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In vitro calcification studies on bioprosthetic and decellularized heart valves under quasi-physiological flow conditions

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Bio-Design and Manufacturing 2021年第1期4卷 10-21页

作者： Cristian C.D’Alessandro Andreas Dimopoulos Sofia Andriopoulou Gerasimos A.T.Messaris Sotirios Korossis petros koutsoukos Dimosthenis Mavrilas Laboratory of Biomechanics and Biomedical Engineering Department of Mechanical Engineering and AeronauticsUniversity of PatrasPatrasGreece Department of Cardiothoracic Transplantation and Vascular SurgeryHannover Medical SchoolHannoverGermany Department of Medical Physics University Hospital of PatrasPatrasGreece Wolfson School of Mechanical Electrical and Manufacturing EngineeringLoughborough UniversityLoughboroughUK Department of Chemical Engineering University of PatrasPatrasGreece FORTH-Institute of Chemical Engineering Sciences PatrasGreece

The lifespan of biological heart valve prostheses available in the market is limited due to structural alterations caused by calcium phosphate deposits formed from blood plasma in contact with the *** objective of this work is to present a comparative methodology for the investigation of the formation of calcium phosphate deposits on bioprosthetic and tissue-engineered scaffolds in vitro and the influence of mechanical forces on tissue *** on earlier investigations on biological mineralization at constant supersaturation,a circulatory loop simulating dynamic blood flow and physiological pressure conditions was *** system was appropriately adapted to evaluate the calcification potential of decellularized(DCV)and glutaraldehyde-fixed(GAV)porcine aortic *** indicated that DCV calcified at higher,statistically nonsignificant,rates in comparison with *** difference was attributed to the tissue surface modifications and cell debris leftovers from the decellularization *** analysis of the solids deposited after 20 h by scanning electron microscopy in combination with chemical microanalysis electron-dispersive spectroscopy identified the solid formed as octacalcium phosphate(Ca8(PO4)6H2·5H2O,OCP).OCP crystallites were preferentially deposited in high mechanical stress areas of the test ***,GAV tissues developed a significant transvalvular pressure gradient increase past 36 h with a calcium deposition distribution similar to the one found in explanted *** conclusion,the presented in vitro circulatory model serves as a valuable prescreening methodology for the investigation of the calcification process of bioprosthetic and tissue-engineered valves under physiological mechanical load.

关键词： Reactors Calcification Constant composition reactor Heart valve In vitro Mechanical load Tissue engineering

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Model Reference Adaptive Control for Networked Distributed Systems with Strong Interconnections and Communication Delays

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Journal of Systems Science & Complexity 2018年第1期31卷 38-68页

作者： LYMPEROPOULOS Georgios IOANNOU petros Department of Electrical Engineering University of Southern California

In recent years, networked distributed control systems（NDCS） have received research attention. Two of the main challenges that such systems face are possible delays in the communication network and the effect of strong interconnections between agents. This paper considers an NDCS that has delays in the communication network, as well as strong interconnections between its agents. The control objective is to make each agent track efficiently a reference model by attenuating the effect of strong interconnections via feedback based on the delayed information. First, the authors assume that each agent knows its own dynamics, as well as the interconnection parameters, but receives information about the states of its neighbors with some communication delay. The authors propose a distributed control scheme and prove that if the interconnections can be weakened and if the communication delays are small enough, then the proposed scheme guarantees that the tracking error of each agent is bounded with a bound that depends on the size of the weakened interconnections and delays, and reduces to zero as these uncertainties reduce to zero. The authors then consider a more realistic situation where the interconnections between agents are unknown despite the cooperation and sharing of state information. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense with respect to the size of the weakened interconnections and delays, provided the weakened interconnections and time delays are small enough. The authors then consider the case that each agent knows neither its dynamics nor the interconnection matrices. For this case the authors propose a distributed adaptive control scheme and prove that the proposed scheme guarantees that the tracking errors are bounded and small in the mean square sense provided the weakened interconnections and time delays are

关键词： Adaptive control network distributed control delay systems

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Developmental engineering： design of clinically efficacious bioartificial tissues through developmental and systems biology

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Science China(Life Sciences) 2018年第8期61卷 978-981页

作者： petros Lenas Laertis Ikonomou College of Science Harbin Institute of Technology Shenzhen Shenzhen 518055 China Center for Regenerative Medicine of Boston University and Boston Medical Center Boston MA 02118 USA

THE CREATION OF A NEW RESEARCH FIELD： FUNG＇S IDEA ON ENGINEERING TISSUESTissue engineering emerged three decades ago as a distinct research field with the goal to radically change the clinical practice by fabricating in vitro cell-biomaterial assemblies, bioartificial tissues, that could be used as biological tissue substitutes to restore, maintain or improve the functions of diseased or damaged tissues and to eventually solve the problem of organ shortage for transplantations.

关键词：系统生物学纸巾临床工程设计织物

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Inflammatory pouch disease: The spectrum of pouchitis

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World Journal of Gastroenterology 2015年第29期21卷 8739-8752页

作者： petros Zezos Fred Saibil Division of Gastroenterology Department of Medicine Sunnybrook Health Sciences Centre University of Toronto

Restorative proctocolectomy with ileal-pouch anal anastomosis(IPAA) is the operation of choice for medically refractory ulcerative colitis(UC), for UC with dysplasia, and for familial adenomatous polyposis(FAP). IPAA can be a treatment option for selected patients with Crohn's colitis without perianal and/or small bowel disease. The term "pouchitis" refers to nonspecific inflammation of the pouch and is a common complication in patients with IPAA; it occurs more often in UC patients than in FAP patients. This suggests that the pathogenetic background of UC may contribute significantly to the development of pouchitis. The symptoms of pouchitis are many, and can include increased bowel frequency, urgency, tenesmus, incontinence, nocturnal seepage, rectal bleeding, abdominal cramps, and pelvic discomfort. The diagnosis of pouchitis is based on the presence of symptoms together with endoscopic and histological evidence of inflammation of the pouch. However, "pouchitis" is a general term representing a wide spectrum of diseases and conditions, which can emerge in the pouch. Based on the etiology we can sub-divide pouchitis into 2 groups: idiopathic and secondary. In idiopathic pouchitis the etiology and pathogenesis are still unclear, while in secondary pouchitis there is an association with a specific causative or pathogenetic factor. Secondary pouchitis can occur in up to 30% of cases and can be classified as infectious, ischemic, non-steroidal antiinflammatory drugs-induced, collagenous, autoimmuneassociated, or Crohn's disease. Sometimes, cuffitis or irritable pouch syndrome can be misdiagnosed as pouchitis. Furthermore, idiopathic pouchitis itself can be sub-classified into types based on the clinical pattern, presentation, and responsiveness to antibiotic treatment. Treatment differs among the various forms of pouchitis. Therefore, it is important to establish the correct diagnosis in order to select the appropriatetreatment and further management. In this editoria

关键词： Pouchitis Idiopathic pouchitis Secondarypouchitis Ulcerative colitis, Crohn's disease

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Pathogenesis of overactive bladder and surgical treatment according to the Integral Theory Paradigm

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Gynecology and Obstetrics Clinical Medicine 2021年第2期1卷 55-61页

作者： Peter petros Formerly University of NSW Professorial Dept of Surgery St Vincent’s Hospital SydneyAustralia School of Mechanical and Mathematical Engineering University of Western AustraliaPerthWAAustralia

Overactive bladder(OAB is a definition by the International Continence Society(ICS).It comprises three symptoms,urge,frequency and *** is a major problem for up to 30%of women,more so for elderly *** is generally assumed to be a paradigm,but it cannot meet the criteria of a paradigm,as its causation is said to be"idiopathic"(unknown)and is said to have no known *** 1993,it was demonstrated that the sequence of events in urodynamically diagnosed detrusor overactivity(now"DO")was identical with what occurred in normal micturition,which led to the conclusion that frequency,urgency,nocturia were in effect,an uncontrolled but otherwise normal *** from a 1997 experiment indicated the control mechanism of the bladder was binary,either closed or open,regulated by a peripheral musculoligamentous system under cortical *** Integral Theory paradigm's view of OAB is based on and is compatible with,ICS definitions and *** Integral Theory paradigm(ITP)views OAB pathogenesis as anatomical,caused by defects anywhere along the control mechanism pathway,but mainly damage in its weakest link,collagen defects in the peripheral musculoligamentous *** tests to prove causation consist of mechanically supporting suspensory ligaments,pubourethral ligament(PUL)or uterosacral ligament(USL),"simulated operations";PUL support prevents urine loss on coughing;USL support by inserting the lower blade of a bivalve speculum into the vagina diminishes urge and *** ITP specifies treatment of correctible causes:squatting-based exercises to strengthen the reflex pelvic muscles,ligament repair by plication for premenopausal women,slings for postmenopausal women.

关键词： bladder treatment otherwise

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Integrated control of highway traffic flow

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Journal of Control and Decision 2018年第1期5卷 19-41页

作者： Yihang Zhang petros A.Ioannou Department of Electrical Engineering University of Southern CaliforniaLos AngelesCAUSA

Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change *** of these techniques reported significant traffic mobility improvements in macroscopic simulations,which cannot be confirmed in some microscopic simulation *** demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity *** this paper,a lane change controller is proposed which provides lane change recommendations to avoid the capacity *** with the lane change control,a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is *** integrated VSL,RM and LC controller can improve system performance,manage the ramp queues and maintain the fairness between mainline and on-ramp *** simulations show consistent improvements under different scenarios.

关键词： Variable speed limit lane change ramp metering feedback linearisation

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Web-based learning in inflammatory bowel diseases:General truths and current specifics

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World Journal of Clinical Cases 2018年第11期6卷 410-417页

作者： petros Zezos Daniel Panisko Division of Gastroenterology Department of Internal MedicineThunder Bay Health Sciences CentreNorthern Ontario School of Medicine Master Teacher Program Department of MedicineUniversity of Toronto

In a field rapidly evolving over the past few years, the management of inflammatory bowel diseases(IBD), Crohn's disease and ulcerative colitis, is becoming in-creasingly complex, demanding and challenging. In the recent years, IBD quality measures aiming to improve patients' care have been developed, multiple new medical therapies have been approved, new treatment goals have been set with the "treat--to--target" concept and drug monitoring has been implemented into IBD clinical management. Moreover, patients are increasingly using Internet resources to obtain information about their health conditions. The healthcare professional with an interest in treating IBD patients should deal with all these challenges in everyday practice by establishing, enhancing and maintaining a strong core of knowledge and skills related to IBD. This is an ongoing process and traditionally these needs are covered with additional reading of textbook or journal articles, attendance at meetings or conferences, or at local rounds. Web--based learning resources expand the options for knowledge acquisition and save time and costs as well. In the new era of communications technology, web-based resources can cover the educational needs of both patients and healthcare professionals and can contribute to improvement of disease management and patient care. Healthcare professionals can individually visit and navigate regularly relevant websites and tailor choices for educational activities according to their existing needs. They can also provide their patients with a few certified suitable internet resources. In this review, we explored the Internet using PubMed and Startpage(Google), for web-based IBD--related educational resources aiming to provide a guide for those interested in obtaining certified knowledge in this subject.

关键词： Inflammatory bowel diseases Ulcerative colitis Crohn’s disease Technology-enhanced learning E-learning Web-based learning Continuing medical education

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Residual tree damage along skidding trails in beech stands in Greece

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Journal of Forestry Research 2015年第2期26卷 523-531页

作者： petros A.Tsioras Diamantis K.Liamas Laboratory of Forest Utilization Faculty of Forestry and Natural EnvironmentAristotle University of Thessaloniki

We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting *** timber was harvested we recorded and analyzed all damage to a width of 2 m along both sides of the skid *** percentage of damaged residual trees was 17–28 %.Higher numbers of saplings were uprooted or destroyed in parts of the stands with high natural *** damaged trees suffered 1.33–1.90 wounds that were inflicted up to a height of 1 m above ground *** all sites mean wound sizes were large,89–1190 cm2,and caused elevated risk of future fungal *** damage caused by skidding during timber harvesting can be minimized by better planning the harvest operations,and training forest workers in reduced impact logging.

关键词： Residual tree damage Beech Skidding trails Wood harvesting Greece

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Liver transplantation and non-alcoholic fatty liver disease

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World Journal of Gastroenterology 2014年第42期20卷 15532-15538页

作者： petros Zezos Eberhard L Renner Liver Transplant Program/Multi-Organ Transplant Program University Health Network/Toronto General Hospital University of Toronto

Non-alcoholic fatty liver disease(NAFLD) is an important health problem worldwide. NAFLD encompasses a histological spectrum ranging from bland liver steatosis to severe steatohepatitis(nonalcoholic steatohepatitis, NASH) with the potential of progressing to cirrhosis and its associated morbidity and mortality. NAFLD is thought to be the hepatic manifestation of insulin resistance(or the metabolic syndrome); its prevalence is increasing worldwide in parallel with the obesity epidemic. In many developed countries, NAFLD is the most common cause of liver disease and NASH related cirrhosis is currently the third most common indication for liver transplantation. NASH related cirrhosis is anticipated to become the leading indication for liver transplantation within the next one or two decades. In this review, we discuss how liver transplantation is affected by NAFLD, specifically the following:(1) the increasing need for liver transplantation due to NASH;(2) the impact of the increasing prevalence of NAFLD in the general population on the quality of deceased and live donor livers available for transplantation;(3) the long term graft and patient outcomes after liver transplantation forNASH,and finally;and(4)the de novo occurrence of NAFLD/NASH after liver transplantation and its impact on graft and patient outcomes.

关键词： Liver transplantation Non-alcoholic fatty liver disease Hepatic steatosis Steatohepatitis Liver cirrhosis Metabolic syndrome Insulin resistance Obesity

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Inflammatory bowel disease and thromboembolism

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World Journal of Gastroenterology 2014年第38期20卷 13863-13878页

作者： petros Zezos Georgios Kouklakis Fred Saibil Gastrointestinal Endoscopy Unit University General Hospital of AlexandroupolisDemocritus University of Thrace Division of Gastroenterology Department of Medicine Sunnybrook Health Sciences CentreUniversity of Toronto

Patients with inflammatory bowel disease (IBD) have an increased risk of vascular complications. Thromboembolic complications, both venous and arterial, are serious extraintestinal manifestations complicating the course of IBD and can lead to significant morbidity and mortality. Patients with IBD are more prone to thromboembolic complications and IBD per se is a risk factor for thromboembolic disease. Data suggest that thrombosis is a specific feature of IBD that can be involved in both the occurrence of thromboembolic events and the pathogenesis of the disease. The exact etiology for this special association between IBD and thromboembolism is as yet unknown, but it is thought that multiple acquired and inherited factors are interacting and producing the increased tendency for thrombosis in the local intestinal microvasculature, as well as in the systemic circulation. Clinicians’ awareness of the risks, and their ability to promptly diagnose and manage tromboembolic complications are of vital importance. In this review we discuss how thromboembolic disease is related to IBD, specifically focusing on: (1) the epidemiology and clinical features of thromboembolic complications in IBD; (2) the pathophysiology of thrombosis in IBD; and (3) strategies for the prevention and management of thromboembolic complications in IBD patients.

关键词： Inflammatory bowel disease Crohn’ s disease Ulcerative colitis Thrombosis Thromboembolism Hypercoagulability Epidemiology Endothelial dysfunction Treatment

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