How effective is community-based management of freshwater resources? A review.

Despite the existence of numerous research studies on community-based conservation, relatively few focus on the particularities of freshwater ecosystems. Freshwater ecosystems are distinct from terrestrial and marine ecosystems, exhibiting both greater concentrations of biodiversity and elevated threats. In addition, freshwater resources have distinct social, legal, political, and economic characteristics which limit the generalizability of community-based conservation research from other ecological domains. We examine peer-reviewed literature on community-based management of freshwater resources to understand and assess project contexts and outcomes. Our review indicates that studies of freshwater community-based management are limited in number and representativeness. While positive outcomes for both biodiversity and human well-being are commonly reported, limitations due to study design constrain the ability to infer the significance or causality of these effects. Overall, our analysis indicates that there are several gaps in the available research: across geographic regions, freshwater ecosystem types, intervention types, and environmental and human well-being outcome types. Given the importance of freshwater resources to Indigenous Peoples and local communities, our review highlights the critical need to generate evidence across more diverse contexts to achieve greater clarity on whether and how community-based projects can be most effective.

Opportunities for natural infrastructure to improve urban water security in Latin America.

Governments, development banks, corporations, and nonprofits are increasingly considering the potential contribution of watershed conservation activities to secure clean water for cities and to reduce flood risk. These organizations, however, often lack decision-relevant, initial screening information across multiple cities to identify which specific city-watershed combinations present not only water-related risks but also potentially attractive opportunities for mitigation via natural infrastructure approaches. To address this need, this paper presents a novel methodology for a continental assessment of the potential for watershed conservation activities to improve surface drinking water quality and mitigate riverine and stormwater flood risks in 70 major cities across Latin America. We used publicly available geospatial data to analyze 887 associated watersheds. Water quality metrics assessed the potential for agricultural practices, afforestation, riparian buffers, and forest conservation to mitigate sediment and phosphorus loads. Flood reduction metrics analyzed the role of increasing infiltration, restoring riparian wetlands, and reducing connected impervious surface to mitigate riverine and stormwater floods for exposed urban populations. Cities were then categorized based on relative opportunity potential to reduce identified risks through watershed conservation activities. We find high opportunities for watershed activities to mitigate at least one of the risks in 42 cities, potentially benefiting 96 million people or around 60% of the urbanites living in the 70 largest cities in Latin America. We estimate water quality could be improved for 72 million people in 27 cities, riverine flood risk mitigated for 5 million people in 13 cities, and stormwater flooding mitigated for 44 million people in 14 cities. We identified five cities with the potential to simultaneously enhance water quality and mitigate flood risks, and in contrast, six cities where conservation efforts are unlikely to meaningfully mitigate either risk. Institutions investing in natural infrastructure to improve water security in Latin America can maximize their impact by focusing on specific watershed conservation activities either for cleaner drinking water or flood mitigation in cities identified in our analysis where these interventions are most likely to reduce risk.

Collagen extracts derived from young and aged mice demonstrate different structural properties and cellular effects in three-dimensional gels.

Three-dimensional (3D) type I collagen gels are increasingly utilized to simulate extracellular matrix (ECM) in vivo, but little is known about the effects of age on this model. Collagen was extracted from young (4-6 months) and aged (20-24 months) mice tails and compared. The collagens appeared similar by electrophoresis. However, relative to young, aged collagen formed fibrils slower and generated 3D gels with smaller diameter, less dense fibrils (75 vs 34 nm diameter and 8 vs 3.5% area, for young and aged respectively, p < 0.02). Correspondingly, aged collagen gels were more malleable and contractible (5% vs 19% compression, p < .02, and 73% vs 15.5% area, p < .01, for young and aged, respectively). Fibroblasts cultured within young and aged collagen gels had differential expression of a limited number of genes and proteins corresponding to specific integrins and matrix components. In summary, collagen extracted from young and aged mice is an effective means to examine the influence of aging on functional properties of ECM that are relevant in vivo.

Nitric oxide effects on the function of aged cells ex vivo and in vivo.

BACKGROUND: Angiogenesis is impaired in most aged tissues. Accordingly, there is great interest in interventions that improve the ability of aged cells to undergo blood vessel formation and subsequent tissue repair. MATERIALS AND METHODS: Nitric oxide (NO), a mediator proposed to enhance angiogenesis, was administered (as the precursor SNAP, S-nitroso-N-acetylpenicillamine) to aortic ring explants from aged mice and to aged mice in two separate in vivo experiments: a PVA sponge implant model of angiogenesis and full thickness excisional dermal wounds. RESULTS: SNAP inhibited angiogenesis from the mouse aortic ring explants. However, there was a trend toward increased blood vessel formation in the sponges from the aged mice treated with SNAP. SNAP did not detectably enhance dermal wound healing or angiogenesis, but it significantly inhibited epidermal closure. CONCLUSION: These data underscore the complexity of using a single agent, even one with multiple mechanisms such as NO, to improve a clinical outcome such as angiogenesis or wound repair in aged animals.

Endothelial precursor cells.

The discovery and subsequent characterization of endothelial precursor cells (EPCs) has stimulated interest in their potential use in older persons. Understanding the mechanisms that underlie EPC availability and function has important clinical implications for this age group. In this review, we discuss aspects of EPCs that are relevant to their role in angiogenesis and cardiovascular disease. We then review the limited data on features of EPCs that are known to be altered in aging and might better define their clinical utility in older persons.

Culture of murine aortic explants in 3-dimensional extracellular matrix: a novel, miniaturized assay of angiogenesis in vitro.

Assays of angiogenesis in vitro are critical to the study of vascular morphogenesis and to the evaluation of therapeutic compounds that promote or inhibit vascular growth. Culture of explanted aortic segments from rats or mice in a 3-dimensional extracellular matrix (ECM) is one of the most effective ways to generate capillary-like endothelial sprouts in vitro. We have modified the classic aortic explant model by placing the aortic segments from mice within small (5.6 mm diameter, 30 microl volume) lenticular hydrogels of type I collagen supported at the edge by nylon mesh rings. This method of culture, referred to as the "miniature ring-supported gel" (MRSG) assay, optimizes handling, cytological staining, and conventional imaging of the specimen and permits use of minimal volumes of reagents in a 96-well tissue culture format. We have used the MRSG assay to quantify the impaired angiogenic response of aged mice relative to young mice and to show that aged mice have significantly decreased sprout formation, but have similar levels of invasion of vascular smooth muscle cells into the supportive ECM. The MRSG assay, which combines low volume, physically robust gels in conjunction with mouse aortic segments, may prove to be a highly useful tool in studies of the process and control of vascular growth.

The effects of aging on tumor growth and angiogenesis are tumor-cell dependent.

It is generally accepted that histologically similar tumors grow more slowly, with less angiogenesis, in aged mice relative to young mice. We subcutaneously implanted TRAMP-C2 tumor cells, a prostate cancer cell line not previously examined in aging, into syngeneic C57/Bl6 young (4 month) and aged (20 month) mice and compared tumor growth and angiogenesis. Unexpectedly, the prostate tumors grew as fast in aged as in young mice. Angiogenesis in TRAMP-C2 tumors was robust, with no differences between the young and aged mice in the number of vessels, distribution of vessel sizes or features of vessel maturation. Aged mice had lower levels of serum testosterone than the young mice. VEGF levels were similar in the tumors and sera of the young and aged mice. Comparison with B16/F10 melanoma, a cancer cell line that is representative of previous studies in aged mice, showed that B16/F10 tumors grew minimally in the aged mice. In contrast to the B16/F10, TRAMP-C2 tumors had an extracellular matrix with significantly higher levels of MMP2 and MMP9 expression and activity. These unique results demonstrate that tumor progression can be as robust in aged tissues as young tissues. The ability of aged mice to grow large, vascularized prostate tumors is associated with high levels of MMP2/9 activity that may produce a permissive environment for tumor growth and angiogenesis. These data demonstrate that tumor-cell specific features determine the effect of aging on tumor growth and angiogenesis.

Age-related differences in repair of dermal wounds and myocardial infarcts attenuate during the later stages of healing.

BACKGROUND: It is unclear whether delays in wound repair due to the age of the host persist into the later stages of healing. Late stage healing of dermal wounds and myocardial infarcts in rodents was examined to determine if aged animals "catch up" to their younger counterparts. MATERIALS AND METHODS: Excisional dermal wounds (5 mm) were made by punch biopsy and myocardial infarctions were produced by ligation of the left anterior descending coronary artery in young and aged mice and rats, respectively. Dermal wounds at day 11 and myocardial infarctions at day 14 were analyzed for wound area, angiogenesis, deposition of basement membrane proteins, and remodeling of collagen. RESULTS: Analyses demonstrated that wound areas, the deposition of basement membrane proteins and angiogenic responses were similar in young and aged rodents at late stages of wound repair. The dermal wounds of young mice had larger quantities of mature, compacted collagen fibers relative to aged mice, but immature collagen fibers predominated in myocardial infarcts in both young and aged rats. CONCLUSION: These results show that, with the exception of dermal collagen remodeling, aged animals catch up to their young counterparts with respect to many features of tissue repair. Consequently, therapies that target age-related deficiencies in healing will be most effective when administered shortly after the initial insult.