Florida Üniversitesi&#39;nden bir tohum hibe - College Tıp minnetle kabul edilmektedir. NIH / NIGMS R25 GM061347: bilimsel geliştirme (MBR-RISE) bursu için araştırma girişimi - Lisansüstü (Manuel Salinas) biyomedikal araştırma programları bir azınlık fırsatları ile desteklenmiştir. Florida Uluslararası Üniversitesi ile Wallace H. Coulter Vakfı maddi destek, Biyomedikal Mühendisliği Bölümü de minnetle kabul edilmektedir. Kamau Pier, Malaki Suttle, Kendall Armstrong ve İbrahim Alfonso: Son olarak, yazarlar deneysel sürecinin çeşitli aşamalarında onların yardım için aşağıdaki öğrencilerimize teşekkür.

1. Hazırlık <ol><li> Tasarım ve tri-broşür valf geometri karşılamak için bir montaj imal. Bu en azından kapakçık dikiş-in için bir vana tutucu ve darbe teksir sistem üzerine düzeneğini sabitlemek için valf tutucu ve çevresindeki aksesuarlar ev için bir tüp içerir. Bizim durumumuzda, biz ViVitro Labs Inc (Victoria, BC) edinilebilir bir ticari darbe teksir sistemi kullanılmaktadır. Vana sahibi tasarım hem de öncesi ve sonrası montaj konfigürasyonları Şekil 1&#39;de gösterilmiştir. </li><li> Tüm döngü önce kullanım astarlanmalıdır gerekir. Bu iki adımdan oluşur: i) kullanmadan önce herhangi bir bozulmuş boruların değiştirilmesi ve ii) döngü bağlı araçlar kalibrasyon, yani pompa kullanılan, akış probu dahil olmak üzere sabun çözeltisi ve su kullanarak tüm döngü sistemin temizlik ve basınç dönüştürücüler (genellikle atriyal, aort ve ventriküler yerlerde ölçülen). Kalibrasyon init olabilirially% 1 tuz çözeltisi kullanılarak gerçekleştirilebilir ve önceden kan analog gliserin çözeltisi kullanılarak tekrar edilmelidir. </li></ol> 2. Yerli Aort Kapak Diseksiyon <ol><li> Bir USDA onaylı mezbaha (Kurumsal Hayvan Bakım ve Kullanım Kurulu (IACUC) onayı gerekli olabilir) sağlam aorta ile 4 taze domuz kalpleri edinin. Bizim durumumuzda, bizim diseksiyon protokol Florida International University (: 11-020 Protokol Onay Numarası) de IACUC tarafından onaylanmıştır. Deiyonize su ile kalp durulayın ve hidrodinamik test laboratuvara buz üzerinde serum fizyolojik (PBS) çözümü ve ulaşım tamponlu% 1 antibiyotik / antimikotik ve steril fosfat ile dolu bir kap yerleştirin. </li><li> Bir diseksiyon tavada kalpleri yerleştirin ve dikkatli bir şekilde perikard çıkarın. Ventral yüzü size bakacak şekilde kalp yerleştirin. Görme incelemek ve kalbin dört odaları belirlemek ve sağlam aort üzerindeki arkus bulun. </li><li> Tw içine kalp ayırıno halka altında yaklaşık 0.75 yatay olarak kesen tarafından yarıya, aort ve sol ventrikül arasındaki birleşme yani. Dikkatle hala sol ventrikül doku kademeli bağlanmış sağlam aort izole edin. </li><li> Herhangi bir hasar ya da kalsifikasyon herhangi bir işaret var sağlamak aort kökü, aort ve alt halka arasındaki bölgede, bulunan aort kapak inceleyin. </li><li> Halka yukarıda ~ 1 aort bölünmüş ve aort kapak (Şekil 2a) izole etmek için halka aşağıdaki sol ventrikül doku segmentinde ayrı. </li></ol> 3. Polimer ve Yerli Vana dikilmesi Süreci <ol><li> Her bir valf baz sonrası yuvasının taban ile aynı hizaya gelecek şekilde, valf yuvasındaki kalp kapak yerleştirin. Bir ataş ile geçici olarak her yazının yerinde vana Güvenli, ama commissures veya başlangıç ​​çizgileri zarar vermemeye dikkat edin. </li><li> Içinde dikiş takıniğne. Dışarıdan iğnesi kolayca altından çekilmiş olabilir içinde bu tür için, ilk delik içinden geçen iğne tarafından valf tutucusunun alt dikiş başlayın. Bir döngü şekilde, dikey olarak vana sahibinin mesajları kadar vana dikiş başlar. </li><li> Tutucu ve tutucu mesajların ipuçları etrafında ek sütür ile güvenli çevresi boyunca dikiş (Şekil 2b) ile ilerleme. Valf tamamen 3 mesaj ve valf yuvasını (Şekil 2D ve 2E) ve çevresinin sütür kullanılarak sabitlenir kağıt klip (Şekil 2c) çıkartılabilir. </li></ol> 4. Hidrodinamik Değerlendirme Not: Gerçek kullanılan protokole özgü darbe teksir sistemine bağlı olarak değişir. Burada verilen tüm bilgiler ViVitro Darbe teksir Sysytem (ViVitro Labs, Inc, Vancouver, BC) kullanılır caontained. <ol><li> Bi-broşür vaLve <ol><li> 70 atım / dk &#39;ya darbe teksir sisteminin kalp hızı ayarlayın. </li><li> Pompa (ViVitro sistemi durumunda S35 dalga biçimi hidrodinamik tüm testler için seçildi) sürmek için bir akış dalga seçin. Deneylerde kullanılan belirli bir dalga biçimi Lim ve ark. (2001), 17 ile gösterilmiştir. </li><li> Amplifikatör ve pistonlu pompa açın. 15 dakika kadar sıcak. </li><li> Aort pozisyonda yer bi-broşür vanası (Şekil 2f). </li><li> Sızıntıları oluşabilir cihazın tüm kavşak üzerinde smear vakum gres. </li><li> Atriyal bölmesinde gliserin / tuzlu sıvı dökün. % 35 / 0.7 L gliserin ve tuzlu su çözeltisi% 65 / 1.3 L: pulsatil çoğaltıcı sistemi ile sıvı 2 L çalışır unutmayın. Tuzlu su çözeltisi 9 konsantrasyonunda iyonu giderilmiş su içinde iyi çözündürüldü tuzu kullanılarak hazırlanır mg / mL (ağırlık / hacim). </li><li> Aort konumda olan akış dönüştürücü açın. </li><li> Inci kalibree pompası. </li><li> Basınç transdüseri ile takip akış transdüseri kalibrasyon ile devam edin. Benzer şekilde pompaya, sadece kalibre sekmesi altında her akış ve basınç için ViVitest yazılım (ViVitro Labs Inc) tarafından verilen talimatları izleyin. </li><li> Kalibrasyon işlemi tamamlandıktan sonra sıvı aort bölmesi doldurur kadar, düşük devirde pompa başlar. Sızıntı olup olmadığını kontrol edin. Ek vakum gres gerekirse kullanın. </li><li> Iki stop-musluklar (aort ve ventriküler dönüştürücüler) açık konuma getirin. </li><li> Atım hacmi 80 ml / yendi ulaşana kadar pompanın devir artırın. </li><li> Akış stabilize kadar sistem 10 dakika çalıştırmak için izin verir. Akış istikrar dalga ekranda görüntülenen akış ve basınç gözlemleyerek doğrulanabilir. Döngüleri arasındaki Düşük hiçbiri değişim sistemi istikrar iyi bir göstergedir. </li><li> ViVitest yazılımında modu elde seçin. </li><li> 10 döngü toplamak tıklayın. </li><li> Analiz modu, cmasaya yalamak ve dosyayı kaydedin. Ayrıca ViVitest olarak fotoğraf ek bileşenini seçeneğini kullanarak dalga bir görüntü kaydedin. </li></ol></li><li> Yerli ve Polimer vanalar <ol><li> 3.1.3 bi-broşür valf talimatlardan - polimer ve hayvan vanalar için, aynı adımları 3.1.1 izleyin. </li><li> Özel yapılmış aksamından cam tüp içindeki dikildi valf ile vana tutucu yerleştirin. Üst ve alt parçaları ve yan vida ve somun ile yerinde güvenli ile sandviç tüp. </li><li> Aort odası ve orijinal aort kapak tutucu tarihleri ​​arasında montaj. </li><li> 3.1.16 bi-broşür valf talimatlardan - adım 3.1.5 ile devam edin. </li></ol></li></ol> 5. İşleme sonrası <ol><li> Akış ve Basınç Dalga Şekilleri <ol><li> Ortalama dalga toplanan, yani aort basıncı (AP), ventriküler basınç (VP) ve debi (Q) her biri için toplanan veriler. </li><li> Her vana grubunun (polimer, domuz native aort kapak ve iki-broşür), ilgili AP, Başkan Yardımcısı ve Q karşı aynı arsa üzerinde zaman ilişkiler arsa. </li><li> AP, normal, doğal aort kapak 18 ve doğrulama amacıyla literatürden bi-broşür protez kapak 19 araziler üst üste. </li></ol></li><li> Hidrodinamik ölçümleri <ol><li> Test edilen her vana için, aşağıdaki hidrodinamik ölçümleri hesap edilmelidir: a) İleri akış basınç düşüşü ve maksimum transvalvüler basınç (TVP), b) aort kökü aort ileri akım, kapanış, kaçak kare (RMS) ileri akış hızı, c) ortalama ve toplam yetersizlik hacmi, d) valf orifis alanı (EOA), e) transaortik ileri akışı, kapanış, kaçak ve toplam enerji kayıpları. <ol><li> İleri akış basınç düşüşü TVP okumalarından hesaplanır ve 3 zaman aralıkları, P olarak kategorize edilebilir: ileri akışı ve H aralığı: aralığı 0 TVP ile başlayan ve 0 akışı ile biten 0 TVP, F ile başlar ve biter aralığı. Maksimum TVP maximum basınç farkı aort ve ventriküler basınç okumalarından vana karşısında kaydetti. </li><li> RMS ileri debisi (Q rms) aşağıdaki gibi ileri debi büyüklüğü ölçülmesi için yararlı bir metrik sağlar: <img alt="Denklem 1" fo:src="/files/ftp_upload/50335/50335eq1highres.jpg" src="/files/ftp_upload/50335/50335eq1.jpg" /> &#39;N&#39; zaman noktalarının sayısı olduğu için &#39;i&#39; toplanan anlık sarfiyat ölçümü olan &#39;Q i&#39;, topladı. </li><li> Ileri aort, kapanış ve kaçak hacmi İleri aşağıdaki zaman aralıklarında, temel hesaplanır: ileri akışı (t 1) sonuna kadar vana (t o), ileri akış başında; Kapanış: t 1 örneği kadar kapak kapama (t 2) &#39;; Kaçak: t 2 kalp döngüsü (t 3) sonuna kadar. Toplam yetersizlik hacmi sadece clos toplamıdıring ve kaçak hacmi. </li><li> Kan özelliklerine göre EOA 20 gibi söz konusu dönemlerin her sırasında ortalama JP gelen 3 aralıklarla, P, F ve H için hesaplanan: <img alt="Denklem 1" fo:src="/files/ftp_upload/50335/50335eq2highres.jpg" src="/files/ftp_upload/50335/50335eq2.jpg" /></li><li> Enerji kayıpları aşağıdaki tabloda gösterildiği 21 olarak tanımlanır: <img alt="Denklem 1" fo:src="/files/ftp_upload/50335/50335eq3highres.jpg" src="/files/ftp_upload/50335/50335eq3.jpg" /></li></ol></li></ol></li></ol>

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Yazarlar ifşa hiçbir şey yok.

Bu çalışmada, bir polimer ve doğal domuz valf bu hidrodinamik test gerçekleştirilir, böylece üç yaprakçık valf geometrileri karşılamak için ticari olarak satılan bir pulsatil teksir biriminin modifiye yarar göstermiştir. Özellikle bizim durumumuzda, sistem modifiye bir ViVitro sol kalp ve ViViTest veri toplama sistemi (ViVitro Systems, Inc, Victoria, BC, Kanada) ile kontrol sistemik simülatörü sistemi (Şekil 1a) oldu. Ancak, sistem tüm insan dolaşımı 22-25 için öne...

Kalp kapak hastalığı genellikle dejeneratif kapak kalsifikasyonu 1, romatizmal ateş 2, endokardit 3,4 veya konjenital doğum kusurları kaynaklanır. Kapak hasarı darlığı ve / veya yetersizliği kapak prolapsusu ve cerrahi tamir edilemez neden oluştuğunda, doğal kapak genellikle protez kapak ile değiştirilir. Şu anda mevcut seçenekleri mekanik vanalar (kafes-vanaları, devirme disk vanalar, vb.), Homogreft ve biyolojik kapakların (domuz ve sığır vanalar) içerir. Mekanik vanalar genellikle dayanıklılık dayalı genç hastalar için tavsiye edilir, ancak hastanın trombotik komplikasyonlar 5 önlemek için antikoagülan tedavisi olmaya devam etmelidir. Homogreft ve biyolojik protez kan inceltici tedavi önlemek için etkin seçimler olmuştur, ancak bu vanalar fibrozis için yüksek risk, kalsifikasyon, dejenerasyon, ve valf arızası 6 yol açan immünojenik komplikasyonlar. Doku mühendisliği vanaları gelişmekte olan bir teknoloji 7-9 olarak araştırıldı, ama çok hala ortaya gerekmektedir edilmektedir. Alternatif dayanıklı, biyo-uyumlu, protez kalp kapak hastalığı hastaların yaşam kalitesini artırmak için ihtiyaç vardır. Yine, bu valf tasarımı kalp hastalığı kapak 10 ile seçilen hastaların tedavisinde dönüştürülmesi için potansiyel gösteren transkateter yaklaşımlarla transkateter valf teknolojisi kullanılan biyoprotez yerini alabilir. Gibi mevcut standartlara belirttiği, başarılı bir kalp kapağı yerine aşağıdaki performans özelliklere sahip olmalıdır: &quot;1) kabul edilebilir küçük ortalama basınç farkı düşüşü ile akış ileri sağlar; 2) kabul edilebilir küçük yetersizliği olan retrograd akışını engeller, 3) embolizasyon direnir;) 4 direnir hemoliz, 5) trombüs oluşumuna karşı dayanıklıdır; 6) biyouyumlu, 7) in vivo tanı teknikleri ile uyumludur; 8) hedef teslim ve implante edilebilir birnüfus, 10) kabul edilebilir bir gürültü seviyesi vardır;, 9) kez yer sabit kalır 11) tekrarlanabilir fonksiyonu vardır; 12), makul bir ömür boyu işlevselliğini tutar genel sınıf ile uyumlu, 13) makul bir raf için işlevselliği ve kısırlık korur implantasyon öncesinde hayat. &quot;11. Mevcut kapak protezi eksikliklerin bazıları potansiyel bir polimer vana ile üstesinden olabilir. Biyouyumlu polimerler biyo, anti-hidroliz, anti-oksidasyon ve gibi avantajlı mekanik özelliklerine göre üst aday olarak kabul edilmiştir , yüksek mukavemetli ve viskoelastisite. Özellikle, elastomerik polimerler Elastomerler yumuşak doku özelliklerini taklit etmek için uygun olabilir. doğal kapak dinamikleri benzeyen malzeme deformasyon sağlayabilir, ve biyo-hoşgörülü ve birleştirilmiş dayanabilir mevcut tek yapay malzemeler olabilir in vivo olarak, akışkan ile indüklenen, bükülme ve gerilme, ancak sağlıklı, benzer bir şekilde hareketdoğal kapak hareket. Ayrıca, elastomer seri üretim kolaylıkla saklanan boyutlarda, çeşitli, maliyet-etkin cihazlar olması bekleniyor ve yapısal lifli takviye ile artar olabilir olabilir. Bir tri-broşür kapak monte polimer malzemelerin kullanımı kavramı yeni bir şey değil ve sınırlı kapak dayanıklılığı nedeniyle büyük ölçüde terk edildi, son 50 yılda 12 üzerinde çeşitli araştırma soruşturma konusu olmuştur. Ancak, yeni üretim yöntemleri 13,14 gelişine, polimer malzemelerin 15,16 ve transkateter valf teknolojisi ile polimer kapak yerine potansiyel kesintisiz entegrasyon takviye, son bir potansiyel olarak polimer vanalar gelişmekte olan yenilenmiş bir ilgi ve faaliyet olmuştur mevcut ticari vanaları için alternatif. Bu açıdan, hidrodinamik işlevselliğini değerlendirmek için bu vanalar test etkinleştirmek için bir protokol ilk adımdırdeğerlendirme sürecinde; henüz ticari darbe simülatörü sistemleri genellikle üç-broşür kapak tasarımları karşılamak için donatılmıştır ve ticari kalp kapakçıkları (örneğin devirme disk, iki broşür mekanik kalp kapakçığı) eklemek için dairesel bir boşluk içermez. İkinci olarak, polimer vanalar olan hidrodinamik sadece göreceli bir bağlamda değerlendirilebilir gelişmekte olan bir teknolojidir. Doğal kalp kapak basınç ve akış veri mevcut olmasına rağmen, bunun için hesap şekilde polimer vanalar değerlendirmek için kullanılan aynı pulsatil simülatörü kullanarak, insan vanalar için biyolojik olarak benzer yerli aort domuz vanalar, test yapmak için önemlidir sistem bağlı olabilir ölçüm farklılıkları. Bu nedenle, bu çalışmanın amacı, piyasada bulunan darbe simülatörü tri-broşür kapak yapıları karşılamak için ve sistematik bir göreceli devam polimer kapak hidrodinamik ölçümleri değerlendirmek için bir montaj ile donatılmış nasıl göstermektidahili mekanik ve doğal domuz kalp kapak meslektaşları ile karşılaştırıldığında. Bizim durumumuzda, yeni üç-broşür silikon polimer vanalar önce polimer valf grubu oluşan Florida 13 Üniversitesi&#39;nde geliştirdi.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Pump</td>
			<td>ViVitro Labs</td>
			<td></td>
			<td><a href="http://vivitrolabs.com/products/superpump/" target="_blank">http://vivitrolabs.com/products/superpump/</a></td>
		</tr>
		<tr>
			<td>Flow Meter and Probe</td>
			<td>Carolina Medical</td>
			<td>Model 501D</td>
			<td><a href="http://www.carolinamedicalelectronics.com/documents/FM501.pdf" target="_blank">http://www.carolinamedicalelectronics.com/documents/FM501.pdf</a></td>
		</tr>
		<tr>
			<td>Pressure Transducer</td>
			<td>ViVitro Labs</td>
			<td>HCM018</td>
			<td></td>
		</tr>
		<tr>
			<td>ViVitro Pressure Measuring Assembly</td>
			<td>ViVitro Labs</td>
			<td>6186</td>
			<td></td>
		</tr>
		<tr>
			<td>Valve holder</td>
			<td>WB Engineering</td>
			<td></td>
			<td>Designed by Florida International University. Manufactured by WB Engineering</td>
		</tr>
		<tr>
			<td>Pulse Duplicator</td>
			<td>ViVitro Labs</td>
			<td>PD2010</td>
			<td><a href="http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf" target="_blank">http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf</a></td>
		</tr>
		<tr>
			<td>Pulse Duplicator Data Acquisition and Control System, including ViViTest Software</td>
			<td>ViVitro Labs</td>
			<td>PDA2010</td>
			<td><a href="http://vivitrolabs.com/products/software-daq" target="_blank">http://vivitrolabs.com/products/software-daq</a></td>
		</tr>
		<tr>
			<td>Porcine Hearts and Native Aortic Valves</td>
			<td>Mary&#39;s Ranch Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bi-leaflet Mechanical Valves</td>
			<td>Saint Jude Medical</td>
			<td></td>
			<td><a href="http://www.sjm.com/" target="_blank">http://www.sjm.com/</a></td>
		</tr>
		<tr>
			<td>High Vacuum Grease</td>
			<td>Dow Corning Corporation</td>
			<td></td>
			<td><a href="http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf" target="_blank">http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf</a></td>
		</tr>
		<tr>
			<td>Glycerin</td>
			<td>McMaster-Carr</td>
			<td>3190K293</td>
			<td>99% Natural 5 gal</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Fisher Scientific</td>
			<td>MT21031CV</td>
			<td>100 ml/heart</td>
		</tr>
		<tr>
			<td>Antimycotic/Antibiotic Solution</td>
			<td>Fisher Scientific</td>
			<td>SV3007901</td>
			<td>1 ml in 100 ml of PBS/heart; 20 ml for ViVitro System</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S3014-500G</td>
			<td>9 g/L of deionized water</td>
		</tr>
		<tr>
			<td>Deionized Water</td>
			<td>EMD Millipore Chemicals</td>
			<td></td>
			<td>Millipore Deionized Purification System. 1.3 L for ViVitro System, 200 ml for heart valve dissection process</td>
		</tr>
	</tbody>
</table>

protocol for relative hydrodynamic assessment of tri-leaflet polymer valves

Mevcut protez, xenografts ve homogreftler sınırlamaları üç-broşür polimer kapak protezi alanında gelişmeler son dirilişi yol açmıştır. Ancak, polimer kapak hidrodinamik işlevsellik ilk değerlendirme için bir protokol belirlenmesi tasarım sürecinin erken aşamalarında çok önemlidir. In vitro darbe teksir sistemlerinde Geleneksel esnek tri-broşür malzemeleri karşılamak için yapılandırılmamış, buna ek olarak, polimer kapak işlevsellik değerlendirmesi aynı test koşullarında yerli ve protez kalp kapakçığı için göreli bir bağlamda yapılması gereken o kadar farklı gelen ölçümlerde değişkenlik araçlar önlenebilir. Buna göre,)) yerel (n = 4, ortalama çapı, D = 20 mm), ii) iki-broşür mekanik (n = 2, K = 23 mm) ve III I hidrodinamik değerlendirmesi yapılmıştır polimer kapaklar (n = 5, D, bir ticari olarak temin edilebilen darbe teksir sisteminin kullanımı ile = 22 mm) (ViVitro LabsA.Ş., Victoria, BC) bu üç-broşür kapak geometrileri karşılamak için güncellenmiştir. Florida Üniversitesi&#39;nde geliştirilen Tri-broşür silikon vanalar polimer valf grubunu oluşturdu. Su 35:65 gliserin oranındaki bir karışımı, kan fiziksel özelliklerini taklit etmek için kullanıldı. Basınç ventriküler ve aort pozisyonlarda olurken, anlık akış hızı, sol ventrikül ve aort birimlerinin arayüz ölçülmüştür. Bi-broşür ve literatür doğal kapak veri akışı ve basınç okumaları doğrulamak için kullanıldı. Aşağıdaki hidrodinamik ölçümler bildirilmiştir: ileri akış basınç düşüşü, aort kökü kare ileri akış hızı, aort kapanış, kaçak ve yetersizlik hacmi, transaortik kapanış, kaçak ve toplam enerji kayıpları anlamına gelir. Temsilcisi sonuçları üç valf grupları hidrodinamik ölçümleri başarılı bir ticari darbe teksir sistemi ve subsequentl bir özel yapılmış montaj dahil ederek elde edilebileceğini belirttiy, objektif polimer kapak tasarımı fonksiyonel yönleri üzerinde anlayış sağlamak göre.

Örnek akış ve basınç dalga Şekiller 3, 4 ve 5&#39;te gösterilmektedir. Araziler oldu her grup, için test vanaların örneklem büyüklüğü üzerinden ortalama edildi, n sırasıyla = 5, 4, ve polimer, yerli domuz ve iki broşür gruplar için 2 vana,. Ortalama hidrodinamik ölçümler ve bu örnek boyutları için ortalamanın standart hatası Tablo 1 &#39;de sunulmaktadır. <img alt="Şekil 1" ...

Watch this Scientific Journal Video about Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves at JoVE.com

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

Polimer vanalar gelişmekte olan ilgi yenilendi. Burada, hedefleri üç-broşür geometrileri karşılamak için ve yakın-aynı koşullar altında toplanan yerli ve protez kapak verilerine göre polimer kapak hidrodinamik veri sunmak için bir protokol tanımlamak için ticari bir darbe teksir değiştirme fizibilite göstermek için vardır.

Tri-broşür Polimer Vanalar göreceli hidrodinamik Değerlendirme Protokolü

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of ...

protocol-for-relative-hydrodynamic-assessment-tri-leaflet-polymer

Research

JoVE Journal

Bioengineering

13.7K Görüntüleme.  Florida International University. Polimer vanalar gelişmekte olan ilgi yenilendi. Burada, hedefleri üç-broşür geometrileri karşılamak için ve yakın-aynı koşullar altında toplanan yerli ve protez kapak verilerine göre polimer kapak hidrodinamik veri sunmak için bir protokol tanımlamak için ticari bir darbe teksir değiştirme fizibilite göstermek için vardır.

Video: Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

A Microfluidic-based Hydrodynamic Trap for Single Particles

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in concentrated or crowded particle suspensions, which is difficult using alternative force field-based trapping methods. The hydrodynamic trap is user-friendly, straightforward to implement and may be added to existing microfluidic devices to facilitate trapping and long-time analysis of particles. Overall, the hydrodynamic trap is a new platform for confinement, micromanipulation, and observation of particles without surface immobilization and eliminates the need for potentially perturbative optical, magnetic, and electric fields in the free-solution trapping of small particles.

In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.

Tek Parçacıklar için mikroakışkan tabanlı Hidrodinamik Tuzak

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science.  Methods for ...

Biyomühendislik

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

Devirli Basınç Biyoreaktör Tasarım Ex vivo</emAort Kalp Vanalar> Eğitim

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures can act as a nidus for infection and in many procedures are unable to effect wound repair or interfere with functional tissue regeneration.1 Surgical glues and adhesives, such as those based on fibrin and cyanoacrylates, have been developed as alternatives to sutures for the repair of such wounds. However, current commercial adhesives also have significant disadvantages, ranging from viral and prion transfer and a lack of repair strength as with the fibrin glues, to tissue toxicity and a lack of biocompatibility for the cyanoacrylate based adhesives. Furthermore, currently available surgical adhesives tend to be gel-based and can have extended curing times which limit their application.2 Similarly, the use of UV lasers to facilitate cross-linking mechanisms in protein-based or albumin 'solders' can lead to DNA damage while laser tissue welding (LTW) predisposes thermal damage to tissues.3 Despite their disadvantages, adhesives and LTW have captured approximately 30% of the wound closure market reported to be in excess of US $5 billion per annum, a significant testament to the need for sutureless technology.4
In the pursuit of sutureless technology we have utilized chitosan as a biomaterial for the development of a flexible, thin film, laser-activated surgical adhesive termed 'SurgiLux'. This novel bioadhesive uses a unique combination of biomaterials and photonics that are FDA approved and successfully used in a variety of biomedical applications and products. SurgiLux overcomes all the disadvantages associated with sutures and current surgical adhesives (see Table 1).
In this presentation we report the relatively simple protocol for the fabrication of SurgiLux and demonstrate its laser activation and tissue weld strength. SurgiLux films adhere to collagenous tissue without chemical modification such as cross-linking and through irradiation using a comparatively low-powered (120 mW) infrared laser instead of UV light. Chitosan films have a natural but weak adhesive attraction to collagen (~3 KPa), laser activation of the chitosan based SurgiLux films emphasizes the strength of this adhesion through polymer chain interactions as a consequence of transient thermal expansion.5 Without this 'activation' process, SurgiLux films are readily removed.6-9 SurgiLux has been tested both in vitro and in vivo on a variety of tissues including nerve, intestine, dura mater and cornea. In all cases it demonstrated good biocompatibility and negligible thermal damage as a consequence of irradiation.6-10

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, &#039;SurgiLux&#039;: Preparation and Demonstration

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

Bir Kitosan Bazlı, Lazer Aktif İnce Film Cerrahi Yapıştırıcı, &#39;SurgiLux&#39;: Hazırlık ve Gösteri

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures ...

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.

Biyomalzemelerin Yüksek Verimli Discovery için Polimer Mikroarray&#39;ler

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

Için Mekanik-adaptif Polimer Nanokompozitler bir çevre kontrollü Mikrogerilim Test<em&gt; Ex vivo</em&gt; Karakterizasyonu

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

Intra-lymph Node Injection of Biodegradable Polymer Particles

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these foreign molecules to T and B lymphocytes. Lymph nodes have thus become critical targets for new vaccines and immunotherapies. A recent strategy for targeting these tissues is direct lymph node injection of soluble vaccine components, and clinical trials involving this technique have been promising. Several biomaterial strategies have also been investigated to improve lymph node targeting, for example, tuning particle size for optimal drainage of biomaterial vaccine particles. In this paper we present a new method that combines direct lymph node injection with biodegradable polymer particles that can be laden with antigen, adjuvant, or other vaccine components. In this method polymeric microparticles or nanoparticles are synthesized by a modified double emulsion protocol incorporating lipid stabilizers. Particle properties (e.g.&#160;size, cargo loading) are confirmed by laser diffraction and fluorescent microscopy, respectively. Mouse lymph nodes are then identified by peripheral injection of a nontoxic tracer dye that allows visualization of the target injection site and subsequent deposition of polymer particles in lymph nodes. This technique allows direct control over the doses and combinations of biomaterials and vaccine components delivered to lymph nodes and could be harnessed in the development of new biomaterial-based vaccines.

Lymph nodes are the immunological tissues that orchestrate immune response and are a critical target for vaccines. Biomaterials have been employed to better target lymph nodes and to control delivery of antigens or adjuvants. This paper describes a technique combining these ideas to inject biocompatible polymer particles into lymph nodes.

Biyobozunur Polimer Parçacıklarının Lenf İçi Düğüm Enjeksiyonu

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these ...

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.
Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.
The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites.

Binder Bakteriyel Selüloz kullanmak Sağlam Doğal Elyaf preform üretim

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose ...

Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the molecular, cellular and mechanical mechanisms underlying the maintenance and/or loss of the valvular structure. 
Current models used to study valvular biology include in vitro cultures of valvular endothelial and interstitial cells. Although, in vitro culturing models provide both cellular and molecular mechanisms, the mechanisms involved in the 3D-organization of the valve remain unclear. While in vivo models have provided insight into the molecular mechanisms underlying valvular development, insight into adult valvular biology is still elusive. 
In order to be able to study the regulation of the valvular 3D-organization on tissue, cellular and molecular levels, we have developed the Miniature Tissue Culture System. In this ex vivo flow model the mitral or the aortic valve is cultured in its natural position in the heart. The natural configuration and composition of the leaflet are maintained allowing the most natural response of the valvular cells to stimuli. The valves remain viable and are responsive to changing environmental conditions. This MTCS may provide advantages on studying questions including but not limited to, how does the 3D organization affect valvular biology, what factors affect 3D organization of the valve, and which network of signaling pathways regulates the 3D organization of the valve.

Here, we present an ex vivo flow model in which murine cardiac valves can be cultured allowing the study of the biology of the valve.

Minyatür Doku Kültürü Sistemde Fare Kalp Vanalar Kültürleme

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the ...

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a high-protein crambe meal that has limited value, as it is not fit for food or feed use. However, it contains proteins that could potentially make it a suitable raw material for higher-value products. The purpose of this study was to find methods of making this side stream into extruded films, showing that products with a higher value can be produced. The study mainly considered the development of material compositions and methods of preparing and extruding the material. Wheat gluten was added as a supportive protein matrix material, together with glycerol as a plasticizer and urea as a denaturant. The extrudate was evaluated with respect to mechanical (tensile testing) and oxygen barrier properties, and the extrudate structure was revealed visually and by scanning electron microscopy. A denser, more homogeneous material had a lower oxygen transmission rate, higher strength, and higher extensibility. The most homogeneous films were made at an extruder die temperature of 125-130 &#176;C. It is shown here that a film can be extruded with promising mechanical and oxygen barrier properties, the latter especially after a final compression molding step.

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

The side stream from plant oil production of Crambe abyssinica has limited value. The purpose of this study was to find methods for extruding materials based on this side stream, demonstrating that products with a higher value can be produced. The extrudates were found to have promising properties.

Film Ekstrüzyon<em&gt; Crambe abyssinica</em&gt; / Buğday Gluten Karışımları

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a ...

Synthesis of Functionalized 10-nm Polymer-coated Gold Particles for Endothelium Targeting and Drug Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting and drug delivery are some of the applications of these AuNPs, but endothelial extracellular matrices&#39; defensive properties hamper particle uptake. To address this issue, we describe a synthesis method for ultrasmall gold nanoparticles to improve vascular delivery, with customizable functional groups and polymer lengths for further adjustments. The protocol yields 2.5 nm AuNPs that are capped with tetrakis(hydroxymethyl)phosphonium chloride (THPC). The replacement of THPC with hetero-functional polyethylene glycol (PEG) on the surface of the AuNP increases the hydrodynamic radius to 10.5 nm while providing various functional groups on the surface. The last part of the protocol includes an optional addition of a fluorophore to allow the AuNPs to be visualized under fluorescence to track nanoparticle uptake. Dialysis and lyophilization were used to purify and isolate the AuNPs. These fluorescent nanoparticles can be visualized in both in vitro and in vivo experiments due to the biocompatible PEG coating and fluorescent probes. Additionally, the size range of these nanoparticles render them an ideal candidate for probing the glycocalyx without disrupting normal vasculature function, which may lead to improved delivery and therapeutics.

We describe a method of synthesizing biocompatible 10-nm gold nanoparticles, functionalized by coating poly-ethylene glycol onto the surface. These particles can be used in vitro and in vivo for delivering therapeutics to nanoscale cellular and extracellular spaces that are difficult to access with conventional nanoparticle sizes.

Endotel hedefleme için Functionalized 10-nm polimer kaplı altın parçacıkları ve ilaç dağıtım sentezi

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting ...