Hydrostatic Pressure Differentially Regulates Outer and Inner Annulus Fibrosus Cell Matrix Production in 3D Scaffolds

Mechanical stimulation may be used to enhance the development of engineered constructs for the replacement of load bearing tissues, such as the intervertebral disc. This study examined the effects of dynamic hydrostatic pressure (HP) on outer and inner annulus (OA, IA) fibrosus cells seeded on fibrous poly(glycolic acid)-poly(L-lactic acid) scaffolds. Constructs were pressurized (5 MPa, 0.5 Hz) for four hours/day from day 3 to day 14 of culture and analyzed using ELISAs and immunohistochemistry (IHC) to assess extracellular matrix (ECM) production. Both cell types were viable, with OA cells exhibiting more infiltration into the scaffold, which was enhanced by HP. ELISA analyses revealed that HP had no effect on type I collagen production while a significant increase in type II collagen (COL II) was measured in pressurized OA constructs compared to day 14 unloaded controls. Both OA and IA dynamically loaded scaffolds exhibited more uniform COL II elaboration as shown by IHC analyses, which was most pronounced in OA-seeded scaffolds. Overall, HP resulted in enhanced ECM elaboration and organization by OA-seeded constructs, while IA-seeded scaffolds were less responsive. As such, hydrostatic pressurization may be beneficial in annulus fibrosus tissue engineering when applied in concert with an appropriate cell source and scaffold material

Induction of osteoblast differentiation markers in human dermal fibroblasts: potential application to bone tissue engineering.

Tissue engineered constructs have the potential to be used as replacements for current bone graft technologies. One component necessary for bone tissue engineering is a readily available, osteogenic cell source. Human dermal fibroblasts may have the potential to differentiate along an osteoblastic lineage, making them a candidate for use in bone tissue engineering applications. The objective of this study was to validate the ability of dermal fibroblasts to express gene and protein markers of osteoblastic differentiation and to explore their potential, in combination with biomaterial scaffolds and signaling factors, for use in bone tissue engineering

Stratigraphy and Conodont Paleontology of the Salamonie Dolomite and Lee Creek Member of the Brassfield Limestone (Silurian) In Southeastern Indiana and Adjacent Kentucky

Indiana Geological Survey Bulletin 40Zonation established by study of the conodont faunas of the Lee Creek Member (new member) of the Brassfield Limestone and of the Salamonie Dolomite, both of Silurian age, from 42 sections in southeastern Indiana and north-central Kentucky differs from the conodont zonation established by O. H. Walliser in 1964 for the lower Silurian and lower part of the middle Silurian rocks of the Carnic Alps of Europe. Three conodont assemblage zones are named. In ascending order these are the Icriodina irregularis Assemblage Zone, the Neospathognathodus celloni Assemblage Zone, and the Pterospathodus amorphognathoides-Spathognathodus ranuliformis Assemblage Zone. These zones correspond in general with the upper part of Walliser’s Bereich I and with his celloni-and amorphognathoides-Zones. The new name Lee Creek Member is applied to a thin dolomite unit at the top of the Brassfield Limestone. Fifty-nine named species, 16 of them new, belonging to 22 genera, two of them new, were identified from about 8,900 specimens obtained in this study. The new taxa include the genera Diadelognathus and Neospathognathodus and the species Diadelognathus compressus, D. excertus, D. primus, Drepanodus aduncus, Ligonodina petila, Neospathognathodus bullatus, N. ceratoides, N. latus, Ozarkodina hanoverensis, 0. neogaertneri, Spathognathodus hadros, S. polinclinatus, Synprioniodina? variabilis, Trichonodella asymmetrica, T.? expansa, and T. papilio. Two species each of Diadelognathus and of Paltodus, and one each of Carniodus, Distacodus?, and Trichonodella are described but not named.Indiana Department of Natural Resource

Photo-Crosslinked Alginate Hydrogels Support Enhanced Matrix Accumulation by Nucleus Pulposus Cells in Vivo

Objective Intervertebral disc (IVD) degeneration is a major health concern in the United States. Replacement of the nucleus pulposus (NP) with injectable biomaterials represents a potential treatment strategy for IVD degeneration. The objective of this study was to characterize the extracellular matrix (ECM) assembly and functional properties of NP cell-encapsulated, photo-crosslinked alginate hydrogels in comparison to ionically crosslinked alginate constructs. Methods Methacrylated alginate was synthesized by esterification of hydroxyl groups with methacrylic anhydride. Bovine NP cells were encapsulated in alginate hydrogels by ionic crosslinking using CaCl2 or through photo-crosslinking upon exposure to long-wave UV light in the presence of a photoinitiator. The hydrogels were evaluated in vitro by gross and histological analysis and in vivo using a murine subcutaneous pouch model. In vivo samples were analyzed for gene expression, ECM localization and accumulation, and equilibrium mechanical properties. Results Ionically crosslinked hydrogels exhibited inferior proteoglycan accumulation in vitro and were unable to maintain structural integrity in vivo. In further studies, photo-crosslinked alginate hydrogels were implanted for up to 8 weeks to examine NP tissue formation. Photo-crosslinked hydrogels displayed temporal increases in gene expression and assembly of type II collagen and proteoglycans. Additionally, hydrogels remained intact over the duration of the study and the equilibrium Young\u27s modulus increased from 1.24 ± 0.09 kPa to 4.31 ± 1.39 kPa, indicating the formation of functional matrix with properties comparable to those of the native NP. Conclusions These findings support the use of photo-crosslinked alginate hydrogels as biomaterial scaffolds for NP replacement

Giant Stark effect in the emission of single semiconductor quantum dots

We study the quantum-confined Stark effect in single InAs/GaAs quantum dots embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing the barrier height we can observe emission from a dot at electric fields of -500 kV/cm, leading to Stark shifts of up to 25 meV. Our results suggest this technique may enable future applications that require self-assembled dots with transitions at the same energy

Effective average action in statistical physics and quantum field theory

An exact renormalization group equation describes the dependence of the free energy on an infrared cutoff for the quantum or thermal fluctuations. It interpolates between the microphysical laws and the complex macroscopic phenomena. We present a simple unified description of critical phenomena for O(N)-symmetric scalar models in two, three or four dimensions, including essential scaling for the Kosterlitz-Thouless transition.Comment: 34 pages,5 figures,LaTe

Effect of root spacing on interpretation of blade penetration tests-full-scale physical modelling

The spatial distribution of plant roots is an important parameter when the stability of vegetated slopes is to be assessed. Previous studies in both laboratory and field conditions have shown that a penetrometer adapted with a blade-shaped tip can be used to detect roots from sudden drops in penetrometer resistance. Such drops can be related to root properties including diameter, stiffness and strength using simpleWinkler foundation models, thereby providing a field instrument for rapid quantification of root properties and distribution. While this approach has proved useful for measuring single widely-spaced roots, it has not previously been determined how the penetrometer response changes as a result of roots being in close proximity. Therefore in this study 1-g physical modelling (at 1:1 scale) was conducted to study the effect of vertical root spacing using horizontal, straight 3D-printed root analogues. Results showthatwhen roots are closely spaced, there is significant interaction between them, resulting in higher apparent root displacements to failure and an increased amount of energy being dissipated. This preliminary work shows that the interpretive models used to analyse the penetrometer trace require further development to account for root-soil-root interactions in densely rooted soil.</p

Concepciones alternativas de los estudiantes de la Escuela Normal Superior Distrital María Montessori del grado 902 en torno al concepto de ecosistema

Alternative concepts are important for the teaching-learning process since they should be taken as a basis for the construction of knowledge in the classroom. The present study was developed with the objective of identifying and categorizing the alternative conceptions of 30 students of grade 902 of the Escuela Normal Superior Distrital María Montessori de Bogotá around the concept of ecosystem from the application of a diagnostic instrument; the alternative conceptions of the students were classified in levels 0, 1, 2 and 3 of complexity. Fifty percent of the definitions were located in level 1 of complexity (additive level) and only 10% of the definitions were identified in level 3 of complexity (complex organizational level). The usefulness of images for the detection of alternative conceptions is also identified.Las concepciones alternativas son importantes para el proceso de enseñanza-aprendizaje ya que deben tomarse como base para la construcción de conocimientos en el aula. El presente estudio se desarrolló con el objetivo de identificar y categorizar las concepciones alternativas de 30 estudiantes del grado 902 de la Escuela Normal Superior Distrital María Montessori de Bogotá alrededor del concepto de ecosistema a partir de la aplicación de un instrumento diagnóstico; las concepciones alternativas de los estudiantes fueron clasificadas en los niveles 0, 1, 2 y 3 de complejidad. El 50% de las definiciones se ubicaron en el nivel 1 de complejidad (nivel aditivo) y sólo el 10% de las definiciones se identificaron en el nivel 3 de complejidad (nivel de organización compleja). Se evidencia la utilidad del uso de imágenes para la detección de concepciones alternativas

Comparison of new <i>in situ </i>root-reinforcement measuring devices to existing techniques

Mechanical root-reinforcement is difficult to quantify. Existing in-situ methods are cumbersome, while modelling requires parameters which are difficult to acquire. In this paper, two new in-situ measurement devices are introduced ('cork screw' and 'pin vane') and their performance is compared to field vane and laboratory direct shear strength measurements in fallow and rooted soil. Both new methods show a close correlation with field vane readings in fallow soil. Tests in reinforced soil show that both new methods can be installed without significant root disturbance. The simplicity of both new methods allows for practical in-situ use and both can be used to study soil stress-strain behaviour, thus addressing some major limitations in existing methodologies for characterising rooted soil.</p