Adopting stewardship contracting : lessons from four national forests

4 pagesCongress granted broad stewardship contracting authority to the Forest Service and the Bureau of Land Management in the FY 2003 appropriations act to help these agencies accomplish restoration and hazardous fuels reduction and increase community benefit from these activities. During the first several years of the authority, the use of stewardship contracting was uneven, with some national forests making significant use of the authorities while others hardly used stewardship contracting at all. Although the stewardship contracting has become more wide spread in recent years, it is not clear why some national forests were early adopters and others were more hesitant to use the authorities. This study provides insight into the question of why the use of stewardship contracting was initially so variable.This briefing paper was made possible with funding from the USDA Forest Service, National Fire Plan, Ford Foundation, and University of Oregon

The development of a ε-polycaprolactone (PCL) scaffold for CNS repair

Potential treatment strategies for the repair of spinal cord injury (SCI) currently favour a combinatorial approach incorporating several factors, including exogenous cell transplantation and biocompatible scaffolds. The use of scaffolds for bridging the gap at the injury site is very appealing although there has been little investigation into CNS neural cell interaction and survival on such scaffolds before implantation. Previously we demonstrated that aligned micro-grooves 12.5-25 µm wide on ε-polycaprolactone (PCL) promoted aligned neurite orientation and supported myelination. In this study we identify the appropriate substrate and its topographical features required for the design of a 3D scaffold intended for transplantation in SCI. Using an established myelinating culture system of dissociated spinal cord cells, recapitulating many of the features of the intact spinal cord, we demonstrate that astrocytes plated on the topography secrete soluble factors(s) that delay oligodendrocyte differentiation but do not prevent myelination. However, as myelination does occur after a further 10-12 days in culture this does not prevent the use of PCL as a scaffold material as part of a combined strategy for the repair of SCI

A miniaturized bioreactor system for the evaluation of cell interaction with designed substrates in perfusion culture

In tissue engineering, the chemical and topographical cues within three-dimensional (3D) scaffolds are normally tested using static cell cultures but applied directly to tissue cultures in perfusion bioreactors. As human cells are very sensitive to the changes of culture environment, it is essential to evaluate the performance of any chemical, and topographical cues in a perfused environment before they are applied to tissue engineering. Thus the aim of this research was to bridge the gap between static and perfusion cultures by addressing the effect of perfusion on cell cultures within 3D scaffolds. For this we developed a scale down bioreactor system, which allows to evaluate the effectiveness of various chemical and topographical cues incorporated into our previously developed tubular ε-polycaprolactone scaffold under perfused conditions. Investigation of two exemplary cell types (fibroblasts and cortical astrocytes) using the miniaturized bioreactor indicated that: (1) quick and firm cell adhesion in 3D scaffold was critical for cell survival in perfusion culture compared with static culture, thus cell seeding procedures for static cultures might not be applicable. Therefore it was necessary to re-evaluate cell attachment on different surfaces under perfused conditions before a 3D scaffold was applied for tissue cultures, (2) continuous medium perfusion adversely influenced cell spread and survival, which could be balanced by intermittent perfusion, (3) micro-grooves still maintained its influences on cell alignment under perfused conditions, while medium perfusion demonstrated additional influence on fibroblast alignment but not on astrocyte alignment on grooved substrates. This research demonstrated that the mini-bioreactor system is crucial for the development of functional scaffolds with suitable chemical and topographical cues by bridging the gap between static culture and perfusion culture

Phylogenetic Relationships of Torreya (Taxaceae) Inferred from Sequences of Nuclear Ribosomal DNA ITS Region

Torreya, composed of five to seven species, is distributed disjunctly in easten Asia and the eastern and western United States. In this study, interspecific relationships of Torreya were examined on the basis of sequences of the nrDNA ITS region. Torreya taxifolia and T. californica of the New World form a clade, as do the Old World species. This result suggests that the previous division of Torreya into two sections does not reflect phylogenetic relationships and that the diagnostic character for the two sections, namely rumination of albumen, is homoplastic. It is possible that the present distribution of species of Torreya resulted from a single vicariance event separating the Old World and New World. However, the modern species are apparently young in age, and it will be necessary to integrate older fossils to ascertain the deeper biogeographic history of the genus.Organismic and Evolutionary Biolog

Development of a novel 3D culture system for screening features of a complex implantable device for CNS repair

Tubular scaffolds which incorporate a variety of micro- and nanotopographies have a wide application potential in tissue engineering especially for the repair of spinal cord injury (SCI). We aim to produce metabolically active differentiated tissues within such tubes, as it is crucially important to evaluate the biological performance of the three-dimensional (3D) scaffold and optimize the bioprocesses for tissue culture. Because of the complex 3D configuration and the presence of various topographies, it is rarely possible to observe and analyze cells within such scaffolds in situ. Thus, we aim to develop scaled down mini-chambers as simplified in vitro simulation systems, to bridge the gap between two-dimensional (2D) cell cultures on structured substrates and three-dimensional (3D) tissue culture. The mini-chambers were manipulated to systematically simulate and evaluate the influences of gravity, topography, fluid flow, and scaffold dimension on three exemplary cell models that play a role in CNS repair (i.e., cortical astrocytes, fibroblasts, and myelinating cultures) within a tubular scaffold created by rolling up a microstructured membrane. Since we use CNS myelinating cultures, we can confirm that the scaffold does not affect neural cell differentiation. It was found that heterogeneous cell distribution within the tubular constructs was caused by a combination of gravity, fluid flow, topography, and scaffold configuration, while cell survival was influenced by scaffold length, porosity, and thickness. This research demonstrates that the mini-chambers represent a viable, novel, scale down approach for the evaluation of complex 3D scaffolds as well as providing a microbioprocessing strategy for tissue engineering and the potential repair of SCI

Decreased Survival of B Cells of HIV-viremic Patients Mediated by Altered Expression of Receptors of the TNF Superfamily

Human immunodeficiency virus (HIV) infection leads to numerous perturbations of B cells through mechanisms that remain elusive. We performed DNA microarray, phenotypic, and functional analyses in an effort to elucidate mechanisms of B cell perturbation associated with ongoing HIV replication. 42 genes were up-regulated in B cells of HIV-viremic patients when compared with HIV-aviremic and HIV-negative patients, the majority of which were interferon (IFN)-stimulated or associated with terminal differentiation. Flow cytometry confirmed these increases and indicated that CD21low B cells, enhanced in HIV-viremic patients, were largely responsible for the changes. Increased expression of the tumor necrosis factor (TNF) superfamily (TNFSF) receptor CD95 correlated with increased susceptibility to CD95-mediated apoptosis of CD21low B cells, which, in turn, correlated with HIV plasma viremia. Increased expression of BCMA, a weak TNFSF receptor for B lymphocyte stimulator (BLyS), on CD21low B cells was associated with a concomitant reduction in the expression of the more potent BLyS receptor, BAFF-R, that resulted in reduced BLyS binding and BLyS-mediated survival. These findings demonstrate that altered expression of genes associated with IFN stimulation and terminal differentiation in B cells of HIV-viremic patients lead to an increased propensity to cell death, which may have substantial deleterious effects on B cell responsiveness to antigenic stimulation

Burnt and Blossoming: Material Mysticism in Trilogy and Four Quartets

This paper brings two WWII poems into dialogue: H.D.'s Trilogy and Eliot's Four Quartets. Both poems express a creative response to the destruction of war. My reading of Trilogy suggests a material mysticism in which vision and renewal are situated within the natural world, rituals and bodily experience. Bringing this understanding of mysticism to bear on Four Quartets reveals tension between transcendence and materiality. For Eliot, redemption comes through time and location, while for H.D., redemption lies within material particularity. Four Quartets oscillates between an apophatic discourse that seeks to transcend desire and history and an emphasis on material particularities