A Regional Assessment of Salt Marsh Restoration and Monitoring in the Gulf of Maine

We compiled salt marsh monitoring datasets from 36 complete or imminent restoration projects in the Gulf of Maine to assess regional monitoring and restoration practices. Data were organized by functional indicators and restoration project types (culvert replacement, excavation works, or ditch plugging) then pooled to generate mean values for indicators before restoration, after restoration, and at reference sites. Monitoring data were checked against the regional standards of a voluntary protocol for the Gulf of Maine. Data inventories showed that vegetation and salinity indicators were most frequently collected (89 and 78% of sites, respectively), whereas nekton, bird, and hydrologic measures were collected at only about half of the sites. Reference conditions were monitored at 72% of sites. Indicators were analyzed to see if project sites were degraded relative to reference areas and to detect ecological responses to restoration activities. Results showed that compared to reference areas, prerestoration sites had smaller tidal ranges, reduced salinity levels, greater cover of brackish plants species, and lower cover of halophyte plants. Following restoration, physical factors rebounded rapidly with increased flood and salinity levels after about one year, especially for culvert projects. Biological responses were less definitive and occurred over longer time frames. Plant communities trended toward recovered halophytes and reduced brackish species at 3+ years following restoration. Nekton and avian indicators were indistinguishable among reference, impacted, and restored areas. The protocol was successful in demonstrating restoration response for the region, but results were limited by regional inconsistencies in field practices and relatively few multiyear datasets. To improve future assessment capabilities, we encourage greater adherence to the standard protocol throughout the Gulf of Maine salt marsh restoration community.     

Interferon-inducible CXC chemokines directly contribute to host defense against inhalational anthrax in a murine model of infection

Chemokines have been found to exert direct, defensin-like antimicrobial activity in vitro, suggesting that, in addition to orchestrating cellular accumulation and activation, chemokines may contribute directly to the innate host response against infection. No observations have been made, however, demonstrating direct chemokine-mediated promotion of host defense in vivo. Here, we show that the murine interferon-inducible CXC chemokines CXCL9, CXCL10, and CXCL11 each exert direct antimicrobial effects in vitro against Bacillus anthracis Sterne strain spores and bacilli including disruptions in spore germination and marked reductions in spore and bacilli viability as assessed using CFU determination and a fluorometric assay of metabolic activity. Similar chemokine-mediated antimicrobial activity was also observed against fully virulent Ames strain spores and encapsulated bacilli. Moreover, antibody-mediated neutralization of these CXC chemokines in vivo was found to significantly increase host susceptibility to pulmonary B. anthracis infection in a murine model of inhalational anthrax with disease progression characterized by systemic bacterial dissemination, toxemia, and host death. Neutralization of the shared chemokine receptor CXCR3, responsible for mediating cellular recruitment in response to CXCL9, CXCL10, and CXCL11, was not found to increase host susceptibility to inhalational anthrax. Taken together, our data demonstrate a novel, receptor-independent antimicrobial role for the interferon-inducible CXC chemokines in pulmonary innate immunity in vivo. These data also support an immunomodulatory approach for effectively treating and/or preventing pulmonary B. anthracis infection, as well as infections caused by pathogenic and potentially, multi-drug resistant bacteria including other spore-forming organisms.     

The influence of fibrous elastomer structure and porosity on matrix organization

Fibrous scaffolds are finding wide use in the field of tissue engineering, as they can be designed to mimic many native tissue properties and structures (e.g., cardiac tissue, meniscus). The influence of fiber alignment and scaffold architecture on cellular interactions and matrix organization was the focus of this study. Three scaffolds were fabricated from the photocrosslinkable elastomer poly(glycerol sebacate) (PGS), with changes in fiber alignment (non-aligned (NA) versus aligned (AL)) and the introduction of a PEO sacrificial polymer population to the AL scaffold (composite (CO)). PEO removal led to an increase in scaffold porosity and maintenance of scaffold anisotropy, as evident through visualization, mechanical testing, and mass loss studies. Hydrated scaffolds possessed moduli that ranged between ～3-240 kPa, failing within the range of properties (<300 kPa) appropriate for soft tissue engineering. CO scaffolds were completely degraded as early as 16 days, whereas NA and AL scaffolds had ～90% mass loss after 21 days when monitored in vitro. Neonatal cardiomyocytes, used as a representative cell type, that were seeded onto the scaffolds maintained their viability and aligned along the surface of the AL and CO fibers. When implanted subcutaneously in rats, a model that is commonly used to investigate in vivo tissue responses to biomaterials, CO scaffolds were completely integrated at 2 weeks, whereas ～13% and ～16% of the NA and AL scaffolds, respectively remained acellular. However, all scaffolds were completely populated with cells at 4 weeks post-implantation. Polarized light microscopy was used to evaluate the collagen elaboration and orientation within the scaffold. An increase in the amount of collagen was observed for CO scaffolds and enhanced alignment of the nascent collagen was observed for AL and CO scaffolds compared to NA scaffolds. Thus, these results indicate that the scaffold architecture and porosity are important considerations in controlling tissue formation.     

In vivo glycosylation of mucin tandem repeats.

The biochemical and biophysical properties of mucins are largely determined by extensive O-glycosylation of serine- and threonine-rich tandem repeat (TR) domains. In a number of human diseases aberrant O-glycosylation is associated with variations in the properties of the cell surface-associated and secreted mucins. To evaluate in vivo the O-glycosylation of mucin TR domains, we generated recombinant chimeric mucins with TR sequences from MUC2, MUC4, MUC5AC, or MUC5B, which were substituted for the native TRs of epitope-tagged MUC1 protein (MUC1F). These hybrid mucins were extensively O-glycosylated and showed the expected association with the cell surface and release into culture media. The presence of different TR domains within the chimeric mucins appears to have limited influence on their posttranslational processing. Alterations in glycosylation were detailed by fast atom bombardment mass spectrometry and reactivity with antibodies against particular blood-group and tumor-associated carbohydrate antigens. Future applications of these chimeras will include investigations of mucin posttranslational modification in the context of disease.     

Modeling Habitat Change in Salt Marshes After Tidal Restoration

Salt marshes continue to degrade in the United States due to indirect human impacts arising from tidal restrictions. Roads or berms with inadequate provision for tidal flow hinder ecosystem functions and interfere with self‐maintenance of habitat, because interactions among vegetation, soil, and hydrology within tidally restricted marshes prevent them from responding to sea level rise. Prediction of the tidal range that is expected after restoration relative to the current geomorphology is crucial for successful restoration of salt marsh habitat. Both insufficient (due to restriction) and excessive (due to subsidence and sea level rise) tidal flooding can lead to loss of salt marshes. We developed and applied the Marsh Response to Hydrological Modifications model as a predictive tool to forecast the success of management scenarios for restoring full tides to previously restricted areas. We present an overview of a computer simulation tool that evaluates potential culvert installations with output of expected tidal ranges, water discharges, and flood potentials. For three New England tidal marshes we show species distributions of plants for tidally restricted and nonrestricted areas. Elevation ranges of species are used for short‐term (<5 years) predictions of changes to salt marsh habitat after tidal restoration. In addition, elevation changes of the marsh substrate measured at these sites are extrapolated to predict long‐term (>5 years) changes in marsh geomorphology under restored tidal regimes. The resultant tidal regime should be designed to provide habitat requirements for salt marsh plants. At sites with substantial elevation losses a balance must be struck that stimulates elevation increases by improving sediment fluxes into marshes while establishing flooding regimes appropriate to sustain the desired plants.     

The murine CC chemokine, 6C-kine, inhibits tumor growth and angiogenesis in a human lung cancer SCID mouse model

The recently described CC chemokine, 6C-kine, is unique in that it contains -six rather than the usual four conserved cysteines typical of this family. Furthermore, murine 6C-kine binds to one of the CXC chemokine receptors CXCR3, in addition to its other known receptor CCR7. We have shown that two other ligands of CXCR3, IP-10 and MIG, are potent inhibitors of tumor growth in severe combined immunodeficiency (SCID) mice. We postulated that murine 6C-kine may also inhibit tumor growth via inhibition of angiogenesis in this model. SCID mice (n=6 per group) inoculated with A549 human lung cancer cells were treated with either 6C-kine (100 ng intra-tumor injection every other day) or control protein for 8 weeks. Tumors from murine 6C-kine-treated mice (288 ± 26 mm³) were significantly smaller than tumors from control treated mice (788 ± 156 mm³, P=0.005). Additionally, murine 6C-kine reduced metastases compared with controls (0.5 ± 0.3 vs 3.0 ± 1.2 metastases per animal, P=0.05). Tumor vascularity (as assessed by vessel density counting) was reduced in murine 6C-kine-treated mice compared with controls. Murine 6C-kine had no direct effect on proliferation of A549 cells, and there were no differences in the infiltration of leukocyte sub-populations, assessed by flow cytometry, in the treatment groups. Interestingly, human 6C-kine, unlike murine 6C-kine, does not bind CXCR3 and had no anti-tumor effect in the same model. These data suggest that murine 6C-kine has anti-tumor effects independent of its leukocyte-recruiting activity. Furthermore, while not confirmatory, these data lend further support to the fact that CXCR3 may be the receptor for angiostatic CXC chemokines. Received: 15 June 2000 / Accepted: 18 August 2000     

Differential expression of CC chemokines and the CCR5 receptor in the pancreas is associated with progression to type I diabetes

We investigated the biological role of CC chemokines in the Th1-mediated pathogenesis of spontaneous type I diabetes in nonobese diabetic (NOD) mice. Whereas an elevated ratio of macrophage inflammatory protein-1alpha (MIP-1alpha):MIP-1beta in the pancreas correlated with destructive insulitis and progression to diabetes in NOD mice, a decreased intrapancreatic MIP-1alpha:MIP-1beta ratio was observed in nonobese diabetes-resistant (NOR) mice. IL-4 treatment, which prevents diabetes in NOD mice by polarizing intraislet Th2 responses, decreased CCR5 expression in islets and potentiated a high ratio of MIP-1beta and monocyte chemotactic protein-1 (MCP-1): MIP-1alpha in the pancreas. Furthermore, NOD.MIP-1alpha-/- mice exhibited reduced destructive insulitis and were protected from diabetes. Neutralization of MIP-1alpha with specific Abs following transfer of diabetogenic T cells delayed the onset of diabetes in NOD.Scid recipients. These studies illustrate that the temporal expression of certain CC chemokines, particularly MIP-1alpha, and the CCR5 chemokine receptor in the pancreas is associated with the development of insulitis and spontaneous type I diabetes.     

Colon carcinoma cell glycolipids,integrins, and other glycoproteins mediate adhesion to HUVECs under flow

This study was undertaken toinvestigate the molecular constituents mediating LS174T colonadenocarcinoma cell adhesion to 4-h TNF--stimulated human umbilicalvein endothelial cells (HUVECs) under flow. At 1 dyn/cm²,~57% of cells rolled and then became firmly adherent, whereas otherscontinuously rolled on endothelium. Initial cell binding was primarilymediated by endothelial E-selectin. By using neuraminidase, glycolipidbiosynthesis inhibitord,l-threo-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol · HCl,trypsin, and flow cytometry, LS174T cells were shown to express sialylLewis^x (sLe^x)- anddi-sLe^x-decorated, but not sLe^a-decorated,glycolipid and glycoprotein ligands for E-selectin. The cellspreferentially employed sialylated glycoproteins over glycolipids inadhesion as measured by conversion of rolling to firm adhesion,resistance to detachment by increased shear stress, and rollingvelocity. However, a nonsialylated E-selectin counterreceptor alsoexists. Furthermore, LS174T ₂, ₆, and₁ integrins support a minor pathway in adhesion toHUVECs. Finally, tumor cell attachment specifically increases HUVECendocytosis of E-selectin. Altogether, the data indicate the complexityof carcinoma cell-endothelium adhesion via sialylated glycoconjugates,integrins, and their respective counterreceptors.

     

Controlled degradation and mechanical behavior of photopolymerized hyaluronic acid networks

Hyaluronic acid is a natural polysaccharide found abundantly throughout the body with many desirable properties for application as a biomaterial, including scaffolding for tissue engineering. In this work, hyaluronic acid with molecular weights ranging from 50 to 1100 kDa was modified with methacrylic anhydride and photopolymerized into networks with a wide range of physical properties. With macromer concentrations from 2 to 20 wt %, networks exhibited volumetric swelling ratios ranging from approximately 42 to 8, compressive moduli ranging from approximately 2 to over 100 kPa, and degradation times ranging from less than 1 day up to almost 38 days in the presence of 100 U/mL of hyaluronidase. When 3T3-fibroblasts were photoencapsulated in the hydrogels, cells remained viable with low macromer concentrations but decreased sequentially as the macromer concentration increased. Finally, auricular swine chondrocytes produced neocartilage when photoencapsulated in the hyaluronic acid networks. This work presents a next step toward the development of advanced in vivo curable biomaterials.