Synthesis and Characterization of 2-Decenoic Acid Modified Chitosan for Infection Prevention and Tissue Engineering

Chitosan nanofiber membranes are recognized as functional antimicrobial materials, as they can effectively provide a barrier that guides tissue growth and supports healing. Methods to stabilize nanofibers in aqueous solutions include acylation with fatty acids. Modification with fatty acids that also have antimicrobial and biofilm-resistant properties may be particularly beneficial in tissue regeneration applications. This study investigated the ability to customize the fatty acid attachment by acyl chlorides to include antimicrobial 2-decenoic acid. Synthesis of 2-decenoyl chloride was followed by acylation of electrospun chitosan membranes in pyridine. Physicochemical properties were characterized through scanning electron microscopy, FTIR, contact angle, and thermogravimetric analysis. The ability of membranes to resist biofilm formation by S. aureus and P. aeruginosa was evaluated by direct inoculation. Cytocompatibility was evaluated by adding membranes to cultures of NIH3T3 fibroblast cells. Acylation with chlorides stabilized nanofibers in aqueous media without significant swelling of fibers and increased hydrophobicity of the membranes. Acyl-modified membranes reduced both S. aureus and P. aeruginosa bacterial biofilm formation on membrane while also supporting fibroblast growth. Acylated chitosan membranes may be useful as wound dressings, guided regeneration scaffolds, local drug delivery, or filtration.     

Changes in anthropogenic impervious surfaces,precipitation and daily streamflow discharge: a historical perspective in a mid-atlantic subwatershed

Aerial photography provides a historical vehicle for determining long-term urban landscape change and, with concurrent daily streamflow and precipitation records, allows the historical relationship of anthropogenic impervious surfaces and streamflow to be explored. Anthropogenic impervious surface area in the upper Accotink Creek subwatershed (near Annandala, Virginia, USA) was mapped from six dates of rectified historical aerial photography ranging from 1949 to 1994. Results show that anthropogenic impervious surface area has grown from approximately 3% in 1949 to 33% in 1994. Coincident to this period, analysis of historical mean daily streamflow shows a statistically significant increase in the streamflow discharge response (per meter of precipitation) associated with normal and extreme daily precipitation levels. Significant changes were also observed in the frequency of daily streamflow discharge at given volumes above and below the historical daily mean. Simultaneously, the historical magnitude, frequency and pattern of precipitation values 0 mm, 6.0 mm and 35.0 mm show either no statistically significant change or influence on streamflow. Historical changes in streamflow in this basin appear to be related to increases in anthropogenic impervious surface cover. Historical aerial photography is a viable tool for revealing long-term landscape and ecosystem relationships, and allows landscape investigations to extend beyond the temporal and spatial constraints of historical satellite remote sensing data.This revised version was published online in May 2005 with corrections to the Cover Date.     

Biomass management targets and the conservation and economic benefits of marine reserves

The establishment of no‐take marine reserves has been increasingly promoted as a key measure to achieve conservation and sustainability goals in fisheries. Regardless of the wide range of benefits cited, the effectiveness of reserve establishment depends critically on fisheries management outside the reserves. We construct a bioeconomic model of a fishery that allows for the establishment of a no‐take marine reserve and evaluate how the choice of the off‐reserve management target influences the effectiveness of reserve establishment. We evaluate two biomass targets: (i) B_MSY or the biomass that produces the maximum sustainable yield (MSY) and (ii) B_MEY or the biomass that maximizes the net present value of the returns to fishing. The parameterized model shows that, for a wide range of scenarios, the fishery will be better off in terms of both conservation and economic objectives when the no‐take reserve is established in conjunction with the B_MEY target rather than with the B_MSY target. Model results further show that the opportunity cost of securing additional fish biomass, in both deterministic and stochastic environments, is lower when the reserve size is increased under the B_MEY target. This finding is important because marine reserves have been established as a key measure to restore depleted fish stocks, and the results suggest that this objective can be achieved with lower economic costs in a B_MEY managed fishery.     

A leaf-blotch disorder of tayberry associated with the leaf and bud mite (Phyllocoptes gracilis) and some effects of three aphid-borne viruses

Tayberry plants showing conspicuous chlorotic blotches, ringspots, leaf distortion and lacking vigour were found at two sites in Scotland. The severity of the symptoms and the number of plants affected increased annually and reached 100% incidence at one site. No mechanically transmissible virus was detected in affected plants, but many such plants and some symptomless ones contained viruses indistinguishable in Rubus indicator plants from black raspberry necrosis, raspberry leaf mottle and raspberry leaf spot viruses. Propagants from healthy tayberry plants graft-inoculated either with these three viruses, singly and in combinations, or with scions from symptom-bearing tayberry, showed a faint chlorotic mottle when grown outdoors or in an unheated glasshouse but none developed the severe symptoms observed in the field. Leaves and buds of field-affected plants were found to be infested with large numbers of eriophyid mites at both sites. A single application of vamidothion to affected plants at one site resulted in significantly fewer mites and less severe symptoms on fruiting canes and primocanes than on unsprayed plants in the year of spraying and a further decrease in symptoms in the following year. The symptomatology, occurrence in Scotland and the decrease in symptoms following the application of vamidothion indicate that the disorder is caused by infestations by the leaf and bud mite (Phyllocoptes gracilis).     

An alternative pathway electrosurgical unit injury in a dog

Objective: To report esophageal perforation, caused by alternative current pathway from the use of a monopolar electrosurgery unit (ESU), during routine orthopedic surgery in a dog. Study Design: Clinical report. Animals: Two‐year‐old male Labrador retriever. Methods: Medial meniscectomy and lateral suture stabilization were performed on a healthy Labrador retriever with a ruptured cranial cruciate ligament. Monopolar electrosurgery was used during the procedure for hemostasis and tissue dissection. Anesthetic monitoring was augmented with an esophageal electrocardiogram (ECG) probe. The day after surgery, the dog appeared dehydrated. After intravenous fluid therapy, respiratory distress was noted and thoracic radiography and contrast fluoroscopy revealed an esophageal perforation. Results: Exploratory surgery was planned to repair the defect. Cardiac arrest occurred after induction. Gross necropsy findings and histopathologic examination revealed lesions consistent with thermal necrosis of the esophagus and myocardial degeneration. An internal investigation of this medical device accident revealed that multiple factors may have contributed to the injury. Conclusions: An alternative current pathway from the monopolar ESU to the esophageal ECG probe resulted in a full‐thickness esophageal thermal injury and cardiac failure.     

Characterization and origin of infection of Rhizoctonia solani associated with Brassica oleracea crops in the UK

An extensive study was conducted to determine where in the production chain Rhizoctonia solani became associated with UK module-raised Brassica oleracea plants. In total, 2600 plants from 52 crops were sampled directly from propagators and repeat sampled from the field. Additional soil, compost and water samples were collected from propagation nurseries and screened using conventional agar isolation methods. No isolates of R. solani were recovered from any samples collected from propagation nurseries. Furthermore, nucleic acid preparations from samples of soil and compost from propagation nurseries gave negative results when tested for R. solani using real-time PCR. Conversely, R. solani was recovered from 116 of 1300 stem bases collected from field crops. All the data collected suggested R. solani became associated with B. oleracea in the field rather than during propagation. Parsimony and Bayesian phylogenetic studies of ribosomal DNA suggested the majority of further classified isolates belonged to anastomosis groups 2-1 (48/57) and AG-4HGII (8/57), groups known to be pathogenic on Brassica spp. in other countries. Many R. solani isolates were recovered from symptomless plant material and the possibilities for such an association are discussed.     

Further evidence on the effects of gene H,which confers cane hairyness,on resistance to raspberry diseases

Summary Gene H determines cane hairyness in raspberries and was reported to facilitate escape from infection by Botrytis cinerea and Didymella applanata. However, experiments with mycelial inoculations of wounded canes showed that it conferred a form of resistance which was evident for a long period after the establishment of infections by these pathogens. The gene also contributed to the resistance of fruit to B. cinerea and of canes to Leptosphaeria coniothyrium. Alternative hypotheses to explain these observations are discussed: two based upon its possible genetic linkage with a gene or genes for resistance and one based upon its possible pleiotropic effects.     

Dendryphion penicillatum and Pleospora papaveracea, Destructive Seedborne Pathogens and Potential Mycoherbicides for Papaver somniferum

ABSTRACT Dendryphion penicillatum and Pleospora papaveracea were isolated from blighted Papaver somniferum and Papaver bracteatum plants grown in growth chambers and the field in Beltsville, MD. The etiology of the diseases was determined, and the fungi are being investigated as potential mycoherbicides to control the narcotic opium poppy plant. P. papaveracea is known to be a highly destructive seedborne pathogen of Papaver somniferum, causing seedling blight, leaf blight, crown rot, and capsule rot. Single conidia and ascospores were isolated and cultures established from naturally infested seed and diseased foliage and pods of opium poppy from Iran, Colombia, Venezuela, Sweden, India, and the United States (Maryland and Washington). Mycelia and conidia of P. papaveracea and D. penicillatum produced on necrotic leaf tissues appear morphologically similar, and the fungi were previously considered to be anamorph and teleomorph. However, no anamorph/teleomorph connection could be established, and the fungi appear to be distinct taxa. P. papaveracea produced conidia, mature pseudothecia, and chlamydospores in vitro and on infected stems. D. penicillatum produced conidia, microsclerotia, and macronematous conidiophores. Although both fungi were pathogenic to three poppy cultivars, conidial inoculum from P. papaveracea cultures was more virulent than conidial inoculum from D. penicillatum. Eight-week-old plants became necrotic and died 8 days after inoculation with a conidial suspension of P. papaveracea at 2 x 10(5) spores per ml. Disease severity was significantly enhanced by inoculum formulations that contained corn oil, by higher conidial inoculum concentrations, and by increased wetness periods. Symptoms on plants inoculated with either pathogen included leaf and stem necrosis, stem girdling, stunting, necrotic leaf spots, and foliar and pod blight. Inoculated seedlings exhibited wire stem, damping-off, and root rot. Conidia, and less frequently pseudothecia, of P. papaveracea and conidia of D. penicillatum were produced abundantly on inoculated, necrotic foliage, pods, and seedlings. Cultures from conidia or ascospores reisolated from these tissues consistently produced fungi whose morphologies were typical of the fungus from which the inoculum was derived.