PubMed Health⌕ Search

Biomedical subjects

Y Liu

Publications and source records attributed to Y Liu.

At least 703 records · Page 39Linked to original sources
PubMed2001

[Study on mutations in the connexin 26 gene among Chinese with nonsyndromic hearing loss].

OBJECTIVE: To study the relation between nonsyndromic hearing loss in Chinese and mutations in connexin 26 (Cx 26) gene and to explore the pathogenic mechanism. METHODS: One hundred and thirty-eight individuals from thirty-five pedigrees with nonsyndromic hearing loss, 99 children with sporadic nonsyndromic hearing loss and 100 normal adults as control were collected in present studies. The Cx 26 coding sequence was screened by single strand conformational polymorphism (SSCP) and analyzed by direct sequencing when SSCP shifts were observed. RESULTS: Five SSCP shifts in 2 pedigrees were observed. Homozygous deletion C at position 233-235 of Cx 26 cDNA, which resulted in frameshift mutation, was found in 2 pedigrees with nonsyndromic hearing loss. CONCLUSION: The hot-spot mutations of Cx 26 gene in Chinese with nonsyndromic hearing loss may be different from other ethnic groups. The 233-235 delC homozygous mutation of Cx 26 cDNA can result in autosomal recessive nonsyndromic hearing loss in Chinese population.

Adult↗
PubMed2001

[Postlaryngectomy peristomal recurrence].

OBJECTIVE: To study the etiopathology, diagnosis and management of peristomal recurrence after laryngectomy, and the prevention of peristomal recurrence. METHODS: Retrospective analysis of clinical management and outcomes of 16 cases of peristomal recurrence. RESULTS: The subglottic extension of laryngeal cancer and peritracheal metastasis may result in peristomal recurrence. The stomal resection with mediastinal dissections and the use of the pectoralis major myocutaneous flap were done. The survival period of 11 cases surgically treated was longer than that of 5 cases irradiated or untreated. CONCLUSION: Surgical management would improve the survival, but overall prognosis is dismal and attention should be focused on prevention. It is evident that early diagnosis of stomal recurrences will yield good results.

Aged↗
PubMed2001

[Intact-bridge tympanomastoidectomy procedure: a reasonable option in the surgery of chronic otitis media and mastoiditis with cholesteatoma and/or granulation tissue].

OBJECTIVE: To study and evaluate a surgical option for the treatment of otitis media and mastoiditis with cholesteatoma and/or granulation tissue. METHODS: The procedure is called intact-bridge tympanomastoidectomy (IBM). There are some modifications for the treatment of patients suffered from chronic otitis media and mastoiditis with cholesteatoma and/or granulation tissue. The features of IBM include: 1. the aditus, mastoid and attic opened and the intractable pathological tissues eradicated thoroughly. 2. the posterior tympanal space opened through the facial recess if necessary. 3. a widened middle ear space by lowering bony bridge established. 4. the adults blocked. 5. immediate or staging tympanoplasties conducted according to the conditions of mucosa in the tympanum. RESULTS: The modified IBM procedure was performed on 62 ears from 61 cases. The follow-up has been 12-38 months and more than two years in 51 ears. The dry ear was obtained within 5-13 weeks with an average of 6 weeks. In 24.2% of ears the air-bone gap(ABG) was 20dB HL or less and within 21-30 dB HL in 41.9% of ears, the ABG over 31 dB HL was 16.1%. CONCLUSION: Our results indicate that IBM procedure fulfills the desired purposes of both open- and close-cavity techniques, the thorough eradication of diseased tissue allow to get a dry ear and restoration of hearing. IBM, therefore, is a reasonable choice for the surgery of otitis media and mastoiditis with cholesteatoma and/or granulation tissue.

Adolescent↗
PubMed2001

Bioactivity of bioresorbable osteosynthetic devices made of hydroxyapatite/poly-DL-lactide composites: an experimental study.

AIM: To investigate the bioactivity of the self-designed biodegradable osteosynthetic devices made of resorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) composites. METHOD: Forty-three rabbits with a transverse transcondylar osteotomy of the distal femur were fixed intramedullary by a HA/PDLLA rod, the duration of follow-up were 3, 6, 12, 24 and 36 weeks. Histological, scanning electron microscopic (SEM), energy dispersive X-ray (EDX) and biomechanical analyses were done. RESULTS: Active new bone formation and direct bone-bonding were seen at the bone-implant interface. Generous apatite crystals deposited and grew on the surface of the composites at 3 approximately 6 weeks postoperation. The interfacial shear strength increased significantly. CONCLUSION: Through the incorporating of resorbable HA microparticles, specific bone-bonding and active osteogenic capacity is introduced. This kind of bioactivity, together with other properties such as sufficient mechanical strength, enhanced biocompatibility and radiopacity, which are intrinsically unobtainable in totally resorbable polymer/polymer systems, make the HA/PDLLA composites become a desirable material for the internal fixation of cancellous bone.

Absorbable Implants↗
PubMed2001

[6A8 alpha-mannosidase catalyzes p-nitrophenyl-alpha-D-mannopyranoside].

OBJECTIVE: To confirm the alpha-mannosidase nature of the protein encoded by 6A8 cDNA. METHODS: 1) To construct a full-length 6A8 cDNA based on the three cloned DNA fragments by means of gene recombinant technique; 2) To insert the 6A8 cDNA into eukaryotic expression vector pCDI; 3) To transfect the recombinant pCDI-6A8 into COS-7 cells; 4) To characterize the nature of the protein encoded by 6A8 cDNA by means of enzymic activity assay and Western blotting assay. RESULTS: The constructed 6A8 cDNA was the right cDNA in sequence. The enzymetic activity of the homogenate of COS-7 cells transfected with pCDI-6A8 was 3-4 times higher than that of the cells transfected with the mock or the wild cells. The enzymetic reaction could not be inhibited by swainsonine. Western blot showed a band of 120,000 recognized by mAb 6A8. The band in the cells transfected with pCDI-6A8 cDNA was much darker than that in the cells transfected with the mock or in the wild cells. CONCLUSION: The protein encoded by 6A8 cDNA is a kind of alpha-mannosidase, which belongs to type II alpha-mannosidase.

Animals↗
PubMed2001

[Neocartilage formation in vitro using transduced mesenchymal stem cells cultured on biomimetic biodegradable polymer scaffolds].

OBJECTIVE: To investigate the effect of transforming growth factor (TGF) beta 1 gene transfection on the growth of mesenchymal stem cells(MSCs) and to evaluate a new biomimetic biodegradable polymer as scaffolds for applications in articular cartilage tissue engineering. METHODS: Principles of tissue engineering were combined organically with principles of gene therapy to produce cultured periosteum-derived MSCs transduced with the full-length rat TGF-beta 1 cDNA in vitro. These cells were then seeded onto three-dimensional porous poly-DL-lactide scaffolds modified with poly-L-lysine that mimicked cell-binding domains found on natural extracellular matrix to promote specific cell adhesion. The adhesion, proliferation, and differentiation of the transfected MSCs were examined with scanning electron microscope within 2 weeks. RESULTS: All cells adhered to the biomimetic matrices well, but more cartilage-like tissue was formed for TGF-beta 1 gene modified MSCs/scaffolds composites than for the control groups. Transfer of gene encoding TGF-beta 1 to MSCs promoted its proliferation and differentiation significantly. CONCLUSIONS: The TGF-beta 1 gene transduced MSCs/biomimetic matrix composites used in this study was the first attempt to apply the principles of molecular tissue engineering for articular cartilage repair. This new molecular tissue engineering approach could be of potential benefit to repair damaged articular cartilage, especially in osteoarthritis. The new biomimetic biodegradable polymer matrices modified with biomolecules not only have good structural compatibility, but also have better interfacial compatibility and bioactivity, and can be used as scaffolds for articular cartilage tissue engineering.

Animals↗
PubMed2001

[Expression of hepatitis E virus ORF3 gene fragment in baculovirus system and its immunological character].

OBJECTIVE: To express hepatitis E virus (HEV) ORF3 protein by baculovirus system and provide basis for immunological character research. METHODS: Hepatitis E Virus ORF3 gene fragment was obtained by RT-PCR, ligated with vector pThioHisA for sequencing and then inserted into transfected vector pVL1393 to construct recombinant plasmid. Mediated by Lipofectin Reagent, the recombinant vector and baculovirus linearized DNA (BaculoGold) co-transfected insect cell Sf9 to make recombinant baculovirus. Expressed ORF3 was analyzed for its immunological character by Western blotting, and immunized Kunming Mice. RESULTS: Recombinant ORF3 protein could be recognized by the known positive serum and promoted organism to produce HEV-specific antibody. CONCLUSIONS: Recombinant baculovirus can express effectively HEV ORF3, which has HEV specific immunogenic character.

Animals↗
PubMed2001

[Purification and immunological characterization of hepatitis E virus recombinant chimeric antigen encoded by ORF2 fragments and ORF3].

OBJECTIVE: To study immunological characteristics of recombinant chimeric HEV antigen. METHODS: Constructed recombinant plasmids pThioHisORF(2.1 + 2.2 + 3), which contains three HEV antigen gene fragments (ORF2.1:6287-6403nt, ORF2.2:6743-7126nt, ORF3), was transformed into E. coli and induced with IPTG. Expressed product P(2.1 + 2.2 + 3) existed in inclusion bodies, was purified by denature SP Sepharose FF cation exchange chromatography. Rabbits and rats were immunized with renatured P(2.1 + 2.2 + 3). The level of IgG in sera from experimental animals and clinical patients were examined with P(2.1 + 2.2 + 3) by ELISA. The characteristics of IgG of immunized animals interacted with recombinant antigen expressed by baculovirus system as well as recombinant chimeric antigen interacted with clinical patients sera were evaluated by Western-blotting. RESULTS: High titer of IgG antibodies, 1:25,600 in rabbits and 1:12,800 in rats, were detected after immunized with P(2.1 + 2.2 + 3). Furthermore, recombinant antigen expressed by baculovirus system was specifically recognized by IgG of experimental animal immunized with P(2.1 + 2.2 + 3), and the purified recombinant chimeric antigen P(2.1 + 2.2 + 3) was specifically reacted with the IgG of clinical patients. CONCLUSIONS: Recombinant chimeric antigen appears a promising strategy for detection of and prevention from HEV infection.

Animals↗
PubMed2001

[Comparisons of two ultraviolet-vacuum ultraviolet radiation scales].

The ultraviolet-vacuum ultraviolet emission standards including high temperature argon wall-stabilized arc and synchrotron radiation were introduced. The spectral radiometric characteristics of an argon wall-stabilized arc and a deuterium lamp calibrated by synchrotron radiations were studied as ultraviolet-vacuum ultraviolet radiation scales. With the spectroradiometris system of high precision established by us, the comparison of scales between the argon wall-stabilized arc and the synchrotron radiations in the 165-300 nm range has shown agreement to within +/- 5%.

Argon↗
PubMed2001

[Study of the charge transfer reaction between clotrimazolum and alizarin red].

The charge transfer reaction between clotrimazolum and alizarin red was studied spectrophotometrically. The reaction was achieved with good results in water-acetone solution. The apparent molar absorptivity is 8.7 x 10(3) L.mol-1.cm-1 at 525 nm. The Beer's law was obeyed in the range of 0-100 micrograms.mL-1 of clotrimazolum. The composition of the complex is 1:1. The proposed method has been applied successfully to the determination of clotrimazolum tablets.

Anthraquinones↗
PubMed2001

[On the characteristics of velocity modulation laser spectroscopy].

The technical properties of velocity modulation laser spectroscopy were investigated using the spectrum of A2 pi u-X2 sigma g+ (2-0) band of Meinel system of N2+. The dependence of spectral intensity on discharge current, the pressure of the gas mixture and the pump velocity of the vacuum pump were studied. Making uses of the results of these studies, the sensitivity and resolution of the spectrometer are improved by above 3 times, and economized the experimental expenses can be reduced to as 3/4 time as normal, which confirms that the results of this paper is of considerable uses.

Lasers↗
PubMed2001

[Stable high quality luminescent material CaAl4O7:Tb3+, Ce3+].

We had made CaAl4O7:Tb3+, Ce3+ samples by sintering the sample at 1,300 degrees C in reduction environment N2 + 5% H2. Emission lines corresponding to the 3D4 to 7Fj(J = 6,5,4,3) optical transitions of the Tb2+ ions were observed at 485,545,590 and 620 nm respectively. The particle size of the sample was controlled to less that 1 micron. The lattice of the sample was rather regular in atomic scale and showed very good quality. CaAl4O7:Tb3+, Ce3+ materials can reduce structure uncertainty of the host and remain typical optical properties of the Tb3+ emitting center.

English Abstract↗
PubMed2001

[Assignments of FIR-LMR spectra of CF X 2Pi (nu = 1) and MIR-LMR spectra of NO X 2Pi (nu = 1<--0)].

According to the theories of Zeeman effect and the principle of laser magnetic resonance (LMR), a method and model for the analysis of the laser magnetic resonance spectra were developed and successfully employed to assign the FIR-LMR spectra of CF X2 Pi (nu = 1) and the MIR-LMR spectra of NO X 2Pi (nu = 1<--0). This work provided an efficient and accurate approach for primary analysis of the LMR spectra of novel radicals.

English Abstract↗
PubMed2001

[Observation of plasma levels of beta-endorphin in patients with trigeminal neuralgia].

OBJECTIVE: To observe the relationship between plasma levels of beta-endorphin and trigeminal neuralgia. METHODS: During the attacks of trigeminal neuralgia, beta-endorphin levels of plasma from external jugular, cubital fossa vein blood ipsilateral to the pain and contralateral external jugular vein blood were assessed by sensitive radioimmunoassay in 12 cases, after operations the venous blood from the ipsilateral external jugular vein was sampled again, the external jugular vein blood of 12 normal volunteers was collected as control. RESULTS: The plasma levels of beta-endorphin in patients with trigeminal neuralgia were significantly lower than that in normal volunteers (P<0.05). CONCLUSION: The lowered plasma beta-endorphin levels may be an important factor for the development of pain in patients with trigeminal neuralgia, which may result in pain and neurogenic inflammation that can not be controlled in central nervous system and peripheral nerve terminals.

English Abstract↗
PubMed2001

[Survey of caries status of 5-year-old children in Shanghai in 1995].

OBJECTIVE: To determine the caries status of 5-year-old children in Shanghai. METHODS: Use multistage sampling method,stratified sampling and simple random sampling methods. 2 132 5-year-old children were chosen and their DMFTs were examined. Two thirds were done in three downtown districts and the rest in three suburb counties. Each gender occupies half. RESULTS: DMFT in downtown and suburb was 3.46 and 7.37, respectively. Caries prevalence was 71.13% and 92.56%, respectively.The percentage of filling in DMFT was 14.79% and 3.24%, respectively. All this three indices proved to be significantly different between downtown and suburb. CONCLUSION: It is indicated that caries prevalence of deciduous teeth should be lowered both in downtown and suburb areas. Filling percentage should be improved urgently, especially in suburbs. The preventive means should focus on suburbs as well.

English Abstract↗
PubMed2001

[Study on the correlation of the cytokine secreted by the endometrium focus and the microenvironment of the fleument fluid].

OBJECTIVE: To investigate the correlation of endometriotic focus and peritoneal fluid as well as its effect on reproduction. METHODS: Forty-three women with surgical treatment or laproscope with infertility are divided into endometriosis group (24 cases) and normal pelvic group (control group 19 cases) . The pathophysiology of patient' s peritoneal fluid, celiac macrophages and endometriotic cells are analyzed by chemotactic test on monocytes, dot blot hybridize, enzyme linked immunoadsorbent assay and the level of cytoplasmic [Ca2+]i respectively. Meanwhile, the influence of peritoneal fluid and endometriotic cells to sperm motivity as well as the effects to rat embryo cleavage are evaluated. RESULTS: The monocyte moving distance induced by peritoneal fluid in endometriosis group vs. control is (87.2 +/- 9.4) m vs. (51.9 +/- 3.7) microm (P < 0.01). The count of celiac macrophages (1.47 +/- 0.87) x 10(6)/ml vs. (0.67 +/- 0.73) x 10(6)/ml (P < 0.01), The basic expression level of monocyte chamotactic protein-1 (MCP-1) in endometriotic cells is (18.34 +/- 3.95) A. After exposured to IL-1beta and tumor necrosis factor-alpha, the OD of MCP-lmRNA is 56.84 +/- 3.21 A and 41.58 +/- 2.48 A respectively (P < 0.01 ). CONCLUSION: With the influence between endometriotic focus and microenvironment of peritoneal fluid, the level of cytokines expressed by celiac macrophages and endometriotic focus are enhanced, and it can interfere some process in reproduction.

Animals↗
PubMed2001

[Effects of aspiration of airway dead space on blood gases and respiratory mechanics in acute hypercapnia model dogs].

OBJECTIVE: To establish the method of aspiration of airway dead space (ASPIDS) and evaluate the effects of ASPIDS on elimination of CO2 and improvement of ventilation efficiency. METHODS: Using self-designed ASPIDS device, physiological parameters such as PaCO2, P(peak), P(pause), end expiratory carbon dioxide pressure (PaCO2), lung statistic compliance (Cst), respiratory resistance (Re) and hemodynamics in two animal groups of conventional mechanical ventilation (CMV) and hypercapnia (HC) were observed by applying tracheal gas insufflation (TGI 4.0 L/min) and ASPIDS (4.0 L/min). RESULTS: ASPIDS significantly decreased PaCO2 level, enhanced CO2 elimination and maintained PaCO in normal range while decreased VT by 30%, the elimination of CO2 of ASPIDS was superior to that of TGI. ASPIDS significantly decreased airway pressure in both animal groups . P(et)CO2 and Re levels significantly decreased after ASPIDS. ASPIDS showed no influence on Cst, hemodynamics and oxygenation. CONCLUSIONS: The ASPIDS device is a simple and practical adjunct method to mechanical ventilation, it can more effectively decrease PaCO2 than TGI, and maintain lower airway pressure.

Animals↗