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Biomedical subjects

Ying Zhang

Publications and source records attributed to Ying Zhang.

At least 397 records · Page 22Linked to original sources
PubMed2004

[Synthesis and antitumor activities of 10-hydroxy camptothecin derivatives].

AIM: To find new anticancer drug based on the structure of 10-hydroxy camptothecin. METHODS: Seven camptothecin derivatives (3 -9) were synthesized and the antitumor activities of these derivatives were evaluated. RESULTS: Structures of seven new compounds were determined by 1HNMR, IR, MS. Seven compounds showed inhibitory effects on Hela, BEL-7402, 7901 cell lines in vitro. Especially, compound 4 showed high bioactivities to all of the tumor cells in vitro, its anticancer activity against human cervical carcinoma Hela was much higher than that of 10-hydroxy camptothecin. CONCLUSION: Some compounds are worth further studying.

Antineoplastic Agents↗
PubMed2004

[Construction of recombinant vector expressing ALAS2 gene in X-linked sideroblastic anemia].

X-linked sideroblastic anemia (XLSA) is caused by mutations of erythroid-specific 5-aminolevulinate synthetase (ALAS2) gene. In this study a eukaryotic expression vector of ALAS2 was constructed and transfected into eukaryotic cells to observe the expression of ALAS2 gene. The full length cDNA of ALAS2 gene was inserted into plasmid pDs-red2-N1, named pDs-red2-N1/ALAS2. Then, the vector was transfected into K562 cells via electroporation. At 48 hours after transfection, total RNA from K562 cells was extracted, expressions of ALAS2 gene and protein with red fluorescence in the K562 cells were detected by RT-PCR and flow cytometry, respectively. The vector was also transfected into COS 7 cells via liposome. Both mRNA and protein expression in COS7 cells were detected by RT-PCR and fluorescence microscopy. The result showed that after the pDs-red2-N1/ALAS2 eukaryotic expression vector was digested by KpnI and BamHI, two fragments of 4 700 bp and 1 764 bp were displayed by electrophoresis on agarose gel. Sequence method confirmed that the sequence was correct. RT-PCR amplified the total RNA extracted from the transfected K562 and COS7 cells, and could find mRNA of ALAS2 gene that can't be found in K562 and COS7 cells usually. The expressions of both fluorescein and ALAS2 were significantly increased. The percentage of positive cells reached about 19.2% and 10.7%, respectively. ALAS2 expression lasted for 10 days in COS7 cells and the peak was at the third day. It is concluded that the eukaryotic expression vector of ALAS2 gene is successfully constructed; K562 and COS7 cells transfected with the vector via electroporation and liposome can express ALAS2 protein. So, the vector has the potential in gene replacement and can be used for patients with XLSA in future.

5-Aminolevulinate Synthetase↗
PubMed2004

AT1 receptor in rostral ventrolateral medulla mediating blunted baroreceptor reflex in spontaneously hypertensive rats.

AIM: To determine the role of AT1 receptor in the rostral ventrolateral medulla (RVLM) in mediating the blunted baroreceptor reflex in spontaneously hypertensive rats (SHR). METHODS: Intravenous injections of graded doses of phenylephrine (1, 5, 10, 20, and 40 microg/kg) increased the blood pressure to elicit the baroreceptor reflex in both SHR and normotensive Wistar rats anesthetized with urethane. The baroreceptor reflex sensitivity (BRS) was determined before and after microinjection of Ang II, losartan, or AT1 receptor antisense oligodeoxynucleotides into the RVLM. AT1 receptor protein level in the RVLM was measured by Western blotting. RESULTS: The BRS was significantly decreased in SHR compared with normal rats. Bilateral microinjection of AT1 receptor antagonist losartan (250 nmol/h) into the RVLM partly reversed the blunted BRS in SHR, but had no significant effect on the BRS in normal rats. Ang II (1.5 nmol/h) significantly inhibited the BRS in normal rats, which was completely abolished by pretreatment with losartan. However, no significant change in the BRS was observed after microinjection of Ang II into the RVLM in SHR. Bilateral microinjection of AT1 receptor antisense oligodeoxynucleotides (ASODN) into the RVLM partially recovered the blunted BRS in SHR after 3 h, but no significant change in the BRS was observed in normal rats. The AT1 receptor protein level significantly decreased after administration of ASODN. CONCLUSION: Blockage of AT1 receptor or inhibition of AT1 receptor protein synthesis in the RVLM enhanced the BRS in SHR, suggesting that the enhanced activities of AT1 receptor in the RVLM contribute to the blunted BRS in SHR.

Angiotensin II↗
PubMed2004

Factors associated with the extent of care-seeking delay for patients with acute myocardial infarction in Beijing.

BACKGROUND: Prehospital delay remains one of the main causes of reduced benefit of reperfusion therapy for patients with acute myocardial infarction (AMI). The largest proportion of prehospital delay involves the interval between the onset of symptoms and the decision to seek medical treatment. The purpose of this study was to examine the factors associated with the extent of care-seeking delay in Beijing for patients with AMI. METHODS: A structured interview was conducted in 102 patients with AMI in eight hospitals in Beijing. RESULTS: The mean decision time in patients with AMI was (204 +/- 43) minutes, and prehospital delay time was (311 +/- 54) minutes. Only 34% of patients sought medical care within one hour and a further 36% of patients presented to one of the eight hospitals within two hours after onset. Educational level, atypical presentation of AMI, and family members at the site where AMI occurred were associated with longer delay time in seeking medical assistance (P < 0.05, respectively), whereas the intensity of chest pain was inversely related to patients' delay time (P < 0.01). Patients who perceived their family relationship as good, attributed their symptoms to AMI origin, knew the time-dependent nature of reperfusion therapy, or used emergency medical service tended to seek medical care in a more rapid manner (P < 0.05, respectively). CONCLUSIONS: Patients with AMI in Beijing delay seeking medical care to a great extent. Health education to increase the level of awareness of the target population at increased risk of AMI, including patients and their family members, is probably beneficial to reduce patients' care-seeking delay.

Cognition↗
PubMed2004

[A new technique of extracting effective components from Chinese herb and natural plant--microwave assisted extraction, MAE].

The extraction and separation of effective components from Chinese herb and natural plant is one of the most important processes of natural medicine production. Recently, more and more advanced techniques have been used in the field of modern Chinese medicines, for example, microwave-assisted extraction (MAE). Developed on the base of traditional extracting technology using by organic solvents, MAE is of higher extraction rate and efficiency and better extract quality, as well as few investment, simple equipment, wide adaptability, high selectivity, good fidelity and no pollution. This paper mainly reviews the action principle and characteristic of MAE and its application in the extraction of natural products such as flavonoids, glycosides, polysaccharides, terpenoids and essence. Otherwise, the developing foreground of MAE is also prospected here.

Drugs, Chinese Herbal↗
PubMed2004

[Epitope mapping of myeloperoxidase antibodies in propylthiouracil-induced vasculitis and microscopic polyangiitis].

OBJECTIVE: To compare the epitopes of antibodies for myeloperoxidase (MPO) in the serum from patients with propylthiouracil (PTU) induced vasculitis and microscopic polyangiitis (MPA). METHODS: Serum samples from patients with PTU-induced vasculitis (n = 10) and MPA (n = 10) were collected and used to inhibit monoclonal antibodies against human MPO 3D8 and 6B9 and then affinity was purified, horseradish peroxidase conjugated and human MPO antibodies determined (Pab1-HRP, Pab2-HRP) in a competitive inhibition ELISA system using soluble human MPO as solid phase ligands. The Pab1-HRP and Pab2-HRP were affinity purified from plasma exchanges of a patient with PTU-induced vasculitis and a patient with MPA. The inhibition rates were evaluated and compared between PTU group and primary MPA group. RESULTS: In PTU group, all the 10 serum samples could inhibit 3D8; the average inhibition rate was 44.7%, 9/10 of the serum samples could inhibit 6B9; the average inhibition rate was 35.6%; In MPA group, all 10 serum samples could inhibit 3D8 and 6B9; the average inhibition rates were 68.4% and 62.2%. Serum in both groups could inhibit Pab1-HRP and the inhibition rates were both more than 80%; the average inhibition rate for Pab2-HRP in MPA group was significantly higher than that in PTU group (76.3% vs 58.9%, P < 0.01). CONCLUSIONS: MPO antibodies from patients with PTU-induced vasculitis and patients with primary MPA could recognize more than one epitopes on native MPO molecule. Although the epitopes were overlapping between the two groups, the epitopes of MPO antibodies from patients with PTU-induced vasculitis might be more restricted.

Adolescent↗
PubMed2003

High sexual signalling rates of young individuals predict extended life span in male Mediterranean fruit flies.

In a laboratory study, we monitored the lifetime sexual signalling (advertisement) of wild male Mediterranean fruit flies, and we tested the hypothesis that high lifetime intensity of sexual signalling indicates high survival probabilities. Almost all males exhibited signalling and individual signalling rates were highly variable from the beginning of the adults' maturity and throughout their life span (average life span 62.3 days). Sexual signalling rates after day 10 (peak maturity) were consistently high until about 1 week before death. There was a positive relationship between daily signalling rates and life span, and an increase in signalling level by one unit over all times was associated with an approximately 50% decrease in mortality rate. Signalling rates early in adult life (day 6-20) were higher in the longest-lived than in the shortest-lived flies. These results support the hypothesis that intense sexual signalling indicates longer life span. We discuss the importance of age-specific behavioural studies for understanding the evolution of male life histories.

Animal Communication↗
PubMed2003

Regulation on the expression and N-glycosylation of integrins by N-acetylglucosaminyltransferase V.

The expressions of integrin alpha5, beta1, and alpha6 were studied in H7721 cells by means of flow cytometric and RT-PCR method after transfected with sense and antisense cDNA of N-acetylglucosaminyltransferase V (GnT-V). The transfected cells were characterized by Northern blot. It was found that the order of expression from high to low was beta1>alpha5>alpha6. Transfection of sense GnT-V up-regulated alpha5 and alpha6, but not beta1 subunit, while antisense GnT-V down-regulated alpha5 and beta1, but not alpha6. The alterations of surface integrin subunits were quite compatible with the changes of their mRNAs. Using enzyme-labeled lectin analysis, it was shown that alpha5 subunit contained only C(2)C(2) biantennary N-glycan, which was not regulated by sense and antisense GnT-V. In contrast, beta1 subunit contained both biantennary and tri-/tetra-antennary N-glycans with GlcNAcbeta1,6Manalpha1,6-branch, and the latter was up- and down-regulated by the sense and antisense GnT-V, respectively. Therefore, the amount of biantennary N-glycans on beta1 subunit, but not the integrin protein, was correlated to the cell adhesion to fibronectin and laminin, which was reduced and elevated in the sense and antisense GnT-V-transfected cells, respectively, as we previously reported.

Cell Line↗
PubMed2003

Mode of action of pyrazinamide: disruption of Mycobacterium tuberculosis membrane transport and energetics by pyrazinoic acid.

Pyrazinamide is an important sterilizing drug that shortens tuberculosis (TB) therapy. However, the mechanism of action of pyrazinamide is poorly understood because of its unusual properties. Here we show that pyrazinoic acid, the active moiety of pyrazinamide, disrupted membrane energetics and inhibited membrane transport function in Mycobacterium tuberculosis. The preferential activity of pyrazinamide against old non-replicating bacilli correlated with their low membrane potential and the disruption of membrane potential by pyrazinoic acid and acid pH. Inhibitors of membrane energetics increased the antituberculous activity of pyrazinamide. These findings shed new light on the mode of action of pyrazinamide and may help in the design of new drugs that shorten therapy.

Antitubercular Agents↗
PubMed2003

[The variation of T-cell clonal repertoire in patients with systemic lupus erythematosus (SLE) following autologous peripheral blood hematopoietic stem cell transplantation].

OBJECTIVE: Analyze the variation of T cell receptor(beta) (TCRbeta) CDR3 gene expressing repertoire in systemic lupus erythematosus (SLE) patients before and after autologous peripheral blood hematopoietic stem cell transplantation (APBSCT), to search the pathogenesis of SLE and characteristics of T cell reconstitute immune after APBSCT. METHODS: Reverse transcriptase - polymerase chain reaction (RT-PCR) amplified 25 subfamily genes of TCRbeta prom peripheral blood lymphocytes (PBLs) of SLE patient with APBSCT and run denaturation polyacrylamide sequencing gel electrophoresis, set up a map of TCRbetaCDR3 gene expressing repertoire. The bands of TCRbeta gene repertoire in the electrophoresis gel can be used to analyze the variety of T cell clones which expanded and disappeared in cases of SLE. Cut the bands and sequencing. Compare sequences of TCRbetagenes in normal and abnormal T cell clones to understand the relationship between TCRbeta gene and autoimmune diseases. RESULTS: In the normal control group, TCRbeta gene repertoires show more than 10 bands in each of 25 TCRbetaV families, characterized as Gaussian distribution. TCRbeta gene repertoire in the 8 patients with SLE were abnormally. Four patients expressed TCRbetaV13.1 gene preferentially. Three patients had TCRbetaV8, TCRbetaV9 and TCRbetaV18 genes over expressed. These over expressive genes represented the oligoclonal expansion of T cell populations. After APBSCT the TCRbeta gene repertoires regained CDR3 polymorphism in 5 patients, some of them recovered to normal completely. The sequencing analyse show dense and strong band in map of TCRbeta gene repertoires were T cell monoclonal or oligoclonal expansion frequently. In a case of SLE an amino acid sequence of TCRbetaV8 CDR3 was same to a sequence of disease correlative T cell clone with ankylosing spondylitis that had been reported in a literature before. CONCLUSION: SLE patients have oligoclonal expansion of T cell that related with the pathogenesis of autoimmune disease. After APBSCT, T cell clones recover to normal distribution. T cell clones that related with disease have been suppressed during immunological reconstitution. It may be a main reason the SLE get remission after transplantation.

Adolescent↗
PubMed2003

Overexpression of a hyperpolarization-activated cation current (Ih) channel gene modifies the firing activity of identified motor neurons in a small neural network.

The hyperpolarization-activated cation current (Ih) is widely distributed in excitable cells. Ih plays important roles in regulation of cellular excitability, rhythmic activity, and synaptic function. We previously showed that, in pyloric dilator (PD) neurons of the stomatogastric ganglion (STG) of spiny lobsters, Ih can be endogenously upregulated to compensate for artificial overexpression of the Shal transient potassium channel; this maintains normal firing properties of the neuron despite large increases in potassium current. To further explore the function of Ih in the pyloric network, we injected cRNA of PAIH, a lobster gene that encodes Ih, into rhythmically active PD neurons. Overexpression of PAIH produced a fourfold increase in Ih, although with somewhat different biophysical properties than the endogenous current. Compared with the endogenous Ih, the voltage for half-maximal activation of the PAIH-evoked current was depolarized by 10 mV, and its activation kinetics were significantly faster. This increase in Ih did not affect the expression of IA or other outward currents. Instead, it significantly altered the firing properties of the PD neurons. Increased Ih depolarized the minimum membrane potential of the cell, reduced the oscillation amplitude, decreased the time to the first spike, and increased the duty cycle and number of action potentials per burst. We used both dynamic-clamp experiments, injecting the modeled PAIH currents into PD cells in a functioning STG, and a theoretical model of a two-cell network to demonstrate that the increased Ih was sufficient to cause the observed changes in the PD activity.

Action Potentials↗
PubMed2003

Visualization of membrane protein domains by cryo-electron microscopy of dengue virus.

Improved technology for reconstructing cryo-electron microscopy (cryo-EM) images has now made it possible to determine secondary structural features of membrane proteins in enveloped viruses. The structure of mature dengue virus particles was determined to a resolution of 9.5 A by cryo-EM and image reconstruction techniques, establishing the secondary structural disposition of the 180 envelope (E) and 180 membrane (M) proteins in the lipid envelope. The alpha-helical 'stem' regions of the E molecules, as well as part of the N-terminal section of the M proteins, are buried in the outer leaflet of the viral membrane. The 'anchor' regions of E and the M proteins each form antiparallel E-E and M-M transmembrane alpha-helices, leaving their C termini on the exterior of the viral membrane, consistent with the predicted topology of the unprocessed polyprotein. This is one of only a few determinations of the disposition of transmembrane proteins in situ and shows that the nucleocapsid core and envelope proteins do not have a direct interaction in the mature virus.

Cryoelectron Microscopy↗
PubMed2003

Arbuscular mycorrhizal fungi associated with common pteridophytes in Dujiangyan, southwest China.

The colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with common pteridophytes were investigated in Dujiangyan, southwest China. Of the 34 species of ferns from 16 families collected, 31 were colonized by AM fungi. The mean percentage root length colonized was 15%, ranging from 0 to 47%. Nineteen species formed Paris-type and 10 intermediate-type AM. In two ferns, only rare intercellular non-septate hyphae or vesicles were observed in the roots and AM type could not be determined. Of the 40 AM fungal taxa belonging to five genera isolated from rooting-zone soils, 32 belonged to Glomus, five to Acaulospora, one to Archaeospora, one to Entrophospora, and one to Gigaspora. Acaulospora and Glomus were the dominant genera and Glomus versiforme was the most common species. The average AM spore density was 213 per 100 g air-dried soil and the average species richness was 3.7 AM species per soil sample. There was no correlation between spore density and percentage root length colonized by AM fungi.

China↗
PubMed2003

Spreading and synchronization of intrinsic signals in visual cortex of macaque monkey evoked by a localized visual stimulus.

Spatio-temporal maps of the occipital cortex of macaque monkeys were analyzed using optical imaging of intrinsic signals. The images obtained during localized visual stimulation (IS) were compared with the images obtained on presentation of a blank screen (IB). We first investigated spontaneous variations of the intrinsic signals by analyzing the 100 IBs for each of the three cortical areas. Slow periodical activation was observed in alternation over the cortical areas. Cross-correlation analysis indicated that synchronization of spontaneous activation only took place within each cortical area, but not between them. When a small, drifting grating (2 degrees x 2 degrees ) was presented on the fovea, a dark spot appeared in the optical image at the cortical representation of this retinal location. It spread bilaterally along the border between V1 and V2, continuing as a number of parallel dark bands covering a large area of the lateral surface of V1. Cross-correlation analysis showed that during visual stimulation the intrinsic signals over all of the three cortical areas were synchronized, with in-phase activation of V1 and V2 and anti-phase activation of V4 and V1/V2. The significance of these extensive synergistic and antagonistic interactions between different cortical areas is discussed.

Animals↗
PubMed2003

Nonequilibrium, multiple-timescale simulations of ligand-receptor interactions in structured protein systems.

Predicting the long-time, nonequilibrium dynamics of receptor-ligand interactions for structured proteins in a host fluid is a formidable task, but of great importance to predicting and analyzing cell-signaling processes and small molecule drug efficacies. Such processes take place on timescales on the order of milliseconds to seconds, so "brute-force" real-time, molecular or atomic simulations to determine absolute ligand-binding rates to receptor targets and over a statistical ensemble of systems are not currently feasible. In the current study, we implement on real protein systems a previously developed 3-5 hybrid molecular dynamics/Brownian dynamics algorithm, which takes advantage of the underlying, disparate timescales involved and overcomes the limitations of brute-force approaches. The algorithm is based on a multiple timescale analysis of the total system Hamiltonian, including all atomic and molecular structure information for the system: water, ligand, and receptor. In general, the method can account for the complex hydrodynamic, translational-orientational diffusion aspects of ligand-docking dynamics as well as predict the actual or absolute rates of ligand binding. To test some of the underlying features of the method, simulations were conducted here for an artificially constructed spherical protein "made" from the real protein insulin. Excellent comparisons of simulation calculations of the so-called grand particle friction tensor to analytical values were obtained for this system when protein charge effects were neglected. When protein charges were included, we found anomalous results caused by the alteration of the spatial, microscopic structure of water proximal to the protein surface. Protein charge effects were found to be highly significant and consistent with the recent hypothesis of Hoppert and Mayer (Am Sci 1999;87:518-525) for charged macromolecules in water, which involves the formation of a "water dense region" proximal to the charged protein surface followed by a "dilute water region." We further studied the algorithm on a D-peptide/HIV capside protein system and demonstrated the algorithms utility to study the nonequilibrium docking dynamics in this contemporary problem. In general, protein charge effects, which alter water structural properties in an anomalous fashion proximal to the protein surface, were found to be much more important than the so-called hydrodynamic interaction effects between ligand and receptor. The diminished role of hydrodynamic interactions in protein systems allows for a much simpler overall dynamic algorithm for the nonequilibrium protein-docking process. Further studies are now underway to critically examine this simpler overall algorithm in analyzing the nonequilibrium protein-docking problem.

Algorithms↗
PubMed2003

Flexible DNA bending in HU-DNA cocrystal structures.

HU and IHF are members of a family of prokaryotic proteins that interact with the DNA minor groove in a sequence-specific (IHF) or non-specific (HU) manner to induce and/or stabilize DNA bending. HU plays architectural roles in replication initiation, transcription regulation and site-specific recombination, and is associated with bacterial nucleoids. Cocrystal structures of Anabaena HU bound to DNA (1P71, 1P78, 1P51) reveal that while underlying proline intercalation and asymmetric charge neutralization mechanisms of DNA bending are similar for IHF and HU, HU stabilizes different DNA bend angles ( approximately 105-140 degrees ). The two bend angles within a single HU complex are not coplanar, and the resulting dihedral angle is consistent with negative supercoiling. Comparison of HU-DNA and IHF-DNA structures suggests that sharper bending is correlated with longer DNA binding sites and smaller dihedral angles. An HU-induced bend may be better modeled as a hinge, not a rigid bend. The ability to induce or stabilize varying bend angles is consistent with HU's role as an architectural cofactor in many different systems that may require differing geometries.

Anabaena↗