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Biomedical subjects

L Zeng

Publications and source records attributed to L Zeng.

At least 73 records · Page 4Linked to original sources
PubMed2000

In vitro expression of hepatitis C virus non-structure 5 antigen in the HepG2 cell line.

To establish a cell line as a model system for HCV infection and propagation in vitro, a human HepG2 cell line was incubated with a HCV RNA positive serum. The sABC immunological techniques and gold-labeled colloid electron microscopy method were employed to examine the viral proteins in those cells. The HCV non-structure 5 antigen was first detected in the HepG2 cells 72 h after incubation. The antigen was continuously observed in the cytoplasm as well on the membrane of the HepG2 cells even after 1, 2, 3 and 4 weeks after incubation. The observation of HCV non-structure 5 antigen continuously expressed in the HepG2 cells strongly indicates that the cells may have been infected by HCV virus. Therefore, the HepG2 cell line may serve as a potential host for establishment of HCV infection and propagation in vitro.

Animals↗
PubMed2000

The role of TGF-beta 1 in mice hepatic fibrosis by Schistosomiasis Japonica.

To investigate the role of transforming growth factor-beta 1 (TGF-beta 1) in mice with hepatic fibrosis caused by Schistosomiasis Japonica, ELISA, VG staining and multimedia color hieroglyph quantitative analysis were used to study the change of the serum TGF-beta 1, liver collagen fiber and reticular fiber in mice. The level of serum TGF-beta 1 in experimental group was significantly higher than that in control group (P < 0.01 or P < 0.05) 8, 10, 12 weeks after infected by schistosomiasis. After infection, the level of liver collagen fiber and reticular fiber, and that of TGF-beta 1 increased over time (P < 0.01 or P < 0.05). In mice infected by Schistosomiasis Japonica, the level of TGF-beta 1 increased with prolongation of infection time, and with the increase of liver collagen fiber and reticular fiber. TGF beta 1 plays an important role of immunomodulation in hepatic fibrosis formation caused by Schistosomiasis Japonica.

Animals↗
PubMed2000

Study on biologic activity for membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus.

Using DPH fluorescence probe, the membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus (EHFV) was labeled. The membrane lipid fluidity was obviously decreased from the membrane lipid fluorescence polarization. The membrane lipid fluidity of lymphocyte, monocyte and neutrophilic granulocyte was dynamically observed. After culturing the cells for 1, 6, 24 and 72 h, it was found that all the membrane lipid fluidity of the infected cells was decreased obviously with the longer the culturing time, the more obvious it. Compared with the normal control groups, there was a significant difference statistically (P < 0.05-0.01). It was suggested that the decrease of the membrane lipid fludity of normal bone marrow cell with infection of EHFV had correlation with the degree of virus invading and cell-function injury.

Bone Marrow Cells↗
PubMed2000

Ineffective erythropoiesis in beta-thalassemia major is due to apoptosis at the polychromatophilic normoblast stage.

Beta-thalassemia major is characterized by ineffective erythropoiesis, although it is difficult to define the dynamics of this process from the static information revealed by analysis of bone marrow (BM) aspirates. We aimed to study the kinetics of sequential erythroid differentiation in beta-thalassemia major. We isolated the progenitor cells (CD34(+) and CD34(+)CD38(-) cells) from BM of thalassemia major patients and studied in vitro erythropoiesis. This is the first report of an in vitro study in human beta-thalassemia major from purified BM CD34(+) progenitor cells, using erythroid culture conditions, which allow unilineage differentiation to mature enucleated red blood cells. In contrast to normal donors, a high proportion of BM CD34(+) and CD34(+)CD38(-) progenitors from beta-thalassemia major coexpressed the late erythroid lineage-specific protein glycophorin A and generated a higher proportion of erythroid colonies. However, despite the marked increase in erythroid clonogenicity of the progenitor population, erythroid cultures initiated from beta-thalassemia major BM CD34(+) cells expanded 10- to 20-fold less than from normal BM. There were less viable cells during differentiation, specifically after the polychromatophilic normoblast stage. There was a progressive increase in the apoptotic erythroid progeny with differentiation, and apoptosis occurred predominantly at the polychromatophilic normoblast stage. In thalassemia major, BM progenitor cells show increased erythroid clonogenicity, increased expression of late erythroid lineage-specific proteins, and accelerated erythroid differentiation. However, despite the apparent increased erythroid commitment, ineffective erythropoiesis occurs due to apoptosis at the polychromatophil stage. Identification of the differentiation stage at which apoptosis occurs will permit further studies of the underlying mechanisms and target therapeutic strategies to improve red cell production.

ADP-ribosyl Cyclase↗
PubMed2000

Structural basis of SNT PTB domain interactions with distinct neurotrophic receptors.

SNT adaptor proteins transduce activation of fibroblast growth factor receptors (FGFRs) and neurotrophin receptors (TRKs) to common signaling targets. The SNT-1 phosphotyrosine binding (PTB) domain recognizes activated TRKs at a canonical NPXpY motif and, atypically, binds to nonphosphorylated FGFRs in a region lacking tyrosine or asparagine. Here, using NMR and mutational analyses, we show that the PTB domain utilizes distinct sets of amino acid residues to interact with FGFRs or TRKs in a mutually exclusive manner. The FGFR1 peptide wraps around the beta sandwich structure of the PTB domain, and its binding is possibly regulated by conformational change of a unique C-terminal beta strand in the protein. Our results suggest mechanisms by which SNTs serve as molecular switches to mediate the essential interplay between FGFR and TRK signaling during neuronal differentiation.

Adaptor Proteins, Signal Transducing↗
PubMed2000

An assessment of the clinical utility of serum ALT and AST in chronic hepatitis C.

Background: Alanine aminotransferase (ALT) is frequently used as the sole biochemical marker for chronic hepatitis C (CHC), however, its value may be normal in cases with active disease. Recently, aspartate aminotransferase (AST) has been suggested as a useful predictor of liver pathology and conflicting results were obtained by using AST/ALT ratio to predict cirrhosis. Aims: To evaluate clinical utility of serum ALT and AST in CHC. Methods: The charts of 133 patients with CHC, whose ALT and AST were simultaneously tested from 1994 to 1996, were reviewed. ALT and AST were analyzed for both the entire cohort of patients and subgroups stratified for histopathology, age, gender, alcohol consumption, and risk factors of transmission. In 53 patients, the AST/ALT ratio was evaluated during interferon treatment. Results: The elevation of ALT significantly correlated with that of AST (r=0.79). The AST/ALT ratio increased with liver histological progression. The ratio >/=1 was predominantly in cirrhotic patients. During treatment the ratio increased. The AST remained elevated in eight of the 33 patients in whom the ALT had returned to normal during and after treatment. Conclusions: Both ALT and AST are useful markers for CHC. However, the AST may elevate alone, suggesting that measuring AST may be useful when the ALT is consistently normal. The AST/ALT ratio varies in different patients but increases with histological progression of fibrosis. An AST/ALT ratio >/=1 is highly suggestive of the presence of cirrhosis.

Journal Article↗
PubMed2000

A new cembranolide from the soft coral Sinularia capillosa.

A new cembranolide, capillolide (1), and three known cembranolides were isolated from the soft coral Sinularia capillosa collected from the South China Sea. Their structures and the relative stereochemistry of 1 were deduced on the basis of spectroscopic methods.

Animals↗
PubMed2000

Characterizing rice lesion mimic mutants and identifying a mutant with broad-spectrum resistance to rice blast and bacterial blight.

Many plant mutants develop spontaneous lesions that resemble disease symptoms in the absence of pathogen attack. In several pathosystems, lesion mimic mutations have been shown to be involved in programmed cell death, which in some instances leads to enhanced disease resistance to multiple pathogens. We investigated the relationship between spontaneous cell death and disease resistance in rice with nine mutants with a range of lesion mimic phenotypes. All nine mutations are controlled by recessive genes and some of these mutants have stunted growth and other abnormal characteristics. The lesion mimics that appeared on the leaves of these mutants were caused by cell death as measured by trypan blue staining. Activation of six defense-related genes was observed in most of the mutants when the mimic lesions developed. Four mutants exhibited significant enhanced resistance to rice blast. One of the mutants, spl11, confers non-race-specific resistance not only to blast but also to bacterial blight. The level of resistance in the spl11 mutant to the two pathogens correlates with the defense-related gene expression and lesion development on the leaves. The results suggest that some lesion mimic mutations in rice may be involved in disease resistance, and cloning of these genes may provide a clue to developing broad-spectrum resistance to diverse pathogens.

Bacteria↗
PubMed2000

Vav3 mediates receptor protein tyrosine kinase signaling, regulates GTPase activity, modulates cell morphology, and induces cell transformation.

A recently reported new member of the Vav family proteins, Vav3 has been identified as a Ros receptor protein tyrosine kinase (RPTK) interacting protein by yeast two-hybrid screening. Northern analysis shows that Vav3 has a broad tissue expression profile that is distinct from those of Vav and Vav2. Two species of Vav3 transcripts, 3.4 and 5.4 kb, were detected with a differential expression pattern in various tissues. Transient expression of Vav in 293T and NIH 3T3 cells demonstrated that ligand stimulation of several RPTKs (epidermal growth factor receptor [EGFR], Ros, insulin receptor [IR], and insulin-like growth factor I receptor [IGFR]) led to tyrosine phosphorylation of Vav3 and its association with the receptors as well as their downstream signaling molecules, including Shc, Grb2, phospholipase C (PLC-gamma), and phosphatidylinositol 3 kinase. In vitro binding assays using glutathione S-transferase-fusion polypeptides containing the GTPase-binding domains of Rok-alpha, Pak, or Ack revealed that overexpression of Vav3 in NIH 3T3 cells resulted in the activation of Rac-1 and Cdc42 whereas a deletion mutant lacking the N-terminal calponin homology and acidic region domains activated RhoA and Rac-1 but lost the ability to activate Cdc42. Vav3 induced marked membrane ruffles and microspikes in NIH 3T3 cells, while the N-terminal truncation mutants of Vav3 significantly enhanced membrane ruffle formation but had a reduced ability to induce microspikes. Activation of IR further enhanced the ability of Vav3 to induce membrane ruffles, but IGFR activation specifically promoted Vav3-mediated microspike formation. N-terminal truncation of Vav3 activated its transforming potential, as measured by focus-formation assays. We conclude that Vav3 mediates RPTK signaling and regulates GTPase activity, its native and mutant forms are able to modulate cell morphology, and it has the potential to induce cell transformation.

3T3 Cells↗
PubMed2000

[Epizootic dynamics of Spodoptera litura nuclear polyhedrosi virus].

Through investigation of tracking infected Spodoptera litura larvae, the epizootic dynamics of S. litura nuclear polyhedrosis virus(SlNPV) in field was studied with different dosages of SlNPV. The results showed that in the range of virus dosages (3.1 x 10(5)-3.1 x 10(8) PIBs.ml-1), the initial infection syndrome was observed after 4 days of treatment, and peaked in 5-7 days. The larvae mortality occurred after 5-6 days of treatment, and peaked in 6-8 days. The prevalence peak of host was basically coincident to the incidence peak. The distribution of diseased incidence of hosts and disease death time could be quite simulated by time-dosage-mortality model(TDM). Hosmer-Lemoshow test showed that the predicted values well fitted with observed data, and t-test indicated the parameters of the model reached significant level(P < 0.0001). The distribution of diseased prevalence was simulated by Holliday model, the regression of function was significant by F-test, and the parameters of the model reached or approached significant level(p < 0.005). TDM model could be used to predict the daily incidence, prevalence, disease death rate of present generation population of host pest.

Animals↗
PubMed2000

[Distribution of interleukin-6 receptors (CD(126) and CD(w130)) on circulating lymphocytes in patients with lupus nephritis].

OBJECTIVE: To study the distribution of IL-6 receptors (CD(126) and CD(w130)) on lymphocytes in patients with lupus nephritis (LN). METHOD: The percentages of lymphocyte subsets were examined by direct two colour immunofluorescence on flow cytometry. RESULTS: (1) In active and inactive cases, the percentages of CD(+)(4) cells obviously decreased as compared with the normal controls (P < 0.01). Increased numbers of CD(+)(8) cells could be detected in LN patients (P < 0.05), especially in active cases (P < 0.01). Lymphocytes of active cases contained significantly greater percentage of CD(+)(23) cells than those of normal subjects (P < 0.05). On the contrary, the percentage of CD(+)(23) cells was statistically lower in the inactive cases than in normal subjects (P < 0.01). No significant difference in the percentages of CD(+)(126) and CD(+)(w130) cells was observed among the active, inactive and healthy groups (P > 0.05); (2) The proportion of CD(+)(4) CD(+)(126) and CD(+)(4) CD(+)(w130) cells in total lymphocytes was significantly lower in the active than in the inactive ones or normal subjects (P < 0.05; P < 0.01), whereas that of CD(+)(8) CD(+)(126) and CD(+)(8) CD(+)(w130) cells was not different among the active, inactive and normal subjects (P > 0.05). The proportion of CD(+)(23) CD(+)(126) cells and CD(+)(23) CD(+)(w130) cells augmented significantly in the active (P < 0.05), whereas it lessened in the inactive without statistical meaning as compared with the normal subjects (P > 0.05). (3) There was a positive correlation between the percentage of CD(+)(23) CD(+)(126) cells and that of CD(+)(23) CD(+)(w130) cells in total lymphocytes in the active group (r = 0.756, P < 0.05). However, no correlation between the percentage of CD(+)(23) CD(+)(126) cells and that of CD(+)(23) CD(+)(w130) cells in total lymphocytes was found in the inactive (r = 0.376, P > 0.05) or normal group (r = 0.256, P > 0.05); (4) The fraction of CD(+)(23) cells expressing CD(126) and CD(w130) was related to the SLE disease activity index (SLEDAI) and lymphopenia (P < 0.05, P < 0.005). But it was neither associated with the number of damaged organs and the degree of damage, not with that of ANA, anti-dsDNA antibody and complements (C(3) and C(4)) (P > 0.05). CONCLUSIONS: LN patients present not only B cell hyperactivity but also T cell abnormality. In active cases, there is abnormal distribution of IL-6 receptors on lymphocytes: reduced CD(126) and CD(w130) expression on CD(+)(4) cells and elevated CD(126) and CD(w130) expression on CD(+)(23) cells. Detecting the proportion of CD(+)(23) CD(+)(126) cells or CD(+)(23) CD(+)(w130) cells in total lymphocytes may serve as one of activity indexes for LN patients.

Adolescent↗
PubMed2000

[Expression of VEGF and tumor angiogenesis in bladder cancer].

OBJECTIVE: To evaluate expression of vascular endothelial growth factor (VEGF) and its relation to angiogenesis in bladder cancer. METHODS: The expression of VEGF by immunohistochemical staining was examined in 68 cases of primary transitional carcinoma (TCC) and 7 subjects with normal urothelium. Microvessel density (MVD) in 40 cases of invasive bladder cancer was determined by Factor VIII immunohistochemical staining. RESULTS: The expression of VEGF was negative or low level in all normal bladder tissue but high in bladder cancer. VEGF and MVD were closely related to tumor cell nuclear grade and clinical stage. The average MVD was higher in the cases with the high level expression of VEGF, than in those with the low level expression of VEGF. CONCLUSIONS: This study indicates that VEGF is positively correlated with the occurrence and progression of bladder cancer. VEGF is one of the primary angiogenic factors for bladder cancer, and is able to induce tumor angiogenesis and accelerate tumor growth. Quantification of VEGF may provide a valuable marker for a poorer prognosis of patients.

Adult↗
PubMed2000

[Tracheal transplantation].

OBJECTIVE: To treat long tracheal cancer by tracheal transplantation. METHODS: In March 17, 1999, a patient received a total laryngeal resection and a resection of 8 cm upper and middle trachea, which was replaced by a 6 cm long trachea of another donor. The donor trachea was dipped first in preservation liquid A for sterilization for 24 hours, then in preservation liquid B for over 48 hours for destructing MHC. Pedunculated greater omentum and pedunculated greater pectoral musculus supplied the blood for the donor trachea. One side of the donor was anastomosed with the lower trachea, and the other with the neck skin. RESULTS: The patient survived 300 days after operation. The auto tracheal membrane covered the donor surface; auto- and xeno trachea was well anastomose. The new trachea grew very well. CONCLUSION: Trachea transplantation is possible the best method to treat long tracheal disease if the transplantable trachea is less 5 cm.

Aged↗
PubMed2000

[The detection of disparity evoked potentials in anisometropes].

OBJECTIVE: To investigate the affection of anisometropia on stereopsis and its mechanism. METHODS: A new set of static random-dot stereograms was utilized as a stimulus to elicit evoked potentials in 20 anisometropes and 40 normal subjects. RESULTS: Under the stimulus of different degrees of disparity in anisometropes, the P(250) waves related to stereopsis could be recorded. However, the percentage of their P(250) wave amplitude over the plane figure was significantly lower than that of normal persons (P < 0.05). The P(250) wave mean amplitude of severe anisometropes (aniseikonia >or= 5%) in fine disparity (14' and 23') was lower than that in mild anisometropes (aniseikonia < 5%, P < 0.05). CONCLUSIONS: Anisometropia may affect and disturb the stereopsis. The degree of disturbance is related to the degree of anisometropia. The higher the degree of anisometropia, the lower the amplitude of the P(250) potential, and the main defect is at the part of fine disparity.

Adolescent↗
PubMed2000

[Chemical composition of essential oil in stems, leaves and flowers of Agastache rugosa].

The chemical components and their relative contents of essential oil in different parts (stems, leaves and flowers) of Agastache rugosa have been analyzed by GC-MS technique, and 32 kinds of chemical structures in these three kinds of oils have been identified. Among which, it included 24 kinds in leaf-oil, 27 in stem-oil and 22 in flower-oil. The principal components in all these three kinds of oils were methylchavicol (60.01-88.43%), and other important components were d-limonene, caryophyllene, hexadecanoic acid, linoleic acid, octahydro-7-methyl-methylene-4-(1-methylethyl)-1H-cyclopenta [1, 3] cyclopropa [1, 2] benzene, etc.

Agastache↗
PubMed2000

[Isolation and identification of a new long-chain tetrahydroxyamide].

A novel long chain tetrahydroxyamide compound (C42H85NO5, mp 178-180 degrees C) has been isolated from Polymastia sobustia collected from the South China Sea. On the basic of the spectral data of IR, MS, 1H NMR, 13C NMR, DEPT and chemical way, the compound was identified as N-(1-hydroxymethyl-2,6-dihydroxyl) heptadecyl-5-hydroxyltetracosanamide, sobustiamide.

Amides↗
PubMed1999

Protein tyrosine phosphatase alpha (PTPalpha) and contactin form a novel neuronal receptor complex linked to the intracellular tyrosine kinase fyn.

Glycosyl phosphatidylinositol (GPI)-linked receptors and receptor protein tyrosine phosphatases (RPTPs), both play key roles in nervous system development, although the molecular mechanisms are largely unknown. Despite lacking a transmembrane domain, GPI receptors can recruit intracellular src family tyrosine kinases to receptor complexes. Few ligands for the extracellular regions of RPTPs are known, relegating most to the status of orphan receptors. We demonstrate that PTPalpha, an RPTP that dephosphorylates and activates src family kinases, forms a novel membrane-spanning complex with the neuronal GPI-anchored receptor contactin. PTPalpha and contactin associate in a lateral (cis) complex mediated through the extracellular region of PTPalpha. This complex is stable to isolation from brain lysates or transfected cells through immunoprecipitation and to antibody-induced coclustering of PTPalpha and contactin within cells. This is the first demonstration of a receptor PTP in a cis configuration with another cell surface receptor, suggesting an additional mode for regulation of a PTP. The transmembrane and catalytic nature of PTPalpha indicate that it likely forms the transducing element of the complex, and we postulate that the role of contactin is to assemble a phosphorylation-competent system at the cell surface, conferring a dynamic signal transduction capability to the recognition element.

Animals↗