The antioxidants are essential molecules in human system but are not miracle molecules. They are neither performance enhancers
nor can prevent or cure diseases when taken in excess. Their supplemental value is debateable. In fact, many high quality
clinical trials on antioxidant supplement have shown no effect or adverse outcomes ranging from morbidity to all cause mortality.
Several Chochrane Meta-analysis and Markov Model techniques, which are presently best available statistical models to derive
conclusive answers for comparing large number of trials, support these claims. Nevertheless none of these statistical techniques
are flawless. Hence, more efforts are needed to develop perfect statistical model to analyze the pooled data and further double
blind, placebo controlled interventional clinical trials, which are gold standard, should be implicitly conducted to get explicit
answers. Superoxide dismutase (SOD), glutathione peroxidase and catalase are termed as primary antioxidants as these scavenge
superoxide anion and hydrogen peroxide. All these three enzymes are inducible enzymes, thereby inherently meaning that body
increases or decreases their activity as per requirement. Hence there is no need to attempt to manipulate their activity nor
have such efforts been clinically useful. SOD administration has been tried in some conditions especially in cancer and myocardial
infarction but has largely failed, probably because SOD is a large molecule and can not cross cell membrane. The dietary antioxidants,
including nutrient antioxidants are chain breaking antioxidants and in tandem with enzyme antioxidants temper the reactive
oxygen species (ROS) and reactive nitrogen species (RNS) within physiological limits. Since body is able to regulate its own
requirements of enzyme antioxidants, the diet must provide adequate quantity of non-enzymic antioxidants to meet the normal
requirements and provide protection in exigent condition. So far, there is no evidence that human tissues ever experience
the torrent of reactive species and that in chronic conditions with mildly enhanced generation of reactive species, the body
can meet them squarely if antioxidants defense system in tissues is biochemically optimized. We are not yet certain about
optimal levels of antioxidants in tissues. Two ways have been used to assess them: first by dietary intake and second by measuring
plasma levels. Lately determination of plasma/serum level of antioxidants is considered better index for diagnostic and prognostic
purposes. The recommended levels for vitamin A, E and C and beta carotene are 2.2–2.8 μmol/l; 27.5–30 μmol/l; 40–50 μmol/l
and 0.4–0.5 μmol/l, respectively. The requirement and recommended blood levels of other dietary antioxidants are not established.
The resolved issues are (1) essential to scavenge excess of radical species (2) participants in redox homeostasis (3) selective
antioxidants activity against radical species (4) there is no universal antioxidant and 5) therapeutic value in case of deficiency.
The overarching issues are (1) therapeutic value as adjuvant therapy in management of diseases (2) supplemental value in developing
population (3) selective interactivity of antioxidant in different tissues and on different substrates (4) quantitative contribution
in redox balance (5) mechanisms of adverse action on excess supplementation (6) advantages and disadvantages of prooxidant
behavior of antioxidants (7) behavior in cohorts with polymorphic differences (8) interaction and intervention in radiotherapy,
diabetes and diabetic complications and cardiovascular diseases (9) preventive behavior in neurological disorders (10) benefits
of non-nutrient dietary antioxidants (11) markers to assess optimized antioxidants status (12) assessment of benefits of supplementation
in alcoholics and heavy smokers. The unresolved and intriguing issues are (1) many compounds such as vitamin A and many others
possessing both antioxidant and non-antioxidant properties contribute to both the activities in vivo or exclusively only to
non-antioxidant activity and (2) since human tissues do not experience the surge of FR, whether there is any need to develop
stronger synthetic antioxidants. Theoretically such antioxidants may do more harm than good. 相似文献
This paper reports on a project aimed at identifying and exploring the development and implementation processes of teaching practices with interactive whiteboards (IWBs) in two Swedish K-6 schools. The purpose of the project was to generate results and insights of value when preparing student teachers for professional use of IWBs and to give school leaders guidelines when implementing IWBs. A range of methods were used to collect rich and varied empirical materials in this exploratory project. Judging from our data, it was obvious that the implementation process of IWBs, just like other information and communication technology initiatives, is very technology-oriented, but also dependent on attitudes. Over the course of time in the project, different strategies emerged among the teachers regarding whether and how they used the IWBs in their lectures. It also became increasingly clear during the study that there is a distinction between technical interactivity and pedagogical interactivity. Our results further suggest that training is needed when introducing these boards for future users. This training should include both technical instructions and pedagogical discussions. 相似文献
Previously we showed how we measured pedagogy and revealed its association with learning outcomes of sixth‐form college mathematics students. In this project we followed a similar approach to the study of university transition. We particularly sought to identify the students’ perceptions of the transitional experience, and measure the association with learning outcomes. We drew on longitudinal surveys of students entering different programmes in five universities. Following them into their first year or so, allowed us to track their ‘disposition to complete the course’ and their ‘disposition to study more mathematics’, inter alia. We developed and validated two ‘fit‐for‐purpose’ measures of students’ perception of their transition, one we call ‘perception of the transitional gap/jump’ and one we call ‘degree of positive feeling about the transition’. We report some statistically and educationally significant associations between these and the students’ developing dispositions, and discuss the prospects for this approach to studying transition. 相似文献
This paper reports on the second phase of a multi-country study examining cross cultural perspectives of gender and management in Higher Education Institutions (HEIs). It examines the broader labour market context and legislative frameworks for higher education in each country and then analyses the literature on women in university management. The paper presents the findings of research with male and female senior managers about their perceptions of women as HEI managers within changing organisational and management structures. It concludes that although HEI’s are now largely aware of barriers to women getting into and on in senior management, they have not addressed the organisational structures and cultures that perpetuate this inequity.
Almost all 3‐ and 4‐year‐olds in Scotland now experience some form of pre‐school provision prior to school entry. Given such high rates of participation, the impact of pre‐school experiences on children's readiness for primary school has become an important issue for those involved in the early stages of compulsory schooling. Teachers in early years classes need to be aware of the experiences and achievements of individual children in their pre‐school setting to enable each child to transfer into mainstream education with the least amount of disruption to their learning. This study was carried out in one small Scottish local authority and explored the perceptions of early years teachers, from a diverse range of primary schools, of what information is important for them as children start school. This article presents the perspectives of Primary 1 teachers on children's readiness for schooling. It reports the factors, which these teachers identified as having an impact on successful transition from the pre‐school setting into the primary school. 相似文献
Plant Growth Promoting Rhizobacteria (PGPR) are a group of bacteria that enhances plant growth and yield via various plant growth promoting substances as well as biofertilizers. Given the negative environmental impact of artificial fertilizers and their increasing costs, the use of beneficial soil microorganisms such as PGPR for sustainable and safe agriculture has increased globally during the last couple of decades. PGPR as biofertilizers are well recognized as efficient soil microbes for sustainable agriculture and hold great promise in the improvement of agriculture yields. 相似文献
The rigours of the past few years have demonstrated the importance of good health literacy levels with the imperative of being able to obtain and interpret information to maintain and improve one's health never more apparent. With this in mind, this issue is focused on consumer health information, the gender and population group differences that exist in information seeking behaviour, the challenges of understanding medical explanations and terminology, and existing criteria to assess and ultimately produce better consumer health information. 相似文献
This article presents an empirical study focused on a qualitative analysis of the UNIMARC format. An analysis of the structural quality of the data provided by the format is evaluated to determine its current suitability for meeting the requirements and trends in data architecture for the information network and the Semantic Web. Driven by a set of quality characteristics that identify weaknesses in the data schema that cannot be bridged by simply converting data to MARC XML or RDF/XML, we conclude that the UNIMARC format is not compliant with the current metadata schema desiderata and must be replaced. 相似文献
This study explored the correspondence and differences between school staff perceptions of preschool children's social skills and behavior problems. One hundred preschoolers were assessed by 14 pairs of teachers and classroom aides with the Preschool and Kindergarten Behavior Scales – 2nd Edition (PKBS‐2 Portuguese version). Indexes of agreement and disagreement were calculated. Risk levels and item analyses of PKBS‐2 scores according to both informants' ratings were compared. A higher level of agreement was obtained for social skills scores than for behavior problems (mean correlation of .62). No statistically significant differences between informants were obtained for the risk levels, and item analyses revealed a similar pattern of behaviors that were most and least rated by both informants. Results indicate that the classroom aides' perspective on preschool assessment represents a reliable input, which justifies that they network with teachers in addressing preschoolers' social‐emotional and behavioral challenges. 相似文献