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Zhao L, Arias SL, Zipfel W, Brito IL, Yeo J. Coarse-grained modeling and dynamics tracking of nanoparticles diffusion in human gut mucus. Int J Biol Macromol 2024; 267:131434. [PMID: 38614182 DOI: 10.1016/j.ijbiomac.2024.131434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 02/23/2024] [Accepted: 04/04/2024] [Indexed: 04/15/2024]
Abstract
The gastrointestinal (GI) tract's mucus layer serves as a critical barrier and a mediator in drug nanoparticle delivery. The mucus layer's diverse molecular structures and spatial complexity complicates the mechanistic study of the diffusion dynamics of particulate materials. In response, we developed a bi-component coarse-grained mucus model, specifically tailored for the colorectal cancer environment, that contained the two most abundant glycoproteins in GI mucus: Muc2 and Muc5AC. This model demonstrated the effects of molecular composition and concentration on mucus pore size, a key determinant in the permeability of nanoparticles. Using this computational model, we investigated the diffusion rate of polyethylene glycol (PEG) coated nanoparticles, a widely used muco-penetrating nanoparticle. We validated our model with experimentally characterized mucus pore sizes and the diffusional coefficients of PEG-coated nanoparticles in the mucus collected from cultured human colorectal goblet cells. Machine learning fingerprints were then employed to provide a mechanistic understanding of nanoparticle diffusional behavior. We found that larger nanoparticles tended to be trapped in mucus over longer durations but exhibited more ballistic diffusion over shorter time spans. Through these discoveries, our model provides a promising platform to study pharmacokinetics in the GI mucus layer.
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Affiliation(s)
- Liming Zhao
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA
| | - Sandra L Arias
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Warren Zipfel
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Ilana L Brito
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
| | - Jingjie Yeo
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA.
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2
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Affiliation(s)
- Warren Zipfel
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Chris Xu
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Elliot Elson
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, Missouri 63110, United States
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
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McCoy MG, Wei JM, Choi S, Goerger JP, Zipfel W, Fischbach C. Collagen Fiber Orientation Regulates 3D Vascular Network Formation and Alignment. ACS Biomater Sci Eng 2018; 4:2967-2976. [PMID: 33435017 DOI: 10.1021/acsbiomaterials.8b00384] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Alignment of collagen type I fibers is a hallmark of both physiological and pathological tissue remodeling. However, the effects of collagen fiber orientation on endothelial cell behavior and vascular network formation are poorly understood because of a lack of model systems that allow studying these potential functional connections. By casting collagen type I into prestrained (0, 10, 25, 50% strain), poly(dimethylsiloxane) (PDMS)-based microwells and releasing the mold strain following polymerization, we have created collagen gels with varying fiber alignment as confirmed by structural analysis. Endothelial cells embedded within the different gels responded to increased collagen fiber orientation by assembling into 3D vascular networks that consisted of thicker, more aligned branches and featured elevated collagen IV deposition and lumen formation relative to control conditions. These substrate-dependent changes in microvascular network formation were associated with altered cell division and migration patterns and related to enhanced mechanosignaling. Our studies indicate that collagen fiber alignment can directly regulate vascular network formation and that culture models with aligned collagen may be used to investigate the underlying mechanisms ultimately advancing our understanding of tissue development, homeostasis, and disease.
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Affiliation(s)
- Michael G McCoy
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Jane M Wei
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States.,Biological Sciences, Cornell University, Ithaca, New York 14853, United States
| | - Siyoung Choi
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Julian Palacios Goerger
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Warren Zipfel
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Claudia Fischbach
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States.,Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
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4
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Wang J, Singh A, Zipfel W. A Protein Tag-Specific Aptamer for Use in Dstorm and Paint Based Super-Resolution Imaging. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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5
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Kushner M, Wang J, Ozer A, Ray J, Lis J, Zipfel W. High-Resolution Locus-Specific Mapping of Chromatin Contacts using Two-Photon Photoactivated DNA Cross-Linking. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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6
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Kushner M, Van Slyke A, Rinaldi F, Singh A, Lis J, Bogdanove A, Zipfel W. Examining Tale Protein Binding Kinetics and Site Competition using Single Molecule Imaging. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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7
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Wang J, Singh A, Cupri Rinaldi F, Lis J, Bogdanove A, Zipfel W. Visualizing Specific Genomic Loci using Fluorescently Labeled Transcription Activator-Like Effectors. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.3475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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8
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Wang J, Singh A, Ozer A, Lis J, Zipfel W. Super-Resolution Imaging of GFP Expressing Cells using Dye Labeled GFP Aptamers. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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9
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Durand M, Aggarwal A, Robinson B, Sooriakumaran P, Srivastava A, Zipfel W, Amiel J, Tewari A. La microscopie multiphotonique in vivo en temps reel : une imagerie prometteuse pour l’analyse histologique virutelle des tissus frais sans biopsie. Prog Urol 2013. [DOI: 10.1016/j.purol.2013.08.221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Bu P, Chen KY, Chen JH, Wang L, Walters J, Shin YJ, Goerger JP, Sun J, Witherspoon M, Rakhilin N, Li J, Yang H, Milsom J, Lee S, Zipfel W, Jin MM, Gümüşcedil ZH, Lipkin SM, Shen X. A microRNA miR-34a-regulated bimodal switch targets Notch in colon cancer stem cells. Cell Stem Cell 2013; 12:602-15. [PMID: 23642368 PMCID: PMC3646336 DOI: 10.1016/j.stem.2013.03.002] [Citation(s) in RCA: 280] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 11/25/2012] [Accepted: 03/04/2013] [Indexed: 12/15/2022]
Abstract
microRNAs regulate developmental cell-fate decisions, tissue homeostasis, and oncogenesis in distinct ways relative to proteins. Here, we show that the tumor suppressor microRNA miR-34a is a cell-fate determinant in early-stage dividing colon cancer stem cells (CCSCs). In pair-cell assays, miR-34a distributes at high levels in differentiating progeny, whereas low levels of miR-34a demarcate self-renewing CCSCs. Moreover, miR-34a loss of function and gain of function alter the balance between self-renewal versus differentiation both in vitro and in vivo. Mechanistically, miR-34a sequesters Notch1 mRNA to generate a sharp threshold response where a bimodal Notch signal specifies the choice between self-renewal and differentiation. In contrast, the canonical cell-fate determinant Numb regulates Notch levels in a continuously graded manner. Altogether, our findings highlight a unique microRNA-regulated mechanism that converts noisy input into a toggle switch for robust cell-fate decisions in CCSCs.
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Affiliation(s)
- Pengcheng Bu
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Kai-Yuan Chen
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Joyce Huan Chen
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Lihua Wang
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Jewell Walters
- Departments of Medicine, Genetic Medicine and Surgery, Weill Cornell Medical College, New York, NY 10021
| | - Yong Jun Shin
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Julian P. Goerger
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Jian Sun
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021, USA
| | - Mavee Witherspoon
- Departments of Medicine, Genetic Medicine and Surgery, Weill Cornell Medical College, New York, NY 10021
| | - Nikolai Rakhilin
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Jiahe Li
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Herman Yang
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Jeff Milsom
- Departments of Medicine, Genetic Medicine and Surgery, Weill Cornell Medical College, New York, NY 10021
| | - Sang Lee
- Departments of Medicine, Genetic Medicine and Surgery, Weill Cornell Medical College, New York, NY 10021
| | - Warren Zipfel
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Moonsoo M. Jin
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Zeynep H. Gümüşcedil
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021, USA
- HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and Cancer Center, Weill Cornell Medical College, New York, NY 10021, USA
| | - Steven M. Lipkin
- Departments of Medicine, Genetic Medicine and Surgery, Weill Cornell Medical College, New York, NY 10021
| | - Xiling Shen
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
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11
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Durand M, Aggarwal A, Robinson B, Sooriakumaran P, Groover S, Srivastava A, Mtui J, Brooks D, Flomenbaum D, Sterling J, Leung R, Herman M, Zipfel W, Webb W, Maxfield F, Mukherjee S, Arnaud P, Bensaid R, Mentine N, Rouscoff Y, Carpentier X, Chevallier D, Amiel J, Tewari AK. L’imagerie multiphotonique in vivo de la capsule prostatique : un outil prometteur pour la visualisation peropératoire des nerfs périprostatiques en temps réel. Prog Urol 2012. [DOI: 10.1016/j.purol.2012.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Degala S, Williams R, Zipfel W, Bonassar LJ. Calcium signaling in response to fluid flow by chondrocytes in 3D alginate culture. J Orthop Res 2012; 30:793-9. [PMID: 22042743 DOI: 10.1002/jor.21571] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 09/28/2011] [Indexed: 02/04/2023]
Abstract
Quantifying the effects of mechanical loading on the metabolic response of chondrocytes is difficult due to complicated structure of cartilage ECM and the coupled nature of the mechanical stimuli presented to the cells. In this study we describe the effects of fluid flow, particularly hydrostatic pressure and wall shear stress, on the Ca(2+) signaling response of bovine articular chondrocytes in 3D culture. Using well-established alginate hydrogel system to maintain spherical chondrocyte morphology, we altered solid volume fraction to change scaffold mechanics. Fluid velocities in the bulk of the scaffolds were directly measured via an optical technique and scaffold permeability and aggregate modulus was characterized to quantify the mechanical stimuli presented to cells. Ca(2+) signaling response to direct perfusion of chondrocyte-seeded scaffolds increased monotonically with flow rate and was found more directly dependent on fluid velocity rather than shear stress or hydrostatic pressure. Chondrocytes in alginate scaffolds responded to fluid flow at velocities and shear stresses 2-3 orders of magnitude lower than seen in previous monolayer studies. Our data suggest that flow-induced Ca(2+) signaling response of chondrocytes in alginate culture may be due to mechanical signaling pathways, which is influenced by the 3D nature of cell shape.
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Affiliation(s)
- Satish Degala
- Department of Biomedical Engineering, Cornell University, Olin Hall, Ithaca, New York 14853, USA
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13
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Shui B, Ozer A, Zipfel W, Sahu N, Singh A, Lis JT, Shi H, Kotlikoff MI. RNA aptamers that functionally interact with green fluorescent protein and its derivatives. Nucleic Acids Res 2011; 40:e39. [PMID: 22189104 PMCID: PMC3300005 DOI: 10.1093/nar/gkr1264] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Green Fluorescent Protein (GFP) and related fluorescent proteins (FPs) have been widely used to tag proteins, allowing their expression and subcellular localization to be examined in real time in living cells and animals. Similar fluorescent methods are highly desirable to detect and track RNA and other biological molecules in living cells. For this purpose, we have developed a group of RNA aptamers that bind GFP and related proteins, which we term Fluorescent Protein-Binding Aptamers (FPBA). These aptamers bind GFP, YFP and CFP with low nanomolar affinity and binding decreases GFP fluorescence, whereas slightly augmenting YFP and CFP brightness. Aptamer binding results in an increase in the pKa of EGFP, decreasing the 475 nm excited green fluorescence at a given pH. We report the secondary structure of FPBA and the ability to synthesize functional multivalent dendrimers. FPBA expressed in live cells decreased GFP fluorescence in a valency-dependent manner, indicating that the RNA aptamers function within cells. The development of aptamers that bind fluorescent proteins with high affinity and alter their function, markedly expands their use in the study of biological pathways.
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Affiliation(s)
- Bo Shui
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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14
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Jhaveri SJ, McMullen JD, Sijbesma R, Tan LS, Zipfel W, Ober CK. Direct three-dimensional microfabrication of hydrogels via two-photon lithography in aqueous solution. Chem Mater 2009; 21:2003-2006. [PMID: 20160917 PMCID: PMC2770197 DOI: 10.1021/cm803174e] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Shalin J Jhaveri
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY
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Tallini YN, Shui B, Greene KS, Deng KY, Doran R, Fisher PJ, Zipfel W, Kotlikoff MI. BAC transgenic mice express enhanced green fluorescent protein in central and peripheral cholinergic neurons. Physiol Genomics 2006; 27:391-7. [PMID: 16940431 DOI: 10.1152/physiolgenomics.00092.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The peripheral nervous system has complex and intricate ramifications throughout many target organ systems. To date this system has not been effectively labeled by genetic markers, due largely to inadequate transcriptional specification by minimum promoter constructs. Here we describe transgenic mice in which enhanced green fluorescent protein (eGFP) is expressed under the control of endogenous choline acetyltransferase (ChAT) transcriptional regulatory elements, by knock-in of eGFP within a bacterial artificial chromosome (BAC) spanning the ChAT locus and expression of this construct as a transgene. eGFP is expressed in ChAT(BAC)-eGFP mice in central and peripheral cholinergic neurons, including cell bodies and processes of the somatic motor, somatic sensory, and parasympathetic nervous system in gastrointestinal, respiratory, urogenital, cardiovascular, and other peripheral organ systems. Individual epithelial cells and a subset of lymphocytes within the gastrointestinal and airway mucosa are also labeled, indicating genetic evidence of acetylcholine biosynthesis. Central and peripheral neurons were observed as early as 10.5 days postcoitus in the developing mouse embryo. ChAT(BAC)-eGFP mice allow excellent visualization of all cholinergic elements of the peripheral nervous system, including the submucosal enteric plexus, preganglionic autonomic nerves, and skeletal, cardiac, and smooth muscle neuromuscular junctions. These mice should be useful for in vivo studies of cholinergic neurotransmission and neuromuscular coupling. Moreover, this genetic strategy allows the selective expression and conditional inactivation of genes of interest in cholinergic nerves of the central nervous system and peripheral nervous system.
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Affiliation(s)
- Yvonne N Tallini
- Biomedical Science Department, College of Veterinary Medicine, Ithaca, New York, USA
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17
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Abstract
Ca2+-induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR) occurs in smooth muscle as spontaneous SR Ca2+ release or Ca2+ sparks and, in some spiking tissues, as Ca2+ release that is triggered by the activation of sarcolemmal Ca2+ channels. Both processes display spatial localization in that release occurs at a higher frequency at specific subcellular regions. We have used two-photon flash photolysis (TPFP) of caged Ca2+ (DMNP-EDTA) in Fluo-4–loaded urinary bladder smooth muscle cells to determine the extent to which spatially localized increases in Ca2+ activate SR release and to further understand the molecular and biophysical processes underlying CICR. TPFP resulted in localized Ca2+ release in the form of Ca2+ sparks and Ca2+ waves that were distinguishable from increases in Ca2+ associated with Ca2+ uncaging, unequivocally demonstrating that Ca2+ release occurs subsequent to a localized rise in [Ca2+]i. TPFP-triggered Ca2+ release was not constrained to a few discharge regions but could be activated at all areas of the cell, with release usually occurring at or within several microns of the site of photolysis. As expected, the process of CICR was dominated by ryanodine receptor (RYR) activity, as ryanodine abolished individual Ca2+ sparks and evoked release with different threshold and kinetics in FKBP12.6-null cells. However, TPFP CICR was not completely inhibited by ryanodine; Ca2+ release with distinct kinetic features occurred with a higher TPFP threshold in the presence of ryanodine. This high threshold release was blocked by xestospongin C, and the pharmacological sensitivity and kinetics were consistent with CICR release at high local [Ca2+]i through inositol trisphosphate (InsP3) receptors (InsP3Rs). We conclude that CICR activated by localized Ca2+ release bears essential similarities to those observed by the activation of ICa (i.e., major dependence on the type 2 RYR), that the release is not spatially constrained to a few specific subcellular regions, and that Ca2+ release through InsP3R can occur at high local [Ca2+]i.
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Affiliation(s)
- Guangju Ji
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA
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18
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Farnum CE, Lenox M, Zipfel W, Horton W, Williams R. In vivo delivery of fluoresceinated dextrans to the murine growth plate: imaging of three vascular routes by multiphoton microscopy. ACTA ACUST UNITED AC 2006; 288:91-103. [PMID: 16342207 PMCID: PMC2573993 DOI: 10.1002/ar.a.20272] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Bone elongation by endochondral ossification occurs through the differentiation cascade of chondrocytes of cartilaginous growth plates. Molecules from the systemic vasculature reach the growth plate from three different directions: epiphyseal, metaphyseal, and a ring vessel and plexus associated with the perichondrium. This study is an analysis of the real-time dynamics of entrance of fluoresceinated tracers of different molecular weights into the growth plate from the systemic vasculature and tests the hypothesis that molecular weight is a key variable in the determination of both the directionality and the extent of tracer movement into the growth plate. Multiphoton microscopy was used for direct in vivo imaging of the murine proximal tibial growth plate in anesthetized 4- to 5-week-old transgenic mice with green fluorescent protein linked to the collagen II promoter. Mice were given an intracardiac injection of either fluorescein (332.3 Da) or fluoresceinated dextrans of 3, 10, 40, 70 kDa, singly or sequentially. For each tracer, directionality and rate of arrival, together with extent of movement within the growth plate, were imaged in real time. For small molecules (up to 10 kDa), vascular access from all three directions was observed and entrance was equally permissive from the metaphyseal and the epiphyseal sides. Within our detection limit (a few percent of vascular concentration), 40 kDa and larger dextrans did not enter. These results have implications both for understanding systemic and paracrine regulation of growth plate chondrocytic differentiation, as well as variables associated with effective drug delivery to growth plate chondrocytes.
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Affiliation(s)
- Cornelia E Farnum
- Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853, USA.
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Abstract
We study and demonstrate the technique of simultaneous spatial and temporal focusing of femtosecond pulses, with the aim to improve the signal-to-background ratio in multiphoton imaging. This concept is realized by spatially separating spectral components of pulses into a "rainbow beam" and recombining these components only at the spatial focus of the objective lens. Thus, temporal pulse width becomes a function of distance, with the shortest pulse width confined to the spatial focus. We developed analytical expressions to describe this method and experimentally demonstrated the feasibility. The concept of simultaneous spatial and temporal focusing of femtosecond pulses has the great potential to significantly reduce the background excitation in multiphoton microscopy, which fundamentally limits the imaging depth in highly scattering biological specimens.
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Atshaves BP, McIntosh AM, Lyuksyutova OI, Zipfel W, Webb WW, Schroeder F. Liver fatty acid-binding protein gene ablation inhibits branched-chain fatty acid metabolism in cultured primary hepatocytes. J Biol Chem 2004; 279:30954-65. [PMID: 15155724 DOI: 10.1074/jbc.m313571200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Whereas the role of liver fatty acid-binding protein (L-FABP) in the uptake, transport, mitochondrial oxidation, and esterification of normal straight-chain fatty acids has been studied extensively, almost nothing is known regarding the function of L-FABP in peroxisomal oxidation and metabolism of branched-chain fatty acids. Therefore, phytanic acid (most common dietary branched-chain fatty acid) was chosen to address these issues in cultured primary hepatocytes isolated from livers of L-FABP gene-ablated (-/-) and wild type (+/+) mice. These studies provided three new insights: First, L-FABP gene ablation reduced maximal, but not initial, uptake of phytanic acid 3.2-fold. Initial uptake of phytanic acid uptake was unaltered apparently due to concomitant 5.3-, 1.6-, and 1.4-fold up-regulation of plasma membrane fatty acid transporter/translocase proteins (glutamic-oxaloacetic transaminase, fatty acid transport protein, and fatty acid translocase, respectively). Second, L-FABP gene ablation inhibited phytanic acid peroxisomal oxidation and microsomal esterification. These effects were consistent with reduced cytoplasmic fatty acid transport as evidenced by multiphoton fluorescence photobleaching recovery, where L-FABP gene ablation reduced the cytoplasmic, but not membrane, diffusional component of NBD-stearic acid movement 2-fold. Third, lipid analysis of the L-FABP gene-ablated hepatocytes revealed an altered fatty acid phenotype. Free fatty acid and triglyceride levels were decreased 1.9- and 1.6-fold, respectively. In summary, results with cultured primary hepatocytes isolated from L-FABP (+/+) and L-FABP (-/-) mice demonstrated for the first time a physiological role of L-FABP in the uptake and metabolism of branched-chain fatty acids.
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Affiliation(s)
- Barbara P Atshaves
- Department of Physiology and Pharmacology, Texas A&M University, College Station, Texas 77843-4466, USA
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21
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Foquet M, Korlach J, Zipfel W, Webb WW, Craighead HG. DNA fragment sizing by single molecule detection in submicrometer-sized closed fluidic channels. Anal Chem 2002; 74:1415-22. [PMID: 11922312 DOI: 10.1021/ac011076w] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fabrication of fluidic channels with dimensions smaller than 1 microm is described and characterized in respect to their use for detection of individual DNA molecules. The sacrificial layer technique is used to fabricate these devices as it provides CMOS-compatible materials exhibiting low fluorescence background. It also allows creating microfluidics circuitry of submicrometer dimensions with great control. The small dimensions facilitate single molecule detection and minimize events of simultaneous passage of more than one molecule through the measurement volume. The behavior of DNA molecules inside these channels under an applied electrical field was first studied by fluorescence correlation spectroscopy using M13 double-stranded DNA. A linear relationship between the flow speed and applied electric field across the channel was observed. Speeds as high as 5 mm/s were reached, corresponding to only a few milliseconds of analysis time per molecule. The channels were then used to characterize a mixture of nine DNA fragments. Both the distribution and relative proportions of the individual fragments, as well as the overall concentration of the DNA sample, can be deduced from a single experiment. The amount of sample required for the analysis was approximately 10,000 molecules, or 76 fg. Other potential applications of these submicrometer structures for DNA analysis are discussed.
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Affiliation(s)
- Mathieu Foquet
- School of Applied & Engineering Physics, Cornell University, Ithaca, New York 14853, USA
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Bago B, Zipfel W, Williams RM, Jun J, Arreola R, Lammers PJ, Pfeffer PE, Shachar-Hill Y. Translocation and utilization of fungal storage lipid in the arbuscular mycorrhizal symbiosis. Plant Physiol 2002; 128:108-124. [PMID: 11788757 DOI: 10.1104/pp.010466] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Carbon is transferred from the plant to the fungus as hexose, but the main form of carbon stored by the mycobiont at all stages of its life cycle is triacylglycerol. Previous isotopic labeling experiments showed that the fungus exports this storage lipid from the intraradical mycelium (IRM) to the extraradical mycelium (ERM). Here, in vivo multiphoton microscopy was used to observe the movement of lipid bodies through the fungal colony and to determine their sizes, distribution, and velocities. The distribution of lipid bodies along fungal hyphae suggests that they are progressively consumed as they move toward growing tips. We report the isolation and measurements of expression of an AM fungal expressed sequence tag that encodes a putative acyl-coenzyme A dehydrogenase; its deduced amino acid sequence suggests that it may function in the anabolic flux of carbon from lipid to carbohydrate. Time-lapse image sequences show lipid bodies moving in both directions along hyphae and nuclear magnetic resonance analysis of labeling patterns after supplying 13C-labeled glycerol to either extraradical hyphae or colonized roots shows that there is indeed significant bidirectional translocation between IRM and ERM. We conclude that large amounts of lipid are translocated within the AM fungal colony and that, whereas net movement is from the IRM to the ERM, there is also substantial recirculation throughout the fungus.
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Affiliation(s)
- Berta Bago
- Departmento de Microbiología del Suelo y Systema Simbióticos, Estación Experimental del Zaidín, calle Profesor Albareda 1, 18008-Granada, Spain.
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Bago B, Zipfel W, Williams RM, Jun J, Arreola R, Lammers PJ, Pfeffer PE, Shachar-Hill Y. Translocation and utilization of fungal storage lipid in the arbuscular mycorrhizal symbiosis. Plant Physiol 2002; 128:108-24. [PMID: 11788757 PMCID: PMC148950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/24/2001] [Accepted: 09/27/2001] [Indexed: 04/17/2023]
Abstract
The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Carbon is transferred from the plant to the fungus as hexose, but the main form of carbon stored by the mycobiont at all stages of its life cycle is triacylglycerol. Previous isotopic labeling experiments showed that the fungus exports this storage lipid from the intraradical mycelium (IRM) to the extraradical mycelium (ERM). Here, in vivo multiphoton microscopy was used to observe the movement of lipid bodies through the fungal colony and to determine their sizes, distribution, and velocities. The distribution of lipid bodies along fungal hyphae suggests that they are progressively consumed as they move toward growing tips. We report the isolation and measurements of expression of an AM fungal expressed sequence tag that encodes a putative acyl-coenzyme A dehydrogenase; its deduced amino acid sequence suggests that it may function in the anabolic flux of carbon from lipid to carbohydrate. Time-lapse image sequences show lipid bodies moving in both directions along hyphae and nuclear magnetic resonance analysis of labeling patterns after supplying 13C-labeled glycerol to either extraradical hyphae or colonized roots shows that there is indeed significant bidirectional translocation between IRM and ERM. We conclude that large amounts of lipid are translocated within the AM fungal colony and that, whereas net movement is from the IRM to the ERM, there is also substantial recirculation throughout the fungus.
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Affiliation(s)
- Berta Bago
- Departmento de Microbiología del Suelo y Systema Simbióticos, Estación Experimental del Zaidín, calle Profesor Albareda 1, 18008-Granada, Spain.
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Abstract
Multiphoton fluorescence photobleaching recovery (MP-FPR) is a technique for measuring the three-dimensional (3D) mobility of fluorescent molecules with 3D spatial resolution of a few microns. A brief, intense flash of mode-locked laser light pulses excites fluorescent molecules via multiphoton excitation in an ellipsoidal focal volume and photobleaches a fraction. Because multiphoton excitation of fluorophores is intrinsically confined to the high-intensity focal volume of the illuminating beam, the bleached region is restricted to a known, three-dimensionally defined volume. Fluorescence in this focal volume is measured with multiphoton excitation, using the attenuated laser beam to measure fluorescence recovery as fresh unbleached dye diffuses in. The time course of the fluorescence recovery signal after photobleaching can be analyzed to determine the diffusion coefficient of the fluorescent species. The mathematical formulas used to fit MP-FPR recovery curves and the techniques needed to properly utilize them to acquire the diffusion coefficients of fluorescently labeled molecules within cells are presented here. MP-FPR is demonstrated on calcein in RBL-2H3 cells, using an anomalous subdiffusion model, as well as in aqueous solutions of wild-type green fluorescent protein, yielding a diffusion coefficient of 8.7 x 10(-7) cm(2)s(-1) in excellent agreement with the results of other techniques.
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Affiliation(s)
- E B Brown
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
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Caylor CL, Dobrianov I, Lemay SG, Kimmer C, Kriminski S, Finkelstein KD, Zipfel W, Webb WW, Thomas BR, Chernov AA, Thorne RE. Macromolecular impurities and disorder in protein crystals. Proteins 1999; 36:270-281. [PMID: 10409821 DOI: 10.1002/(sici)1097-0134(19990815)36:3<270::aid-prot2"3.0.co;2-n] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The mechanisms by which macromolecular impurities degrade the diffraction properties of protein crystals have been investigated using X-ray topography, high-resolution diffraction line shape measurements, crystallographic data collection, chemical analysis, and two-photon excitation fluorescence microscopy. Hen egg-white lysozyme crystals grown from solutions containing a structurally unrelated protein (ovotransferrin) and a related protein (turkey egg-white lysozyme) can exhibit significantly broadened mosaicity due to formation of cracks and dislocations but have overall B factors and diffraction resolutions comparable to those of crystals grown from uncontaminated lysozyme. Direct fluorescence imaging of the three-dimensional impurity distribution shows that impurities incorporate with different densities in sectors formed by growth on different crystal faces, and that impurity densities in the crystal core and along boundaries between growth sectors can be much larger than in other parts of the crystal. These nonuniformities create stresses that drive formation of the defects responsible for the mosaic broadening. Our results provide a rationale for the use of seeding to obtain high-quality crystals from heavily contaminated solutions and have implications for the use of crystallization for protein purification. Proteins 1999;36:270-281.
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Affiliation(s)
- C L Caylor
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
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Caylor C, Dobrianov I, Lemay S, Kimmer C, Kriminski S, Finkelstein K, Zipfel W, Webb W, Thomas B, Chernov A, Thorne R. Macromolecular impurities and disorder in protein crystals. Proteins 1999. [DOI: 10.1002/(sici)1097-0134(19990815)36:3<270::aid-prot2>3.0.co;2-n] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Bago B, Zipfel W, Williams RM, Piché Y. Nuclei of symbiotic arbuscular mycorrhizal fungi as revealed by in vivo two-photon microscopy. Protoplasma 1999; 209:77-89. [PMID: 18987796 DOI: 10.1007/bf01415703] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/1998] [Accepted: 03/16/1999] [Indexed: 05/27/2023]
Abstract
The present work reports the results obtained from in vivo studies on the distribution and behavior of nuclei of two arbuscular mycorrhizal (AM) fungi growing in symbiosis with tomato root organ cultures (AM monoxenic cultures). Upon staining with 4',6-diamidino-2-phenylindole and two-photon microscopy (2PM) observations, symbiotic thick runner hyphae appeared mostly opaque to 2PM and did not reveal nuclei within them; thin runner hyphae showed dimly stained nuclei along them, whereas nuclei were clearly visible within the branches of the so-called branched absorbing structures. When visible, nuclei appeared anchored laterally at regular intervals along the symbiotic AM extraradical hyphae. Other nuclei migrate through the hyphal central core; this migration occurs in pulses. Simultaneous observations on different areas of extraradical AM mycelium revealed the existence of lysed compartments along the fungal hyphae, containing nuclei remnants and/or chromatin masses. All these results give new insights in (i) the differential permeability of AM hyphae in the symbiotic versus the asymbiotic state; (ii) the behavior and distribution of nuclei along the symbiotic extraradical mycelium; (iii) the occurrence of ageing events within the AM fungal colony; and (iv) the existence of "healing" mechanisms aiming to restrict the damage induced by such ageing or lytic events. An AM fungal strategy for hyphal survival under adverse conditions is also suggested.
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Affiliation(s)
- B Bago
- Centre de Recherche en Biologie Forestière, Université Laval, Ste-Foy, Québec, Canada.
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Xu C, Zipfel W, Shear JB, Williams RM, Webb WW. Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy. Proc Natl Acad Sci U S A 1996; 93:10763-8. [PMID: 8855254 PMCID: PMC38229 DOI: 10.1073/pnas.93.20.10763] [Citation(s) in RCA: 705] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Intrinsic, three-dimensionally resolved, microscopic imaging of dynamical structures and biochemical processes in living preparations has been realized by nonlinear laser scanning fluorescence microscopy. The search for useful two-photon and three-photon excitation spectra, motivated by the emergence of nonlinear microscopy as a powerful biophysical instrument, has now discovered a virtual artist's palette of chemical indicators, fluorescent markers, and native biological fluorophores, including NADH, flavins, and green fluorescent proteins, that are applicable to living biological preparations. More than 25 two-photon excitation spectra of ultraviolet and visible absorbing molecules reveal useful cross sections, some conveniently blue-shifted, for near-infrared absorption. Measurements of three-photon fluorophore excitation spectra now define alternative windows at relatively benign wavelengths to excite deeper ultraviolet fluorophores. The inherent optical sectioning capability of nonlinear excitation provides three-dimensional resolution for imaging and avoids out-of-focus background and photodamage. Here, the measured nonlinear excitation spectra and their photophysical characteristics that empower nonlinear laser microscopy for biological imaging are described.
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Affiliation(s)
- C Xu
- Cornell University, Ithaca, NY 14853, USA
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Abstract
We present computer simulations of excited state dynamics in models of PS I and PS II which are based upon known structural and spectral properties of the antennae. In particular, these models constrain the pigment binding sites to three-dimensional volumes determined from molecular properties of the antenna complexes. The simulations demonstrate that within a 10-30 ps after light absorption, rapid energy transfer among coupled antenna chlorophylls leads to a quasiequilibrium state in which the fraction of the excited state on any antenna chlorophyll, normalized to the total excited state remaining on the model, remains constant with time. We describe this quasiequilibrium state as a "transfer equilibrium" (TE) state because of its dependence on the rates of processes that couple excited state motion and quenching in the antenna as well as on the individual antenna site energies and temperature. The TE state is not a true equilibrium in that loss of the excited state primarily due to photochemistry (but also due to fluorescence, thermal emission, and intersystem crossing) continues once TE is established. Depending on the dynamics of the system, the normalized distribution of excited state at TE may differ substantially from the Boltzmann distribution (the state of the model at infinite time in the absence of any avenues for decay of excited state). The models predict lifetimes, equilibration times, and photochemical yields that are in agreement with experimental data and affirm trap-limited dynamics in both photosystems. The rapid occurrence of TE states implies that any excited state dynamics that depends on antenna structure and excitation wavelength must occur before the TE state is established. We demonstrate that the excited state distribution of the TE state is central to determining the excited state lifetime and quantum efficiency of photochemistry.
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Affiliation(s)
- P D Laible
- Section of Plant Biology, Cornell University, Ithaca, New York 14853-5908
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Zipfel W, Hewicker-Trautwein M, Trautwein G. Demonstration of immunoglobulins and complement in canine and feline autoimmune and non-autoimmune skin diseases with the direct immunofluorescence and indirect immunoperoxidase method. Zentralbl Veterinarmed A 1992; 39:494-501. [PMID: 1455915 DOI: 10.1111/j.1439-0442.1992.tb00208.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Skin sections from 71 dogs and 10 cats with bullous autoimmune skin diseases and various non-autoimmune dermatopathies were studied for the presence of immunoglobulins (canine IgG, IgM, IgA; feline IgG) and complement (canine C3) using the direct immunofluorescence method (DIF) and the indirect immunoperoxidase method (IIP). In cases of autoimmune skin diseases (9 dogs, 3 cats) both methods were of comparable sensitivity for the detection of epidermal deposits. In canine cases with non-autoimmune dermatopathies, epidermal immunoreactivity was found in 16.1% of cases with the DIF method, and in 29.0% of cases with the IIP method. With both methods, epidermal deposits were most frequently seen in skin sections of dogs with bacterial diseases. Furthermore, positive reactions were found in canine cases with hypersensitivity disorders, endocrine dermatosis, dermatomycosis, parasitic disease, cutaneous Leishmaniasis and in cases with non-specific dermatopathies of uncertain aetiology. In the majority of canine cases intercellular deposits of IgG were found. Immunohistological results should always be interpreted in conjunction with clinical and histomorphological findings in order to establish a diagnosis of autoimmune skin disease and to prevent misdiagnoses.
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Affiliation(s)
- W Zipfel
- Department of Pathology, School of Veterinary Medicine, Hannover, Federal Republic of Germany
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Zipfel W, Owens TG. Calculation of absolute photosystem I absorption cross-sections from P700 photo-oxidation kinetics. Photosynth Res 1991; 29:23-35. [PMID: 24415037 DOI: 10.1007/bf00035203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/1991] [Accepted: 05/24/1991] [Indexed: 06/03/2023]
Abstract
A procedure is described which permits determination of the absolute absorption cross-section of a photosynthetic unit from the kinetics of reaction center photo-oxidation under weak, continuous actinic illumination. The method was first tested on a simple model compound of known absorption cross-section. We then applied the technique to absorption cross-section and functional antenna size measurements in photosystem I (PS I). A kinetic model is presented that can be used to fit P700 photo-oxidation measurements and extract the effective photochemical rate constant. The procedure is shown to properly correct for sample scattering and for the presence of heterogeneous absorbers (pigments not functionally coupled to P700). The relevance of these corrections to comparisons of antenna size using techniques that measure 'relative' absorption cross-sections is discussed. Measurements on pea thylakoids in the presence and absence of 5 mM MgCl2 show a 45% increase in PS I absorption cross-section in unstacked thylakoids. Analysis of detergent-isolated 'native' PS I preparations (200 chlorophyll a+b/P700) clearly indicate that the preparation contains a broad distribution of antenna sizes. Finally, we confirm that Chlamydomonas reinhardtii strain LM3-A4d contains a PS I core antenna complex which binds only ∼60 chlorophyll a/P700, about half the functional size of the wild type complex. Limitations associated with calculation of functional antenna size from cross-section measurements are also discussed.
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Affiliation(s)
- W Zipfel
- Section of Plant Biology, Cornell University, 14853-5908, Ithaca, NY, USA
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Hewicker M, Beardi B, Zipfel W, Opitz M, Trautwein G. [Epidermotropic lymphosarcoma (mycosis fungoides) in a dog]. Tierarztl Prax 1990; 18:633-9. [PMID: 2080509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The clinical findings in a 16-year-old dog with mycosis fungoides are described. The definitive diagnosis was based on the characteristic histopathological lesions in the skin and mucosal biopsies. An immunohistological examination using monoclonal antibodies directed against the Thy-1 antigen of canine peripheral T lymphocytes did not give any further evidence of the identity of the infiltrating lymphoid cells.
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Affiliation(s)
- M Hewicker
- Institut für Pathologie, Tierärztlichen Hochschule Hannover
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Zipfel W. [Drugs and foods. Attempt at differentiation]. Med Klin 1968; 63:1604-6. [PMID: 5720556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Zipfel W. [Health protection in the correct nourishment]. Med Klin 1966; 61:516-8. [PMID: 5995173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Zipfel W. Rechtsprechung. Eur Food Res Technol 1962. [DOI: 10.1007/bf01884898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zipfel W. Rechtsprechung. Eur Food Res Technol 1961. [DOI: 10.1007/bf01577077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zipfel W. Rechtsprechung. Eur Food Res Technol 1958. [DOI: 10.1007/bf01744794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zipfel W. Rechtsprechung. Eur Food Res Technol 1958. [DOI: 10.1007/bf01787505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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