Severe hearing loss and outer hair cell death in homozygous Foxo3 knockout mice after moderate noise exposure

Noise induced hearing loss (NIHL) is a disease that affects millions of Americans. Identifying genetic pathways that influence recovery from noise exposure is an important step forward in understanding NIHL. The transcription factor Foxo3 integrates the cellular response to oxidative stress and plays a role in extending lifespan in many organisms, including humans. Here we show that Foxo3 is required for auditory function after noise exposure in a mouse model system, measured by ABR. Absent Foxo3, outer hair cells are lost throughout the middle and higher frequencies. SEM reveals persistent damage to some surviving outer hair cell stereocilia. However, DPOAE analysis reveals that some function is preserved in low frequency outer hair cells, despite concomitant profound hearing loss. Inner hair cells, auditory synapses and spiral ganglion neurons are all present after noise exposure in the Foxo3KO/KO fourteen days post noise (DPN). We also report anti-Foxo3 immunofluorescence in adult human outer hair cells. Taken together, these data implicate Foxo3 and its transcriptional targets in outer hair cell survival after noise damage. An additional role for Foxo3 in preserving hearing is likely, as low frequency auditory function is absent in noise exposed Foxo3KO/KOs even though all cells and structures are present

Deletion of the Notch ligand Jagged1 during cochlear maturation leads to inner hair cell defects and hearing loss

The mammalian cochlea is an exceptionally well-organized epithelium composed of hair cells, supporting cells, and innervating neurons. Loss or defects in any of these cell types, particularly the specialized sensory hair cells, leads to deafness. The Notch pathway is known to play a critical role in the decision to become either a hair cell or a supporting cell during embryogenesis; however, little is known about how Notch functions later during cochlear maturation. Uniquely amongst Notch ligands, Jagged1 (JAG1) is localized to supporting cells during cell fate acquisition and continues to be expressed into adulthood. Here, we demonstrate that JAG1 in maturing cochlear supporting cells is essential for normal cochlear function. Specifically, we show that deletion of JAG1 during cochlear maturation disrupts the inner hair cell pathway and leads to a type of deafness clinically similar to auditory neuropathy. Common pathologies associated with disruptions in inner hair cell function, including loss of hair cells, synapses, or auditory neurons, were not observed in JAG1 mutant cochleae. Instead, RNA-seq analysis of JAG1-deficient cochleae identified dysregulation of the Rho GTPase pathway, known to be involved in stereocilia development and maintenance. Interestingly, the overexpression of one of the altered genes, Diaph3, is responsible for autosomal dominant auditory neuropathy-1 (AUNA1) in humans and mice, and is associated with defects in the inner hair cell stereocilia. Strikingly, ultrastructural analyses of JAG1-deleted cochleae revealed stereocilia defects in inner hair cells, including fused and elongated bundles, that were similar to those stereocilia defects reported in AUNA1 mice. Taken together, these data indicate a novel role for Notch signaling in normal hearing development through maintaining stereocilia integrity of the inner hair cells during cochlear maturation

Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp

We have pursued two different methods to analyze the old stellar population near the Galactic plane, using data from the 2MASS survey. The first method is based on the isolation of the red clump giant population in the color-magnitude diagrams and the inversion of its star counts to obtain directly the density distribution along the line of sight. The second method fits the parameters of a disc model to the star counts in 820 regions. Results from both independent methods are consistent with each other. The qualitative conclusions are that the disc is well fitted by an exponential distribution in both the galactocentric distance and height. There is not an abrupt cut-off in the stellar disc (at least within R<15 kpc). There is a strong flare (i.e. an increase of scale-height towards the outer Galaxy) which begins well inside the solar circle, and hence there is a decrease of the scale-height towards the inner Galaxy. Another notable feature is the existence of a warp in the old stellar population whose amplitude is coincident with the amplitude of the gas warp. It is shown for low latitude stars (mean height: |z|~300 pc) in the outer disc (galactocentric radius R>6 kpc) that: the scale-height in the solar circle is h_z(R_sun)=3.6e-2 R_sun, the scale-length of the surface density is h_R=0.42 R_sun and the scale-length of the space density in the plane (i.e. including the effect of the flare) is H=0.25 R_sun. The variation of the scale-height due to the flare follows roughly a law h_z(R) =~ h_z(R_sun) exp [(R-R_\odot)/([12-0.6R(kpc)] kpc)] (for R<~15 kpc; R_sun=7.9 kpc). The warp moves the mean position of the disc to a height z_w=1.2e-3 R(kpc)^5.25 sin(phi+(5 deg.)) pc (for R<~13 kpc; R_sun=7.9 kpc).Comment: LaTEX, 20 pages, 23 figures, accepted to be published in A&

Метаболиты витамина D: роль в диагностике и терапии витамин-D-зависимых патологий

Most studies on the relationship between vitamin D and various pathologies use only one of the metabolites of vitamin D-25-hydroxyvitamin D3 (25(OH)D3). Hence, the potential effects associated with changes in the levels of other vitamin D metabolites remain outside of the focus of most researchers. In this paper we analyze the known biotransformations of cholecalciferol, possible errors in the assessment of D deficiency related to the properties of various metabolites of vitamin D3, a fundamental biologicaL roLe of the different metabolites of vitamin D3, and prospects for the use of the determination of vitamin D3 metabolite levels for clinical diagnostics.В большинстве исследований по изучению взаимосвязи между витамином D и заболеваниями изучаются ассоциации только одного из метаболитов витамина D-25-гидроксивитамина D3 (25(OH)D3). При этом потенциальные эффекты уровней других метаболитов витамина D остаются вне внимания большинства исследователей. В настоящей работе рассмотрены биотрансформации холекальциферола, возможные ошибки в оценке дефицита D (связанные со свойствами тех или иных метаболитов витамина D3), фундаментальные биологические роли метаболитов витамина D3 и перспективы использования оценок уровней метаболитов витамина D3 для клинической диагностики

Effects of the inclusion of alfacalcidol in complex rehabilitation programs for patients with age-related facial ptosis

Introduction. The sufficiency of vitamin D is important for slowing down the aging of the skin, maintaining its hydration, elasticity and the ability to regenerate. Biologically active forms of vitamin D (including alfacalcidol) promote the activation of genes whose function is directly related to the maintenance of the structure of the skin, subcutaneous tissue, fascia and muscle fibers.The aim of the work was to assess the prospects for the inclusion of alfacalcidol (“Alpha D3”, 0.25 μg, 1 caps/day) in the rehabilitation programs of patients with age-related ptosis of the face (n = 40, age 47 ± 5 years).Materials and methods. 4 groups of patients with age-related facial ptosis (n = 40, average age 47 ± 5 years) were observed for 60 days; measurements were made before and after clinical trials. Group 1A (first treatment, n = 12) received the daily dose of Alpha D3, 0.25 mg, in the morning, for 60 days, during this period the patients received 4 cosmetic procedures (2 plastic face massages and 2 stimulation current therapies). Group 1B (first control, n = 8) received only 4 cosmetic procedures over 60 days (2 plastic face massages and 2 stimulation current therapies). Group 2A (second treatment, n = 12) received the daily dose of ALFA D3, 0.25 mg, for 60 days, during this period the patients received 4 DMAE (diethylaminoethanol) mesotherapy procedures. Group 2B (second control, n = 8) only received 4 DMAE (diethylaminoethanol) mesotherapy procedures.Results. Alfacalcidol intake significantly increased the concentrations of 25 (OH) D (from 17 ± 5 ng/ml to 27 ± 8 ng/ml, P = 0.001) and calcium (from 86 ± 10 mg/L to 96 ± 6 mg/L, P = 0.01) in serum. The positive dynamics of the concentrations of 25 (OH) D and calcium when taking alfacalcidol corresponded to an increase in the total bone mineral density (+ 0.03 ± 0.03 g/cm3, control: + 0.006 ± 0.03, P = 0.016) and T-criterion (+0.4 ± 0.5, control: -0.07 ± 0.2, P = 0.0002), which indicates compensation for vitamin D deficiency and an improvement in bone metabolism. An increase in the levels of 25 (OH) D and calcium when taking alfacalcidol was accompanied by a positive trend in skin condition according to bioimpedance measurements. Taking the drug significantly increased the moisture content of the facial skin (from 17 ± 14 points to 29 ± 14 points, P = 0.055, without changes in the control) and increased the amplitude of the muscle motor response to the stimulus (+ 0.24 ± 0.22, P &lt; 0.02).Conclusions. Within the framework of a randomized design, it was shown that the addition of massage, microcurrent therapy, mesotherapy with alfacalcidol led to a significant increase in serum 25 (OH) D levels, an increase in skin elasticity and hydration, a decrease in visceral fat according to bioimpedance measurements, and an improvement in indicators of muscle contractility and neuromuscular signal transmission according to electromyography data and an increase in bone mineral density

Activated notch causes deafness by promoting a supporting cell phenotype in developing auditory hair cells.

To determine whether activated Notch can promote a supporting cell fate during sensory cell differentiation in the inner ear.An activated form of the Notch1 receptor (NICD) was expressed in early differentiating hair cells using a Gfi1-Cre mouse allele. To determine the effects of activated Notch on developing hair cells, Gfi1-NICD animals and their littermate controls were assessed at 5 weeks for hearing by measuring auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). The differentiation of NICD-expressing hair cells was assessed at postnatal day (P) 6, 11 and 20, using histological and molecular markers for hair cells, as well as supporting cells/progenitor cells. We also examined whether the effects of Notch were mediated by SOX2, a gene expressed in supporting cells and a likely downstream target of Notch, by crossing an inducible form of SOX2 to the Gfi1-Cre.Activation of Notch1 in developing auditory hair cells causes profound deafness. The NICD-expressing hair cells switch off a number of hair cell markers and lose their characteristic morphology. Instead, NICD-expressing hair cells adopt a morphology resembling supporting cells and upregulate a number of supporting cell markers. These effects do not appear to be mediated by SOX2, because although expression of SOX2 caused some hearing impairment, the SOX2-expressing hair cells did not downregulate hair cell markers nor exhibit a supporting cell-like phenotype.Our data show that Notch signaling inhibits hair cell differentiation and promotes a supporting cell-like phenotype, and that these effects are unlikely to be mediated by SOX2

The mature supporting cell marker NKAα1 is upregulated in NICD-expressing inner and outer hair cells.

<p>A–F. Paraffin sections from Gfi1-NICD and Cre-negative control cochleae at P20. A–C. Control sections showing the normal expression of NKAα1 in the phalangeal cells (phc) surrounding the inner hair cells (ihc), which are also coexpressed with SOX2. Deiter's cells also show expression of SOX2, although not NKAα1. D–F. Gfi1-NICD expressing inner hair cell has upregulated NKAα1 (arrowhead). Surprisingly, the NICD-expressing outer hair cells (ohc) have also upregulated NKAα1, although much more weakly than in the inner hair cells. Both inner and outer hair cells also show upregulation of SOX2. Scale bar = 100 microns.</p

NICD-expressing inner hair cells show morphology changes and abnormal P27KIP1 expression at P11.

<p>A–D. Paraffin sections from Gfi1-NICD cochlea and littermate controls at P11. A′-D′ show higher power views of the inner hair cells, which demonstrate morphological and molecular changes due to Notch activation. The changes in the inner hair cells in the Gfi1-NICD mutants (B,C,D and B′C′,D,) include weaker MYO6 expression, lack of the normal flask-like shape, more basally positioned nulcei, and nuclear P27KIP1 expression normally only observed in supporting cells at this time. Scale bar in D = 100 microns for A–D, and in D′ = 25 microns for A′–D′.</p