Showing papers by "University of Constantine the Philosopher published in 2005"

Changes of femoral bone tissue microstructure in transgenic rabbits.

Abstract: Bone tissue microstructure of femur was investigated in transgenic New Zealand White rabbits with human factor VIII gene. Altogether 42 bones (24 from transgenic rabbits and 18 from non-transgenic ones) were analysed. Specimens were prepared using standard histological equipment, producing thin sec- tions of approximately 80-100 µm. For histomorpho- metrical analysis areas, perimeters, minimum and maximum diameters of osteons' vascular canals and of osteons were measured. We found out that the basic structural pattern of femoral bone tissue was primary vascular longitudinal in both groups of rabbits. How- ever, a new type of the bone tissue - fibrolamellar - was identified only in the transgenic rabbits. The measured variables of the osteons' vascular canals were higher in transgenic individuals in comparison with the non- transgenic ones (except for maximal diameter) and the differences were statistically significant (P < 0.05; P < 0.01). We suppose that the observed differences could be associated with transgenesis. In an effort to explain these differences we compared the cytogenetic profile of bone marrow cells between transgenic and non- transgenic rabbits. A significantly higher rate of aneu- ploidy was observed in c-metaphase spreads of transgenic individuals as compared to non-transgenic ones (P < 0.001). Despite the fact that no hFVIII mRNA expression was found in the femur of transgenic rab- bits, we discussed an association of transgene integra- tion into the genome and microstructural changes in the bone. In any case, the results indicate that transge- nesis can also produce changes in other tissues than in the target ones. The microscopic structure of rabbit long bones con- sists in general of primary vascular longitudinal bone tissue. The tissue is created by vascular canals of osteons which run in a direction essentially parallel to the long axis of the bone (Enlow and Brown, 1956). In

Using spreadsheet calculations to demonstrate concepts of programming

Abstract: 'Experiment', 'discovery' and 'self-teaching' are basic bricks of active learning. Despite the fact that learners are investigating notions and relationships known long before, their own discovery of something new and unknown for them results in their fascination with an irreplaceable educational value. Spreadsheets are one of the environments that can successfully be used for building stages in similar experimentation. Today, computer literacy courses (i.e. file management, word processing and spreadsheet calculations) frequently precede programming courses. They give us an opportunity to introduce programming concepts using the students' computer-related erudition – by solving problems that they can solve by other means. Spreadsheets have a special value in this sense. Their calculations can be seen as 'program outputs of hidden programs'. By drawing the curtain away from the hidden processes, one can illustrate concepts and properties that are typical for all programs. Activities described in our paper show how spreadsheet-based calculations can lead students to a deeper comprehension of algorithms, their design, development and execution.

Comparison of quantitative microscopic and submicroscopic analyses of the liver in cows bred in various polluted regions

Abstract: The influence of polluted environment on microscopic and submicroscopic structure of the liver in cows was studied. Experimental animals came from two areas of East Slovakia: Strednogemerska and Kosicka. Samples of the liver were taken from adult (range 6-8 years) cows, then were prepared for light and electron microscopy by standard methods. We analysed their morphological structures and gave them morphometric values. All the results were processed statistically. Some differences between results from experimental animals in morphological and stereological analyses were found. A significant increase in a relative volume of capillaries in quantitative microscopic analysis was noted. On the other hand, a significant decrease in the relative volume of mitochondria and significant increase in the relative volume of rough endoplasmic reticulum were observed.