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163 results on '"Kao, Joseph P.Y."'

20. Superoxide Flashes in Single Mitochondria

Author

Wang, Wang, Fang, Huaqiang, Groom, Linda, Cheng, Aiwu, Zhang, Wanrui, Liu, Jie, Wang, Xianhua, Li, Kaitao, Han, Peidong, Zheng, Ming, Yin, Jinhu, Wang, Weidong, Mattson, Mark P., Kao, Joseph P.Y., Lakatta, Edward G., Sheu, Shey-Shing, Ouyang, Kunfu, Chen, Ju, Dirksen, Robert T., and Cheng, Heping

Published
2008
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23. Hydrophilic anilinogeranyl diphosphate prenyl analogues are RAS function inhibitors

Author

Roberts, Michael J., Troutman, Jerry M., Chehade, Kareem A.H., Cha, Hyuk C., Kao, Joseph P.Y., Xiaoquin Huang, Chang-Guo Zhan, Peterson, Yuri K., Spielmann, H. Peter, Subramanian, Thangaiah, Kamalakkannan, Srinivasan, and Andres, Douglas A.

Subjects
Pyrophosphates -- Chemical properties, Pyrophosphates -- Structure, Protein kinases -- Structure, Protein kinases -- Chemical properties, Xenopus -- Research, Methyltransferases -- Structure, Methyltransferases -- Chemical properties, Biological sciences, Chemistry
Abstract

An Xenopus laevis oocyte whole-cell model system is applied to investigate whether anilinogeranyl diphosphate analogues of similar shape and size, but with varying hydrophobicity from that of the farnesyl transferase (FTase) substrate farnesyl diphosphate (FPP), could ablate the biological function of H-Ras. It was concluded that H-Ras biological function needs atleast a minimum lipophilicity of the prenyl group to permit major interactions downstream of the C-terminal processed H-Ras protein.

Published
2006

24. Caged vanilloid ligands for activation of TRPV1 receptors by 1- and 2-photon excitation

Author

Gover, Tony D., Muralidharan, Sukumaran, Auston, Darryl A., Weinreich, Daniel, and Kao, Joseph P.Y.

Subjects
Capsaicin -- Chemical properties, Capsaicin -- Structure, Photolysis -- Analysis, Nociceptors -- Research, Biological sciences, Chemistry
Abstract

The synthesis and biological application of two caged vanilloids that is biogically inert precursors that, when photolyzed, release bioactive vanilloid ligands is reported. In combination with 1- or 2- photon excitation, caged vanilloids are a powerful tool for probing morphologically distinct structures of nociceptive sensory neurons with high spatial and temporal precision.

Published
2006

25. Long-term potentiation of exogenous glutamate responses at single dendritic spines

Author

Bagal, Ashish A., Kao, Joseph P.Y., Tang, Cha-Min, and Thompson, Scott M.

Subjects
Hippocampus (Brain) -- Research, Brain -- Research, Cells -- Research, Science and technology
Abstract

Long-term increases in the strength of excitatory transmission at Schaffer collateral-CA1 cell synapses of the hippocampus require the insertion of new [alpha]-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) into the synapse, but the kinetics of this process are not well established. Using microphotolysis of caged glutamate to activate receptors at single dendritic spines in hippocampal CA1 cells, we report the long-lasting potentiation of AMPAR-mediated currents with only a single pairing of photoreleased glutamate and brief postsynaptic depolarization. This potentiation was N-methyl-o-aspartate receptor (NMDAR)-dependent and was reversed with low-frequency photostimulation in an NMDAR-dependent manner, suggesting that it is mediated by the same mechanism(s) as conventional synaptic long-term potentiation. Potentiation of photolytic responses developed rapidly in a stepwise manner after a brief and variable delay ( synaptic plasticity | hippocampus | plasticity

Published
2005

33. Generation of calcium oscillations in fibroblasts by positive feedback between calcium and IP3

Author

Harootunian, Alec T., Kao, Joseph P.Y., Paranjape, Suman, and Tsien, Roger Y.

Subjects
Calcium ions -- Physiological aspects -- Research, Inositol phosphates -- Physiological aspects -- Research, Fibroblasts -- Research -- Physiological aspects, Calcium, Dietary -- Physiological aspects -- Research, Science and technology, Physiological aspects, Research
Abstract

A wide variety of nonexcitable cells generated repetitive transient increases in cytosolic calcium oion concentration ([[Ca.sup.2+]sub.i]) when stimulated with agonists that engage the phosphoinositide signalling pathway. Current theories regarding the [...]

Published
1991

37. Calcium waves driven by 'sensitization” wave-fronts

Author

Keller, Markus, Kao, Joseph P.Y., Egger, Marcel, Niggli, Ernst, Keller, Markus, Kao, Joseph P.Y., Egger, Marcel, and Niggli, Ernst

Abstract

Objective: Cellular Ca2+ waves are understood as reaction-diffusion systems sustained by Ca2+-induced Ca2+ release (CICR) from Ca2+ stores. Given the recently discovered sensitization of Ca2+ release channels (ryanodine receptors; RyRs) of the sarcoplasmic reticulum (SR) by luminal SR Ca2+, waves could also be driven by RyR sensitization, mediated by SR overloading via Ca2+ pump (SERCA), acting in tandem with CICR. Methods: Confocal imaging of the Ca2+ indicator fluo-3 was combined with UV-flash photolysis of caged compounds and the whole-cell configuration of the patch clamp technique to carry out these experiments in isolated guinea pig ventricular cardiomyocytes. Results: Upon sudden slowing of the SERCA in cardiomyocytes with a photoreleased inhibitor, waves indeed decelerated immediately. No secondary changes of Ca2+ signaling or SR Ca2+ content due to SERCA inhibition were observed in the short time-frame of these experiments. Conclusions: Our findings are consistent with Ca2+ loading resulting in a zone of RyR ‘sensitization' traveling within the SR, but inconsistent with CICR as the predominant mechanism driving the Ca2+ waves. This alternative mode of RyR activation is essential to fully conceptualize cardiac arrhythmias triggered by spontaneous Ca2+ release

Published
2017

38. [super 2]H, [super 15]N-Substituted nitroxides a sensitive probes for electron paramagnetic resonance imaging

Author

Burks, Scott R., Bakhshai, Justin, Makowsky, Mallory A., Muralidharan, Sukumaran, Pei Tsai, Rosen, Gerald M., and Kao, Joseph P.Y.

Subjects
Electron paramagnetic resonance spectroscopy -- Usage, Methyl groups -- Structure, Methyl groups -- Chemical properties, Nitrogen oxide -- Chemical properties, Pyrrole -- Chemical properties, Substitution reactions -- Analysis, Biological sciences, Chemistry
Abstract

3-Carboxy-2,2,5,5-tetra([super 2][H.sub.3])methyl-1-(3,4,4-[super 2][H.sub.3],1-[super 15]N) pyrrolidinyloxyl is prepared for increasing the sensitivity of [O.sub.2] measurement by EPR imaging. The new isotopically substituted nitroxide has displayed increased sensitivity to changes in [O.sub.2] concentration, which has enabled accurate [O.sub.2] measurement in tissues by using electron paramagnetic resonance imaging.

Published
2010

39. The effect of structure on nitroxide EPR spectral linewidth

Author

Burks, Scott R., Bowman, Michael K., Kao, Joseph P.Y., Rosen, Gerald M., Yaffe, Zachary A., Makowsky, Mallory A., Hoggle, Chad, Muralidharan, Sukumaran, and Pei Tsai

Subjects
Nitrogen compounds -- Structure, Nitrogen compounds -- Chemical properties, Electron paramagnetic resonance -- Usage, Biological sciences, Chemistry
Abstract

A framework is developed for designing narrow-line nitroxides in order to understand the narrow line width of 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxyl. Nitroxide (4-carboxymethylidene-2,2,6,6-tetramethyl-1-piperidinyloxy), as a prototype, has allowed a variety of structural diversity such a nitroxide that can target tissue compartments for in vivo EPR imaging.

Published
2010

40. Interaction of radical pairs through-bond and through-space: scope and limitations of the point-dipole approximation in electron paramagnetic resonance spectroscopy

Author

Riplinger, Christoph, Kao, Joseph P.Y., Rosen, Gerald M., Kathirvelu, Velavan, Eaton, Gareth R., Eaton, Sandra S., Kutateladze, Andrei, and Neese, Frank

Subjects
Magnetic dipoles -- Analysis, Electron paramagnetic resonance spectroscopy -- Usage, Pyrrole -- Chemical properties, Pyrrole -- Structure, Tertiary butyl compounds -- Structure, Tertiary butyl compounds -- Chemical properties, X-ray crystallography -- Usage, Chemistry
Abstract

Electron paramagnetic resonance (EPR) and X-ray crystallography are used for studying a model system (2,2',5,5'-tetra(tert-butyl)-4,4'-bis(ethoxy-carbonyl)-3,3'-bipyrrolyl-1,1'-dioxyl) in order understand the scope and limitations of the point-dipole model in EPR spectroscopy. The results have shown that even very modest amounts of spin delocalization has caused major deviations from pure point-dipole behavior and has consequently caused the EPR derived distances to deviate from the N-O midpoint distance by up to several angstroms.

Published
2009

41. Photochemical gating of intracellular [Ca.sup.2+] release channels

Author

Auston, Darryl A., Freilich, David A., Muralidharan, Sukumaran, Sobie, Eric A., and Kao, Joseph P.Y.

Subjects
Calcium compounds -- Structure, Calcium compounds -- Optical properties, Photolysis -- Analysis, Xanthine -- Properties, Chemistry
Abstract

The design, synthesis and the biological utility of BiNiX, a photoactivatable ryanodine receptor (RyR) agonist, is reported. Focal photolysis has permitted activation of RyRs with high spatiotemporal precision, thereby indicating that BiNiX is a unique tool for probing RyR function in living cells.

Published
2007

42. Nonpolar substitution at the C-terminus of the prion protein, a mimic of the glycosylphosphatidylinositol anchor, partially impairs amyloid fibril formation

Author

Breydo, Leonid, Ying Sun, Makarava, Natallia, Cheng-I Lee, Novitskaia, Vera, Bocharova, Olga, Kao, Joseph P.Y., and Baskakov, Ilia V.

Subjects
Prions -- Chemical properties, Prions -- Structure, Hydrophobic effect -- Research, Muscle contraction -- Abnormalities, Muscle contraction -- Research, Biological sciences, Chemistry
Abstract

The recombinant prion protein (PrP) is modified with an N-myristoylamidomaleimidyl group, which serves as a membrane anchor, in order to test the extent to which a long hydrophobic chain at the C-terminus affects the intrinsic amyloidogenic propensity of PrP. The results have shown that, despite a bulky hydrophobic moiety at C-terminus, myristoylated PrP can incorporate into fibrillar structure.

Published
2007

47. In vivo EPR imaging of differential tumor targeting using cis-3,4-di(acetoxymethoxycarbonyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxyl

Author

Redler, Gage, Barth, Eugene D., Bauer, Kenneth S., Kao, Joseph P.Y., Rosen, Gerald M., and Halpern, Howard J.

Subjects
Mice, Inbred C3H, Metabolic Clearance Rate, Fibrosarcoma, Electron Spin Resonance Spectroscopy, Reproducibility of Results, Magnetic Resonance Imaging, Sensitivity and Specificity, Article, Molecular Imaging, Cyclic N-Oxides, Diagnosis, Differential, Mice, Cell Line, Tumor, Animals, Tissue Distribution
Abstract

Electron paramagnetic resonance spectroscopy promises quantitative images of important physiologic markers of animal tumors and normal tissues, such as pO(2), pH, and thiol redox status. These parameters of tissue function are conveniently reported by tailored nitroxides. For defining tumor physiology, it is vital that nitroxides are selectively localized in tumors relative to normal tissue. Furthermore, these paramagnetic species should be specifically taken up by cells of the tumor, thereby reporting on both the site of tumor formation and the physiological status of the tissue. This study investigates the tumor localization of the novel nitroxide, cis-3,4-di(acetoxymethoxycarbonyl)-2,2,5,5-tetramethyl-1-pyrrolidin-yloxyl 3 relative to the corresponding di-acid 4.We obtained images of nitroxide 3 infused intravenously into C3H mice bearing 0.5-cm(3) FSa fibrosarcoma on the leg, and compared these with images of similar tumors infused with nitroxide 4.The ratio of spectral intensity from within the tumor-bearing region to that of normal tissue was higher in the mice injected with 3 relative to 4.This establishes the possibility of tumor imaging with a nitroxide with intracellular distribution and provides the basis for EPR images of animal models to investigate the relationship between crucial aspects of tumor microenvironment and malignancy and its response to therapy.

Published
2013

49. Calcium Movement in Cardiac Mitochondria

Author

Boyman, Liron, primary, Williams, George S.B., additional, Chikando, Aristide C., additional, Khairallah, Ramzi J., additional, Kettlewell, Sarah, additional, Ward, Christopher W., additional, Smith, Godfrey L., additional, Kao, Joseph P.Y., additional, and Lederer, W.J., additional

Published
2015
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