The mechanisms for regulating absorption of Fe bis-glycine chelate and Fe-ascorbate in caco-2 cells are similar

Inorganic iron (Fe) absorption from the diet is controlled mainly in the intestinal tract where apical Fe uptake is inversely related to the Fe content in the enterocyte. Iron bis-glycine chelate is an iron compound that may be absorbed by a mechanism different from the regulated nonheme Fe pathway. Because Fe bis-glycine chelate is used increasingly as an Fe fortificant in foods, the critical question is whether this compound is a safe Fe supplement. We compared apical Fe uptake and transepithelial transport offered either as (59)Fe bis-glycine chelate or a (59)Fe-ascorbate (Fe-AA) complex in Caco-2 cells, as a model of human intestinal epithelia, grown in different Fe concentrations in the media (0.5, 5 and 20 micro mol/L Fe). Apical Fe uptake from (59)Fe-AA and (59)Fe bis-glycine chelate did not differ nor did transepithelial transport rates. The rate of (59)Fe uptake decreased with increasing intracellular Fe concentration (P < 0.001), an indication of a common absorption regulatory mechanism. We also evaluated the effect of an excess of Fe (100 micro mol/L) provided as Fe bis-glycine chelate or Fe-AA on the incorporation of 1 micro mol/L (55)Fe-AA into Fe-replete Caco-2 cells. The inhibition of Fe bis-glycine chelate on the absorption of the extrinsic tag of (55)Fe-AA (87.5%) did not differ from that of Fe added as Fe-AA (86.8%). These results suggest that Fe derived from Fe bis-glycine chelate and Fe-AA have similar regulatory absorption mechanisms.     

Soy protein peptic hydrolysate with bound phospholipids decreases micellar solubility and cholesterol absorption in rats and caco-2 cells.

This experiment was designed to evaluate the effects of casein, soy protein, soy protein with bound phospholipids (SP), soy protein peptic hydrolysate (SPH) or soy protein peptic hydrolysate with bound phospholipids (SPHP) on the micellar solubility of cholesterol and the taurocholate binding capacity in vitro. We also evaluated the effects of various proteins on cholesterol metabolism in rats and Caco-2 cells. SPHP had a significantly greater bile acid-binding capacity than that of SPH in vitro. Micellar cholesterol solubility in vitro was significantly lower in the presence of SPHP compared to casein tryptic hydrolysate (CTH). The cholesterol micelles containing SPHP and SPH significantly suppressed cholesterol uptake by Caco-2 cells compared to the cholesterol micelles containing CTH. Consistent with these findings in the in vivo cholesterol absorption study using radioisotopes, fecal excretion of total steroids was significantly greater in rats fed the SPHP diet compared with those fed the casein, soy protein, SP and SPH diets. Serum total cholesterol was significantly lower in rats fed SPHP than in those fed casein. The concentrations of total lipids and cholesterol in liver were significantly lower in the SPHP-fed group compared with all other groups. These results suggest that the suppression of cholesterol absorption by direct interaction between cholesterol-mixed micelles and SPHP in the jejunal epithelia is part of the mechanism underlying the hypocholesterolemic action of SPHP. SPHP may also inhibit the reabsorption of bile acids in the ileum, thus lowering the serum cholesterol level.     

Resveratrol enhances the differentiation induced by butyrate in caco-2 colon cancer cells

Butyrate, a short-chain fatty acid produced in the colon by microbial fermentation of fiber, inhibits growth of colonic carcinoma cells while inducing differentiation. Resveratrol, a plant polyphenol found in red wine and peanuts, has been shown to exert chemopreventive properties on colon cancer cells. The aim of this study was to determine whether resveratrol modulates the effects of butyrate on Caco-2, a colonic adenocarcinoma cell line. The growth inhibitory effect of resveratrol (50 micromol/L) was more powerful than that of butyrate (2 mmol/L). Butyrate did not intensify the inhibition of proliferation exerted by resveratrol. Although the polyphenol enhanced the differentiation-inducing effect of butyrate, it did not elevate alkaline phosphatase activity or E-cadherin protein expression, markers of epithelial differentiation, when applied alone. Butyrate-induced transforming growth factor-beta1 secretion was inhibited by resveratrol. Treatment with the combination of resveratrol and butyrate attenuated levels of p27(Kip1), whereas resveratrol enhanced butyrate's effect on the induction of p21(Waf1/Cip1) expression. These data demonstrate a possible combined chemopreventive effect of two substances naturally occurring in the colonic lumen after ingestion of fibers and resveratrol-containing food.     

The critical appraisal of focus group research articles

Objectives: To determine whether the three mailings routinely used by researchers for epidemiological surveys are useful and appropriate, by comparing social characteristics and selected disease histories to find out if there are differences between individuals responding at different times.

Methods: Social characteristics and selected disease histories of 11,797 British women still under general practitioner observation in the Royal College of General Practitioners' Oral Contraception Study were compared. The women aged 40-78 at December 1992 were sent health survey questionnaires via their general practitioners between November 1994 and July 1995.

Results: Significant differences in the characteristics of first, second and third mailing respondents and non-respondents were found for smoking habits, social class, parity, area of residence, further contact, bronchitis, hysterectomy and mental illness. First mailing respondents were more likely to be from a non-manual social class, have a parity of less than three, live in England, and be happy to be contacted again, but were less likely to have had bronchitis or mental illness and were less likely to have been smokers at the time of recruitment than second mailing respondents. A comparison of second and third mailing respondents on the above factors showed no significant differences between the two groups.

Conclusions: The inclusion of third mailing respondents did not significantly change the social or health characteristic profile of the cohort and suggests that the effort and resources expended in carrying out a third mailing may not be justified.     

The use of knee height to estimate maximum stature in elderly Chinese

Loss of height occurs in the elderly. Not only is this height valuable to assess, but it creates difficulty for comparisons using equations based on estimates of stature in adult populations which often overlook the loss of height with age. Alternatives, such as the use of arm-span or hip length as surrogates for maximum stature (MS) during adulthood, have been proposed. In a study of 247 (130 men and 117 women) adult ethnic Chinese living in Melbourne, Australia, we tested the hypothesis that knee height is independent of age and attempted to devise an equation for the estimation of maximum stature (MS) in the this elderly group (aged 65 yrs) of this population. Anthropometric indices, including body weight, stature, arm-span, and knee height were twice measured using standard methods described by Lohman et al., and averaged for use in the analysis. In both men and women, the younger adults were taller and had a greater arm-span than their elderly counterparts: however, there was no difference in knee height or body weight between the two groups. Knee height was not associated with age, while stature and arm-span correlated negatively with age. These findings suggest that knee height provides for a valid estimate of MS during early adulthood than arm-span. Knee height is independent of age and does not appear to decreased over time, in spite of an expected cohort effect in this population. Arm-span, however, appears to change with a cohort as well as with age. Thus, there is a place in a life-time nutritional assessment of the aged to measure both arm-span as an index of cohort status and knee height for an individual's maximum achieved stature.     

EHEC O157∶ H7粘附Caco-2细胞缺陷突变株的构建

目的:构建对肠上皮细胞粘附缺陷的肠出血性大肠埃希菌O157∶ H7(EHEC O157)突变株,为体内、体外研究其粘附机制提供可用工具.方法:将pSC101和mini-Tn5Km2分别通过转化和结合导入O157Sakai菌株中,筛选粘附力缺陷的转化子感染Caco-2细胞株,观察Caco-2单层细胞中的微菌落数量和mini-Tn5Km2插入位点.结果:经诱变,共分离到3组粘附缺陷突变株,1组完全丧失了粘附力,2组粘附力减弱,3组的粘附力更弱.1组和3组拥有LEE岛上多基因的转座子插入,而2组mini-Tn5Km2的插入位点在LEE岛之外.结论:O157Sakai的肠道粘附能力可能与LEE岛的III型分泌系统有关.     

The use of participatory appraisal by veterinarians in Africa

The term 'participatory appraisal' refers to a range of methods for data collection, learning and facilitation, which enable local people to play an active role in defining, analysing and solving their problems. A questionnaire survey was used to obtain information on the use of participatory appraisal (PA) from veterinarians working in Africa. A low overall response rate of 28.6% was achieved. Within Africa, response rates varied from 15.6% from government veterinarians to 47.6% from veterinarians working with non-governmental organisations. Information is presented on preferred methods, specific uses, levels of training and perceived advantages and disadvantages of PA. While PA was considered by many informants to be a valuable approach to working with communities to analyse and solve local animal health problems, respondents also identified constraints to the wider use of PA. These constraints included lack of financial resources, low availability of relevant training courses and materials, lack of time to attend training courses, and negative attitudes among colleagues. The author concludes that greater institutional awareness of the role of PA in the development of Veterinary Services is required. Such awareness might be achieved by wider dissemination of experiences related to the use of PA and the development of veterinary-orientated training courses for centrally-based personnel and workers in the field. The latter should include attention to appropriate attitudes and behaviour for veterinary professionals who are attempting to develop services according to the priorities and capacity of the community.     

Nucleotide and nucleoside supplementation may morphologically promote the differentiation of human caco-2 cells

The effects of nucleotide and nucleoside supplementation on the formation of tight junctions and the expression of microvilli, as indexes of morphological differentiation were studied by using a human colon adenocarcinoma cell line (Caco-2 cells). The formation of tight junctions and the expression of microvilli were evaluated by measuring the transepithelial electrical resistance (TEER) and observing the cell surface under electron microscopic analysis, respectively. To clarify the nutritional significance of human milk nucleotides. we used a nucleotide mixture (and a corresponding nucleoside mixture) with a composition similar to that found in human milk. Nucleotides had no effect on TEER, but nucleosides markedly promoted the increase of TEER. When alkaline phosphatase activity in the brush border membrane was enhanced by the addition of triiodothyronine (TIT), nucleotides also promoted the increase of TEER. Cytidine and CMP predominant in the mixture influenced the increase of TEER materially. Furthermore, an electron microphotograph of the cell surface showed that nucleosides contributed to the expression of microvilli. Thus the results presented in this study suggest that nucleotide and nucleoside supplementation may enhance the morphological differentiation of Caco-2 cells.     

EHEC O157:H7肠粘附力增强突变株的构建

[目的]构建对肠上皮细胞粘附力增强的肠出血性大肠埃希菌O157H7(EHEC O157)突变株,为体内、体外研究其粘附及其粘附机制提供可行的手段.[方法]分别将pSC101和mini-Tn5Km2通过电穿孔转化和结合导入O157H7-Sakai菌株中,筛选粘附力增强的转化子感染Caco-2细胞株和实验小鼠,观察Caco-2单层细胞中的微菌落数量和小鼠粪便中突变株脱落的时程.[结果]经诱变,共分离筛选出8株突变株,其形成微菌落的数量大于野毒株至少3倍以上;8个突变株中有6株转座子的插入位置为E.coli K-12同源区的yhiE基因处,其突变株在小鼠粪便中的脱落时程明显高于野毒株,P<0.01.[结论]O157Sakai中的yhiE基因可能具有调节O157粘附肠道上皮细胞能力的作用,尽管其调节机制尚有待于进一步阐明,但本文结果显示其可能具有负调节的作用.另外,本文分离到的O157Sakai粘附增强突变株将为进一步在体内和体外研究EHEC对宿主肠上皮粘附的调节机制提供一个有效的工具.     

The use of sticky ovitraps to estimate dispersal of Aedes aegypti in northeastern Mexico

A newly designed sticky ovitrap was used to determine the dispersal flight of the dengue vector Aedes aegypti in northeastern Mexico. Unfed marked females were released in the field where 100 sticky ovitraps had been positioned within a circular area 300 m in diameter. Success of this method was represented by a 7.7% (31 of 401) recapture rate during a 19-day sampling period. The maximum dispersal distance was 120 m with a mean of 30.5 m +/- 4.5 SD. Drastic hot and dry climatic conditions at the study site may have restricted mosquito dispersal. As expected, mostly gravid female mosquitoes were captured in the ovitraps. The method of sticky ovitraps proved to be useful and inexpensive for Ae. aegypti dispersal studies in Latin American countries. In addition to the marked mosquito populations, unmarked Ae. aegypti, Culex sp., roaches, and even small vertebrates such as lizards and sparrows were found glued to the sticky ovitraps. Based on these studies, the use of sticky ovitraps is recommended for Ae. aegypti dispersal studies, specially for dengue control programs in developing countries.     

On the concept of eugenics: preliminaries to a critical appraisal

This paper's main issue is linked to what can be foreseen as the increasing capability of medical genetics to modify the genetic composition of the human species through direct interventions in the human genome for medical and non-medical purposes, i.e., the "risk" of a resurgence of eugenics. In current discussions on the topic (briefly presented in the first section), the "phantom of eugenics" is raised several times, but there is a great deal of confusion on what counts as eugenics, partly because of broad conceptual disagreement over the notion itself. Furthermore, according to some scholars there is no hope of overcoming this unsatisfactory conceptual uncertainty. Partly challenging this opinion, the second and third sections of this paper attempt to identify some basic features which could be seen as intrinsically linked to the notion of eugenics, with the aim of reducing the range of conceptual disagreement as a preliminary step in bringing into focus what exactly is wrong with practicing eugenics. The subsequent sections deal with the substantive issue of whether or not to practice eugenics from the point of view of the interest of future generations in the human species' genetic composition. The main moral arguments for and against eugenics are examined from the point of view of our obligations towards future generations, and the conclusion is in favor of a cautious "open-door" position.