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Gu Y, Ohgami N, Al Hossain MMA, Tazaki A, Tsuchiyama T, He T, Aoki M, Ahsan N, Akhand AA, Kato M. Decreased hearing levels at frequencies for understanding speech in tannery workers exposed to a high level of trivalent chromium in Bangladesh. CHEMOSPHERE 2022; 306:135571. [PMID: 35798151 DOI: 10.1016/j.chemosphere.2022.135571] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/21/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Hexavalent chromium [Cr(VI)], which has a strong corrosive effect, has been reported to cause perforation of the eardrum. Trivalent chromium [Cr(III)] also has a weak corrosive effect. However, there has been no study on the effects of exposure to Cr, either Cr(VI) or Cr(III), on hearing levels in animals or humans. In this study, the effect of Cr(III) exposure on hearing levels was determined in a human study. Then the reproducibility of the results obtained in the human study and the etiology were investigated in an animal study. The mean levels of total chromium (t-Cr) in hair and toenails from 100 Bangladeshi tannery workers were >20-fold and >360-fold higher, respectively, than those in hair and toenails from 49 Bangladeshi non-tannery workers (office workers). Multivariate analysis revealed decreases of hearing levels (DHLs) at 1 k and 4 k Hz, frequencies that are crucial for understanding language, but not at 8 k and 12 k Hz, in the tannery workers. Since >99.99% of t-Cr in the wastewater that the workers were in direct contact with in the tanneries was Cr(III), the epidemiological results suggest Cr(III)-mediated DHLs in the tannery workers. The results of animal experiments in this study further showed that treatment with eardrops but not intraperitoneal injection with the same amount of Cr(III) that tannery workers might be exposed to resulted in DHL with a damaged eardrum in mice. Previous studies suggested that Cr(III) can directly reach the eardrums of tannery workers via droplets in the air. Cr(III) could also reach the eardrum via picking an ear canal with a finger contaminated with tannery wastewater including Cr(III). Taken together, the results of both human and animal studies suggest the risk of DHLs caused by damage of the eardrum through external exposure to Cr(III) via the ear canal.
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Affiliation(s)
- Yishuo Gu
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan.
| | - Nobutaka Ohgami
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan; Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai, Aichi, Japan.
| | - M M Aeorangajeb Al Hossain
- Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan; Directorate General of Health Services, Ministry of Health and Family Welfare, Government of the People's Republic of Bangladesh, Mohakhali, Dhaka, 1212, Bangladesh.
| | - Akira Tazaki
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan.
| | - Tomoyuki Tsuchiyama
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan.
| | - Tingchao He
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan.
| | - Masayo Aoki
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan.
| | - Nazmul Ahsan
- Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan; Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, 1000, Bangladesh.
| | - Anwarul Azim Akhand
- Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan; Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, 1000, Bangladesh.
| | - Masashi Kato
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan; Voluntary Body for International Healthcare in Universities, Nagoya, Aichi, Japan; Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai, Aichi, Japan.
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Trans-Oval-Window Implants, A New Approach for Drug Delivery to the Inner Ear: Extended Dexamethasone Release From Silicone-based Implants. Otol Neurotol 2016; 36:1572-9. [PMID: 26375981 DOI: 10.1097/mao.0000000000000855] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS The purpose of this study was to develop a new strategy to deliver drugs to the inner ear from dexamethasone (DXM)-loaded silicone implants and to evaluate the distribution of the drug in the cochlea with confocal microscopy. BACKGROUND Systemic drug administration for the treatment of inner ear disorders is tricky because of the blood-cochlear barrier, a difficult anatomical access, the small size of the cochlea, and can cause significant adverse effects. An effective way to overcome these obstacles is to administer drugs locally. METHODS In vitro, the drug release from DXM-loaded silicone-based thin films and tiny implants into artificial perilymph was thoroughly analyzed by high-performance liquid chromatography. In vivo, a silicone implant loaded with 10% DXM and 5% polyethylene glycol 400 was implanted next to the stapes's footplate of gerbils. Delivery of DXM into the inner ear was proved by confocal microscopy imaging of the whole cochlea and the organ of Corti. RESULTS The study showed a continuous and prolonged release during 90 days in vitro. This was confirmed by confocal microscopy that allowed detection of DXM by fluorescence labeling in the cell body of the hair cells for at least 30 days. Interestingly, fluorescence was already observed after 20 minutes of implantation, reached a climax at day 7, and could still be detected 30 days after implantation. CONCLUSIONS Thus, we developed a new device for local corticosteroids delivery into the oval window with an extended drug release of DXM to the inner ear.
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Benedetti G, Fokkelman M, Yan K, Fredriksson L, Herpers B, Meerman J, van de Water B, de Graauw M. The nuclear factor κB family member RelB facilitates apoptosis of renal epithelial cells caused by cisplatin/tumor necrosis factor α synergy by suppressing an epithelial to mesenchymal transition-like phenotypic switch. Mol Pharmacol 2013; 84:128-38. [PMID: 23625948 DOI: 10.1124/mol.112.084053] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cis-diamminedichloroplatinum(II) (cisplatin)-induced renal proximal tubular apoptosis is known to be preceded by actin cytoskeleton reorganization, in conjunction with disruption of cell-matrix and cell-cell adhesion. In the present study, we show that the proinflammatory cytokine tumor necrosis factor α (TNF-α) aggravated these cisplatin-induced F-actin and cell adhesion changes, which was associated with enhanced cisplatin-induced apoptosis of immortalized proximal tubular epithelial cells. TNF-α-induced RelB expression and lentiviral small hairpin RNA (shRNA)-mediated knockdown of RelB, but not other nuclear factor κB members, abrogated the synergistic apoptosis observed with cisplatin/TNF-α treatment to the level of cisplatin-induced apoptosis. This protective effect was associated with increased stress fiber formation, cell-matrix, and cell-cell adhesion in the shRNARelB (shRelB) cells during cisplatin/TNF-α treatment, mimicking an epithelial-to-mesenchymal phenotypic switch. Indeed, gene array analysis revealed that knockdown of RelB was associated with upregulation of several actin regulatory genes, including Snai2 and the Rho GTPase proteins Rhophilin and Rho guanine nucleotide exchange factor 3 (ARHGEF3). Pharmacological inhibition of Rho kinase signaling re-established the synergistic apoptosis induced by combined cisplatin/TNF-α treatment of shRelB cells. In conclusion, our study shows for the first time that RelB is required for the cisplatin/TNF-α-induced cytoskeletal reorganization and apoptosis in renal cells by controlling a Rho kinase-dependent signaling network.
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Affiliation(s)
- Giulia Benedetti
- Division of Toxicology, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratory, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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