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Urban and peri-urban agriculture (UPA) significantly contributes to food and nutritional security of urban dwellers in many African countries. Economic and demographic pressures often lead to transformation of subsistence-oriented traditional homegardens into commercial production units. Such transformation is claimed to result in decreasing plant diversity, particularly of local species. A study was therefore undertaken in 51 gardens of Niamey, Niger, to assess the factors determining plant diversity and the suitability of UPA for in situ conservation of plant genetic resources. In each garden, the number and abundance of all human-used plant species were determined, and species density, Shannon index and Shannon evenness were calculated. In the 51 surveyed gardens, a total of 116 plant species were cultivated, most of them for the production of fruits or vegetables. Annual vegetables dominated, particularly exotic species grown for sale. In the cold season, an average of 14 species were cultivated per garden, the Shannon index was 0.96 and evenness was 0.39. Commercial gardens had a species richness similar to that of subsistence gardens, but a lower evenness (P < 0.005), caused by the dominance of a few vegetable species. Gardens of immigrants had a lower Shannon index than those of members of the local Djerma ethnic group. Stepwise multiple regression analysis showed significant influence of various variables on plant species richness and diversity parameters: garden size (richness and Shannon index), ethnicity of the gardener (richness and evenness), gender of the gardener and cash-oriented production (evenness), household size (richness) and garden possession status (Shannon index). Cluster analysis revealed the existence of five garden types. The highest species richness and diversity, particularly of perennial and local species, was found in large, peri-urban, commercial gardens managed by relatively wealthy, elderly gardeners with large families and a regular non-agricultural income.  相似文献   
33.
The flavonoid pattern of an acetonic extract of Grindelia robusta Nutt. was investigated in detail. The flavonoids were enriched by CC. In addition to twelve known methylated exudate flavonols four compounds were identified for the first time in G. robusta. Several substances of the flavonoid complex, among them the main compounds quercetin-3-methylether and 6-OH-kaempferol-3,6-dimethylether, were tested for their activity to inhibit neutrophil elastase. Quercetin-3-methylether was shown to be most active with an IC50 of 19 µM, thus obviously contributing to the anti-inflammatory activity of the drug.  相似文献   
34.
Menopause-associated thermoregulatory dysfunction can lead to symptoms such as hot flushes severely impairing quality of life of affected women. Treatment effects are often assessed by the ovariectomized rat model providing time series of tail skin temperature measurements in which circadian rhythms are a fundamental ingredient. In this work, a new statistical strategy is presented for analyzing such stochastic-dynamic data with the aim of detecting successful drugs in hot flush treatment. The circadian component is represented by a nonlinear dynamical system which is defined by the van der Pol equation and provides well-interpretable model parameters. Results regarding the statistical evaluation of these parameters are presented.  相似文献   
35.
Homegardens are traditional food systems that have been adapted over generations to fit local cultural and ecological conditions. They provide a year-round diversity of nutritious foods for smallholder farming communities in many regions of the tropics and subtropics. In southwestern Uganda, homegardens are the primary source of food, providing a diverse diet for rural marginalized poor. However, national agricultural development plans as well as economic and social pressures threaten the functioning of these homegardens. The implications of these threats are difficult to evaluate, because the structure and functions of the homegardens are not well understood. The aim of the study was to identify patterns and influencing factors in the diversity of homegardens by documenting the floristic diversity and its interactions with spatial, environmental and socio-economic factors. A geographically and socially focused assessment of floristic diversity in 102 randomly selected homegardens in three districts of southwest Uganda was conducted along a deforestation gradient following a human ecology conceptual framework and testing multiple quantitative hypotheses regarding the above mentioned factors. A merged mixed-method approach was followed to provide context and feedback regarding quantitative findings. Results show a high total richness of 209 (mean 26.8 per homegarden) crop species (excluding weeds and ornamentals) dominated by food species, which constituted 96 percent of individuals and 44 percent of all species. Forest-edge homegardens maintained higher plant diversity compared to homegardens in deforested areas and near degraded wetlands. Multiple linear regression models indicated elevation, location, homegarden size, distance to market, additional land ownership (outside the homegarden) and livestock ownership as significant predictors of crop diversity. Cluster analysis of species densities revealed four garden types: ‘diverse tree gardens’, ‘small forest-edge gardens’, ‘large, old, species-rich gardens’, and ‘large, annual-dominated herb gardens’, with 98% correct classification. Location, elevation, and garden size were also important determinants in the cluster assignment. We conclude that the diversity of the studied homegardens may be changing as part of adaptive traditional practices and in response to external drivers. The identified patterns illustrate the importance of homegardens for rural livelihoods and may offer some ways to support farmers to maintain these systems as relevant mechanisms for development in Uganda.  相似文献   
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The differentiation of nonrefined (e.g., cold-pressed) and refined edible oils is an important task in food control because of the higher commercial value of the former. Here, we explored the suitability of the relative abundance of cis-phytol as a marker for authentication of nonrefined edible oils. Phytol, the tetramethyl-branched, monoenoic alcohol, is found widespread in nature as a part of chlorophyll. In chlorophyll, only trans-phytol is found. In this study, we present a method for the analysis of the phytol isomers, considering that traces of cis-phytol (contributing 0.1% to the phytol content) can be determined next to trans-phytol. For this purpose, phytol was gathered with the unsaponifiable matter from the oil, trimethylsilylated, and analyzed by gas chromatography coupled to mass spectrometry. With this method, 27 samples of edible oils (16 refined and 11 nonrefined edible oils) were analyzed for the abundance of cis-phytol relative to trans-phytol. In the nonrefined oils (e.g., olive oil, rapeseed oil, maize oil, and sunflower oil), cis-phytol contributed 0.1% (n = 3) or less (n = 8) to the phytol content. In contrast, the refined olive oils (n = 4) contained a share of 1.3-3% cis-phytol; the refined rapeseed oil (n = 3) contained a share of 0.7-1.0% cis-phytol; and the refined sunflower oil (n = 4) contained a share of 0.3-0.9% cis-phytol. Only one refined pomegranate kernel did not contain cis-phytol. The phytol concentration was not suited to distinguish nonrefined from refined oils. In contrast, our data suggest that the virtual absence of cis-phytol can be used as a marker for nonrefined (e.g., cold-pressed) edible oils.  相似文献   
38.
Inhalation of vanadium pentoxide clearly increases the incidence of alveolar/bronchiolar neoplasms in male and female B6C3F1 mice at all concentrations tested (1, 2 or 4 mg/m3), whereas responses in F344/N rats was, at most, ambiguous. While vanadium pentoxide is mutagenic in vitro and possibly in vivo in mice, this does not explain the species or site specificity of the neoplastic response. A nose-only inhalation study was conducted in female B6C3F1 mice (0, 0.25, 1 and 4 mg/m3, 6 h/day for 16 days) to explore histopathological, biochemical (α-tocopherol, glutathione and F2-isoprostane) and genetic (comet assays and 9 specific DNA-oxo-adducts) changes in the lungs. No treatment related histopathology was observed at 0.25 mg/m3. At 1 and 4 mg/m3, exposure-dependent increases were observed in lung weight, alveolar histiocytosis, sub-acute alveolitis and/or granulocytic infiltration and a generally time-dependent increased cell proliferation rate of histiocytes. Glutathione was slightly increased, whereas there were no consistent changes in α-tocopherol or 8-isoprostane F2α. There was no evidence for DNA strand breakage in lung or BAL cells, but there was an increase in 8-oxodGuo DNA lesions that could have been due to vanadium pentoxide induction of the lesions or inhibition of repair of spontaneous lesions. Thus, earlier reports of histopathological changes in the lungs after inhalation of vanadium pentoxide were confirmed, but no evidence has yet emerged for a genotoxic mode of action. Evidence is weak for oxidative stress playing any role in lung carcinogenesis at the lowest effective concentrations of vanadium pentoxide.  相似文献   
39.
In this study, we identified and quantitated a tetrachlorinated compound found at high concentrations in some samples of the meat of free-ranging wild boar (Sus scrofa) from Southern Germany. Mass spectrometric analysis indicated that the compound was a tetrachloromethoxyphenol isomer, and the subsequently synthesized tetrachloro-p-methoxyphenol was identical with the unknown compound in wild boar. Tetrachloro-p-methoxyphenol is a known secondary metabolite of basidiomycetous fungi, which in turn are regular feed items of the wild boar. It is extremely likely that the wild boar have accumulated tetrachloro-p-methoxyphenol by exploiting basidiomycetes. The highest concentration in the samples (n = 22) was ~1 mg/kg lipids tetrachloro-p-methoxyphenol. This concentration was higher than that of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) in any of the samples. Some samples did not contain tetrachloro-p-methoxyphenol, which indicates varied preferences in fungi by wild boars. Our data suggest that during their entire evolution, humans have been in contact with the natural product tetrachloro-p-methoxyphenol by consuming wild boars.  相似文献   
40.

Background

In dogs, increasing the tissue n-3 fatty acid (FA) content is associated with potential benefit in some medical conditions, e.g. atopic dermatitis, cancer or heart disease. Therefore effectively and conveniently increasing tissue n-3 FA levels in dogs is of interest. Incorporation of dietary n-3 FA into cell membranes may be studied by FA analysis of erythrocyte membranes (EM), because of the correlation of its FA composition with the FA composition of other cells. Aim of the study was to determine whether an n-3 FA additive added to a control diet is as effective in increasing EM n-3 FA content as feeding an n-3 FA enriched diet. Furthermore the time course of the incorporation of dietary n-3 FA into canine EM was investigated.

Methods

Thirty dogs were randomly divided into three dietary groups with ten dogs per group. CONT got a dry dog food diet which did not contain EPA or DHA. FO got a dry dog food diet with a high EPA and DHA content. ADD got the CONT diet combined with an n-3 FA additive rich in DHA and EPA. After a feeding period of 12 weeks the additive was discontinued in ADD and these dogs were fed CONT diet for another four weeks to observe washout effects. Erythrocyte lipids were extracted from venous blood samples and their FA composition was determined by gas chromatography. The Mann-Whitney-U-test was used to detect significant differences between the different groups and time points.

Results

After one week the proportions of n-3 FA, DHA and EPA were already significantly increased in ADD and FO, apparently reaching a plateau within eight weeks. In our study DHA and not EPA was preferably incorporated into the EM. After discontinuing the administration of the additive in ADD, the n-3 FA values declined slowly without reaching baseline levels within four weeks.

Conclusions

In dogs, an increase of dietary n-3 FA content leads to a rapid inclusion of n-3 FA into EM, regardless of whether the n-3 FA are offered as an enriched diet or as a normal diet supplemented with an n-3 FA additive.  相似文献   
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