Inflammatory bowel disease is characterized by oxidative stress, inflammation and tissue damage. Vitamin A is an antioxidant, a regulator of epithelial proliferation and differentiation and vital for optimal immune function. To investigate the effect of vitamin A on the course of colitis, it was induced by administration of trinitrobenzene sulfonic acid (TNBS) into the colons of rats fed for 7 wk vitamin A-deficient (VAD), sufficient (VAS) or supplemented (VASUP) diet, or VAS pair-fed (PF) to the VAD rats. Inflammation and fibrosis were examined by hematoxin and eosin, and Sirius red staining. Activation of nuclear factor-kappaB (NF-kappaB) and oxidative stress were determined by electrophoretic mobility shift and plasma malondialdehyde (MDA) and RBC Cu/Zn-superoxide dismutase activity, respectively. Vitamin A deficiency in the noncolitic rats impaired food consumption and weight gain (P < 0.05) and increased plasma MDA, (P = 0.01) activity of NF-kappaB (P < 0.05) and deposition of collagen in the colon. Our data suggest that vitamin A deficiency induces colonic inflammation. Colitis is amplified by deficiency and ameliorated by supplementation of the vitamin. These findings have implications for the management of inflammatory bowel disease.

The aim of this study was to examine the influence of lycopene and beta-carotene on the inflammatory status in a rat model of induced-colitis. Using the 2,4,6-trinitrobenzenesulfonic acid (TNBS) model, colitis was induced in thirty-two male Wistar rats divided into four groups. Each group received a different diet regime in parallel with the induction of colitis and was sacrificed after seven days. The groups were divided as follows: Group A: without colitis and fed a normal chow diet; Group B: induced with colitis and fed a diet supplemented with lycopene (300 micrograms/rat/day); Group C: induced with colitis and fed a diet supplemented with beta-carotene (300 micrograms/rat/day); Group D: induced with colitis and fed a normal chow diet. Colonic inflammation following TNBS induction was characterized by hemorrhagic necrosis and fibrosis of the mucosa, increased colonic wall thickness, infiltration of inflammatory cells, and increased myeloperoxidase (MPO) activity. Supplementation of lycopene in the diet had a beneficial effect on the various macroscopic parameters examined including: colonic thickness, colon weight, and total area of inflammation. Furthermore, the level of myeloperoxidase (MPO) was significantly lower in the lycopene-treated group compared to the control group. In terms of microscopic changes, a more attenuated inflammatory reaction was observed in the group fed a diet supplemented with lycopene. No significant effect was noted in the beta-carotene-supplemented group. Therefore, we propose that the dietary supplementation of lycopene may be an effective approach for reducing the level of oxidative stress and improving the inflammatory status of colitis.

Our results suggest that vitamin-A deficiency modifies the maturation and differentiation processes of the small intestinal mucosa at the transcriptional and post-transcriptional levels respectively. This in turn may be one explanation for the alteration or elimination of nutrient digestion and absorption during VAD.

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The present study focuses on the Internet activity of young children in order to examine how these children utilized the Internet and their potential in the uses of the Internet. The study sample consisted of 20 children, from both compulsory and pre-compulsory kindergarten. Two Internet learning environments were examined: (1) the 'universal' environment of the Web, where a search engine was used for navigation; and (2) the 'modified' Web environment, which was created in accordance with the abilities and level of young children. It was shown that young children who operated in a 'modified' Internet environment manifested better control of the uses of Internet interfaces and were better oriented in the Internet environment when compared with their activity in the 'universal' Internet environment. Another finding was that not all of the Internet uses constitute a meaningful learning environment for young children. In order for the environment to be advantageous for children, Internet uses must be structured in accordance with the children's levels of development and needs, with the emphasis on the use of the Internet as a source of information in parallel with concrete activity and teacher/adult mediation in the children's Internet activity.