1
|
Abstract
The motion of a spin excitation across topologically nontrivial magnetic order exhibits a deflection that is analogous to the effect of the Lorentz force on an electrically charged particle in an orbital magnetic field. We used polarized inelastic neutron scattering to investigate the propagation of magnons (i.e., bosonic collective spin excitations) in a lattice of skyrmion tubes in manganese silicide. For wave vectors perpendicular to the skyrmion tubes, the magnon spectra are consistent with the formation of finely spaced emergent Landau levels that are characteristic of the fictitious magnetic field used to account for the nontrivial topological winding of the skyrmion lattice. This provides evidence of a topological magnon band structure in reciprocal space, which is borne out of the nontrivial real-space topology of a magnetic order.
Collapse
|
2
|
Optimized signal deduction procedure for the MIEZE spectroscopy technique. J Appl Crystallogr 2022; 55:14-20. [PMID: 35145354 PMCID: PMC8805159 DOI: 10.1107/s1600576721011936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 11/10/2021] [Indexed: 12/03/2022] Open
Abstract
A method is reported to determine the phase and amplitude of sinusoidally modulated event rates, binned into four bins per oscillation, based on data generated at the resonant neutron spin-echo spectrometer RESEDA at FRM-II. The presented algorithm relies on a reconstruction of the unknown parameters. It omits a calculation-intensive fitting procedure and avoids contrast reduction due to averaging effects. It allows the current data acquisition bottleneck at RESEDA to be relaxed by a factor of four and thus increases the potential time resolution of the detector by the same factor. The approach is explained in detail and compared with the established fitting procedures of time series having four and 16 time bins per oscillation. In addition the empirical estimates of the errors of the three methods are presented and compared with each other. The reconstruction is shown to be unbiased, asymptotic and efficient for estimating the phase. Reconstructing the contrast increases the error bars by roughly 10% as compared with fitting 16 time-binned oscillations. Finally, the paper gives heuristic, analytical equations to estimate the error for phase and contrast as a function of their initial values and counting statistics.
Collapse
|
3
|
Evaluation of the inflammatory markers CCL8, CXCL5, and LIF in patients with anastomotic leakage after colorectal cancer surgery. Int J Colorectal Dis 2020; 35:1221-1230. [PMID: 32307587 PMCID: PMC7320065 DOI: 10.1007/s00384-020-03582-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/04/2020] [Indexed: 02/04/2023]
Abstract
PURPOSE Anastomotic leakage constitutes a dreaded complication after colorectal surgery, leading to increased morbidity and mortality as well as prolonged hospitalization. Most leakages become clinically apparent about 8 days after surgery; however, early detection is quintessential to reduce complications and to improve patients' outcome. We therefore investigated the significance of specific protein expression profiles as putative biomarkers, indicating anastomotic leakage. METHODS In this single-center prospective cohort study serum and peritoneal fluid samples-from routinely intraoperatively inserted drainages-of colorectal cancer patients were collected 3 days after colorectal resection. Twenty patients without anastomotic leakage and 18 patients with an anastomotic leakage and without other complications were included. Protein expression of seven inflammatory markers in serum and peritoneal fluid was assessed by multiplex ELISA and correlated with patients' clinical data. RESULTS Monocyte chemoattractant protein 2 (CCL8/MCP-2), leukemia-inhibiting factor (LIF), and epithelial-derived neutrophil-activating protein (CXCL5/ENA-78) were significantly elevated in peritoneal fluid but not in serum samples from patients subsequently developing anastomotic leakage after colorectal surgery. No expressional differences could be found between grade B and grade C anastomotic leakages. CONCLUSION Measurement 3 days after surgery revealed altered protein expression patterns of the inflammatory markers CCL8/MCP2, LIF, and CXCL5/ENA-78 in peritoneal fluid from patients developing anastomotic leakage after colorectal surgery. Further studies with a larger patient cohort with inclusion of different variables are needed to evaluate their potential as predictive biomarkers for anastomotic leakage.
Collapse
|
4
|
Time of flight modulation of intensity by zero effort on Larmor. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:125101. [PMID: 31893808 DOI: 10.1063/1.5123987] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/11/2019] [Indexed: 05/27/2023]
Abstract
A time-of-flight modulation of intensity by zero effort spectrometer mode has been developed for the Larmor instrument at the ISIS pulsed neutron source. The instrument utilizes resonant spin flippers that employ electromagnets with pole shoes, allowing the flippers to operate at frequencies up to 3 MHz. Tests were conducted at modulation frequencies of 103 kHz, 413 kHz, 826 kHz, and 1.03 MHz, resulting in a Fourier time range of ∼0.1 ns to 30 ns using a wavelength band of 4 Å-11 Å.
Collapse
|
5
|
ASSOCIATIONS OF CHILDHOOD TRAUMA AND ADULT RESILIENCE WITH HIPPOCAMPAL VOLUME IN LATE MIDLIFE. Innov Aging 2018. [DOI: 10.1093/geroni/igy023.1404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
6
|
DOES EDUCATION ENHANCE INTELLECTUAL ABILITY AND COGNITIVE RESERVE? EVIDENCE FOR A SENSITIVE PERIOD. Innov Aging 2018. [DOI: 10.1093/geroni/igy023.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
7
|
INTERACTIVE EFFECTS OF ALCOHOL CONSUMPTION AND APOE-E4 STATUS ON GENERAL COGNITIVE ABILITY IN MIDDLE-AGED MEN. Innov Aging 2018. [DOI: 10.1093/geroni/igy031.3563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
8
|
DEPRESSION, INFLAMMATION AND CARDIOVASCULAR BURDEN IN MIDDLE AGE TWINS. Innov Aging 2018. [DOI: 10.1093/geroni/igy023.2855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
9
|
Comprehensive measurements of intrauterine and postnatal exposure to lamotrigine. PHARMACOPSYCHIATRY 2018. [DOI: 10.1055/s-0038-1649539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
10
|
Abstract
The study aimed to investigate the possible anti-inflammatory activity of larch sawdust as feed supplement in lactating sows' diet and its possible effect on the prevalence of Postpartum Dysgalactia Syndrome under field conditions. In a Greek farrow-to-finish pig farm, fifteen sows were randomly and equally allocated to a negative control group (NC group), a positive control group (PC group), and a treatment group (LT group). The animals of the first two groups received 99% basic diet and 1% corn starch, while LT group animals received 99% basic diet and 1% larch sawdust. The whole trial period lasted 35 days (7 days prior to farrow - day of weaning). At parturition day, animals of the PC group received 2 ml of an anti-inflammatory drug intramuscularly (meloxicam, Metacam®, Boehringer Ingelheim Vetmedica), while the animals of both other groups, received 2 ml of normal saline. Results showed insignificant differences among experimental groups for parameters such as post-partum rectal temperature and piglets performance. On the contrary, a significant increase of mean milk lactation index was observed in LT and PC groups on the 4th day of lactation period, when compared with NC group (p=0.014). Additionally, mean IL-6 concentrations in blood in the LT group showed a tendency for reduction when compared with those found in NC, and insignificant difference (p>0.05) when compared with those observed in PC group 24 hours postpartum. Moreover, the respective TNFα mean level in the LT group at 24 and 72 hours after parturition was similar to that found in PC group, respectively) and significantly lower than that determined in the NC group (p=0.003, p=0.024. The results suggest a possible anti-inflammatory effect of larch sawdust in sows.
Collapse
|
11
|
Ultra-high vacuum compatible preparation chain for intermetallic compounds. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:113902. [PMID: 27910441 DOI: 10.1063/1.4967011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the development of a versatile material preparation chain for intermetallic compounds, which focuses on the realization of a high-purity growth environment. The preparation chain comprises an argon glovebox, an inductively heated horizontal cold boat furnace, an arc melting furnace, an inductively heated rod casting furnace, an optically heated floating-zone furnace, a resistively heated annealing furnace, and an inductively heated annealing furnace. The cold boat furnace and the arc melting furnace may be loaded from the glovebox by means of a load-lock permitting to synthesize compounds starting with air-sensitive elements while handling the constituents exclusively in an inert gas atmosphere. All furnaces are all-metal sealed, bakeable, and may be pumped to ultra-high vacuum. We find that the latter represents an important prerequisite for handling compounds with high vapor pressure under high-purity argon atmosphere. We illustrate the operational aspects of the preparation chain in terms of the single-crystal growth of the heavy-fermion compound CeNi2Ge2.
Collapse
|
12
|
Schwangerschaft bei Vena cava inferior (VCI)-Aplasie – Fallbericht einer interdisziplinären Herausforderung. Geburtshilfe Frauenheilkd 2016. [DOI: 10.1055/s-0036-1593309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
|
13
|
Successful Cryopreservation of Domestic Cat (Felis catus) Epididymal Sperm after Slow Equilibration to 15 or 10°C. Reprod Domest Anim 2016; 51:195-203. [DOI: 10.1111/rda.12666] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/16/2015] [Indexed: 11/29/2022]
|
14
|
In vivo assessment of an industrial waste product as a feed additive in dairy cows: Effects of larch (Larix decidua L.) sawdust on blood parameters and milk composition. Vet J 2015; 206:322-6. [PMID: 26526868 DOI: 10.1016/j.tvjl.2015.09.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 11/30/2022]
Abstract
When larch (Larix spp.) is processed in the wood industry, the sawdust is currently disposed of as waste or used as combustible material, even though it is rich in biologically active compounds. In this study the effect of larch sawdust supplementation on blood parameters as well as milk composition was examined in healthy mid-lactating dairy cows. Twenty-four multiparous Italian Friesian dairy cows were assigned to groups receiving either 300 g/day/cow of larch sawdust or a control diet, and treatments were continued for a 20 day period. Milk parameters were unaffected by treatment. A lower plasma total protein concentration was observed and can be attributed to a decrease in globulin concentration. A lower plasma urea concentration was also detected in the larch group. Moreover, biomarkers of liver function were influenced by the treatment. Total bilirubin was lower in larch-treated animals, and cholesterol tended to be lower. In addition, an interaction between day and treatment was observed for very low density lipoprotein. The concentration of other parameters, including reactive oxygen metabolites, superoxide dismutase, glutathione peroxidase and nitrotyrosine, did not differ between treatments. The observed benefits, together with the good palatability, make larch sawdust a promising candidate for the development of beneficial feed supplements for livestock. Further studies will be useful, particularly to evaluate its efficacy in different health conditions.
Collapse
|
15
|
Schwangerschaft bei maternaler Vena cava inferior-Aplasie (VCI) – ein Fallbericht. Z Geburtshilfe Neonatol 2015. [DOI: 10.1055/s-0035-1566539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
16
|
Back injuries in a cohort of schoolchildren aged 6-12: A 2.5-year prospective study. Scand J Med Sci Sports 2015; 26:911-8. [PMID: 26130046 DOI: 10.1111/sms.12519] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2015] [Indexed: 11/27/2022]
Abstract
The aims of this prospective school cohort study were to describe the epidemiology of diagnosed back pain in childhood, classified as either nontraumatic or traumatic back injury, and to estimate the association with physical activity in different settings. Over 2.5 years, 1240 children aged 6-12 years were surveyed weekly using mobile text messages to ask about the presence or absence of back pain. Pain was clinically diagnosed and injuries were classified using the International Classification of Diseases version 10. Physical activity data were obtained from text messages and accelerometers. Of the 315 back injuries diagnosed, 186 injuries were nontraumatic and 129 were traumatic. The incidence rate ratio was 1.5 for a nontraumatic back injury compared with a traumatic injury. The overall estimated back injury incidence rate was 0.20 per 1000 physical activity units (95% confidence interval 0.18-0.23). The back injury incidence rates were higher for sports when exposure per 1000 physical activity units was taken into consideration and especially children horse-riding had a 40 times higher risk of sustaining a traumatic back injury compared to the risk during non-organized leisure time physical activity. However, the reasonably low injury incidence rates support the recommendations of children continuously being physically active.
Collapse
|
17
|
Fine Tuning of CaV1.3 Ca2+ channel properties in adult inner hair cells positioned in the most sensitive region of the Gerbil Cochlea. PLoS One 2014; 9:e113750. [PMID: 25409445 PMCID: PMC4237458 DOI: 10.1371/journal.pone.0113750] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 10/28/2014] [Indexed: 01/15/2023] Open
Abstract
Hearing relies on faithful signal transmission by cochlear inner hair cells (IHCs) onto auditory fibres over a wide frequency and intensity range. Exocytosis at IHC ribbon synapses is triggered by Ca2+ inflow through CaV1.3 (L-type) Ca2+ channels. We investigated the macroscopic (whole-cell) and elementary (cell-attached) properties of Ca2+ currents in IHCs positioned at the middle turn (frequency ∼2 kHz) of the adult gerbil cochlea, which is their most sensitive hearing region. Using near physiological recordings conditions (body temperature and a Na+ based extracellular solution), we found that the macroscopic Ca2+ current activates and deactivates very rapidly (time constant below 1 ms) and inactivates slowly and only partially. Single-channel recordings showed an elementary conductance of 15 pS, a sub-ms latency to first opening, and a very low steady-state open probability (Po: 0.024 in response to 500-ms depolarizing steps at ∼−18 mV). The value of Po was significantly larger (0.06) in the first 40 ms of membrane depolarization, which corresponds to the time when most Ca2+ channel openings occurred clustered in bursts (mean burst duration: 19 ms). Both the Po and the mean burst duration were smaller than those previously reported in high-frequency basal IHCs. Finally, we found that middle turn IHCs are likely to express about 4 times more Ca2+ channels per ribbon than basal cells. We propose that middle-turn IHCs finely-tune CaV1.3 Ca2+ channel gating in order to provide reliable information upon timing and intensity of lower-frequency sounds.
Collapse
|
18
|
CD9-positive Mikropartikel in Follikelflüssigkeit – ein möglicher Einfluss auf das Reproduktionsgeschehen? Geburtshilfe Frauenheilkd 2014. [DOI: 10.1055/s-0034-1388010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|
19
|
Keine Korrelation uteriner und peripherer natürlicher Killerzellen bei Patientinnen mit habituellen Aborten und Implantationsversagen. Geburtshilfe Frauenheilkd 2014. [DOI: 10.1055/s-0034-1387967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|
20
|
Studien zum Vorgang der Wasserstoffübertragung, 76 [1]. Der anomale Verlauf der Elektroreduktion von Cumarin mit Lithium als Leitsalzkation: Versuche zur Reaktionslenkung durch Mediatoren / Studies on the Occurrence of Hydrogen Transfer, 76 [1] The Anomal Course of the Electroreduction of Coumarine with Supporting Electrolyts Containing Li+: Experiments to Influence the Reaction by Mediators. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znb-1985-0621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
In contradiction to the experience the hydrodimer is formed as the main product in the electroreduction of coumarine using lithium compounds as a supporting electrolyt. It is assumed that the lithium ions are coordinated internally with the radicalanion A resp. B derived from coumarine. In this way the hydrodimerization is favoured. From 18 different compounds added as possible mediators to the catholyt only pyridine influences moderately the ratio: hydrodimerizationproduct/dihydroproduct.
Collapse
|
21
|
Real-space and reciprocal-space Berry phases in the Hall effect of Mn(1-x)Fe(x)Si. PHYSICAL REVIEW LETTERS 2014; 112:186601. [PMID: 24856709 DOI: 10.1103/physrevlett.112.186601] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Indexed: 06/03/2023]
Abstract
We report an experimental and computational study of the Hall effect in Mn(1-x)Fe(x)Si, as complemented by measurements in Mn(1-x)Co(x)Si, when helimagnetic order is suppressed under substitutional doping. For small x the anomalous Hall effect (AHE) and the topological Hall effect (THE) change sign. Under larger doping the AHE remains small and consistent with the magnetization, while the THE grows by over a factor of 10. Both the sign and the magnitude of the AHE and the THE are in excellent agreement with calculations based on density functional theory. Our study provides the long-sought material-specific microscopic justification that, while the AHE is due to the reciprocal-space Berry curvature, the THE originates in real-space Berry phases.
Collapse
|
22
|
Efficacy and safety of telaprevir (TVR) triple therapy in a 'real-life' cohort of 102 patients with HCV genotype 1: interim analysis after 24 weeks of treatment. J Viral Hepat 2014; 21:333-40. [PMID: 24716636 DOI: 10.1111/jvh.12145] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/13/2013] [Indexed: 12/16/2022]
Abstract
Since 2011, telaprevir (TVR)-based triple therapy is the new treatment standard for hepatitis C genotype 1 virus infection. The aim of our retrospective interim analysis encompassing the first 24 weeks on TVR-based triple therapy was to assess 'real-life' antiviral efficacy and side effects in a large single-centre cohort, both in comparison with the data obtained in large prospective clinical trials. In total, we treated 102 patients: 24 treatment-naïve patients, 58 patients pretreated with PEG-IFN/RBV (thereof: 28 with nonresponse, 25 with relapse, five unknown) and 20 patients who previously had received nonpegylated interferon. 74 of 102 patients were assigned with HCV genotype 1b; 34 of 102 patients were treated in the context of liver cirrhosis. 72 of 102 patients have reached treatment week 24 (mean treatment duration 31 weeks). In the ITT analysis, overall response rates were at: week 4: 66%; week 12: 85%; and week 24: 78%. So far, 24 patients discontinued treatment prematurely, of those, 10 patients were due to virological failure. Haematological side effects were frequent (40% anaemia), as were 'flu-like' symptoms (94%), rash (65%) and pruritus (79%). According to our interim ITT analysis encompassing up to 24 weeks of TVR-based triple therapy, our 'real-life' antiviral effects are comparable to the results of large multicentric clinical trials. However, TVR-based triple therapy exhibited a high frequency of side effects requiring multiple therapeutic interventions. Notably, in our 'real-life' cohort, no lethal case was observed so far.
Collapse
|
23
|
OVERUSE AND TRAUMATIC MUSCULOSKELETAL EXTREMITY INJURIES IN SCHOOL CHILDREN. Br J Sports Med 2014. [DOI: 10.1136/bjsports-2014-093494.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
24
|
Musculoskeletal extremity injuries in a cohort of schoolchildren aged 6-12: A 2.5-year prospective study. Scand J Med Sci Sports 2014; 25:251-8. [DOI: 10.1111/sms.12177] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2013] [Indexed: 11/28/2022]
|
25
|
Autonomous functions of murine thyroid hormone receptor TRα and TRβ in cochlear hair cells. Mol Cell Endocrinol 2014; 382:26-37. [PMID: 24012852 DOI: 10.1016/j.mce.2013.08.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/22/2013] [Accepted: 08/29/2013] [Indexed: 11/18/2022]
Abstract
Thyroid hormone acts on gene transcription by binding to its nuclear receptors TRα1 and TRβ. Whereas global deletion of TRβ causes deafness, global TRα-deficient mice have normal hearing thresholds. Since the individual roles of the two receptors in cochlear hair cells are still unclear, we generated mice with a hair cell-specific mutation of TRα1 or deletion of TRβ using the Cre-loxP system. Hair cell-specific TRβ mutant mice showed normal hearing thresholds but delayed BK channel expression in inner hair cells, slightly stronger outer hair cell function, and slightly reduced amplitudes of auditory brainstem responses. In contrast, hair cell-specific TRα mutant mice showed normal timing of BK channel expression, slightly reduced outer hair cell function, and slightly enhanced amplitudes of auditory brainstem responses. Our data demonstrate that TRβ-related deafness originates outside of hair cells and that TRα and TRβ play opposing, non-redundant roles in hair cells. A role for thyroid hormone receptors in controlling key regulators that shape signal transduction during development is discussed. Thyroid hormone may act through different thyroid hormone receptor activities to permanently alter the sensitivity of auditory neurotransmission.
Collapse
|
26
|
Sediments in urban river basins: identification of sediment sources within the Lago Paranoá catchment, Brasilia DF, Brazil - using the fingerprint approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 466-467:513-523. [PMID: 23933453 DOI: 10.1016/j.scitotenv.2013.07.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 06/02/2023]
Abstract
The development of effective sediment management strategies is a key requirement in tropical areas with fast urban development, like Brasilia DF, Brazil, because of the limited resources available. Accurate identification and management of sediment sources areas, however, is hampered by the dearth of reliable information on the primary sources of sediment. Few studies have attempted to quantify the source of sediment within fast urbanizing, mixed used, tropical catchments. In this study, statistically verified composite fingerprints and a multivariate mixing model have been used to identify the main land use specific sources of sediment deposited in the artificial Lago Paranoá, Central Brazil. Because of the variability of urban land use types within the Lago Paranoá sub-catchments, the fingerprinting approach was additionally undertaking for the Riacho Fundo sub-catchment. The main contributions from individual source types (i.e. surface materials from residential areas, constructions sites, road deposited sediment, cultivated areas, pasture, farm tracks, woodland and natural gullies) varied between the whole catchment and the Riacho Fundo sub-catchment, reflecting the different proportions of land uses. The sediments deposited in the silting zones of the Lago Paranoá originate largely from urban sources (85 ± 4%). Areas with (semi-) natural vegetation and natural gullies contribute 10 ± 2% of the sediment yield. Agricultural sites have only a minor sediment contribution of about 5 ± 4% within the whole catchment. Within the Riacho Fundo sub-catchment there is a significant contribution from urban (53 ± 4%) source, such as residential areas with semi-detached housings (42 ± 3%) with unpaved roads (12 ± 3%) and construction sites (20 ± 3%) and agricultural areas (31 ± 2%). The relative contribution from land use specific sources to the sediment deposition in the silting zone of the Lago Paranoá demonstrated that most of the sediment is derived from sites with high anthropogenic impact.
Collapse
|
27
|
Overuse and traumatic extremity injuries in schoolchildren surveyed with weekly text messages over 2.5 years. Scand J Med Sci Sports 2013; 24:807-13. [DOI: 10.1111/sms.12095] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2013] [Indexed: 11/28/2022]
|
28
|
Procoagulant tissue factor-exposing vesicles in human seminal fluid. J Reprod Immunol 2013; 98:45-51. [DOI: 10.1016/j.jri.2013.02.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 01/21/2013] [Accepted: 02/10/2013] [Indexed: 12/18/2022]
|
29
|
Burst activity and ultrafast activation kinetics of CaV1.3 Ca²⁺ channels support presynaptic activity in adult gerbil hair cell ribbon synapses. J Physiol 2013; 591:3811-20. [PMID: 23713031 PMCID: PMC3764630 DOI: 10.1113/jphysiol.2013.251272] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Auditory information transfer to afferent neurons relies on precise triggering of neurotransmitter release at the inner hair cell (IHC) ribbon synapses by Ca2+ entry through CaV1.3 Ca2+ channels. Despite the crucial role of CaV1.3 Ca2+ channels in governing synaptic vesicle fusion, their elementary properties in adult mammals remain unknown. Using near-physiological recording conditions we investigated Ca2+ channel activity in adult gerbil IHCs. We found that Ca2+ channels are partially active at the IHC resting membrane potential (−60 mV). At −20 mV, the large majority (>70%) of Ca2+ channel first openings occurred with an estimated delay of about 50 μs in physiological conditions, with a mean open time of 0.5 ms. Similar to other ribbon synapses, Ca2+ channels in IHCs showed a low mean open probability (0.21 at −20 mV), but this increased significantly (up to 0.91) when Ca2+ channel activity switched to a bursting modality. We propose that IHC Ca2+ channels are sufficiently rapid to transmit fast signals of sound onset and support phase-locking. Short-latency Ca2+ channel opening coupled to multivesicular release would ensure precise and reliable signal transmission at the IHC ribbon synapse.
Collapse
|
30
|
Geochemical signature and properties of sediment sources and alluvial sediments within the Lago Paranoá catchment, Brasilia DF: a study on anthropogenic introduced chemical elements in an urban river basin. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 452-453:411-420. [PMID: 23542435 DOI: 10.1016/j.scitotenv.2013.02.077] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/12/2013] [Accepted: 02/19/2013] [Indexed: 06/02/2023]
Abstract
One of the largest urban agglomerations in Brazil is the capital Brasilia and its surrounding area. Due to fast urban sprawl and accelerated land use changes, available water supplies are near their limits. The water supply depends largely on surface water collected in reservoirs. There are increasing concerns regarding water shortages due to sediment aggradations, and of water quality due to geochemical modification of sediments from human activities. The concentration of 18 chemical elements and five sediment properties was analyzed from different potential land-based sediment sources and deposited alluvial sediment within the Lago Paranoà catchment. The goal of this study was to assess the distribution of chemical elements and geochemical/physical properties of potential sediment sources in the Lago Paranoá catchment. Principal component analysis and hierarchical cluster analysis were used to investigate the influence of different land use types on the geochemistry of sediments. Geochemical fingerprints of anthropogenic activities were developed based on the results of the cluster analysis grouping. The anthropogenic input of land use specific geochemical elements was examined and quantified by the calculation of enrichment factors using the local geological background as reference. Through comparison of the geochemical signature of potential sediment sources and alluvial sediments of the Lago Paranoá and sub-catchments, the relative contribution of land use specific sediment sources to the sediment deposition of the main water reservoir were estimated. The existing findings suggest a strong relationship between land use and quantifiable features of sediment geochemistry and indicate that urban land use had the greatest responsibility for recent silting in the Lago Paranoá. This assessment helps to characterize the role of human activities in mixed-used watersheds on sediment properties, and provides essential information to guide management responses towards more effective source-reduction strategies.
Collapse
|
31
|
Development and function of the voltage-gated sodium current in immature mammalian cochlear inner hair cells. PLoS One 2012; 7:e45732. [PMID: 23029208 PMCID: PMC3446918 DOI: 10.1371/journal.pone.0045732] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 08/14/2012] [Indexed: 12/19/2022] Open
Abstract
Inner hair cells (IHCs), the primary sensory receptors of the mammalian cochlea, fire spontaneous Ca2+ action potentials before the onset of hearing. Although this firing activity is mainly sustained by a depolarizing L-type (CaV1.3) Ca2+ current (ICa), IHCs also transiently express a large Na+ current (INa). We aimed to investigate the specific contribution of INa to the action potentials, the nature of the channels carrying the current and whether the biophysical properties of INa differ between low- and high-frequency IHCs. We show that INa is highly temperature-dependent and activates at around −60 mV, close to the action potential threshold. Its size was larger in apical than in basal IHCs and between 5% and 20% should be available at around the resting membrane potential (−55 mV/−60 mV). However, in vivo the availability of INa could potentially increase to >60% during inhibitory postsynaptic potential activity, which transiently hyperpolarize IHCs down to as far as −70 mV. When IHCs were held at −60 mV and INa elicited using a simulated action potential as a voltage command, we found that INa contributed to the subthreshold depolarization and upstroke of an action potential. We also found that INa is likely to be carried by the TTX-sensitive channel subunits NaV1.1 and NaV1.6 in both apical and basal IHCs. The results provide insight into how the biophysical properties of INa in mammalian cochlear IHCs could contribute to the spontaneous physiological activity during cochlear maturation in vivo.
Collapse
|
32
|
Coincident Diagnosis of a Pulmonary Abscess and Ascaris lumbricoides Infection: a Possible Causal Connection? KLINISCHE PADIATRIE 2012; 224:469-70. [DOI: 10.1055/s-0032-1321732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
33
|
Ergic2, a brain specific interacting partner of Otoferlin. Cell Physiol Biochem 2012; 29:941-8. [PMID: 22613993 DOI: 10.1159/000188338] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Otoferlin, a postulated calcium sensor of 230 kDa, was proposed to trigger calcium dependent fusion of vesicles with plasma membrane in the ribbon synapses of cochlear IHCs. Otoferlin's interaction with Rab8b and Myo6, proteins involved in the intracellular membrane trafficking, extended the previous hypothesis assigning Otoferlin an additional role in trans-Golgi trafficking. Here, we present another Otoferlin binding partner, Ergic2, a protein with a still unknown function but presenting sequence homology to other proteins involved in ER/Golgi vesicle trafficking. METHODS Novel binding partners of Otoferlin were searched by yeast two-hybrid screening in a rodent cochlear cDNA library (P3-P15). RT-PCR, western blot, immunohistochemistry staining and co-immunoprecipitation were applied to analyze and confirm an interaction between Ergic2 and Otoferlin. RESULTS The Y-2-H screening, using baits covering parts of Otoferlin's C2D domain, identified Ergic2 as an interacting protein for Otoferlin. Both are co-expressed (mRNA and protein level) in rodent cochlea and brain before- and after-onset of hearing. By RT-PCR Ergic2 was detected in cochlear IHCs and OHCs and in brain regions where Otoferlin is known to be present. Co-localization studies revealed an overlap of Ergic2 and Otoferlin signals in IHCs and neurons of cerebral cortical layer I making Ergic2 the promising binding candidate. However, while Ergic2 was co-precipitated by an anti-Otoferlin antibody in protein lysates from murine brain, this specific protein interaction was not detected in cochlea. CONCLUSION Our new data on Otoferlin's interactome suggest that Otoferlin can form different, tissue-specific protein complexes.
Collapse
|
34
|
To clot or not to clot: Procoagulant vesicles in human seminal fluid. J Reprod Immunol 2012. [DOI: 10.1016/j.jri.2012.03.265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
35
|
Altered phenotype of the vestibular organ in GLAST-1 null mice. J Assoc Res Otolaryngol 2012; 13:323-33. [PMID: 22350511 DOI: 10.1007/s10162-011-0311-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 12/21/2011] [Indexed: 01/11/2023] Open
Abstract
Various studies point to a crucial role of the high-affinity sodium-coupled glutamate aspartate transporter GLAST-1 for modulation of excitatory transmission as shown in the retina and the CNS. While 2-4-month-old GLAST-1 null mice did not show any functional vestibular abnormality, we observed profound circling behavior in older (7 months) animals lacking GLAST-1. An unchanged total number of otoferlin-positive vestibular hair cells (VHCs), similar ribbon numbers in VHCs, and an unchanged VGLUT3 expression in type II VHCs were detected in GLAST-1 null compared to wild-type mice. A partial loss of supporting cells and an apparent decline of a voltage-gated channel potassium subunit (KCNQ4) was observed in postsynaptic calyceal afferents contacting type I VHCs, together with a reduction of neurofilament- (NF200-) and vesicular glutamate transporter 1- (VGLUT1-) positive calyces in GLAST-1 null mice. Taken together, GLAST-1 deletion appeared to preferentially affect the maintenance of a normal postsynaptic/neuronal phenotype, evident only with increasing age.
Collapse
|
36
|
|
37
|
FEMALE (IN)FERTILITY. Hum Reprod 2012. [DOI: 10.1093/humrep/27.s2.80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
38
|
Essential oil composition and antioxidant activity ofStachys sylvaticaL. (Lamiaceae) from different wild populations in Kosovo. Nat Prod Res 2011; 26:1676-81. [PMID: 22010786 DOI: 10.1080/14786419.2011.613384] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
39
|
Chemical composition and antimicrobial activity of Cymbopogon citratus and Cymbopogon giganteus essential oils alone and in combination. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2011; 18:1070-1074. [PMID: 21665450 DOI: 10.1016/j.phymed.2011.05.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/11/2011] [Accepted: 05/01/2011] [Indexed: 05/30/2023]
Abstract
As part of ongoing research on the chemical composition and the antimicrobial properties of Burkinabe plants essential oils alone and in combination, essential oils (EOs) from leaves of Cymbopogon citratus and Cymbopogon giganteus from Burkina Faso were analyzed by GC-FID and GC-MS. Five constituents, which accounted for 96.3% of the oil, were identified in the EO of C. citratus. Geranial (48.1%), neral (34.6%) and myrcene (11.0%) were the major constituents. For C. giganteus a total of eight compounds were identified which represented 86.0% of the oils extracted. The dominant compounds were limonene (42%) and a set of monoterpene alcohols: trans-p-mentha-1(7),8-dien-2-ol (14.2%), cis-p-mentha-1(7),8-dien-2-ol (12%), trans-p-mentha-2,8-dien-1-ol (5.6%) and cis-p-mentha-2,8-dien-1-ol (5.2%). The EOs were tested against nine bacteria by using disc diffusion and microdilution methods. C. giganteus EO showed antimicrobial effects against all microorganisms tested whereas C. citratus EO failed to inhibit Pseudomonas aeruginosa. The antimicrobial activity of combinations of the two EOs was quantified by the checkerboard method. Combinations of the two EOs exerted synergistic, additive and indifferent antimicrobial effects. Results of the present investigation provide evidence that the combinations of plant EOs could be assessed for synergistic activity in order to reduce their minimum effective dose.
Collapse
|
40
|
|
41
|
Fas and Fas-ligand expression in normal and disturbed pregnancy. J Reprod Immunol 2011. [DOI: 10.1016/j.jri.2011.06.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
42
|
Polymer Dynamics of Polybutadiene in Nanoscopic Confinement As Revealed by Field Cycling 1H NMR. Macromolecules 2011. [DOI: 10.1021/ma2002504] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
43
|
Eps8 regulates hair bundle length and functional maturation of mammalian auditory hair cells. PLoS Biol 2011; 9:e1001048. [PMID: 21526224 PMCID: PMC3079587 DOI: 10.1371/journal.pbio.1001048] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/09/2011] [Indexed: 12/20/2022] Open
Abstract
Hair cells of the mammalian cochlea are specialized for the dynamic coding of sound stimuli. The transduction of sound waves into electrical signals depends upon mechanosensitive hair bundles that project from the cell's apical surface. Each stereocilium within a hair bundle is composed of uniformly polarized and tightly packed actin filaments. Several stereociliary proteins have been shown to be associated with hair bundle development and function and are known to cause deafness in mice and humans when mutated. The growth of the stereociliar actin core is dynamically regulated at the actin filament barbed ends in the stereociliary tip. We show that Eps8, a protein with actin binding, bundling, and barbed-end capping activities in other systems, is a novel component of the hair bundle. Eps8 is localized predominantly at the tip of the stereocilia and is essential for their normal elongation and function. Moreover, we have found that Eps8 knockout mice are profoundly deaf and that IHCs, but not OHCs, fail to mature into fully functional sensory receptors. We propose that Eps8 directly regulates stereocilia growth in hair cells and also plays a crucial role in the physiological maturation of mammalian cochlear IHCs. Together, our results indicate that Eps8 is critical in coordinating the development and functionality of mammalian auditory hair cells.
Collapse
|
44
|
Abstract
1. Plants and their biologically active chemical constituents, sometimes called secondary metabolites or bioactives, present numerous opportunities for the improvement of livestock production by inclusion in the diet. 2. Many such plant derived materials have well established therapeutic values in man; however, their potential as feed additives in animal production, particularly of poultry, remains largely unexploited. 3. There is increasing evidence indicating that they can be efficient in controlling diseases, and plant bioactives may also influence production parameters such as feed efficiency and product quality. 4. It has been reported that they may even replicate some of the effects of antibiotic growth promoters, which were banned from use in Europe from 2006. 5. This review assesses the status of plant bioactives in poultry production and their mode of action on avian physiology, particularly in the digestive tract.
Collapse
|
45
|
Temperature Influences Thymol and Carvacrol Differentially inOriganumspp. (Lamiaceae). JOURNAL OF ESSENTIAL OIL RESEARCH 2010. [DOI: 10.1080/10412905.2010.9700359] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
46
|
Essential oils and aromatic plants in animal feeding - a European perspective. A review. FLAVOUR FRAG J 2010. [DOI: 10.1002/ffj.1967] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
47
|
Skyrmion lattices in metallic and semiconducting B20 transition metal compounds. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:164207. [PMID: 21386413 DOI: 10.1088/0953-8984/22/16/164207] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
High pressure studies in MnSi suggest the existence of a non-Fermi liquid state without quantum criticality. The observation of partial magnetic order in a small pocket of the pressure versus temperature phase diagram of MnSi has additionally inspired several proposals of complex spin textures in chiral magnets. We used neutron scattering to observe the formation of a two-dimensional lattice of skyrmion lines, a type of magnetic vortices, under applied magnetic fields in metallic and semiconducting B20 compounds. In strongly disordered systems the skyrmion lattice is hysteretic and extends over a large temperature range. Our study experimentally establishes magnetic materials lacking inversion symmetry as an arena for new forms of spin order composed of topologically stable spin textures.
Collapse
|
48
|
Effects of 8 weeks of vibration training at different frequencies (1 or 15 Hz) in senior sportsmen on torque and force development and of 1 year of training on muscle fibers. Neurol Res 2010; 32:26-31. [PMID: 20092692 DOI: 10.1179/016164110x12556180206310] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVE To examine the effects of 8 weeks of vibration training at different frequencies (1 and 15 Hz) on maximal isometric torque and force development in senior sportsmen, and of 1 year of heavy-resistance and vibration trainings on muscle fibers. METHODS Seven healthy senior sportsmen (mean age: 69.0 +/- 5.4 years) performed an 8 weeks of strength training of knee extensors. Vibrations were applied vertically to the axis of movement during training. One leg of each subject was trained at a frequency of 1 Hz, while the other leg was trained at 15 Hz. Measures of isometric peak torque (at knee-angles of 60, 90 and 120 degrees ) and force development were recorded before and after training. Four sportsmen continued a year-long heavy-resistance training adding every second week a session of vibration training. After training, muscle biopsies were harvested from their quadriceps muscles and used for structural analyses. Morphometry of muscle fibers was performed by light microscopy. Immunohistochemistry using anti-MHCemb and anti-N-CAM antibodies was performed to measure potential muscle damage. Data from muscle morphometry were compared to that of a series of vastus lateralis biopsies harvested from 12 young sportsmen and four healthy elderly. RESULTS Our results showed a significant increase in isometric peak torque at both 1 and 15 Hz vibration frequency in all three measured angles of the knee. There was no significant difference between the two frequencies, but we could find a higher increase in percentage of maximum power after the 1 Hz training. The results of force development showed a slight increase at the 1 Hz training in measured time frames from 0 to 50 and 200 ms, without statistical significance. A trend to significance was found at the 1 Hz training at the time window up to 200 ms. The 15 Hz training showed no significant changes of force development. Muscle biopsies show that the muscles of these well trained senior sportsmen contain muscle fibers which are 35% larger than those of sedentary elderly and, unexpectedly, 10% larger than those of young sportsmen. Despite 1 year of heavy resistance and vibration training, no evidence of muscle damage or denervation/reinnervation could be observed by light microscopy analyses, ATPase histochemistry and immunohistochemistry using anti-N-CAM or anti-MHC-emb antibodies. DISCUSSION Integration of vibration to conventional strength training in elderly sportsmen induces similar improvement of isometric peak torque and force development independently from the vibration frequency after 8 weeks of training, and long-term results in the surprising evidence of hypertrophic muscle fibers larger than those of young active sportsmen. The observation that the vibration training with low frequency is safe opens the possibility to test these rehabilitation procedures in sedentary elderly.
Collapse
|
49
|
Abstract
Mammalian cochlear inner hair cells (IHCs) are specialized to process developmental signals during immature stages and sound stimuli in adult animals. These signals are conveyed onto auditory afferent nerve fibres. Neurotransmitter release at IHC ribbon synapses is controlled by L-type CaV1.3 Ca2+ channels, the biophysics of which are still unknown in native mammalian cells. We have investigated the localization and elementary properties of Ca2+ channels in immature mouse IHCs under near-physiological recording conditions. CaV1.3 Ca2+ channels at the cell pre-synaptic site co-localize with about half of the total number of ribbons present in immature IHCs. These channels activated at about −70 mV, showed a relatively short first latency and weak inactivation, which would allow IHCs to generate and accurately encode spontaneous Ca2+ action potential activity characteristic of these immature cells. The CaV1.3 Ca2+ channels showed a very low open probability (about 0.15 at −20 mV: near the peak of an action potential). Comparison of elementary and macroscopic Ca2+ currents indicated that very few Ca2+ channels are associated with each docked vesicle at IHC ribbon synapses. Finally, we found that the open probability of Ca2+ channels, but not their opening time, was voltage dependent. This finding provides a possible correlation between presynaptic Ca2+ channel properties and the characteristic frequency/amplitude of EPSCs in auditory afferent fibres.
Collapse
|
50
|
Otoferlin interacts with myosin VI: implications for maintenance of the basolateral synaptic structure of the inner hair cell. Hum Mol Genet 2009; 18:2779-90. [PMID: 19417007 DOI: 10.1093/hmg/ddp213] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Otoferlin has been proposed to be the Ca(2+) sensor in hair cell exocytosis, compensating for the classical synaptic fusion proteins synaptotagmin-1 and synaptotagmin-2. In the present study, yeast two-hybrid assays reveal myosin VI as a novel otoferlin binding partner. Co-immunoprecipitation assay and co-expression suggest an interaction of both proteins within the basolateral part of inner hair cells (IHCs). Comparison of otoferlin mutants and myosin VI mutant mice indicates non-complementary and complementary roles of myosin VI and otoferlin for synaptic maturation: (i) IHCs from otoferlin mutant mice exhibited a decoupling of CtBP2/RIBEYE and Ca(V)1.3 and severe reduction of exocytosis. (ii) Myosin VI mutant IHCs failed to transport BK channels to the membrane of the apical cell regions, and the exocytotic Ca(2+) efficiency did not mature. (iii) Otoferlin and myosin VI mutant IHCs showed a reduced basolateral synaptic surface area and altered active zone topography. Membrane infoldings in otoferlin mutant IHCs indicated disturbed transport of endocytotic membranes and link the above morphological changes to a complementary role of otoferlin and myosin VI in transport of intracellular compartments to the basolateral IHC membrane.
Collapse
|