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Kentala E, Wilson C, Pyykkö I, Varpa K, Stephens D. Positive experiences associated with tinnitus and balance problems. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/16513860801959639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Pyykkö I, Toppila E, Zou J, Kentala E. Individual susceptibility to noise-induced hearing loss. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/16513860601175998] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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103
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104
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Kaasinen S, Pyykkö I, Koskiniemi ML, Vaheri A. Culturing of Acoustic Neuroma—Methodological Aspects. Acta Otolaryngol 2009. [DOI: 10.3109/00016489509125180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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107
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Pyykkö I, Magnusson I, Matsuoka M, Ito S, Hinoki M. On the Optokinetic Mechanisms of Peripheral Retinal Type. Acta Otolaryngol 2009. [DOI: 10.3109/00016488209108529] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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108
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Pyykkö I, Dahlen AI, Schalén L, Hindfelt B. Eye Movements in Patients with Speech Dyspraxia. Acta Otolaryngol 2009. [DOI: 10.3109/00016488409107589] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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109
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Schalén L, Pyykkö I, Henriksson NG, Wennmo C. Slow Eye Movements in Patients with Neurological Disorders. Acta Otolaryngol 2009. [DOI: 10.3109/00016488209108528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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110
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Viljanen A, Kaprio J, Pyykkö I, Sorri M, Kauppinen M, Koskenvuo M, Rantanen T. Genetic and environmental influences on hearing at different frequencies separately for the better and worse hearing ear in older women. Int J Audiol 2009; 46:772-9. [DOI: 10.1080/14992020701581422] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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111
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Keisala T, Minasyan A, Lou YR, Zou J, Kalueff AV, Pyykkö I, Tuohimaa P. Premature aging in vitamin D receptor mutant mice. J Steroid Biochem Mol Biol 2009; 115:91-7. [PMID: 19500727 DOI: 10.1016/j.jsbmb.2009.03.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 03/20/2009] [Accepted: 03/20/2009] [Indexed: 12/16/2022]
Abstract
Hypervitaminosis vitamin D(3) has been recently implicated in premature aging through the regulation of 1alpha hydroxylase expression by klotho and fibroblast growth factor-23 (Fgf-23). Here we examined whether the lack of hormonal function of vitamin D(3) in mice is linked to aging phenomena. For this, we used vitamin D(3) receptor (VDR) "Tokyo" knockout (KO) mice (fed with a special rescue diet) and analyzed their growth, skin and cerebellar morphology, as well as overall motor performance. We also studied the expression of aging-related genes, such as Fgf-23, nuclear factor kappaB (NF-kappaB), p53, insulin like growth factor 1 (IGF1) and IGF1 receptor (IGF1R), in liver, as well as klotho in liver, kidney and prostate tissues. Overall, VDR KO mice showed several aging related phenotypes, including poorer survival, early alopecia, thickened skin, enlarged sebaceous glands and development of epidermal cysts. There was no difference either in the structure of cerebellum or in the number of Purkinje cells. Unlike the wildtype controls, VDR KO mice lose their ability to swim after 6 months of age. Expression of all the genes was lower in old VDR KO mice, but only NF-kappaB, Fgf-23, p53 and IGF1R were significantly lower. Since the phenotype of aged VDR knockout mice is similar to mouse models with hypervitaminosis D(3), our study suggests that VDR genetic ablation promotes premature aging in mice, and that vitamin D(3) homeostasis regulates physiological aging.
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Minasyan A, Keisala T, Zou J, Zhang Y, Toppila E, Syvälä H, Lou YR, Kalueff AV, Pyykkö I, Tuohimaa P. Vestibular dysfunction in vitamin D receptor mutant mice. J Steroid Biochem Mol Biol 2009; 114:161-6. [PMID: 19429446 DOI: 10.1016/j.jsbmb.2009.01.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 01/26/2009] [Accepted: 01/28/2009] [Indexed: 12/16/2022]
Abstract
The vitamin D endocrine system is essential for calcium and bone homeostasis. Vitamin D deficits are associated with muscle weakness and osteoporosis, whereas vitamin D supplementation may improve muscle function, body sway and frequency of falls, growth and mineral homeostasis of bones. The loss of muscle strength and mass, as well as deficits in bone formation, lead to poor balance. Poor balance is one of the main causes of falls, and may lead to dangerous injuries. Here we examine balance functions in vitamin D receptor deficient (VDR-/-) mice, an animal model of vitamin D-dependent rickets type II, and in 1alpha-hydroxylase deficient (1alpha-OHase-/-) mice, an animal model of pseudovitamin D-deficiency rickets. Recently developed methods (tilting box, rotating tube test), swim test, and modified accelerating rotarod protocol were used to examine whether the absence of functional VDR, or the lack of a key vitamin D-activating enzyme, could lead to mouse vestibular dysfunctions. Overall, VDR-/- mice, but not 1alpha-OHase-/- mice, showed shorter latency to fall from the rotarod, smaller fall angle in the tilting box test, and aberrant poor swimming. These data suggest that VDR deficiency in mice is associated with decreased balance function, and may be relevant to poorer balance/posture control in humans with low levels of vitamin D.
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Friedman RA, Van Laer L, Huentelman MJ, Sheth SS, Van Eyken E, Corneveaux JJ, Tembe WD, Halperin RF, Thorburn AQ, Thys S, Bonneux S, Fransen E, Huyghe J, Pyykkö I, Cremers CWRJ, Kremer H, Dhooge I, Stephens D, Orzan E, Pfister M, Bille M, Parving A, Sorri M, Van de Heyning PH, Makmura L, Ohmen JD, Linthicum FH, Fayad JN, Pearson JV, Craig DW, Stephan DA, Van Camp G. GRM7 variants confer susceptibility to age-related hearing impairment. Hum Mol Genet 2009; 18:785-96. [PMID: 19047183 PMCID: PMC2638831 DOI: 10.1093/hmg/ddn402] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 11/20/2008] [Indexed: 01/22/2023] Open
Abstract
Age-related hearing impairment (ARHI), or presbycusis, is the most prevalent sensory impairment in the elderly. ARHI is a complex disease caused by an interaction between environmental and genetic factors. Here we describe the results of the first whole genome association study for ARHI. The study was performed using 846 cases and 846 controls selected from 3434 individuals collected by eight centers in six European countries. DNA pools for cases and controls were allelotyped on the Affymetrix 500K GeneChip for each center separately. The 252 top-ranked single nucleotide polymorphisms (SNPs) identified in a non-Finnish European sample group (1332 samples) and the 177 top-ranked SNPs from a Finnish sample group (360 samples) were confirmed using individual genotyping. Subsequently, the 23 most interesting SNPs were individually genotyped in an independent European replication group (138 samples). This resulted in the identification of a highly significant and replicated SNP located in GRM7, the gene encoding metabotropic glutamate receptor type 7. Also in the Finnish sample group, two GRM7 SNPs were significant, albeit in a different region of the gene. As the Finnish are genetically distinct from the rest of the European population, this may be due to allelic heterogeneity. We performed histochemical studies in human and mouse and showed that mGluR7 is expressed in hair cells and in spiral ganglion cells of the inner ear. Together these data indicate that common alleles of GRM7 contribute to an individual's risk of developing ARHI, possibly through a mechanism of altered susceptibility to glutamate excitotoxicity.
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Zou J, Poe D, Bjelke B, Pyykkö I. Visualization of inner ear disorders with MRI in vivo: from animal models to human application. Acta Otolaryngol 2009:22-31. [PMID: 19221903 DOI: 10.1080/00016480902729850] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CONCLUSION The inner ear membranous permeability and leakiness and endolymphatic hydrops can be visualized using gadolinium-enhanced MRI in both rodents and man. Intratympanic administration of contrast agent gives greater perilymphatic loading of gadolinium. OBJECTIVES Visualization of different types of inner ear dysfunction in MRI with intravenous or intratympanic administration of contrast agent. MATERIALS AND METHODS In the animal study, gadolinium was administered intravenously or intratympanically and imaged with 4.7 T MRI. In man, gadolinium was delivered intratympanically and studied with 1.5 T or 3 T MRI. RESULTS In the animals, intravenous delivery of gadolinium demonstrated uptake in the perilymph of normal inner ears. The cochlear modiolus appeared to be a critical site for the secretion of perilymph and the location of fluid communication between the perilymphatic scalae. Intense noise exposure and immune reaction caused cochlear injury and accelerated gadolinium passage through the blood-perilymph and blood-endolymph barriers. In man, perilymphatic uptake of gadolinium was only observed in the impaired inner ear when administered intravenously. However, the signal-to-noise ratio of images was improved when gadolinium was delivered intratympanically. MRI demonstrated endolymphatic hydrops in both animal models and patients with Meniere's disease.
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Nakashima T, Naganawa S, Pyykkö I, Gibson WP, Sone M, Nakata S, Teranishi M. Grading of endolymphatic hydrops using magnetic resonance imaging. Acta Otolaryngol 2009:5-8. [PMID: 19221900 DOI: 10.1080/00016480902729827] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
CONCLUSION Grading of endolymphatic hydrops in the vestibule and the cochlea using magnetic resonance imaging (MRI) is proposed (2008 Nagoya scale). OBJECTIVE To standardize the evaluation of endolymphatic hydrops in both the vestibule and the cochlea using MRI. PATIENTS AND METHODS The endolymphatic space was evaluated after intratympanic gadolinium injection using three-dimensional fluid attenuated (3D-FLAIR) MRI and three-dimensional real inversion recovery (3D-real IR) MRI. RESULTS A simple three-stage grading system was acceptable for hydrops in both the vestibule and the cochlea: none, mild, and significant. In the vestibule, the grading was determined by the ratio of the area of endolymphatic space to the vestibular fluid space (sum of the endolymphatic and perilymphatic spaces). Patients with no hydrops have a ratio of one-third or less, those with mild hydrops have between one-third and a half, and those with significant hydrops have a ratio of more than 50%. In the cochlea, patients classified as having no hydrops show no displacement of Reissner's membrane; those with mild hydrops show displacement of Reissner's membrane but the area of the endolymphatic space does not exceed the area of the scala vestibuli; and in those with significant hydrops the area of the endolymphatic space exceeds the area of the scala vestibuli.
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116
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Viljanen A, Kaprio J, Pyykkö I, Sorri M, Pajala S, Kauppinen M, Koskenvuo M, Rantanen T. Hearing as a predictor of falls and postural balance in older female twins. J Gerontol A Biol Sci Med Sci 2009; 64:312-7. [PMID: 19182227 DOI: 10.1093/gerona/gln015] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The purpose of the present study was to examine, first, whether hearing acuity predicts falls and whether the potential association is explained by postural balance and, second, to examine whether shared genetic or environmental effects underlie these associations. METHODS Hearing was measured using a clinical audiometer as a part of the Finnish Twin Study on Aging in 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Postural balance was indicated as a center of pressure (COP) movement in semi-tandem stance, and participants filled in a fall-calendar daily for an average of 345 days after the baseline. RESULTS Mean hearing acuity (better ear hearing threshold level at 0.5-4 kHz) was 21 dB (standard deviation [SD] 12). Means of the COP velocity moment for the best to the poorest hearing quartiles increased linearly from 40.7 mm(2)/s (SD 24.4) to 52.8 mm(2)/s (SD 32.0) (p value for the trend = .003). Altogether 199 participants reported 437 falls. Age-adjusted incidence rate ratios (IRRs) for falls, with the best hearing quartile as a reference, were 1.2 (95% confidence interval [CI] = 0.4-3.8) in the second, 4.1 (95% CI = 1.1-15.6) in the third, and 3.4 (95% CI = 1.0-11.4) in the poorest hearing quartiles. Adjustment for COP velocity moment decreased IRRs markedly. Twin analyses showed that the association between hearing acuity and postural balance was not explained by genetic factors in common for these traits. CONCLUSION People with poor hearing acuity have a higher risk for falls, which is partially explained by their poorer postural control. Auditory information about environment may be important for safe mobility.
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Zou J, Zhang Y, Yin S, Wu H, Pyykkö I. Mitochondrial dysfunction disrupts trafficking of Kir4.1 in spiral ganglion satellite cells. J Neurosci Res 2009; 87:141-9. [DOI: 10.1002/jnr.21842] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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118
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Zou J, Zhang Y, Zhang W, Ranjan S, Sood R, Mikhailov A, Kinnunen P, Pyykkö I. Preclinical Nanomedicine: Internalization of liposome nanoparticles functionalized with TrkB ligand in rat cochlear cell populations. EUROPEAN JOURNAL OF NANOMEDICINE 2009. [DOI: 10.1515/ejnm.2009.2.2.7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Rasku J, Juhola M, Pyykkö I, Toppila E, Varpa K. The effect of removing the force feedback during the quiet stance. Stud Health Technol Inform 2009; 150:620-624. [PMID: 19745386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The human postural control system is complex and it combines information from different sources. The most important information comes from vestibular, visual and proprioceptive senses. We studied the effects of removing the visual and proprioceptive information simultaneously. The force feedback from the ground was removed with vibrators attached on the musculus soleus of both calves. By using features of force platform signals, when the vibrators were on, the lengths of the swaying paths were four times the lengths when the vibrators were off. Our results show that it is possible to separate the effects of the visual and proprioceptive senses from that of vestibular sense, which is very useful for investigations of balance problems in otoneurology. This supports our future aim to classify between healthy subjects and different otoneurological patients with signal analysis and pattern recognition methods to be used for force platform signals.
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Poe D, Zou J, Zhang W, Qin J, Ramadan UA, Fornara A, Muhammed M, Pyykkö I. preclinical nanomedicine: MRI of the Cochlea with Superparamagnetic Iron oxide nanoparticles Compared to Gadolinium Chelate Contrast Agents in a Rat Model. EUROPEAN JOURNAL OF NANOMEDICINE 2009. [DOI: 10.1515/ejnm.2009.2.2.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Zou J, Saulnier P, Perrier T, Zhang Y, Manninen T, Toppila E, Pyykkö I. Distribution of lipid nanocapsules in different cochlear cell populations after round window membrane permeation. J Biomed Mater Res B Appl Biomater 2008; 87:10-8. [PMID: 18437698 DOI: 10.1002/jbm.b.31058] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hearing loss is a major public health problem, and its treatment with traditional therapy strategies is often unsuccessful due to limited drug access deep in the temporal bone. Multifunctional nanoparticles that are targeted to specified cell populations, biodegradable, traceable in vivo, and equipped with controlled drug/gene release may resolve this problem. We developed lipid core nanocapsules (LNCs) with sizes below 50 nm. The aim of the present study is to evaluate the ability of the LNCs to pass through the round window membrane and reach inner ear targets. FITC was incorporated as a tag for the LNCs and Nile Red was encapsulated inside the oily core to assess the integrity of the LNCs. The capability of LNCs to pass through the round window membrane and the distribution of the LNCs inside the inner ear were evaluated in rats via confocal microscopy in combination with image analysis using ImageJ. After round window membrane administration, LNCs reached the spiral ganglion cells, nerve fibers, and spiral ligament fibrocytes within 30 min. The paracellular pathway was the main approach for LNC penetration of the round window membrane. LNCs can also reach the vestibule, middle ear mucosa, and the adjacent artery. Nuclear localization was detected in the spiral ganglion, though infrequently. These results suggest that LNCs are potential vectors for drug delivery into the spiral ganglion cells, nerve fibers, hair cells, and spiral ligament.
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Huyghe JR, Van Laer L, Hendrickx JJ, Fransen E, Demeester K, Topsakal V, Kunst S, Manninen M, Jensen M, Bonaconsa A, Mazzoli M, Baur M, Hannula S, Mäki-Torkko E, Espeso A, Van Eyken E, Flaquer A, Becker C, Stephens D, Sorri M, Orzan E, Bille M, Parving A, Pyykkö I, Cremers CW, Kremer H, Van de Heyning PH, Wienker TF, Nürnberg P, Pfister M, Van Camp G. Genome-wide SNP-based linkage scan identifies a locus on 8q24 for an age-related hearing impairment trait. Am J Hum Genet 2008; 83:401-7. [PMID: 18760390 DOI: 10.1016/j.ajhg.2008.08.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/07/2008] [Accepted: 08/07/2008] [Indexed: 10/21/2022] Open
Abstract
Age-related hearing impairment (ARHI), or presbycusis, is a very common multifactorial disorder. Despite the knowledge that genetics play an important role in the etiology of human ARHI as revealed by heritability studies, to date, its precise genetic determinants remain elusive. Here we report the results of a cross-sectional family-based genetic study employing audiometric data. By using principal component analysis, we were able to reduce the dimensionality of this multivariate phenotype while capturing most of the variation and retaining biologically important features of the audiograms. We conducted a genome-wide association as well as a linkage scan with high-density SNP microarrays. Because of the presence of genetic population substructure, association testing was stratified after which evidence was combined by meta-analysis. No association signals reaching genome-wide significance were detected. Linkage analysis identified a linkage peak on 8q24.13-q24.22 for a trait correlated to audiogram shape. The signal reached genome-wide significance, as assessed by simulations. This finding represents the first locus for an ARHI trait.
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Fransen E, Topsakal V, Hendrickx JJ, Van Laer L, Huyghe JR, Van Eyken E, Lemkens N, Hannula S, Mäki-Torkko E, Jensen M, Demeester K, Tropitzsch A, Bonaconsa A, Mazzoli M, Espeso A, Verbruggen K, Huyghe J, Huygen PLM, Kunst S, Manninen M, Diaz-Lacava A, Steffens M, Wienker TF, Pyykkö I, Cremers CWRJ, Kremer H, Dhooge I, Stephens D, Orzan E, Pfister M, Bille M, Parving A, Sorri M, Van de Heyning P, Van Camp G. Occupational noise, smoking, and a high body mass index are risk factors for age-related hearing impairment and moderate alcohol consumption is protective: a European population-based multicenter study. J Assoc Res Otolaryngol 2008; 9:264-76; discussion 261-3. [PMID: 18543032 PMCID: PMC2492985 DOI: 10.1007/s10162-008-0123-1] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Accepted: 04/21/2008] [Indexed: 11/27/2022] Open
Abstract
A multicenter study was set up to elucidate the environmental and medical risk factors contributing to age-related hearing impairment (ARHI). Nine subsamples, collected by nine audiological centers across Europe, added up to a total of 4,083 subjects between 53 and 67 years. Audiometric data (pure-tone average [PTA]) were collected and the participants filled out a questionnaire on environmental risk factors and medical history. People with a history of disease that could affect hearing were excluded. PTAs were adjusted for age and sex and tested for association with exposure to risk factors. Noise exposure was associated with a significant loss of hearing at high sound frequencies (>1 kHz). Smoking significantly increased high-frequency hearing loss, and the effect was dose-dependent. The effect of smoking remained significant when accounting for cardiovascular disease events. Taller people had better hearing on average with a more pronounced effect at low sound frequencies (<2 kHz). A high body mass index (BMI) correlated with hearing loss across the frequency range tested. Moderate alcohol consumption was inversely correlated with hearing loss. Significant associations were found in the high as well as in the low frequencies. The results suggest that a healthy lifestyle can protect against age-related hearing impairment.
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Zou J, Minasyan A, Keisala T, Zhang Y, Wang JH, Lou YR, Kalueff A, Pyykkö I, Tuohimaa P. Progressive hearing loss in mice with a mutated vitamin D receptor gene. Audiol Neurootol 2008; 13:219-30. [PMID: 18259074 DOI: 10.1159/000115431] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 10/19/2007] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Both hypo- and hypervitaminosis D can cause sensorineural hearing loss, and aural symptoms due to vitamin D insufficiency are especially common during gravidity. Hormonal forms of vitamin D regulate transcription by binding with the high-affinity vitamin D receptor (VDR). OBJECTIVE To assess the effects of impaired vitamin D action in VDR knockout (KO) mice on hearing, cochlear morphology, and cochlear gene expression. MATERIALS AND METHODS Eighteen young male and female mice (10 VDR KO and 8 wild type, WT, < or =6 months old), 33 adult male and female mice (16 VDR KO and 17 WT, between 7 and 14 months old), and 11 aged male and female mice (5 VDR KO and 6 WT, > or =15 months old) on 129S1 genetic background were studied. Auditory thresholds were evaluated by auditory brain stem response. Morphological changes were analyzed using plastic embedding and light microscopy. The expression of key genes (known to play a role in the regulation of cochlear function), and caspase 3 activity, were assessed using immunofluorescent confocal microscopy. RESULTS There was a statistically significant difference between the young and the adult groups, and between the adult and aged groups of WT mice. There was also a statistically significant difference between the adult and aged groups in VDR KO mice, and between the young WT group and the young VDR KO group. Spiral ganglion cell loss was observed in the basal turn of adult VDR KO mice, a phenomenon infrequently found in WT mice. Expression of connexin 26, KCNJ10, and transient receptor potential channel vanilloid subfamily 4/6 was not affected by VDR KO-mediated hearing loss. Caspase 3 activation was detected in the spiral ganglion cell and its satellite cells, stria vascularis, spiral ligament fibrocytes, and the organ of Corti in both genotypes. However, the percentage of positive cells and the staining intensity were lower in the VDR KO (compared to the WT) mice. CONCLUSION These data suggest that sensorineural hearing loss progressively developed at an earlier age in VDR KO mice. While the fundamental gene expressions in the cochlea were not influenced by VDR mutation, it resulted in decrease of caspase 3 activation, which may be one of the factors underlying accelerating age-related hearing loss observed in VDR KO mice.
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Pyykkö I, Zou J. Do Viruses Cause Inner Ear Disturbances? ORL J Otorhinolaryngol Relat Spec 2008; 70:32-40; discussion 40-1. [DOI: 10.1159/000111046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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