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Institut für Physiologie und Pathophysiologie

Nonlinear Microscopy

Figure 1: SHG signals from myofibrils change under rotation of the excitation laser polarization

Second Harmonic Generation

Second harmonic generation (or frequency doubling) is an effect that can be observed in certain nonlinear optical media, which emit radiation at a doubled frequency 2w when excited by an external electric field of the frequency w. The effect is well known for a number of crystals like quartz, but was also discovered for some biological structures like collagen or skeletal muscle myosin-II.

 

We are interested in the physical properties of second harmonic generation in these biological structures and applications for tissue imaging. The SHG signal intensity, for example, depends on the fiber orientation and the polarization of the incident light. Theoretical predictions for this dependency can be derived from standard equations considering crystal symmetries and then be tested with our experimental setup.

Figure 2: Two-photon excited fluorescence of Bodipy-Fl labeled actin in skeletal muscle

Multiphoton Fluorescence

Two or more photons of an infrared laser can be absorbed simultaneously by a fluorescent molecule to promote it to an excited state. The emission wavelength is the same as for standard single photon excitation.

 

As the effect of multi-photon excitation needs high energy densities, it occures mainly in the small center of the laser focus. Fluorescence is limited to this spot, which provides multi-photon microscopes with inherent high resolution. The main advantage over confocal microscopes is the higher resolution in deep tissue layers.

 


Neue Publikationen

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Synaptic entrainment of ectopic action potential generation in hippocampal pyramidal neurons. J Physiol. 2018 Aug 24. doi: 10.1113/JP276720. [Epub ahead of print]

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Possible neurotoxicity of the anesthetic propofol: evidence for the inhibition of complex II of the respiratory chain in area CA3 of rat hippocampal slices. Arch Toxicol. 2018 Aug 24. doi: 10.1007/s00204-018-2295-8. [Epub ahead of print]

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Metabolic modulation of neuronal gamma-band oscillations. Pflugers Arch2018 Sep;470(9):1377-1389. doi: 10.1007/s00424-018-2156-6. Epub 2018 May 28.

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Recent advances in hippocampal structure and function. Cell Tissue Res. 2018 Aug 20. doi: 10.1007/s00441-018-2913-z. [Epub ahead of print] Editorial. No abstract available.

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Electrical coupling between hippocampal neurons: contrasting roles of principal cell gap junctions and interneuron gap junctions. Cell Tissue Res. 2018 Aug 15. doi: 10.1007/s00441-018-2881-3. [Epub ahead of print] Review.

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Persistent sodium current modulates axonal excitability in CA1 pyramidal neurons. J Neurochem. 2018 Aug;146(4):446-458. doi: 10.1111/jnc.14479. Epub 2018 Aug 1.

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Selective vulnerability of αOFF retinal ganglion cells during onset of autoimmune optic neuritis. Neuroscience. 2018 Jul 31. pii: S0306-4522(18)30515-3. doi: 10.1016/j.neuroscience.2018.07.040. [Epub ahead of print]

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Strategy for marker-based differentiation of pro- and anti-inflammatory macrophages using matrix-assisted laser desorption/ionization mass spectrometry imaging. Analyst. 2018 Jul 20. doi: 10.1039/c8an00659h. [Epub ahead of print]

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Improving electrical properties of iPSC-cardiomyocytes by enhancing Cx43 expression. J Mol Cell Cardiol. 2018 Jul;120:31-41. doi: 10.1016/j.yjmcc.2018.05.010. Epub 2018 May 16.

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Role of CD40 and ADAMTS13 in von Willebrand factor-mediated endothelial cell-platelet-monocyte interaction. Proc Natl Acad Sci U S A. 2018 Jun 12;115(24):E5556-E5565. doi: 10.1073/pnas.1801366115. Epub 2018 May 23.

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The VAMP-associated protein VAPB is required for cardiac and neuronal pacemaker channel function. FASEB J. 2018 Jun 7:fj201800246R. doi: 10.1096/fj.201800246R. [Epub ahead of print]

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The lncRNA CASC9 and RNA binding protein HNRNPL form a complex and co-regulate genes linked to AKT signaling. Hepatology. 2018 May 23. doi: 10.1002/hep.30102. [Epub ahead of print]

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Early Blood-Brain Barrier Disruption in Ischemic Stroke Initiates Multifocally Around Capillaries/Venules. Stroke. 2018 Jun;49(6):1479-1487. doi: 10.1161/STROKEAHA.118.020927. Epub 2018 May 14.

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Impact of carbonylation on glutathione peroxidase-1 activity in human hyperglycemic endothelial cells. Redox Biol. 2018 Jun;16:113-122. doi: 10.1016/j.redox.2018.02.018. Epub 2018 Mar 1.

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Endothelial progenitor cells accelerate endothelial regeneration in an in vitro model of Shigatoxin-2a-induced injury via soluble growth factors. Am J Physiol Renal Physiol. 2018 Mar 7. doi: 10.1152/ajprenal.00633.2017. [Epub ahead of print]


Institut für
Physiologie und Pathophysiologie

Universität Heidelberg

Im Neuenheimer Feld 326

69120 Heidelberg

Telefon:+49 6221 54-4035
Telefax:+49 6221 54-4038
E-Mail:sekretariat.hecker@
physiologie.uni-heidelberg.de