Experimental validation of a mean field model of mineralized collagen fiber arrays at two levels of hierarchy

In the course of this study, stiffness of a fibril array of mineralized collagen fibrils modeled with a mean field method was validated experimentally at site-matched two levels of tissue hierarchy using mineralized turkey leg tendons (MTLT). The applied modeling approaches allowed to model the properties of this unidirectional tissue from nanoscale (mineralized collagen fibrils) to macroscale (mineralized tendon). At the microlevel, the indentation moduli obtained with a mean field homogenization scheme were compared to the experimental ones obtained with microindentation. At the macrolevel, the macroscopic stiffness predicted with micro finite element (μFE) models was compared to the experimental stiffness measured with uniaxial tensile tests. Elastic properties of the elements in μFE models were injected from the mean field model or two-directional microindentations. Quantitatively, the indentation moduli can be properly predicted with the mean-field models. Local stiffness trends within specific tissue morphologies are very weak, suggesting additional factors responsible for the stiffness variations. At macrolevel, the μFE models underestimate the macroscopic stiffness, as compared to tensile tests, but the correlations are strong.

Contrast-enhanced ultrasound for myocardial perfusion imaging.

Ultrasound contrast agents are gas-filled microbubbles that enhance visualization of cardiac structures, function and blood flow during contrast-enhanced ultrasound (CEUS). An interesting cardiovascular application of CEUS is myocardial contrast echocardiography, which allows real-time myocardial perfusion imaging. The intraoperative use of this technically challenging imaging method is limited at present, although several studies have examined its clinical utility during cardiac surgery in the past. In the present review we provide general information on the basic principles of CEUS and discuss the methodology and technical aspects of myocardial perfusion imaging.

Function of Natural Internal Mammary-to-Coronary Artery Bypasses and Its Effect on Myocardial Ischemia.

BACKGROUND The function of naturally existing internal mammary (IMA)-to-coronary artery bypasses and their quantitative effect on myocardial ischemia are unknown. METHODS AND RESULTS The primary end point of this study was collateral flow index (CFI) obtained during two 1-minute coronary artery balloon occlusions, the first with and the second without simultaneous distal IMA occlusion. The secondary study end point was the quantitatively determined intracoronary ECG ST-segment elevation. CFI is the ratio of simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure both subtracted by mean central venous pressure. A total of 180 pairs of CFI measurements were performed among 120 patients. With and without IMA occlusion, CFI was 0.110±0.074 and 0.096±0.072, respectively (P<0.0001). The difference of CFI obtained in the presence minus CFI obtained in the absence of IMA occlusion was highest and most consistently positive during left IMA with left anterior descending artery occlusion and during right IMA with right coronary artery occlusion (ipsilateral occlusions): 0.033±0.044 and 0.025±0.027, respectively. This CFI difference was absent during right IMA with left anterior descending artery occlusion and during left IMA with right coronary artery occlusion (contralateral occlusions): -0.007±0.034 and 0.001±0.023, respectively (P=0.0002 versus ipsilateral occlusions). The respective CFI differences during either IMA with left circumflex artery occlusion were inconsistently positive. Intracoronary ECG ST-segment elevations were significantly reduced during ipsilateral IMA occlusions but not during contralateral or left circumflex artery occlusions. CONCLUSION There is a functional, ischemia-reducing extracardiac coronary artery supply via ipsilateral but not via contralateral natural IMA bypasses. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCTO1676207.

Collagen XII: Protecting bone and muscle integrity by organizing collagen fibrils.

Collagen XII, largest member of the fibril-associated collagens with interrupted triple helix (FACIT) family, assembles from three identical α-chains encoded by the COL12A1 gene. The molecule consists of three threadlike N-terminal noncollagenous NC3 domains, joined by disulfide bonds and a short interrupted collagen triple helix toward the C-terminus. Splice variants differ considerably in size and properties: "small" collagen XIIB (220 kDa subunit) is similar to collagen XIV, whereas collagen XIIA (350 kDa) has a much larger NC3 domain carrying glycosaminoglycan chains. Collagen XII binds to collagen I-containing fibrils via its collagenous domain, whereas its large noncollagenous arms interact with other matrix proteins such as tenascin-X. In dense connective tissues and bone, collagen XII is thought to regulate organization and mechanical properties of collagen fibril bundles. Accordingly, recent findings show that collagen XII mutations cause Ehlers-Danlos/myopathy overlap syndrome associated with skeletal abnormalities and muscle weakness in mice and humans.

Suitability of Common Collagen Scaffolds for Anterior Cruciate Ligament Repair

Introduction: Anterior cruciate ligament (ACL) injuries are very common; in Germany incidence of ACL ruptures is estimated at 32 per 100 000 in the general population and in the sports community this rate more than doubles. Current gold standard for anterior cruciate lig- ament repair is reconstruction using an autograft [1]. However, this approach has shown some limitations. A new method has been her- alded by the Knee Team at the Bern University Hospital (Inselspital) and the Sonnenhof clinic called Dynamic Intraligamentary Stabilization (DIS), which keeps ACL remnants in place in order to promote biologi- cal healing and makes use of a dynamic screw system [2]. The aim of this study was to investigate the cytocompatibility of collagen patches in combination with DIS to support regeneration of the ACL. The spe- cific hypothesis we tested was whether MSCs would differentiate towards TCs in co-culture. Materials and methods: Primary Tenocytes (TCs) and human bone marrow derived mesenchymal stem cells (MSCs) were harvested from ACL removed during knee prothesis or from bone marrow aspirations (Ethical Permit 187/10). Cells were seeded on two types of three dimensional carriers currently approved for cartilage repair, Novocart (NC, B. Brown) and Chondro-Gide (CG, Geistlich). These scaffolds comprise collagen structures with interconnecting pores originally developed for seeding of chondrocytes in the case of CG. ~40k cells were seeded on punched zylindrical cores of 8 mm in Ø and cultured on CG or NC patches for up to 7 days. The cells were either cultured as TC only, MSC only or co-cultured in a 1:1 mix on the scaffolds and on both sides of culture inserts (PET, high density pore Ø 0.4 mm, BD, Fal- con) with cell-cell contact. We monitored DNA content, GAG and HOP-content, tracked the cells using DIL and DIO fluorescent dyes (Molecular Probes, Life technologies) and confocal laser scanning and SEM microscopy as well as RT-PCR of tenocyte specific markers (i.e. col 1 and 3, TNC, TNMD, SCXA&B, and markers of dedifferentiation ACAN, col2, MMP3, MMP13). Finally, H&E stain was interpreted on cryosections and SEM images of cells on the scaffold were taken. Results: ThecLSMimagesshowedcellproliferationoverthe7dayson both matrices, however, on CG there were much fewer MSCs attached than on NC. SEM images showed a roundish chondrocyte-like pheno- type of cells on CG whereas on NC the phenotype was more teno- cyte-like (Fig. 1). Gene expression of both, MSC and TC seem to confirm a more favorable environment in 3D for both patches rather than monolayer control.

Mesenchymal stem cells and collagen patches for anterior cruciate ligament repair

AIM: To investigate collagen patches seeded with mesenchymal stem cells (MSCs) and/or tenocytes (TCs) with regards to their suitability for anterior cruciate ligament (ACL) repair. METHODS: Dynamic Intraligamentary Stabilization (DIS) utilizes a dynamic screw system to keep ACL remnants in place and promote biological healing, supplemented by collagen patches. How these scaffolds interact with cells and what type of benefit they provide has not yet been investigated in detail. Primary ACL-derived TCs and human bone marrow derived MSCs were seeded onto two different types of 3D collagen scaffolds, Chondro-Gide® (CG) and Novocart® (NC). Cells were seeded onto the scaffolds and cultured for 7 days either as a pure populations or as “premix” containing a 1 : 1 ratio of TCs to MSCs. Additionally, as controls, cells were seeded in monolayers and in co-cultures on both sides of porous high-density membrane inserts (0.4µm). We analyzed the patches by real time polymerase chain reaction (RT-PCR), glycosaminoglycan (GAG), DNA and hydroxy-proline (HYP) content, was determined. To determine cell spreading and adherence in the scaffolds microscopic imaging techniques, i.e. confocal laser scanning microscopy (cLSM) and scanning electron microscopy (SEM), were applied. RESULTS: CLSM and SEM imaging analysis confirmed cell adherence onto scaffolds. The metabolic cell activity revealed that patches promote adherence and proliferation of cells. The most dramatic increase in absolute metabolic cell activity was measured for CG samples seeded with tenocytes or a 1:1 cell premix. Analysis of DNA content and cLSM imaging also indicated MSCs were not proliferating as nicely as tenocytes on CG. The HYP to GAG ratio significantly changed for the premix group, resulting from a slightly lower GAG content, demonstrating that the cells are modifying the underlying matrix. Real-time quantitative polymerase chain reaction data indicated that MSCs showed a trend of differentiation towards a more tenogenic-like phenotype after 7 days. CONCLUSION: CG and NC are both cyto-compatible with primary MSCs and TCs; TCs seemed to perform better on these collagen patches than MSCs.

Biolimus-eluting stent with biodegradable polymer improves clinical outcomes in patients with acute myocardial infarction

OBJECTIVE To investigate clinical outcomes of coronary intervention using a biolimus-eluting stent (BES) compared with a sirolimus-eluting stent (SES) in patients with acute myocardial infarction (AMI) in the Limus Eluted from A Durable versus ERodable Stent (LEADERS) coating trial at the final 5-year follow-up. METHODS The LEADERS trial is a multicentre all-comer study, where patients (n=1707) were randomised to percutaneous intervention with either BES containing biodegradable polymer or SES containing durable polymer. Out of 1707 patients enrolled in this trial, 573 patients had percutaneous coronary intervention for AMI (BES=280, SES=293) and were included in the current analysis. Patient-oriented composite endpoint (POCE, including all death, all myocardial infarction (MI) and all revascularisations), major adverse cardiac events (MACE, including cardiac death, MI and clinically indicated target vessel revascularisation) and stent thrombosis were assessed at 5-year follow-up. RESULTS The baseline clinical, angiographic and procedural characteristics were well matched between BES and SES groups. In all patients with AMI, coronary intervention with a BES, compared with SES, significantly reduced POCE (28.9% vs 42.3%; relative risk (RR) 0.61, 95% CI 0.47 to 0.82, p=0.001) at 5-year follow-up. There was also a reduction in MACE rate in the BES group (18.2% vs 25.9%; RR 0.67, 95% CI 0.47 to 0.95, p=0.025); however, there was no difference in cardiac death and stent thrombosis. In patients with ST-elevation MI (STEMI), coronary intervention with BES significantly reduced POCE (24.4% vs 39.3%; RR 0.55, 95% CI 0.36 to 0.85, p=0.006), MACE (12.6% vs 25.0%; RR 0.47, 95% CI 0.26 to 0.83, p=0.008) and cardiac death (3.0% vs 11.4%; RR 0.25, 95% CI 0.08 to 0.75, p=0.007), along with a trend towards reduction in definite stent thrombosis (3.7% vs 8.6%; RR 0.41, 95% CI 0.15 to 1.18, p=0.088), compared with SES. CONCLUSIONS BES, compared with SES, significantly improved safety and efficacy outcomes in patients with AMI, especially those with STEMI, at 5-year follow-up. TRIAL REGISTRATION NUMBER NCT 00389220.

Clinical outcomes following regenerative therapy of non-contained intrabony defects using a deproteinized bovine bone mineral combined with either enamel matrix derivative or collagen membrane

BACKGROUND The purpose of this study is to compare clinical outcomes in the treatment of deep non-contained intrabony defects (i.e., with ≥70% 1-wall component and a residual 2- to 3-wall component in the most apical part) using deproteinized bovine bone mineral (DBBM) combined with either enamel matrix protein derivative (EMD) or collagen membrane (CM). METHODS Forty patients with multiple intrabony defects were enrolled. Only one non-contained defect per patient with an intrabony depth ≥3 mm located in the interproximal area of single- and multirooted teeth was randomly assigned to the treatment with either EMD + DBBM (test: n = 20) or CM + DBBM (control: n = 20). At baseline and after 12 months, clinical parameters including probing depth (PD) and clinical attachment level (CAL) were recorded. The primary outcome variable was the change in CAL between baseline and 12 months. RESULTS At baseline, the intrabony component of the defects amounted to 6.1 ± 1.9 mm for EMD + DBBM and 6.0 ± 1.9 mm for CM + DBBM sites (P = 0.81). The mean CAL gain at sites treated with EMD + DBBM was not statistically significantly different (P = 0.82) compared with CM + DBBM (3.8 ± 1.5 versus 3.7 ± 1.2 mm). No statistically significant difference (P = 0.62) was observed comparing the frequency of CAL gain ≥4 mm between EMD + DBBM (60%) and CM + DBBM (50%) or comparing the frequency of residual PD ≥6 mm between EMD + DBBM (5%) and CM + DBBM (15%) (P = 0.21). CONCLUSION Within the limitations of the present study, regenerative therapy using either EMD + DBBM or CM + DBBM yielded comparable clinical outcomes in deep non-contained intrabony defects after 12 months.

Health-related quality of life in European women following myocardial infarction: A cross-sectional study

Background:Coronary heart disease is a major contributor to women's health problems.Design:Self-perceived social support, well-being and health-related quality of life (HRQL) were documented in the cross-sectional HeartQoL survey of European women one and six months after a myocardial infarction.Methods:European women were recruited in 18 European countries and grouped into four geographical regions (Southern Europe, Northern Europe, Western Europe and Eastern Europe). Continuous socio-demographic variables and categorical variables were compared by age and region with ANOVA and χ(2), respectively; multiple regression models were used to identify predictors of social support, well-being and HRQL.Results:Women living in the Eastern European region rated social support, well-being and HRQL significantly lower than women in the other regions. Older women had lower physical HRQL scores than younger women. Eastern European women rated social support, well-being and HRQL significantly lower than women in the other regions. Prediction of the dependent variables (social support, well-being and HRQL) by socio-demographic factors varied by total group, in the older age group, and by region; body mass index and managerial responsibility were the most consistent significant predictors.

Management of ST-elevation myocardial infarction according to European and American guidelines.

AIMS To highlight differences between the most recent guidelines of the European Society of Cardiology (ESC) and the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) on the management of ST-elevation myocardial infarction (STEMI). METHODS AND RESULTS ESC 2012 and ACCF/AHA 2013 guidelines on the management of STEMI were systematically reviewed for consistency. Recommendations were matched, directly compared in terms of class of recommendation and level of evidence, and classified as "identical", "overlapping", or "different". Out of 32 recommendations compared, 26 recommendations (81%) were classified as identical or overlapping, and six recommendations (19%) were classified as different. Most diverging recommendations were related to minor differences in class of recommendation between the two documents. This applies to recommendations for reperfusion therapy >12 hours after symptom onset, immediate transfer of all patients after fibrinolytic therapy, rescue PCI for patients with failed fibrinolysis, and intra-aortic balloon pump use in patients with cardiogenic shock. More substantial differences were observed with respect to the type of P2Y12 inhibitor and duration of dual antiplatelet therapy. CONCLUSIONS The majority of recommendations for the management of STEMI according to ESC and ACCF/AHA guidelines were identical or overlapping. Differences were explained by gaps in available evidence, in which case expert consensus differed between European and American guidelines due to divergence in interpretation, perception, and culture of medical practice. Systematic comparisons of European and American guidelines are valuable and indicate that interpretation of available evidence leads to agreement in the vast majority of topics. The latter is indirect support for the process of review and guideline preparation on both sides of the Atlantic.