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Biomedical subjects

Fei Zhao

Publications and source records attributed to Fei Zhao.

29 records · Page 2Linked to original sources
PubMed2005

[The cloning of human Smac gene and its pro-apoptotic effect on Burkitt's lymphoma cells].

OBJECTIVE: Second mitochondria-derived activator of caspase (Smac) is a recently identified, novel pro-apoptotic molecule, which is released from mitochondria into the cytosol during apoptosis. Smac promotes activation of caspases by neutralizing members of the inhibitor of apoptosis proteins (IAPs) family, such as X-linked inhibitor of apoptosis protein (XIAP). The objective of the study was to examine the pro-apoptotic effect of human Smac gene on Burkitt's lymphoma Raji cells. METHODS: The full length cDNA of human Smac gene was amplified by reverse transcription-PCR from total RNA of HEK-293 cells. The PCR product was ligated with linearized vector pGEM-T-easy supplied in the TA cloning kit and sequenced. The correct cDNA of full length Smac was subcloned into eukaryocytic expression vector pcDNA3.1/myc-his and transfected into human Burkitt's lymphoma cell line Raji by lipofectamine-mediated transfection. The expression of full length Smac was determined by Western blot. Morphological observation was done with the laser scanning confocal microscope by double staining the Raji cells with Hoechest 33,258 and propidium iodide. Flow cytometry was used to evaluate apoptosis. Relative caspase-3 activity was determined by colorimetric assay. RESULTS: Recombinant eukaryocytic expression vector pcDNA3.1/Smac, which contained full length Smac, was successfully constructed. After pcDNA 3.1/Smac was transfected into human Burkitt's lymphoma Raji cell line for 24 hours, Raji cells showed apparent apoptosis with a percentage of (43.7 +/- 2.5)%, which was higher than that of non-transfected group and free vector-transfected group (P < 0.05). Compared with non-transfected group (0.136 +/- 0.036) and free vector-transfected group (0.138 +/- 0.026), the relative caspase-3 activity of Raji cells transfected by pcDNA3.1/Smac (0.936 +/- 0.041) was significantly enhanced (P < 0.05). CONCLUSION: Transfection and expression of human Smac gene could significantly induce apoptosis of human Burkitt's lymphoma Raji cells. The mechanism is associated with the increase of caspase-3 activity.

Apoptosis↗
PubMed2005

[Suppressive effects of par-4 antisense oligodeoxynucleotide on up-regulation of intracellular calcium concentration in PC12 cell induced by glutamate and its anti-apoptosis effects].

OBJECTIVE: To investigate the uppressive effects of par-4 antisense oligodeoxynucleotide on the up-regulation of intracellular calcium concentration in PC12 cell induced by glutamate and its anti-apoptosis effects. METHODS: Cationic lipid-mediated par-4 antisense oligodeoxynucleotide (par-4-AS-ODN) was transfected into PC12 cells and followed by glutamate for treatment. Mismatch oligodeoxy-nucleotide (MS-ODN) was used as the control. Morphological assessment and evaluation of the anti-apoptosis effects of par-4-AS-ODN on PC12 cells were performed by laser scanning confocal microscopy by double staining of the cells with Hoechest 33258/propidium iodide (Hoe/PI) and flow cytometry respectively. The mRNA and protein levels of calpain 10 and par-4 were measured by RT-PCR and Western blot. Intracellular calcium concentration was determined by using laser scanning confocal microscope with Fura-2/AM as the fluorescent dye. RESULTS: Par-4-AS-ODN repress the increase of par-4 protein in PC12 cell (52.3 +/- 5.0 vs 90.0 +/- 3.2, < 0.01). Par-4-AS-ODN significantly inhibited the apoptosis of PC12 cells induced by glutamate (53% vs 31%, < 0.01). Par-4-AS-ODN significantly suppress the up-regulation of intracellular calcium concentration in PC12 cells induced by glutamate (Rate of fluorescent density: 167.9 +/- 32.4 vs 228.8 +/- 36.8, < 0.01). Par-4-AS-ODN inhibited the increase of calpain 10 mRNA in PC12 cells induced by glutamate (46.3 +/- 3.7 vs 34.8 +/- 2.1, < 0.01). CONCLUSIONS: par-4-AS-ODN enables to inhibit apoptosis of PC12 cells induced by glutamate. The mechanism of the inhibition may be closely related to suppression of the up-regulation of intracellular calcium concentration and calpain transcription expression.

Animals↗
PubMed2003

Ear-canal acoustic admittance and reflectance effects in human neonates. I. Predictions of otoacoustic emission and auditory brainstem responses.

This report describes the extent to which ear-canal acoustic admittance and energy reflectance (YR) in human neonates (1) predict otoacoustic emission (OAE) levels and auditory brainstem response (ABR) latencies, and (2) classify OAE and ABR responses as present or absent. Analyses are reported on a subset of ears in which hearing screening measurements were obtained previously [Norton et al., Ear. Hear. 21, 348-356 (2000a)]. Tests on 1405 ears included YR, distortion-product OAEs, transient-evoked OAEs, and ABR. Principal components analysis reduced the 33 YR variables to 5-7 factors. OAE levels decreased and ABR latencies increased with increasing high-frequency energy reflectance. Up to 28% of the variance in OAE levels and 12% of the variance in ABR wave-V latencies were explained by these factors. Thus, the YR response indirectly encodes information on inter-ear variations in forward and reverse middle-ear transmission. The YR factors classify OAEs with an area under the relative operating characteristic (ROC) curve as high as 0.79, suggesting that middle-ear dysfunction is partly responsible for the inability to record OAEs in some ears. The YR factors classified ABR responses less well, with ROC areas of 0.64 for predicting wave-V latency and 0.56 for predicting Fsp.

Brain Stem↗
PubMed2003

Ear-canal acoustic admittance and reflectance measurements in human neonates. II. Predictions of middle-ear in dysfunction and sensorineural hearing loss.

This report describes relationships between middle-ear measurements of acoustic admittance and energy reflectance (YR) and measurements of hearing status using visual reinforcement audiometry in a neonatal hearing-screening population. Analyses were performed on 2638 ears in which combined measurements were obtained [Norton et al., Ear Hear. 21, 348-356 (2000)]. The measurements included distortion-product otoacoustic emissions (DPOAE), transient evoked otoacoustic emissions (TEOAE), and auditory brainstem responses (ABR). Models to predict hearing status using DPOAEs, TEOAEs, or ABRs were each improved by the addition of the YR factors as interactions, in which factors were calculated using factor loadings from Keefe et al. [J. Acoust. Soc. Am. 113, 389-406 (2003)]. This result suggests that information on middle-ear status improves the ability to predict hearing status. The YR factors were used to construct a middle-ear dysfunction test on 1027 normal-hearing ears in which DPOAE and TEOAE responses were either both present or both absent, the latter condition being viewed as indicative of middle-ear dysfunction. The middle-ear dysfunction test classified these ears with a nonparametric area (A) under the relative operating characteristic curve of A = 0.86, and classified normal-hearing ears that failed two-stage hearing-screening tests with areas A = 0.84 for DPOAE/ABR, and A = 0.81 for TEOAE/ABR tests. The middle-ear dysfunction test adequately generalized to a new sample population (A = 0.82).

Diagnosis, Differential↗
PubMed2003

Transient evoked otoacoustic emissions in patients with middle ear disorders.

The aim of this study is to investigate the middle ear dynamic characteristics and their influence on TEOAEs in patients with middle ear disorders. The middle ear dynamic characteristics and TEOAE findings were investigated in 89 patients with middle ear disorders using the sweep frequency impedance (SFI) meter and the ILO88 system, respectively. These patients were divided into six subcategories: tympanic membrane aberrations, otitis media with effusion, chronic otitis media, tympanic membrane perforation, otosclerosis, and ossicular chain dislocation. Details of the TEOAE frequency characteristics were compared with the individual's middle ear dynamic characteristics. TEOAE status as a function of hearing threshold and middle ear dynamic characteristics was also examined. The results showed that the middle ear dynamic characteristics in patients with middle ear disorders correlated with the TEOAE frequency characteristics and amplitudes. The hearing level and middle ear mobility were the controlling factors affecting TEOAE status. Using both non-linear and linear stimulus modes, larger TEOAE responses were obtained when the hearing level was better than 20 dB HL, and there was moderately good middle ear mobility. Moreover, TEOAEs were absent using the non-linear mode when the hearing level was worse than 30 dB HL, whereas with the linear mode. TEOAEs were recordable even with hearing losses of up to 40 dB HL in patients with middle ear disorders. A higher incidence of recordable TEOAEs was found in the subgroups with tympanic membrane abnormalities and secretory otitis media when compared with the other subgroups. No TEOAEs were recordable in patients with chronic otitis media.

Acoustic Impedance Tests↗
PubMed2003

[Apoptosis of keloid-derived fibroblasts induced by Fas gene transfection].

OBJECTIVE: To observe the effect of Fas gene transfection on the apoptosis of keloid-derived fibroblasts. METHODS: The full-length cDNA of Fas was inserted into the multicloning site of the expression vector pcDNA-3.1 by molecular cloning technique, and the recombinant plasmid was transfected into the keloid-derived fibroblasts via lipofectin. Fas monoclonal antibody (mAb) was used to induce the apoptosis of the cells, which was evaluated with HE staining, DNA agarose gel electrophoresis and flow cytometry. RESULTS: The expression plasmid pcDNA-3.1-Fas was constructed successfully. Fas mAb induced apoptosis of these fibroblasts transfected with Fas gene, with the typical features of fibroblast apoptosis observed in the treated cells (e.g. typical apoptotic cell nuclei, DNA ladder and high apoptosis rate as determined by flow cytometer), but not in the control cells. CONCLUSION: Blockage of upstream apoptosis pathway in keloid-derived fibroblasts is due to nonfunction of Fas protein, and mutation of Fas gene may be the pathogenesis of keloids.

Apoptosis↗
PubMed2002

Absence of hearing impairment in adult onset facioscapulohumeral muscular dystrophy.

Hearing impairment has long been associated with the rarer forms of severe childhood and infantile facioscapulohumeral muscular dystrophy. Recent studies have suggested a high prevalence in classic, adult or adolescent, onset cases as well. We undertook detailed pure tone audiometric examination of 21 adult onset facioscapulohumeral muscular dystrophy cases. Patient results were compared with normative data obtained from the (United Kingdom) National Study of Hearing (The prevalence and distribution of hearing impairment and reported hearing disability in the MRC Institute of Hearing Research's National Study of Hearing, Whurr, 1995). There was no significant difference in the prevalence of hearing impairment in facioscapulohumeral muscular dystrophy patients at any single or averaged frequency tested. In this group of patients, pure tone audiometric thresholds were consistently better in the facioscapulohumeral muscular dystrophy patients, although these reached statistical significance only at 4 and 6 kHz. Age of onset, disease duration, clinical severity, degree of facial weakness and double-digest fragment size made no significant difference to mean hearing thresholds. We conclude that hearing impairment is not more common in adult onset facioscapulohumeral muscular dystrophy, and according to this data, may even, be less prevalent than in the normal population.

Adolescent↗
PubMed2002

Middle ear dynamic characteristics in patients with otosclerosis.

OBJECTIVE: To investigate the middle ear dynamic characteristics in patients with otosclerosis using the sweep frequency impedance meter (SFI test) and conventional tympanometry, and also to evaluate the diagnostic efficiency of the SFI test for otosclerosis. DESIGN: The study was designed to collect a total of 25 (36 ears) consecutive patients with otosclerosis. All subjects followed a clinical protocol, which consisted of a hearing problem questionnaire, otoscopic examination, and audiometric measurements. These included pure tone audiometry, conventional tympanometry, and SFI test. RESULTS: In the SFI test, the middle ear dynamic characteristics were measured in terms of the resonance frequency and middle ear mobility. Three distinct categories of middle ear dynamic characteristics were found in patients with otosclerosis, i.e., high stiffness, normal stiffness, and low stiffness middle ear status. On comparison of the results of SFI with conventional tympanometry, a significantly higher percentage of abnormal stiffness was found when using the SFI test than that when using conventional tympanometry. CONCLUSIONS: The present findings confirm the advantage of the SFI test over conventional tympanometry in detecting middle ear status and mechanics in patients with otosclerosis. Moreover, different middle ear dynamic characteristics in patients with otosclerosis are most likely to be related to the different stages of the pathological changes.

Acoustic Impedance Tests↗
PubMed2002

Morphological changes in canine lungs perfused with modified Euro-Collins solution.

OBJECTIVE: To investigate the structural changes in canine lungs perfused with modified Euro-Collins solution (mECS), thus providing insight into the preservation of the donor lung tissue for transplantation. METHODS: Six dogs were anesthetized and pulmonary perfusion with mECS (4 degrees Celsius) was performed before the lungs were isolated thereafter and stored at 4 to 8 degrees Celsius for 30, 60, 120, 180, 240 min respectively, after which tissue samples of the donor lung were taken for morphological observation with both light and transmission electron microscope. RESULTS: Immediately after reperfusion, the pulmonary tissues exhibited clear and intact structures,showing that mitochondrion swelled slightly in the alveolar epithelial cells (AECs). Mild edema occurred in the alveolar wall and the tissues around the veins at 30 min after preservation, which exacerbated to dilapidation of the alveolar wall and obvious tumefaction of the mitochondrion in the AECs at 60 min. At 180 min, rupture of alveolar wall and emergence of the alveolus was observed at 120 min, and a few pulmonary bullae were formed, the AECs (I) of which presented vacuolar changes in the cytoplasma and mitochondrion, with disappearance of the tiny villus of the AECs (II) at 240 min. CONCLUSION: Within 4 h of preservation in mECS, the pulmonary tissues do not undergo obvious changes as signs of injury, which, however, may not be the case after longer preservation.

Animals↗