Progression of native coronary plaques and in-stent restenosis are associated and predicted by increased pre-procedural C reactive protein.
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Aged↗
Biomedical subjects
A Jabs
Publications and source records attributed to A Jabs.
[Association between progression of untreated coronary lesions and in-stent restenosis].
BACKGROUND AND OBJECTIVES: Progression of coronary artery disease is only incompletely understood regarding de-novo stenoses as well as in-stent restenoses (ISR) indicative of accelerated atherosclerosis. The objective of the present angiographic study was to prove an association between target lesion ISR and progression of primarily untreated coronary lesions. PATIENTS AND METHODS: A total of 179 high-grade native coronary stenoses (mean diameter stenosis 68+/-16 %) of 131 patients were treated by stent implantation. Additional 101 lesions remained untreated because of their moderate to intermediate diameter stenoses (>30 %). Quantitative coronary angiographic analysis was performed 6+/-2 months later to evaluate ISR (diameter stenosis > 50 %), coronary progression (>20 % increase in diameter stenosis) and regression (>20 % decrease), respectively. Angiographic, procedural and clinical characteristics were assessed for a possible association with ISR and/or coronary progression and regression, respectively. RESULTS: ISR was seen in 70 of 179 (39 %) stented target lesions. Presence of diabetes mellitus (p = 0.04) and cumulative duration of inflations (p = 0.01) as procedural determinant were predictive for ISR. Significant progression was found in ten of 101 (10 %) primarily untreated lesions. Progression of previously normal segments or regression were not seen. Progression of native plaques was associated with ISR presence in nine cases and with ISR absence in only one case (p = 0.01). Of note, smoking (p = 0.02) turned out to be predictive for plaque progression, whereas medication and procedural/angiographic parameters were not. CONCLUSIONS: The findings of the present pilot study demonstrate target lesion ISR associated with progression of other primarily untreated lesions and thereby suggest that both atherosclerosis types share common systemic pathogenetic mechanisms. With presence of ISR, coronary angiography should also include primarily untreated arteries, especially in case of preexisting plaques.
Adult↗
[Neointimal hyperplasia by luminal cell recruitment and not be transmural migration. The role of Bcl-2 and HSP47 after balloon angioplasty].
Restenosis post angioplasty remains the major limitation of several therapeutic interventions including stent implantation. This explains the ongoing interest in its basic pathogenic mechanisms and factors. The aim of the present study was to assess the localization and maximal expression of Bcl-2, a central antiapoptotic protooncogene, and of heat shock protein 47 (HSP47), a marker of early collagen synthesis, in the context with hyperplastic neointima formation as well as concomitant transmural remodeling processes following angioplasty. 0, 4, 24 and 48 hours, 4, 7 and 14 days post balloon traumatization by use of a rat carotid artery model, specific vascular wall compartments were evaluated concerning area, cell density as well as Bcl-2 and HSP47 expression by immunohistochemistry and morphometry, supplemented by electron microscopy (TEM). Neointimal cell accumulation was detected 4 days post angioplasty, characterized by luminal cells adherent to the internal elastic lamina, associated with maximal Bcl-2 and HSP47 expression amounting to 49% and 41%, respectively. With ongoing neointimal formation, a luminal prevalence of both key determinants and a decreasing expression in basal neointimal areas were found. In the media, a temporally reduced cell density was observed significant at 48 hours post trauma. Constitutive HSP47 expression of the media was constant during the entire observation period, whereas sparse Bcl-2 signalling was induced post angioplasty maximal on day 2 with 3% and on day 14 with 5%. The adventitia demonstrated a transient structural separation between day 4 and 7, exhibiting an inner layer with sparse cellularity and an outer layer with extremely high cell density as well as pronounced neovascularization. In this outer adventitia layer, a high frequency of signals for both Bcl-2 and HSP47 were observed amounting to 29% and 57%, respectively. Complementary TEM analysis gave no evidence of transmural migratory events propagated by adventitial cells and thereby supports early neointimal formation by luminal cell recruitment and marked co-expression of anti-apoptotic Bcl-2 and matrix-generating HSP47 as important survival factors. Clinical implications of these findings may be seen in the integration of proapoptotic substances with temporal efficacy in order to prevent restenosis, e.g., by use of coated stents.
Angioplasty, Balloon, Coronary↗
Insights into vascular pathology after intracoronary brachytherapy.
Post-angioplasty restenosis is a major limitation of interventional cardiology. A large body of evidence reveals that expression of myofibroblast activity promoters moves progressively from the neoadventitia to the neointima. Brachytherapy inhibits vascular cell activity (proliferation, migration), mitigates recruitment of intimal cells, and shows a favorable prophylactic effect on late vascular remodeling by preventing adventitial constriction at the injured site. These effects of brachytherapy are dose related. Clinical and experimental data demonstrate that restenosis is determined by the balance between arterial remodeling and intimal hyperplasia. Apparently, brachytherapy-induced positive remodeling plays the principal role in increasing the luminal diameter after PTCA and, in case of a lower dose or dose fall-off, to cause detrimental edge effects. With regard to clinical course, healing defects, endothelial dysfunction and stent-vessel wall malapposition are apparently important and possibly underestimated features of vascular pathology, since they may contribute to late thrombosis and delayed intimal hyperplasia in long-term course after intracoronary brachytherapy.
Angioplasty, Balloon, Coronary↗
[Decreased platelet aggregation during angiotensin-converting enzyme inhibitor therapy. Results of a pilot study].
BACKGROUND AND OBJECTIVE: Plaque rupture and subsequent thrombosis are key events in the complication and progression of atherosclerotic disease. Recently, the HOPE study showed a significant decrease in cardiovascular complications with the angiotensin converting enzyme (ACE) inhibitor (ramipril). To assess the therapeutic potential of this drug class, the present study evaluates the coagulative activity in cardiovascular patients with ACE inhibitors and compares these data with those of untreated patients and with those of patients taking aspirin, resp. METHODS: Blood samples from 204 patients with coronary heart disease and/or arterial hypertension were analyzed by whole-blood lumi-aggregometry. Platelet aggregation was determined by the increase in impedance across paired electrodes in response to the stimulatory agents collagen and ADP, respectively. The data were correlated with the presence or absence of ACE inhibitor and/or aspirin medication. Analogously, the coagulative potential of beta-blockers, calcium antagonists, CSE-inhibitors and nitrates were studied. RESULTS: As the central finding, study participants treated with ACE inhibitors showed a decreased platelet aggregation compared to untreated control patients, indicated by a significantly reduced increase in impedance. Platelet aggregation induced by collagen decreased by 18% (p = 0.025), that induced by ADP by 39% (p = 0.039). With aspirin medication, the collagen-induced decrease amounted to 20% (p = 0.020); no significant effect was seen by ADP stimulation. With combined intake of ACE inhibitors and aspirin, collagen-induced platelet aggregation was found markedly reduced. Platelet aggregation decreased by 26% (p = 0.003). Beta-blockers, calcium antagonists, CSE inhibitors and nitrates did not reveal a significant influence on platelet aggregation. CONCLUSIONS: ACE inhibition decreases platelet aggregation, as detected and quantified by ex vivo whole-blood aggregometry. Beyond known effects of this drug class, in particular on endothelium and fibrinolysis, antithrombotic effects may explain the positive influence on major clinical cardiovascular events.
Aged↗
C-H...pi-interactions in proteins.
A non-redundant set of 1154 protein structures from the Protein Data Bank was examined with respect to close interactions between C-H-donor and pi-acceptor groups. A total of 31,087 interactions were found to satisfy our selection criteria. Their geometric parameters suggest that these interactions can be classified as weak hydrogen bonds.A set of 12 interaction classes were defined based on the division of the donors into three groups and the acceptors into four groups. These classes were examined separately, and the respective interactions described in detail in each class. Most prominent were interactions between aliphatic C-H donors and aromatic pi-acceptors and interactions between aromatic C-H donors and aromatic pi-acceptors. About three-quarters of the Trp-rings, half of all Phe and Tyr-rings and a quarter of all His-rings were found to be involved as acceptors in C-H...pi-interactions. On the donor side, a preference for aromatic C-H groups was observed, but also for the aliphatic side-chains of the long, extended amino acid residues Lys, Arg and Met, and the Pro ring. The average distance between the C-donor and the center-of-mass of the pi-acceptor was observed to be significantly longer in the 174 protein structures determined at >2.5 A resolution. Also, the distribution is significantly wider. This resolution dependence suggests that the force fields commonly used for the refinement of protein structures may not be adequate. C-H...pi-interactions involving aromatic groups either as donor or as acceptor groups are found mostly in the interior of the protein. The more hydrophilic the participating groups are, the closer to the surface are the interactions located. About 40 % of all C-H...pi-interactions occur between amino acid residue side-chains that are separated by nine or less residues in sequence. Dependent on the interaction class, different preferences for secondary structure, residue type and side-chain conformation were observed. It is likely that the C-H...pi-interactions contribute significantly to the overall stability of a protein.
Databases, Factual↗
Active oligomeric states of pyruvate decarboxylase and their functional characterization.
Homomeric pyruvate decarboxylase (E.C 4.1.1.1) from yeast consists of dimers and tetramers under physiological conditions, a K(d) value of 8.1 microM was determined by analytical ultracentrifugation. Dimers and monomers of the enzyme could be populated by equilibrium denaturation using urea as denaturant at defined concentrations and monitored by a combination of optical (fluorescence and circular dichroism) and hydrodynamic methods (analytical ultracentrifugation). Dimers occur after treatment with 0.5 M urea, monomers with 2.0 M urea independent of the protein concentration. The structured monomers are catalytically inactive. At even higher denaturant concentrations (6 M urea) the monomers unfold. The contact sites of two monomers in forming a dimer as the smallest enzymatically active unit are mainly determined by aromatic amino acids. Their interactions have been quantified both by structure-theoretical calculations on the basis of the X-ray crystallography structure, and experimentally by binding of the fluorescent dye bis-ANS. The contact sites of two dimers in tetramer formation, however, are mainly determined by electrostatic interactions. Homomeric pyruvate decarboxylase (PDC) is activated by its substrate pyruvate. There was no difference in the steady-state activity (specific activity) between dimers and tetramers. The activation kinetics of the two oligomeric states, however, revealed differences in the dissociation constant of the regulatory substrate (K(a)) by one order of magnitude. The tetramer formation is related to structural consequences of the interaction transfer in the activation process causing an improved substrate utilization.
Biopolymers↗
The IMB Jena Image Library of biological macromolecules.
The IMB Jena Image Library of Biological Macro-molecules (http://www. imb-jena.de/IMAGE.html ) is aimed at a better dissemination of information on three-dimensional biopolymer structures with an emphasis on visualization and analysis. It provides access to all structure entries deposited at the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). By combining automatic and manual processing it is possible to keep pace with the rapidly growing number of known biopolymer structures and to provide, for selected entries, information not available from automatic procedures. Each entry page contains basic information on the structure, various visualization and analysis tools as well as links to other databases. The visualization techniques adopted include static mono/stereo raster or vector graphics representations, virtual reality modeling (VRML), RasMol/Chime scripts and Java applets. A helix and bending analysis tool provides consistent information on about 750 DNA and RNA duplex structures. Access to metal-containing PDB entries is possible via the Periodic Table of Elements. Finally, general information on amino acids, cis -peptide bonds, structural elements in proteins, base pairs, nucleic acid model conformations and experimental methods for biopolymer structure determination is provided.
Biopolymers↗
Non-proline cis peptide bonds in proteins.
In a non-redundant set of 571 proteins from the Brookhaven Protein Data Base, a total of 43 non-proline cis peptide bonds were identified. Average geometrical parameters of the well-defined cis peptide bonds in proteins determined at high resolution show that some parameters, most notably the bond angle at the amide bond nitrogen, deviate significantly from the corresponding one in the trans conformation. Since the same feature was observed in cis amide bonds in small molecule structures found in the Cambridge Structural Data Base, a new set of parameters for the refinement of protein structures containing non-Pro cis peptide bonds is proposed.A striking preference was observed for main-chain dihedral angles of the residues involved in cis peptide bonds. All residues N-terminal and most residues C-terminal to a non-Pro cis peptide bond (except Gly) are located in the beta-region of a phi/psi plot. Also, all of the few C-terminal residues (except Gly) located in the alpha-region of the phi/psi plot constitute the start of an alpha-helix in the respective structure. In the majority of cases, an intimate side-chain/side-chain interaction was observed between the flanking residues, often involving aromatic side-chains. Interestingly, most of the cases found occur in functionally important regions such as close to the active site of proteins. It is intriguing that many of the proteins containing non-proline cis peptide bonds are carbohydrate-binding or processing proteins. The occurrence of these unusual peptide bonds is significantly more frequent in structures determined at high resolution than in structures determined at medium and low resolution, suggesting that these bonds may be more abundant than previously thought. On the basis of our experience with the structure determination of coagulation factor XIII, we developed an algorithm for the identification of possibly overlooked cis peptide bonds that exploits the deviations of geometrical parameters from ideality. A few likely candidates based on our algorithm have been identified and are discussed.
Algorithms↗
Peptide bonds revisited.
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Crystallography↗
Comment on "Longitudinal coherence in neutron interferometry"
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Journal Article↗
Separation of cis/trans isomers of a prolyl peptide bond by capillary zone electrophoresis.
On capillary electrophoresis of the chemically pure thioxo peptide Ala-Phe-psi[CS-N]-Pro-Phe-4-nitroanilide a peak splitting was observed at a capillary temperature of 25 degrees C. By contrast, the oxo peptide analogue exhibits a single, sharp peak under these conditions. Both peaks of the thioxo compound coincided gradually when the temperature was increased to 60 degrees C. Peak fusion was reverted by cooling down the heated sample. This behavior could be attributed to the electrophoresis-mediated separation of the cis/trans prolyl bond isomers of the thioxo peptide, allowing data of this conformational equilibrium to be determined. Derived from computational data about molecular volume and the hydration energy of low-energy cis and trans isomeric structures, the more rapid migration of the cis form in comparison to trans may be explained by structural parameters.
Algorithms↗