Studies of farming symbols in modern agriculture indicate that soils and agricultural land are important factors when it comes to the construction of farmers' identities. This article uses Bourdieu's ...framework of habitus along with his theory of capital to discuss the importance of soils in this construction process of farmers' identities. A range of methods was used in this study involving qualitative and quantitative interviews with 124 farmers in the Austrian province of Burgenland. In the Burgenland, soil and landscapes are loaded with meaning and therefore never neutral: always implying a wide range of moral concepts of what is “good” or “bad” in the context of soil and land. Farmers “read” soils and related management practices as indication of farming skills and the farmers' interpretation always depends on farmers' aesthetic perception of the world and thus on the farmers' habitus and cultural capital. Farmers distinguish themselves from other farmers, groups or areas of work relating to soil quality aspects or soil management strategies of others. This reciprocal construction of boundaries locates the standing of individual farmers within a community. The importance of the relation between farmers and their soils for the construction of farming identity is especially important for organic farmers.
•Soil quality aspects are important factors for constructing farmers' identities.•The perception of soils among farmers always implies a whole range of moral values.•Farmers define themselves against other farmers or groups in relation to soil quality aspects.•Soils say something about farming skills to anyone who is able to decode farming symbols.•Soil quality aspects locate the social standing of farmers within the farming community.
A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. Metallic coronary stents were first introduced to ...prevent arterial dissections and to eliminate vessel recoil and intimal hyperplasia associated with percutaneous transluminal coronary angioplasty. The stent application range has expanded as more experience was gained, and encouraging results have been obtained in the treatment of vascular diseases. Stents are currently used for support of additional body conduits, including the urethra, trachea, and esophagus. The rationale for bioresorbable stents is the support of a body conduit only during its healing process. The stent mass and strength decrease with time, and the mechanical load is gradually transferred to the surrounding tissue. Bioresorbable stents also enable longer term delivery of drugs to the conduit wall from an internal reservoir and abolish the need for a second surgery to remove the device. The present review describes recent advances in bioresorbable stents, focusing on drug-eluting bioresorbable stents for various applications. Controlled release of an active agent from a stent can be used to enhance healing of the surrounding tissues, to increase the implant's biocompatibility, as well as to help cure certain diseases. Because a lot of research in this field has been done by us, examples for these functions are described based mainly on developments in our laboratories.
The utility of employing a variable duty cycle pulsed plasma polymerization technique to control film chemistry during plasma depositions is examined using allyl alcohol as monomer gas. Large scale ...progressive variations in film composition are observed with sequential changes in the plasma duty cycles employed, all other plasma variables being held constant. In particular, the −OH functionality of the monomer is increasingly retained in the plasma generated thin films as the radio frequency duty cycle is lowered. Fourier transform infrared and X-ray photoelectron spectroscopic analyses of the films obtained reveal that excellent film chemistry control is achieved during plasma polymerization of this monomer. The surface density controllability of functional groups, coupled with a gradient layering technique described herein to improve film adhesion to substrate surfaces, provides ideal opportunities for molecular tailoring of surfaces via subsequent derivatization reactions.
Our objective was to evaluate the hemocompatibility of biodegradable stent fibers, employing a closed-loop circulation system filled with human blood. We also investigated the effects of the ...anti-inflammatory and anti-proliferative drugs curcumin and paclitaxel, incorporated into stent fibers. Fresh whole blood was circulated in four parallel closed-loop systems: the empty tube circuit (control) and tubes containing either a PLLA fiber coil (PLLA), a curcumin-loaded PLLA coil (C-PLLA) or a paclitaxel-loaded PLLA coil (P-PLLA). The influence of PLLA fiber, alone or loaded with drug incorporated during melt-extrusion, on leukocyte and platelet adhesion and activation was determined by flow cytometry. The effects of blood flow and fiber properties on cell deposition were assessed by scanning electron microscopy (SEM). The flow cytometry results clearly demonstrated that PLLA triggers blood cell activation at the site of deployment, as shown by increases in CD11b, CD62P and leukocyte–platelet aggregates, compared to controls. Curcumin and paclitaxel treatments both significantly reduced leukocyte and platelet activation and adhesion to PLLA fibers, as shown by flow cytometry and SEM. Activated leukocytes and platelets revealed significantly lower CD11b and CD62P receptor binding for C-PLLA compared with PLLA alone, and slightly lower for P-PLLA. Reductions in platelet–leukocyte aggregates were observed as well. In addition, there was less leukocyte and platelet adhesion to C-PLLA, compared with PLLA fiber controls, as shown by SEM. A continuous linear thrombus, composed of platelets, leukocytes, red blood cells and fibrin was occasionally detected along the line of tangency between the coil and the tube wall. Flow separation and eddying, proximal and distal to the line of tangency of coil and tube, is thought to contribute to this deposit. Curcumin was more effective than paclitaxel in reducing leukocyte and platelet activation and adhesion to PLLA stent fibers in this setting. However there was evidence of paclitaxel degeneration during melt extrusion that may have inhibited its effectiveness. Incorporation of the anti-inflammatory and anti-proliferative drug curcumin into bioresorbable stent fibers is proposed to prevent thrombosis and in-stent restenosis.
Metal stents and, more recently, polymer-coated metal stents are used to stabilize dissections, eliminate vessel recoil, and guide remodeling after balloon angioplasty and other treatments for ...arterial disease. Bioresorbable polymeric stents are being developed to improve the biocompatibility and the drug reservoir capacity of metal stents, and to offer a transient alternative to the permanent metallic stent implant. Following a brief review of metal stent technology, the emerging class of expandable, bioresorbable polymeric stents is described, with emphasis on developments in the authors' laboratory.
A bioresorbable, expandable poly(L-lactic acid) stent has been designed, based on a linear, continuous coil array principle, by which multiple furled lobes convert to a single lobe upon balloon ...expansion, without heating. Stent strength and compliance are sufficient to permit deployment by a conventional balloon angioplasty catheter. Several multiple lobe configurations were investigated, with expansion ratios ranging from 1.4 to 1.9 and expanded diameters ranging from 2.3 to 4.7 mm. Compression resistance of the expanded stent is dependent on fiber coil density and fiber ply. A range sufficient for endovascular service was obtained, with less than 4% elastic recoil in six day saline incubation studies. Surface plasma treatment with di(ethylene glycol) vinyl ether significantly reduced platelet adhesion in a 1 h porcine arteriovenous shunt model. Patency was maintained in one week implant studies in the porcine common femoral artery. However, a strong inflammatory response, and significant reduction of the vascular lumen were observed following two weeks implantation. The design principles and fabrication techniques for this bioresorbable stent are sufficiently versatile that a broad range of applications can be addressed. Much work remains to be done, including long-term evaluation of the inflammatory response, and of polymer degradation. The results of this study demonstrate the feasibility of expandable biodegradable stent design and deployment by conventional means.
We investigated poly(L-lactic acid) (PLLA) fibers and coils, simulating stents and the influence of impregnation with curcumin, a non-steroidal anti-inflammatory drug, intended to reduce the ...pro-inflammatory property of these implants. Fibers obtained by melt extrusion of 137 kDa PLLA
resin containing 10% curcumin (C-PLLA) exhibited a stable curcumin release rate for periods up to 36 days. Curcumin increased the fiber tensile strength at break and decreased embrittlement vs . controls in 36 day 37°C saline incubation. A mouse peritoneal phagocyte model was employed
to test the anti-inflammatory properties of C-PLLA fibers in vitro. Myeloperoxidase and non-specific esterase activity assays were performed for adherent cells (polymorphonuclear leukocytes (PMN) and macrophages (MΦ), respectively). PMN and MΦ adhesion to C-PLLA
fibers were significantly reduced compared to control PLLA fibers (2.6 ± 0.91) × 10
5
vs. (5.6 ± 0.67) × 10
5
PMN/cm
2
and (3.9 ± 0.23) × 10
3
vs. (9.1 ± 0.7) × 10
3
MΦ/cm
2
(P < 0.05), respectively. In addition, superoxide release in the phagocyte pool contacting C-PLLA fibers was 97% less than that for PLLA controls. A fresh human whole blood recirculation system was employed to analyze cell adhesion under flow conditions, employing scanning electron
microscopy (SEM). Reduced adhesion of cells on C-PLLA fiber coils vs. controls was observed. These in vitro studies demonstrate that bulk curcumin impregnation can reduce the inflammatory response to bioresorbable PLLA fibers, whilst improving mechanical properties, thereby suggesting
curcumin loading may benefit PLLA-based implants.
The amnesic shellfish poison domoic acid is produced by marine algae of the genus
Pseudo-nitzschia. We have developed a portable surface plasmon resonance (SPR) biosensor system for the detection of ...domoic acid. Because of concerns with domoic acid contamination of shellfish, there is a need for rapid field quantification of toxin levels in both shellfish and seawater. Antibodies were raised against domoic acid and affinity purified. These antibodies were used to develop competition- and displacement-based assays using a portable six-channel SPR system developed in our laboratories. Standard curves for detection of domoic acid in phosphate buffered saline and in diluted clam extracts analyzed by the competition-based SPR assay demonstrated a limit of detection of 3
ppb (10
nM) and a quantifiable range from 4 to 60
ppb (13–200
nM). Comparison of analyses for domoic acid levels in Pacific razor clams,
Siliqua patula, containing moderate to high levels of domoic acid by the standard HPLC analysis protocol and the SPR-based assay gave an excellent correlation. This same technology should also function for detection of domoic acid in concentrated algal extracts or high dissolved levels in seawater.
