Bachelor's Defense

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This presentation was for the defense of my Bachelor's degree thesis at the University of Copenhagen.

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  • I will be presenting and defending my bachelor’s thesis, with the title .. And the project were conducted at the department of physical activity and the brain a the Panum Institute
  • The background for our study were that epidemiological studies has found a correlation between exposure to prenatal infection and later development of neurological-related diseases like Cerebral Palsy and Schizophrenia.
  • But the relationship between the level of spontaneous locomotion and prenatal exposure to infection is less studied and illuminated
  • So our aim of this study were to investigate whether prenatal infection induces changes in the level of spontaneous locomotion in young mice?
  • And if a gender difference in the level of locomotion is present, in the same mice strain
  • We injected 3 progressive doses of LPS into the pregnant dam at GD 18, 19 and 20 and used the offspring as our prenatally infected intervention group. In addition did we buy two groups of 8 mice each, consisting of male and female mice respectively and these were our control groups.
  • Following separated we the 3 groups in 6 subgroups: a wheel-running group and an control-group that were placed in normal cages.Both sub-groups did the PRÆ open-field test, and were then placed in their respective cages for 14-21 days and lastly did all the groups complete the POST open-field test
  • If we look closer to the travelled distance parameter on the PRE and POST test we notice that the Con-female group travelled a significant longer distance than the LPS group, on both the PRE and POST test-day.Also it is noteworthy that no statistical change is present in the LPS group from the PRE to POST test, but such a difference is visible in the Con-female group. In addition, we can see that there is no statistical gender-difference on the PRE test, but there is on the POST test.
  • If we then look into the results from the voluntary wheel-running period we find that there is no statistical difference between the travelled distance per day between the LPS and Con-female group in a 12 day period.On the contrary we now see a highly statistical significant gender difference between Con-male and Con-female groups, and also between the LPS and the male control-group.
  • From our conducted study it can be concluded that we prove …
  • I would like to mention a couple of methodological considerations from our study.In our applied wheel-running setup is turned out to be a bit of a problem that the mice would get their nest-material stuck between the wheel and the walls of the cage. This caused the resistance to be increased or the wheel to be totally blocked. So this would influence the daily recorded kilometers. I tried to exclude those days were I had substantiate reason to believe that this was the case, but no matter what it is still a source of uncertainty.
  • Whether the LPS treatment has caused an activating of the innate immune defense is crucial for the interpretation of our results.Subsequent immunohistochemical analysis by Hanne Mikkelsen from ICMM showed positive Iba1 cells, 12 weeks after the treatment, when she stained tissue from the intestine.Iba1 is a cytoplasmic cytokine-induced calcium binding protein expressed in immune-related tissue, involved in makrophag activation and function. This does not definitive prove that nothing had happened, in that for example Stolp et al. report that the inflammatory response quickly disappears when the treatment has ended. And it is possible that the Iba1 antibody was not specific or good enough.
  • When I was reading the Danish newspaper, Weekendavisen, for about a week ago I ran into this interview with the Danish neuroscientist, Maiken Nedergaard from University of Rochester. She was cited to saying that: .. After reading the very interesting article I thought about an article by Stolp et al. that I had just finished a couple of days earlier
  • In that study they found that prenatal LPS treatment caused a significant increase in GFAP density in an animal-model, when they measured this in the adult animal. They took the GFAP density as evidence for that the density and maybe the numbers of astrocytes were increased.
  • So if prenatal LPS treatment causes an increase in the density of astrocytes, is there a functional difference in these animals, compared with normal wild-type? It has been proposed that the astrocyte is part of a tripartite synapse, where is can modulate and effect the neural transmission, by taking up NT and releasing GT.So it would be appealing to investigate if an in vivo difference in astrocyte and neuronal activity is present in the LPS treated mice.
  • Standford et al. reports that the last round of DNA synthesis of the precursor cells that are to become the Layer V neurons happens on GD 15-18.The inflammatory response following bacterial infection is believed to be able to impair and disrupt the normal cellular developmentThus it would be interesting to investigate whether timing of LPS treatment makes a difference to the extend of damage in for example the corticospinal tract.
  • Bachelor's Defense

    1. 1. Department of NEXS Copenhagen, 24th of June, 2013 Rune Rasmussen Department of Physical activity and the Brain Bachelor defense Spontaneous locomotion in young NMRI mice following motherly LPS treatment
    2. 2. Department of NEXS Background Copenhagen, 24th of June, 2013 (Boksa, 2010)
    3. 3. Department of NEXS Background Copenhagen, 24th of June, 2013 Spontaneous locomotion ?
    4. 4. Department of NEXS Aim of study Induces prenatal infection changes in the level of spontaneous locomotion ? Do the level of spontaneous locomotion differ between genders in NMRI mice? Copenhagen, 24th of June, 2013
    5. 5. Department of NEXS Aim of study Induces prenatal infection changes in the level of spontaneous locomotion ? Do the level of spontaneous locomotion differ between genders in NMRI mice? Copenhagen, 24th of June, 2013
    6. 6. Department of NEXS Groups Copenhagen, 24th of June, 2013 n = 7 ♀ n = 8 ♀ n = 8 ♂ Con-male Con-female $$ $$
    7. 7. Department of NEXS Protocol Copenhagen, 24th of June, 2013 PREopen-field PREopen-field POST open-field POST open-field
    8. 8. Department of NEXS Open-field tests Copenhagen, 24th of June, 2013 LPS mice travelled a shorter distance in open-field test Con-male only different in POST test * different from PRE † different from LPS (p<0.05) and ‡‡ different from Con-male (p < 0.01)
    9. 9. Department of NEXS Voluntary wheel-running LPS and con-female were not different in wheel-running Con-male ran the least Copenhagen, 24th of June, 2013 ** Different from Con-male (p < 0.01)
    10. 10. Department of NEXS And the presence of gender difference in basal locomotion level in young NMRI mice Conclusion Equivocal evidence that prenatal infection impairs the level of spontaneous locomotion Open-field tests and voluntary wheel-running is two less inter- correlated behavioral measures for spontaneous locomotion Copenhagen, 24th of June, 2013
    11. 11. Department of NEXS Wheel-running uncertainties Copenhagen, 24th of June, 2013
    12. 12. Department of NEXS Immune activation or not? Iba-1 staining* => No difference 12 weeks after treatment *Immunohistochemistry conducted by Hanne Mikkelsen, ICMMCopenhagen, 24th of June, 2013 Inflammatory response disappears quickly after ended treatment (Stolp et al. 2005) LPS Con
    13. 13. Department of NEXS Future work in astrocytes (Weekendavisen, 14th of June, 2013) (Maiken Nedergaard, M.D, D.M.Sc) Copenhagen, 24th of June, 2013
    14. 14. Department of NEXS (Stolp et al. 2005) Copenhagen, 24th of June, 2013 Increased astrocyte density Astrocytes
    15. 15. Department of NEXS Impaired neuron-glia interaction? in vivo imaging of astrocyte- and neuronal activity (Perea et al. Trends in neuroscience, 2009) (SmithLab, University of Stanford, 2013) Copenhagen, 24th of June, 2013
    16. 16. Department of NEXS The corticospinal tract LPS treatment GD 11-13 vs. 18-20? (Wikipédia, 2013)Copenhagen, 24th of June, 2013 Last round of DNA synthesis of layer V precursor cells GD 15-18 (Standford et al. 1992)
    17. 17. Wrong interpretation of POWER Statistical power is the probability for not committing a type II error (False negative) Significance level is the probability for committing a type I error (False positive) => Makes no sense to apply the power-test on significant results! Department of NEXS Copenhagen, 24th of June, 2013
    18. 18. Department of NEXS Rune Rasmussen Department of Nutrition, Exercise and Sports Copenhagen, 24th of June, 2013 Bachelor defence
    19. 19. Enhedens navn Copenhagen, 24th of June, 2013 How does the LPS work?
    20. 20. Department of NEXS Peak speed – 3 groups Copenhagen, 24th of June, 2013
    21. 21. Enhedens navn Inner zone entrances– 3 groups Copenhagen, 24th of June, 2013
    22. 22. Department of NEXS Copenhagen, 24th of June, 2013 Rearing's – 3 groups
    23. 23. Department of NEXS Copenhagen, 24th of June, 2013 Distance – 6 groups
    24. 24. Enhedens navn Peak speed – 6 groups Copenhagen, 24th of June, 2013
    25. 25. Enhedens navn Inner zone entrances – 6 groups Copenhagen, 24th of June, 2013
    26. 26. Enhedens navn Rearing's – 6 groups Copenhagen, 24th of June, 2013
    27. 27. Department of NEXS Copenhagen, 24th of June, 2013 Voluntary wheel-running – 12 days
    28. 28. Department of NEXS Weight – treated mice Copenhagen, 24th of June, 2013
    29. 29. Enhedens navn Weight – offspring Copenhagen, 24th of June, 2013

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