Biomedical subjects

Yan Ji

Publications and source records attributed to Yan Ji.

26 records · Page 2Linked to original sources

PubMed2003

Generation of an HFRS patient-derived neutralizing recombinant antibody to Hantaan virus G1 protein and definition of the neutralizing domain.

Hantaan virus (HTNV) in the Hantavirus genus, family Bunyaviridae, is the major cause of severe hemorrhagic fever with renal syndrome (HFRS). We prepared a combinatorial phage display library of human Fabs to HTNV from RNA extracted from the blood lymphocytes of a convalescent HFRS patient. We selected two G1 glycoprotein-specific clones and one nucleocapsid protein (N)-specific clone from the Fab library for further studies. The human Fab antibodies were converted to IgG form in baculovirus/insect cells system by using cassette vectors that we developed earlier. Characterization of the recombinant antibodies revealed that the two G1-specific IgGs, could bind to and neutralize HTNV but not Seoul virus (SEOV). The N-specific IgG did not neutralize either HTNV or SEOV. Sequence analysis revealed that the two G1-specific clones differed by only one predicted amino acid in their complementarity determining regions, CDR3. Epitope mapping studies were carried out with one of the two G1-specific clones and synthetic peptides representing portions of HTNV G1. Results indicated that the recombinant antibody recognizes the core amino acid sequence LTKTLVIGQ, which is found near the C-terminus of HTNV G1. These results are the first to define a neutralizing epitope on the G1 protein of HTNV using an antibody derived from an HFRS patient.

Antibodies, Viral↗

PubMed2003

[Generation of human recombinant antibody Fab fragment and its IgG to adeno-associated virus type II from phage display library].

BACKGROUND: To acquire the recombinant human monoclonal antibodies and IgG to adeno-associated virus type 2 (AAVs-2). METHODS: Construct and pan human Fab antibody library to AAVs-2 was established from normal volunteer donors by using phage display technology and secreted expression in E.Coli system. The positive Fab clones were selected and characterized through ELISA and immunofluorescent assay, and then the heavy and light chain were sequenced. The gene of light chain and heavy chain Fd fragment of recombinant mAb were inserted into baculovirus expression vector pAC-L-Fc and construct expression vectors of intact IgG, then transfected insert sf-9 cell secreted expression in Baculovirus/Insert system. Immunoprecipitation test was used to detect its recognizing region. RESULTS: One clone named AAVs-31 showed positive responses in ELISA and IFA, the Fab was composed of gamma chain and kappa chain IgG was positive in ELISA and IFA. The IgG failed to detect nonassembled or denatured capsid proteins, but recognized the AAVs-2 stock from immunoprecipitation test. CONCLUSION: The authors isolated a clone of Fab and IgG to adeno-associated virus type 2 by phage display technology, they perhaps recognize an epitope which is formed during capsid assembly.

Amino Acid Sequence↗

PubMed2002

Signaling of monocytic differentiation by a non-hypercalcemic analog of vitamin D3, 1,25(OH)2-5,6 trans-16-ene-vitamin D3, involves nuclear vitamin D receptor (nVDR) and non-nVDR-mediated pathways.

Exposure of leukemia cells to the physiologically active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25D3) normalizes their phenotype to cells that resemble mature monocytes. One of the earliest detectable events in this process is an upregulation of the nuclear receptor for 1,25D3, the vitamin D receptor (nVDR). In contrast, the novel analog of 1,25D3, 1,25-dihydroxy-5,6 trans-16-ene-vitamin D3 (5,6-16D3), which has recently been reported to have low calcium-mobilizing activity in vivo, rapidly induced the expression of CD14, CD11b, and monocyte-specific esterase (MSE), classical markers of the mature monocyte, but upregulated nVDR expression less than 1,25D3. This upregulation was shown to be the result of altered degradation of the nVDR protein, while the levels of nVDR mRNA were constant. Knock-out of nVDR transcriptional activity by a decoy VDRE double-stranded deoxyoligonucleotide, markedly abrogated 1,25D3-induced differentiation, but incompletely inhibited 5,6-16D3-induced differentiation. These findings suggest that the unique ability of 5,6-16D3 to induce cell differentiation but not systemic hypercalcemia, may be due to the activation of pathways which initiate differentiation independently of nVDR.

Antineoplastic Agents↗

PubMed2002

Numerical studies on the effect of lowering temperature on the oxygen transport during brain hypothermia resuscitation.

There have been arguments about the advantage and shortcoming of hypothermia on the brain resuscitation during circulation arrest. People usually accepted that hypothermia may decrease the cerebral oxygen demands, which is beneficial for the patient to sustain longer time when subjected to a hypoxia. However, there are also quite a few disputes claiming that the blood viscosity would increase with the reduction of temperature, which may lead to an increase of cerebral vascular resistance and thus worsen the hypoxia state. To resolve this critical issue, a heat transfer model was established to characterize the thermal response of brain tissue during hypothermia resuscitation. Combined with this model, a compartmental model taking account of the temperature effect was further developed to analyze the transient oxygen partial pressure (PO(2)) distribution over the successive branches of the vascular network during circulation arrest. Using the morphological and physiological data of a sheep brain, effects of lowering temperature on the oxygen consumption dynamics were studied. Calculations indicated that the lower the temperature, the slower the decreasing rate for the PO(2). Although immediately lowering the brain temperature may induce an evident increase in blood viscosity and subsequently a decrease in blood flow rate, which is responsible for oxygen delivery, it seems to always result in a monotonic increase of PO(2). The results show a good qualitative accord with the experimental data. They also present better understanding on the transient oxygen transport in brain hypothermia during circulation arrest.

Animals↗

PubMed2002

[The expression of FN-IIIcs in the wound healing and its relationship with injury time].

OBJECTIVE: To research the expression of alternative splicing segment of fibronectin-IIIcs in incised wound of skin, to offer the experimental data for early injury time judgement. METHODS: Using in situ hybridization with DIG-labeled anti-sense RNA probe, the expression of FN-IIIcs domain was detected in both human and rat skin incised wound. RESULTS: (1) The expression of FN-IIIcs improved from the time of 30 min after injury, reached peak at 6 h and then reduced gradually. (2) The positive expression cells were mainly distributed in hair follicles, sebaceous glands and endothelium, however, in human beings they were basement cells of epidermis. CONCLUSION: The expression of FN-IIIcs domain would be a supposed useful criteria for early injury time judgement.

Animals↗

PubMed1999

Effect of cell fusion on metastatic ability of mouse hepatocarcinoma cell lines.

AIM:To study the effect of cell fusion on metastatic ability of mouse hepatocarcinoma cells and the factors involved in the process of metastasis.METHODS: By the method of successively increasing the concentrations, cell fusion and limit dilution, 8-Ag resistant cells were selected, and HGPRT-Hca-P cells and eight cloned hybridoma cells were obtained. To observe their metastatic ability, they were inoculated into mice foodtaps and the drainage lymph nodes were examined under microscope.RESULTS:The end concentration of 8-Ag which was used to select HGPRT deficient Hca-P cells was 30mg/L.All the cells selected died in HAT culture medium in one week.Fused cells appeared approximately 9 days later. They were round, transparent and a little larger than their parental cells. Eight clones of hybridoma cells were obtained and named as PSH1-PSH8. The metastatic rate of HGPRT-Hca-P cells and PSH7 cells was 28.6% and 71.4% respectively, the difference being significant (P < 0.05). The metastatic rate of other clones was no more than 20% and there was no significant difference from HGPRT-Hca-P cells (P >0.05).CONCLUSION:In normal mice splenic lymphocytes, there are some factors that could inhibit tumor metastasis, however, there are some other factors accelerating tumor cells to metastasize. The establishment of PSH7 provides an experimental model which could be used to study the factors involved in metastasis.

Journal Article↗

PubMedDate not supplied

Membrane transport of dietary phenethyl isothiocyanate by ABCG2 (breast cancer resistance protein).

Isothiocyanates (ITCs) are non-nutrient constituents abundant in cruciferous vegetables and are effective in blocking carcinogenesis in a variety of tissues. ITCs permeate into cells rapidly and accumulate in cells primarily as glutathione (GSH) conjugates. We have demonstrated recently that certain ITCs are inhibitors of ABCG2 (breast cancer resistance protein, BCRP), an ATP-binding cassette transporter that plays an important role in drug absorption and disposition as well as in the development of multidrug resistance in cancer cells. The purpose of this study was to investigate the mechanisms of interactions between ITCs and BCRP and elucidate the transport of phenethyl isothiocyanate (PEITC) by BCRP. Inside-out membrane vesicles were prepared from human breast cancer BCRP-overexpressing MCF-7/MX100 and the parental MCF-7/sensitive cells. The ATPase study using 100 muM ITCs showed that ITCs are potential inhibitors of BCRP ATPase activity. The transport of (14)C-PEITC into BCRP-overexpressing MCF-7/MX100 cell vesicles was ATP-dependent and inhibited by fumitremorgin C (FTC), a specific inhibitor of BCRP, indicating that PEITC is a substrate for BCRP. In the control MCF-7/sensitive cell vesicles, no ATP-dependent and FTC-inhibited transport of (14)C-PEITC was observed. Taken together, the results of this investigation provided evidence that ITCs are potential inhibitors of BCRP ATPase and PEITC, in its unchanged form, is transported by BCRP. These data may be important in elucidating the interaction of ITCs and cellular transporters and in understanding the potential food-drug interaction.

ATP Binding Cassette Transporter, Subfamily G, Mem↗

PubMedDate not supplied

Derivatives of vitamins D2 and D3 activate three MAPK pathways and upregulate pRb expression in differentiating HL60 cells.

Analogs of vitamin D have been synthesized which have reduced calcemic activities yet increased anti-proliferative and differentiation-inducing properties, raising expectations that they will be useful for treatment of human neoplastic diseases. In the present study we compared the abilities of three such analogs, 24a, 24b-dihomo-1,25-dihydroxyvitamin D(3) (PRI-1890), 24-ene-1,25-dihydroxyvitamin D(2) (PRI-1906) and (24R)-1,24-dihydroxyvitamin D(3) (PRI-2191) to induce markers (CD14, CD11b and MSE) of differentiation, G(1) phase block, and associated molecular events in human promyeloblastic leukemia cells HL60. We found that the potencies of the analogs to induce differentiation paralleled their activation of Erk, JNK and p38 mitogen-activated protein kinase (MAPK) pathways, and the anti-proliferative activity closely correlated with the extent of hypophosphorylation of retinoblastoma protein (pRb). Interestingly, low concentrations of derivatives of vitamin D, which were insufficient to induce any detectable changes in the cell cycle traverse, markedly increased the levels of total pRb, which was highly phosphorylated. These results suggest that pRb may have an unsuspected role in monocytic differentiation, perhaps to increase the sensitivity of the G(1) checkpoint, by increasing the amount of substrate for cyclin-dependent kinases.

Biomarkers↗