ABSTRACT
BACKGROUND: Many factors interfering with a listener attempting to grasp speech in noisy environments. The spatial hearing by which speech and noise can be spatially separated may play a crucial role in speech recognition in the presence of competing noise. This study aimed to assess whether, and to what degree, spatial hearing benefit speech recognition in young normal-hearing participants in both quiet and noisy environments. METHODS: Twenty-eight young participants were tested by Mandarin Hearing In Noise Test (MHINT) in quiet and noisy environments. The assessment method used was characterized by modifications of speech and noise configurations, as well as by changes of speech presentation mode. The benefit of spatial hearing was measured by speech recognition threshold (SRT) variation between speech condition 1 (SC1) and speech condition 2 (SC2). RESULTS: There was no significant difference found in the SRT between SC1 and SC2 in quiet. SRT in SC1 was about 4.2 dB lower than that in SC2, both in speech-shaped and four-babble noise conditions. SRTs measured in both SC1 and SC2 were lower in the speech-shaped noise condition than in the four-babble noise condition. CONCLUSION: Spatial hearing in young normal-hearing participants contribute to speech recognition in noisy environments, but provide no benefit to speech recognition in quiet environments, which may be due to the offset of auditory extrinsic redundancy against the lack of spatial hearing.
Subject(s)
Hearing/physiology , Speech Perception/physiology , Adolescent , Adult , Auditory Threshold/physiology , Female , Humans , Male , Noise , Speech Reception Threshold Test , Young AdultABSTRACT
BACKGROUND: It has been pointed out that only low-dose arsenic trioxide (ATO) presents therapeutic benefits outweighing the toxic side effects. Low-dose ATO can effectively alleviate acute promyelocytic leukemia (APL). However, it is quite challenging in treating solid tumors. The purpose of this study was to investigate the effect of ATO at low concentrations on the metastatic potential of mouse hepatoma H(22) cells and the anti-metastatic mechanism of ATO. METHODS: The metastatic potential of H(22) cells was evaluated by adhesion, migration and invasion assays after exposure to a low dose of ATO in vitro. The mouse lung metastatic model induced by injection of H(22) cells via the tail vein was adopted for the evaluation of metastatic potential. Different proteins in the lysate of H(22) cells exposed to ATO at different concentrations were investigated by surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Finally, Western blotting analyses were made to detect the expression pattern of MMP-2 and nm23-M1 proteins. RESULTS: Significant cell death started at ATO concentrations above 2 micromol/L. The growth and adhesion potential of H(22) cells was inhibited in a time- and dose-dependent manner, and the migration and invasion potential of H(22) cells was inhibited in a dose-dependent manner while ATO concentration was below 2 micromol/L. Mice injected with ATO at a dose of 0.5 mg/kg had fewer lung metastases. However, mice injected with ATO at a dose of 2 mg/kg or 4 mg/kg had a high mortality rate and more liver injuries. A total of 15 different protein peaks were identified between the lysate of H(22) cells treated with ATO and controls. Two proteins that peaked at m/z 5302 and 17207 coincided with MMP-2 (fragment) and nm23-M1, respectively. Western blotting analyses demonstrated that MMP-2 and MMP-2 fragments were down-regulated and nm23-M1 was up-regulated in H(22) cells treated with 2 micromol/L ATO for 48 hours. CONCLUSIONS: ATO at a low dose inhibits the metastatic potential of mouse hepatoma H(22) cells in vitro and in vivo, and involves down-regulation of MMP-2 and up-regulation of nm23-M1.
Subject(s)
Antineoplastic Agents/pharmacology , Arsenicals/pharmacology , Carcinoma, Hepatocellular/pathology , Cell Movement/drug effects , Cell Proliferation/drug effects , Liver Neoplasms/pathology , Oxides/pharmacology , Animals , Antineoplastic Agents/adverse effects , Arsenic Trioxide , Arsenicals/adverse effects , Carcinoma, Hepatocellular/metabolism , Cell Adhesion/drug effects , Cell Line, Tumor , Cell Survival/drug effects , Disease Models, Animal , Dose-Response Relationship, Drug , Liver Neoplasms/metabolism , Lung Neoplasms/prevention & control , Lung Neoplasms/secondary , Male , Matrix Metalloproteinase 2/metabolism , Mice , NM23 Nucleoside Diphosphate Kinases/metabolism , Oxides/adverse effects , Spectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationABSTRACT
OBJECTIVE: To investigate the effective way to test 4-year-old children's ability of sound localization in the horizontal plane. METHODS: Using minimum audible angle (MAA) measure procedure on the basis of conditioned play audiometry, sound localization test was conducted for 4-year-old children at 0 degrees , +/- 45 degrees , +/- 90 degrees , +/- 135 degrees and 180 degrees standard positions in the horizontal plane. RESULTS: The outcome of sound localization test for 4-year-old children separately were: MAA (0 degrees ) = (3.80 +/- 0.71) degrees , MAA (-45 degrees ) = (7.70 +/- 1.27) degrees , MAA (45 degrees ) = (7.10 +/- 1.39) degrees , MAA (-90 degrees ) = (8.15 +/- 2.38) degrees , MAA (90 degrees ) = (7.61 +/- 2.47) degrees , MAA (-135 degrees ) = (8.85 +/- 2.70) degrees , MAA (135 degrees ) = (8.30 +/- 1.42) degrees , MAA (180 degrees ) = (5.20 +/- 1.27) degrees . The MAA of eight standard positions were less than 10 degrees , and the MAA (0 degrees ) was the smallest one. CONCLUSIONS: Our findings suggest that MAA test procedure on the basis of conditioned play audiometry could be used to evaluate the ability of sound localization in 4-year-old children.
