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1.
Healthc Inform Res ; 29(4): 315-322, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37964453

ABSTRACT

OBJECTIVES: Artificial intelligence (AI) technologies are developing very rapidly in the medical field, but have yet to be actively used in actual clinical settings. Ensuring reliability is essential to disseminating technologies, necessitating a wide range of research and subsequent social consensus on requirements for trustworthy AI. METHODS: This review divided the requirements for trustworthy medical AI into explainability, fairness, privacy protection, and robustness, investigated research trends in the literature on AI in healthcare, and explored the criteria for trustworthy AI in the medical field. RESULTS: Explainability provides a basis for determining whether healthcare providers would refer to the output of an AI model, which requires the further development of explainable AI technology, evaluation methods, and user interfaces. For AI fairness, the primary task is to identify evaluation metrics optimized for the medical field. As for privacy and robustness, further development of technologies is needed, especially in defending training data or AI algorithms against adversarial attacks. CONCLUSIONS: In the future, detailed standards need to be established according to the issues that medical AI would solve or the clinical field where medical AI would be used. Furthermore, these criteria should be reflected in AI-related regulations, such as AI development guidelines and approval processes for medical devices.

2.
Hum Mutat ; 43(12): 2205-2221, 2022 12.
Article in English | MEDLINE | ID: mdl-36349709

ABSTRACT

Some spontaneous germline gain-of-function mutations promote spermatogonial stem cell clonal expansion and disproportionate variant sperm production leading to unexpectedly high transmission rates for some human genetic conditions. To measure the frequency and spatial distribution of de novo mutations we divided three testes into 192 pieces each and used error-corrected deep-sequencing on each piece. We focused on PTPN11 (HGNC:9644) Exon 3 that contains 30 different PTPN11 Noonan syndrome (NS) mutation sites. We found 14 of these variants formed clusters among the testes; one testis had 11 different variant clusters. The mutation frequencies of these different clusters were not correlated with their case-recurrence rates nor were case recurrence rates of PTPN11 variants correlated with their tyrosine phosphatase levels thereby confusing PTPN11's role in germline clonal expansion. Six of the PTPN11 exon 3 de novo variants associated with somatic mutation-induced sporadic cancers (but not NS) also formed testis clusters. Further, three of these six variants were observed among fetuses that underwent prenatal ultrasound screening for NS-like features. Mathematical modeling showed that germline selection can explain both the mutation clusters and the high incidence of NS (1/1000-1/2500).


Subject(s)
Neoplasms , Noonan Syndrome , Pregnancy , Female , Humans , Male , Noonan Syndrome/genetics , Birth Rate , Semen , Exons , Mutation , Neoplasms/genetics , Protein Tyrosine Phosphatase, Non-Receptor Type 11/genetics
3.
J Nurs Scholarsh ; 54(5): 569-577, 2022 09.
Article in English | MEDLINE | ID: mdl-35174636

ABSTRACT

AIMS: This study aimed to investigate the effectiveness and understand the process of a nurse-led social media intervention for health behavior and glucose control for diabetes self-management among patients with type 2 diabetes mellitus. DESIGN: This study had an explanatory sequential mixed methods design, with a randomized controlled trial and qualitative interviews. METHODS: A total of 89 patients diagnosed with type 2 diabetes mellitus were randomly assigned to an intervention or a control group. Patients in the intervention group were invited to join the closed nurse-led social media platform that included diabetes information, action planning, unmoderated chat, and questions and answers. The outcomes of diabetes self-care behavior, hemoglobin A1c (HbA1c) percentage, fasting blood sugar level (FBS), systolic and diastolic blood pressure, and triglyceride (TG) and total cholesterol levels were measured at baseline, 3 months, and 6 months. A linear mixed model was used to analyze the effectiveness of the intervention over time. Qualitative data were collected from interviews with seven patients engaged in the intervention and analyzed using qualitative content analysis. FINDINGS: After 6 months, insulin users who were provided with the social media intervention had significantly lower FBS and TG levels than those with usual care (135.80 ± 12.37 vs. 175.82 ± 15.34 mg/dL, p = 0.049; 206.85 ± 38.26 vs. 387.50 ± 56.19 mg/dL, p = 0.013; respectively). Although a similar rate of decrease in the HbA1c level over time was observed among insulin and noninsulin users after the social media intervention, this decrease was significantly greater among noninsulin users at 3 and 6 months compared with the control group (6.38 ± 0.34 vs. 7.25 ± 0.24, p = 0.040; 6.31 ± 0.37 vs. 7.28 ± 0.26, p = 0.036; respectively). Interview with seven patients who engaged in the intervention revealed that their engagement in the intervention was primarily determined by their acceptance of the role of managing their diabetes. Being engaged in the intervention, patients benefited from information sharing and interactive support to motivate their self-care, nurses' professional advice to modify their behaviors, and action planning to make progress toward behavioral change. CONCLUSIONS: The positive outcomes of the nurse-led social media intervention indicate that the social media platform is an effective strategy to implement diabetes self-management in clinical nursing practice. CLINICAL RELEVANCE: The social media intervention would be successfully implemented by nurses to facilitate patients accepting their role in diabetes management and employing key services for diabetes information, support, professional advice, and action planning.


Subject(s)
Diabetes Mellitus, Type 2 , Insulins , Social Media , Diabetes Mellitus, Type 2/therapy , Glycated Hemoglobin/analysis , Humans , Nurse's Role
4.
Polymers (Basel) ; 15(1)2022 Dec 29.
Article in English | MEDLINE | ID: mdl-36616511

ABSTRACT

Infection associated with biomedical implants remains the main cause of failure, leading to reoperation after orthopedic surgery. Orthopedic infections are characterized by microbial biofilm formation on the implant surface, which makes it challenging to diagnose and treat. One potential method to prevent and treat such complications is to deliver a sufficient dose of antibiotics at the onset of infection. This strategy can be realized by coating the implant with thermoregulatory polymers and triggering the release of antibiotics during the acute phase of infection. We developed a multi-layered temperature-responsive polymer brush (MLTRPB) coating that can release antibiotics once the temperature reaches a lower critical solution temperature (LCST). The coating system was developed using copolymers composed of diethylene glycol methyl ether methacrylate and 2-hydroxyethyl methacrylate by alternatively fabricating monomers layer by layer on the titanium surface. LCST was set to the temperature of 38-40 °C, a local temperature that can be reached during infection. The antibiotic elution characteristics were investigated, and the antimicrobial efficacy was tested against S. aureus species (Xen29 ATCC 29 213) using one to four layers of MLTRPB. Both in vitro and in vivo assessments demonstrated preventive effects when more than four layers of the coating were applied, ensuring promising antibacterial effects of the MLTRPB coating.

5.
Oncotarget ; 8(7): 11094-11104, 2017 Feb 14.
Article in English | MEDLINE | ID: mdl-28052004

ABSTRACT

Based on our previous studies, differential analysis of N-glycan expression bound on serum haptoglobin reveals the quantitative variation on gastric cancer patients. In this prospective case-control study, we explore the clinically relevant glycan markers for gastric cancer diagnosis. Serum samples were collected from patients with gastric cancer (n = 44) and healthy control (n = 44). N-glycans alteration was monitored by intact analysis of Hp using liquid chromatography-mass spectrometry followed by immunoaffinity purification with the serum samples. Intensity and frequency markers were defined depending on the mass spectrometry data analysis. Multiple markers were found with high diagnostic efficacy. As intensity markers (I-marker), six markers were discovered with the AUC > 0.8. The high efficiency markers exhibited AUC of 0.93 with a specificity of 86% when the sensitivity was set to 95%. We additionally established frequency marker (f-marker) panels based on the tendency of high N-glycan expression. The AUC to conclude patients and control group were 0.82 and 0.79, respectively. This study suggested that N-glycan variation of serum haptoglobin were associated with patients with gastric cancer and might be a promising marker for the cancer screening.


Subject(s)
Biomarkers, Tumor/metabolism , Haptoglobins/metabolism , Polysaccharides/metabolism , Stomach Neoplasms/metabolism , Adult , Aged , Biomarkers, Tumor/blood , Case-Control Studies , Chromatography, Liquid , Early Detection of Cancer/methods , Female , Glycosylation , Humans , Male , Mass Spectrometry , Middle Aged , Prospective Studies , Reproducibility of Results , Sensitivity and Specificity , Stomach Neoplasms/blood , Stomach Neoplasms/diagnosis
6.
Int J Pharm ; 488(1-2): 165-73, 2015 Jul 05.
Article in English | MEDLINE | ID: mdl-25907511

ABSTRACT

A series of ternary complex was designed to deliver psiRNA-bcl2 and (KLA)4 peptide into cancer cells for cancer therapy. The delivered psiRNA-bcl2 induced gene-silencing in a nucleus of cancer cells, while (KLA)4 peptide inhibited cancer growth via mitochondrial apoptosis, indicating that the ternary complexes exerted very strong synergistic effects on cancer growth suppression by acting on psiRNA-bcl2 and (KLA)4 peptide simultaneously. The ternary complexes having a targeting-ligand, transferrin (TfP), were found to be especially effective at binding to the TfP receptor rich cancer cells, HCT119. The plasmid DNA (pDNA) in ternary complexes was completely condensed at various content of LMWSC-PEG-TfP (32-64 times more than pDNA) and released into cells. pDNA in the complexes was protected from DNase present on the exterior of cells. The size (165-248 nm) of ternary complexes with LMWSC-PEG-TfP was increased, but surface charges (3-4.5 mV) were decreased. These results likely occurred because the free amine-group of LMWSC decreased in response to conjugated transferrin. Moreover, transfected ternary complexes with LMWSC-PEG-TfP were not expressed in the normal cells (HEK293), but were over expressed in HCT119 cells. These findings indicate that the ternary complexes can be specifically targeted to HCT119 cancer cells. The useful complexes for gene and peptide delivery had high anticancer activities via a synergistic effect due to co-operative action of psiRNA and (KLA)4 peptide in HCT119 cells.


Subject(s)
Chitosan/chemistry , Genes, bcl-2/physiology , Peptides/metabolism , Ternary Complex Factors/chemistry , Transfection/methods , Transferrin/chemistry , Apoptosis , Cell Line, Tumor , Chemistry, Pharmaceutical , Gene Silencing , Genetic Therapy/methods , Humans , Intercellular Signaling Peptides and Proteins
7.
Carbohydr Polym ; 111: 822-9, 2014 Oct 13.
Article in English | MEDLINE | ID: mdl-25037421

ABSTRACT

A fucoidan extracted from Sargassum fulvellum, was degraded by ultrasound (US) or electron beam (EB) irradiation in the presence of hydrogen peroxide aqueous solution. From the energetic point of view, the most effective method for the fucoidan degradation was found to be EB radiation method in H2O2 with a yield of scission Gs 3.310 × 10(-8)mol/J at the reaction condition of 1.5% hydrogen peroxide and irradiation 2.5 kGy. The degradation took place by the formation of a reactive hydroxyl radical due to the dissociation of H2O2 in the presence of US or EB. The low molecular weight fucoidans (LMWFs) prevented P-selectin binding to Sialyl Lewis X with an IC50 (inhibitory concentration 50) of 20 nM as compared to 400 nM for heparin and 25,000 nM for dextran sulfate. The LMWFs showed no hemolytic activity at concentrations up to 950 µg/ml.


Subject(s)
Polysaccharides/chemistry , Polysaccharides/pharmacology , Sargassum/chemistry , Cell Survival/drug effects , Electrons , Hemolysis/drug effects , Human Umbilical Vein Endothelial Cells , Humans , Hydrogen Peroxide/chemistry , P-Selectin/metabolism , Polysaccharides/isolation & purification , Sonication
8.
Int J Nanomedicine ; 8: 4147-55, 2013.
Article in English | MEDLINE | ID: mdl-24204143

ABSTRACT

This study aimed to develop an oral delivery system using clay-based organic-inorganic hybrid materials to improve the bioavailability of the drug, flurbiprofen, which is poorly soluble in water. 3-aminopropyl functionalized magnesium phyllosilicate (AMP clay) was synthesized by a one-pot direct sol-gel method, and then flurbiprofen (FB) was incorporated into AMP clay (FB-AMP) at different drug/clay ratios. The structural characteristics of AMP and FB-AMP formulation were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. Among tested formulations, FB-AMP(3), dramatically increased the dissolution of FB and achieved rapid and complete drug release within 2 hours. More than 60% of FB was released from FB-AMP(3) after 30 minutes; the drug was completely dissolved in the water within 2 hours. Under the acidic condition (pH 1.2), FB-AMP(3) also increased the dissolution of FB by up to 47.1% within 1 hour, which was three-fold higher than that of untreated FB. Furthermore, following an oral administration of FB-AMP(3) to Sprague-Dawley rats, the peak plasma concentration and area under the plasma concentration-time curve of FB increased two-fold, and the time to reach the peak plasma concentration was shortened compared with that in the untreated FB. This result suggests that the oral drug delivery system using clay-based organic-inorganic hybrid material might be useful to improve the bioavailability of FB.


Subject(s)
Drug Carriers/chemistry , Flurbiprofen/chemistry , Flurbiprofen/pharmacokinetics , Magnesium Silicates/chemistry , Administration, Oral , Animals , Biological Availability , Drug Carriers/administration & dosage , Drug Carriers/pharmacokinetics , Flurbiprofen/administration & dosage , Flurbiprofen/blood , Hydrogen-Ion Concentration , Magnesium Silicates/administration & dosage , Magnesium Silicates/pharmacokinetics , Male , Rats , Rats, Sprague-Dawley , Solubility
9.
J Microbiol ; 50(5): 785-91, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23124746

ABSTRACT

Triclosan is a widely used biocide effective against different microorganisms. At bactericidal concentrations, triclosan appears to affect multiple targets, while at bacteriostatic concentrations, triclosan targets FabI. The site-specific antibiotic-like mode-of-action and a widespread use of triclosan in household products claimed to possibly induce cross-resistance to other antibiotics. Thus, we set out to define more systematically the genes conferring resistance to triclosan; A genomic library of Escherichia coli strain W3110 was constructed and enriched in a selective medium containing a lethal concentration of triclosan. The genes enabling growth in the presence of triclosan were identified by using a DNA microarray and confirmed consequently by ASKA clones overexpressing the selected 62 candidate genes. Among these, forty-seven genes were further confirmed to enhance the resistance to triclosan; these genes, including the FabI target, were involved in inner or outer membrane synthesis, cell-surface material synthesis, transcriptional activation, sugar phosphotransferase (PTS) systems, various transporter systems, cell division, and ATPase and reductase/dehydrogenase reactions. In particular, overexpression of pgsA, rcsA, or gapC conferred to E. coli cells a similar level of triclosan resistance induced by fabI overexpression. These results indicate that triclosan may have multiple targets other than well-known FabI and that there are several undefined novel mechanisms for the resistance development to triclosan, thus probably inducing cross antibiotic resistance.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Escherichia coli Proteins/genetics , Escherichia coli/drug effects , Genome, Bacterial , Triclosan/pharmacology , Escherichia coli/genetics , Escherichia coli/metabolism , Escherichia coli Proteins/metabolism
10.
PLoS Genet ; 8(2): e1002420, 2012.
Article in English | MEDLINE | ID: mdl-22359510

ABSTRACT

Multiple endocrine neoplasia type 2B (MEN2B) is a highly aggressive thyroid cancer syndrome. Since almost all sporadic cases are caused by the same nucleotide substitution in the RET proto-oncogene, the calculated disease incidence is 100-200 times greater than would be expected based on the genome average mutation frequency. In order to determine whether this increased incidence is due to an elevated mutation rate at this position (true mutation hot spot) or a selective advantage conferred on mutated spermatogonial stem cells, we studied the spatial distribution of the mutation in 14 human testes. In donors aged 36-68, mutations were clustered with small regions of each testis having mutation frequencies several orders of magnitude greater than the rest of the testis. In donors aged 19-23 mutations were almost non-existent, demonstrating that clusters in middle-aged donors grew during adulthood. Computational analysis showed that germline selection is the only plausible explanation. Testes of men aged 75-80 were heterogeneous with some like middle-aged and others like younger testes. Incorporating data on age-dependent death of spermatogonial stem cells explains the results from all age groups. Germline selection also explains MEN2B's male mutation bias and paternal age effect. Our discovery focuses attention on MEN2B as a model for understanding the genetic and biochemical basis of germline selection. Since RET function in mouse spermatogonial stem cells has been extensively studied, we are able to suggest that the MEN2B mutation provides a selective advantage by altering the PI3K/AKT and SFK signaling pathways. Mutations that are preferred in the germline but reduce the fitness of offspring increase the population's mutational load. Our approach is useful for studying other disease mutations with similar characteristics and could uncover additional germline selection pathways or identify true mutation hot spots.


Subject(s)
Germ-Line Mutation , Multiple Endocrine Neoplasia Type 2b/epidemiology , Multiple Endocrine Neoplasia Type 2b/genetics , Proto-Oncogene Proteins c-ret/genetics , Thyroid Neoplasms/epidemiology , Thyroid Neoplasms/genetics , Adult , Age Factors , Aged , Aging/genetics , Animals , Humans , Male , Mice , Middle Aged , Models, Genetic , Multiple Endocrine Neoplasia Type 2b/pathology , Proto-Oncogene Mas , Signal Transduction/genetics , Spermatogenesis/genetics , Spermatogonia/metabolism , Spermatogonia/pathology , Syndrome , Testis/metabolism , Testis/pathology , Thyroid Neoplasms/pathology , Young Adult
11.
Proc Natl Acad Sci U S A ; 105(29): 10143-8, 2008 Jul 22.
Article in English | MEDLINE | ID: mdl-18632557

ABSTRACT

Two nucleotide substitutions in the human FGFR2 gene (C755G or C758G) are responsible for virtually all sporadic cases of Apert syndrome. This condition is 100-1,000 times more common than genomic mutation frequency data predict. Here, we report on the C758G de novo Apert syndrome mutation. Using data on older donors, we show that spontaneous mutations are not uniformly distributed throughout normal testes. Instead, we find foci where C758G mutation frequencies are 3-4 orders of magnitude greater than the remaining tissue. We conclude this nucleotide site is not a mutation hot spot even after accounting for possible Luria-Delbruck "mutation jackpots." An alternative explanation for such foci involving positive selection acting on adult self-renewing Ap spermatogonia experiencing the rare mutation could not be rejected. Further, the two youngest individuals studied (19 and 23 years old) had lower mutation frequencies and smaller foci at both mutation sites compared with the older individuals. This implies that the mutation frequency of foci increases as adults age, and thus selection could explain the paternal age effect for Apert syndrome and other genetic conditions. Our results, now including the analysis of two mutations in the same set of testes, suggest that positive selection can increase the relative frequency of premeiotic germ cells carrying such mutations, although individuals who inherit them have reduced fitness. In addition, we compared the anatomical distribution of C758G mutation foci with both new and old data on the C755G mutation in the same testis and found their positions were not correlated with one another.


Subject(s)
Acrocephalosyndactylia/genetics , Germ-Line Mutation , Receptor, Fibroblast Growth Factor, Type 2/genetics , Selection, Genetic , Acrocephalosyndactylia/pathology , Adult , Age Factors , Base Sequence , DNA Mutational Analysis , DNA Primers/genetics , Humans , Male , Middle Aged , Models, Genetic , Paternal Age , Point Mutation , Spermatogonia/metabolism , Spermatogonia/pathology , Testis/metabolism , Testis/pathology
12.
J Biomater Sci Polym Ed ; 19(3): 311-24, 2008.
Article in English | MEDLINE | ID: mdl-18325233

ABSTRACT

A new series of poly(ethylene glycol)(PEG)-paclitaxel conjugates that increases water solubility of paclitaxel was synthesized. We developed well-designed self-immolating linkers between a drug and a water-soluble polymer moiety which gave an extremely rapid hydrolysis rate to convert a pro-drug into a parent drug without any reduction in drug efficacy. The self-immolating spacer groups were introduced between the solubilizing PEG and C7-OH of paclitaxel in order to control the rate of enzymatic hydrolysis. All these pro-drugs had a water-solubility of 400 mg/ml or more compared with a solubility of about 0.01 mg/ml. The rate of hydrolysis for the pro-drugs in rat plasma showed considerable variation of t((1/2)) ranging from 0.94 min to 42.7 min. To evaluate the anti-tumor efficacy of the pro-drug which had the fastest enzymatic hydrolysis rate, the growth inhibitory effect (IC(50)), the anti-tumor activity and the anti-metastatic potential of the pro-drug were examined. The pro-drug was potent to inhibit the growth of various cancer cell lines, such as human lung, ovarian, colon and melanoma cancer cells. On the development of melanoma lung colonies in C57B/6 mice following intravenous administration of metastatic murine B16/F10 melanoma cells, the pro-drug seems to be more efficacious than paclitaxel. The reduction of the number of melanoma lung colonies was 46.9% (dose: 5 mg/kg) with pure paclitaxel, and 24.5%, and 40.0% with the pro-drug in the dose of 0.71 mg paclitaxel equivalent/kg and 1.42 mg paclitaxel equivalent/kg, respectively.


Subject(s)
Antineoplastic Agents, Phytogenic/chemical synthesis , Paclitaxel/chemistry , Prodrugs/chemical synthesis , Animals , Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/pharmacology , Cell Line, Tumor , Drug Carriers , Humans , Hydrolysis , Male , Mice , Mice, Inbred C57BL , Polyethylene Glycols/chemistry , Prodrugs/chemistry , Prodrugs/pharmacology , Solubility , Water/chemistry
13.
Naunyn Schmiedebergs Arch Pharmacol ; 373(1): 30-6, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16521007

ABSTRACT

Sphingosylphosphorylcholine (SPC) is a vasoconstricting lysosphingolipid, and the RhoA/Rho-kinase pathway plays an important role in SPC-induced contraction. Since RhoA/Rho-kinase-mediated signaling is involved in the generation and/or maintenance of hypertension, we compared the effect of SPC on the contractility of endothelium-denuded small mesenteric arteries in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Fura-2 Ca2+ signals, contractile responses, and phosphorylation of 20-kDa myosin light chains (MLC20) were measured. Ten microM SPC induced a gradual and sustained vasoconstriction, which was greater in arteries of the SHR (82.5 +/- 4.3%, n=9) than in those of the WKY (26.7 +/- 4.5%, n=10). In Ca2+-free media, SPC gradually increased vascular tone in the SHR, but caused little vasoconstriction in the WKY. In the SHR and WKY, SPC evoked a greater vasoconstriction than did high K+ depolarization at a given Ca2+ ratio, and the Ca2+ ratio-tension curve induced by SPC was significantly shifted to the left compared with that induced by high K+ depolarization. However, the magnitude of shift to the left was greater in the SHR than in the WKY. The Rho-kinase inhibitor Y-27632 significantly inhibited SPC-induced contractions, but neither the protein kinase C inhibitor calphostin-C nor PD98059, which inhibits activation of some mitogen-activated protein kinases, had any effect on the SHR or the WKY. SPC significantly increased the phosphorylation of MLC20 in both the SHR and the WKY, and Y-27632 inhibited the SPC-induced increase in MLC(20) phosphorylation in the SHR. Our results suggest that SPC induces greater vascular tone in the SHR than in the WKY. Furthermore, our results indicate that activation of the Rho-kinase pathway plays an important role in the SPC-induced Ca2+ sensitization in the SHR.


Subject(s)
Calcium/metabolism , Hypertension/physiopathology , Mesenteric Arteries/drug effects , Phosphorylcholine/analogs & derivatives , Sphingosine/analogs & derivatives , Vasoconstriction/drug effects , Amides/pharmacology , Animals , Flavonoids/pharmacology , Mesenteric Arteries/physiology , Mitogen-Activated Protein Kinases/physiology , Myosin Light Chains/metabolism , Naphthalenes/pharmacology , Phosphorylation , Phosphorylcholine/pharmacology , Protein Kinase C/physiology , Pyridines/pharmacology , Rats , Rats, Inbred SHR , Rats, Inbred WKY , Sphingosine/pharmacology , rho-Associated Kinases/physiology
14.
Nature ; 424(6944): 81-4, 2003 Jul 03.
Article in English | MEDLINE | ID: mdl-12819662

ABSTRACT

The many types of insect ear share a common sensory element, the chordotonal organ, in which sound-induced antennal or tympanal vibrations are transmitted to ciliated sensory neurons and transduced to receptor potentials. However, the molecular identity of the transducing ion channels in chordotonal neurons, or in any auditory system, is still unknown. Drosophila that are mutant for NOMPC, a transient receptor potential (TRP) superfamily ion channel, lack receptor potentials and currents in tactile bristles but retain most of the antennal sound-evoked response, suggesting that a different channel is the primary transducer in chordotonal organs. Here we describe the Drosophila Nanchung (Nan) protein, an ion channel subunit similar to vanilloid-receptor-related (TRPV) channels of the TRP superfamily. Nan mediates hypo-osmotically activated calcium influx and cation currents in cultured cells. It is expressed in vivo exclusively in chordotonal neurons and is localized to their sensory cilia. Antennal sound-evoked potentials are completely absent in mutants lacking Nan, showing that it is an essential component of the chordotonal mechanotransducer.


Subject(s)
Calcium Channels/metabolism , Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Hearing/physiology , Amino Acid Sequence , Animals , CHO Cells , Calcium/metabolism , Calcium Channels/chemistry , Calcium Channels/genetics , Calcium Signaling , Cricetinae , Drosophila Proteins/chemistry , Drosophila Proteins/genetics , Drosophila melanogaster/anatomy & histology , Drosophila melanogaster/genetics , Evolution, Molecular , Gene Deletion , Gene Expression Profiling , Molecular Sequence Data , Neurons/metabolism , Osmotic Pressure , Patch-Clamp Techniques , Transient Receptor Potential Channels
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