| 1. |
- Bruder, CEG, et al.
(författare)
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High resolution deletion analysis of constitutional DNA from neurofibromatosis type 2 (NF2) patients using microarray-CGH
- 2001
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Ingår i: Human Molecular Genetics. - Oxford, United Kingdom : Oxford University Press. - 0964-6906 .- 1460-2083. ; 1, s. 271-
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Tidskriftsartikel (refereegranskat)abstract
- Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder whose hallmark is bilateral vestibular schwannoma. It displays a pronounced clinical heterogeneity with mild to severe forms. The NF2 tumor suppressor (merlin/schwannomin) has been cloned and extensively analyzed for mutations in patients with different clinical variants of the disease. Correlation between the type of the NF2 gene mutation and the patient phenotype has been suggested to exist. However, several independent studies have shown that a fraction of NF2 patients with various phenotypes have constitutional deletions that partly or entirely remove one copy of the NF2 gene. The purpose of this study was to examine a 7 Mb interval in the vicinity of the NF2 gene in a large series of NF2 patients in order to determine the frequency and extent of deletions. A total of 116 NF2 patients were analyzed using high-resolution array-comparative genomic hybridization (CGH) on an array covering at least 90% of this region of 22q around the NF2 locus. Deletions, which remove one copy of the entire gene or are predicted to truncate the schwannomin protein, were detected in 8 severe, 10 moderate and 6 mild patients. This result does not support the correlation between the type of mutation affecting the NF2 gene and the disease phenotype. This work also demonstrates the general usefulness of the array-CON methodology for rapid and comprehensive detection of small (down to 40 kb) heterozygous and/or homozygous deletions occurring in constitutional or tumor-derived DNA.
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| 2. |
- Eckhard, A, et al.
(författare)
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Regulation of the perilymphatic-endolymphatic water shunt in the cochlea by membrane translocation of aquaporin-5
- 2015
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Ingår i: Pflügers Archiv. - : Springer Science and Business Media LLC. - 0031-6768 .- 1432-2013. ; 467:12, s. 2571-2588
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Tidskriftsartikel (refereegranskat)abstract
- Volume homeostasis of the cochlear endolymph depends on radial and longitudinal endolymph movements (LEMs). LEMs measured in vivo have been exclusively recognized under physiologically challenging conditions, such as experimentally induced alterations of perilymph osmolarity or endolymph volume. The regulatory mechanisms that adjust LEMs to the physiological requirements of endolymph volume homeostasis remain unknown. Here, we describe the formation of an aquaporin (AQP)-based "water shunt" during the postnatal development of the mouse cochlea and its regulation by different triggers. The final complementary expression pattern of AQP5 (apical membrane) and AQP4 (basolateral membrane) in outer sulcus cells (OSCs) of the cochlear apex is acquired at the onset of hearing function (postnatal day (p)8-p12). In vitro, hyperosmolar perfusion of the perilymphatic fluid spaces or the administration of the muscarinic agonist pilocarpine in cochlear explants (p14) induced the translocation of AQP5 channel proteins into the apical membranes of OSCs. AQP5 membrane translocation was blocked by the muscarinic antagonist atropine. The muscarinic M3 acetylcholine (ACh) receptor (M3R) was identified in murine OSCs via mRNA expression, immunolabeling, and in vitro binding studies using an M3R-specific fluorescent ligand. Finally, the water shunt elements AQP4, AQP5, and M3R were also demonstrated in OSCs of the human cochlea. The regulation of the AQP4/AQP5 water shunt in OSCs of the cochlear apex provides a molecular basis for regulated endolymphatic volume homeostasis. Moreover, its dysregulation or disruption may have pathophysiologic implications for clinical conditions related to endolymphatic hydrops, such as Ménière's disease.
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| 3. |
- Egana, I, et al.
(författare)
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Female mice lacking Pald1 exhibit endothelial cell apoptosis and emphysema
- 2017
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1, s. 15453-
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Tidskriftsartikel (refereegranskat)abstract
- Paladin (Pald1, mKIAA1274 or x99384) was identified in screens for vascular-specific genes and is a putative phosphatase. Paladin has also been proposed to be involved in various biological processes such as insulin signaling, innate immunity and neural crest migration. To determine the role of paladin we have now characterized the Pald1 knock-out mouse in a broad array of behavioral, physiological and biochemical tests. Here, we show that female, but not male, Pald1 heterozygous and homozygous knock-out mice display an emphysema-like histology with increased alveolar air spaces and impaired lung function with an obstructive phenotype. In contrast to many other tissues where Pald1 is restricted to the vascular compartment, Pald1 is expressed in both the epithelial and mesenchymal compartments of the postnatal lung. However, in Pald1 knock-out females, there is a specific increase in apoptosis and proliferation of endothelial cells, but not in non-endothelial cells. This results in a transient reduction of endothelial cells in the maturing lung. Our data suggests that Pald1 is required during lung vascular development and for normal function of the developing and adult lung in a sex-specific manner. To our knowledge, this is the first report of a sex-specific effect on endothelial cell apoptosis.
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| 4. |
- Henson, M.M., et al.
(författare)
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Smooth muscle in the annulus fibrosus of the tympanic membrane in bats, rodents, insectivores and humans
- 2005
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Ingår i: Hearing Research. - : Elsevier BV. - 0378-5955 .- 1878-5891. ; 200:1-2, s. 29-37
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Tidskriftsartikel (refereegranskat)abstract
- The annulus fibrosus and its attachment to the bony tympanic ring were studied in a series of mammals. In the pallid bat, Antrozous pallidus, there is an extensive plexus of large interconnected blood sinuses in the part of the annulus that borders the tympanic bone. The spaces between the sinuses are packed with smooth muscle cells. Most of the cells have a predominately radial orientation; they extend from the bony tympanic sulcus to a dense collagenous matrix (apical zone) where radially oriented fibers of the pars tensa are confluent with the annulus. The muscles and vessels constitute a myovascular zone. A structurally similar myovascular zone is also present in the European hedgehog. In rodents, the annulus lacks the large interconnected blood sinuses but many small vessels are present. Smooth muscle is concentrated in the broad area of attachment of the annulus to the tympanic bone. In the gerbil, smooth muscle seems to be concentrated in the central part of the width of the annulus where it is attached to bone and radiates toward the tympanic membrane. In humans collections of radially oriented smooth muscle cells were found in several locations. The smooth muscle in all species studied appears to form a rim of contractile elements for the pars tensa. This arrangement suggests a role in controlling blood flow and/or creating and maintaining tension on the tympanic membrane.
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| 5. |
- Li, Hao, 1984-, et al.
(författare)
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Unlocking the human inner ear for therapeutic intervention
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The human inner ear contains minute three-dimensional neurosensory structures that are deeply embedded within the skull base, rendering them relatively inaccessible to regenerative therapies for hearing loss. Here we provide a detailed characterisation of the functional architecture of the space that hosts the cell bodies of the auditory nerve to make them safely accessible for the first time for therapeutic intervention. We used synchrotron phase-contrast imaging which offers the required microscopic soft-tissue contrast definition while simultaneously displaying precise bony anatomic detail. Using volume-rendering software we constructed highly accurate 3-dimensional representations of the inner ear. The cell bodies are arranged in a bony helical canal that spirals from the base of the cochlea to its apex; the canal volume is 1.6 mu L but with a diffusion potential of 15 mu L. Modelling data from 10 temporal bones enabled definition of a safe trajectory for therapeutic access while preserving the cochlea's internal architecture. We validated the approach through surgical simulation, anatomical dissection and micro-radiographic analysis. These findings will facilitate future clinical trials of novel therapeutic interventions to restore hearing.
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| 6. |
- Agrawal, Sumit, et al.
(författare)
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The secondary spiral lamina and its relevance in cochlear implant surgery
- 2018
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Ingår i: Upsala Journal of Medical Sciences. - : TAYLOR & FRANCIS LTD. - 0300-9734 .- 2000-1967. ; 123:1, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We used synchrotron radiation phase contrast imaging (SR-PCI) to study the 3D microanatomy of the basilar membrane (BM) and its attachment to the spiral ligament (SL) (with a conceivable secondary spiral lamina [SSL] or secondary spiral plate) at the round window membrane (RWM) in the human cochlea. The conception of this complex anatomy may be essential for accomplishing structural preservation at cochlear implant surgery.Material and methods: Sixteen freshly fixed human temporal bones were used to reproduce the BM, SL, primary and secondary osseous spiral laminae (OSL), and RWM using volume-rendering software. Confocal microscopy immunohistochemistry (IHC) was performed to analyze the molecular constituents.Results: SR-PCI reproduced the soft tissues including the RWM, Reissner's membrane (RM), and the BM attachment to the lateral wall (LW) in three dimensions. A variable SR-PCI contrast enhancement was recognized in the caudal part of the SL facing the scala tympani (ST). It seemed to represent a SSL allied to the basilar crest (BC). The SSL extended along the postero-superior margin of the round window (RW) and immunohistochemically expressed type II collagen.Conclusions: Unlike in several mammalian species, the human SSL is restricted to the most basal portion of the cochlea around the RW. It anchors the BM and may influence its hydro-mechanical properties. It could also help to shield the BM from the RW. The microanatomy should be considered at cochlear implant surgery.
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| 7. |
- Chacko, L. Johnson, et al.
(författare)
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Role of BDNF and neurotrophic receptors in human inner ear development
- 2017
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Ingår i: Cell and Tissue Research. - : SPRINGER. - 0302-766X .- 1432-0878. ; 370:3, s. 347-363
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Tidskriftsartikel (refereegranskat)abstract
- The expression patterns of the neurotrophin, brain-derived neurotrophic factor, BDNF, and the neurotrophic receptors-p75NTR and Trk receptors-in the developing human fetal inner ear between the gestational weeks (GW) 9 to 12 are examined via in situ hybridization and immunohistochemistry. BDNF mRNA expression was highest in the cochlea at GW 9 but declined in the course of development. In contrast to embryonic murine specimens, a decline in BDNF expression from the apical to the basal turn of the cochlea could not be observed. p75NTR immunostaining was most prominent in the nerve fibers that penetrate into the sensory epithelia of the cochlea, the urticule and the saccule as gestational age progresses. TrkB and TrkC expression intensified towards GW 12, at which point the BDNF mRNA localization was at its lowest. TrkA expression was limited to fiber subpopulations of the facial nerve at GW 10. In the adult human inner ear, we observed BDNF mRNA expression in the apical poles of the cochlear hair cells and supporting cells, while in the adult human utricle, the expression was localized in the vestibular hair cells. We demonstrate the highly specific staining patterns of BDNF mRNA and its putative receptors over a developmental period in which multiple hearing disorders are manifested. Our findings suggest that BDNF and neurotrophin receptors are important players during early human inner ear development. In particular, they seem to be important for the survival of the afferent sensory neurons.
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| 8. |
- Eckhard, A, et al.
(författare)
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Water permeability of the mammalian cochlea : functional features of an aquaporin-facilitated water shunt at the perilymph-endolymph barrier
- 2014
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Ingår i: Pflügers Archiv. - : Springer Science and Business Media LLC. - 0031-6768 .- 1432-2013. ; 466:10, s. 1963-1985
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Tidskriftsartikel (refereegranskat)abstract
- The cochlear duct epithelium (CDE) constitutes a tight barrier that effectively separates the inner ear fluids, endolymph and perilymph, thereby maintaining distinct ionic and osmotic gradients that are essential for auditory function. However, in vivo experiments have demonstrated that the CDE allows for rapid water exchange between fluid compartments. The molecular mechanism governing water permeation across the CDE remains elusive. We computationally determined the diffusional (P D) and osmotic (P f) water permeability coefficients for the mammalian CDE based on in silico simulations of cochlear water dynamics integrating previously derived in vivo experimental data on fluid flow with expression sites of molecular water channels (aquaporins, AQPs). The P D of the entire CDE (P D = 8.18 × 10(-5) cm s(-1)) and its individual partitions including Reissner's membrane (P D = 12.06 × 10(-5) cm s(-1)) and the organ of Corti (P D = 10.2 × 10(-5) cm s(-1)) were similar to other epithelia with AQP-facilitated water permeation. The P f of the CDE (P f = 6.15 × 10(-4) cm s(-1)) was also in the range of other epithelia while an exceptionally high P f was determined for an epithelial subdomain of outer sulcus cells in the cochlear apex co-expressing AQP4 and AQP5 (OSCs; P f = 156.90 × 10(-3) cm s(-1)). The P f/P D ratios of the CDE (P f/P D = 7.52) and OSCs (P f/P D = 242.02) indicate an aqueous pore-facilitated water exchange and reveal a high-transfer region or "water shunt" in the cochlear apex. This "water shunt" explains experimentally determined phenomena of endolymphatic longitudinal flow towards the cochlear apex. The water permeability coefficients of the CDE emphasise the physiological and pathophysiological relevance of water dynamics in the cochlea in particular for endolymphatic hydrops and Ménière's disease.
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| 9. |
- Enghag, Sara, et al.
(författare)
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Incus Necrosis and Blood Supply : A Micro-CT and Synchrotron Imaging Study
- 2019
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Ingår i: Otology and Neurotology. - : LIPPINCOTT WILLIAMS & WILKINS. - 1531-7129 .- 1537-4505. ; 40:7, s. E713-E722
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Tidskriftsartikel (refereegranskat)abstract
- Background: Incus necrosis is a common complication following stapes surgery and is associated with impaired microcirculation. The objective of this study was to investigate the vascular anatomy of the human incus by using light microscopy, micro-computed tomography (micro-CT), and synchrotron phase-contrast imaging (SR-PCI) for a novel three-dimensional (3D) analysis of the middle ear, mucosal folds, major vascular pathways, and intraosseous vascular bone channels. Methods: One-hundred-and-fifty temporal bones from the Uppsala collection were analyzed under light microscopy. Twenty temporal bones underwent high-resolution micro-CT scanning, and an additional seven specimens underwent SR-PCI at the Canadian Lightsource in Saskatoon, Canada. One of these specimens was from an individual who had undergone stapes surgery. Data were processed with volume-rendering software to create 3D reconstructions using scalar opacity mapping for bone transparency, cropping, and soft tissue analyses. Results: Micro-CT and SR-PCI with 3D rendering revealed the extensive vascular plexus within the un-decalcified incus bone communicating with the exterior surface. The relationship between the vessels, lenticular process, and incudostape-dial joint were clearly observed. SR-PCI allowed for histologic-level detail while preserving the specimen and its 3D relationships. Conclusion: SR-PCI with 3D reconstructions confirmed the main vascular supply to the lenticular process along the intraosseous lenticular vessels. This is the first synchrotron analysis of a patient having undergone stapes surgery, and it suggests that incus necrosis associated with stapes surgery may be caused by a disruption of the lenticular blood flow induced by the prosthesis loop, and not by strangulation of mucosal vessels as has been previously described.
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| 10. |
- Helpard, Luke, et al.
(författare)
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An Approach for Individualized Cochlear Frequency Mapping Determined From 3D Synchrotron Radiation Phase-Contrast Imaging
- 2021
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 68:12, s. 3602-3611
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Cochlear implants are traditionally programmed to stimulate according to a generalized frequency map, where individual anatomic variability is not considered when selecting the centre frequency of stimulation of each implant electrode. However, high variability in cochlear size and spatial frequency distributions exist among individuals. Generalized cochlear implant frequency maps can result in large pitch perception errors and reduced hearing outcomes for cochlear implant recipients. The objective of this work was to develop an individualized frequency mapping technique for the human cochlea to allow for patient-specific cochlear implant stimulation.Methods: Ten cadaveric human cochleae were scanned using synchrotron radiation phase-contrast imaging (SR-PCI) combined with computed tomography (CT). For each cochlea, ground truth angle-frequency measurements were obtained in three-dimensions using the SR-PCI CT data. Using an approach designed to minimize perceptual error in frequency estimation, an individualized frequency function was determined to relate angular depth to frequency within the cochlea.Results: The individualized frequency mapping function significantly reduced pitch errors in comparison to the current gold standard generalized approach.Conclusion and Significance: This paper presents for the first time a cochlear frequency map which can be individualized using only the angular length of cochleae. This approach can be applied in the clinical setting and has the potential to revolutionize cochlear implant programming for patients worldwide.
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