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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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Selective vulnerability of αOFF retinal ganglion cells during onset of autoimmune optic neuritis. Neuroscience. 2018 Nov 21;393:258-272. doi: 10.1016/j.neuroscience.2018.07.040. Epub 2018 Aug 1.

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Genetic ablation of NFAT5/TonEBP in smooth muscle cells impairs flow- and pressure-induced arterial remodeling in mice. FASEB J. 2018 Nov 1:fj201801594R. doi: 10.1096/fj.201801594R. [Epub ahead of print]

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Synaptic entrainment of ectopic action potential generation in hippocampal pyramidal neurons.  J Physiol. 2018 Nov;596(21):5237-5249. doi: 10.1113/JP276720. Epub 2018 Sep 19.

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The Long Noncoding RNA Cancer Susceptibility 9 and RNA Binding Protein Heterogeneous Nuclear Ribonucleoprotein L Form a Complex and Coregulate Genes Linked to AKT Signaling. Hepatology. 2018 Nov;68(5):1817-1832. doi: 10.1002/hep.30102. Epub 2018 Oct 12.

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Reduction of Transplant Vasculopathy by Intraoperative Nucleic Acid-based Therapy in a Mouse Aortic Allograft Model. Thorac Cardiovasc Surg. 2018 Oct 23. doi: 10.1055/s-0038-1673633. [Epub ahead of print]

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Early appearance and spread of fast ripples in the hippocampus in a model of cortical traumatic brain injury. J Neurosci. 2018 Oct 17;38(42):9034-9046. doi: 10.1523/JNEUROSCI.3507-17.2018. Epub 2018 Sep 6.

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High-fat diet suppresses the positive effect of creatine supplementation on skeletal muscle function by reducing protein expression of IGF-PI3K-AKT-mTOR pathway. PLoS One. 2018 Oct 4;13(10):e0199728. doi: 10.1371/journal.pone.0199728. eCollection 2018.

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Alcohol reduces muscle fatigue through atomistic interactions with nicotinic receptors. Commun Biol. 2018 Oct 3;1:159. doi: 10.1038/s42003-018-0157-9. eCollection 2018.

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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 Oct;92(10):3191-3205. doi: 10.1007/s00204-018-2295-8. Epub 2018 Aug 24.

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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 Oct 1;315(4):F861-F869. doi: 10.1152/ajprenal.00633.2017. Epub 2018 Mar 7.

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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 Sep 10;143(18):4273-4282. doi: 10.1039/c8an00659h. Epub 2018 Jul 20.

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Recent advances in hippocampal structure and function. Cell Tissue Res. 2018 Sep;373(3):521-523. doi: 10.1007/s00441-018-2913-z. Epub 2018 Aug 20. doi: 10.1007/s00441-018-2913-z. 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 Sep;373(3):671-691. doi: 10.1007/s00441-018-2881-3. Epub 2018 Aug 15. Review.

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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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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]


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