ABSTRACT
OBJECTIVE: Over 5% of the world's population suffers from disabling hearing loss. Stem cell homing in target tissue is an important aspect of cell-based therapy, which its augmentation increases cell therapy efficiency. Deferoxamine (DFO) can induce the Akt activation, and phosphorylation status of AKT (p-AKT) upregulates CXC chemokine receptor-4 (CXCR4) expression. We examined whether DFO can enhance mesenchymal stem cells (MSCs) homing in noise-induced damaged cochlea by PI3K/AKT dependent mechanism. MATERIALS AND METHODS: Mesenchymal stem cells were treated with DFO. AKT, p-AKT protein and hypoxia inducible factor 1- α (HIF-1α) and CXCR4 gene and protein expression was evaluated by RT- PCR and Western blot analysis. For in vivo assay, rats were assigned to control, sham, noise exposure groups without any treatment or receiving normal, DFO-treated and DFO +LY294002 (The PI3K inhibitor)-treated MSCs. Following chronic exposure to 115 dB white noise, MSCs were injected into the rat cochlea through the round window. Number of Hoechst- labelled cells was determined in the endolymph after 24 hours. RESULTS: Deferoxamine increased P-AKT, HIF-1α and CXCR4 expression in MSCs compared to non-treated cells. DFO pre-conditioning significantly increased the homing ability of MSCs into injured ear compared to normal MSCs. These effects of DFO were blocked by LY294002. CONCLUSIONS: Pre-conditioning of MSCs by DFO before transplantation can improve stem cell homing in the damaged cochlea through PI3K/AKT pathway activation.
Subject(s)
Cochlea , Deferoxamine/pharmacology , Mesenchymal Stem Cells/metabolism , Noise/adverse effects , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/biosynthesis , Signal Transduction/drug effects , Animals , Cochlea/injuries , Cochlea/metabolism , Cochlea/pathology , Gene Expression Regulation/drug effects , Hypoxia-Inducible Factor 1, alpha Subunit/biosynthesis , Male , Mesenchymal Stem Cells/pathology , Rats , Rats, Wistar , Receptors, CXCR4/metabolismABSTRACT
OBJECTIVE: Rheumatoid arthritis is thought to induce conductive hearing loss and/or sensorineural hearing loss. This study evaluated the function of the middle ear and cochlea, and the related factors. METHODS: Pure tone audiometry, speech reception thresholds, speech discrimination scores, tympanometry, acoustic reflexes, and distortion product otoacoustic emissions were assessed in rheumatoid arthritis patients and healthy volunteers. RESULTS: Pure tone audiometry results revealed a higher bone conduction threshold in the rheumatoid arthritis group, but there was no significant difference when evaluated according to the sensorineural hearing loss definition. Distortion product otoacoustic emissions related prevalence of conductive or mixed hearing loss, tympanometry values, acoustic reflexes, and speech discrimination scores were not significantly different between the two groups. Sensorineural hearing loss was significantly more prevalent in patients who used azathioprine, cyclosporine and etanercept. CONCLUSION: Higher bone conduction thresholds in some frequencies were detected in rheumatoid arthritis patients that were not clinically significant. Sensorineural hearing loss is significantly more prevalent in refractory rheumatoid arthritis patients.
Subject(s)
Arthritis, Rheumatoid/complications , Cochlea/physiopathology , Ear, Middle/physiopathology , Hearing Loss, Sensorineural/diagnosis , Acoustic Impedance Tests , Adult , Arthritis, Rheumatoid/drug therapy , Arthritis, Rheumatoid/physiopathology , Audiometry, Pure-Tone , Azathioprine/adverse effects , Cyclosporine/adverse effects , Etanercept/adverse effects , Female , Hearing Loss, Sensorineural/etiology , Humans , Male , Middle Aged , Prospective StudiesABSTRACT
OBJECTIVE: To evaluate the relationship between conductive hearing loss and maxillary constriction. METHOD: A total of 120 people, aged from 7 to 40 years, who were referred to an audiologist when taking out health insurance or for school pre-registration check-up, were selected for this study. A total of 60 participants who had hearing threshold levels greater than 15 dB in both ears were chosen as the conductive hearing loss group. The remaining 60, with normal hearing thresholds of less than 15 dB, were used as the control group. All participants were referred to an orthodontic clinic. Participants who had a posterior crossbite and high palatal vault were considered to suffer from maxillary constriction. RESULTS: There were no significant differences between the sex ratios and mean ages of the groups. However, participants with conductive hearing loss were 3.5 times more likely than controls to suffer from maxillary constriction. CONCLUSION: Patients who suffer from conductive hearing loss are likely to show a maxillary abnormality when examined by an orthodontist.
