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Biomedical subjects

H Zheng

Publications and source records attributed to H Zheng.

At least 109 records · Page 6Linked to original sources
PubMed2001

Experimental study on the effect of perfluorodecalin on rabbit corneas.

PURPOSE: To study the effects of perfluorodecalin on the cornea of the rabbit eyes. METHODS: Perfluorodecalin (0.05 ml/each) was injected into the anterior chambers of eighteen rabbit eyes. Corneal morphology and endothelial cells were monitored clinically by slit-lamp biomicroscope and specular microscope for 26 weeks. Animals were sacrificed in 1st, 2nd, 4th, 10th, 16th, 22nd, and 26th week after injection, respectively, and the corneas were examined under the light microscope. RESULTS: Perfluorodecalin droplets looking like "fish eggs" were found at about 1/4-1/2 of the corneal height in the inferior anterior chamber. Corneal opacification on the area contacted with perfluorodecalin was observed in five eyes five weeks after injection, and all in the 22nd week. Mutton fat KPs in one eye were seen in the 6th week firstly, and in all eyes in the 7th week. Corneal pannus formation in one eye was present in the 4th week, two eyes in the 5th week and three eyes in the 6th week. Retrocorneal fibrous membrane in one eye was detected at the 6th week and 3 eyes at the 7th week respectively. After injection of perfluorodecalin, endothelial cell density was significantly decreased (2,789 +/- 192 vs. 2,341 +/- 658, P < 0.01) and corneal thickness was increased. CONCLUSIONS: Perfluorodecalin injected into anterior chamber can lead to corneal damage and inflammatory reaction.

Animals↗
PubMed2001

Experiment study of effect of perfluorohexyloctane on corneal endothelial cells.

PURPOSE: To investigate the effect of Perfluorohexyloctane (F6H8) on corneal endothelial cells(CEC) of rabbit eyes. METHODS: Fifteen New Zealand white rabbits were divided into two groups: experimental group(F6H8) and control group(BSS). All rabbits underwent anterior chamber injection of 0.15 ml F6H8 or BSS. Slit-lamp biomicroscopy and corneal endothelium photography were performed pre-operatively and postoperatively. Histopathological examination and Transmission electron microscopy(TEM) were done after the rabbits were sacrificed. RESULTS: All the corneas were clear. Since 4 weeks after operation, the endothelial cells were markedly irregular in size and shape and the number of endothelial cells was markedly decreased. Multilayered retrocorneal membranes(RCM) grew gradually 2 weeks after surgery. Vacuolar degeneration was seen in some endothelial cells. Nuclear degeneration and edema of plasma were seen in TEM. CONCLUSION: Corneal endothelial cell degenerated after contacting with F6H8 for 2-4 weeks. As a silicone solvent, it should be removed completely after injection. We don't recommend it to be used as a new intraocular temponade.

Animals↗
PubMed2001

[The inhibitory effect of mitomycin C applied by intracapsular method on rabbit lens epithelial cells: an experimental study of after-cataract].

OBJECTIVE: To study the inhibitory effect of Mitomycin C applied by intracapsular infusion method on rabbit lens epithelial cells and its intraocular toxicity. METHODS: 0.2 ml Mitomycin C with different concentration (0.1 mg/ml, 0.2 mg/ml, 0.4 mg/ml) was injected into the capsular bags of the rabbits' lens during the hydrodissection of phacoemulsification. The drug was exposed to the lens epithelial cells directly and transiently. In the two-month follow-up after the operation, the posterior capsule opacification and the change of intraocular pressure were observed and compared between the control group and the experimental group; the histopathologic and the ultrastructural changes were also observed. RESULTS: For clinical study in the rabbit, the posterior capsule opacification only appeared in the control group two weeks after the operation. Four weeks after the operation, the posterior capsular opacification in the eyes of experimental group was not so obvious as that of the control group. The higher the concentration of the drugs, the less the posterior capsule opacification was shown. There was no obvious difference in the postoperative inflammation between the control group and the low, middle-concentration experimental group. Slight toxic reaction was shown on the rabbits' eyes of the high-concentration experimental group in the early stage after the operation. The histopathologic examination showed that the proliferation of lens epithelial cells in the control group was more obvious than that in the experimental group. Mitomycin C could cause the degeneration of lens epithelial cells. The degree of degeneration was related to the drug's concentration. The ciliary bodies of the rabbits' eyes in the high-concentration experimental group were infiltrated by inflammatory cells and bled slightly. CONCLUSION: Mitomycin C can inhibit the proliferation of lens epithelial cells effectively. Its intensity is related to the drug's concentration. It's a safe and effective drug in the prevention of after-cataract when the concentration of 0.1-0.2 mg/ml was applied in the capsular bag.

Animals↗
PubMed2001

[The expression of growth factors in filtering area following sclerectomy and the interaction between growth factors and interferon].

OBJECTIVE: To study the expression of beta-Fibroblastic Growth Factor (bFGF) and Transforming Growth Factor beta 1 (TGF beta 1) in filtering area following sclerectomy and the interaction between growth factors and interferon alpha-2b (IFN alpha-2b). METHODS: Immunohistochemical technique were applied to test the expression bFGF and TGF beta 1 in frozen sections of filtration area following sclerectomy on postoperative day three, five, seven and 14 in white rabbits, respectively. 16 eyes of eight rabbits in all were randomly and equally divided into two groups. The experimental eyes had subconjunctivally been administered IFN alpha-2b 5 x 10(5) IU 0.2 ml each time at filtering bleb following operation whereas the control eyes hadn't taken. RESULTS: In control group, positive cell and substance expressing bFGF and TGF beta 1 on postoperative day three were revealed in the filtration area, on postoperative day five and seven, they were gradually increased. On the postoperative day 14, all significant cells and substance markly decreased. In experimental group only small amount of positive cell and bFGF or TGF beta 1-expressing substance were sparely distributed in the filtration area. CONCLUSION: The filtration area after glaucoma filtering surgery was "bathed" in growth factors such as bFGF and TGF beta 1 which well-known play an important role in stimulating wound healing response, IFN alpha-2b had an inhibitory effect on bFGF or TGF beta 1 expression in wound environment.

Animals↗
PubMed2001

[The cluster analysis of trace elements in fructus cnidii from different region].

The contents of trace elements in Fructus Cnidii from different region were assayed by atom absorption spectrum and analyzed by cluster analysis methods. The results showed the contents of trace elements from different regions were different, which had some relativity with habitats, but should be further studied.

Cluster Analysis↗
PubMed2001

[Detection of GABAA alpha 2 mRNA in rat vestibular end organ with in-situ hybridization].

OBJECTIVE: To investigate the effect of the gamma-aminobutyric acid (GABA) on rat vestibular end organ. METHODS: In the rat inner ear paraffin slides, GABAA receptor alpha 2 subunit mRNA in vestibular end organ has been detected with in-situ hybridization. Digoxigenin-GABAA alpha 2 cDNA prob (549 base pair), Anti-Digoxigenin-AP (Fab fragments) and BM Purple AP Substrate (precipitating) have been used. RESULTS: GABAA receptor alpha 2 subunit mRNA has been found in all vestibular ganglion cells and nerve ending surrounding type I hair cells in rat's cristae ampullaris. GABAA alpha 2 has not been found in hair cells and supporting cells. As a positive control, GABAA alpha 2 mRNA has been found in Purkinje cells and granule cells in rat's cerebellum. GABAA alpha 2 has not been found in OMP negative control, non-prob negative control and non-anti-digoxingenin control in inner ear and cerebellum slides. CONCLUSIONS: GABAA alpha 2 receptor has been found in vestibular afferent nerve endings and vestibular ganglion cells. It strongly indicates that GABA is an afferent nerve transmitter in the vestibular end organ and plays an important role in the vestibular afferent nerve transmission.

Animals↗
PubMed2000

Antitumor properties of influenza virus vectors.

We are investigating the potential use of influenza virus vectors expressing selected tumor-associated antigens (TAAs) as therapeutic agents in anticancer strategies. Previously, we have shown that recombinant influenza viruses expressing a model TAA mediated the regression of established pulmonary metastases in mice through the induction of cytotoxic T-cell responses (N. P. Restifo et al., Virology, 249: 89-97, 1998). We have now expanded these observations in the mouse model using survival as the end point of the assay. Animals with a high tumor burden showed extended survival times when treated with a recombinant influenza virus expressing a TAA, but they finally succumbed to death. Death was associated with the presence of a small number of large tumors in lungs. Interestingly, these tumors were found to express undetectable levels of the TAAs because of a down-regulation in the TAA-specific mRNA levels. On the other hand, mice with five times lower tumor burden showed complete tumor regression and survival for >6 six months when treated with the recombinant virus. These animals showed protection against a tumor challenge 6 months after treatment. Our results suggest that recombinant influenza viruses may be useful as therapeutic agents for the prevention and treatment of cancers with known TAAs.

Animals↗
PubMed2000

Negative cross-talk between p53 and the glucocorticoid receptor and its role in neuroblastoma cells.

The tumour suppressor p53 and the glucocorticoid receptor (GR) respond to different types of stress. We found that dexamethasone-activated endogenous and exogenous GR inhibit p53-dependent functions, including transactivation, up- (Bax and p21(WAF1/CIP1)) and down- (Bcl2) regulation of endogenous genes, cell cycle arrest and apoptosis. GR forms a complex with p53 in vivo, resulting in cytoplasmic sequestration of both p53 and GR. In neuroblastoma (NB) cells, cytoplasmic retention and inactivation of wild-type p53 involves GR. p53 and GR form a complex that is dissociated by GR antagonists, resulting in accumulation of p53 in the nucleus, activation of p53-responsive genes, growth arrest and apoptosis. These results suggest that molecules that efficiently disrupt GR-p53 interactions would have a therapeutic potential for the treatment of neuroblastoma and perhaps other diseases in which p53 is sequestered by GR.

Apoptosis↗
PubMed2000

Ruthenium(II) ammine and hydrazine complexes with [N(Ph2PQ)2]- (Q = S, Se) ligands.

Reactions of coordinatively unsaturated Ru[N(Ph2PQ)2]2(PPh3) (Q = S (1), Se (2)) with pyridine (py), SO2, and NH3 afford the corresponding 18e adducts Ru[N(Ph2PQ)2]2(PPh3)(L) (Q = S, L = NH3 (5); Q = Se, L = py (3), SO2 (4), NH3 (6)). The molecular structures of complexes 2 and 6 are determined. The geometry around Ru in 2 is pseudo square pyramidal with PPh3 occupying the apical position, while that in 6 is pseudooctahedral with PPh3 and NH3 mutually cis. The Ru-P distances in 2 and 6 are 2.2025(11) and 2.2778(11) A, respectively. The Ru-N bond length in 6 is 2.185(3) A. Treatment of 1 or 2 with substituted hydrazines L or NH2OH yields the respective adducts Ru[N(Ph2PQ)2]2(PPh3)(L) (Q = S, L = NH2NH2 (12), t-BuNHNH2 (14), l-aminopiperidine (C5H10NNH2) (15); Q = Se, L = PhCONHNH2 (7), PhNHNH2 (8), NH2OH (9), t-BuNHNH2 (10), C5H10NNH2 (11), NH2NH2 (13)), which are isolated as mixtures of their trans and cis isomers. The structures of cis-14 and cis-15 are characterized by X-ray crystallography. In both molecular structures, the ruthenium adopts a pseudooctahedral arrangement with PPh3 and hydrazine mutually cis. The Ru-N bond lengths in cis-14.CH2Cl2 and cis-15 are 2.152(3) and 2.101(3) A, respectively. The Ru-N-N bond angles in cis-14.CH2Cl2 and cis-15 are 120.5(4) and 129.0(2) degrees, respectively. Treatment of 1 with hydrazine monohydrate leads to the isolation of yellow 5 and red trans-Ru[N(Ph2PS)2]2(NH3)(H2O) (16), which are characterized by mass spectrometry, 1H NMR spectroscopy, and elemental analyses. The geometry around ruthenium in 16 is pseudooctahedral with the NH3 and H2O ligands mutually trans. The Ru-O and Ru-N bond distances are 2.118(4) and 2.142(6) A, respectively. Oxidation reactions of the above ruthenium hydrazine complexes are also studied.

Journal Article↗
PubMed2000

The forkhead transcription factor UNC-130 is required for the graded spatial expression of the UNC-129 TGF-beta guidance factor in C. elegans.

Secreted proteins required for cellular movements along the circumference of the body wall in Caenorhabditis elegans include UNC-6/netrin and the novel TGF-beta UNC-129. Expression of these proteins is graded along the dorsoventral (D/V) axis, providing polarity information to guide migrations. Here we show that the graded expression of UNC-129 in dorsal but not ventral body muscles depends on unc-130, which encodes a Forkhead transcription factor. The phenotype of unc-130 mutants closely mimics the reported effects of ectopically expressing unc-129 in both dorsal and ventral body muscles (). This fits our present finding that unc-130 cell autonomously represses unc-129 expression in the ventral body muscles. Thus the cell-specific effects of unc-130 on ventral, but not dorsal, body muscle expression of unc-129 accounts for the D/V polarity information required for UNC-129-mediated guidance. Genetic interactions between unc-130 and other guidance genes show that several molecular pathways function in parallel to guide the ventral to dorsal migration of distal tip cells (DTCs) and axonal growth cones in C. elegans. Genetic interactions confirm that UNC-129 does not require the only known type II TGF-beta receptor in C. elegans (DAF-4) for its guidance functions. Also, unc-130 is partially required for male tail morphogenesis and for embryogenesis.

Amino Acid Sequence↗
PubMed2000

Small-angle shubnikov-de haas measurements in a 2D electron system: the effect of a strong In-plane magnetic field

Measurements in magnetic fields applied at small angles relative to the electron plane in silicon MOSFETs indicate a factor of 2 increase of the frequency of Shubnikov-de Haas oscillations at H>H(sat). This signals the onset of full spin polarization above H(sat), the parallel field above which the resistivity saturates to a constant value. For H<H(sat), the phase of the second harmonic of the oscillations relative to the first is consistent with scattering events that depend on the overlap instead of the sum of the spin-up and spin-down densities of states. This unusual behavior may reflect the importance of many-body interactions.

Journal Article↗
PubMed2000

Congenital deafness and sinoatrial node dysfunction in mice lacking class D L-type Ca2+ channels.

Voltage-gated L-type Ca2+ channels (LTCCs) containing a pore-forming alpha1D subunit (D-LTCCs) are expressed in neurons and neuroendocrine cells. Their relative contribution to total L-type Ca2+ currents and their physiological role and significance as a drug target remain unknown. Therefore, we generated D-LTCC deficient mice (alpha1D-/-) that were viable with no major disturbances of glucose metabolism. alpha1D-/-mice were deaf due to the complete absence of L-type currents in cochlear inner hair cells and degeneration of outer and inner hair cells. In wild-type controls, D-LTCC-mediated currents showed low activation thresholds and slow inactivation kinetics. Electrocardiogram recordings revealed sinoatrial node dysfunction (bradycardia and arrhythmia) in alpha1D-/- mice. We conclude that alpha1D can form LTCCs with negative activation thresholds essential for normal auditory function and control of cardiac pacemaker activity.

Acoustic Stimulation↗
PubMed2000

[Relationship between vascular endothelial growth factor expression and microvessel density in hepatocellular carcinomas and their surrounding liver tissue].

The relationship between vascular endothelial growth factor (VEGF) expression and microvessel density was studied with immunohistochemical method in hepatocellular carcinoma (HCC) and pericarcinomatous liver tissue. The positive rate of VEGF in HCCs was significantly lower than in surrounding liver tissues (66.7% vs. 85.4%, P < 0.05). There was no significant difference between HCC and pericarcinomatous liver tissue on expressive intensity of VEGF. The positive signal of VEGF was mainly localized in cytoplasma of cancer cells, pericarcinomatous hepatocytes, and vascular endothelial cells. The microvessel density in HCC was higher than in pericarcinomatous liver tissue and closely correlated to differentiated degree of cancer cells (rs = 0.5870; rs = 0.8235). The poorer cancer cell differentiation, the higher microvessel density. The results suggest that VEGF may not be the sole factor that stimulates angiogenesis in HCC genesis and development. To detect microvessel density in judging prognosis and biological behavior of HCC is more important than that of VEGF.

Adult↗
PubMed2000

Phase transitions in the incoherent lattice fluctuations in YBa2Cu3O(7-delta)

The growing body of experimental evidence for the existence of complex textures of charges and spins in the high-temperature superconductors has drawn attention to the so-called 'stripe-phase' models as a possible basis for the mechanism of superconductivity in these materials. Such observations have until now been restricted to systems where the texture dynamics are slow or suppressed altogether, and do not include the important case of YBa2Cu3O(7-delta). It seems likely that the dynamic behaviour of stripes, which has been suggested to undergo several phase transitions as a function of temperature, should also be reflected in the lattice properties of the host materials, and this forms the motivation for our present experiments. Specifically, we use MeV helium ion channelling, an ultrafast real-space probe of atomic displacements (with sub-picometre resolution), to probe incoherent lattice fluctuations in YBa2Cu3O(7-delta) as a function of temperature and oxygen doping. We detect lattice fluctuations that are larger than the expected thermal vibration component, and which show anomalies characteristic of the phase transitions anticipated for a dynamic stripe phase. Comparison of our lattice results with single-particle-tunnelling and photoemission data highlights the importance of spin-charge separation phenomena in the copper oxide superconductors.

Journal Article↗
PubMed2000

Influenza A and B viruses expressing altered NS1 proteins: A vaccine approach.

We propose a rational approach to the generation of live viral vaccines: alteration of virally encoded type I IFN antagonists to attenuate virulence while retaining immunogenicity. We have explored this concept by using the influenza virus. Previously we have shown that the NS1 protein of influenza A virus possesses anti-IFN activity. We now present evidence that influenza A and B viruses encoding altered viral NS1 proteins are highly attenuated in the mouse host, yet provide protection from challenge with wild-type viruses.

Animals↗
PubMed2000

Parkinson's disease subtypes: clinical classification and ventricular cerebrospinal fluid analysis.

The current study presents preliminary data regarding the development and validation of a rating system designed to classify PD patients into clinical subgroups. Using portions of the Unified Parkinson's Disease Rating Scale, a ratio value was derived, yielding three patient subtypes: a tremor-dominant group (T), an akinetic-rigid group (AR), and a mixed group (MX). Validation of the schema was conducted by grouping PD surgical candidates into specific disease subtypes and evaluating differences in neurotransmitter profiles among disease subtypes and non-PD neurological controls. High pressure liquid chromatography analysis of ventricular cerebrospinal fluid indicated 5-hydroxyindoleacetic acid was significantly lower in the AR and MX groups compared to non-PD controls; whereas, glycine was significantly higher in the AR group compared to the T, MX, and control groups. The results suggest that an operational approach can be utilized to differentiate between PD subtypes with distinct neurochemical profiles.

Journal Article↗
PubMed2000

Spontaneous radiation and lamb shift in three-dimensional photonic crystals

Spontaneous emission in photonic crystals with anisotropic three-dimensional dispersion relation is studied. If the upper level is below a characteristic frequency omega(1), or above omega(2), or between omega(1) and omega(2), the radiation is a localized field with a frequency in the band gap, or a propagating field with a frquency in the band, or a diffusion field, respectively. An analytical expression for the Lamb shift is obtained. The Lamb shift for the current case is small compared to that in an ordinary vacuum or in one- or two-dimensional photonic crystals due to lower density of states.

Journal Article↗