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Semelhante a Neurological effects of space radiation.ppt97 2003
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Neurological effects of space radiation.ppt97 2003
- 2. NEUROLOGICAL EFFECTS OF SPACE RADIARTION 12/31/2012 gasabeh.com gasabeh47@gmail.com 2
- 5. INTRODUCTION -mono-source -Tumor control -Controlled beam -Gamma/X rays -Uniparticle -High dose(>20Gy) -Local areas -Steep D-R curve -Leukoencephalopathy -Myelopathy -Month time lag -Edema,BBB breakdown, Inflammation,necrosis 12/31/2012 gasabeh.com gasabeh47@gmail.com 5
- 7. INTRODUCTION Leukoencephalopathy in a 14-year-old girl with Radiation myelopathy after radioactive previous ALL due to the previous combinationgasabeh.com of 12/31/2012 7 chemotherapy and radiation therapy. gasabeh47@gmail.com iodine therapy for spine metastasis
- 8. INTRODUCTION -Multi-source -Uncontrolled beam -Multi-particle -Low dose(<2 Gy) -Whole body -Slow effect 12/31/2012 gasabeh.com gasabeh47@gmail.com 8
- 9. INTRODUCTION • Cosmic rays from space hit Earth's atmosphere all the time. When a highenergy cosmic ray enters the atmosphere, it can cause an "air shower". The cosmic ray hits a molecule in the atmosphere and "breaks up", producing lots more subatomic particles. A real air shower can make millions of particles. This picture shows a simple version of an air shower. The cosmic ray (in red, at the top) makes lots of other particles, many with odd names. The subatomic particles shown here include protons (green), neutrons (orange), pions (yellow), muons (purple), photons (blue), and electrons & positrons (pink). 12/31/2012 gasabeh.com gasabeh47@gmail.com 9
- 12. NEURAL PRECURSOR CELLS Immature-Low dose(<1)-Divided throughout life in 12/31/2012 gasabeh.com mammals gasabeh47@gmail.com 12
- 13. NEURAL PRECURSOR CELLS 12/31/2012 NRP:Neuronal Restricted Precursor Cell gasabeh.com 13 GRP:Glial gasabeh47@gmail.com Restricted Precursor cell
- 15. NEURAL PRECURSOR CELLS Fike and others have demonstrated that X-ray doses of 2-5 Gy cause substantial apoptosis of NPCs and continued reduction in the production of immature neurons 12/31/2012 gasabeh.com 15 1Gy:is defined as the absorption of one joule of such energy by one kilogram of matter (usually human tissue) gasabeh47@gmail.com
- 16. CELLULAR LEVEL RESPONSES Porosomes at the presynaptic membrane in synaptosomes from rat brain neurons. (a) Electron micrograph of a single synaptosome full of 40–50 nm synaptic vesicles.6 Scale bar =100 nm. (b) Atomic force microscopy (AFM) micrograph of an isolated synaptosome from rat brain. Scale bar=100 nm. (c) AFM micrograph of a 10 nm porosome complex at the presynaptic membrane of an isolated synaptosome. Note the central plug and the eightprotein densities.8 (d) Electron microscopy (EM) micrograph of a 10 nm cup-shaped neuronal porosome with a central plug (arrowhead) and a 50 nm docked synaptic vesicle (SV).6 (e) AFM micrograph of an insideout presynaptic membrane prepared from However, isolated rat synaptosomes show decreased Na+uptake after 1 Gy of gamma rays (Mullin et al., 1986) and some tissue culture gasabeh.com alterations in Ca2+ transport after 1-4 cells exhibit 12/31/2012 16 Gy of electrons (Todd and Mikkelsen, gasabeh47@gmail.com 1994) suggesting sensitivity of ion channels.
- 17. CELLULAR LEVEL RESPONSES Growth of new processes (neuritogenesis) from neurons in chick retinal explants 12/31/2012 gasabeh.com 17 is also sensitive to iron ions at doses below 0.5 Gy (Vazquez et al., 1994). gasabeh47@gmail.com
- 18. ELECTRICAL OUTPUT OF NERVE Significant decreases in the frequency and amplitude of spikes were observed in most brain regions after 4 – 5 Gy at times up to 6 hr, but the hippocampus exhibited hyperexcitability along with changes in spike train organization that may be associated with inhibitory neuron malfunction (Monnier and Krupp,in rabbits 1962). 12/31/2012 gasabeh.com At higher doses (9 Gy) all activity was suppressed. gasabeh47@gmail.com 18
- 19. ELECTRICAL OUTPUT OF NERVE The pedal-pleural ganglion of the sea slug Aplysia exhibited increased 12/31/2012 excitability after 10 Gy of gamma gasabeh.com rays (Clatworthy et al., 1999). gasabeh47@gmail.com 19
- 20. BEHAVIORAL AND COGNITIVE EFFECTS Morris water maze and Barnes maze experiments indicate that spatial memory and learning are inhibited by doses as low as 0.1 Gy of iron ions (Shukitt-Hale et al., 2000; Raber et al., 2004-in rat&mice). These behaviors are believed to be largely associated with the hippocampus. 12/31/2012 gasabeh.com gasabeh47@gmail.com 20
- 21. BEHAVIORAL AND COGNITIVE EFFECTS In Israel, a large cohort of children (~20,000 of average age 7 years) were treated with a mean dose of 1.3 Gy X-rays to cause depilation of the scalp in order to facilitate treatment of tinea capitis fungal infections. These children later showed poorer outcomes in high school aptitude and IQ performance and more frequent psychiatric disturbances in later life. (Ron et al., 1982). 12/31/2012 gasabeh.com gasabeh47@gmail.com 21
- 22. BEHAVIORAL AND COGNITIVE EFFECTS A group of 6-18 month-old Swedish children treated for cutaneous hemangioma (strawberry birthmarks) on the head were followed-up at the time of comprehensive testing prior to military enlistment (age 18 – 19 years). They showed cognitive impairments at doses above 0.1 Gy and up to 32% decreases in high school attendance (corrected for social influences) after frontal lobe X-ray doses > 0.25 Gy (Hall et al., 2004). 12/31/2012 gasabeh.com gasabeh47@gmail.com 22