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Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 361 records · Page 20Linked to original sources
PubMed2000

The changes of TGF-alpha, TGF-beta 1 and basic FGF messenger RNA expression in rabbit cornea after photorefractive keratectomy.

OBJECTIVE: To study the mechanism of haze formation and investigate the expression changes of transforming growth factor-alpha (TGF-alpha), transforming growth factor-beta 1(TGF-beta 1) and basic fibroblast growth factor (bFGF) mRNA in corneal epithelium and stroma after photorefractive keratectomy (PRK). METHODS: Sixteen white rabbits were randomly divided into 4 groups, and PRK was performed on each eye of 12 rabbits. The haze formation was examined under a slit-lamp microscope at the 1st, 2nd and 3rd month after PRK, and the expressions of TGF-alpha, TGF-beta 1 and bFGF mRNA were detected with in situ hybridization. RESULTS: The corneal haze formed at the 1st month after PRK. The most prominent haze formation was observed at the 2nd month, and declined gradually at the 3rd month after ablation. TGF-alpha mRNA expression was presented on the normal corneal epithelium and not on the corneal stroma. TGF-beta 1 and bGFG mRNA were expressed by both corneal epithelium and stroma. The capacities for cornea tissue expression of three growth factors mRNA increased after PRK, and the peaks appeared on the 1st, 2nd month. The extent for expressions of three growth factors related proportionally to the haze formation. CONCLUSION: Three growth factors took part in promoting corneal wound healing after PRK, and might contribute to corneal haze formation and development.

Animals↗
PubMed2000

A study of toxic effect of mitomycin C on cultured bovine trabecular meshwork cells.

PURPOSE: To explore the toxicity of Mitomycin C (MMC) on trabecular meshwork cells. METHODS: Bovine trabecular meshwork cells were cultured in vitro and exposed to MMC of different concentrations. The cellular morphology, ultrastructure, mortality and phagocytosis was studied with light microscopy, transmission electron microscopy and methods of Wright's stain, etc. RESULTS: It was found that the toxic effect of MMC on the cells was in a dose-dependent mode. 1 x 10(-2) and 1 x 10(-3) mg/ml of MMC caused a large part of cells dead, 1 x 10(-4) and 1 x 10(-5) mg/ml of the drug had remarkable killing effect on the cells. 1 x 10(-6) mg/ml of MMC had still a mild toxicity, while 1 x 10(-7) mg/ml of MMC had not any influence on cellular morphology, mortality, and phagocytosis, etc. The safe concentration on bovine trabecular meshwork cells was 1 x 10(-7) mg/ml and the LD50 was between 1 x 10(-3) and 1 x 10(-4) mg/ml. CONCLUSIONS: Refering to previous data, we conclude that conventional clinical-application of MMC might do harm to trabecular meshwork cells.

Animals↗
PubMed2000

[Effect of amniotic membrane on expressions of TGF-beta 1, collagens I, III and fibronectin in rabbit corneal healing after photorefractive keratectomy].

OBJECTIVE: To observed the effect of amniotic membrane transplantation (AMT) on expressions of transforming growth factor-beta 1(TGF-beta 1), collagens I, III and fibronectin (FN) in rabbit corneal healing after photorefractive keratectomy (PRK), and investigate the anti-scarring formation mechanism of AMT. METHODS: Ten rabbits underwent bilateral PRK to correct 8 diopters of myopia. One eye was randomly transplanted with preserved human amniotic membrane, and the other eye served as the control. The expressions of TGF-beta 1, collagens I, III and FN were studied by immunohistochemistry at 4 weeks after operation. RESULTS: The expression of TGF-beta 1 in corneal epithelium and keratocytes and collegans in anterior stroma was significantly less in AMT group than in the control group. The expressions of collagens III and FN in anterior stroma of ablation area were also significantly less in AMT group than in the control group. The staining of collagen I had no significant difference between the AMT group and the control group. CONCLUSION: The expressions of TGF-beta 1, collagens III and FN can be suppressed by amniotic membrane after PRK. These data suggest that part of the anti-scarring effect of AMT may be mediated through the suppression of TGF-beta 1, collagens III and FN expression.

Amnion↗
PubMed2000

[Effect of amniotic membrane on filtering bleb after trabeculectomy in rabbit eyes].

OBJECTIVE: To investigate the effects of amniotic membrane on filtering blebs after trabeculectomy. METHODS: Twelve rabbits underwent bilateral trabeculectomies. One eye was randomly sutured preserved human amniotic membrane between the sclera and the scleral flap and the other eye served as the control. The filtering blebs and filtering function were observed at the 1st, 2nd and 3rd week after the operation. The scar development situation between bleb and episclera was observed under the light microscope. RESULTS: The blebs in amniotic membrane group were eminence, effuse and had a good filtering function at the 1st, 2nd and 3rd week after the operation. The blebs in control group were cicatrized and had a bad filtering function. Histological observation showed no scar development, less fibroblast cell and more inflammatory cells infiltration at the site of trabeculectomy in amniotic membrane group. On the contrary, the control group showed more fibroplasia and fibroblast hyperplasia. CONCLUSION: Amniotic membrane can reduce the scar, improve filtering function.

Amnion↗
PubMed2000

[Relationships between ankylosing spondylitis and ear disease].

OBJECTIVE: To explore whether patients with ankylosing spondylitis (AS) have hearing loss and the pattern of hearing loss. METHODS: Questionnaire, physical examination of the ear, nose and throat, hearing test and sero-immunity examinations were conducted in 34 patients (68 ears) with AS. RESULTS: Among 34 patients, 11 cases reported decrease in the sound perception, and 24 cases (41 ears, 60.3%) had hearing loss as evidenced by the pure tone audiometry. In those patients with hearing loss, 2 ears with perforation of tympanic membrane showed conductive hearing loss and the remainder 39 ears showed sensorineural hearing loss in which 26 ears (66.7%) experienced high frequency hearing loss. Auditory brainstem responses were normally presented in 26 case, whereas abolished in 1 case (2 ears) with severe hearing loss. Examinations of sero-immunity showed a positive response in HLA-B27, but negative responses in the antinuclear antibody and rheumatoid factor. The percentage of the C-reactive protein increase was 81.8%. Autoantibodies anaginst the inner ear were positive in 9 cases (28.1%). In addition, all other immunological examinations revealed certain changes. CONCLUSION: More than half of the patients with AS had sensorineural hearing loss, particularly in the high frequency range. This hearing loss is paralleled by abnormal immunology and is a local expression of systemic autoimmune disease. Therefore, periodical hearing tests are necessary for these patients.

Adolescent↗
PubMed2000

[The electron microscopic study of AchR and ultrastructure of neuromuscular junction in recurrent laryngeal nerve reinnervation].

OBJECTIVE: The purpose of this study was to observe the distribution of Acetylcholine receptor (AchR) and ultrastructural changes of the neuromuscular junction after laryngeal reinnervation. METHODS: alpha-bungarotoxin-horseradish peroxidase (alpha-BT-HRP) conjugate electron microscopic immunocytochemical methods and computer analysis of intensity of immunocytochemical reaction were applied to observe the distribution and relative quantity of junctional N-AchR. RESULTS: The results showed that the synaptic nerve terminals and presynaptic membrane were segmentally disrupted and almost disappeared completely and were replaced by Schwann's cells at 3 weeks after neurorrhaphy. At 6 weeks, some of the regenerating axons grew to the neuromuscular junctions and all the muscle fibers were reinnervated at 12 weeks. But the original postsynaptic membranes were only partially in contact with the regenerated nerve terminals. These conditions persisted until 18 weeks after neurorrhaphy, when remyelination was found in the vicinity of the neuromuscular junctions. The N-AchR reaction product on the postsynaptic membrane were increased greatly about 1.28 times more than the normal at 3 weeks after neurorrhaphy. The reactive products decreased greatly which was only 0.47% of that in the normal at 6 weeks. It remained low until 12 weeks after neurorrhaphy, which was 0.72% of the normal side. It increased obviously to 0.83 times of normal sides at 18 weeks and didn't changed there after. CONCLUSION: The state of reinnervation determines the quantity of neuromuscular junctional N-AchR.

Animals↗
PubMed2000

[An observation on long-term influence of middle ear bacterial infection on inner ear function and systemic immune reaction].

OBJECTIVE: To understand whether long-term inner ear heat shock response related to heat shock protein(HSP70) caused by middle ear bacterial infection and the potential influence on inner ear function. METHODS: Sixty BALB/c mice were randomly classified into 6 groups including Klebsiella pneumoniae (KP), Staphylococcus aureus, Bacillus pyocyaneus, Bacillus coli, Bacillus proteus and physiological saline control groups. On 135 days after injection, distortion product otoacoustic emissions(DPOAE) was tested and all the samples were collected, which were examined with light and electronic microscopes. HSP70 related molecule expression in inner ear, nuclear factor (NF) kappa Bp65 characterization in mononuclear cell, anti-KP antibody and anti-membranous labyrinth proteins (MLP) were examined. RESULTS: No nuclear transfer of NF kappa Bp65 was observed in any animal. Anti-KP antibody was detected in 30% (3/10) of Staphylococcus aureus group, 29% (2/7) of KP group, 33% (3/9) of Bacillus pyocyaneus group and 10% (1/10) of control group. Anti-MLP antibody was created in 20% (2/10) of Staphylococcus aureus group, 20% (2/10) of KP group, one each in Bacillus pyocyaneus group and control group respectively. Double positive antibody against KP and MLP were found in Staphylococcus aureus group and KP group. When analyzed with Western blot, all the positive bands were small molecules including strongest 26,000-30,000, medium degree 38,000-41,000 and weak 46,000-50,000 except for 68,000 in one case. There was only one significant DPOAE amplification decrease at 1,625 Hz (2f1-f2) in left ear of Bacillus pyocyaneus group and right ear of Bacillus proteus group. No abnormal phenomenon was found in inner ear both under light microscope and electronic microscope. No significant expression of HSP70 was observed in inner ears. CONCLUSION: No long-term heat shock response related to HSP70 existed in the inner ear and the immune inner ear damage may be caused by multiplefactors.

Animals↗
PubMed2000

[Interactions between domains within the NH2- and COOH-terminal fragments of presenilins].

OBJECTIVE: To analyze the interactions between domains within the NH2- and COOH-terminal regions of presenilins. METHODS: The various constructions corresponding to NH2-terminal fragment (NTF) and COOH-terminal fragment (CTF) derivatives of presenilin 1 (PS1) and presenilin 2 (PS2) were generated by RT-PCR, and their interactions were assayed by yeast two-hybrid system. RESULTS: Domains within the NH- and COOH-terminal fragments of presenilins could directly interact with each other, and therefore form high molecular weight complex. The interaction site between domains within PS1 located at amino acid 361-447 of PS1 CTF, without the involvement of other partners. Similar interaction was not observed between PS11-360 and PS2341-448, PS2(1)-340 and PS1(361)-467. CONCLUSIONS: Intramolecular interaction between domains within the NH2- and COOH-terminal regions of presenilins may be critical to the folding and assembly of mature PS molecules.

Binding Sites↗
PubMed2000

[The identification and cloning of human ubiquitin binding enzyme cDNA].

OBJECTIVE: To identify and clone the gene encoding human ubiquitin binding enzyme and study its expression spectrum. METHODS: According to the sequence of human EST, which is highly homologous to the mouse ubiquitin conjugating enzyme (E2), primers used for library screening were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by making use of bioinformatics and its expression spectrum was studied by using multiple-tissue Northern blot. RESULTS: Two cDNA clones encoding human ubiquitin conjugating enzyme were isolated and identified. Both containing the ubiquitin conjugating domain, they were 88% identical in amino acid sequences and found to be isoforms of each other with only an exon excised from the short sequence. They belonged to a highly conserved, and widely expressed E2 enzyme family. Northern blot showed that they were expressed exclusively in heart, placenta, and pancreas while no transcripts could be detected in brain, lung, liver, skeletal muscle, or kidney. CONCLUSIONS: The gene encoding human ubiquitin binding enzyme is expressed under both temporal and spatial control. As a key enzyme in the degradation of proteins, ubiquitin conjugating enzymes play a central role in the expression regulation on the level of post-translation.

Amino Acid Sequence↗
PubMed2000

Anti-human platelet tetraspanin (CD9) monoclonal antibodies induce platelet integrin alphaIIbbeta3 activation in a Fc receptor-independent fashion.

OBJECTIVE: This study characterized the activation of platelet integrin alphaIIbbeta3 induced by two anti-human platelet tetraspanin monoclonal antibodies (mAbs), HI117 and SJ9A4. METHODS: Using 125I-labeled human fibrinogen(Fg), specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured as indication of activation of platelet integrin alphaIIbbeta3 by the two mAbs. RESULTS: HI117 and SJ9A4 (10 microg/ml and 20 microg/ml) induced evident specific Fg binding to human platelets, suggesting that the two mAbs evoked activation of platelet integrin alphaIIbbeta3. Further study indicated that HI117 and SJ9A4 induced integrin alphaIIbbeta3 activation independent of platelet Fc-receptors, and that HI117 and SJ9A4-induced integrin alphaIIbbeta3 activation was inhibited by sphingosing, aspirin, apyrase, and/or PGI2. CONCLUSION: The anti-platelet tetraspanin (CD9) mAbs, HI117 and SJ9A4, can induce platelet integrin alphaIIbbeta3 activation independent of Fc-receptor. Three signaling pathways, i.e. thromboxane, secreted ADP, and cAMP pathways may be involved in the process, with protein kinase C activation presumably being the common step of the three pathways.

Antibodies, Monoclonal↗
PubMed2000

[Self-assembly of nano-structured silver particle and its surface-enhanced Raman spectroscopic application].

Planar arrays of nano-structured silver particle were self-assembled on poly-lysine modified glass surfaces. SEM characterization indicates that silver particles were assembled as a sub-monolayer. A comparison of the UV/Vis spectra of silver colloid and the arrays demonstrates that the poly-lysine layer showed size selectivity for the self-assembling silver particles. Surface-enhanced FT-Raman spectrum of methylviolegen on the array reveals that Raman scattering in near IR region was mainly enhanced via a chemical enhancement mechanism.

Colloids↗
PubMed2000

[Study on optical properties and synthesis of nanosized GeO2-SiO2 glasses].

The compound material of nm size particles GeO2-SiO2 was synthesized through hydrolysis of Si(OC2H5)4 and GeCl4 with pH-2. A heat-treatment was carried out for samples at 100-1,200 degrees C in air. Its optical property was determined by UV-Vis spectrum. We have found that the absorption edge of spectrum shifted progressively to longer wavelengths. The quantum size effect of nanocrystals appears because crystals grow and the energy of optical band gap reduces due to the influence of temperature. By the analysis of X-ray diffraction we have observed the process in which the structure of particles changed from disorder into order, and the particles with size 5-10 nm came into obviously as temperature increased until 1,100 degrees C.

Gels↗
PubMed2000

[A preliminary study on fimbriae subunits and molecular weight of actinomyces viscosus 5951]

OBJECTIVE:To preliminarily analyse the subunits and molecular weight of fimbriae of actinomyces viscosus 5951.METHODS:To do the immunoblotting test of the only II fimbriae type of mutant strain of T14V.RESULTS:It showed that there was only one 31ku band,which indicated that the fimbriae of actinomyces viscosus 5951 was composed of the same subunits of 31ku molecular weight. CONCLUSION:According to the previous reports and results of present study,the molecular weight of fimbriae of actinomyces viscosus 5951 was speculated to be 124ku and the fimbriae was composed of 4 same subunits.

Journal Article↗
PubMed1999

Preparation of Shell-Core Cu(2)O-Cu Nanocomposite Particles and Cu Nanoparticles in a New Microemulsion System.

Shell-core Cu(2)O-Cu nanocomposite particles and metal Cu nanoparticles are synthesized in a new microemulsion system which consists of saturated Cu(2+) salt aqueous solution dispersed in isopropanol and stabilized by polyvinylalcohol (PVA). The size of the composite particles and the thickness of the Cu(2)O shell layer can be controlled by the volume ratio of isopropanol to H(2)O (the ratio is defined as R). When R >/= 1000, it is available to obtain metal Cu nanoparticles. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

STEAP: a prostate-specific cell-surface antigen highly expressed in human prostate tumors.

In search of novel genes expressed in metastatic prostate cancer, we subtracted cDNA isolated from benign prostatic hypertrophic tissue from cDNA isolated from a prostate cancer xenograft model that mimics advanced disease. One novel gene that is highly expressed in advanced prostate cancer encodes a 339-amino acid protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This structure suggests a potential function as a channel or transporter protein. This gene, named STEAP for six-transmembrane epithelial antigen of the prostate, is expressed predominantly in human prostate tissue and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. Immunohistochemical analysis of clinical specimens demonstrates significant STEAP expression at the cell-cell junctions of the secretory epithelium of prostate and prostate cancer cells. Little to no staining was detected at the plasma membranes of normal, nonprostate human tissues, except for bladder tissue, which expressed low levels of STEAP at the cell membrane. Protein analysis located STEAP at the cell surface of prostate-cancer cell lines. Our results support STEAP as a cell-surface tumor-antigen target for prostate cancer therapy and diagnostic imaging.

Amino Acid Sequence↗
PubMed1999

Folding of a model three-helix bundle protein: a thermodynamic and kinetic analysis.

The kinetics and thermodynamics of an off-lattice model for a three-helix bundle protein are investigated as a function of a bias gap parameter that determines the energy difference between native and non-native contacts. A simple dihedral potential is used to introduce the tendency to form right-handed helices. For each value of the bias parameter, 100 trajectories of up to one microsecond are performed. Such statistically valid sampling of the kinetics is made possible by the use of the discrete molecular dynamics method with square-well interactions. This permits much faster simulations for off-lattice models than do continuous potentials. It is found that major folding pathways can be defined, although ensembles with considerable structural variation are involved. The large gap models generally fold faster than those with a smaller gap. For the large gap models, the kinetic intermediates are non-obligatory, while both obligatory and non-obligatory intermediates are present for small gap models. Certain large gap intermediates have a two-helix microdomain with one helix extended outward (as in domain-swapped dimers); the small gap intermediates have more diverse structures. The importance of studying the kinetic, as well as the thermodynamics, of folding for an understanding of the mechanism is discussed and the relation between kinetic and equilibrium intermediates is examined. It is found that the behavior of this model system has aspects that encompass both the "new" view and the "old" view of protein folding.

Algorithms↗
PubMed1999

Association of Nafion with Polypyrrole Nanoparticles in a Hydrophilic Polymer Network: Effects on Proton Transport.

Proton-conducting polymer composites containing perfluorosulfonic polymer (Nafion) and polypyrrole (PPy) nanoparticles in a polyacrylamide network, P(AAM-MBAM), were synthesized as proton-conducting electrolytes. An investigation into the assembling of Nafion polymer molecules as well as the colloidal PPy-Nafion complexes in the P(AAM-MBAM) network was carried out on the basis of DSC and XRD analysis. It was found that the proton conductivity of the composites was largely affected by the occurrence of the free volume between the P(AAM-MBAM) network and Nafion polymer as well as the concentration of the PPy-Nafion complexes in the composites according to the measurements of the electrical resistance and the frequency-dependent impedance. Copyright 1999 Academic Press.

Journal Article↗