Imaging of Tyramine-Substituted Hydrogels for Tissue Replacement

Novel tyramine-based hyaluronan (HA) and collagen hydrogels have been developed in which cross-linking is accomplished via peroxidase-mediated dityramine linkages allowing direct cross-linking in vivo. These TB hydrogels possess advantageous physical properties, which include excellent biocompatibility and the ability to mimic the biological, structural and mechanical properties of normal, healthy tissues, including cartilage, and thus provide for synthetic, implantable biomaterials suitable for a wide range of tissue types. The efficacy of these TB-hydrogels has been previously tested in a number of clinically relevant animal models, which have evaluated their applicability for the repair/replacement of various tissues, including cartilage. Nevertheless, there exists a fundamental need for non-destructive methods to identify, distinguish, quantify and trace these biomaterials in vivo. Magnetic Resonance Imaging (MRI) is a broadly used non-invasive clinical imaging methodology that allows direct visualization of soft tissues. Our results indicated that T1 and T2 mapping can differentiate and measure changes in HA and collagen concentration both alone and in combination with composite materials, composed of HA and collagen at the concentrations found in cartilage resulting in T1 values representative of cartilage. Furthermore, the dGEMRIC technique was able to quantify the HA concentration in phantoms of known HA concentration. These MRI techniques could detect and differentiate the tyramine-based hydrogels in implanted joints, and accurately quantify their volume

Imaging of Tyramine-Substituted Hydrogels for Tissue Replacement

Novel tyramine-based hyaluronan (HA) and collagen hydrogels have been developed in which cross-linking is accomplished via peroxidase-mediated dityramine linkages allowing direct cross-linking in vivo. These TB hydrogels possess advantageous physical properties, which include excellent biocompatibility and the ability to mimic the biological, structural and mechanical properties of normal, healthy tissues, including cartilage, and thus provide for synthetic, implantable biomaterials suitable for a wide range of tissue types. The efficacy of these TB-hydrogels has been previously tested in a number of clinically relevant animal models, which have evaluated their applicability for the repair/replacement of various tissues, including cartilage. Nevertheless, there exists a fundamental need for non-destructive methods to identify, distinguish, quantify and trace these biomaterials in vivo. Magnetic Resonance Imaging (MRI) is a broadly used non-invasive clinical imaging methodology that allows direct visualization of soft tissues. Our results indicated that T1 and T2 mapping can differentiate and measure changes in HA and collagen concentration both alone and in combination with composite materials, composed of HA and collagen at the concentrations found in cartilage resulting in T1 values representative of cartilage. Furthermore, the dGEMRIC technique was able to quantify the HA concentration in phantoms of known HA concentration. These MRI techniques could detect and differentiate the tyramine-based hydrogels in implanted joints, and accurately quantify their volume

Imaging of Tyramine-Substituted Hydrogels for Tissue Replacement

Novel tyramine-based hyaluronan (HA) and collagen hydrogels have been developed in which cross-linking is accomplished via peroxidase-mediated dityramine linkages allowing direct cross-linking in vivo. These TB hydrogels possess advantageous physical properties, which include excellent biocompatibility and the ability to mimic the biological, structural and mechanical properties of normal, healthy tissues, including cartilage, and thus provide for synthetic, implantable biomaterials suitable for a wide range of tissue types. The efficacy of these TB-hydrogels has been previously tested in a number of clinically relevant animal models, which have evaluated their applicability for the repair/replacement of various tissues, including cartilage. Nevertheless, there exists a fundamental need for non-destructive methods to identify, distinguish, quantify and trace these biomaterials in vivo. Magnetic Resonance Imaging (MRI) is a broadly used non-invasive clinical imaging methodology that allows direct visualization of soft tissues. Our results indicated that T1 and T2 mapping can differentiate and measure changes in HA and collagen concentration both alone and in combination with composite materials, composed of HA and collagen at the concentrations found in cartilage resulting in T1 values representative of cartilage. Furthermore, the dGEMRIC technique was able to quantify the HA concentration in phantoms of known HA concentration. These MRI techniques could detect and differentiate the tyramine-based hydrogels in implanted joints, and accurately quantify their volume

Vacua and correlators in hyperbolic de Sitter space

We study the power - and bi -spectrum of vacuum fluctuations in a hyperbolic section of de Sitter space, comparing two states of physical interest: the Bunch-Davies and hyperbolic vacuum. We introduce a one -parameter family of de Sitter hyperbolic sections and their natural vacua, and identify a limit in which it reduces to the planar section and the corresponding Bunch -Davies vacuum state. Selecting the Bunch -Davies vacuum for a massless scalar field implies a mixed reduced density matrix in a hyperbolic section of de Sitter space. We stress that in the Bunch -Davies state the hyperbolic de Sitter $n$-point correlation functions have to match the planar de Sitter $n$-point correlation functions. The expressions for the planar and hyperbolic Bunch -Davies correlation functions only appear different because of the transformation from planar to hyperbolic coordinates. Initial state induced deviations from the standard inflationary predictions are instead obtained by considering the pure hyperbolic vacuum, as we verify explicitly by computing the power - and bi -spectrum. For the bi -spectrum in the hyperbolic vacuum we find that the corrections as compared to the standard Bunch -Davies result are not enhanced in specific momentum configurations and strongly suppressed for momenta large compared to the hyperbolic curvature scale. We close with some final remarks, in particular regarding the implications of these results for more realistic inflationary bubble scenarios.Comment: Added references, removed typos, added author, extensions in first section and conclusions. 34 pages, 4 figure

Artificial Intelligence and Image Processing

The evolution of artificial intelligence since the 1950s is discussed, especially as it is being applied in radiology to image processing. Developments in artificial intelligence are now being used to provide a new approach to image processing. Initially, the computer dealt with numeric representations using languages such as FORTRAN and BASIC. Now symbolic languages such as LISP and PROLOG have expanded the use of the computer into nonnumeric symbolic reasoning that is just being applied to image understanding. This paper explains the new languages and their application to image understanding

Synthesis method for linkages with conter of mass at invariant link point-Pantograph based mechnisms

This paper deals with the synthesis of the motion of the center of mass (CoM) of linkages as being a stationary or invariant point at one of its links. This is of importance for the design of inherently shaking force balanced mechanisms, static balancing, and other branches of mechanical synthesis. For this purpose Fischer's mechanism is investigated as being a composition of pantographs. It can be shown that linkages that are composed of pantographs and of which all links have an arbitrary CoM can be inherently balanced for which Fischer's method is a useful tool. To calculate the principal dimensions for which linkages have their CoM at an invariant link point, an approach based on linear momentum is proposed. With this approach it is possible to investigate each degree-of-freedom individually. Equivalent Linear Momentum Systems are proposed to facilitate the calculations in order to use different convenient reference frames. The method is applied to planar linkages with revolute joints, however it also applies to linkages with other types of joints. As a practical example a shaking force and shaking moment balanced 2-DoF grasper mechanism is derived. -------------------------------------------------------------------------------

Uso de microarrays para a análise do perfil transcricional em polpa de maçã cv. Gala frente ao armazenamento refrigerado e ao uso do 1-metilciclopropeno.

O presente trabalho utilizou a técnica de microarrays para o estudo da influência do 1-metilciclopropeno (1-MCP) e do AR sobre o perfil transcricional de polpa de maçã 'Gala' armazenada por 60 dias