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Biomedical subjects

Z Qi

Publications and source records attributed to Z Qi.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Water quality of closed polyculture of penaeid shrimp with tilapia and constricted tagelus].

A variety of water quality parameters were monitored in enclosures for the polyculture of penaeid shrimp with tilapia and constricted tagelus. The result showed that the environment of the polyculture systems was better than that of monoculture one. The fluctuation of DO in the water of polyculture enclosures was less violent, and their lowest values were obviously higher than those in monoculture ones. The value of COD and the number of bacteria in the water of polyculture enclosures were significantly lower than those in monoculture ones(t-test, alpha < 0.05), showing that the amount of organic matter in the water of polyculture systems was less than that in monoculture one. The biomass of plankton and the concentration of chlorophyll-a in the polyculture enclosures were also lower, showing that the suppression of the filtering animals to the plankton was obvious. The accumulation of N and P in the sediment of polyculture enclosures was 39.76% and 51.26%, lower than those of monoculture ones, respectively; and the number of bacteria in the sediment was 7.63% lower. Therefore, it is obvious that closed culture system can greatly decrease the effluent to the coastal waters caused by the pond culture industry, and decrease the pollution to the coastal waters.

Animals↗
PubMed2001

High level expression of human factor VIII in mammalian cells after retroviral-mediated gene transfer.

OBJECTIVE: To develop a retroviral-mediated high efficient expression system of human coagulation factor VIII. METHODS: The LNC-FVIIIBD retroviral vector was generated by cloning a human B-domain-deleted (760aa-1639aa) Factor VIII (FVIII) cDNA (FVIII cDNA BD) into the retroviral vector pLNCX. Several mammalian cell lines, including NIH3T3, CHO, Cos-7 and human hepatic cell line, L-02, were transduced with viral supernatant from the highest virus-producing PA317 clone. Antigen and coagulant activity of human FVIII in cell culture medium were measured by ELISA and a one-stage method, respectively. RT-PCR was performed for the detection of FVIIIBD mRNA. RESULTS: Human FVIII was expressed in all four target cells, with the highest FVIII expression observed in NIH3T3. The coagulant activity of secreted FVIII was up to 1.6 U/10(6) cells.24 hrs-1, and the FVIII antigen was 500 ng/10(6) cells.24 hrs-1. FVIII coagulant activity and antigen expressed by transduced CHO cells were 0.12 U/10(6) cells.24 hrs-1 and 62.4 ng/10(6) cells.24 hrs-1, respectively. Human FVIII expression was relatively low in Cos-7 and L-02 cells. RT-PCR results demonstrated transcription of FVIII cDNA BD in the target cells. CONCLUSIONS: The constructed retroviral vector was able to direct high level expression of human FVIII in various mammalian cell lines. It has potential utility in the future gene therapy for Hemophilia A.

Animals↗
PubMed2001

[A century of developmental history of laparoscopic surgery].

Till the year 2001, the development of laparoscopic surgery will have gone through a total of one hundred years. Laparoscopic surgery has made a great progress during the last more than a decade. In retrospect its history, the development of laparoscopic surgery underwent three main eras, viz. diagnostic laparoscopy, operative laparoscopy and the modern laparoscopy era. Although the laparoscopic technology started rather late in China, it develops very quickly. Along with the development of high -- tech, laparoscopic surgery will have a promising future.

History, 20th Century↗
PubMed2001

[Cloning and phylogenetic analysis of hepatitis-associated TT virus subgenome].

Polymerase chain reaction (PCR) was utilized for the DNA amplification from transfusion transmitted virus (TTV) positive serum samples. Five TTV DNA fragments, overlapped about 90% of the genome, were amplified by long template PCR for the generation of TTV subgenome. Recombinant plasmids were obtained by directly inserting PCR products into pT-Adv vector, and DNA sequence analyses showed they were TTV DNA fragments. By using specific restriction enzymes, five TTV DNA fragments were ligated into a TTV DNA subgenome clone and named as TTV021. TTV021 has been deposited in GenBank database with the accession number AF254410. The results of computer analyses showed that TTV021, 3472 nt long, contains two open reading frames (ORF1, 785 aa; ORF2, 146 aa). Identity alignments between TTV021 and other TTV isolates indicated several high conserved regions existed. Phylogenetic analysis of 356 nt from TTV021 suggested that the isolate has close evolutionary relationship with CHN1 (type 1a), but has far relation with other TTV isolates.

Circoviridae↗
PubMed2000

Identification of a common protein association region in the neuronal Cdk5 activator.

Cyclin-dependent protein kinase 5 (Cdk5) depends on the association with neuronal Cdk5 activator (Nck5a) for kinase activity. A variety of cellular proteins have been shown to undergo high affinity association with Nck5a, including three novel proteins, C42, C48, and C53 found by a yeast two-hybrid screen (Ching, Y. P., Qi, Z., and Wang, J. H. (2000) Gene 242, 285-294). The three proteins show competitive binding to Nck5a suggesting that they bind at a common site. The binding site has been mapped to a region of 26 amino acid residues (residues 145 to 170) at the N-terminal boundary of the kinase activation domain of Nck5a. This region of Nck5a contains an amphipathic alpha-helix whose hydrophobic face is involved in Cdk5 activation (Chin, K. T., Ohki, S, Tang, D., Cheng, H. C., Wang, J. H. , and Zhang, M. (1999) J. Biol. Chem. 274, 7120-7127). Several lines of evidence suggest that Nck5a interacts with the binding proteins at the hydrophilic face of the amphipathic alpha-helix. First, the Nck5a-(145-170) peptide can bind Cdk5 and Nck5a-binding proteins simultaneously. Second, the association of Nck5a-(145-170) to C48 can be markedly reduced by high ionic strength whereas the interaction between Nck5a and Cdk5 is not affected. Third, substitution of Glu(157) by glutamine in Nck5a-(145-170) abolishes the peptide's ability to bind to the three Nck5a-binding proteins without diminishing its Cdk5 binding activity.

Amino Acid Substitution↗
PubMed2000

A novel approach for inducing enhanced and selective transgene expression in hepatocellular-carcinoma cells.

Utility of the alpha-fetoprotein (afp) promoter for gene therapy against hepatocellular carcinoma (HCC) is limited because of the weak promoter activity. To circumvent this, the 5.1-kb 5;-flanking sequence of the human afp gene including the entire enhancer and silencer regions as well as the promoter region was employed for achieving strong, HCC-selective transgene expression. To thoroughly inhibit the promoter activity of the 5;-flanking sequence of the human afp gene, the afp 5;-flanking region was inserted downstream of the human interleukin-2 (il-2) gene controlled by the simian-virus-40 (SV40) early promoter. il-2-production ability of HCC cells transduced with the construct was significantly enhanced compared with that transduced with the same construct lacking the afp 5;-flanking region. Importantly, il-2 production of non-HCC cells was substantially inhibited by the addition of the afp 5;-flanking region to the construct. When the afp 5;-flanking region was inserted downstream of the human tumor-necrosis-factor-alpha (tnf-alpha) gene controlled by the retrovirus long-terminal-repeat (LTR) enhancer/promoter, tnf-alpha production ability of HCC cells was significantly enhanced and that of non-HCC cells was significantly suppressed compared with that transduced with the same construct lacking the afp 5;-flanking region. Our results indicated that the afp 5;-flanking region gave the enhanced HCC-selective activity to the non-tissue specific SV40 early promoter and LTR enhancer/promoter. It is essential for successful gene therapy to induce strong, target-cell-selective transgene expression. This novel strategy, therefore, may contribute to the establishment of HCC-selective cancer gene therapy.

3T3 Cells↗
PubMed2000

Cloning of three novel neuronal Cdk5 activator binding proteins.

Neuronal Cdc2-like kinase (Nclk) is involved in the regulation of neuronal differentiation and neuro-cytoskeleton dynamics. The active kinase consists of a catalytic subunit, Cdk5, and a 25 kDa activator protein (p25nck5a) derived from a 35 kDa neuronal-specific protein (p35nck5a). As an extension of our previous study (Qi, Z., Tang, D., Zhu, X., Fujita, D.J., Wang, J.H., 1998. Association of neurofilament proteins with neuronal Cdk5 activator. J. Biol. Chem. 270, 2329-2335), which showed that neurofilament is one of the p35nck5a-associated proteins, we now report the isolation of three other novel p35nck5a-associated proteins using the yeast two-hybrid screen. The full-length forms of these three novel proteins, designated C42, C48 and C53, have a molecular mass of 66, 24, and 57 kDa, respectively. Northern analysis indicates that these novel proteins are widely expressed in human tissues, including the heart, brain, skeletal muscle, placenta, lung, liver, kidney and pancreas. The bacterially expressed glutathione S-transferase (GST)-fusion forms of these three proteins were able to co-precipitate p35nck5a complexed with Cdk5 from insect cell lysate. Among these three proteins, only C48 and C53 can be phosphorylated by Nclk, suggesting that they may be the substrates of Nclk. Sequence homology searches have suggested that the C48 protein is marginally related to restin protein, whereas the C42 protein has homologues of unknown function in Caenorhabditis elegans and Arabidopsis thaliana.

Amino Acid Sequence↗
PubMed2000

A soluble transforming growth factor beta receptor expressed in muscle prevents liver fibrogenesis and dysfunction in rats.

We demonstrated that local expression of a dominant-negative type II TGF-beta receptor prevents live fibrogenesis and dysfunction in dimethylnitrosamine-treated rats. Using the same model, we have now tested whether a soluble TGF-beta receptor expressed in skeletal muscle can effectively suppress TGF-beta signaling in a remote organ (the liver). We constructed an adenovirus expressing an entire ectodomain of human TGF-beta type II receptor fused to the Fc portion of human IgG (AdTbeta-ExR). This soluble receptor secreted from AdTbeta-ExR-infected cells bound TGF-beta and blocked TGF-beta-signaling in vitro. After intramuscular injection of AdTbeta-ExR in rats, the soluble receptor protein was detectable in the blood for at least 3 weeks. When such rats were treated with dimethylnitrosamine, liver fibrosis was markedly attenuated without apparent systemic or local side effects. The hepatic hydroxyproline content was reduced to a level indistinguishable from that achieved by local expression of the dominant-negative TGF-beta receptor. Since a qualitatively and quantitatively similar suppression was achieved by the two methods, it may be concluded that the new strategy can achieve a complete inhibition of TGF-beta signaling under pathophysiological conditions in vivo. This strategy should facilitate clarification of the role of TGF-beta in vivo in various organs where direct gene transfer seems to be difficult.

Animals↗
PubMed2000

Laser pretreatment protects cells of broad bean from UV-B radiation damage.

In order to determine the role of lasers in the stress resistance of broad bean (Vicia faba L.) to ultraviolet-B (UV-B) radiation, the embryos in seeds were exposed to He-Ne laser or CO2 laser radiation. Afterwards they were cultivated in Petri dishes in a constant temperature incubator until the lengths of epicotyls were nearly 3 cm. The epicotyls were then exposed to 1.02, 3.03 or 4.52 kJ m(-2) UV-B radiation, respectively, under 70 micromol m(-2) s(-1) photosynthetically active radiation (PAR) in a growth cabinet. Changes in the concentration of malondialdehyde (MDA), ascorbic acid (AsA) and UV-B absorbing compounds (absorbance at 300 nm) were measured to test the effects of laser pretreatment. The results showed that laser pretreatment of embryos enhanced UV-B stress resistance in the epicotyls of the broad bean by decreasing the MDA concentration and increasing the content of AsA and UV-B absorbing compounds. We suggest that those changes in MDA, AsA and UV-B absorbing compounds were responsible for the increase in stress resistance observed in the broad bean. This is the first investigation reporting the use of laser pretreatment to protect the cells of the broad bean from UV-B-induced damage.

Ascorbic Acid↗
PubMed2000

Extracellular ATP-dependent activation of plasma membrane Ca(2+) pump in HEK-293 cells.

1. It is well known that extracellular ATP (ATP(o)) elevates the intracellular Ca(2+) concentration ([Ca(2+)](i)) by inducing Ca(2+) influx or mobilizing Ca(2+) from internal stores via activation of purinoceptors in the plasma membrane. This study shows that ATP(o) also activates the plasma membrane Ca(2+) pumps (PMCPs) to bring the elevated [Ca(2+)](i) back to the resting level in human embryonic kidney-293 (HEK-293) cells. 2. The duration of ATP(o)-induced intracellular Ca(2+) transients was significantly increased by PMCP blockers, La(3+) or orthovanadate. In contrast, replacement of extracellular Na(+) with NMDG(+), a membrane-impermeable cation, had no significant effect on duration, thus suggesting that Na(+)/Ca(2+) exchangers do not participate in the ATP(o)-induced Ca(2+) transient. 3. A rapid and significant decrease in [Ca(2+)](i), which was not dependent on extracellular Na(+), was induced by ATP(o) in cells pretreated with thapsigargin (TG). This decrease was blocked by orthovanadate, indicating that it was caused by PMCPs rather than sarco/endoplasmic reticulum Ca(2+) pumps (SERCPs). 4. UTP and ATPgammaS also caused a decrease in [Ca(2+)](i) in cells pretreated with TG, although they were less effective than ATP. The effect of UTP implies the involvement of both P2Y(1) and P2Y(2) receptors, while the effect of ATPgammaS implies no significant role of ectophosphorylation and agonist hydrolysis in the agonist-induced [Ca(2+)](i) decreases. 5. These results point to a role of PMCPs in shaping the Ca(2+) signal and in restoring the resting [Ca(2+)](i) level to maintain intracellular Ca(2+) homeostasis after agonist stimulation.

Adenosine Triphosphate↗
PubMed2000

Aromatic components of two ferric enterobactin binding sites in Escherichia coli FepA.

Ferric enterobactin is a catecholate siderophore that binds with high affinity (Kd approximately 10-10 M) to the Escherichia coli outer membrane protein FepA. We studied the involvement of aromatic amino acids in its uptake by determining the binding affinities, kinetics and transport properties of site-directed mutants. We replaced seven aromatic residues (Y260, Y272, Y285, Y289, W297, Y309 and F329) in the central part of FepA primary structure with alanine, individually and in double combinations, and determined the ability of the mutant proteins to interact with ferric enterobactin and the protein toxins colicins B and D. All the constructs showed normal expression and localization. Among single mutants, Y260A and F329A were most detrimental, reducing the affinity between FepA and ferric enterobactin 100- and 10-fold respectively. Double substitutions involving Y260, Y272 and F329 impaired (100- to 2500-fold) adsorption of the iron chelate more strongly. For Y260A and Y272A, the drop in adsorption affinity caused commensurate decreases in transport efficiency, suggesting that the target residues primarily act in ligand binding. F329A, like R316A, showed greater impairment of transport than binding, intimating mechanistic involvement during ligand internalization. Furthermore, immunochemical studies localized F329 in the FepA ligand binding site. The mutagenesis results suggested the existence of dual ligand binding sites in the FepA vestibule, and measurements of the rate of ferric enterobactin adsorption to fluoresceinated FepA mutant proteins confirmed this conclusion. The initial, outermost site contains aromatic residues and probably functions through hydrophobic interactions, whereas the secondary site exists deeper in the vestibule, contains both charged and aromatic residues and probably acts through hydrophobic and electrostatic bonds.

Alanine↗
PubMed2000

Marshall Urist Award. Interstitial collagenase gene expression correlates with in vitro invasion in human chondrosarcoma.

Matrix metalloproteinases contribute to the processes of local invasion and metastasis by providing cells with the ability to traverse tissue boundaries. The levels of gene expression were quantitated for matrix metalloproteinases-1 and tissue inhibitors of metalloproteinases-1 in human chondrosarcoma cell lines, and the results were correlated with cell differentiation, collagenase activity, and in vitro invasion. Three well characterized human cell lines were used in this study, with the level of chondrocytic differentiation confirmed to be JJ012, FS090, and 105KC in increasing order on the basis of aggrecan and collagen gene expression. The matrix metalloproteinases-1/tissue inhibitors of metalloproteinases-1 ratio correlated with the level of differentiation in an inverse fashion. Collagenase activity paralleled matrix metalloproteinases-1/tissue inhibitors of metalloproteinases-1 gene expression and was associated with a more invasive phenotype in an in vitro assay. In this report, matrix metalloproteinase-1 and tissue inhibitors of metalloproteinases-1 expression in human chondrosarcoma tumor cell lines were quantitated, and it was shown that interstitial collagenase gene expression correlates inversely with chondrocytic differentiation. Differences in collagenase activity and in vitro invasion correlate inversely with the level of differentiation. These findings are consistent with the hypothesis that collagenase activity is associated with a poorer prognosis in chondrosarcoma by facilitating cell egress from the tumor matrix.

Antineoplastic Agents↗
PubMed2000

Binding of ferric enterobactin by the Escherichia coli periplasmic protein FepB.

The periplasmic protein FepB of Escherichia coli is a component of the ferric enterobactin transport system. We overexpressed and purified the binding protein 23-fold from periplasmic extracts by ammonium sulfate precipitation and chromatographic methods, with a yield of 20%, to a final specific activity of 15,500 pmol of ferric enterobactin bound/mg. Periplasmic fluid from cells overexpressing the binding protein adsorbed catecholate ferric siderophores with high affinity: in a gel filtration chromatography assay the K(d) of the ferric enterobactin-FepB binding reaction was approximately 135 nM. Intrinsic fluorescence measurements of binding by the purified protein, which were more accurate, showed higher affinity for both ferric enterobactin (K(d) = 30 nM) and ferric enantioenterobactin (K(d) = 15 nM), the left-handed stereoisomer of the natural E. coli siderophore. Purified FepB also adsorbed the apo-siderophore, enterobactin, with comparable affinity (K(d) = 60 nM) but did not bind ferric agrobactin. Polyclonal rabbit antisera and mouse monoclonal antibodies raised against nearly homogeneous preparations of FepB specifically recognized it in solid-phase immunoassays. These sera enabled the measurement of the FepB concentration in vivo when expressed from the chromosome (4,000 copies/cell) or from multicopy plasmids (>100,000 copies/cell). Overexpression of the binding protein did not enhance the overall affinity or rate of ferric enterobactin transport, supporting the conclusion that the rate-limiting step of ferric siderophore uptake through the cell envelope is passage through the outer membrane.

Animals↗
PubMed2000

P2X(4) receptors mediate ATP-induced calcium influx in human vascular endothelial cells.

ATP induces Ca(2+) influx across the cell membrane and activates release from intracellular Ca(2+) pools in vascular endothelial cells (ECs). Ca(2+) signaling leads to the modification of a variety of EC functions, including the production of vasoactive substances such as nitric oxide and prostacyclin. However, the molecular mechanisms for ATP-induced Ca(2+) influx in ECs have not been thoroughly clarified. Here we demonstrate evidence that a P2X(4) receptor for an ATP-gated cation channel is predominantly expressed in human ECs and is involved in the ATP-induced Ca(2+) influx. Northern blot analysis distinctly showed the expression of P2X(4) mRNA in human ECs cultured from the umbilical vein, aorta, pulmonary artery, and skin microvessels. Competitive PCR revealed that P2X(4) mRNA expression was much higher in ECs than was the expression of other subtypes, including P2X(1), P2X(3), P2X(5), and P2X(7). Treatment of ECs with antisense oligonucleotides designed to target the P2X(4) receptor decreased the P2X(4) mRNA and protein levels to approximately 25% of control levels and markedly prevented the ATP-induced Ca(2+) influx.

Adenosine Triphosphate↗
PubMed2000

Gene variation of 5'-NCR and core region in serum samples collected from patients with HCV infection.

OBJECTIVE: To study the variation of HCV 5'-NCR and core gene in serial sera collected from patients with HCV infection. METHODS: Serial sera were collected from 4 plasma-donors with HCV infection. 5'-NCR and core gene were amplified, sequenced and analyzed using software. RESULTS: All the sequences obtained from the serial sera of patients with HCV infection were 1b and 2a subtypes. The variation of 5'-NCR only related to the genotype, and not associated with patients and time of serum collection. However, the sequences of core gene were not identical in HCV strains isolated from different patients. The sequences of those two regions of the same genotype isolated from the same patient did not change with time. CONCLUSION: 5'-NCR is more conserved than the core region and the genotype is the major cause of gene variation. No change in sequences of those two regions is found at the different points of time.

5' Untranslated Regions↗
PubMed2000

[Repairing peripheral nerve defects by tissue engineering techniques:an experimental study].

OBJECTIVE: To develop a novel effective substitute material or technique to repair peripheral nerve gap. METHODS: We inoculated expanded Schwann cells (SCs) at re-arranged bio-absorbable polymer polyglycolic acid (PGA) fiber and incubated for two weeks, then we developed a novel tissue-engineered scaffolds. The scaffolds were used as cellular isografts to bridge 15 mm long gap of sciatic nerve in inbred strains of Wistar rats. In an autologous and pure PGA fiber control group, the same surgical procedure was used. Evaluation included general observation, electromyographic examination, muscle measurement, and histological observation of serial sections at 12 weeks after surgery. The total number and density of reinnervation and thickness of myelin sheath was measured by computerized image analysis. RESULTS: SCs put out a long and thin prominence and migrated along the PGA fibers in spirality or parallel when they divided and finally rank into a cell-chain formation similar to Büngner's band. TEM/SEM and immunohistochemical survey demonstrated that the SCs at PGA fiber also secreted a great deal of ECMs included laminin, which play a very important role in peripheral nerve regeneration. Non-tubular scaffold comprised SCs and laminin (LN) channel in three-dimensional longitudinal rank. Animal transplantation study indicated the sensory and motor functional results of hindlimbs of experimental group rats reached to similar level of those found in nerve autograft control group. The number of reinnervation in the experimental group rats was slightly fewer than that in nerve autograft control group; but the axonal density was just reversal between the two groups because of a large area ischemic necrosis in the center of nerve autografts. CONCLUSION: This new paradigm offers a potential solution to repairing a long gap of peripheral nerve.

Animals↗
PubMed2000

[Genotyping of hepatitis C virus and homology analysis of its core gene sequences isolated from different geological regions].

OBJECTIVE: To study the structure of its genotypes and gene variation of hepatitis C virus (HCV) isolated from different geological regions. METHODS: Serum specimens were collected from patients with HCV infection of Henan and Hebei Provinces of China, as well as of Sweden and Germany. HCV RNA in their serum was detected by retro-transcription polymerase chain reaction (RT-PCR) and genotyped. The core gene of 11 HCV isolates were sequenced and their homology was analyzed for different geographic regions with software. RESULTS: Structure of HCV genotypes, isolated from two provinces of China, and from Sweden and Germany, was not identical. The homology of their core gene sequences of the same HCV genotype isolated from the same region was higher than that from different regions, and subtypes 1b and 2a were found in serum collected from China and subtypes 1a, 2c and 3a in serum from Sweden and Germany. CONCLUSION: Structure of HCV genotypes associated with their geographic distribution and difference in sequences of the same HCV genotype also associated with their geographic regions.

Base Sequence↗