Effect of the citrus flavanone naringenin on oxidative stress in rats

Flavonoids are non-nutrient plant phenolic compounds proposed to provide health benefits in humans. The antioxidant and prooxidant effects of the citrus flavanone naringenin have been tested only in vitro. The dose-response effect of naringenin consumption was tested in weanling rats (n=6-8/group) with a 2x4 factorial design using high or low oxidative stress (Hox or Lox, respectively) diets, created by adequate or deficient amounts of vitamin E and selenium, with three increasing naringenin concentrations (30, 60, or 120 mg/kg of diet). Hox compared to Lox rats exhibited reduced growth and liver hypertrophy, which was not prevented by naringenin consumption. Also, Hox rats exhibited severalfold higher liver NAD(P)H:quinone oxidoreductase-1 activity, which was further elevated in proportion to naringenin intake, but this was not sufficient to protect against oxidative stress indicated by higher liver total aldehydes. In addition, dietary naringenin did not affect antioxidant nutrient status or physiological markers of growth under Lox conditions. Thus, dietary naringenin did not exhibit antioxidant or prooxidant effects in vivo in this rat model.     

The methylmercury to total mercury ratio in selected marine,freshwater, and terrestrial organisms

Total and methylmercury concentrations were determined in muscle and organ tissue from a wide variety of marine and terrestrial organisms spanning several trophic levels. Sediment and water samples from many of the tissue sampling sites were also analyzed to assess the degree of mercury contamination to which the animals were exposed. The methylmercury to total mercury ratios were examined to determine whether this ratio is indicative of elevated exposure to organic or inorganic mercury and how it varies relative to tissue type and position in the food chain. As an ancillary study, a subset of these tissues was analyzed as 1) wet tissue, and 2) freeze-dried, ball-milled tissue to determine whether the form of sample preparation can adversely affect mercury analysis. Results indicate that the methylmercury to total mercury ratios generally approach unity only in muscle tissue of higher food chain carnivorous fish residing in waters that are relatively uncontaminated with respect to inorganic mercury species. Herbivorous terrestrial mammals and low food chain marine organisms tend to have very low methylmercury to total mercury ratios. Marine animals placed higher on the food chain, such as crabs and lobsters, exhibit somewhat higher methylmercury to total mercury ratios and can exhibit a large variation in this ratio between, organ tissue and muscle tissue of the same animal. The samples analyzed as both wet and freeze-dried, ball-milled tissue indicate that freezedrying and ball-milling in no way result in mercury loss or contamination and, in fact, result in better replicate analyses and create a sample sufficiently stable to be archived for several years without refrigeration.     

Oxidative Stress, the Paradigm of Ozone Toxicity in Plants and Animals

Tropospheric ozone represents a relevant atmospheric pollutant, because of its strong oxidizing potential. The risk for animal (human) and plant health, at molecular and cellular level, arises from the oxidative damage to lipids, proteins and nucleic acids, depending on the dose. Therefore, ozone concentration and exposure time determine the chronic or acute toxicity and, consequently, the severity of injury at biochemical and physiological level. In living organisms, reactive oxygen species (ROS), directly or indirectly derived from ozone exposure, are scavenged by enzymatic and non-enzymatic antioxidant defensive mechanisms, overall deputed to preserve cell structures and biomacromolecules from the oxidative damage. These defences are essentially those also involved in detoxifying the ROS inevitably produced by the metabolism of organisms living in oxygenic atmosphere.     

Impacts of tourism on anxiety and physiological stress levels in wild male Barbary macaques

Wildlife tourism is a burgeoning global industry with the potential to make a significant contribution to the conservation of endangered species. However, a number of studies have provided evidence that tourists’ presence and behaviour may impact negatively on the animals involved, with potentially harmful consequences for their health, reproduction and population viability. Here, we investigate impacts of tourism on wild male Barbary macaques (Macaca sylvanus) in Morocco, quantifying a behavioural index of animals’ anxiety (self-scratching) and a measure of their physiological stress levels (faecal glucocorticoid concentrations – FGCs). Four measures of tourist presence, number or proximity were explored: maximum number, percentage of time present, mean number while present, and closest proximity to the macaques. In addition, rates of three types of interactions between tourists and macaques – neutral (e.g. photographing), feeding and aggressive – were quantified. Males’ rates of self-scratching were positively related to the mean number of tourists present and to rates of all three human-macaque interactions, but were unrelated to the other three measures of tourist pressure. FGCs were positively related to rates of aggressive interactions between humans and macaques, but unrelated to any of the other six measures of tourist pressure. These findings suggest that while tourist presence and interactions (even apparently innocuous ones) with the macaques elevate the study animals’ anxiety levels, only aggressive interactions are sufficient to elicit a detectable increase in our measure of physiological stress. These results can be used to inform management of tourism both at this site, and at other locations where tourists view and can interact with wild primates.     

Modulation of the ROS‐scavenging system in salt‐stressed wheat plants inoculated with arbuscular mycorrhizal fungi

Although there is evidence for a positive involvement of the antioxidant defense system in plant response to salt stress, there is poor information regarding the influence of mycorrhizal symbiosis on enzymatic and nonenzymatic antioxidant defense in wheat under saline conditions. The present article focuses on the contribution of mycorrhizae to antioxidant defense in salt‐stressed wheat plants. Two wheat (Triticum aestivum L.) cultivars, Sids 1 and Giza 168, were grown under nonsaline or two saline conditions (4.7 and 9.4 dS m^–1) with and without arbuscular mycorrhizal fungi (AMF) inoculation. Salt stress considerably decreased root colonization and plant productivity, particularly in Giza 168. Interestingly, mycorrhizal colonization alleviated the adverse effect of salt stress and significantly enhanced plant productivity, especially in Sids 1. The concentration of glycinebetaine, the activities of antioxidative enzymes (superoxide dismutase, peroxidase, catalase, and glutathione reductase) and the concentrations of antioxidant molecules (glutathione and ascorbate) were increased under saline conditions; these increases were more significant in salt‐stressed mycorrhizal plants, especially in Sids 1. Salt stress induced oxidative damage through increased lipid peroxidation, electrolyte leakage, and hydrogen peroxide concentration, particularly in Giza 168. Mycorrhizal colonization altered plant physiology and significantly reduced oxidative damage. Elimination of reactive oxygen species (ROS) can be one of the mechanisms how AMF improve wheat adaptation to saline soils and increase its productivity.     

Exposure to tourism reduces stress-induced corticosterone levels in Galápagos marine iguanas

Unstressed and stress-induced plasma corticosterone levels in Galápagos marine iguanas (Amblyrhynchus cristatus) were compared in animals from a site heavily exposed to tourism to animals from a site undisturbed by humans. Initial corticosterone levels not only did not differ between the two groups, but they were 50% of levels in iguanas known to be chronically stressed. These data suggest that iguanas in tourist areas are not chronically stressed. Both groups of iguanas exhibited elevated corticosterone levels after 30 min of capture and restraint, indicating that they can physiologically respond to stressful stimuli. The stress response was lower, however, at the tourist site. This result indicates that iguanas are physiologically affected by tourism, although it is presently unknown whether these changes are ultimately beneficial or harmful.     

Melatonin alleviates cold‐induced oxidative damage in maize seedlings by up‐regulating mineral elements and enhancing antioxidant activity

Melatonin, known as an animal hormone and an antioxidant with a low molecular weight, is one of the most commonly used substances to improve plant resistance against various environmental stresses. However, there are no studies explaining the effects of melatonin on the relationship between defense system and mineral composition of plants under stressed and unstressed‐conditions. The present study was conducted to investigate whether the mitigating effect of melatonin is associated with its modulating influence on the mineral elements of cold‐stressed maize seedlings. The seedlings were treated with melatonin (1 mM) and cold stress (10/7°C) for 3 d separately and in combination. After 3 d, the seedlings were harvested to determine several physiological, biochemical, and molecular parameters. Melatonin application effectively mitigated the damages from cold stress, as demonstrated by higher relative water concentration, chlorophyll concentration and antioxidant enzyme activities (superoxide dismutase, guaiacol peroxidase, catalase, ascorbate peroxidase, and glutathione reductase), as well as lower superoxide, hydrogen peroxide, and malondialdehyde concentrations. Similarly, melatonin significantly ameliorated cold‐induced reductions in the concentrations of potassium, phosphorus, sulfur, magnesium, iron, copper, manganese, and zinc. Besides, it further increased calcium and boron concentrations compared to cold stress alone. Our results reveal that melatonin has an important modulating influence on the mineral element composition of plants and mitigates cold stress through up‐regulation of these elements and simultaneously enhanced antioxidant activity.     

Potential cell culture models for antioxidant research

The antioxidant activity of pure compounds, foods, and dietary supplements has been extensively studied with the development of many new antioxidant and antioxidant activity assays in recent years. However, these assays, such as total phenolics, total flavonoids, and total antioxidant activity in vitro, do not reflect the cellular physiological conditions and do not consider the bioavailability and metabolism issues. In addition, the mechanisms of action of antioxidants go beyond the antioxidant activity scavenging free radicals in disease prevention and health promotion. Animal models and human studies are expensive and not suitable for initial antioxidant screening of foods and dietary supplements. Therefore, there is a need for cell culture models to access the bioactivity of antioxidants. This paper is an overview of cell culture models for antioxidant research, as reported at the First International Congress on Antioxidant Methods, held in Orlando, FL, June 16-18, 2004, and outlines potential cell culture models for initial antioxidant screening and antioxidant research.     

Protective Roles of Calcium Channel Blocker Against Cadmium-Induced Physiological Stress in Freshwater Teleost Oncorhynchus mykiss

The roles of verapamil (VRP), a calcium channel blocker, on cadmium-induced physiological stress in freshwater teleost Oncorhynchus mykiss were investigated in this study. Forty-eight juvenile rainbow trout were divided randomly into four groups, i.e., control group, VRP group (100 μg/L VRP), Cd group (50 μg/L Cd²⁺), and VRP?+?Cd group (100 μg/L VRP?+?50 μg/L Cd²⁺). After 1-week exposure, oxidative stress indices (lipid peroxidation and carbonyl protein) and antioxidant parameters (superoxide dismutase, glutathione reductase, glutathione peroxidase, and reduced glutathione) were measured in gill and liver of all tested fish. Additionally, the behavioral changes were recorded during the experimental period. Compared with the control, cadmium-induced stress was apparent as reflected by a serious oxidative stress in gill and liver tissues, inhibited branchial antioxidant parameters, and induced hepatic antioxidant responses, as well as abnormal behaviors observed. In the VRP?+?Cd group, the antioxidant defense system of fish returned to the control level, and the fish behavioral abnormalism markedly decreased. The present results suggested that VRP could reduce the cadmium-induced physiological stress in rainbow trout and provided further evidence that Cd²⁺ uptake through Ca²⁺ transport pathways in freshwater teleost.     

Identification of hen egg yolk-derived phosvitin phosphopeptides and their effects on gene expression profiling against oxidative stress-induced Caco-2 cells

Oxidative stress is involved in the initiation and propagation of chronic intestinal pathologies. Bioactive peptides such as egg yolk-derived phosvitin phosphopeptides (PPP3) have been previously shown to reduce in vitro oxidative stress by up-regulating glutathione synthesis and antioxidant enzyme activities. Peptide and gene expression profile analysis of the PPP3 peptides can provide insight into structures involved in signal transduction mechanisms in the antioxidative stress response. The objectives of this research were to identify the PPP3 amino acid sequences before and after simulated gastrointestinal digestion and to assess the genes influenced by PPP3. Peptide sequences were analyzed using ESI Q-TOF-MS/MS, and the expression profile of 84 human oxidative stress and antioxidant defense genes were analyzed. Undigested PPP3 was composed of three main peptides: GTEPDAKTSSSSSSASSTATSSSSSSASSPNRKKPMDE (phosvitin-PV residues 4-41), NSKSSSSSSKSSSSSSRSRSSSKSSSSSSSSSSSSSSKSSSSR (PV residues 155-197), and EDDSSSSSSSSVLSKIWGRHEIYQ (PV residues 244-257) and their fragments. There was limited degradation of PPP3 after gastrointestinal digestion as deduced from the fragment sizes of digested PPP3, which ranged from 5 to 32 amino acids. These fragments were rich in contiguous serines and, in some cases, monoesterified with phosphate. Both undigested and digested PPP3 significantly reduced IL-8 secretion in H(2)O(2)-induced Caco-2 cells, indicating that antioxidative stress bioactivity is retained upon digestion. After PPP3 pretreatment, antioxidant genes associated with oxygen and reactive oxygen species (ROS) metabolism and cellular responses to chemical stimulus, oxidative stress, and ROS are up-regulated in the presence and absence of oxidative stress, thereby contributing to the prevention of intestinal oxidative stress and the promotion of gut health.     

山东省乡村旅游景点空间结构及影响因素研究

乡村旅游已成为农村实现产业融合的新型产业形态,为探求其开发和发展的空间结构,以山东省193个乡村旅游景点为研究样本,运用最近邻指数、多距离空间聚类分析和核密度分析等GIS空间分析和计量地理方法,对山东省乡村旅游景点的空间结构及影响因素进行定量研究,旨在为山东省乡村旅游的发展规划提出决策参考。结果显示:1)山东省乡村旅游景点的最近邻指数(R)为0.74,在空间分布上表现为典型的集聚型分布,主要分布于青岛、济南、临沂及枣庄4座城市周围。2)山东省乡村旅游景点热点区和冷点区空间差异明显,在省域尺度下表现出明显的"块状"分布特征。3)山东省乡村旅游景点受交通、区位、社会经济、资源禀赋、地形地貌等多种因素综合作用的影响。基于此,结合山东省乡村旅游发展现状提出两点建议:1)加强鲁东、鲁西、鲁北、鲁中4大片区合作,构建多个"核心—边缘"乡村旅游发展区。2)完善旅游交通网,实现景点之间的有机链接。     

Oxidant/antioxidant properties of Croatian native propolis

Native propolis was defined as propolis powder collected from the continental part of Croatia and prepared according to a patented process that preserves all the propolis natural nutritional and organoleptic qualities. Nine phenolic compounds (out of thirteen tested) in propolis sample were detected by high performance liquid chromatography (HPLC) analysis. Among them chrysin was the most abundant (2478.5 microg/g propolis). Contrary to moderate antioxidant activity of propolis examined in vitro (ferric reduction antioxidant power; FRAP-assay), propolis as a food supplement modulated antioxidant enzymes (AOE) and significantly decreased lipid peroxidation processes (LPO) in plasma, liver, lungs, and brain of mice. The effect was dose- and tissue-dependent. The lower dose (100 mg/kg bw) protected plasma from oxidation, whereas the higher dose (300 mg/kg bw) was pro-oxidative. Hyperoxia (long-term normobaric 100% oxygen) increased LPO in all three organs tested. The highest vulnerability to oxidative stress was observed in lungs where hyperoxia was not associated with augmentation of AOE. Propolis protected lungs from hyperoxia by increased catalase (CAT) activity. This is of special importance for lungs since lungs of adult animals are highly vulnerable to oxidative stress because of their inability to augment AOE activity. Because of its strong antioxidant and scavenging abilities, native propolis might be used as a strong plant-based antioxidant effective not only in physiological conditions but also in cases that require prolonged high concentration of oxygen.     

Responses of Components of Antioxidant System in Moongbean Genotypes to Cadmium Stress

Four genotypes (Pusa 9531, Pusa 9072, Pusa Vishal, PS‐16) of moongbean [Vigna radiata (L.) Wilczek] grown in earthen pots were treated with cadmium at 0, 25, 50, and 100 mg kg^?1 soil. Cadmium tolerance (CdT), the ability of a plant to maintain growth at high levels of cadmium (Cd), was calculated as the ratio of dry‐matter production in the untreated and the Cd‐treated soils. The moongbean genotypes showed a differential response to Cd concentrations; Pusa 9531 was identified as Cd tolerant, whereas PS 16 was Cd susceptible. To find out the physiological basis of these differences, we investigated the possible role of antioxidant (enzymatic and nonenzymatic) defense systems. Activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), and glutathione reductase (EC 1.6.4.2) and the amounts of ascorbate and glutathione were monitored in the Cd‐tolerant and Cd‐sensitive moongbean genotypes. The results revealed the presence of a strong antioxidant defense system in the Cd‐tolerant genotype (Pusa 9531) for providing adequate protection against oxidative stress caused by Cd.     

论梧州市观光旅游农业的开发

观光旅游农业是以农业为基础，将旅游业与农业叠加的复合型特殊产业，是可持续高效农业的一种理想开发途径，观光旅游农业的开发实施必然大大地促进农村产业结构的升级，推动农村经济建设和精神文明建设的进步。本文就梧州市观光旅游农业开发的重要意义、开发的有利条件、开发项目的选择与实施途径等方面展开了论述，以祈对梧州市观光旅游农业开发的决策和开发实施提供一定的指导作用。     

Nature-based tourism as a form of predation risk affects body condition and health state of Podarcis muralis lizards

Nature-based tourism has experienced a greater increase, and, even although it might have deleterious effects for many wildlife species, its consequences remains little explored. Many lizard species are endangered and tourism has been proposed as a potential factor responsible of the decline of several lizards’ populations, but no study has examined the effect of tourism on lizards’ behaviour, body condition and health state. Many lizards respond to people as if they were predators, by readily escaping to refuges. However, an increase in the frequency of these antipredatory strategies can lead to a loss of body condition, which may have important consequences for short and long term fitness. We analysed the effects of tourism on escape behaviour of common wall lizards, Podarcis muralis, as well as on their body condition and health state (ectoparasites, blood parasites, and cell mediated immune response). Results showed that lizards did not modify their escape behaviour in response to tourism. Lizards had similar approach and flight distances, and escape strategies regardless of the level of tourism pressure. However, lizards inhabiting areas with high tourism levels, where they presumably needed to perform antipredatory behaviours more often, showed higher intensity of infection by ticks and lower body condition at the end of the breeding period. Moreover, lizards with poorer body condition had lower cell mediated immune responses. Therefore, tourism seems to have deleterious effects on body condition and on host-parasite relationships in this lizard species. These effects should be taking into account when designing walking paths in protected areas. Our study reports evidence that regardless lizards showed similar escape behaviour in tourist than in natural areas, their body condition and health state should be also examined to accurately assess the actual effects of tourism on lizards’ populations.     

Juice and phenolic fractions of the berry Aristotelia chilensis inhibit LDL oxidation in vitro and protect human endothelial cells against oxidative stress

Oxidative modification of low-density lipoprotein (LDL) particles is a key event in the development of atherosclerosis. Oxidized LDL induces oxidative stress and modifies gene expression in endothelial cells. Berries constitute a rich dietary source of phenolic antioxidants. We found that the endemic Chilean berry Aristotelia chilensis (ach) has higher phenol content and scores better for total radical-trapping potential and total antioxidant reactivity in in vitro antioxidant capacity tests, when compared to different commercial berries. The juice of ach is also effective in inhibiting copper-induced LDL oxidation. In human endothelial cell cultures, the addition of ach juice significantly protects from hydrogen peroxide-induced intracellular oxidative stress and is dose-dependent. The aqueous, anthocyanin-rich fraction of ach juice accounts for most of ach's antioxidant properties. These results show that ach is a rich source of phenolics with high antioxidant capacity and suggest that it may have antiatherogenic properties.     

Effect of diets based on foods from conventional versus organic production on intake and excretion of flavonoids and markers of antioxidative defense in humans

Different food production methods may result in differences in the content of secondary metabolites such as polyphenolic compounds. The present study compared conventionally (CPD) and organically produced (OPD) diets in a human crossover intervention study (n = 16) with respect to the intake and excretion of five selected flavonoids and effect on markers of oxidative defense. The urinary excretion of quercetin and kaempferol was higher after 22 days of intake of the OPD when compared to the CPD (P < 0.05). The excretions of flavonoids in urine as a percentage of intake (0.6-4%) were similar after both interventions. Most markers of antioxidative defense did not differ between the diets, but intake of OPD resulted in an increased protein oxidation and a decreased total plasma antioxidant capacity compared to baseline (P < 0.05). Some varietal difference was seen in the study, and because selection of more resistant varieties is of central importance to organic farming, it cannot be excluded that the observed effects originate from these differences. The food production method affected the content of the major flavonoid, quercetin, in foods and also affected urinary flavonoids and markers of oxidation in humans.     

Amelioration of cadmium stress in gladiolus (Gladiolus grandiflora L.) by application of potassium and silicon

Gladiolus corms were grown in media contaminated with cadmium (Cd) (50 mg kg^?1) and supplemented with silicon (Si) and potassium (K). The role of Si and K for mitigation of Cd toxicity was evaluated. Cd-induced stress generated significantly increased level of oxidative stress markers including hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in gladiolus. The application of K and Si improved the production of protein and proline in the treated plants. Moreover, K and Si supplemented plants exhibited an improvement in the activity of antioxidant enzymes and a reduction in the level of MDA, H₂O₂ and Cd uptake under Cd stress. Application of K and Si also enhanced the uptake of mineral nutrients including calcium (Ca), magnesium (Mg), manganese (Mn), sulfur (S) and K. The plants supplemented with K and Si exhibited a higher amount of total phenolics and flavonoids. The combined effect of Si and K was more pronounced regarding beneficial effects on gladiolus plants compared to individual effect of these elements under Cd stress. The current research reveals that Si and K may improve gladiolus growth by decreasing the oxidative stress and Cd uptake and by increasing the activity of antioxidant defense enzymes, the quantity of secondary metabolites and plant nutrition.     

Relationship between apple peel and the whole fruit antioxidant content: year and cultivar variation

Antioxidants are usually considered with regard to plant defense mechanisms due to the oxidative stress or their importance for human health or both. In the present research, a comprehensive study was made to test the relationship between the antioxidant content in apple peel and the whole fruit in two growing seasons. Antioxidants were mainly localized in the apple peel, but cultivars exhibited very high biodiversity in the distribution pattern. High or very high correlation coefficients between apple peel glutathione reductase and catalase activity as well as ascorbate, glutathione, and anthocyanins concentrations and the whole fruit were discovered on the basis of both fresh and dry weight basis in two growing seasons: 2004 and 2005. In the case of ascorbate peroxidase activity and phenolics or flavonol contents, it was proven only in 2005. It seems that apple peel could be a good marker of health values as well as antioxidant potential of apple fruit. Additional arguments, as compared to the previous study, were incorporated to support the suggestion of glutathione reductase as worth considering as an environmental stress marker and/or signalling molecule.     

Cranberries and cranberry products: powerful in vitro, ex vivo, and in vivo sources of antioxidants

Cranberry products and especially cranberry juice (CJ) have been consumed for health reasons primarily due to their effect on urinary tract infections. We investigated the quantity of both free and total (after hydrolysis) phenolic antioxidants in cranberry products using the Folin assay. The order of amount of total polyphenols in cranberry foods on a fresh weight basis was as follows: dried > frozen > sauce > jellied sauce. On a serving size basis for all cranberry products, the order was as follows: frozen > 100% juice > dried > 27% juice > sauce > jellied sauce. High fructose corn syrup (HFCS) is a major source of sugar consumption in the U.S. and contains both glucose and fructose, potential mediators of oxidative stress. We investigated the effect of the consumption of HFCS and ascorbate with CJ antioxidants or without CJ (control) given to 10 normal individuals after an overnight fast. Plasma antioxidant capacity, glucose, triglycerides, and ascorbate were measured 6 times over 7 h after the consumption of a single 240 mL serving of the two different beverages. The control HFCS caused a slight decrease in plasma antioxidant capacity at all time points and thus an oxidative stress in spite of the presence of ascorbate. CJ produced an increase in plasma antioxidant capacity that was significantly greater than control HFCS at all time points. Postprandial triglycerides, due to fructose in the beverages, were mainly responsible for the oxidative stress and were significantly correlated with the oxidative stress as measured by the antioxidant capacity. Cranberries are an excellent source of high quality antioxidants and should be examined in human supplementation studies.