Presence Of Microchannels Research Articles

Прогноз пацієнтів із гострим інфарктом міокарда з підйомом сегмента ST після проведення первинного черезшкірного коронарного втручання

Myocardial infarction claims million lives on the planet each year. Ischemic heart injury is diagnosed with increasing incidence among younger people of working age, posing significant medical and social problem. Percutaneous coronary interventions (PCI) are the primary treatment for ST-segment elevation myocardial infarction (STEMI). The aim of the study was to optimize the prognosis of acute STEMI after primary PCI. Materials and methods. The study included 98 patients with STEMI who were undergoing primary PCI. As a part of revascularization procedure, a manual thromboaspiration was performed for each patient. Thrombotic material was obtained at a volume sufficient for histological analysis with further macro- and microscopic examination. Prognosis was assessed by the probability of occurrence of major coronary events, such as death, myocardial infarction, repeated revascularization or reappearance of angina. In order to single out the factors that, when combined, have a reliable influence on the prognosis, a step-by-step method of logistic regression with forward selection was used. To assess the level of plausibility of the obtained model, a pseudo R-square Nagelkerkes analysis, an analogue of R-square for linear regression, was performed. The results. During two years of follow-up, major coronary events occurred in 34 patients (34.69%). After analysis of the obtained data, four characteristics of thrombi were separated, which, when combined, had an impact on the development of the end-point. These were old thrombi, the presence of microchannels, inflammatory infiltration, and macroscopically mixed thrombi. The resulting formula was as follows: Z = 0.5•V2 – 0.04•V1 – 0.1•V3 + 1.77•V4 – 1.51, where V1 = old thrombus, V2 = presence of microchannels, V3 = inflammatory infiltration, V4 = macroscopically mixed thrombus. Conclusions. Analysis of the morphological characteristics of intracoronary thrombi allowed assessing the long-term prognosis in patients with STEMI. Article received: 28.11.2022

Preparation and assessment of an optimized multichannel acellular nerve allograft for peripheral nerve regeneration.

Peripheral nerve regeneration after injury is still a clinical problem. The application of autologous nerve grafting, the gold standard treatment, is greatly restricted. Acellular nerve allografts (ANAs) are considered promising alternatives, but they are difficult to achieve satisfactory therapeutic outcomes, which may be attributed to their compact inherent ultrastructure and substantial loss of extracellular matrix (ECM) components. Regarding these deficiencies, this study developed an optimized multichannel ANA by a modified decellularization method. These innovative ANAs were demonstrated to retain more ECM bioactive molecules and regenerative factors, with effective elimination of cellular antigens. The presence of microchannels with larger pore size allowed ANAs to gain higher porosity and better swelling performance, which improves their internal ultrastructure. Their mechanical properties were more similar to those of native nerves. Moreover, the optimized ANAs exhibited good biocompatibility and possessed significant advantages in supporting the proliferation and migration of Schwann cells in vitro. The in vivo results further confirmed their superior capacity to promote axon regrowth and myelination as well as restore innervation of target muscles, leading to better functional recovery than the conventional ANAs. Overall, this study demonstrates that the optimized multichannel ANAs have great potential for clinical application and offer new insight into the further improvement of ANAs.

Progression from normal vessel wall to atherosclerotic plaque: lessons from an optical coherence tomography study with follow-up of over 5years.

The initial process of atherosclerotic development has not been systematically evaluated. This study aimed to observe atherosclerotic progression from normal vessel wall (NVW) to atherosclerotic plaque and examine local factors associated with such progression using > 5-year long-term follow-up data obtained by serial optical coherence tomography (OCT). A total of 49 patients who underwent serial OCT for lesions with NVW over 5years (average: 6.9years) were enrolled. NVW was defined as a vessel wall with an OCT-detectable three-layer structure and intimal thickness ≤ 300μm. Baseline and follow-up OCT images were matched, and OCT cross sections with NVW > 30° were enrolled. Cross sections were diagnosed as "progression" when the NVW in these cross sections was reduced by > 30° at > 5-year follow-up. Atherogenic progression from NVW to atherosclerotic plaque was observed in 40.8% of enrolled cross sections. The incidence of microchannels in an adjacent atherosclerotic plaque within the same cross section(6.7 vs. 3.3%; p = 0.046) and eccentric distribution of atherosclerotic plaque (25.0 vs. 12.6%; p < 0.001) at baseline was significantly higher in cross sections with progression than in those without. Cross sections with progression exhibited significantly higher NVW intimal thickness at baseline than cross sections without progression (200.1 ± 53.7 vs. 180.2 ± 59.6μm; p < 0.001). Multivariate analysis revealed that the presence of microchannels in an adjacent atherosclerotic plaque, eccentric distribution of atherosclerotic plaque, and greater NVW intimal thickness at baseline were independently associated with progression at follow-up. The presence of microchannels in an adjacent atherosclerotic plaque, eccentric distribution of atherosclerotic plaque, and greater NVW intimal thickness were potentially associated with initial atherosclerotic development from NVW to atherosclerotic plaque.

Prognosis of acute ST-elevation myocardial infarction depending on the morphological features of intracoronary thrombi

Risk stratification among patients with acute ST-segment elevation myocardial infarction (STEMI) is very important. Morphological features of intracoronary thrombus significantly influence the prognosis.Aim. To estimate the prognosis after STEMI treated with primary percutaneous coronary intervention (PCI) depending on the morphological structure of intracoronary thrombi obtained during manual thromboaspiration.Materials and methods. Totally 97 patients with STEMI who underwent primary PCI were included into the study. Morphological structure of intracoronary thrombi obtained by manual thromboaspiration was evaluated in all participants. Further, the different structure of thrombi influence on the risk of developing a composite endpoint was determined, which represented a death, myocardial infarction, revascularization, and angina symptoms onset or worsening. The duration of follow-up was 24 months.Results. In 24 months after primary PCI, the occurrence of the endpoint correlated significantly only with macroscopic signs of intracoronary clots, negatively – with white (r = -0.21, P = 0.05) and red thrombi (r = -0.30, P &lt; 0.01), and positively – with mixed thrombi (r = 0.41, P &lt; 0.001). Using the logistic regression, the factors were revealed which in a case of combined action, may increase the risk of the combined endpoint: old blood clots (V1), the presence of microchannels (V2), peripheral leukocyte infiltration (V3), and gross mixed thrombi (V4). The following model was developed for calculating the probability of these factors influence on the occurrence of cardiovascular events included into the endpoint:Z = 2.37 × V1 + 2.21 × V2 + 1.69 × V3 + 3.24 × V4 - 5.60.The model is reliable (P &lt; 0.0001) with a sensitivity of 83.33 % and a specificity of 88.24 %.Conclusions. Despite the similar clinical manifestations and duration of the disease, intracoronary thrombi that cause STEMI differ significantly. Their morphological characteristics were related to the prognosis. These characteristics may be used for construction of a reliable risk scale that is suitable for clinical practice.

Correlations between morphological features of intracoronary thrombi and left ventricular structure and function in patients with ST-segment elevation myocardial infarction

The majority of cases of acute ST-elevation myocardial infarction (STEMI) are caused by the rupture of an atherosclerotic plaque and subsequent thrombus formation. The study of clot structure may be important for the prediction of further course of the disease. The study included 100 patients with STEMI who underwent primary percutaneous coronary intervention (PCI) with manual thromboaspiration within the first 12 hours after the onset of symptoms. Sufficient aspiration material for histological examination was obtained in 97 patients. These intracoronary thrombi were investigated macroscopically and microscopically. Subsequently, correlations between morphological structure of thrombi and structural and functional features of the myocardium after revascularization were analyzed. Pathological QS pattern was detected in 45 (46.39±5.06%) patients. Peripheral infiltration of intracoronary thrombus with neutrophils was the only morphological feature associated with the presence of QS (r= -0.36; p&lt;0.001). The mean left ventricular ejection fraction (LVEF) measured during echocardiography was 48.34±9.39%. Positive and significant correlation was found between LVEF and peripheral infiltration of intracoronary thrombus with neutrophils (r=0.37; p&lt;0.001), while negative correlation was found between LVEF and presence of microchannels within the clot (r= -0.27; p&lt;0.01). The mean total segmental left ventricular contractility index at the time of hospital discharge was 1.38 [1.25; 1.63]. This index negatively correlated with neutrophil infiltration (r= -0.37; p&lt;0.001), and positively – with the presence of microchannels in the obtained clot samples (r=0.26; p=0.01). Signs of left ventricular aneurysm formation before discharge from the hospital were found in 15 (15.46±3.67%) patients. A significant negative correlation was found between this parameter and the presence of peripheral neutrophil infiltration of intracoronary thrombi (r= -0.32; p&lt;0.01). The presence of peripheral infiltration of intracoronary thrombi with neutrophil leukocytes was associated with better left ventricular systolic function and less likely hood of development of left ventricular aneurysm or electrocardiographic QS pattern. The formation of microchannels within the clot was associated with poorer recovery of systolic cardiac function.

Microchannels Are an Architectural Cue That Promotes Integration and Vascularization of Silk Biomaterials in Vivo.

Functional integration of implanted biomaterials and bioengineered tissues in vivo requires effective and timely vascular ingrowth. While many vascularization strategies rely on delivery of angiogenic growth factors or endothelial cells to promote vascular ingrowth, the effect of physical and architectural features of biomaterials on the vascularization process is less well understood. Microchannels are a simple, accessible architectural feature frequently engineered into 3D biomaterials to promote mass transfer. In this study, the effect of microchannels on the integration and vascularization of 3D porous silk scaffolds was explored over a 14 week period. An array of 508 μm diameter microchannels spanning the length of critically sized, porous silk scaffolds significantly improved tissue ingrowth into the constructs. At week 6, all silk scaffolds (n = 8) with microchannels showed complete tissue infiltration throughout the construct, while only one of eight (12.5%) did so in the absence of microchannels. The presence of microchannels improved silk scaffold vascularization with significantly more vessels per unit area in the presence of microchannels. The vessel size distribution was similar in both scaffold types, but a shift in distribution toward smaller vessels was observed in the presence of microchannels. The blood vessels in silk scaffolds were perfused, functional and connected to the animal's cardiovascular system, as demonstrated by the presence of red blood cells in the vessel lumens, and effective delivery of a contrast agent the vessels inside the scaffold. This study demonstrates the utility of microchannels as a simple architectural feature that significantly improves vascularization and integration of implanted biomaterials.

P3586Influence of morphological features of intracoronary thrombi on ST segment resolution in patients with STEMI after primary PCI

Abstract Background Coronary artery thrombosis is a key element in the onset of STEMI and its further course. Coronary clots significantly vary in their morphological features and types. Perhaps, it may be caused by individual differences in thrombus formation that could have a strong influence on STEMI course and prognosis. Purpose To elucidate the influence of morphological features of intracoronary thrombi (IT) on ST-segment resolution (the outcome) after primary PCI in patients with STEMI. Methods The study included 100 patients with STEMI (female 22%, male 78%) aged 57.81±10.26 years, who underwent PCI with manual thromboaspiration within the first 12 hours (mean 7.22±3.74 h) after the onset of symptoms. The obtained ITs were examined morphologically after hematoxylin &amp; eosin staining by the standard method and by the method proposed by prof. Zerbino that allows determining the antiquity of fibrin according to its color. Each IT was classified by five morphological features: 1) “old” or “fresh” (according to Zerbino's staining); 2) with or without layered structure; and presence or absence of 3) microchannels, 4) peripheral infiltration with neutrophil leukocytes, 5) elements of atherosclerotic plaque. Correlations between these features and incidence of ST-segment resolution in 60 minutes after primary PCI for more than 50% from baseline were analyzed. Results Neither IT antiquity nor presence of the atherosclerotic plaque elements had any significant correlations with ST-segment resolution. Significant positive correlation was revealed with peripheral neutrophil infiltration (r=0.42, p&lt;0.05), and negative correlations were found with layered arrangement IT (r=−0.31, p&lt;0.05) and presence of microchannels (r=−0.56, p&lt;0.05). Statistically significant mathematical prognostic model of ST-segment resolution was obtained after analysis of the co-influence of all five morphological features on the outcome using logistic regression method. It included three IT features significantly correlating with ST-segment resolution: Z = 1.13 − 0.51*V1 − 0.57*V2 − 0.94*V3 where V1 – IT with layered arrangement of fibrin, V2 – IT with microchannels' formation, V3 – IT with peripheral areas of infiltration by the neutrophil leukocytes (1 for the presence of the feature, 0 for its absence). “Old” IT with layered structure Conclusions Morphological features of IT in patients with acute STEMI appear to have significant influence on the primary PCI outcomes. They may be important predictors of the disease course and treatments efficacy. Further investigations of the IT peculiarities and their influences on the course of STEMI may help to improve therapy. Acknowledgement/Funding Study financial support was made by authors

High Performance of Asymmetric Alumina Hollow Fiber Membranes for the Clarification of Genipap (Genipa americana L.) Fruit Extract

Membrane filtration processes represent a suitable alternative for fruit juice treatment, but the applied membrane should present high stability and permeability. Here, we propose the development and application of ceramic asymmetric hollow fiber membranes for genipap extract clarification. Genipap is an exotic fruit from Central and South America with considerable concentration of phenolic and iridoid compounds. The dual-layer ceramic hollow fiber membrane was fabricated by a single-step co-extrusion and co-sintering process. The developed hollow fibers presented the desired asymmetric structure, with an inner finger-like region that guaranteed a suitable permeate flux (191 L h−1 m−2 at 1 bar), while the outer sponge-like layer was responsible for solid retentions and for the membrane mechanical resistance. Reductions in turbidity, total polyphenol content, and genipin concentration were of 52, 17, and 4%, respectively. Mathematical modeling of the experimental flux decay showed that pore blocking was the main fouling mechanism during filtrations of genipap extract through the asymmetric hollow fibers. The presence of microchannels with larger pore size in the inner surface of the fiber probably mitigated cake formation. The increase in the transmembrane pressure from 1 to 2 bar did not improve the permeation flux through the membrane since the fouling layer resistance was considerably higher at 2 bar than at 1 bar. Thus, asymmetric ceramic hollow fibers are suggested for juice fruit clarification with improved permeate flux and clarification degree.

Which parameters are important before attempting chronic total occlusions recanalization?

Which parameters are important before attempting chronic total occlusions recanalization?

A Novel Separation Method of Microthrix parvicella Filaments from Activated Sludge by a Hydrophobic Plate.

The aim of this paper is to develop a novel method to separate Microthrix parvicella (M. parvicella) filaments from activated sludge easily and quickly, as there are a few difficulties in the isolation of M. parvicella filaments, such as complicated isolation process, time consuming, etc. In this work, a series of hydrophobic plate with and without microchannels have been prepared for the separation of M. parvicella filaments. The results showed that the presence of microchannels and hydrophobic property of the hydrophobic plates affected the separation efficiency of M. parvicella significantly. The scanning electron microscope and Keyence Digital Microscope analysis results showed that the diameter of microchannels was similar to the width of M. parvicella filament, which was beneficial for the fastening of M. parvicella filaments on the plate. The hydrophobic property of the prepared plates was tested by contact angle of water droplets, and the results displayed that the polydimethylsiloxane (PDMS) plate possessed the highest contact angle compared with that of other plates, like polymethylmethacrylate, polystyrene plate, and PDMS plate with no hydrophobic microchannels. Thus, it was concluded that the high separation efficiency of PDMS plates to M. parvicella filaments was due to its best hydrophobic property.

Relation of Microchannel Structure Identified by Optical Coherence Tomography to Plaque Vulnerability in Patients With Coronary Artery Disease

Increased neovascularization in atherosclerotic plaques is associated with plaque vulnerability. The high resolution of optical coherence tomography (OCT) might provide a chance to directly visualize plaque neovascularization in vivo. The aim of the present study was to investigate the relation between microchannels in culprit plaques identified by OCT and plaque vulnerability in patients with coronary artery disease. A total of 63 consecutive patients with coronary artery disease who had undergone both OCT and intravascular ultrasound before any interventions to examine culprit lesion morphologies were enrolled. Microchannel was defined as a no-signal tubuloluminal structure on the cross-sectional optical coherence tomographic image. Microchannels were found in 24 (38%) of the 63 patients. The patients were divided into 2 groups according to the presence or absence of microchannels. The frequency of plaque rupture tended to be greater in the microchannel group (50% vs 28%, p = 0.11). The thickness of the fibrous cap (median 60 vs 100 microm, p = 0.001) was significantly less in the patients with microchannels, and significant differences were found in the frequency of thin-cap fibroatheroma (54% vs 21%, p = 0.012) and positive remodeling (67% vs 36%, p = 0.02) between the 2 groups. The high-sensitivity C-reactive protein levels in the microchannel group was significantly greater than those in the no-microchannel group (median 0.27 vs 0.13 mg/dl, p = 0.015). Moreover, increased microchannel counts were associated with greater high-sensitivity C-reactive protein levels (p = 0.01). In conclusion, a significant relation was found between the presence of microchannels in plaques identified by OCT and plaque vulnerability in patients with coronary artery disease.

Development of deterministic-stochastic surface structures to improve the tribological conditions of sheet forming processes

In sheet-forming processes with mixed frictional state the tribological system is characterized to a great extent by the sheet-surface structure. This structure has the functions of storage, transport, and distribution of the lubricant, and take-up and transport of surface-abrasion particles. These functional characteristics are achieved by different of surface structure, the so-called stochastic and deterministic structures. The presence of micro channels connecting the surface pockets in stochastic structures allows the distribution of the lubricant in all directions but it is not possible to detain this lubricant in areas under high pressure, it simply flows aside. This ability is given by the isolated surface pockets ( hydrostatic lubrication pockets) in deterministic structures. From this micro reservoirs the lubricant can be transported directly into the deformation zone by means of building up a hydrostatic pressure. However, because of the absence of micro channels it is not possible to transport the lubricant to all areas of micro contact between tool and sheet, the risk of cold-welding effects increases. Therefore, a new type of surface structure is developed by the combination of a deterministic and a stochastic sheet-surface structure. The results of strip-drawing experiments point out that the combination between isolated lubrication pockets and a network of micro channels to transport the lubricant in the space between these surface pockets leads to a improvement of the forming behaviour.