Educational value of different types of exhibits in an interactive science and technology center

This study analyzes the short-term consequences of visitors' use of different types of exhibits (i.e., "exemplars of phenomena" and "analogy based") together with the factors affecting visitors' understanding of and their evaluation of the use of such exhibits. One hundred and twenty five visitors (either alone or in groups) were observed during their interaction and interviewed immediately afterwards. Findings suggest that the type of exhibit constrains the nature of the understanding achieved. The use of analogical reasoning may lead to an intended causal explanation of an exhibit that is an exemplar of a phenomenon, but visitors often express misconceptions as a consequence of using this type of exhibit. Analogy-based exhibits are often not used as intended by the designer. This may be because visitors do not access the source domain intended; are unaware of the use of analogy per se (in particular, when the exhibit is of the subtype "only showing similarities between relationships"); only acquire fragmentary knowledge about the target; or fail to use analogical reasoning of which they were capable. Furthermore, exhibits related to everyday world situations are recognized to have an immediate educative value for visitors. Suggestions for enhancing the educative value of exhibits are proposed.

The nature of exhibits about acoustics in Science and Technology centres

This is a study of the opportunities currently provided by interactive science and technology centres for visitors' engagement in the field of acoustics. E-mails, requesting a description of exhibits on acoustics (sound and hearing) in use, were sent to members of staff of interactive science and technology centres around the world as well as to companies that design and sell exhibits. Eighty-seven descriptions of distinctive interactive exhibits were received and analysed. Results show that: there are few analogy-based exhibits concerning the more complex aspects of acoustics; narratives involving visitors' everyday lives, that might provide continuity between and beyond the situations presented by exhibits, are not generally provided; science is emphasised at the expense of technology; the risks, benefits and ethical implications of relevant technological artefacts are rarely mentioned; the majority of the exhibits are concerned with the fields of fundamental acoustics, hearing, and psychoacoustics. It is suggested that interactive science and technology centres need to rethink the design of exhibits about acoustics if their mission includes some appreciation of this important branch of science and technology.

Conjugated linoleic acid and human health-related outcomes

There has been increasing interest in health benefits of conjugated linoleic acid (CLA) based on findings with laboratory animals. Some human studies have also suggested health benefits of CLA, but because of the mixes used these could not be readily associated with a particular isomer of CLA. A recent study examined the separate effects of near-pure cis-9,trans-11 CLA (c9,t11 CLA) or trans-10,cis-12 CLA (t10,c12 CLA) on health-related outcomes in healthy young males. The CLA isomers were provided in capsules and at three doses (up to about 2.5 g/day) each for 8 weeks. Both c9,t11 and t10,c12 CLA were incorporated in a dose–response fashion into blood lipids and cells. At the doses and durations used, neither isomer of CLA affected bodyweight, body mass index or body composition, insulin sensitivity, immune function or markers of inflammation. However, at the doses and durations used, c9,t11 and t10,c12 CLA had opposing effects on blood lipid concentrations. Altered dairy cow-feeding practices were used to produce c9,t11 CLA-rich milk and, from this ultra heat-treated milk, cheese and butter were produced. The milk and the dairy products made from it had ninefold higher contents of c9,t11 CLA, higher contents of n-3 fatty acids and lower contents of total fat and of saturated fatty acids. They also contained much higher contents of trans-vaccenic acid (tVA). The modified dairy products were used in a 6-week controlled dietary intervention study in healthy middle-aged males. c9,t11 CLA and tVA were incorporated from dairy products into blood lipids and cells. Consumption of the CLA-rich (and tVA-rich) dairy products did not affect bodyweight or body mass index, insulin sensitivity or inflammatory markers. However, there were some detrimental effects on blood lipids. These effects may be due to tVA rather than to c9,t11 CLA, as they are consistent with the effects of trans fatty acids and not consistent with the effects of c9,t11 CLA identified in the earlier study with c9,t11 CLA in capsules.

Glucosinolates in brassica vegetables: the influence of the food supply chain on intake, bioavailability and human health

Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

Conjugated linoleic acid and human health: a critical evaluation of the evidence

Purpose of review: This review critically evaluates studies investigating the effects of conjugated linoleic acid on human health, including effects on body composition, blood lipids, liver metabolism, insulin sensitivity and immune function. It focuses mainly on human intervention studies, but includes some reference to animal and cellular studies which provide insight into potential molecular mechanisms of action of conjugated linoleic acid. Recent findings: Human studies continue to report inconsistent effects of conjugated linoleic acid on human health. Some of these reports are based on overinterpretation of marginal effects of supplementation. Recent data suggest that the effects of the substance may be isomer dependent and that cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acids have opposing effects on blood lipids and on metabolism in adipocytes and hepatic cells. Summary: Claims that conjugated linoleic acid is beneficial for health remain as yet unconvincing. Human studies investigating the effects of conjugated linoleic acid supplements have tended to use mixtures of isomers and have been inconsistent. More recent studies have attempted to use relatively pure preparations of single isomers and these studies suggest that the effects of conjugated linoleic acid may be isomer-specific. These recent data suggest a relative detrimental effect of trans-10, cis-12 conjugated linoleic acid on blood lipids. There appears to be little effect of conjugated linoleic acid on immune function and the effects on insulin sensitivity remain unclear.

Antioxidant and cellular activities of anthocyanins and their corresponding vitisins A - studies in platelets, monocytes, and human endothelial cells

During red wine aging, there is a loss of anthocyanins and the formation of various other pigments, so-called vitisins A, which are formed through the chemical interaction of the original anthocyanins with pyruvic acid. The objective of this study was to investigate the antioxidant activities of the most abundant anthocyanins present in red wine (glycosides of delphinidin, petunidin, and malvidin) and their corresponding vitisins A. Anthocyanins exhibited a higher iron reducing as well as 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonate) and peroxyl radical scavenging activity than their corresponding vitisins A. Delphinidin showed the highest antioxidant effect of the tested compounds in all of the assays used. Furthermore, we studied the effect of anthocyanins and vitisins A on platelet aggregation and monocyte and endothelial function. Anthocyanins and vitisins did not affect nitric oxide production and tumor necrosis factor-alpha (TNF-alpha) secretion in lipopolysaccharide plus interferon-gamma-activated macrophages. Furthermore, anthocyanins and vitisins did not change collagen-induced platelet aggregation in vitro. However, anthocyanins and to a lesser extent vitisins exhibited protective effects against TNF-alpha-induced monocyte chemoattractant protein production in primary human endothelial cells.

Omega-3 polyunsaturated fatty acids and human health outcomes

Current intakes of very long chain omega-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DNA) are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids too. Very long chain w-3 fatty acids are readily incorporated from capsules into transport, functional, and storage pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, eicosanoid generation, cell signaling and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology, and the way cells and tissues respond to external signals. In most cases, the effects seen are compatible with improvements in disease biomarker profiles or in health-related outcomes. As a result, very long chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long chain omega-3 fatty acids protect against cardiovascular morbidity and mortality, and might be beneficial in rheumatoid arthritis, inflammatory bowel diseases, childhood learning, and behavior, and adult psychiatric and neurodegenerative illnesses. DHA has an important structural role in the eye and brain, and its supply early in life is known to be of vital importance. On the basis of the recognized health improvements brought about by long chain omega-3 fatty acids, recommendations have been made to increase their intake. (C) 2009 International Union of Biochemistry and Molecular Biology, Inc. Volume 35, Number 3, May/June 2009, Pages 266-272. E-mail: pcc@soton.ac.uk