Biomechanics of aligned cell sheets for arterial tissue engineering

Cardiovascular disease remains the leading cause of death in the United States and oftentimes damaged or occluded arteries need to be replaced. Current surgical materials are unsuitable for small diameter, high pressure vessels such as the carotid and coronary artery because they cannot match the mechanical properties of native tissue. Compliance mismatch between the two materials leads to complications such as anastomotic intimal hyperplasia, thrombosis, and aneurysm. Therefore there is significant clinical need for a tissue engineered arterial graft suitable for small diameter, high pressure vessels. An artery is composed of three layers, but the middle layer, the tunica media, is responsible for bearing normal physiological loads. The medial layer features alternating layers of smooth muscle cells and extracellular matrix where each layer has smooth muscle cells and collagen aligned helically along the length of the artery. This structural feature coupled with the composition of the extracellular matrix cause arterial tissue to have a non-linear mechanical response. A tissue engineered vascular graft that recapitulates the native arterial structure may overcome the limitations of current tissue engineered strategies. We hypothesize that a tissue engineered arterial graft can be built by stacking aligned, single layer cell sheets to better mimic native mechanical properties. Cell sheets are confluent layer of cells and extracellular matrix. In the first aim of this work we developed an inexpensive, novel force sensor design capable of measuring small forces (< 1 mN) that we incorporated into a custom-built uniaxial tensile tester. For the second aim we developed a technique for culturing single layer, aligned, bovine vascular smooth cell sheets. We accomplished this by developing a technique for grafting N-isopropylacrylamide, a thermo-responsive polymer, onto the surface of flat and micropatterned poly-dimethylsiloxane (PDMS) substrates. These substrates allow cell sheets to be cultured and then be detached by decreasing the temperature. In the third aim we experimentally characterized the mechanical and structural properties of aligned vascular smooth muscle cell sheets to show that cell orientation can be controlled by the micropattern and that cellular alignment leads mechanical anisotropy. We also successfully modeled the cell sheet mechanical behavior using existing phenomenological models. The results from this work suggest that aligned cell sheets are capable of recapturing the non-linear stress-strain response of native arterial tissue, making them suitable for arterial tissue engineering. The results from this work provide an experimental and computational foundation for future efforts towards building a multi-layered cell sheet based arterial tissue

Tekijöiden määrittäminen jotka osoittavat tarpeen tekemään laajempi kiinteistöjen vaikutusten arvioinnin väylähankkeiden yhteydessä

I samband med planering av trafikstråk (järn- och landsvägar) är väghållaren skyldig enligt banlagen (110/2007) och landsvägslag (502/2005) att bedöma verkningar av järnvägs- eller landsvägsprojektet. En av de många utredningar som skall göras, är om inverkan på fastighetsstrukturen. Lagen stadgar inte hur eller i vilken omfattning som utredningarna skall genomföras, det är Trafikverket som gör beslutet om hur utredningen utförs beroende på projektets behov. Det besluts om bedömning av inverkan på fastighetsstrukturen skall utföras i samband med trafikstråksplaneringen eller som en skild och mer omfattande utredning av en expert på fastighetsteknik. Avhandlingens mål är att hitta de faktorer i fastighetstrukturen som indikerar om inverkan på den av ett trafikstråksprojekt kan lindras med fastighetstekniska åtgärder. Faktorerna används sedan för att utveckla ett beslutsunderlag för när Trafikverket skall göra beslutet om utredningen om inverkan på fastighetsstrukturen genomförs i samband med trafikstråksplaneringen eller som en skild utredning. För att definiera faktorerna har en litteraturanalys utförts som fokuserar på att belysa frågor kring fastighetsstrukturen, fastigheternas användning och påverkan på trafiken samt användning av fastighetstekniska åtgärder i samband med trafikstråksprojekt så som ägoreglering och vägreglering. Faktorerna från teorin jämfördes genom en fallstudie av fyra projekt. Projekten var sådana var man har haft möjligheter att använda sig av fastighetstekniska åtgärder för att lindra inverkan på fastighetsstrukturen i samband med trafikstråksprojekt. Fallstudie metoden valdes eftersom det finns få fall inom ämnet att undersöka. Metoden möjliggör noggranna och detaljerade jämförelser för att man använder ett litet fång. Det leder på samma gång till att resultatet är svårt att generalisera och passa in på alla situationer som man kan med kvantitativ data. Genom att undersöka faktorerna som inverkar i litteraturanalysen och fallstudien fann man inte ett enskilt sådant resultat som skulle gå att använda direkt i alla situationer för att definiera om det är en fastighetsstruktur som kan lindras med fastighetstekniska åtgärder. Det resulterade att det framställdes rekommendationer för hur de olika faktorerna skall beaktas beroende på trafikstråksprojekt. Rekommendationerna hjälper att kompletterar och konkretiserar Trafikverkets tidigare beslutskriterier för att beställa en mer omfattande utredning om fastighetsstrukturen.Rata- ja maantiesuunnittelun yhteydessä on ratalain (110/2007) ja maantielain (502/2005) mukaan esitettävä selvitys hankkeen arvioiduista vaikutuksista. Vaikutukset kiinteistörakenteeseen on yksi monista selvityksistä jotka tehdään. Laissa ei määritellä millä tavalla tai laajuudella vaikutukset on selvitettävä. Liikennevirasto päättää selvityksen laajuudesta selvitettävän hankkeen tarpeiden mukaan. Selvitys kiinteistörakenteesta tehdään joko väyläsuunnittelun yhteydessä tai erillisenä ja laajempana kiinteistöteknisen asiantuntijan tekemänä selvityksenä. Tutkielman tarkoituksena on löytää kiinteistörakenteesta ne tekijät, jotka osoittavat voidaanko väylähankkeen vaikutuksia kiinteistörakenteeseen vähentää kiinteistöteknisillä toimenpiteillä. Näiden tekijöiden avulla tutkimuksessa on kehitetty perusteet joidenka avulla Liikennevirastossa voidaan tehdä päätös siitä tehdäänkö selvitys kiinteistörakenteen vaikutuksesta väyläsuunnitellun yhteydessä vai asiantuntija-arviona. Kirjallisuustutkimuksessa keskityttiin selvittämään kiinteistörakenteeseen vaikuttavia tekijöitä, kuten kiinteistöjen käyttöä ja vaikutusta liikenteeseen sekä kiinteistöteknisinä toimenpiteinä käytettyjä tilus- ja tiejärjestelyjä liikenneväylähankkeissa. Teorioita verrattiin tapaustutkimukseen jossa kohteena oli neljä erilaista liikenneväylähanketta joissa oli mahdollisuus käyttää kiinteistöteknisiä toimenpiteitä. Tapaustutkimusmenetelmä valittiin, koska aihealueesta ei ole riittävästi aineistoa olemassa. Tapaustutkimus on metodi missä on mahdollista tutkia pieni määrä tapauksia syvällisesti ja tarkasti mutta tuloksia on vaikea yleistää samalla tavalla kun kvantitatiivisissa tutkimuksissa. Kirjallisuus- ja tapaustutkimuksen vertailu ei tuottanut yksittäistä määrittävää tekijää jota voitaisiin käyttää kaikissa tilanteissa harkittaessa mahdollisuuksia vähentää kiinteistörakenteen aiheuttamia haittoja kiinteistöteknisillä toimenpiteillä. Lopputuloksena oli suositus niistä tekijöistä jotka on hyvä ottaa huomioon kiinteistörakenteen selvitystarvetta arvioitaessa. Suosituksella voidaan täydentää ja selventää Liikenneviraston aikaisempaa päätöksentekokriteeriä jota on käytetty päättäessä kuinka laajasti selvitys kiinteistörakenteesta pitäisi tehdä.When planning routes (highways and railways) you are required by law (Ratalaki (110/2007) and Maantielaki (502/2005)) to assess through different surveys the impact of the route. One of many surveys that should be done is about the impacts on the cadastral structure. The law doesn’t stipulate in what way or how vast the different surveys should be made, it’s the Finnish Transport Agency that makes the decision according to the project’s needs. They decide if the survey about the impact on the cadastral structure should be done in the route plan or as a separate and more extensive survey done by an expert on cadastral matters. The purpose of this thesis is to determine the different factors which show if the impacts on the cadastral structure caused by the route project can be reduced by using cadastral technical proce-ures. The factors will later be used to develop the Finnish Transport Agency’s decision making on whether to do a survey in the route plan or as a more comprehensive version. A literature analysis was conducted to determine which factors are important to the cadastral structure, the different types of cadasters traffic needs and the use of cadastral technical procedures like road and land consolidation in route projects. The factors where later on compared to four case studies. The cases all included the opportunity to use cadastral technical measures to reduce the impact of route projects. The Case study research method gives you an opportunity to study cases thoroughly and is suitable where there isn’t that many projects that have been done. The problem with the method is that you can’t make generalizations from the result as easily you could do with a quantitative method. By comparing the results from the literature analysis and the case studies the conclusion was that there was not a single factor that could be used in all circumstances to determine the suitability for cadastral technical procedures. However, it resulted in a recommendation for how the different factors should be accounted for depending on the route projects. The recommendations help the decision making by supplementing and clarifying the Finnish Transport Agency’s criteria for ordering a more extensive survey about the cadastral structure

Silk-fibronectin protein alloy fibres support cell adhesion and viability as a high strength, matrix fibre analogue

Silk is a natural polymer with broad utility in biomedical applications because it exhibits general biocompatibility and high tensile material properties. While mechanical integrity is important for most biomaterial applications, proper function and integration also requires biomaterial incorporation into complex surrounding tissues for many physiologically relevant processes such as wound healing. In this study, we spin silk fibroin into a protein alloy fibre with whole fibronectin using wet spinning approaches in order to synergize their respective strength and cell interaction capabilities. Results demonstrate that silk fibroin alone is a poor adhesive surface for fibroblasts, endothelial cells, and vascular smooth muscle cells in the absence of serum. However, significantly improved cell attachment is observed to silk-fibronectin alloy fibres without serum present while not compromising the fibres' mechanical integrity. Additionally, cell viability is improved up to six fold on alloy fibres when serum is present while migration and spreading generally increase as well. These findings demonstrate the utility of composite protein alloys as inexpensive and effective means to create durable, biologically active biomaterials.T32 EB006359 - NIBIB NIH HH

Continuous control of an underground loader using deep reinforcement learning

Reinforcement learning control of an underground loader is investigated in simulated environment, using a multi-agent deep neural network approach. At the start of each loading cycle, one agent selects the dig position from a depth camera image of the pile of fragmented rock. A second agent is responsible for continuous control of the vehicle, with the goal of filling the bucket at the selected loading point, while avoiding collisions, getting stuck, or losing ground traction. It relies on motion and force sensors, as well as on camera and lidar. Using a soft actor-critic algorithm the agents learn policies for efficient bucket filling over many subsequent loading cycles, with clear ability to adapt to the changing environment. The best results, on average 75% of the max capacity, are obtained when including a penalty for energy usage in the reward.Comment: 9 pages, 7 figure

Monthlong Intubated Patient with Life-Threatening COVID-19 and Cerebral Microbleeds Suffers Only Mild Cognitive Sequelae at 8-Month Follow-up: A Case Report.

OBJECTIVE: To elaborate on possible cognitive sequelae related to COVID-19, associated cerebrovascular injuries as well as the general consequences from intensive care. COVID-19 is known to have several, serious CNS-related consequences, but neuropsychological studies of severe COVID-19 are still rare. METHODS: M., a 45-year-old man, who survived a severe COVID-19 disease course including Acute Respiratory Distress Syndrome (ARDS), cerebral microbleeds, and 35 days of mechanical ventilation, is described. We elaborate on M's recovery and rehabilitation process from onset to the 8-month follow-up. The cognitive functions were evaluated with a comprehensive screening battery at 4 weeks after extubation and at the 8-month follow-up. RESULTS: Following extubation, M. was delirious, reported visual hallucinations, and had severe sleeping difficulties. At about 3 months after COVID-19 onset, M. showed mild to moderate deficits on tests measuring processing speed, working memory, and attention. At assessments at 8 months, M. performed better, with results above average on tests measuring learning, memory, word fluency, and visuospatial functions. Minor deficits were still found regarding logical reasoning, attention, executive functioning, and processing speed. There were no lingering psychiatric symptoms. While M. had returned to a part-time job, he was not able to resume previous work-tasks. CONCLUSION: This case-study demonstrates possible cognitive deficits after severe COVID-19 and emphasizes the need of a neuropsychological follow-up, with tests sensitive to minor deficits. The main findings of this report provide some support that the long-term prognosis for cognition in severe COVID-19 may be hopeful

Polarised light sheet tomography

The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. 608133 and Scottish Funding Council (SFC) Horizon fund.The various benefits of light sheet microscopy have made it a widely used modality for capturing three- dimensional images. It is mostly used for fluorescence imaging, but recently another technique called Light Sheet Tomography solely relying on scattering was presented. The method was successfully applied to imaging of plant roots in transparent soil, but is limited when it comes to more turbid samples. This study presents a Polarised Light Sheet Tomography system and its advantages when imaging in highly scattering turbid media. The experimental configuration is guided by Monte Carlo Radiation Transfer methods, which model the propagation of a polarised light sheet in the sample. Images of both reflecting and absorbing phantoms in a complex collagenous matrix were acquired, and the results for different polarisation configurations are compared. Focus scanning methods were then used to reduce noise and produce three-dimensional reconstructions of absorbing targets.PostprintPeer reviewe

Lilliput

Catalog for the exhibition Lilliput held at the Seton Hall University Walsh Gallery, June 8 - July 24, 2009. Curated by Jeanne Brasile and Asha Ganpat. Includes an essay by Jeanne Brasile and Asha Ganpat. Includes color illustrations

Network Analysis of Intrinsic Functional Brain Connectivity in Alzheimer's Disease

Functional brain networks detected in task-free (“resting-state”) functional magnetic resonance imaging (fMRI) have a small-world architecture that reflects a robust functional organization of the brain. Here, we examined whether this functional organization is disrupted in Alzheimer's disease (AD). Task-free fMRI data from 21 AD subjects and 18 age-matched controls were obtained. Wavelet analysis was applied to the fMRI data to compute frequency-dependent correlation matrices. Correlation matrices were thresholded to create 90-node undirected-graphs of functional brain networks. Small-world metrics (characteristic path length and clustering coefficient) were computed using graph analytical methods. In the low frequency interval 0.01 to 0.05 Hz, functional brain networks in controls showed small-world organization of brain activity, characterized by a high clustering coefficient and a low characteristic path length. In contrast, functional brain networks in AD showed loss of small-world properties, characterized by a significantly lower clustering coefficient (p<0.01), indicative of disrupted local connectivity. Clustering coefficients for the left and right hippocampus were significantly lower (p<0.01) in the AD group compared to the control group. Furthermore, the clustering coefficient distinguished AD participants from the controls with a sensitivity of 72% and specificity of 78%. Our study provides new evidence that there is disrupted organization of functional brain networks in AD. Small-world metrics can characterize the functional organization of the brain in AD, and our findings further suggest that these network measures may be useful as an imaging-based biomarker to distinguish AD from healthy aging