533 research outputs found

    Bone quality assessment of osteogenic cell cultures by Raman microscopy

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    The use of autologous stem/progenitor cells represents a promising approach to the repair of craniofacial bone defects. The calvarium is recognized as a viable source of stem/progenitor cells that can be transplanted in vitro to form bone. However, it is unclear if bone formed in cell culture is similar in quality to that found in native bone. In this study, the quality of bone mineral formed in osteogenic cell cultures were compared against calvarial bone from postnatal mice. Given the spectroscopic resemblance that exists between cell and collagen spectra, the feasibility of extracting information on cell activity and bone matrix quality were also examined. Stem/progenitor cells isolated from fetal mouse calvaria were cultured onto fused‐quartz slides under osteogenic differentiation conditions for 28 days. At specific time intervals, slides were removed and analyzed by Raman microscopy and mineral staining techniques. We show that bone formed in culture at Day 28 resembled calvarial bone from 1‐day‐old postnatal mice with comparable mineralization, mineral crystallinity, and collagen crosslinks ratios. In contrast, bone formed at Day 28 contained a lower degree of ordered collagen fibrils compared with 1‐day‐old postnatal bone. Taken together, bone formed in osteogenic cell culture exhibited progressive matrix maturation and mineralization but could not fully replicate the high degree of collagen fibril order found in native bone.In this Raman spectroscopic study, we examined the quality of bone formed in vitro by fetal mouse calvarial stem/progenitor cells under osteogenic differentiation conditions. We characterized bone mineral and matrix cell culture components and detected the presence of lipid and glycosaminoglycan‐like components. Bone formed in vitro at Day 28 was similar to 1‐day‐old postnatal mouse calvarial bone in terms of mineralization, mineral crystallinity, and collagen crosslink ratios, but differed in the degree of collagen fibril order.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148347/1/jrs5521_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148347/2/jrs5521.pd

    Hydrological Foundation as a Basis for a Holistic Environmental Flow Assessment of Tropical Highland Rivers in Ethiopia

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    The sustainable development of water resources includes retaining some amount of the natural flow regime in water bodies to protect and maintain aquatic ecosystem health and the human livelihoods and wellbeing dependent upon them. Although assessment of environmental flows is now occurring globally, limited studies have been carried out in the Ethiopian highlands, especially studies to understand flow-ecological response relationships. This paper establishes a hydrological foundation of Gumara River from an ecological perspective. The data analysis followed three steps: first, determination of the current flow regime flow indices and ecologically relevant flow regime; second, naturalization of the current flow regime looking at how flow regime is changing; and, finally, an initial exploration of flow linkages with ecological processes. Flow data of Gumara River from 1973 to 2018 are used for the analysis. Monthly low flow occurred from December to June; the lowest being in March, with a median flow of 4.0 m(3) s(-1). Monthly high flow occurred from July to November; the highest being in August, with a median flow of 236 m(3) s(-1). 1-Day low flows decreased from 1.55 m(3) s(-1) in 1973 to 0.16 m(3) s(-1) in 2018, and 90-Day (seasonal) low flow decreased from 4.9 m(3) s(-1) in 1973 to 2.04 m(3) s(-1) in 2018. The Mann-Kendall trend test indicated that the decrease in low flow was significant for both durations at alpha = 0.05. A similar trend is indicated for both durations of high flow. The decrease in both low flows and high flows is attributed to the expansion of pump irrigation by 29 km(2) and expansion of plantations, which resulted in an increase of NDVI from 0.25 in 2000 to 0.29 in 2019. In addition, an analysis of environmental flow components revealed that only four "large floods" appeared in the last 46 years; no "large flood" occurred after 1988. Lacking "large floods" which inundate floodplain wetlands has resulted in early disconnection of floodplain wetlands from the river and the lake; which has impacts on breeding and nursery habitat shrinkage for migratory fish species in Lake Tana. On the other hand, the extreme decrease in "low flow" components has impacts on pin smaller pools. These results serve as the hydrological foundation for continued studies in the Gumara catchment, with the eventual goal of quantifying environmental flow requirements.redators, reducing their mobility and ability to access prey concentrate

    Process evaluation of two environmental nutrition programmes and an educational nutrition programme conducted at supermarkets and worksite cafeterias in the Netherlands

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    This article describes the process evaluation of two environmental programs and a educational nutrition program, implemented at supermarkets and worksite cafeterias. Studies conducted earlier, indicated that the programs had no effect on consumers’ eating behavior. Consequently, the more specific purpose of the present study was to identify explanations for the ineffectiveness of the programs and to formulate recommendations for future programs. Materials and Methods The environmental programs included labeling of healthy products and increasing the range of healthy foods on offer. The education program consisted of several elements, such as brochures and a self-help guide. Semi-structured interviews were conducted with twenty-one managers of supermarkets and worksite cafeterias where the programs were implemented. Results Although materials were not always entirely compatible with the different supermarkets and worksite cafeterias, the degree of implementation was satisfactory. According to the managers, the programs were not striking enough, the labeling would have been more effective if it had discriminated between different brands of a product, and the number of new products was too small compared to the total range of foods on offer. Discussion The results can be used to help design and check future intervention programs for use at supermarkets or worksite cafeterias. Recommendations for future programs and research are given

    Impact of small-scale irrigation schemes on household income and the likelihood of poverty in the Lake Tana basin of Ethiopia

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    This study uses Tobit and Logit models to examine the impacts of selected small-scale irrigation schemes in the Lake Tana basin of Ethiopia on household income and the likelihood of poverty, respectively. Data for these analyses were collected from a sample of 180 households. Households using any of the four irrigation systems had statistically significantly higher mean total gross household income than households not using irrigation. The marginal impact of small-scale irrigation on gross household income indicated that each small scale-irrigation user increased mean annual household income by ETB 3353 per year, a 27% increase over income for non-irrigating households. A Logit regression model indicated that access to irrigation significantly reduced the odds that a household would be in the lowest quartile of household income, the poverty threshold used in this study. Households using concrete canal river diversion had higher mean cropping income per household than those using other irrigation types. Key challenges to further enhancing the benefits of irrigation in the region include water seepage, equity of water distribution, availability of irrigation equipment, marketing of irrigated crops and crop diseases facilitated by irrigation practices

    Infrared spectroscopic identification of the C–O stretching vibration associated with the tyrosyl Z⋅ and D⋅ radicals in photosystem II2Supported by NIH GM 43272 (B.A.B.), NSF MCB 94-18164 (B.A.B.), a graduate minority supplement to NIH GM 43273 (I.A.), a graduate fellowship from Committee on Institutional Cooperation, University of Minnesota (I.A.), and a summer research fellowship from Dupont, Central Research and Development, administered through the University of Minnesota (E.T.G.).2

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    AbstractPhotosystem II (PSII) is a multisubunit complex, which catalyzes the photo-induced oxidation of water and reduction of plastoquinone. Difference Fourier-transform infrared (FT-IR) spectroscopy can be used to obtain information about the structural changes accompanying oxidation of the redox-active tyrosines, D and Z, in PSII. The focus of our work is the assignment of the 1478 cm−1 vibration, which is observable in difference infrared spectra associated with these tyrosyl radicals. The first set of FT-IR experiments is performed with continuous illumination. Use of cyanobacterial strains, in which isotopomers of tyrosine have been incorporated, supports the assignment of a positive 1478/1477 cm−1 mode to the C–O stretching vibration of the tyrosyl radicals. In negative controls, the intensity of this spectral feature decreases. The negative controls involve the use of inhibitors or site-directed mutants, in which the oxidation of Z or D is eliminated, respectively. The assignment of the 1478/1477 cm−1 vibrational mode is also based on control EPR and fluorescence measurements, which demonstrate that no detectable Fe2+QA− signal is generated under FT-IR experimental conditions. Additionally, the difference infrared spectrum, associated with formation of the S2QA− state, argues against the assignment of the positive 1478 cm−1 line to the C–O vibration of QA−. In the second set of FT-IR experiments, single turnover flashes are employed, and infrared difference spectra are recorded as a function of time after photoexcitation. Comparison to kinetic transients generated in control EPR experiments shows that the decay of the 1477 cm−1 line precisely parallels the decay of the D⋅ EPR signal. Taken together, these two experimental approaches strongly support the assignment of a component of the 1478/1477 cm−1 vibrational lines to the C–O stretching modes of tyrosyl radicals in PSII. Possible reasons for the apparently contradictory results of Hienerwadel et al. (Biochemistry 35 (1996) 15447–15460 and Biochemistry 36 (1997) 14705–14711) are discussed

    Evaluation of CFSR, TMPA 3B42 and ground-based rainfall data as input for hydrological models, in data-scarce regions: The upper Blue Nile Basin, Ethiopia

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    Accurate prediction of hydrological models requires accurate spatial and temporal distribution of rainfall. In developing countries, the network of observation stations for rainfall is sparse and unevenly distributed. Satellite-based products have the potential to overcome this shortcoming. The objective of this study is to compare the advantages and the limitation of commonly used high-resolution satellite rainfall products (Climate Forecast System Reanalysis (CFSR) and Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) 3B42 version 7) as input to hydrological models as compared to sparsely and densely populated network of rain gauges. We used two (semi-distributed) hydrological models that performed well in the Ethiopian highlands: Hydrologiska Byråns Vattenbalansavdelning (HBV) and Parameter Efficient Distributed (PED). The rainfall products were tested in two watersheds: Gilgel Abay with a relatively dense network of rain gauge stations and Main Beles with a relatively scarce network, both are located in the Upper Blue Nile Basin. The results indicated that TMPA 3B42 was not be able to capture the gauged rainfall temporal variation in both watersheds and was not tested further. CFSR over predicted the rainfall pattern slightly. Both the gauged and the CFSR reanalysis data were able to reproduce the streamflow well for both models and both watershed when calibrated separately to the discharge data. Using the calibrated model parameters of gauged rainfall dataset together with the CFSR rainfall, the stream discharge for the Gilgel Abay was reproduced well but the discharge of the Main Beles was captured poorly partly because of the poor accuracy of the gauged rainfall dataset with none of the rainfall stations located inside the watershed. HBV model performed slightly better than the PED model, but the parameter values of the PED could be identified with the features of the landscape

    Improved water and land management in the Ethiopian highlands and its impact on downstream stakeholders dependent on the Blue Nile

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    Improved water and land management in the Ethiopian highlands and its impact on downstream stakeholders dependent on the Blue Nile – short title Upstream-Downstream in Blue Nile River project is one of the projects in the Nile Basin supported by the CPWF. It was implemented during from 2007 to 2009 through a partnership of 8 institutions. The Blue Nile is the major tributary of the Nile River, contributing about 62% of the Nile flow at Aswan. About two thirds of the area of this densely populated basin is in the highlands and hence receives fairly high levels of annual rainfall of 800 to 2,200 mm. However, the rainfall is erratic in terms of both spatial and temporal distribution with prolonged dry spells and drought often leading to crop failures. Currently, water resources are only marginally exploited in the upper basin but are much more developed in the downstream reaches. The population, located in the downstream part of the Blue Nile, is dependent on the river water for supplementary irrigation and energy production. Canal and reservoir siltation is a major problem, adding the burdens of poor riparian farmers. This project was envisaged to improve the scientific understanding of the land and water resources of the basin, and hypothesized that with increased scientific knowledge of the hydrological, watershed, and institutional processes of the Blue Nile in Ethiopia (Abbay), constraints to up-scaling adaptable best practices and promising technologies (technical, socio-economic, institutional) could be overcome, which will result in significant positive impacts for both upstream and downstream communities and state
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