COX-2 mediates angiotensin II-induced (pro)renin receptor expression in the rat renal medulla.

(Pro)renin receptor (PRR) is predominantly expressed in the distal nephron where it is activated by angiotensin II (ANG II), resulting in increased renin activity in the renal medulla thereby amplifying the de novo generation and action of local ANG II. The goal of the present study was to test the role of cycloxygenase-2 (COX-2) in meditating ANG II-induced PRR expression in the renal medulla in vitro and in vivo. Exposure of primary rat inner medullary collecting duct cells to ANG II induced sequential increases in COX-2 and PRR protein expression. When the cells were pretreated with a COX-2 inhibitor NS-398, ANG II-induced upregulation of PRR protein expression was almost completely abolished, in parallel with the changes in medium active renin content. The inhibitory effect of NS-398 on the PRR expression was reversed by adding exogenous PGE2. A 14-day ANG II infusion elevated renal medullary PRR expression and active and total renin content in parallel with increased urinary renin, all of which were remarkably suppressed by the COX-2 inhibitor celecoxib. In contrast, plasma and renal cortical active and total renin content were suppressed by ANG II treatment, an effect that was unaffected by COX-2 inhibition. Systolic blood pressure was elevated with ANG II infusion, which was attenuated by the COX-2 inhibition. Overall, the results obtained from in vitro and in vivo studies established a crucial role of COX-2 in mediating upregulation of renal medullary PRR expression and renin content during ANG II hypertension.

Discrimination of consonants in quiet and in noise in Mandarin-speaking children with normal hearing.

OBJECTIVE: Given the critical role of consonants in speech perception and the lack of knowledge on consonant perception in noise in Mandarin-speaking children, the current study aimed to investigate Mandarin consonant discrimination in normal-hearing children, in relation to the effects of age and signal-to-noise ratios (S/N). DESIGN: A discrimination task consisting of 33 minimal pairs in monosyllabic words was designed to explore the development of consonant discrimination in five test conditions: 0, -5, -10, -15 dB S/Ns, and quiet. STUDY SAMPLE: Forty Mandarin-speaking, normal-hearing children aged from 4;0 to 8;9 in one-year-age increment were recruited and their performance was compared to 10 adult listeners. RESULTS: A significant main effect of age, test conditions, and an interaction effect between these variables was noted. Consonant discrimination in quiet and in noise improved as children became older. Consonants that were difficult to discriminate in quiet and in noise were mainly velar contrasts. Noise seemed to have less effect on the discrimination of affricates and fricatives, and plosives appeared to be to be more difficult to discriminate in noise than in quiet. Place contrasts between alveolar and palato-alveolar consonants were difficult in quiet. CONCLUSIONS: The findings were the first to reveal typical perceptual development of Mandarin consonant discrimination in children and can serve as a reference for comparison with children with disordered perceptual development, such as those with hearing loss.

An ERP Study on the Auditory Stream Segregation in Cochlear Implant Simulations: Effects of Frequency Separation and Time Interval.

Auditory stream segregation is an important function of the auditory system, and the extent to which this function works has a major impact on listener's ability to recognize auditory objects in complex listening environments. However, cochlear implant (CI) listeners are poorly equipped for this challenge, mainly owing to the impoverished sensory information available via their implants. The purpose of this study was to examine two factors, i.e., frequency separation and time interval, affecting the auditory stream segregation in vocoder simulations simulating CI speech processing based on an event-related potential (ERP) experiment. The pure-tone stimuli were processed by a vocoding process, and presented to normal-hearing listeners in an ERP experiment. Experimental results showed that a large frequency separation or a short time interval led to a larger mismatch negativity (MMN) response. The MMN results in this work suggested that the degree of auditory stream segregation was affected by frequency separation and time interval, and MMN could serve as a potential index for future ERP studies on auditory stream segregation in CI users.

Assessing the Importance of Lexical Tone Contour to Sentence Perception in Mandarin-Speaking Children With Normal Hearing.

Purpose: The aim of the present study was to evaluate the influence of lexical tone contour and age on sentence perception in quiet and in noise conditions in Mandarin-speaking children ages 7 to 11 years with normal hearing. Method: Test materials were synthesized Mandarin sentences, each word with a manipulated lexical contour, that is, normal contour, flat contour, or a tone contour randomly selected from the four Mandarin lexical tone contours. A convenience sample of 75 Mandarin-speaking participants with normal hearing, ages 7, 9, and 11 years (25 participants in each age group), was selected. Participants were asked to repeat the synthesized speech in quiet and in speech spectrum-shaped noise at 0 dB signal-to-noise ratio. Results: In quiet, sentence recognition by the 11-year-old children was similar to that of adults, and misrepresented lexical tone contours did not have a detrimental effect. However, the performance of children ages 9 and 7 years was significantly poorer. The performance of all three age groups, especially the younger children, declined significantly in noise. Conclusions: The present research suggests that lexical tone contour plays an important role in Mandarin sentence recognition, and misrepresented tone contours result in greater difficulty in sentence recognition in younger children. These results imply that maturation and/or language use experience play a role in the processing of tone contours for Mandarin speech understanding, particularly in noise.

Vocabulary development in Mandarin-speaking children with cochlear implants and its relationship with speech perception abilities.

BACKGROUND: China has the largest population of children with hearing impairments and cochlear implantation is gaining popularity there. However, the vocabulary development in this population is largely unexplored. AIMS: This study examined early vocabulary outcomes, factors influencing early vocabulary development and the relationship between speech perception and vocabulary development in Mandarin-speaking children during the first year of cochlear implant use. METHODS AND PROCEDURES: A battery of vocabulary tests was administered to 80 children before implantation and 3, 6, and 12 months after implantation. Demographic information was obtained to evaluate their relationships with vocabulary outcomes. OUTCOMES AND RESULTS: The Mandarin-speaking children, who received their cochlear implants before 3 years of age, developed vocabulary at a rate faster than that of their same-aged peers with normal hearing. Better pre-implant hearing levels, younger age at implantation, and higher maternal education level contributed to the early vocabulary development. The trajectories of speech perception development highly correlated with those of vocabulary development during 3 to 12 months of CI use. CONCLUSIONS: and Implications: These findings imply that the vocabulary development of children implanted before 3 years of age may catch up with that of their hearing peers.

Known-Groups and Concurrent Validity of the Mandarin Tone Identification Test (MTIT).

OBJECTIVE: The Mandarin Tone Identification Test (MTIT) is a new test designed to assess the tone identification abilities of children with hearing impairment (HI). Evidence for reliability and sensitivity has been reported. The present study aimed to evaluate the known-groups and concurrent validity of the MTIT. DESIGN: The MTIT and Mandarin Pediatric Speech Intelligibility test (MPSI) were administered in quiet and in noise conditions. The known-groups validity was evaluated by comparing the performance of the MTIT on children with two different levels of HI. The MPSI was included to evaluate the concurrent validity of the MTIT. STUDY SAMPLE: 81 children with HI were recruited in the present study. They were Mandarin-speaking children with profound HI (mean age = 9; 0, n = 41) and with moderate to severe HI (mean age = 8; 9, n = 40). RESULTS: Scores on the MTIT differed between the two groups with different hearing levels suggesting good known-groups validity. A strong relationship between tone and sentence perception both in quiet and in noise provided preliminary evidence for concurrent validity. CONCLUSIONS: The present study confirmed that the MTIT has good known-groups validity and provided preliminary evidence for concurrent validity. The MTIT could be used to evaluate tone identification ability in children with HI with confidence.

Early speech perception in Mandarin-speaking children at one-year post cochlear implantation.

PURPOSE: The aim in this study was to examine early speech perception outcomes in Mandarin-speaking children during the first year of cochlear implant (CI) use. METHOD: A hierarchical early speech perception battery was administered to 80 children before and 3, 6, and 12 months after implantation. Demographic information was obtained to evaluate its relationship with these outcomes. RESULTS: Regardless of dialect exposure and whether a hearing aid was trialed before implantation, implant recipients were able to attain similar pre-lingual auditory skills after 12 months of CI use. Children speaking Mandarin developed early Mandarin speech perception faster than those with greater exposure to other Chinese dialects. In addition, children with better pre-implant hearing levels and younger age at implantation attained significantly better speech perception scores after 12 months of CI use. Better pre-implant hearing levels and higher maternal education level were also associated with a significantly steeper growth in early speech perception ability. CONCLUSIONS: Mandarin-speaking children with CIs are able to attain early speech perception results comparable to those of their English-speaking counterparts. In addition, consistent single language input via CI probably enhances early speech perception development at least during the first-year of CI use.

[Application of the Mandarin Tone Identification Test (MTIT) in children with hearing impairment].

OBJECTIVE: The present study aimed to evaluate the Mandarin tone identification ability in children with hearing impairment (HI) in quiet and in noise using the new developed Mandarin Tone Identification Test (MTIT), and to evaluate the practical application of MTIT. METHOD: Subjects were Mandarin-speaking children with moderate, severe and profound HI and aged from 5 to 12 years (n = 81, Male = 37, Female = 44). The MTIT was administered in five test conditions: in quiet and in -10, -5, 0 and +5 dB signal-to-noise ratios (S/N). RESULTS: The degree of HI significantly influenced the tone identification ability. The tone identification performance of children with moderate to severe HI was significantly better than that of children with profound HI. However, when compared with children with normal hearing, the performance of children with moderate to severe HI was not satisfactory. Among the six tone contrasts, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts were the most difficult tone contrasts for children with profound HI and the Tone 2/Tone 3 contrast was the most difficult for children with moderate to severe HI in quiet. CONCLUSIONS: MTIT could be used to examine tone perception ability of children with hearing aids. In quiet, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts are difficult to identify, while six tone contrasts are all difficult to identify for children with HI in noise. In future, the MTIT can also be used to evaluate the tone identification ability on children cochlear implants.

A Structural Equation Modeling Approach to Examining Factors Influencing Outcomes with Cochlear Implant in Mandarin-Speaking Children.

OBJECTIVE: To examine the direct and indirect effects of demographical factors on speech perception and vocabulary outcomes of Mandarin-speaking children with cochlear implants (CIs). METHODS: 115 participants implanted before the age of 5 and who had used CI before 1 to 3 years were evaluated using a battery of speech perception and vocabulary tests. Structural equation modeling was used to test the hypotheses proposed. RESULTS: Early implantation significantly contributed to speech perception outcomes while having undergone a hearing aid trial (HAT) before implantation, maternal educational level (MEL), and having undergone universal newborn hearing screening (UNHS) before implantation had indirect effects on speech perception outcomes via their effects on age at implantation. In addition, both age at implantation and MEL had direct and indirect effects on vocabulary skills, while UNHS and HAT had indirect effects on vocabulary outcomes via their effects on age at implantation. CONCLUSION: A number of factors had indirect and direct effects on speech perception and vocabulary outcomes in Mandarin-speaking children with CIs and these factors were not necessarily identical to those reported among their English-speaking counterparts.

Consonant discrimination by Mandarin-speaking children with prelingual hearing impairment.

OBJECTIVES: Little is known about the consonant discrimination ability of Mandarin-speaking children with prelingual hearing impairment (HI) and fitted with hearing aids (HAs). The present study aimed to evaluate Mandarin consonant discrimination ability in children with HI, and explore the effects of unaided and aided hearing threshold, the age of first HA fitting and the duration of HA use on consonant discrimination ability. METHODS: Subjects were Mandarin-speaking children aged 5;4-12;6 years with profound HI (n=41), children aged 6;1-12;4 years with severe HI (n=26), and children aged 5;0-11;9 years with moderate HI (n=9). The Mandarin Consonant Discrimination Test was administered in six test conditions: -10, -5, 0, 5 and 10dB signal to noise ratios (S/Ns) and quiet. HAs were in the usual user's settings, adjusted to match the manufacturer prescribed settings and individual preferences, and the volume was set to comfortable listening level. RESULTS: The results revealed that /p(h)/-/t(h)/, /ts/-/tʂ/ and /ʐ/-/l/ were the most difficult and /p/-/p(h)/, /t/-/t(h)/, /tɕ/-/tɕ(h)/ and /k/-/k(h)/ were the easiest consonant minimal pairs to discriminate in quiet both for children with profound HI and those with moderate to severe HI. In noise, no significant difference in performance was found among all consonant minimal pairs. A backward elimination stepwise multiple linear regressions revealed that unaided hearing level accounted for 25.4% of the variance in consonant discrimination performance in noise at 10dB S/N and 30.4% in quiet. However, aided hearing threshold, the age of first HA fitting and the duration of HA use did not significantly predict consonant discrimination ability both in quiet and in noise. CONCLUSIONS: Consonant discrimination performance of children with profound HI was poorer than those with moderate to severe HI. The ability to discriminate consonant pairs seems to depend on age of acquisition of the consonants. Although the age of first HA fitting and the duration of HA use were not correlated with consonant discrimination outcomes, this finding does not preclude the importance of early HA fitting.

The bioavailability of the soluble algal products of different microalgal strains and its influence on microalgal growth in unsterilized domestic secondary effluent.

Soluble algal products (SAPs) accumulated in microalgal culture could be used as carbon source by bacteria, and thus induce serious bacteria contamination. In this study, three freshwater microalgal strains, Scenedesmus sp. LX1 (S. LX1), Chlorella ellipsoidea YJ1 (C. YJ1) and Haematococcus pluvialis (H. pluvialis), were used to investigate the bioavailability of SAPs and its influence on microalgal growth in unsterilized domestic secondary effluent. S. LX1 and H. pluvialis could grow well whether secondary effluent was sterilized or not, while C. YJ1 showed poor growth without sterilization. The assimilable organic carbon (AOC) concentration and AOC content in the SAPs of C. YJ1 was as high as 180µg-CL(-1) and 3.2%, respectively, which induced more serious bacteria contamination and thus inhibited the growth of C. YJ1. Based on the results, in microalgal strain selection for massive cultivation, AOC assays of SAPs could be applied to examine microalgal susceptibility to bacteria contamination.

Tone identification in Mandarin-speaking children with profound hearing impairment.

OBJECTIVES: Little is known about the tone identification ability of Mandarin-speaking children with profound hearing impairment (HI) and fitted with hearing aids (HAs). The present study aimed to evaluate the Mandarin tone identification ability in children with profound HI and fitted with HAs, and explore the effects of hearing thresholds, the age of first HA fitting and the duration of HA use on Mandarin tone identification ability. METHODS: Subjects were Mandarin-speaking children aged 5;4-12;6 years with profound HI (n=41). The Mandarin Tone Identification Test was administered in five test conditions: in -10, -5, 0 and 5dB signal-to-noise ratios (S/Ns) and quiet. Hearing aids were in the usual user's settings, optimized for the best speech reception, and the volume was set to comfortable listening level. RESULTS: Two-way repeated measures ANOVA showed significant effects of test conditions and tone contrasts in Mandarin tone identification. Post-hoc pairwise comparisons showed significant difference in performance among the five test conditions. Results also indicated that, among the six tone contrasts, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts were the most difficult tone contrasts in quiet. No significant difference in performance was found among the six tone contrasts in noise. Pearson product-moment correlation showed that the age of first HA fitting, the duration of HA use, aided and unaided average thresholds as well as the aided hearing thresholds in the low frequency region were not significantly correlated with tone identification ability in the five test conditions. CONCLUSIONS: Consistent with previous findings, the Tone 1/Tone 2 and Tone 2/Tone 3 contrasts were the most difficult to identify in quiet; but the presence of noise resulted in these tone contrasts being equally difficult. Findings also suggest that the tone identification ability of children with profound HI needs to be improved. Although the age of first HA fitting and the duration of HA use were not significantly correlated with tone identification performance in children with profound HI, this finding does not preclude the importance of early HA fitting.

Development and validation of a new Mandarin tone identification test.

OBJECTIVES: The objectives of this study were to develop a new Mandarin tone identification test (MTIT) to assess the Mandarin tone identification ability of children with hearing impairment (HI) and at age around 7 years; and to evaluate the reliability and sensitivity of the MTIT. METHODS: The word materials to be used in the MTIT were developed in Phase I. Monosyllables were chosen to represent the daily repertoire of young children and to avoid the influence of co-articulation and intonation. Each test stimulus set contained four words, with one target, one containing contrastive tone, and two unrelated distracters. All words were depicted using simple pictures, and the test targets in quiet or in noise were presented using recorded stimuli on a custom software. Phase II evaluated the reliability and sensitivity of the MTIT. Participants were 50 normal-hearing native-Mandarin speakers around 7 years of age. RESULTS: In Phase I, the MTIT was developed as described above. The final test consists of 51 words that are within the vocabulary repertoire of children aged 7 years. In Phase II, with the Mandarin tone identification scores collected from 50 children, the repeated measure ANOVA showed a significant main effect of S/N on MTIT performance (p<0.001). Pairwise comparisons revealed a significant difference in performance across the five S/N conditions (p<0.01) when S/N varied from -30 to -10dB. Cronbach's alpha at -15dB S/N was 0.66, suggesting satisfactory internal consistency reliability. A paired-samples t-test showed that there was no significant difference between the test-retest scores across the five S/N conditions (p>0.05). CONCLUSIONS: Compared with the available Mandarin tone identification tools, MTIT systematically evaluated the tone identification performance in noisy environment for normal hearing children at age around 7 years. Results also showed satisfactory internal consistency reliability, good test-retest reliability and good sensitivity. In the near future, MTIT could be used to evaluate tone perception ability of children with hearing impairment and help to design hearing rehabilitation strategies for this population at the age critical for their language learning.

Isolation and heterotrophic cultivation of mixotrophic microalgae strains for domestic wastewater treatment and lipid production under dark condition.

Cultivating microalgae heterotrophically could overcome the light dependency, and thus increase the yield of microalgal lipid per unit area. In this study, three newly isolated strains of microalgae (Scenedesmus sp. ZTY2, Scenedesmus sp. ZTY3 and Chlorella sp. ZTY4) from a domestic wastewater treatment plant were heterotrophically cultivated in domestic wastewater with no illumination. During the cultivation, the algal densities of Scenedesmus species and Chlorella species were increased by 203.0% and 60.5% comparing with the initial densities, respectively. After 11-day cultivation, the lipid contents of Scenedesmus sp. ZTY2, Scenedesmus sp. ZTY3 and Chlorella sp. ZTY4 reached 69.1%, 55.3% and 79.2%, respectively. The DOC removal efficiencies of these three strains were 63.4%, 52.9% and 64.4%, and the biomass yield were 1.65, 1.98 and 2.31mg biomass/mg DOC, respectively. This is the first report about the heterotrophic cultivation of microalgae strains for domestic wastewater treatment and lipid production under dark condition.