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Biomedical subjects

Y Tao

Publications and source records attributed to Y Tao.

At least 55 records · Page 3Linked to original sources
PubMed2000

Blue-luminescent/electroluminescent Zn(II) compounds of 7-azaindole and N-(2-pyridyl)-7-azaindole: Zn(7-azaindole)2(CH3COO)2, Zn(NPA)(CH3COO)2, and Zn(NPA)((S)-(+)-CH3CH2CH(CH3)COO)2 (NPA = N-(2-pyridyl)-7-azaindole).

A new 7-azaindole zinc(II) compound, Zn(7-azaindole)2(CH3COO)2 (1), a new ligand N-(2-pyridyl)-7-azaindole (NPA), and two NPA zinc(II) complexes, Zn(NPA)(CH3COO)2 (2) and Zn(NPA)((S)-(+)-CH3CH2CH(CH3)COO)2 (3), have been synthesized and structurally characterized. Compound 1 has a tetrahedral geometry, whereas compounds 2 and 3 have irregular six-coordinate geometry. The NPA ligand in compounds 2 and 3 functions as a bidentate chelate to the zinc center. Compound 1 has a blue luminescence in the solution and the solid state. Compounds 2 and 3 emit a blue color in the solid state. In solution, compounds 2 and 3 are fluxional, as established by 1H NMR experiments. Compound 1 is thermally stable, whereas compounds 2 and 3 undergo decomposition when heated in the solid state. A blue electroluminescent device using compound 1 as the emitting layer has been fabricated. Crystal data: NPA, monoclinic, P2(1)/c, a = 13.993(5) A, b = 8.456(3) A, c = 16.886(5) A, beta = 104.666(12) degrees, V = 1932.9(11) A3; 1, triclinic, P1, a = 9.5114(18) A, b = 10.460(7) A, c = 11.002(3) A, alpha = 117.18(3) degrees, beta = 103.287(18) degrees, gamma = 90.94(2) degrees, V = 938.3(7) A3; 2, monoclinic, C2/c, a = 13.234(6) A, b = 9.373(3) A, c = 13.956(7) A, beta = 113.24(3) degrees, V = 1590.7(12) A3; 3, monoclinic, P2(1), a = 11.047(7) A, b = 15.343(9) A, c = 13.785(8) A, beta = 100.123(9) degrees, V = 2300(2) A3.

Journal Article↗
PubMed2000

Molecular cloning of a novel water channel from rice: its products expression in Xenopus oocytes and involvement in chilling tolerance.

Water channel proteins, aquaporins, play a fundamental role in transmembrane water movements in plants. We isolated rice cDNA, rwc1, by screening a rice (Oryza sativa cv. Josaeng Tongil) cDNA library using a conserved motif of aquaporins. Like other aquaporin genes, rwc1 encodes a 290-residue protein with six putative transmembrane domains. The derived amino acid sequence of RWC1 shows high homology with PIP1 (plasma membrane intrinsic protein 1) subfamily members, which suggest it is localized in the plasma membrane. Injection of its cRNA into Xenopus oocytes increased the osmotic water permeability of the oocytes 2-3 times. Northern analysis showed that rice aquaporin genes are expressed in rice seedling leaves and roots, but that it disappeared from the root 6 h after osmotic stress began and that the transcript level remained low for about 24 h, then recovered. The time course of rice aquaporin gene-expression under osmotic stress was correlated with time course of turgor transition in plant. On the other hand, the levels of rice aquaporin gene-transcripts in leaves under chilling and recovery temperature depend on the pretreatment of mannitol for short time. This variation of the transcripts shown that rice aquaporin genes may play an important role in response to water stress-induced chilling tolerance.

Journal Article↗
PubMed2000

[Effects of microwave radiation on lipid peroxidation and the content of neurotransmitters in mice].

Male LACA mice were exposed to 900 MHz microwaves at the power densities of 0,1,2 and 5 mW/cm2. The resulting specific absorption rates(SARs) were 0, 0.22, 0.44 and 1.10 W/kg respectively. Animals were exposed at the dosage of 1 hour a day for 35 days. The results showed that the activity of glutathione peroxidase (GSH-Px) increased and the concentration of malondialdehyde (MDA) decreased in blood, and the concentration of noradrenaline (NE) increased in brains in the microwave exposed groups at 1 mW/cm2 compared with the sham-exposed group. But no significant changes were found in the microwave exposed groups at 2 and 5 mW/cm2. No significant changes of the concentrations of 5-hydroxytryptamine(5-HT), 5-hydroxyindole acetic acid(5-HIAA) and dopamie(DA) in brains were found.

Animals↗
PubMed2000

Detection and its implication of heat stress protein 27 and P21 in nasopharyngeal carcinoma.

To study the expression of heat stress protein 27 (HSP27) and P21 in nasopharyngeal carcinoma (NPC) tissue, and to evaluate the significance of both HSP27 and P21 in the pathogenesis, development and prognosis of NPC. Indirect immunofluorescence method combined with SABC was applied. Our results showed that (1) the positive rates of HSP27 and P21 expressed in NPC tissue in 36 cases were 88.9% and 94.4%; (2) while in 10 hyperplastic nasopharyngitis tissues, the positive rate of HSP27 and P21 were both 5; (3) all the 5 normal tissues were negatively stained. It is obvious that a co-expressing tendency of HSP27 and P21 could be identified, and it was associated with the degree of malignancy and the clinical stage of NPC. It is concluded that the positive expression of HSP27 and P21 may have clinical significance in the evaluation of the occurring, development and prognosis of NPC, and in NPC treatment.

Adult↗
PubMed2000

Recent developments in cryo-electron microscopy reconstruction of single particles.

Cryo-electron microscopy and single-particle 3D image reconstruction techniques have been used to examine a broad spectrum of samples ranging from 500 kDa protein complexes to large subcellular organelles. The attainable resolution has improved rapidly over the past few years. Structures of both symmetric and asymmetric assemblies at approximately 7.5 A have been reported. Together with X-ray crystallography, three-dimensional cryo-electron microscopy reconstruction has provided important insights into the function of many biological systems in their native biochemical contexts.

Automation↗
PubMed2000

Mutational analysis of the Arabidopsis nucleotide binding site-leucine-rich repeat resistance gene RPS2.

Disease resistance proteins containing a nucleotide binding site (NBS) and a leucine-rich repeat (LRR) region compose the largest class of disease resistance proteins. These so-called NBS-LRR proteins confer resistance against a wide variety of phytopathogens. To help elucidate the mechanism by which NBS-LRR proteins recognize and transmit pathogen-derived signals, we analyzed mutant versions of the Arabidopsis NBS-LRR protein RPS2. The RPS2 gene confers resistance against Pseudomonas syringae strains carrying the avirulence gene avrRpt2. The activity of RPS2 derivatives in response to AvrRpt2 was measured by using a functional transient expression assay or by expressing the mutant proteins in transgenic plants. Directed mutagenesis revealed that the NBS and an N-terminal leucine zipper (LZ) motif were critical for RPS2 function. Mutations near the N terminus, including an LZ mutation, resulted in proteins that exhibited a dominant negative effect on wild-type RPS2. Scanning the RPS2 molecule with a small in-frame internal deletion demonstrated that RPS2 does not have a large dispensable region. Overexpression of RPS2 in the transient assay in the absence of avrRpt2 also led to an apparent resistant response, presumably a consequence of a low basal activity of RPS2. The NBS and LZ were essential for this overdose effect, whereas the entire LRR was dispensable. RPS2 interaction with a 75-kD protein (p75) required an N-terminal portion of RPS2 that is smaller than the region required for the overdose effect. These findings illuminate the pathogen recognition mechanisms common among NBS-LRR proteins.

Amino Acid Sequence↗
PubMed2000

Purification, crystallization and initial X-ray analysis of the head-tail connector of bacteriophage phi29.

The head-tail connector of bacteriophage phi29, an oligomer of gene product 10 (gp10), was crystallized into various forms. The most useful of these were an orthorhombic P22(1)2(1) form (unit-cell parameters a = 143.0, b = 157.0, c = 245.2 A), a monoclinic C2 form (a = 160.7, b = 143.6, c = 221.0 A, beta = 97.8 degrees ) and another monoclinic C2 form (a = 177.0, b = 169.1, c = 185.2 A, beta = 114.1 degrees ). Frozen crystals diffracted to about 3.2 A resolution. There is one connector per crystallographic asymmetric unit in each case. Rotation functions show the connector to be a dodecamer. Translation functions readily determined the position of the 12-fold axis in each unit cell. The structure is being determined by 12-fold electron-density averaging within each crystal and by averaging between the various crystal forms.

Bacillus Phages↗
PubMed2000

Detection of point mutations in promoter and coding sequence of p21 gene in a variety of human malignancies.

OBJECTIVE: p21 is a general inhibitor of cyclin-dependent kinases which leads cells through restriction point of cell cycle. Since p21 has been identified to be a mediator of p53 tumor suppressor activity and directly up-regulated by p53, this study was designed to investigate whether mutations in promoter or coding sequence of p21 were associated with development or progress of tumor. METHODS: A 2.4kb DNA fragment, containing essential promoter, was amplified and sequenced. Furthermore, 346 DNA samples from 9 different types of primary tumors were examined for point mutations in promoter and coding sequence of p21 gene by using SSCP analysis and direct sequencing. RESULTS: Heterozygous or homozygous G to A transition at 5bp upstream and C to A transversion at 160bp downstream of p53 binding site were found. A 44bp heterozygous deletion was detected in a bladder cancer, which started at codon 34 and resulted in frameshift and a premature stop codon downstream. The most abundant variants in coding sequence of p21 gene were a C to A transversion at codon 31 which resulted in Ser to Arg and had been identified being polymorphism. In addition, four rare variants in coding sequence were also found. CONCLUSION: The evidence from this study indicates that mutation in either promoter or coding sequence of p21 gene is rare in a variety of human malignancies.

Cyclin-Dependent Kinase Inhibitor p21↗
PubMed2000

[Effects of -30 degrees head down tilt on lung function].

OBJECTIVE: To investigate the effects of short-term simulated weightlessness on lung function in healthy males. METHOD: -30 degrees head down tilt for 45 min was used to simulate short-period weightlessness. Lung function of 12 healthy males, aged 18-21, were studied with plethysmography during seating, supine and head down tilt positions. At the same time, blood flow in pulmonary artery and function of right ventricle were measured with Doppler Echo-Cardiography. Comparative analysis was done. RESULT: As body position changed from seating or supine into head down tilt, FVC, FEV1, FEV1%, MVV, VA and IVC decreased. The change of MVV was the most prominent (P < 0.000). As the position changed, pulmonary diffusion increased dramatically (DL(CO) P<0.001, K(CO) P<0.000). CONCLUSION: HDT may lead to a decrease of pulmonary ventilation and lung capacity. The increased pulmonary diffusion might be related to uniform distribution of pulmonary blood flow and increased effective pulmonary vascular bed.

Adolescent↗
PubMed2000

[Distribution and transferring of carbon in kast soil system of peak forest depression in humid subtropical region].

Taking Guilin Yaji Karst Experiment Site as an exemple and with the methods of field monitoring and laboratory analysis, this paper studied the distribution and transferring of carbon in the karst soil system of peak forest depression in the humid subtropical region of China. The carbon pools in biomass, litters and soil organic matter(SOM) and their mobility as expressed by oxidizability and decomposition rate of SOM, the concentration of soil CO2 and the emission rate of CO2 from soil were investigated. The mobile carbon pool in the system supplied a rich source of CO2, which drived the karst process. When active karst process happened in Spring and Summer, over 60% of carbon in the output water was derived from soil CO2, as traced by delta 13 C distribution in the system. Therefore, owing to the carbon transfer in the pathway of air-plant-soil-water, karst process took place rather under soil-rock-water interface than under air-rock-water interface. Thus, the epigenetic karst process was driven and accelerated by soil as an interface of carbon environmental geochemistry.

Carbon↗
PubMed2000

[The preliminary study on the gene mutations of sixty patients with G6PD deficiency in Yunnan province].

OBJECTIVE: To analyze the types and distribution of glucose-6-phosphate dehydrogenase (G6PD) gene mutations in Yunnan province. METHODS: By using the natural primers or mis-matched primers mediated polymerase chain reaction (PCR) followed by endonuclease digestion methods, six types of G6PD gene mutations, G1388A, G1376T, C1024T, G392T, C592T and A95G were in sixty patients with G6PD deficiency. RESULT: Six types of mutation were revealed: 28.3% (17 of 60) were G1388A, 11.7% (7 of 60) G1376T, 6.7% (4 of 60) C1024T, 1.7% (1 of 60) G392T, 1.7% (1 of 60) C592T, 1.7% (1 of 60) A95G and 48.3% (29 of 60) unidentified. C592T mutation is the first report in Yunnan people. CONCLUSIONS: The G6PD gene in Yunnan people is heterogeneous. Research of G6PD gene mutation types may provide some useful data for clinical diagnosis and prevention of G6PD deficiency, and for human genetic study.

Amino Acid Substitution↗
PubMed2000

[An experimental study combined on traditional Chinese medicine with immunosuppressant for treatment and prevention of tubular interstitial nephritis].

The objective of this study was to determine the effect of Chinese herbs and immune inhibitors on diffuse proliferative glomerulonephritis. The tubular-interstitial infiltration of cell, TGF-beta expression and interstitial fibrosis were investigated, and the relationship between clinical data and pathological changes was analysed. The results showed the infiltration of cells was inhibited in the "Chinese herbs combined with prednisone" group, the infiltration of cells, TGF-beta expression and interstitial fibrosis were all inhibited in the cyclophosphamide and prednisone" group. But in the prednisone group, interstitial fibrosis was not inhibited. These data suggest that the combined use of Chinese herbs, immunosuppressant and prednisone can inhibit the interstitial cell infiltration and prevent the interstitial fibrosis in diffuse proliferative glomerulonephritis.

Animals↗
PubMed2000

[Effects of electromagnetic radiation from cellular telephone handsets on symptoms of neurasthenia].

In order to study the effects of electromagnetic radiation from cellular telephone handsets on symptoms of neurasthenia, 115 and 101 persons with or without handsets were selected. The subjects were investigated by questionnaire on their general health, lifestyle, habit, mental stress, the frequency of using the handsets, living and working environment, the cases of suffered from diseases and symptoms of neurasthenia. The data were analyzed by Chi-square test and Logistic regression statistics. The results showed that the time of using handset was positively associated with depression (P < 0.05), nausea (P < 0.01) and loss of appetite(P < 0.05). The results showed that long time use of cellular telephone handset could induce the symptoms of neurasthenia.

Female↗
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↗
PubMed1999

Lattice-fluid model for gas-liquid chromatography.

Lattice-fluid models describe molecular ensembles in terms of the number of lattice sites occupied by molecular species (r-mers) and the interactions between neighboring molecules. The lattice-fluid model proposed by Sanchez and Lacombe (Macromolecules, 1978;11:1145-1156) was used to model specific retention volume data for a series of n-alkane solutes with n-alkane, polystyrene, and poly(dimethylsiloxane) stationary liquid phases. Theoretical equations were derived for the specific retention volume and also for the temperature dependence and limiting (high temperature) values for the specific retention volume. The model was used to predict retention volumes within 10% for the n-alkanes phases; 22% for polystyrene; and from 20 to 70% for PDMS using no adjustable parameters. The temperature derivative (enthalpy) could be calculated within 5% for all of the solutes in nine stationary liquid phases. The limiting value for the specific retention volume at high temperature (entropy controlled state) could be calculated within 10% for all of the systems. The limiting data also provided a new chromatographic method to measure the size parameter, r, for any chromatographic solute using characteristic and size parameters for the stationary phase only. The calculated size parameters of the solutes were consistent, i.e. independent of the stationary phase and agreed within experimental error with the size parameters previously reported from saturated vapor pressure, latent heat of vaporization or density data.

Alkanes↗
PubMed1999

[Effects of strontium in drinking water on the growth of school-age children].

An epidemiological study on the effect of strontium in drinking water on body shape development, bone age, prevalence of caries and dental fluorosis was carried out. The results show: there is a certain promotion on the development of bone age of school-age children, especially of girls, and there is no obvious impact on body shape developing when the concentration of strontium in drinking water is only 10 mg/L. The correlation between strontium in drinking water and the prevalence of caries in children could not get a conclusive evidence in this paper. A further epidemiological investigation is necessary if the role of strontium against caries should be proved.

Adolescent↗