Pentti Hietala

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This paper investigates the laxative effect and acute toxicity of certain fractions of senna extracts in mice. The same tests were also carried out with several pure anthraquinone derivatives common in senna pods. The results show that the laxative and toxic components of senna pods and senna extracts can be separated. The most potent laxative components,(More)
The amino acid derivative 2-hydroxyisocaproic acid (HICA) is a nutritional additive used to increase muscle mass. Low levels can be detected in human plasma as a result of leucine metabolism. It has broad antibacterial activity but its efficacy against pathogenic fungi is not known. The aim was to test the efficacy of HICA against Candida and Aspergillus(More)
Pure sennoside B was administered to rats. On appearance of the first wet faeces, sennoside B and its metabolites were determined in different parts of the alimentary tract, in faeces and in the urine. The total recovery of unchanged sennoside B and its metabolites was determined by alkali fusion followed by colorimetry and high-pressure liquid(More)
One recent approach in developing computer-based learning environments advocates the idea of creating a social context inside the computer. It is claimed that when the learner is engaged into a meaningful dialogue with the software actors his/her learning will benefit. In this paper we concentrate on the collaboration with artificial social actors as peer(More)
Whiteboards have proven valuable for informal note-taking and sketching. Different electronic and also interactive whiteboards are becoming available for children and their teachers at all school levels. We describe the first experiences of children at a day care centre when using an electronic whiteboard for creative letter recognition in small groups.(More)
This paper focuses on developing, testing, and examining the Proagents multimodal learning environment to support blind children’s explorative learning in the area of astronomy. We utilize haptic, auditive, and visual interaction. Haptic and auditory feedbacks make the system accessible to blind children. The system is used as an exploration tool for(More)
In Virtual Learning Environments efficient navigation is a major issue, especially when it is used as a component in the learning process. This paper addresses the challenges in creating meaningful navigation routes from language learning perspective. The work is grounded on findings from a specific case on German language learning, wherein two remotely(More)