Gormsennoer2535

Two Bignoniaceae stems with the distinctive anatomy of a liana are described from the Miocene of South America. They are the first fossil evidence of climbing habit in Bignoniaceae.

The fossil lianas are siliceous permineralizations. Transverse, tangential, and radial thin sections of the woods were prepared for study using standard petrographic techniques and observed under both light and scanning electron microscopy.

The stems consist of wood and presumably bark (peripheral tissues). Selleckchem Ertugliflozin They exhibit phloem wedges, a cambial variant associated with the climbing habit in Bignoniaceae. The wood is diffuse-porous; solitary and in radial multiples vessels; alternated intervessel pitting; ray-vessel pitting with distinct borders; simple perforation plates; rays 1-3 seriate, composed of procumbent cells or body ray cells procumbent with one or two-row of upright or square marginal cells; fibers septate and non-septate, with simple to minutely bordered pits; axial parenchyma scanty paratracheal, vasicentric, sep to understand plant evolution and diversification in South American Andes.Propper assessment of hemodynamic swirling flow patterns, vortices, may help understand the influence of disturbed flow on arterial wall pathophysiology and remodeling. Studies have shown that vortices trigger pathologic cellular changes within the vasculature such as increased inflammation and cellular apoptosis, leading to weakening of the vessel wall indicative of aneurysm development and rupture. Yet many studies qualitatively assess the presence of vortices within the vasculature or assess only their centermost region (critical point analysis) which overlooks the broader characteristics of flow, leading to a narrow view of vortices. This chapter provides a protocol for utilizing commercially available computational fluid dynamic software (ANSYS-FLUENT) to simulate realistic hemodynamic flow patterns, fluid velocity, and wall shear stress in the complex geometry of the cerebral vasculature, as well as an innovative method for assessing flow vortices. This innovative analytic methodology can identify areas of flow vortices and quantify how the broader bulk-flow (opposed to critical point) characteristics change in space and time over the cardiac cycle. Analysis of such flow structures can be used to identify specific characteristics such as vortex stability and the portion of an aneurysmal sac that is dominated by swirling flow, which may be indicative of vascular pathologies.Micropillar arrays are one of the tools that quantify the mechanical forces exerted by endothelial cells and any other adherent cell types. This chapter describes the fabrication and usage of the micropillars that reports spatial distribution of traction forces by endothelial cells. The fabrication begins with making a "master" pillar substrate using photolithography, followed by softlithography of the master with polydimethylsiloxane. The pillars can then be printed with an extracellular matrix protein in specific shape using stamp-off technique. Lastly, imaging of the micropillars with cells and the analysis of the traction force using Matlab-based software are described.In vitro blood-brain barrier (BBB) models have been widely used to simulate in vivo models due to their low cost, feasibility, and repeatability. To serve as a valid substitute, the in vitro BBB should have the similar barrier function as that in vivo. This chapter summarizes the detailed methods for quantifying the barrier function, e.g., the permeability of the BBB to water, ions, and solutes for an in vitro BBB generated on the Transwell filter.Arterial bypass grafts are a standard preclinical model for evaluating physiology and pathophysiology at graft-material interfaces. Implantations of vascular grafts are commonly done as end-to-end grafts in small animal models. Here we detail bilateral end-to-side aortoiliac graft implantation, which requires open surgery and the creation of vascular anastomoses between the graft material and the infrarenal aorta and iliac artery in a nonhuman primate model. In this model, the aortoiliac graft configuration is created using two 4 mm inner diameter vascular grafts (e.g., ePTFE). After exposure and control of the infrarenal aorta and bilateral common iliac arteries and heparinization, the proximal aortic-graft anastomosis is sewn on the lateral wall of the aorta, and subsequently the distal graft-common iliac anastomosis is sewn on the anterior wall of the common iliac artery with one tube graft. Another tube graft is sewn on the contralateral side in the same manner.Conventional ultrasound with frequency (2-15 MHz) has been a global diagnostic and therapeutic tool in clinical medicine, and high-frequency ultrasound (>30 MHz) has been a powerful investigative device for preclinical studies such as cardiovascular research. In this chapter, we describe the use of conventional ultrasound with a 2.5-10 MHz transducer as an investigative device for the measurement/detection of blood flow in rabbit model. The chapter will describe the procedures for the preparation of sonographer, imaging locations, and the details of the rabbits used as well as detailed imaging steps for the preoperative, immediately after operation, and postoperative follow-up ultrasound for vascular surgery, using a vascular graft implantation as an example. We also provide useful notes to avoid pitfalls for successful imaging. The overall goal of this chapter is to deliver the steps in using low-cost, non-invasive, and highly versatile clinical ultrasound imaging in preclinical small animal testing.Preclinical testing in animal model is a required stage of vascular device development. Among small animal models, rabbits provide vasculature with relative larger caliber for anastomotic implantation of vascular grafts as preclinical testing before conducting large animal studies. Rabbits have similar hemostatic mechanism with human and can accommodate vascular grafts with various diameters at different locations, and thus provide a valid model to assess small-diameter vascular grafts. This chapter will describe the procedures and materials required to conduct survival surgery in rabbit carotid artery models for implantation of small-diameter tubular grafts with an end-to-side and end-to-end anastomotic technique.Injectable scaffolds made of biodegradable biomaterials can stabilize a myocardial infarct and promote cardiac repair. Here, we describe an injectable, citrate-containing polyester hydrogel which can release citrate as a cell regulator via hydrogel degradation and simultaneously show sustained release of an encapsulated myeloid-derived growth factor (Mydgf). Xu et al. described the synthesis of hydrogel with biocompatible starting chemicals including citric acid and poly(ethylene glycol) diol. The characterization of materials demonstrated that the developed hydrogels possess tunable degradation and mechanical properties and exhibit sustained drug release. The authors also observed improved postmyocardial infarction (MI) heart repair in a rat MI model through coupling the therapeutic effect of the hydrogel degradation product (citrate) with encapsulated Mydgf. In their study, hematoxylin and eosin (H&E) staining and Masson's trichrome staining were performed on heart samples to evaluate the change in heart structure. Furthermore, immunohistochemistry was used to study neovascularization. Their results showed that the intramyocardial injection of Mydgf-loaded citrate-containing hydrogel significantly reduced scar formation and infarct size, increased wall thickness and neovascularization, and improved heart function.Electrospinning has become a popular polymer processing technique for application in vascular tissue engineering due to its unique capability to fabricate porous vascular grafts with fibrous morphology closely mimicking the natural extracellular matrix (ECMs). However, the inherently small pore sizes of electrospun vascular grafts often inhibit cell infiltration and impede vascular regeneration. Here we describe an effective and controllable method to increase the pore size of electrospun poly(ε-caprolactone) (PCL) vascular graft. With this method, composite grafts are prepared by turning on or off electrospraying of poly(ethylene oxide) (PEO) microparticles during the process of electrospinning PCL fibers. The PEO microparticles are used as a porogen agent and can be subsequently selectively removed to create a porogenic layer within the electrospun PCL grafts. Three types of porogenic PCL grafts were constructed using this method. The porogenic layer was either the inner layer, the middle one, or the outer one.Bypass surgery has proven to be an effective strategy for the treatment of cardiovascular diseases. In this chapter, we describe the preparation of a type of small-diameter vascular grafts with hybrid fibrous structure by co-electrospinning. Of the two components, slow-degrading poly(ε-caprolactone) (PCL) fibers maintain the structural integrity of the graft and provide sufficient mechanical strength. The other component is rapidly degradable polymer polydioxanone (PDS) or type-I collagen that can be used as a carrier to deliver vasoactive molecules at the same time. The in vivo performance of as-prepared vascular grafts was further evaluated in a rat abdominal aorta replacement model.Silk fibroin (SF) is a natural well-known biomaterial that has widely been explored for various tissue engineering applications with great success. Herein, we describe the methodology for fabricating two different types of tubular silk scaffolds aimed for vascular grafting. The first method emphasizes the use of very thin (10-15μm) silk films with unidirectional longitudinal micro-patterns, followed by their sequential rolling, which results in a multilayered tubular graft mimicking native-like cellular composition. The second method describes the fabrication of a bi-layered tubular scaffold comprising of a highly porous inner layer covered with an outer nanofibrous electrospun layer.Blood vessels in the body are multiphasic organs with microenvironmental niches specific to the cells that inhabit each section. Electrospinning is a fabrication technique used to produce nano- to microfibrous architectures capable of mimicking native extracellular matrix structure. Likewise, polycitrate elastomers are favorable luminal materials for vascular applications because of their hemocompatibility and mechanical properties. Here we describe the procedure for fabricating a biphasic polycitrate elastomer, collagen, and elastin electrospun composite to spatially tailor both composition and architecture for recapitulating the intimal and medial layers of the blood vessel in a vascular graft.Tissue-engineered small-diameter vascular grafts are required to match mechanical properties as well as cellular and extracellular architecture of native blood vessels. Although various engineering technologies have been developed, the most reliable strategy highlights the needs for incorporating completely biological components and anisotropic cellular and biomolecular organization into the tissue-engineered vascular graft (TEVG). Based on the antithrombogenic, immunoregulatory, and regenerative properties of human mesenchymal stem cells (hMSCs), this chapter provides a step-by-step protocol for generating a completely biological and anisotropic TEVG that comprises of hMSCs and highly aligned extracellular matrix (ECM) nanofibers. The hMSCs were grown on an aligned nanofibrous ECM scaffold derived from an oriented human dermal fibroblast (hDF) sheet and then wrapped around a temporary mandrel to form a tubular assembly, followed by a maturation process in a rotating wall vessel (RWV) bioreactor. The resulting TEVG demonstrates anisotropic structural and mechanical properties similar to that of native blood vessels.