compound termed RG-13 577 (poly-4-hydroxyphenoxy acetic acid, Mr ∼5 kD) and found a dose-dependent antiproliferative effect that was characterized by a block of G 1 /S-phase transition indicated by a marked (80%) reduction of [ 3 H]thymidine incorporation at a concentration of 5 μg ml −1 RG-13 577. Cell cycle analysis showed a block of cell division in the G 1 -phase. In response to RG-13 577 the cells were converted into a hypertrophic growth status within 72 h as judged from a doubling of the cellular protein content and measurement of cell and nucleus size. The increased cell protein content resulted from a de novo synthesis and was also associated with an increase in the incorporation of [ 35 S]Sulfate into cell-associated proteoglycans, including the Proteoheparan Sulfate coreceptor of bFGF. In contrast, the compound-induced G 1 -phase arrest was associated with an extensive downregulation of the cellular and pericellular bFGF level. The reduced bFGF content was accompanied by downregulation of the bFGF signaling-involved protein kinase C-α and MAP kinase, abrogation of MAP kinase phosphorylation and overexpression of protein kinase C-γ. RG-13 577 failed to elicit apoptotic reactions at a concentration range of 0.5–10 μg ml −1 and its effect was reversible upon removal of the compound. It appears that RG-13 577 induces a phenotype transformation of coronary SMC into a metabolically active hypertrophic status that could promote repair processes after balloon angioplasty (PTCA) without stimulating cell proliferation. Development of non-toxic polyanionic compounds may provide an effective strategy to inhibit cell proliferation associated with restenosis following balloon angioplasty and coronary artery bypass surgery.
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Heparin-induced overexpression of basic fibroblast growth factor, basic fibroblast growth factor receptor, and cell-associated Proteoheparan Sulfate in cultured coronary smooth muscle cells.
Arteriosclerosis thrombosis and vascular biology, 1996Co-Authors: Adriane Skaletz-rorowski, Annette Schmidt, G. Breithardt, Eckhart BuddeckeAbstract:Basic fibroblast growth factor (bFGF), a potent mitogen for arterial smooth muscle cells (SMCs), plays a pivotal role in the pathogenesis of arteriosclerosis and restenosis. Heparin in nanogram quantities may promote or even be required for binding of bFGF to its cognate receptor. Conversely, heparin in microgram doses is a strong inhibitor of arterial SMC replication in vitro and in vivo. Bovine coronary SMCs (cSMCs) express bFGF, bFGF receptor (FGF-R1), and cell membrane-integrated Proteoheparan Sulfate (HSPG). These three molecules are known to form a trimolecular complex that promotes signal transduction and mitogenesis. The bFGF synthesized by cSMCs is distributed to an intracellular and a pericellular compartment. Resting cultured cells retain about 80% of their bFGF intracellularly; 20% is found in the pericellular region. During proliferation, 70% to 80% of total bFGF is expressed in the pericellular compartment. Trypsinization generates soluble forms of the complex of bFGF with the ectodomains of the bFGF receptor and cell membrane-integrated HSPG in the pericellular compartment, thus allowing quantification of pericellular bFGF by a highly specific enzyme immunoassay. Standard heparin inhibits the proliferation of cSMCs by up to 80% in a concentration range between 10 and 100 micrograms/mL medium in a dose-dependent manner but increases the protein content of cSMCs compared with proliferating control cells. The heparin-induced increase in cellular protein content includes a 60% to 100% increase in the expression of pericellular bFGF, FGF-R1, and cell membrane-integrated HSPG. Thus, under heparin treatment, the heparan Sulfate side chains of cell membrane-integrated HSPG incorporate more [35S]Sulfate, and the proportion of [35S]heparan Sulfate among total glycosaminoglycans increases from 36% to 52%. Fluorescence-activated cell sorting analysis and [3H]thymidine incorporation experiments provide evidence for multiple effects of heparin, including blocks at early and late checkpoints of the cell cycle in heparin-treated cells. These results indicate that heparin, despite its anti-proliferative potency, stimulates the expression of all components of the bFGF system even in coronary SMCs in which growth is inhibited.
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Human recombinant insulin-like growth factor I and -II stimulate the expression of basic fibroblast growth factor but suppress the division of bovine coronary smooth muscle cells.
Atherosclerosis, 1996Co-Authors: Christoph Schriever, Annette Schmidt, G. Breithardt, Eckhart BuddeckeAbstract:Abstract Insulin-like growth factor I and II (IGF-I and -II) — two 7.65- and 7.47-kDa polypeptides belonging to the somatomedine family — are regular constituents of human blood plasma. Both factors exert mitogenic activity on a variety of cell types including arterial smooth muscle cells. In the present study, the effect of IGF-I and -II on cultured bovine coronary smooth muscle cells (cSMC) was assessed. Human recombinant IGF-I and IGF-II added to cSMC cultured in a medium containing 10% fetal bovine serum (FBS) decreased the cell number and [ 3 H]thymidine incorporation in a dose dependent fashion up to 40% and 43% compared to control cells (100%). At the same time, the expression of basic fibroblast growth factor (bFGF) increased from 60 pg/5 × 10 4 cells (control) to 75 (IGF-I) and 113 pg5 x 104 cells (IGF-II). In parallel with enhanced bFGF expression, the bFGF receptor content per cell and the [ 35 S]Sulfate incorporation into extracellular and cell-associated proteoglycans also increased under the influence of IGF-I and -II. In contrast, with low serum concentration (0.1% FBS) the addition of IGF-I and -II to bovine cSMC cultures resulted in a slight increase in cell number, protein content and [ 3 H]thymidine incorporation as described in previous studies. These results suggest that the mitogenic activity of IGF-I and -II towards coronary smooth muscle cells depends on culture conditions. In the presence of 10% fetal bovine serum that mimics in vivo conditions. IGF-I and -II did not necessarily act as mitogenic factors but inhibited the proliferation of cSMC in vitro possibly by modulating and antagonizing the action of other growth factors. Irrespective of the inhibition of cell division, the cellular bFGF, the bFGF receptor and the bFGF activity-related Proteoheparan Sulfate were overexpressed under the influence of IGF.
M. Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Nanotechnologic biosensor ellipsometry and biomarker pattern analysis in the evaluation of atherosclerotic risk profile.
Biosensors & bioelectronics, 2008Co-Authors: Günter Siegel, Martin Malmsten, M. Rodríguez, Lovisa Ringstad, F. Sauer, C. Abletshauser, C. De Mey, K. Schötz, P. SchäferAbstract:A Proteoheparan Sulfate coated, hydrophobic silica surface serves as lipoprotein receptor at which the Ca(2+)-driven arteriosclerotic nanoplaque formation can be pursued by laser-based ellipsometry. Any lipoprotein from human blood can be very sensitively tested for its atherogenic properties. From the same blood sample, it is possible to determine the concentration and activity of a series of interacting biomarker molecules which, through a pattern analysis, allow to assess the state of health with respect to cardiovascular diseases. These two interlinked and complementary biosensors make a prospective cardio-cerebro-vascular risk stratification feasible, especially the sequelae of an underlying arteriosclerotic disease. Based on these diagnostic tools, an optimized therapy decision for the patient can be taken and the necessary preventive measures for the still healthy person.
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Reduction of atherosclerotic nanoplaque formation and size by Ginkgo biloba (EGb 761) in cardiovascular high-risk patients.
Atherosclerosis, 2007Co-Authors: M. Rodríguez, Martin Malmsten, Lovisa Ringstad, P. Schäfer, Sören Just, H. W. Hofer, Günter SiegelAbstract:Coating a silica surface with the isolated lipoprotein receptor Proteoheparan Sulfate (HS-PG) from arterial endothelium and vascular matrices and adding both the atherogenic VLDL/IDL/LDL lipid fraction in its native composition and Ca(2+) ions, we could observe in vitro the earliest stages of atherosclerotic plaque development by ellipsometric techniques (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients. In eight patients who had undergone an aortocoronary bypass operation, the reduction of atherosclerotic nanoplaque formation amounted to 11.9+/-2.5% (p
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Towards biosensing of arteriosclerotic nanoplaque formation using femtosecond spectroscopy.
Archives of biochemistry and biophysics, 2007Co-Authors: M. Rodríguez, Martin Malmsten, Albrecht Lindinger, Nikolaus P. Ernsting, G SiegelAbstract:The ultrafast dynamics of Proteoheparan Sulfate (HS-PG) in Krebs blood substitute solution was measured using femtosecond transient absorption spectroscopy after UV excitation. Interacting with blood lipoproteins and Ca2+ ions, the proteoglycan HS-PG is the key component of the so-called nanoplaque, the earliest stage in atherogenesis. Since tryptophan (Trp) residues are the main optically active parts of HS-PG, analogous measurements were performed on bare Trp in Krebs solution. The comparison reveals distinct differences to main characteristics of the HS-PG broadband absorption spectra. Analyzing the Trp spectra, we show that the results from transient absorption spectroscopy resemble the time constants of the chromophore ultrafast solvation dynamics that have been found by another group using fluorescence up-conversion techniques. Yet, the broadband transient absorption provides more details about the molecular dynamics, including stimulated emission, excited state absorption and resonant energy transfer. Furthermore, the absorption long time dynamics upon adding Ca2+ to the HS-PG probe were investigated by transient absorption spectroscopy and by surface force and ellipsometry investigations. Notably, a Ca2+-induced conformational change responsible for arteriosclerotic nanoplaque formation was detected. Slight differences, which are only visible as broad spectral features in the sub-picosecond time scale, provide a first insight into the molecular formation of nanoplaques in blood vessels, which may yield a better understanding of the genesis of arteriosclerosis.
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femtosecond dynamics of Proteoheparan Sulfate hs pg after uv excitation a readout for arteriosclerotic nanoplaque formation
Biochemical and Biophysical Research Communications, 2006Co-Authors: M. Rodríguez, Albrecht Lindinger, Sergey A. Kovalenko, Nikolaus P. Ernsting, Ludger Wöste, Luis Perez J Lustres, G SiegelAbstract:Ultrashort UV laser pulses were used to excite tryptophan residues of heparan Sulfate proteoglycan (HS-PG) in blood substitute Krebs solution. Tryptophan fluorescence is sensitive to the environment, so its shift and decay indicate the conformation and solvation state of the protein. We monitored stimulated emission and excited-state absorption by probing with delayed white-light femtosecond pulses. Comparison with bare tryptophan revealed transient absorption features which are characteristic for HS-PG. Furthermore, the effect of adding calcium salt was investigated. Differences in the spectra from solutions with and without calcium developed during several minutes, which points to changes in protein conformation, but could only be measured in the sub-ps regime. These results provide a first step to a better understanding of the molecular formation of nanoplaques in blood vessels. The goal of this work is to open a way towards biosensing of the initial stages in atherogenesis allowing for a risk assessment in cardiovascular disease.
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Femtosecond dynamics of Proteoheparan Sulfate (HS-PG) after UV excitation—A readout for arteriosclerotic nanoplaque formation?
Biochemical and biophysical research communications, 2006Co-Authors: M. Rodríguez, Albrecht Lindinger, J. Luis Pérez Lustres, Sergey A. Kovalenko, Nikolaus P. Ernsting, Ludger Wöste, Günter SiegelAbstract:Ultrashort UV laser pulses were used to excite tryptophan residues of heparan Sulfate proteoglycan (HS-PG) in blood substitute Krebs solution. Tryptophan fluorescence is sensitive to the environment, so its shift and decay indicate the conformation and solvation state of the protein. We monitored stimulated emission and excited-state absorption by probing with delayed white-light femtosecond pulses. Comparison with bare tryptophan revealed transient absorption features which are characteristic for HS-PG. Furthermore, the effect of adding calcium salt was investigated. Differences in the spectra from solutions with and without calcium developed during several minutes, which points to changes in protein conformation, but could only be measured in the sub-ps regime. These results provide a first step to a better understanding of the molecular formation of nanoplaques in blood vessels. The goal of this work is to open a way towards biosensing of the initial stages in atherogenesis allowing for a risk assessment in cardiovascular disease.
