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| 2. |
- Siegel, G., et al.
(author)
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Lipoprotein binding to anionic biopolyelectrolytes and the effect of glucose on nanoplaque formation in arteriosclerosis and Alzheimer's disease
- 2016
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In: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 232, s. 25-35
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Journal article (peer-reviewed)abstract
- Arteriosclerosis with its clinical sequelae (cardiac infarction, stroke, peripheral arterial occlusive disease) and vascular/Alzheimer dementia not only result in far more than half of all deaths but also represent dramatic economic problems. The reason is, among others, that diabetes mellitus is an independent risk factor for both disorders, and the number of diabetics strongly increases worldwide. More than one-half of infants in the first 6 months of life have already small collections of macrophages and macrophages filled with lipid droplets in susceptible segments of the coronary arteries. On the other hand, the authors of the Bogalusa Heart Study found a strong increase in the prevalence of obesity in childhood that is paralleled by an increase in blood pressure, blood lipid concentration, and type 2 diabetes mellitus. Thus, there is a clear linkage between arteriosclerosis/Alzheimer's disease on the one hand and diabetes mellitus on the other hand. Furthermore, it has been demonstrated that distinct apoE isoforms on the blood lipids further both arteriosclerotic and Alzheimer nanoplaque formation and therefore impair flow-mediated vascular reactivity as well. Nanoplaque build-up seems to be the starting point for arteriosclerosis and Alzheimer's disease in their later full clinical manifestation. In earlier work, we could portray the anionic biopolyelectrolytes syndecan/perlecan as blood flow sensors and lipoprotein receptors in cell membrane and vascular matrix. We described extensively molecular composition, conformation, form and function of the macromolecule heparan sulfate proteoglycan (HS-PG). In two supplementary experimental settings (ellipsometry, myography), we utilized isolated HS-PG for in vitro nanoplaque investigations and isolated human coronary artery segments for in vivo tension measurements. With the ellipsometry-based approach, we were successful in establishing a direct connection on a molecular level between diabetes mellitus on the one side and arteriosclerosis/Alzheimer's disease on the other side. Application of glucose at a concentration representative for diabetics and leading to glycation of proteins and lipids, entailed a significant increase in arteriosclerotic and Alzheimer nanoplaque formation. IDLapoE4/E4 was by far superior to IDLapoE3/E3 in plaque build-up, both in diabetic and non-diabetic patients. Recording vascular tension of flow-dependent reactivity in blood substitute solution and under application of different IDLapoE isoforms showed an impaired vasorelaxation for pooled IDL and IDLapoE4/E4, thus confirming the ellipsometric investigations. Incubation in IDLapoE0/E0 (apoE "knockout man"), however, resulted in a massive flow mediated contraction, also complemented" by strongly aggregated nanoplaques. In contrast, HDL was shown to present a powerful protection against nanoplaque formation on principle, both in the in vitro model and the in vivo scenario on the endothelial cell membrane. The competitive interplay with LDL is highlighted through the flow experiment, where flow-mediated, HDL-induced vasodilatation remains untouched by additional incubation with LDL. This is due to the four times higher affinity for the proteoglycan receptor of HDL as compared to LDL. Taken together, the studies demonstrate that while simplistic, the ellipsometry approach and the endothelial mimicking proteoglycan-modified surfaces provide information on the initial steps of lipoprotein-related plaque formation, which correlates with findings on endothelial cells and blood vessels, and afford insight into the role of lipoprotein deposition and exchange phenomena at the onset of these pathophysiologies.
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| 3. |
- Dias, R, et al.
(author)
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DNA-lipid systems. A physical chemistry study
- 2002
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In: Brazilian Journal of Medical and Biological Research. - 0100-879X. ; 35:5, s. 509-522
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Journal article (peer-reviewed)abstract
- It is well known that the interaction of polyelectrolytes with oppositely charged surfactants leads to an associative phase separation; however, the phase behavior of DNA and oppositely charged surfactants is more strongly associative than observed in other systems. A precipitate is formed with very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. Techniques like phase diagram determinations, fluorescence microscopy, and ellipsometry were used to study these systems. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was also investigated. We observed that DNA compacts and adsorbs onto the surface of positively charged vesicles, and that the addition of an anionic surfactant can release DNA back into solution from a compact globular complex between DNA and the cationic surfactant. Finally, DNA interactions with polycations, chitosans with different chain lengths, were studied by fluorescence microscopy, in vivo transfection assays and cryogenic transmission electron microscopy. The general conclusion is that a chitosan effective in promoting compaction is also efficient in transfection.
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| 4. |
- Généreux, Philippe, et al.
(author)
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Evolution and Prognostic Impact of Cardiac Damage After Aortic Valve Replacement.
- 2022
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In: Journal of the American College of Cardiology. - 1558-3597.
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Journal article (peer-reviewed)abstract
- The impact of aortic valve replacement (AVR) on progression/regression of extra-valvular cardiac damage and its association with subsequent prognosis is unknown.To describe evolution of cardiac damage post-AVR and its association with outcomes.Patients undergoing transcatheter or surgical AVR from the PARTNER 2 and 3 trials were pooled and classified by cardiac damage stage at baseline and 1-year (Stage 0, no damage; Stage 1, left ventricular damage; Stage 2, left atrial or mitral valve damage; Stage 3, pulmonary vasculature or tricuspid valve damage; Stage 4, right ventricular damage). Proportional hazards models determined association between change in cardiac damage post-AVR and 2-year outcomes.Among 1974 patients, 121 (6.1%) were Stage 0, 287 (14.5%) Stage 1, 1014 (51.4%) Stage 2, 412 (20.9%) Stage 3, and 140 (7.1%) Stage 4 pre-AVR. Two-year mortality was associated with extent of cardiac damage at baseline and 1-year. Compared with baseline, cardiac damage improved in ∼15%, remained unchanged in ∼60%, and worsened in ∼25% of patients at 1-year. One-year change in cardiac damage stage was independently associated with mortality (adjHR for improvement=0.49; no change=1.0; worsening=1.95; p=0.023) and composite of death or heart failure hospitalization (adjHR for improvement=0.60; no change=1.0; worsening=2.25; p<0.001) at 2 years.In patients undergoing AVR, extent of extravalvular cardiac damage at baseline and its change at 1-year have important prognostic implications. These findings suggest that earlier detection of AS and intervention prior to development of irreversible cardiac damage may improve global cardiac function and prognosis.
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| 6. |
- Siegel, Günter, et al.
(author)
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Flow sensing in the cardiovascular system
- 2015
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In: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 480, s. 318-327
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Journal article (peer-reviewed)abstract
- Background: This contribution deals with chemical processes at the biological membranes of endothelial cells in blood vessels. A basic observation is that the intensity of blood flow navigates the vascular width through a negative feedback circle. When the blood flow increases, the vessels become wider; when it decreases the vascular smooth muscle cells contract. The anionic polyelectrolyte heparan sulfate proteoglycan (HS-PG) reacts to the shear stress generated by the flowing blood. In the present investigation, this naturally occurring biosensor is characterized in more detail, which is crucially involved in the regulation of peripheral blood flow and organ perfusion. A dysfunction of this sensor can lead to organ insufficiency, hypertension and arteriosclerosis.
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| 7. |
- Wilking, N., et al.
(author)
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Long-term follow-up of the SBG 9401 study comparing tailored FEC-based therapy versus marrow-supported high-dose therapy
- 2007
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In: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 18:4, s. 694-700
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Journal article (peer-reviewed)abstract
- Background: The purpose was to investigate adjuvant marrow-supportive high-dose chemotherapy compared with an equitoxicity-tailored comparator arm. Patients and methods: Five hundred and twenty-five women below theage of 60 years with operated high-risk primary breast cancer were randomised to nine cycles of granulocyte colony-stimulating factor supported and individually tailored FEC (5-fluorouracil, epirubicin, cyclophosphamide), (n = 251) or standard FEC followed by marrow-supported high-dose therapy with CTCb (cyclophosphamide, thiotepa, carboplatin) therapy (n = 274), followed by locoregional radiotherapy and tamoxifen for 5 years. Results: There were 104 breast cancer relapses in the tailored FEC group versus 139 in the CTCb group (double triangular method by Whitehead, P = 0.046), with a median follow-up of all included patients of 60.8 months. The event-free survival demonstrated 121 and 150 events in the tailored FEC- and CTCb group, respectively [P = 0.074, hazard ratio (HR) 0.804, 95% confidence interval (CI) 0.633-1.022]. Ten patients in the tailored FEC regimen developed acute myeloid leukaemia (AML)/myelodysplasia (MDS). One hundred deaths occurred in the tailored FEC group and 121 in the CTCb group (P = 0.287, HR 0.866, 95% CI 0.665-1.129). Conclusion: The update of this study shows an improved outcome linked to the tailored FEC treatment in relation to breast cancer relapse, but also an increased incidence of AML/MDS. © 2007 Oxford University Press.
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| 8. |
- Öhlin, Axel, 1990, et al.
(author)
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Protocol for a multicenter prospective cohort study evaluating arthroscopic and non-surgical treatment for microinstability of the hip joint
- 2022
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 23:1
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Journal article (peer-reviewed)abstract
- Background: Microinstability of the hip joint is a proposed cause of hip pain and reduced function in young individuals. The underlying mechanism is thought to be extraphysiological hip motion due to bony deficiency and/or soft tissue deficiency or decreased soft tissue function. Recently, the condition has gained increased attention, and despite the fact that treatment today includes both non-surgical and surgical approaches, there is limited evidence on diagnostic specificity and treatment effects. The aim of this study is to evaluate clinical outcomes of both nonsurgical and surgical treatment for microinstability of the hip joint. Methods: A multicenter prospective cohort study is planned to evaluating the outcome of physical therapy aimed at stabilizing the hip joint, as well as arthroscopic plication of the hip joint capsule, if the physical therapy fails. Outcomes will be evaluated using hip-specific patient-reported outcome measures: the short version of the International Hip Outcome Tool and the Copenhagen Hip and Groin Outcome Score, strength and function tests, health-related quality of life as determined using the European Quality of Life-5 Dimensions and the European Quality of Life-Visual Analog Scale, sports activity levels according to the Hip Sport Activity Scale, and reported complications. Patients will be evaluated at 6, 12 and 24 months after each treatment. Discussion: It is important to evaluate the clinical outcomes of both non-surgical and surgical treatment for suspected microinstability of the hip joint, and the planned prospective evaluation will contribute to the understanding of non-surgical as well as surgical treatment outcomes, including complications.
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| 9. |
- Antunes, Filipe, et al.
(author)
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Network formation of catanionic vesicles and oppositely charged polyelectrolytes. Effect of polymer charge density and hydrophobic modification
- 2004
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 20:11, s. 4647-4656
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Journal article (peer-reviewed)abstract
- In nonequimolar solutions of a cationic and an anionic surfactant, vesicles bearing a net charge can be spontaneously formed and apparently exist as thermodynamically stable aggregates. These vesicles can associate strongly with polymers in solution by means of hydrophobic and/or electrostatic interactions. In the current work, we have investigated the rheological and microstructural properties of mixtures of cationic polyelectrolytes and net anionic sodium dodecyl sulfate/didodecyldimethylammonium bromide vesicles. The polyelectrolytes consist of two cationic cellulose derivatives with different charge densities; the lowest charge density polymer contains also hydrophobic grafts, with the number of charges equal to the number of grafts. For both systems, polymer-vesicle association leads to a major increase in viscosity and to gel-like behavior, but the viscosity effects are more pronounced for the less charged, hydrophobically modified polymer. Evaluation of the frequency dependence of the storage and loss moduli for the two systems shows further differences in behavior: while the more long-lived cross-links occur for the more highly charged hydrophilic polymer, the number of cross-links is higher for the hydrophobically modified polymer. Microstructure studies by cryogenic transmission electron microscopy indicate that the two polymers affect the vesicle stability in different ways. With the hydrophobically modified polymer, the aggregates remain largely in the form of globular vesicles and faceted vesicles (polygon-shaped vesicles with largely planar regions). For the hydrophilic polycation, on the other hand, the surfactant aggregate structure is more extensively modified: first, the vesicles change from a globular to a faceted shape; second, there is opening of the bilayers leading to holey vesicles and ultimately to considerable vesicle disruption leading to planar bilayer, disklike aggregates. The faceted shape is tentatively attributed to a crystallization of the surfactant film in the vesicles. It is inferred that a hydrophobically modified polyion with relatively low charge density can better stabilize vesicles due to formation of molecularly mixed aggregates, while a hydrophilic polyion with relatively high charge density associates so strongly to the surfactant films, due to strong electrostatic interactions, that the vesicles are more perturbed and even disrupted.
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| 10. |
- Campion, James, 1989-, et al.
(author)
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Toward Industrial Exploitation of THz Frequencies : Integration of SiGe MMICs in Silicon-Micromachined Waveguide Systems
- 2019
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In: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 9:6, s. 624-636
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Journal article (peer-reviewed)abstract
- A new integration concept for terahertz (THz) systems is presented in this article, wherein patterned silicon-on-insulator wafers form all DC, IF, and RF networks in a homogeneous medium, in contrast to existing solutions. Using this concept, silicon-micromachined waveguides are combined with silicon germanium (SiGe) monolithic microwave integrated circuits (MMICs) for the first time. All features of the integration platform lie in the waveguide’s H-plane. Heterogeneous integration of SiGe chips is achieved using a novel in-line H-plane transition. As an initial step toward complete systems, we outline the design, fabrication, and assembly of back-to-back transition structures, for use at D-band frequencies (110ï¿œ170 GHz). Special focus is given to the industrial compatibility of all components, fabrication, and assembly processes, with an eye on the future commercialization of THz systems. Prototype devices are assembled via two distinct processes, one of which utilizes semiautomated die-bonding tools. Positional and orientation tolerances for each process are quantified. An accuracy of $\pm \text3.5\; μ \textm$, $\pm \text1.5 °$ is achieved. Measured $S$-parameters for each device are presented. The insertion loss of a single-ended transition, largely due to MMIC substrate losses, is 4.2ï¿œ5.5 dB, with a bandwidth of 25 GHz (135ï¿œ160 GHz). Return loss is in excess of 5 dB. Measurements confirm the excellent repeatability of the fabrication and assembly processes and, thus, their suitability for use in high-volume applications. The proposed integration concept is highly scalable, permitting its usage far into the THz frequency spectrum. This article represents the first stage in the shift to highly compact, low-cost, volume-manufacturable THz waveguide systems.
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