In vivo Tracking of Mesenchymal Stem Cells Labeled with a Novel Chitosan-coated Superparamagnetic Iron Oxide Nanoparticles using 3.0T MRI

This study aimed to characterize and MRI track the mesenchymal stem cells labeled with chitosan-coated superparamagnetic iron oxide (Chitosan-SPIO). Chitosan-SPIO was synthesized from a mixture of FeCl2 and FeCl3. The human bone marrow derived mesenchymal stem cells (hBM-MSC) were labeled with 50 microg Fe/mL chitosan-SPIO and Resovist. The labeling efficiency was assessed by iron content, Prussian blue staining, electron microscopy and in vitro MR imaging. The labeled cells were also analyzed for cytotoxicity, phenotype and differentiation potential. Electron microscopic observations and Prussian blue staining revealed 100% of cells were labeled with iron particles. MR imaging was able to detect the labeled MSC successfully. Chitosan-SPIO did not show any cytotoxicity up to 200 microgram Fe/mL concentration. The labeled stem cells did not exhibit any significant alterations in the surface markers expression or adipo/osteo/chondrogenic differentiation potential when compared to unlabeled control cells. After contralateral injection into rabbit ischemic brain, the iron labeled stem cells were tracked by periodical in vivo MR images. The migration of cells was also confirmed by histological studies. The novel chitosan-SPIO enables to label and track MSC for in vivo MRI without cellular alteration.

Clinical Comparison of the Auditory Steady-State Response with the Click Auditory Brainstem Response in Infants

OBJECTIVES: Our goal was to determine the effectiveness of using the auditory steady state response (ASSR) as a measure of hearing thresholds in infants who are suspected of having significant hearing loss, as compared with using the click-auditory brainstem response (C-ABR). METHODS: We retrospectively analyzed the audiologic profiles of 76 infants (46 boys and 30 girls, a total of 151 ears) who ranged in age from 1 to 12 months (average age: 5.7 months). The auditory evaluations in 76 infants who were suspected of having hearing loss were done via the C-ABR and ASSR. In addition, for reference, the mean ASSR thresholds were compared to those of 39 ears of infants and 39 ears of adults with normal hearing at 0.5, 1, 2, and 4 kHz. RESULTS: The highest correlation between the C-ABR and ASSR thresholds was observed at an average of 2-4 kHz (r=0.94). On comparison between the hearing of infants and adults at 0.5, 1, 2, and 4 kHz, the mean ASSR threshold in infants was 12, 7, 8, and 7 dB higher, respectively, than that in adults. CONCLUSION: ASSR testing may provide additional audiometric information for accurately predicting the hearing sensitivity, and this is essential for the management of infants with severe to profound hearing loss.

The Validity Using Two-stage Automated Auditory Brainstem Response as a Universal Newborn Hearing Screening Protocol : Experiences in Asan Medical Center / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Universal newborn hearing screening is widely accepted due to socioeconomic harm of congenital hearing loss. The aim of this study was to assess whether two-stage automated auditory brainstem response (AABR) is acceptable method for newborn hearing screening and to check the presence of potential false negative cases by using another criterion considering sweep number. SUBJECTS AND METHOD: Among 3761 neonates who were born from March 2004 to December 2005, 3053 healthy neonates (81.18%) whose parents agreed to hearing screening protocol were screened with AABR. Failed neonates ('refer') at first stage test and neonates showing high sweep number (>4000) on repeated test were received second stage retest within 24 hours from the first test. Neonates whose retest AABR results were failed or high sweep number continuously were tested with conventional ABR as a confirmative study within 3 months. RESULTS: 94 neonates (3.08%) were failed and 180 neonates (5.89%) showed high sweep number on first stage AABR test. On second stage AABR test, neonates with 'final refer' result were 46 (1.51%) and neonates with 'final high sweep number' result were 44 (1.44%). Neonates with threshold of over 30 dB at ABR were 14 among final refer group and 5 among final high sweep number group. Three bilateral profound hearing loss cases were detected and proper management was done. Nine false negative cases were detected and of these, 3 neonates showed moderate hearing loss. There is no clear relationship between predicting false negative case and sweep number. CONCLUSION: Our current two stage AABR test is useful tool for newborn hearing screening with acceptable referral rate and positive predictive value. False negative cases detected through our protocol have no clear relationship with high sweep number.

The Correlation between Pure Tone Audiometry and Auditory Steady State Response according to the Hearing Level and Frequency / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The aim of this study is to assess the correlation between hearing thresholds in pure tone audiometry (PTA) and auditory steady state response (ASSR) according to the hearing level and frequency. SUBJECTS AND METHOD: A total of 105 subjects (178 ears, 64 male and 41 female) were enrolled in this study. None of the subjects had middle ear diseases and PTA and ASSR were performed on the same day for each subject. Ninety-eight subjects (168 ears) were finally enrolled in the analysis of this study. RESULTS: The correlation coefficient (r) of mean hearing threshold between PTA and ASSR was 0.96 and the mean hearing threshold of PTA can be calculated from the mean hearing threshold of ASSR (PTA=1.05 x ASSR-7.6). When analyzed according to frequency, the correlation coefficients were 0.94, 0.95, 0.94, and 0.92 for 500, 1,000, 2,000, and 4,000 Hz panels, respectively. CONCLUSION: This study showed that ASSR and PTA had very close correlation and ASSR could be used to estimate hearing thresholds with reliable accuracy in various cases where subjective hearing measurement including PTA could not be performed.