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Brister EY, Vasi Z, Antipova O, Robinson A, Tan X, Agarwal A, Stock SR, Carriero A, Richter CP. X-ray fluorescence microscopy: A method of measuring ion concentrations in the ear. Hear Res 2020; 391:107948. [PMID: 32283439 DOI: 10.1016/j.heares.2020.107948] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/18/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022]
Abstract
This technical note describes synchrotron x-ray fluorescence microscopy (XFM) as a method for measuring the concentrations of different elements in cross-sections of the ear at extremely high resolution. This method could be of great importance for addressing many open questions in hearing research. XFM uses synchrotron radiation to evoke emissions from many biologically relevant elements in the tissue. The intensity and wavelength of the emitted radiation provide a fingerprint of the tissue composition that can be used to measure the concentration of the elements in the sampled location. Here, we focus on energies that target biologically-relevant elements of the periodic table between magnesium and zinc. Since a highly focused x-ray beam is used, the spot size is well below 1 μm and the samples can be scanned at a nanometer lateral resolution. This study shows that measurement of the concentrations of different elements is possible in a mid-modiolar cross-section of a mouse cochlea. Images are presented that indicate potassium and chloride "hot spots" in the spiral ligament and the spiral limbus, providing experimental evidence for the potassium recycling pathway and showing the cochlear structures involved. Scans of a section obtained from the incus, one of the middle ear ossicles, in a developing mouse have shown that zinc is not uniformly distributed This supports the hypothesis that zinc plays a special role in the process of ossification. Although limited by sophisticated sample preparation and sectioning, the method provides ample exciting opportunities, to understand the role of genetics and epigenetics on hearing mechanisms in ontogeny and phylogeny.
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Affiliation(s)
- Eileen Y Brister
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States; Department of Speech and Hearing Sciences, Indiana University, Bloomington, IN, United States
| | - Zahra Vasi
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States; Illinois Mathematics and Science Academy, Aurora, IL, United States
| | - Olga Antipova
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, United States
| | - Alan Robinson
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Xiaodong Tan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Aditi Agarwal
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Stuart R Stock
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Alessandra Carriero
- Department of Biomedical Engineering, The City College of New York, NY, United States
| | - Claus-Peter Richter
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States; Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States; The Hugh Knowles Center, Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, United States.
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Ding D, McFadden SL, Woo JM, Salvi RJ. Ethacrynic acid rapidly and selectively abolishes blood flow in vessels supplying the lateral wall of the cochlea. Hear Res 2002; 173:1-9. [PMID: 12372630 DOI: 10.1016/s0378-5955(02)00585-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mechanisms underlying the ototoxicity of ethacrynic acid (EA) are not fully understood. Previous studies have focused on morphologic and enzymatic changes in the stria vascularis. The current experiment shows that one of the earliest effects of EA is ischemia, resulting from impaired blood flow in vessels supplying the lateral wall of the cochlea. Inner ear microcirculation, endocochlear potentials, compound action potentials (CAP), cochlear microphonics (CM) and summating potentials (SP) were monitored over time in chinchillas following a single injection of EA (40 mg/kg i.v.). At all times after EA injection, blood vessels supplying the spiral lamina, modiolus, and vestibular end organs appeared normal. In contrast, lateral wall (spiral ligament and stria vascularis) vessels were poorly stained with eosin 2 min after EA injection, and devoid of red blood cells at 30 min post EA. Decline, but not recovery, of CAP, CM and SP followed the microcirculation changes in the lateral wall. Reperfusion was delayed in stria vascularis arterioles relative to other lateral wall vessels. The ischemia-reperfusion caused by EA would be expected to generate large quantities of free radicals, which may trigger or contribute to the cellular, enzymatic, and functional pathologies that have been described in detail previously.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, 215 Parker Hall, University at Buffalo, NY 14214, USA
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Adamson CL, Davis RL. Differentiation of cyst-forming stria vascularis tissues in vitro. Hear Res 1999; 129:111-27. [PMID: 10190757 DOI: 10.1016/s0378-5955(98)00225-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The marginal cells of the stria vascularis possess distinctive morphological characteristics associated with their role in endolymph production. Interestingly, when stria-derived epithelial cells are grown in association with the underlying mesenchyme, the final differentiation of these cell types does not occur. Beyond the rudimentary polarity that is established, similar to that shown in epithelial monolayers, cells in culture bear only a slight resemblance to their marginal cell counterparts in vivo. The ultrastructural features that typify these epithelia, extensive cytoplasmic invaginations, with an abundance of mitochondria, and darkly stained cytoplasm, are not evident under standard culture conditions. In order to determine whether fluid transport, a key function of the stria vascularis, has an effect on the ultrastructural morphology, we examined de novo stria vascularis tissues that formed a fluid-filled cyst in vitro. We found that only cells associated with the luminal structure demonstrated dark cytoplasmic staining and amplification of the basolateral membrane of the marginal cells. Additionally, other epithelial features, such as mitochondria-rich and microvilli-rich cells, were observed in cyst-forming tissues. The enhancement of the marginal cell specializations was not as robust as that observed in vivo; however, they were clearly more extensive when compared to cells in the same culture that were not associated with a fluid-filled lumen. Thus it appears that fluid transport may be necessary to maximize differentiation of stria vascularis tissues in vitro.
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Affiliation(s)
- C L Adamson
- Rutgers University, Department of Cell Biology and Neuroscience, Piscataway, NJ 08854-8082, USA.
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Duvall AJ, Robinson KS. Effects on cochlear morphology of repeated insults to the stria vascularis. Ann Otol Rhinol Laryngol 1991; 100:572-6. [PMID: 2064270 DOI: 10.1177/000348949110000710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The interrelationship of stria vascularis and organ of Corti integrity was investigated. Strial morphology was altered by repeated injections of ethacrynic acid in the chinchilla. Although prolonged temporary strial damage was created, neither strial atrophy nor organ of Corti damage resulted.
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Affiliation(s)
- A J Duvall
- Department of Otolaryngology, Medical School, University of Minnesota, Minneapolis 55455
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Ikeda K, Morizono T. Electrochemical profiles for monovalent ions in the stria vascularis: cellular model of ion transport mechanisms. Hear Res 1989; 39:279-86. [PMID: 2753832 DOI: 10.1016/0378-5955(89)90047-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The electrochemical profiles for K+, Na+, and Cl- ions in tissues of the lateral wall of the cochlea in the chinchilla were measured using an ion-selective microelectrode. Based upon the changes of the d.c. resting potential and ion composition, five distinct compartments were identified in the lateral wall. The first compartment, corresponding to the spiral ligament, showed an ionic composition similar to perilymph. The second, corresponding to the basal cell layer of the stria vascularis, showed a characteristic recording of the ion-sensitive barrel: a spike-like change of the ion concentration (K+: 100.1 +/- 16.8 mM, Na+: 33.9 +/- 20.2 mM, Cl-: 70.2 +/- 9.4 mM). The third compartment, corresponding to the extracellular space of the stria vascularis, showed a higher d.c. potential (60.4 +/- 9.5 mV) than that of the second region, with a low K+ concentration (22.1 +/- 14.9 mM) and a high Na+ (78.3 +/- 5.7 mV) than the fifth compartment, corresponding to the scala media (78.1 +/- 4.1 mV), and K+ and Na+ concentrations similar to those of endolymph, while the Cl- concentration in the fourth compartment (117.6 +/- 21.5 mM) was lower than that of endolymph (143.3 +/- 13.9 mM). A thermodynamic study of electrochemical potential gradients suggests the possibility that the Na-K pump and Na-K-2Cl cotransport exist at the basolateral membrane of the marginal cells.
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Affiliation(s)
- K Ikeda
- Department of Otolaryngology, University of Minnesota Medical School, Minneapolis
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