Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties ...of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
Abstract Background Human mesenchymal stem cells (MSC) have been utilized for cardiac regeneration after myocardial damage. Their clinical effects are marginal and only a minority of administered ...cells could make their way into the myocardium. The chemokine receptor CXCR4 has been identified as crucial for migration and homing of stem cells. In this study we overexpressed CXCR4 on human MSC to improve cell trafficking and tissue repair. Methods Human MSC were isolated from the spongiosa of tibia and femur as well as from pelvic bone marrow. MSC were characterized by differentiation assays and FACS analysis. CXCR4 was overexpressed by mRNA-nucleofection. Intracellular signaling was analyzed to demonstrate functionality of CXCR4. The modified Boyden chamber, wounding assays and time lapse microscopy were utilized to investigate MSC migration. Results MSC did not express relevant amounts of CXCR4 spontaneously. CXCR4 could be overexpressed in 93% of MSC with a cell viability of 62%. Functionality of the overexpressed CXCR4 was demonstrated by a significant cytosolic Ca2+ increase and activation of different MAP kinases followed by SDF-1α stimulation. In contrast no improvement of cell migration could be observed. There was a strong basal MSC chemokinesis independent from CXCR4 expression. Conclusions CXCR4 could be effectively overexpressed in human MSC by mRNA-nucleofection. Despite functionality of CXCR4 MSC were characterized by a strong basal chemokinesis that could not be further enhanced by CXCR4 overexpression. As isolation, culture and nucleofection of pelvic bone marrow-derived MSC basically fulfill the GMP-requirements our approach seems suited for an in vivo application in patients.
C-reactive protein (CRP) apheresis may preserve myocardial tissue after acute myocardial infarction with delayed revascularization. Ten consecutive patients with cardiogenic shock were graded using ...the Society of Cardiovascular Angiography and Interventions shock classification and treated with CRP apheresis. All patients tolerated CRP apheresis well and were discharged in good clinical condition.
In this investigation the friction stir welded joint of 5 mm thick AA7075-T651 alloy have been subjected to the post-weld explosive treatment. To assess the influence of the proposed treatment on the ...joint properties, a comprehensive analysis was conducted, including microstructural examination, microhardness testing, static tensile tests, low-cycle fatigue testing, and fracture surface observations. The strain amplitudes of 0.35 %, 0.4 %, 0.5 %, and 0.6 % with asymmetry coefficient R = 0.1, were used for the examined samples. It was concluded that the explosively treated FSW joints are characterized by a lower amplitude of plastic deformation, a reduced number of cycles to failure and show a tendency for cyclic softening. The differences in the fatigue crack propagation primarily concern the initiation area of the crack near the hardened surface. Explosive treatment did not influence the location of material decohesion, which occurs in the low-hardness zone.
Abstract
Background
Second-generation resorbable magnesium scaffold (RMS) Magmaris showed favorable outcomes in clinical trials, especially regarding the incidence of scaffold thrombosis. The earlier ...studies reported a higher occurrence of scaffold recoil with this RMS owing to vessel constriction. This finding was shown to be more prominent in presence of underlying fibrous plaques rather than calcific and/or lipidic lesions. This suggest that sufficient radial force along with longer scaffolding time may improve the device performance. Against this background, DREAMS 3G was developed with stronger mechanical properties despite thinner struts by modifying the magnesium alloy of its predecessor. The first-in-man trial BIOMAG-I demonstrated promising results for the novel RMS with respect to clinical and angiographic outcomes at 6 months follow-up. Still, the data concerning the performance of DREAMS 3G scaffold up to 12-months are lacking.
Purpose
This study aims to assess the influence of the intravascular optical coherence tomography (OCT) -derived underlying plaque characteristics on mean lumen area (mm 2) in patients treated with DREAMS 3G at 6- and 12-months.
Methods
Patients enrolled in the BIOMAG-I trial and who underwent OCT imaging (i) at index-procedure, (ii) at 6-months and (iii) at 12-months follow-up were included in the current analysis. The acquired intravascular imaging data were evaluated every 1 mm on a quadrant basis to assess the presence of fibrous, calcific, or lipidic lesions. We calculated the proportions of each plaque feature per pullback, then assessed their correlation with the mean lumen area obtained at 6- and 12-months follow-up. In addition, we investigated the potential impact of scaffold edge dissection on the mean lumen area.
Results
Fifty-one patients and 52 lesions were evaluated in the current analysis. There was no significant correlation between the underlying plaque characteristic and mean lumen area at 6-months (p=0.767 for fibrous, p=0.761 for calcific, p=0.767 for lipid lesions). This trend was similar at 12 months follow-up (p=0.499 for fibrous, p=0.714 for calcific, p=0.569 for lipid lesions). Finally, the presence of edge dissection did not correlate with mean lumen area (p=0.559 and p=0.670 at 6- and 12-months follow-up, respectively).
Conclusion
The underlying plaque characteristics and the presence of edge dissection had no significant impact on the mean lumen area following DREAMS 3G implantation up to 12 months. These results suggest better device performance with the novel RMS irrespective of the underlying plaque characteristics.
Abstract
Background
The first-in-human trial of the latest resorbable magnesium scaffold (RMS), DREAMS 3G, showed favorable clinical and angiographic outcomes up to 6-months. An intravascular optical ...coherence tomography (OCT) assessment of the vascular healing profile at 6 months and 12 months follow-up may serve as additional supportive evidence for device safety and efficacy.
Purpose
The aim of this study was to evaluate the vessel healing process by quantifying the presence of strut protrusion (SP) and strut degradation following DREAMS 3G implantation as per intravascular OCT imaging.
Methods
Patients from the BIOMAG-I trial who underwent OCT imaging at both 6- and 12-months were deemed eligible. This resulted in the inclusion of a total of 51 patients and 52 lesions in the current analysis. The acquired intravascular imaging data were evaluated every 1 mm to visualize and quantify the SP and the number of visible struts at 6- and 12-months. In addition, we investigated the potential impact of SP on mean and minimum lumen area (mm2) at both time point.
Results
At 12 months, the mean SP area was significantly smaller in comparison to 6 months follow-up (1.87±2.22 mm2 at 6 months vs. 0.99±1.27 mm2 at 12 months, p<0.001). There was a positive correlation between SP area and mean lumen area at both 6 months (p<0.001) and 12 months (p=0.014) follow-up. Similarly, a positive correlation was observed between SP area and minimum lumen area up to 6 months (p=0.006 at 6 months, p=0.323 at 12 months). The number of visible struts was 6.44±7.59 at 6 months and 1.79±0.85 at 12 months (p<0.001).
Conclusion
The SP area was larger in lesions with greater lumen area following the implantation of the novel RMS. The observed SP area was significantly smaller at 12 months in comparison to 6 months follow-up. These results suggest that the presence of SP is part of a favorable vascular healing process following the treatment with the latest resorbable magnesium scaffold.
Abstract
Background/Introduction
Bioresorbable scaffolds have emerged as an attractive alternative to polymeric scaffolds. A 3rd generation drug-eluting resorbable magnesium scaffold (DREAMS 3G) was ...developed to enhance the performance of previous scaffold generations and achieve angiographic outcomes comparable to those of contemporary drug-eluting stents.
Purpose
The aim of the BIOMAG-I first-in-human (FIM) study was to assess the angiographic, clinical and safety performance of DREAMS 3G in patients with de novo coronary artery lesions. We assessed the 12-month safety and performance of this novel device as well intravascular imaging data at baseline, 6- and 12-month follow-up.
Methods
In this prospective, multicentre, non-randomized, first-in-human study 116 subjects with 117 coronary artery lesions were enrolled at 14 centers in Europe. Clinical follow-up was scheduled at 1, 6 and 12-months and annually thereafter until 5 years. Invasive imaging assessments were scheduled 6 and 12-months post-procedure. Vasomotion was assessed in a subgroup of subjects during the 12-months follow-up. The primary endpoint was in-scaffold LLL at six months. Secondary endpoints include in-segment LLL, TLF, clinically driven target lesion revascularization (TLR), cardiac death, target-vessel myocardial infarction (TV-MI) and scaffold thrombosis.
Results
Preliminary in-scaffold LLL (n=89 subjects) remained stable from 6 months (0.20 ± 0.28 mm) to 12 months (0.24 ± 0.35 mm). Interim intravascular ultrasound assessments and optical coherence tomography findings corroborated the QCA results with a preservation of the lumen area from 6 (IVUS: 7.0 ± 2.5 mm2; OCT: 8.1 ± 2.7 mm2) to 12 months (IVUS: 7.2 ± 2.6 mm2; OCT: 7.8 ± 2.6 mm2). Vasomotion assessment in a subgroup of subjects confirmed the motility of the scaffolded segment at 12 months follow up: after Acetylcholine administration: 12.5% ± 7.5 (n=27); after nitro administration: 10.7% ± 9.2 (n=22). Up to 12-months follow up, 3 clinically driven TLR were reported (3.4%). No cardiac death, no TV-MI and no scaffold thrombosis were reported up to 12 months. Full data set of the 116 subjects will be available upon presentation.
Conclusions
The novel third-generation drug-eluting magnesium scaffold, DREAMS 3G, showed a continuous favorable safety and efficacy profile up to 12 months and stable angiographic parameters between 6 and 12 months. Intravascular imaging assessment showed a preservation of the lumen area between 6 and 12 months.
Combined treatment with trypsin, cholesterol esterase, and neuraminidase transforms LDL, but not HDL or VLDL, to particles with properties akin to those of lipid extracted from atherosclerotic ...lesions. Single or double enzyme modifications, or treatment with phospholipase C, or simple vortexing are ineffective. Triple enzyme treatment disrupts the ordered and uniform structure of LDL particles, and gives rise to the formation of inhomogeneous lipid droplets 10-200 nm in diameter with a pronounced net negative charge, but lacking significant amounts of oxidized lipid. Enzymatically modified LDL (E-LDL), but not oxidatively modified LDL (ox-LDL), is endowed with potent complement-activating capacity. As previously found for lipid isolated from atherosclerotic lesions, complement activation occurs to completion via the alternative pathway and is independent of antibody. E-LDL is rapidly taken up by human macrophages to an extent exceeding the uptake of acetylated LDL (ac-LDL) or oxidatively modified LDL. After 16 h, cholesteryl oleate ester formation induced by E-LDL (50 micrograms/ml cholesterol) was in the range of 6-10 nmol/mg protein compared with 3-6 nmol/mg induced by an equivalent amount of acetylated LDL. At this concentration, E-LDL was essentially devoid of direct cytotoxic effects. Competition experiments indicated that uptake of E-LDL was mediated in part by ox-LDL receptor(s). Thus, approximately 90% of 125I-ox-LDL degradation was inhibited by a 2-fold excess of unlabeled E-LDL. Uptake of 125I-LDL was not inhibited by E-LDL. We hypothesize that extracellular enzymatic modification may represent an important step linking subendothelial deposition of LDL to the initiation of atherosclerosis.
Background. The congenitally corrected transposition of the great arteries (L-TGA) is a very rare congenital heart defect, which often remains undetected for several decades of life. Case ...Presentation. We report on a 45-year-old man without prior history of heart disease, presenting with cardiac shock related to a first episode of tachycardic atrial fibrillation. The diagnostic work-up identified a L-TGA as the underlying cause for acute heart failure. Discussion. L-TGA is a very rare congenital heart defect, which is characterized by an atrioventricular as well as a ventriculoarterial discordance. By this means, the physiological sequence of pulmonary and systemic circulation is still maintained. On the basis of an ongoing strain of the right ventricle, which has to carry the burden of the systemic blood pressure, after more than four decades without symptoms, acute heart failure was triggered by a tachycardic atrial fibrillation.
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